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TEMPORAL AND SPATIAL VARIABILITY OF BLENNY (PERCIFORMES:
LABRISOMIDAE AND BLENNIIDAE) ASSEMBLAGES ON TEXAS JETTIES
A Thesis
by
Timothy Brian Grabowski
Submitted to the Office of Graduate Studies of
Texas A&M University
in partial fulfillment of the requirements for the degree of
MASTER OF SCIENCE
December 2002
Major Subject: Wildlife and Fisheries Sciences
TEMPORAL AND SPATIAL VARIABILITY OF BLENNY (PERCIFORMES:
LABRISOMIDAE AND BLENNIIDAE) ASSEMBLAGES ON TEXAS JETTIES
A Thesis
by
Timothy Brian Grabowski
Submitted to the Office of Graduate Studies of
Texas A&M University
in partial fulfillment of the requirements for the degree of
MASTER OF SCIENCE
Approved as to style and content by: _____________________________
André M. Landry, Jr. (Chair of Committee)
_____________________________
Jaime R. Alvarado Bremer (Member)
_____________________________
William H. Neill (Member)
_____________________________
Jay R. Rooker (Member)
_____________________________
Wyndylyn M. von Zharen (Member)
_____________________________
Robert D. Brown (Head of Department)
3
ABSTRACT
Temporal and Spatial Variability of Blenny (Perciformes: Labrisomidae and Blenniidae) Assemblages on
Texas Jetties. (December 2002)
Timothy Brian Grabowski, B.S. Texas A&M University
Chair of Advisory Committee: Dr. André M. Landry, Jr.
Structured, hard-bottom habitats and associated cryptic fish species were effectively absent from
the northwestern Gulf of Mexico coast prior to jetty construction 120 years ago. Fishes in the Families
Labrisomidae and Blenniidae now distributed across the northwest Gulf may have been influenced by jetty
construction. Little is known about the species composition, population dynamics, or origin(s) of blenny
assemblages on Texas jetties. In this study, blennies were dipnetted monthly from jetty habitats at
Galveston, Port Aransas, and South Padre Island, Texas, during May 2000 through August 2001; and in
Florida, once during December 2001 to characterize assemblage structure. All specimens (n=4555) were
identified, enumerated, and measured and a subsample taken for otolith microstructure analysis (n=99) and
mtDNA sequencing (n=67). Four blenniid species (Hypleurochilus geminatus, Hypsoblennius hentz,
Hypsoblennius ionthas, and Scartella cristata) and one labrisomid (Labrisomus nuchipinnis) contributed
to spatially distinct assemblages differing significantly in species composition, diversity and evenness
across sampling sites. Galveston exhibited the highest diversity index values while Port Aransas yielded
the most species (4). Temperature appears to be the driving factor behind species composition over time
at each sampling site. Scartella cristata dominated blenny assemblages on Texas jetties regardless of local
environmental conditions and was found to be a short-lived species with an extended spawning period.
The Galveston population of S. cristata exhibited the statistically highest mean total length and age and
demonstrated a close affinity to Florida conspecifics, thus indicating the eastern Gulf to be a likely source.
Scartella cristata on the lower and middle Texas coast originated from at least two sources, suggesting
two genetically distinct populations may exist in the Gulf. Jetty construction on the Texas coast has
allowed these two populations to mix.
4
DEDICATION
This work is dedicated to the three special women in my life. To my grandmother, Dolores, who
always taught me to be true to myself and though she is gone will never be forgotten. To my mother, Jane,
who has never faltered in her belief in me. And to my wife, Laura, who is a source of constant inspiration
because she looks upon this world with a sense of wonder and amazement that I envy. I succeed because
of what each of you gives to me.
5
ACKNOWLEDGMENTS
No journey of discovery is taken alone and this was no exception. I would like to show my deep
appreciation to my committee, André Landry, Jay Rooker, Jaime Alvarado Bremer, William Neill, and
Wyndylyn von Zharen for their unwavering support, patience, and willingness to teach me. I would like to
thank Raymond Bauer and his students Aaron Baldwin and Greg Hess at Louisiana State University at
Lafayette, Scott Bean, Brian Bloodworth, Cristine Chapman, Danny English, Bert Geary, Laura
Grabowski, Joseph Heaton, Casey Hughart, Lyndsey McDonald, Benjamin Rhame, Kelly Rullo, Tucker
Slack, and Joanne Walczak for their assistance in both the field and laboratory, this project could not have
been completed without them. I would like to thank the Department of Marine Biology at Texas A&M
University at Galveston, the TAMUG Research Management Office, and Leonard Kenyon of the Sea
Turtle and Fisheries Ecology Research Laboratory for their logistical support of this project. And last but
not least, the Southeast Texas Sportfishing Association and The Aquarium at Moody Gardens for their
generous financial support of this project.
6
1INTRODUCTION
Fishes of the Families Blenniidae and Labrisomidae are cryptic residents of structured inshore
and offshore marine habitats worldwide (Bond 1996). Blenniidae is a varied and speciose family with 345
species in 53 genera, the majority of which occur in the Indo-Pacific (Nelson 1994). Because blenniids
are typically restricted to structurally complex, hard-bottomed substrates such as reefs and rocky
shorelines, the Texas Gulf shore probably represented a historical gap in their range prior to construction
of jetties. Nevertheless, ten species in the Family Blenniidae occur on nearshore jetties, groins, and
pilings; offshore oil platforms, banks, and reefs; and estuarine oyster reefs in the northwestern Gulf of
Mexico (Britton and Morton 1989, Hoese and Moore 1998). Two of these, striped blenny, Chasmodes
bosquianus (Lacepéde) and Florida blenny, Chasmodes saburrae Jordan and Gilbert, are restricted to low
salinity, estuarine habitats (Springer 1959) and are not likely residents of nearshore or offshore waters.
Additionally, C. saburrae is thought to be restricted to parts of Florida where there is a gap in the range of
C. bosquianus (Hoese 1958, Springer 1959). Two other species, barred blenny, Hypleurochilus
bermudensis Bebee and Tee-Van, and feather blenny, Hypsoblennius hentz (Lesueur), are not commonly
encountered along the Texas coast (Hubbs 1939, Randall 1966, Hoese and Moore 1998). The only known
records of Hypleurochilus bermudensis in the northwestern Gulf come from the West Flower Garden
Banks (Randall 1966, Bright and Cashman 1974, Hoese and Moore 1998). Hypsoblennius hentz is
somewhat more common, occurring on soft mud bottoms in south Texas bays rather than along jetties of
the middle and upper Texas coast (Hubbs 1939, Smith-Vaniz 1980, Hoese and Moore 1998). Three other
species, tessellated blenny, Hypsoblennius invemar Smith-Vaniz and Acero, redlip blenny, Ophioblennius
atlanticus (Valenciennes), and seaweed blenny, Parablennius marmoreus (Poey), are frequently found on
offshore reefs and production platforms but are uncommon in nearshore habitats (Bright and Cashman
1974, Hoese and Moore 1998). Molly miller, Scartella cristata (Linneaus), and crested blenny,
Hypleurochilus geminatus (Wood) are common on jetties and groins but have been known to occur on
structured habitats in estuarine systems (Lindquist and Chandler 1978, Hoese and Moore 1998). Hoese
This thesis follows the style of Marine Ecology Progress Series.
7
and Moore (1998) indicate that Hypleurochilus geminatus is the most frequently encountered blenny on
the lower Texas coast and imply that Scartella cristata is relatively scarce on the middle and upper coast.
The freckled blenny, Hypsoblennius ionthas (Jordan and Gilbert), also is a typical inhabitant of jetties and
groins but occurs more frequently on estuarine oyster reefs (Hubbs 1939, Clarke 1979, Smith-Vaniz 1980,
Hoese and Moore 1998).
The Family Labrisomidae is another group of blennies occurring on Texas jetties (Hoese 1958,
Springer 1958, Hoese and Moore 1998). While there are 102 known labrisomid species in 16 genera
(Nelson 1994), not much is known about their ecology, life history, or population dynamics (Springer
1958, Hoese and Moore 1998). The hairy blenny, Labrisomus nuchipinnis (Quoy and Gaimard), is the
only species regularly occurring on the Texas coast (Hoese 1958, Hoese and Moore 1998). Little is
known about L. nuchipinnis except that it ranges throughout the tropical and subtropical Atlantic (Springer
1958, Hoese and Moore 1998) but avoids sandy beaches, river deltas, and mangroves (Springer 1958).
Blennies have been the focus of diverse research efforts ranging from behavior to aquatic
toxicology. However, existing information on population dynamics of blennies in the northwestern Gulf
of Mexico is limited, particularly when compared to that of counterparts in the Caribbean, Mediterranean,
and northeast Atlantic Ocean. These studies tend to focus on a single species and not multi-species
systems where differences in biology of constituent species can be determining factors in assemblage
structure. The Texas coast encompasses a wide range of environmental and climatic regimes (Britton and
Morton 1989) that have the potential of influencing growth. Growth is an important aspect in structuring
species assemblages (Jones 1991); however, there is no information available on the growth rates of Gulf
of Mexico blennies. Therefore an attempt to characterize these assemblages would be incomplete without
recognizing the importance of an age and growth component.
Blennies and the “New” Texas Coast
The Texas coast has historically been an unbroken 650 km stretch of sandy beaches. Rocky shore
habitats are practically absent in nearshore waters of the northwest Gulf, with the nearest natural rocky
shores occurring at Punta Jerez in Tamaulipas, Mexico (Britton and Morton 1989). There is significantly
more hard-bottom habitat in offshore waters of the northwest Gulf but these areas are relatively small, low
8
relief features isolated from each other by large expanses of flat mud bottoms (Bright 1977, Dennis and
Bright 1988). With the exception of the Flower Gardens Banks and other smaller associated banks, few if
any of these naturally occurring hard-bottom habitats are suitable for blenny colonization as a result of the
Gulf’s oceanographic and bathymetric characteristics (Rezak et al. 1985). Other structure-dependent
fishes such as lutjanids and serranids flourish not only on banks and reefs of the northwestern Gulf but on
low relief features, such as shell ridges, while blenniids are absent from these habitats (Rezak et al. 1985,
Harper 2002). Sediment input from the Mississippi River creates a sunlight-blocking layer of suspended
material known as the nephloid layer that effectively limits the depth to which algae can grow on
nearshore features of the northwest Gulf. Consequently, the distribution of herbivorous blenniid species is
restricted to features that extend above the nephloid layer. Extensive oyster reefs located in primary and
secondary bays behind barrier islands are the only other naturally occurring hard-bottom habitats along the
Texas coast. However, fluctuations in temperature and salinity associated with these estuarine
environments limit blenny assemblages to species such as Chasmodes and Hypsoblennius spp. that tolerate
these changing conditions (Springer 1957, Crabtree and Middaugh 1982, Britton and Morton 1989, Hoese
and Moore 1998).
Human activities have altered the physical nature of the Texas coast dramatically over the past
140 years. Ensuring the flow of commerce and protecting beaches have resulted in the creation of a
limited amount of rocky shore habitat in the form of jetties and groins. Jetty construction along the Texas
coast began in 1868 and continued into the 1920’s (Alperin 1977). Currently seven major passes are
protected by jetties: Sabine Pass, Bolivar Roads, Freeport Ship Channel, Matagorda Ship Channel,
Aransas Pass, Mansfield Cut, and Brazos Santiago Pass. Many other small jetties and groins such as those
at Fish Pass on Mustang Island, Texas and at Veracruz and Tampico, Mexico protect passes and shoreline
along the western Gulf. Groins were constructed along the Galveston Island beachfront in the 1930’s to
protect both the beach and seawall (Alperin 1977).
Jetties represent structurally stable and permanent habitats to associated fauna in contrast to a
coastline characterized by shifting sand and bottoms of unconsolidated muds and sands (Bohnsack et al.
1991). Texas jetties are essentially new “islands” in the Gulf of Mexico where planktonic spores, eggs,
9
and larvae of organisms that must settle on solid substrate to survive have suitable habitat on which to
recruit. Many fish species probably are still colonizing and establishing new populations on Texas jetties
but unfortunately no comprehensive study of these processes has been undertaken. Due to jetties’ recent
construction and relative isolation, their biotic community may be impoverished when compared to that of
naturally occurring rocky shores and reefs of the eastern Gulf, southern Gulf, and Caribbean as well as
estuarine oyster reefs (Britton and Morton 1989).
Blennies are recent arrivals to the Texas Gulf coast, utilizing jetties as surrogate habitat. The
blenniid species found on the Texas coast have probably closed a gap in their historic range by colonizing
jetties (Hoese and Moore 1998, Britton and Morton 1989); yet their original source population(s) of
individuals comprising this recruitment has not been identified. It also is unknown if blennies have
established self-maintaining populations—a possibility in light self-recruitment in reef fish populations
(Stobutzki and Bellwood 1997, Jones et al. 1999, Swearer et al. 1999), or if their persistence is dependent
upon recruitment from outside sources.
The three components of the present study (habitat and assemblage characterization; age and
growth; population genetics) enabled broad questions regarding the past, present, and future of these
assemblages to be addressed. The history of blenny assemblages on Texas jetties was reconstructed using
molecular techniques and focused on the question: do assemblages present on Texas jetties today represent
an extension from a single source or a convergence of multiple populations? The current status of blenny
assemblages was documented through collections along the Texas coast and focused on the question: how
are blenny assemblages on jetties structured along the Texas coast? Combining these data with
characterization of jetty habitat and age and growth of the dominant species allowed questions regarding
the underlying reasons for observed patterns to be raised. The future of blenny assemblages on Texas
jetties also was considered including the long-term impact jetties may have on the genetic structure of
blenny populations in the Gulf and potential practical applications of this study to conservation and
management of marine resources.
10
OBJECTIVES
1.) Characterize blenny assemblages on Texas jetties and groins.
a. Document the species composition and size structure of these assemblages and
assess their spatial and temporal variability.
b. Determine the species diversity and evenness of these assemblages.
c. Identify hydrographic parameters critical to observed distribution.
2.) Characterize age and growth patterns of the dominant blenny species on Texas jetties.
a. Compare mean age of local populations across sampling sites.
b. Determine growth rates across sampling sites.
c. Assess spawning periodicity of conspecifics across sampling sites.
3.) Document the genetic structure of the dominant blenny species on Texas jetties.
a. Determine the genetic interaction/differentiation among sites in Texas.
b. Determine the genetic interaction/differentiation among sites in Texas and Florida.
c. Identify the most likely origin(s) of recruits to Texas jetties.
11
METHODS
Study Areas
Blenny assemblages of Texas jetties were characterized at upper, middle, and lower coast
locations (Fig. 1). The upper coast study area consisted of an 8 km stretch of beachfront on Galveston
Island in Galveston County, Texas (Fig. 2). Ten groins, each extending gulfward from the Galveston
beachfront for approximately 50 m, collectively comprised the only sampling station on the upper coast
(Table 1). Groins were sampled in Galveston as opposed to the South Jetty at Bolivar Roads on the east
end of the island due to safety concerns. Surf conditions and currents at the South Jetty were typically
much more severe than those at the groins. Integrating the 10 smaller groins into one station was designed
to reduce mortality associated with repeated sampling at these sites. Although the majority of effort was
concentrated on two groins (the 44th and 49th Street groins), samples taken from other groins did not differ
in CPUE, species composition, or size of individuals from those taken from more heavily fished
counterparts during the same month.
The South Jetty bordering Aransas Pass in Port Aransas, Nueces County, was the middle coast
study area (Fig. 2). This jetty runs extends gulfward in a south-southeast direction for approximately 2000
m. Two collection stations were established at the South Jetty, station 2 on the north or Aransas Pass side
and station 3 on the south or Gulf side. Both stations were sampled concurrently whenever possible, but
wind and surf conditions frequently rendered monthly samples possible at only one station.
Lower Texas coast collections were made at the North Jetty protecting Brazos Santiago Pass on
South Padre Island, Cameron County (Fig. 2). This jetty extends east-west into the Gulf for approximately
2000 m. Like those for the middle coast, two collection stations were established at the North Jetty-station
4 on the north or Gulf side and station 5 on the south or channel side near a protected cove (Dolphin
Cove).
Characterization of Blenny Habitat
Blenny habitat was characterized by describing two distinct aspects of the jetty environment:
hydrographic conditions and substrate complexity. Hydrographic characterization was based on water
12
N
S
EW
29° 15.00’
28° 10.00’
27° 05.00’
26° 00.00’
98° 35
.00’
97° 30
.00’
96° 25
.00’
9 5°20
.00’
94° 15.0
0’
Gulf of Mexico
Galveston
Port Aransas
South Padre Island
TexasHouston
Corpus Christi
Brownsville
Fig. 1. Map of upper, middle, and lower coast study areas used to characterize blennyassmeblages on Texas jetties from May 2000 to August 2001. Highlighted boxes represent study areas sh own in greater detail in Fig. 2.
Gulf of M exico
13
Fig. 2. Collection stations at Galveston (STATION 1), Port Aransas(STATIONS 2 and 3) and South Padre Island (STATIONS 4 and 5), TX studyareas.
Port AransasSTATIONS 2 and 3
May 2000-
August 2001
97° 1
0.4’
97° 0
8.2’
97° 0
6.0’
97° 0
3.8’
97° 0
1.6’
27° 51.5’
27° 49.9’
27° 50.8’
27° 49.1’
San Jose Island
Mustang Island
2
3
Aransas Pass
South Jetty
GalvestonSTATION 1
May 2000-
August 2001
94° 5
5.8’
94° 5
3.5’
94° 5
0.9’
94° 4
8.4’
29° 18.8’
29° 13.8’
29° 16.2’
94° 4
5.9’
Galveston Island
1
Galveston Bay
South PadreIsland
STATIONS 4 and 5
July 2000-
August 2001
97° 1
1.1’
97° 1
0.3’
97° 0
9.6’
97° 0
8.9’
26° 05.0’
26° 03.5’
26° 04.3’
97° 0
8.2’
Laguna Madre
Brazos Santiago Pass
4
5
South PadreIsland
North Jetty
14
temperature, salinity, and turbidity measurements made prior to each sampling event. Surface water
temperature was measured to the nearest degree Celsius using an alcohol-filled thermometer. Salinity was
measured to the nearest part per thousand using an optical refractometer. Turbidity was measured to the
nearest 0.1 centimeter using a 0.26-m diameter secchi disc.
Substrate complexity of each collection site was assessed by measuring rugosity of the
constituent jetty surface. Rugosity was measured with 1-m lengths of 20-gauge stainless steel wire
molded to the surface of the jetty below the water line. The shortest straight-line distance between the two
ends after the wire was molded to the jetty’s surface was then measured. The inverse ratio of this distance
to the original length of the wire yielded an index value of rugosity. Rugosity was measured at three
different locations chosen at random along the length the 15-m transects established for sampling after
each collection effort. The structural complexity of blenny habitat also was assessed qualitatively through
visual examination by noting fouling community coverage and species composition as well as general jetty
construction (i.e. small vs. large boulders, placements of boulders, occurrence of crevices).
Characterization of Blenny Assemblages
Surf conditions permitting, three collections were conducted monthly at each upper, middle,
lower coast station from May 2000 through August 2001 (July 2000 to August 2001 for South Padre
Island). Blennies were captured in a 25.4 x 17.5 cm rectangular dipnet randomly swept along a 15-m
transect against the jetty. Each collection was based on approximately 60 minutes of sampling for a total
of 3 hours of effort expended at respective stations every month. If more than one collector was present,
Table 1. Location of Galveston Islan d, TX stations and the months each was sampled.
STATION NAME M ONTH(S) SAMPLED1A 19th Street gro in DEC 001B 21st Stree t groin JUL 001C 24th Stree t groin OCT 00, JUN O11D 27th Street gro in JUN 00, JUN 011E 33rdStre et g roin MAY 00, JUN 001F 37th Street gro in M AR 001G 40th Street gro in JUL 001H 44th Street gro in APR 00, AUG 00, APR 011I 49th Street gro in JUN 00-NOV 00, JAN 01-MAR 01, MAY 01- AUG 011J 51st Stree t groin MAR 01, APR 01
15
each worked a different 15-m transect for the same amount of time with their efforts considered two
distinct collections. A paired sample t-test indicated no significant difference between collections made
by different collectors at the same time and station. Depth of capture ranged between that of algae mats at
the supralittoral fringe to approximately 1.5 m below the surface; however, water depth at most stations
was considerably deeper than the area within reach of the sampling gear. Captured blennies were held in
aerated 18.9-L buckets until completion of the collection. Other captured fishes were noted and released.
Blennies were then sacrificed by immersion in MS-222, rinsed, and stored in 70% ethanol. Blennies were
identified to species, enumerated, and measured (total length) to the nearest millimeter.
Mark and Recapture Studies
A mark-recapture study was conducted at respective locations to estimate relative abundance of
constituent blenny species. Three mark-recapture experiments based on a minimum of 50 blennies
collected from 10-m transects were conducted at each location. Each collection was initially placed in an
aerated 18.9-L bucket and eventually transferred to another 18.9-L bucket containing seawater and the fish
anesthetic quinaldine. Anesthetized fish were identified to species and marked using visible fluorescent
elastomer injected subdermally above the anal fin (Guy et al. 1996, Gibson 1999). Marked fish were
placed into another aerated 18.9-L bucket and allowed to recover before being released near their capture
site. The same 10-m transects of jetty at each location were re-sampled 24 hours later and the number of
marked and unmarked blennies within respective species recorded. Blennies captured in this second
collection were sacrificed and used in the protocols described under Characterization of Blenny
Assemblages (p. 10).
Otolith Microstructure Analysis
Sagittal otoliths were removed from Scartella cristata (n=106) captured from Galveston, Port
Aransas, and South Padre Island from May through September 2000. S. cristata was chosen because it
was encountered across all three localities. Individuals representing the range of sizes and collection dates
were selected for further analysis. Otoliths were prepared following the protocols outlined by Secor et al.
(1991) and Rooker and Holt (1997). Otoliths were individually mounted in blocks of Spurr resin and
sectioned using an Isomet™ isometric saw (Buehler, Lake Bluff, IL). Each section was then attached to a
16
microscope slide with Crystal Bond glue (Aremco Products Inc., Ossining, NY) and polished to the core
on both sides using 240, 320, 400, and 600 grit Carbimet™ paper discs, Microcloth™ polishing cloth, and
Micropolish™ 0.3 micron alpha alumina (Buehler, Lake Bluff, IL). Age of each individual was then
determined by counting daily growth increments from the core to the post rostrum (Fig. 3) under a
compound light microscope using OPTIMAS® version 6.0 image analysis software (Media Cybernetics,
Inc., Silver Spring, MD).
Daily increment formation was validated by marking otoliths with alizarin complexone. Thirty-
four Scartella cristata were held in a 250 mg/L alizarin complexone-seawater solution for approximately
60 minutes to stain their otoliths. Individuals were then maintained in 75.8-L aquariums and sacrificed
after 10 days (n=14), 17 days (n=6), and 30 days (n=14). Sagittal otoliths were removed from these
specimens and prepared as outlined above. Both the number of growth increments and distance between
the alizarin complexone mark and otolith’s post-rostral edge were measured. Least squares linear
regression and ANOVA were performed to evaluate the relationship between the amount of otolith growth
and time. The validation model was confirmed through analysis of covariance (ANCOVA) comparing 10-
20 day increments measured at randomly chosen positions on the otolith to increment widths calculated
Fig. 3. Light microscope photograph of the sagital otolith of Scartella cristata viewed at 100 X magnification. Arrows indicate a representative sample of daily growth rings.
17
for the same time period by the model. The validation trial confirmed that one ring represented one day’s
growth but there was some uncertainty in reading the most recent rings on the otolith’s edge. Based on the
alizarin complexone marking, otoliths grew at the rate of 0.33 μm/day. The validation model was
compared to a least squares regression of a series of readings along short transects on the otolith surface
(Fig. 4). While not a perfect match, ANCOVA validated the regression estimates of growth rate (p=0.943)
and size-at-hatching (p=0.171).
Age-length relationships were used to estimate growth of Scartella cristata. Hatch dates for all S.
cristata captured under 270 mm TL were calculated by subtracting the estimated age in days from the date
of capture. Individuals that exceeded 270 days old were excluded from the analysis due to an inability to
discern their daily growth rings. No attempt was made to weigh large individuals during analysis to
account for the cumulative effect of mortality on an age class because no published estimate of blenny
mortality was found.
Incr
emen
t wid
th (u
m)
Days
0
5
10
20
15
5 10 2015 25 30 35
Increment Width=0.4078*Days+5.74 61R2=0.4157
VALIDATION MODELIncrement Width=0.33*Days-0.34
Fig. 4. Comparison between the va lidation model of otolith growth increments and daily rings on the sagital otoliths of Scartella cristata a nd least squares regression of readings a nd increment width measures on the otolith surface.
18
Mitochondrial DNA D-Loop Analysis
Genetic analysis was performed on a subsample of Scartella cristata to identify relationships
between sample sites and determine the origin(s) of individuals on Texas jetties. The null hypothesis that
Texas jetties represented a single undifferentiated population originating from a single source population
was tested. To this end, individuals ranging from 40 to 50 mm TL were selected from Galveston (n=20),
Port Aransas (n=19), and South Padre Island (n=19) samples to minimize variation that may occur
between age classes (Fig. 4). An additional nine individuals were collected from Gulf Islands National
Seashore on Santa Rosa Island, Florida in December 2001 for use in this analysis (Fig. 5). DNA was
extracted from these individuals following protocols described by Greig (2000) with minor modification.
Briefly, approximately 0.05 g of epaxial muscle tissue was added to a labeled 1.5 μL microfuge tube with
200 μL of TENS solution (50 mM Tris-HCl [pH 8.0], 100 mM EDTA, 100 mM NaCl, 1.0% SDS) and 20
Santa Rosa Island, Floridan=9Galveston Island, Texas
n=20
Port Aransas, Texasn=19
South Padre Island, Texasn=19
Fig. 5. Capture locations of Scartella cristata used in mtDNA an alysis.
19
μL of Proteinase K (10mg/ml) and incubated 10-12 hours at 55 C on a heat block. Nucleic acids were
precipitated by adding 20 μL of 5 M NaCl and then spun at 14,000 g for 10 minutes. The sample
supernatant was pipetted into a second microfuge tube and approximately 400 μL of 100% cold ethanol
was added to precipitate DNA. The sample was spun again at 14,000 g for 10 minutes and the resulting
supernatant discarded. DNA pellets were washed by adding 300 μL of 70% cold ethanol, spun again at
14,000 g, and the resulting supernatant was discarded. Pellets were allowed to air-dry overnight. The
DNA was resuspended in 100 μL of TE buffer (10 mM Tris-HCl [pH 8.0], 1 mM EDTA) and placed on a
heat block at 65 C until the pellet fully dissolved. The presence and quality of extracted DNA was verified
by electrophoresis of 3 μL of resuspended DNA through a 1.0% agarose gel at 100 V for approximately 30
minutes. DNA was visualized using ethidium bromide.
Polymerase chain reaction (PCR) was performed to amplify a 380 base pair segment of the
mtDNA D-loop region using the heavy strand primer CSBD-H (5’-CCGGTCTGAACTCAGATCACGT-
3’) and light strand primer L15998-PRO (5’-TACCCCAAACTCCCAAAGCTA-3’). PCR was conducted
in Eppendorf Mastercycle Gradient (Brinkmann Instruments Inc., Westbury, NY) with the following
reaction profile: initial denatuaration for 2 minutes at 94.0 C followed by 35 cycles (denaturation, 30
seconds at 94.0 C; annealing, 45 seconds at 50.0 C; extension, 1 minute at 72.0 C) and a final extension
for 3 minutes at 72.0 C. Electrophoresis through a 1.2 % agarose gel at 100 V for approximately 30
minutes was used to examine the quality of PCR product and check for contamination. Again, ethidium
bromide was used for visualization. Upon successful PCR, the product was cleaned of excess dNTP,
primers, and AmpliTaq® using ExoSAPIT® (USB Corporation, Cleveland, OH) following manufacturer’s
recommendations. Clean PCR products were prepared for cycle sequencing using a BigDye® terminator
cycle sequencing ready reaction kit (Applied Biosystems, Foster City, CA). Cycle sequencing was
performed in an Eppendorf Mastercycler Gradient with the following reaction profile: 25 cycles
(denaturation, 10 seconds at 96.0 C; annealing, 5 seconds at 50.0 C; extension, 4 minutes at 60.0 C). Upon
completion of cycle sequencing, the product was cleaned using RapXtract® II dye terminator removal kit
(Prolinx, Bothell, WA) and diluted in 30 μL of dd H2O. Single strand nucleotide sequences were obtained
20
using the ABI Prism 310 Genetic Analyzer (Applied Biosystems, Foster City, CA) at the Molecular
Ecology and Fisheries Genetics Laboratory at Texas A&M University at Galveston.
Data Analysis
With the exception of DNA sequence data, all data analysis and statistical tests were performed
using SPSS for Windows version 10.0.1 (SPSS Inc., Chicago, IL). Means are reported ± 1 standard
deviation unless otherwise noted. The assumptions of parametric testing (normality, equality of variance,
etc.) were validated and transformations were conducted when necessary. In the cases where a violation
of assumptions could not be reconciled through transformation, the data (salinity and turbidity) were log
transformed to minimize any effects of excessive variability and the appropriate test performed
(Underwood 1981, 1997).
Habitat characterization: Hydrographic measurements were grouped by season for analysis and a mean
calculated for each parameter during summer (June-August), autumn (September-November), winter
(December-February), and spring (March-May). Means for respective parameters were compared across
seasons within a given location and between localities during each season using one-way analysis of
variance (ANOVA). Significant differences (α=0.05) were identified with the Tukey post-hoc test.
Turbidity data were log transformed to meet ANOVA’s assumption of equal variance.
Mean rugosity for each location was compared using a one-way ANOVA and Tukey post-hoc
test to determine if substrate complexity of collection sites at upper, middle, and lower coast jetties
differed significantly from one another (α=0.05). Log transformation was necessary to satisfy the
assumption of equal variance. Qualitative data were used to validate rugosity measures and to account for
any observed differences.
Blenny assemblage characterization: Species diversity was measured for each collection using the
Shannon-Wiener diversity index,
n
ffnnH
k
iii∑
=
−=′ 1
loglog
21
where n is the total number of blennies captured and f represents the number of individuals of each blenny
species (Zar 1996). Species evenness, J ′ , was calculated as
maxHHJ′′
=′
where kH logmax =′ and k represents the number of blenny species (Zar 1996). The mean monthly
values of H ′ and J ′ for upper, middle, and lower coast stations were calculated and compared using one-
way ANOVAs with Tukey post-hoc tests to identify significant differences (α=0.05).
Catch per unit effort (CPUE), defined as the number of blennies per sampling-hour, was
calculated for constituent species in each collection while mean seasonal CPUE was calculated for each
species. Mean seasonal CPUE was compared across sites and among seasons at each locality with
ANOVA and Tukey post-hoc tests. Analysis of covariance (ANCOVA) was used to determine if
temperature, salinity, turbidity, date, or location correlated with CPUE. Inverse transformation
(transformed CPUE=CPUE-1) allowed for all assumptions to be met.
The monthly and overall mean total length were calculated for each species and compared within
locations over time and between locations using ANOVA with Tukey post-hoc tests or t-tests where
appropriate (α=0.05). Length-frequency distributions also were generated for constituent species in each
collection. The total length data could not be reconciled with the assumptions of parametric testing. All
analysis was conducted with log-transformed data.
Mark and recapture: Population size within respective species was estimated using the Petersen equation,
1)1(
++
=RCMN
where N is the population estimate, M is the number of blennies initially marked, R is the number of
marked blennies recaptured, and C is the total number of fish captured in the second sampling effort (Guy
et al. 1996).
Age and growth: Differences in growth rates of Scartella cristata among the three study sites were
determined through linear regression and ANCOVA. Age-length relationships generated for each site
22
were used to estimate the age of every Scartella cristata captured from that site during the study. Overall
mean age at each site was calculated and compared among locations using ANOVA with Tukey post-hoc
tests.
Genetic analysis: DNA sequences were visually aligned and edited using BioEdit Sequence Alignment
Editor version 5.0.7 (Hall 1999). DNA polymorphisms in the aligned sequences and genetic variation
within samples were assessed through calculations of nucleotide diversity (π) and haplotype diversity (h)
using DnaSP version 3.51 (Rozas and Rozas 1999). Genetic distances were estimated using the Tamura-
Nei model with pairwise deletion, and a neighbor-joining tree with 500 bootstrap replicates was
constructed using MEGA version 2.1 (Kumar et al. 2001). TCS version 1.13 (Clement et al. 2000) was
used to identify haplotypes and determine haplotype relationships. Analysis of molecular variance
(AMOVA) was performed using Arlequin version 2.000 (Schnieder et al. 2000) to determine the
proportion of genetic diversity within and among sample sites (ΦST). AMOVA calculates the difference
between mean heterozygosity among population subdivisions and potential frequency of heterozygotes
using a modification of Wright’s F-statistic (Excoffier et al. 1992). It operates under the assumptions that:
individuals in the sample are selected independently and at random; individuals within the population can
interbreed randomly and non-assortatively; and there is no inbreeding within the population (Excoffier
1992). The number of migrants per generation (Nm) among samples sites also was estimated using
Arlequin. Mismatch distributions of the frequency of a given number of pairwise differences were
generated for each location with Arlequin. These distributions were compared to a Poisson distribution
with the same mean as the using chi-square test. Distributions that differed significantly (α=0.05) from the
Poisson distribution indicated samples were taken from a population of constant size, whereas failure to
reject the null hypothesis suggested the population has been growing exponentially for an extended period
of time (Slatkin and Hudson 1991). Mantel’s test with 1000 permutations was performed using TFPGA
version 1.3 (Miller 1997) to determine if a significant relationship existed between genetic distances and
geographical distances among locations.
23
RESULTS
Habitat Characterization
Water temperature at the three study sites was similar (Fig. 6). Temperatures peaked in late
summer and early fall (Galveston: 32.0°C; Port Aransas: 31.0°C; South Padre Island: 31.7°C) and then
declined to their minimum in December and January (Galveston: 13.0°C; Port Aransas: 14.0°C; South
Padre Island: 14.0°C). Overall mean water temperature from spring 2000 to summer 2001 was 23.1±6.7,
25.0±6.1, and 24.1±4.9°C for Galveston, Port Aransas, and South Padre Island, respectively. Significant
seasonal differences in temperature were observed at each study site (Galveston: p<0.001; Port Aransas:
p<0.001; South Padre Island: p=0.007). Mean summer water temperature at Galveston (Fig. 6) was
significantly higher in both 2000 (31.4±1.9°C) and 2001 (30.1±2.4°C) than that of other seasons (spring
2000: 25.0°C; fall 2000: 18.7±3.2°C; winter 2000-01: 15.0±2.0°C; spring 2001: 20.5±4.9°C). Winter
2000-01 (15.0±1.0°C) produced the only significant within site comparison at Port Aransas, being cooler
than the other seasons (spring 2000: 25.0°C; summer 2000: 30.5±1.5°C; fall 2000: 26.5±3.5°C; spring
2001: 25.0±3.5°C; summer 2001: 30.2±1.3°C), while the winter 2000-01 (17.0±3.0°C) and spring 2001
(23.0±2.6°C) means were significantly lower than those of all other seasons at South Padre Island
(summer 2000: 28.3±1.1°C; fall 2000: 28.0±4.2°C; summer 2001: 26.9±1.2°C) (Fig. 6). There were no
significant differences among the three sites in mean seasonal water temperature (p=0.736) or in the
overall mean water temperature (p=0.732); however winter water temperatures tended to be warmer on the
middle and lower coasts while their summer counterparts were warmer on the upper and middle coasts.
Salinity remained relatively constant throughout the year at all three study sites (Galveston: 24.0-
34.3‰; Port Aransas: 29.9-36.0‰; South Padre Island: 31.3-35.0‰) (Fig. 6). Overall mean salinity was
28.3±6.7, 32.3±5.9, and 33.0±4.9‰ for Galveston, Port Aransas, and South Padre Island, respectively.
Seasonally there were no significant differences at any site (Galveston: p=0.206; Port Aransas: p=0.128;
South Padre Island: p=0.433), but a trend toward lower salinities in winter increasing through the summer
did exist. While there were no significant differences in mean seasonal salinity among sites (p=0.236),
there was a significant difference in overall mean salinity (p=0.004). Salinity tended both to be higher and
24
less variable from north to south along the coast. Galveston had significantly lower overall mean salinity
than did Port Aransas (p=0.016) and South Padre Island (p=0.007). There was no significant difference
between Port Aransas and South Padre Island (p=0.92).
Turbidity, as estimated by secchi disc measurements, remained relatively constant in Galveston
(25-55 cm) during the study period. In Port Aransas turbidity peaked in spring 2001 (40 cm) and was
lowest in summer 2001 (144 cm) while that at South Padre Island ranged from 135 cm in fall 2000 to 51
cm in summer 2000. Turbidity typically decreased from north to south, with overall mean estimates for
Galveston, Port Aransas, and South Padre Island being 34.2±11.4, 79.7±52.6, and 88.0±54.8 cm,
respectively. Galveston yielded significantly higher overall mean turbidity (p<0.001) than did Port
Aransas (p=0.002) and South Padre Island (p<0.001). Mean seasonal turbidity in Galveston during
summer 2000 (55.3±4.2 cm) and winter 2000-01 (37.3±8.3 cm) differed significantly (summer: p=0.035;
winter: p=0.026) from those of other seasons (Fig. 6). Seasonal turbidity at Port Aransas also differed
statistically (p=0.023), with summer 2001 estimates (143.6±62.9 cm) being lower than those of either
winter 2000-01 (p=0.031; mean=40.2±9.2 cm) or spring 2001 (p=0.038; mean=36.9±10.6 cm). South
Padre Island failed to yield significant differences (p=0.434) in mean seasonal turbidity. However, its
mean estimates were significantly lower than those of Galveston (p=0.045) during fall 2000 and of
Galveston (p=0.003) and Port Aransas (p=0.027) during winter 2000-01.
There were small but significant differences in rugostiy or structural complexity across the study
sites. Mean values were 1.15±0.1, 1.15±0.08, and 1.21±0.08 for Galveston, Port Aransas, and South Padre
Island, respectively (Fig. 7). ANOVA indicated significant differences in mean rugosity among sites
(p=0.029). Galveston had significantly lower rugosity than did South Padre Island (p=0.043). Groins on
25
the Galveston beachfront were largely bare rock with a poorly developed fouling community of barnacles,
oysters, and filamentous epilithic algae. While the rocks of the South Jetty at Aransas Pass did not appear
to differ structurally from those of Galveston, the biological complexity of their fouling community was
much greater. The South Jetty was mostly covered by dense mats of filamentous and foliose epilithic
0
5
15
25
35
30
20
10Tem
pera
ture
(C
)
0
5
15
25
35
40
30
20
10
Sal
inity
(ppt
)
0
5 0
100
150
200
250
Sec
chi d
isc
read
ing
(cm
)
SPRING 2000
S UM MER 2000
WINTE R 2000-01
FALL 2000
SP RING 2001
S UM MER 2001
Galveston South Padre IslandPort AransasFig. 6. Mean seasonal water temperature, salinity, and secch i disc estimates of turbidity at Galveston, Port Aransas, and South Padre Island, TX from Spring 2000 to Summer 2001. Error bars represent standard error.
26
algae that often grew on extensive beds of mussels and barnacles. The North Jetty at Brazos Santiago Pass
exhibited little difference in the structural complexity of the rocks, but the arrangement of the rocks on the
channel side of the jetty created habitats that were similar to tide pools. Its rocks also were almost
completely covered by thick epilithic algae mats comprised of structurally complex species in the genera
Caulerpa and Padina. In places, calcareous remains of Padina formed growths resembling hermatypic
coral. Density and distribution of mussel and barnacle beds on the North Jetty were more restricted than
that at the other two sites (Fig. 7).
Characterization of Blenny Assemblages
A
0.50
0.25
0
0.75
1.25
Galv eston Port Aransas South Padre Island
Rug
osity
Inde
x
Galveston Port Ara nsas South Padre Island
Fig. 7. Comparison of quantitative and qualitative measures of habitatcomplexity at Texas groins and jetties. (A) Mean rugosity indices for the groins/jetties at Galveston, Port Aransas, and South Padre Island. Error bars represent standard error. (B) Examples of the typical development of the jetty fouling community.
B
1.00
27
Species Composition
A total of 4555 blennies representing five species (Labrisomus nuchipinnis, Hypleurochilus
geminatus, Hypsoblennius hentz, Hypsoblennius ionthas, and Scartella cristata) was captured from the
three study sites during May 2000 through August 2001. Catch statistics for these species and study sites
are summarized in Table 2. Catch per unit effort (CPUE) of blennies and species composition varied
temporally and spatially. Temperature (p<0.001), location (p=0.005), and their interaction (p=0.017) had
a significant effect on CPUE, yielding a coefficient of determination of 0.596. ANCOVA indicated that
turbidity (p=0.526), date (p=0.774), and salinity (p=0.936) had no significant effects on CPUE, despite
r2=0.572 when all environmental parameters were factored into the analysis.
Spe cie s Ga lve ston Port Aransa s South Padre Island TOTALLabrisom us nuchipinnis 0 9 80 89
Hypleurochilus gem inatus 199 65 24 288Hypsoblennius hentz 0 6 0 6
Hypsoblennius ionthas 59 0 0 59Scartella cristata 194 1867 2052 4113TOTAL 452 1947 2156 4555
Table 2. Total blenny catch from groins/jetties at Galveston, Port Aransas, and South Padre Island, TX during May 2000through August 2001.
Collections in Galveston consisted primarily of Hypleurochilus geminatus and Scartella cristata
that were caught in statistically similar numbers (p=0.519) during the study. Hypleurochilus geminatus’
CPUE ranged from 0 to 10.2 to produce an overall mean of 3.2±3.7. Monthly CPUE of this species
peaked during early summer and again secondarily in August 2000 but declined through the fall and
winter (Fig. 8). Overall mean CPUE of S. cristata was 3.6±3.3, with monthly catch rates ranging from 0
to 12.0. Scartella cristata CPUE peaked in mid to late summer and declined through January before
increasing again by early spring (Fig. 8). Hypsoblennius ionthas also was captured at Galveston during
spring and summer 2000, with CPUE peaking at 14.1 in May 2000 (Fig. 8). Thereafter, they were only
encountered again in May 2001 in low numbers (0.4) to yield an overall mean CPUE of 1.3±3.5. Overall
mean CPUE for all species at Galveston was 8.1±7.7.
Four blenny species, Labrisomus nuchipinnis, Hypleurochilus geminatus, Hypsoblennius hentz,
and Scartella cristata, were captured at Port Aransas. For all species combined, overall mean CPUE was
28
35.4±42.9. Scartella cristata was the dominant blenny with CPUE ranging from 0.7 to 141.9 and an
overall mean of 33.9±42.9. CPUE remained relatively high throughout the year but peaked in late summer
24
2 1
1 8
1 5
1 2
9
6
3
0 0
5
1 0
1 5
2 0
2 5
30
35
4 0
CPU
E (#
of b
lenn
ies/
net-
hour
)S
alinity (ppt) and Tem
perature (C)
Hypleurochilus geminatus Hy psoblennius ionthas Scartella crista ta
Salinity Temperature
Fig. 8. Blenny catch pe r unit effort (CPUE), salinity (ppt) and water temperature (C) at groins on the Galve ston Island, TX beachfront during May 2000 through August 2001.
MA
Y
JUN
JUL
AU
G
SEP
OC
T
DE
C
NOV
JAN
FEB
MA
R
AP
R
MA
Y
JUN
JUL
AUG
2000 2001
Hypl eurochilus geminatus Scartella crista taLabrisomus nuchipinnis
Salinity Temperature
Fig. 10. Blenny ca tch per unit effort (CPUE), salinity (ppt) and wa ter temperature (C) at the North Jetty on South Padre Island, TX during May 2000 through August 2001.
24
21
18
15
12
9
6
3
0 0
5
10
15
20
25
3 0
3 5
40
CPU
E (#
of b
lenn
ies/
net-
hour
)Salinity (ppt) and Tem
perature (C)
237.7 99.9 55.6 76.7
NO E
FFO
RT
NO
EFF
OR
T
NO
EFF
OR
T
MA
Y
JUN
JUL
AUG
SEP
OC
T
DEC
NOV
JAN
FE
B
MA
R
AP
R
MA
Y
JUN
JUL
AUG
2000 2001
29
and declined quickly by mid winter (Fig. 9). Except for one Hypleurochilus geminatus, S. cristata was the
only species captured on the Gulf side of the jetty (station 3) where its overall mean CPUE was 96.8±94.9.
Although S. cristata also dominated blenny catches on the channel side of the jetty (station 2), its overall
mean CPUE (10.8±9.9) was significantly lower (p<0.001) at station 2 than that of station 3.
Hypleurochilus geminatus had an overall mean CPUE of 1.2±1.1 and monthly means ranging from 0 to
3.8. Catches of Hypleurochilus geminatus peaked during late spring and summer (July in 2000; May in
2001) and declined until early spring (Fig. 9). Port Aransas was the northernmost capture site for L.
nuchipinnis where it exhibited an overall mean CPUE of 0.2±0.4. Monthly mean CPUE ranged from 0 to
1.6, with catch following a temperature related pattern (Fig. 9). The six Hypsoblennius hentz captured at
Port Aransas in May 2000 (CPUE=0.78) were the only representatives encountered during this study.
Only Labrisomus nuchipinnis, Hypleurochilus geminatus, and Scartella cristata were captured at
South Padre Island with an overall mean CPUE of 46.4±68.0. Scartella cristata was clearly the dominant
blenny (Fig. 10), exhibiting an overall mean CPUE of 44.1±65.6 and monthly mean CPUE ranging from
Hypleurochilus geminatus Sc artella cristataLabrisomus nuchipinnis
Salinity Temperature
Fig. 9. Blenny catch pe r unit effort (CPUE), salinity (ppt) and water tempera ture (C) at the South Jetty in Port Aransas, TX during May 2000 through August 2001. Hypsoblennius hentz is not shown in this figure. It was captured in May 2000 with aCPUE of 0.78 individuala /hour.
24
21
18
15
12
9
6
3
0 0
5
10
15
20
25
30
35
40
CPU
E (#
of b
lenn
ies/
net-
hour
)Salinity (ppt) and Tem
perature (C)
75.3 69.1 1 02.5 141.9 28.6
NO
EF
FOR
T
MA
Y
JUN
JUL
AU
G
SEP
OC
T
DE
C
NO
V
JAN
FEB
MA
R
AP
R
MA
Y
JUN
JUL
AUG
2000 2001
30
1.7 to 237.7. CPUE did not differ significantly (p=0.882) from Gulf side (station 4: 48.0±67.7) to the
channel side (station 5: 53.5±82.4) of the jetty. It peaked in summer and early fall then declined during
winter (Fig. 10). Labrisomus nuchipinnis’ monthly mean CPUE ranged from 0 to 6.0 with an overall
mean CPUE of 1.7±1.9. No significant difference (p=0.69) was found between its overall mean CPUE on
the Gulf side (1.1±2.3) and that on the channel side (1.9±1.8). CPUE for this species peaked in mid to late
summer and declined through fall (Fig. 10). Hypleurochilus geminatus, caught at South Padre Island only
in spring-early summer of 2001, exhibited a relatively low overall mean CPUE (0.7±2.0) with monthly
catch rates ranging from 0 to 9.6.
Size Structure
Total length (TL) of Scartella cristata captured ranged from 8 to 115 mm with site means at
Galveston, Port Aransas and South Padre Island being 51.9±22.3, 36.1±15.9, and 36.3±15.9 mm,
respectively (Table 3, Fig. 11). Mean TL of S. cristata in Galveston was significantly larger than that
from South Padre Island (p<0.001) despite the largest individuals being captured at South Padre (115 mm
TL) and Port Aransas (p<0.001). This species’ mean TL increased through the winter but declined
suddenly with the recruitment of young of year appearance of new recruits in early spring (Fig. 12).
Nonetheless, individuals in the 0-10 and 11-20 mm size classes were captured less frequently at Galveston
than at other sites (Appendix A).
Species n mean TL (mm) n mean TL (mm) n mean TL (mm)Labrisomus nuchipinnis 0 9 59.00 80 60.49
Hypleurochilus geminatus 199 37.49 65 40.94 24 22.17Hypsoblennius hentz 0 6 25.83 0
Hypsoblennius ionthas 59 26.41 0 0Scartella cristata 194 51.93 1867 36.08 2052 36.28
Galveston Port Aransas South Padre Island
Table 3. Number and mean total lengths (TL) of individuals representing five blenny specie s captured at Galveston, Port Aransas, and South Padre Island, TX during May 2000 through August 2001.
31
Hypleurochilus geminatus ranged from 15 to 94 mm TL with the largest size classes (81-90 and
91-100 mm) collected only in Galveston (Appendix A). Overall mean TL for conspecifics from
Galveston, Port Aransas, and South Padre Island was 37.49, 40.94, and 22.17 mm, respectively (Table 3,
Fig. 13). Port Aransas yielded the largest individuals (Galveston: t=-3.344, p=0.001; South Padre Island:
t=6.880, p<0.001). This species’ mean monthly TL generally increased through winter and declined as
younger individuals recruited to the jetties in early spring (Fig. 12). An exception to this trend occurred at
South Padre Island where H. geminatus was encountered only in spring and early summer 2001 as small,
immature (<40 mm TL) individuals.
Although Labrisomus nuchipinnis was only captured once in the samples from September to
April, anglers consistently captured large individuals (>100 mm TL) at Port Aransas and South Padre
Island throughout the study. Angler-caught conspecifics were not included in statistical analysis but these
captures indicate L. nuchipinnis was present on the middle and lower coast throughout the year.
Labrisomus nuchipinnis, ranging in size from 22 to 167 mm TL, displayed no significant size difference
(p=0.879) between constituents taken at Port Aransas (59.00 mm) and South Padre Island (60.49 mm)
(Table 3, Fig. 14). Monthly mean TL of L. nuchipinnis remained relatively constant during this study
F ig. 11. Me an total length (TL) and its standard error for Scartella cristata at Galv eston, Port Aransas, and South Padre Island, TX from Ma y 2000 to August 2001. n represents the number of indiv iduals sampled from each location.
TL (m
m)
Sou th Padre IslandPort AransasGalveston0
60
50
40
30
20
10
n=195
n=1867 n=2052
32
(Fig. 12) as a result of no recruitment pulses. Individuals less than 40 mm TL were captured only during
summer (Appendix A).
MA
Y
JUN
JUL
AU
G
SEP
OC
T
DE
C
NO
V
JAN
FEB
MA
R
AP
R
MA
Y
JUN
JUL
AU
G
2000 2001Hypleurochilus
geminatusHypsoblennius
ionthasS carte llacr istata
Labrisomus nuchipinnis
Hypsoblenni us hentz
Fig. 12. Monthly mean total length (TL) and its standard error for five blennyspecies at Galveston (G), Port Aransa s (PA) and South Padre Island (SPI), TX from May 2000 to August 2001.
0
25
175
150
125
100
75
50
2000
25
175
150
125
100
75
50
200NO
EFF
OR
TNO
EFF
OR
T
NO
EFF
OR
T
NO
EF
FOR
T
0
25
175
150
125
100
75
50
200G
PA
SPI
TL (m
m)
33
Hypsoblennius hentz and Hypsoblennius ionthas did not exhibit seasonal size trends. Both
species were captured across relatively narrow size ranges and at similar mean TL (H. hentz: 22-31 mm
TL, mean=25.83 mm; H. ionthas: 12-50 mm TL, mean=26.41 mm) (Table 3, Fig. 12). Length frequency
distributions indicated relatively strong recruitment of H. ionthas at Galveston in late spring of 2000, with
those cohorts persisting through August and virtually absent thereafter (Fig. 12, Appendix A).
Fig. 13. Mean total length (TL) and its standard error for Hypleurochilus geminatus at Galveston, Port Aransas, and SouthPadre Island, TX from May 2000 to August 2001. n represents the number of individuals sampled from each location.
TL (m
m)
South Padre IslandPort AransasGalveston0
50
40
30
20
10
n=199
n=65
n=24
34
Species Diversity and Evenness
Monthly mean blenny diversity ( H ′ ) was 0.23±0.02, 0.11±0.11, and 0.09±0.08 for Galveston,
Port Aransas, and South Padre Island, respectively (Fig. 15). Galveston had significantly higher diversity
than did other sites (p=0.001). Monthly diversity never exceeded 0.4 at any site and was never greater
than 0.22 at South Padre Island. Although highly variable, diversity generally peaked in late spring,
declined through summer and fall, and increased by late winter. This pattern was best defined at Port
Aransas (Fig. 16).
Evenness values of 0.64±0.37, 0.29±0.30, and 0.30±0.26 were observed for Galveston, Port
Aransas, and South Padre Island respectively (Fig. 15). Galveston also exhibited a significantly higher
evenness value (p=0.001) than did other sites. Evenness at Galveston remained fairly high throughout
summer and fall (0.60-0.98), declined dramatically in winter and was relatively low (0.00-0.40) through
spring. Evenness at Port Aransas mirrored species diversity by peaking in spring and diminishing through
fall. The only pattern in species evenness at South Padre Island was values in 2000 were considerably
higher than those in 2001 (Fig. 16).
Fig. 14. Mean total length and its standa rd error for Labris omus nuchipinnis at Galveston, Port Ara nsas, and South Padre Island, TX from May 2000 to August 2001. n represents the number of individuals sampled from each location.
TL (m
m)
0
60
50
40
30
20
10
South Padre IslandPort AransasGalveston
n=0
n=9
n=8070
80
35
Galveston Port Aransas South Padre Island
0.7
0.8
0.5
0.6
0.4
0.3
0.1
0.2
0
Fig. 15. Mean monthly Shannon-Wiener diversity index (H’) and species evenness (J’) and their standard errors forblenny assemblages at Galveston, Port Aransas, and South Padre Island, TX from May 2000 to August 2001.
H’ J’H’ a
nd J’ i
ndex
val
ue
Estimate of Scartella cristata Population Density
Scartella cristata was chosen for mark recapture studies because of its dominance and apparent
high population density on Texas jetties. Three complete mark-recapture collections were performed at
Port Aransas in June 2001 and were the basis for population estimates ranging from 158 to
281individuals/linear meter of jetty. These estimates yielded an overall mean of 214 individuals/linear
meter of jetty and standard error of 36. CPUE data generated at the same station concurrent to mark
recapture experiments and converted to number of individuals per linear meter of jetty estimated mean
density to be 11.2 with a standard error of 3.2—approximately 5.2% of the density estimated through
mark-recapture trials.
Age Structure of Scartella cristata Along the Texas Coast
Microstructure analysis of otoliths indicated Scartella cristata ranged in age from 47 (12 mm TL)
to 466 days (78 mm TL). Mean age-at-capture for Galveston, Port Aransas, and South Padre Island
individuals was 213.0±114.1, 131.6±81.7, and 132.7±81.7 days, respectively. These means differed
36
statistically among locations (p<0.001) with Galveston constituents being significantly older (p<0.001).
Fig. 16. Monthly mean Shannon Wiener diversity index (H’) a nd species evenness(J’) and their standard errors for blenny assemblages at Galveston (G), Port Aransas(PA) and South Padre Island (SPI), TX from May 20 00 to August 2001.
H’ J’
MA
Y
JUN
JUL
AU
G
SE
P
OC
T
DE
C
NO
V
JAN
FEB
MA
R
AP
R
MA
Y
JUN
JUL
AUG
2000 2001
0
0.2
0.4
0.6
0.8
1.0
0
0.2
0.4
0.6
0.8
1.0
0
0.2
0.4
0.6
0.8
1.0
G
PA
SPI
NO
EF
FOR
TN
O E
FFO
RT
NO
EF
FOR
T
NO
EFF
OR
T
H’a
nd J’i
ndex
val
ue
37
Mean age of individuals from the middle and lower coast was statistically similar (p=0.91).
Hatch-date distributions were generated for the three sites using age-length keys. While Scartella
cristata hatch throughout the year on the Texas coast, 48.2% of hatchings occurred between January and
March with an additional 29.9% taking place in April and May (Fig.17). The majority of individuals
(67.5%) captured in Galveston hatched between January and May (Fig. 18) with activity peaking in
January and March. Hatch-date distributions were more protracted in Port Aransas, lasting from January
to early July and peaking between April and June (Fig. 19). South Padre Island was the site of year-round,
low level hatching activity that peaked October to March (Fig. 20).
Scartella cristata grew at a rate of 0.25 (r2=0.69), 0.26 (r2=0.51), and 0.20 (r2=0.34) mm/day at
Galveston, Port Aransas, and South Padre Island, respectively (Fig. 21). Growth rate among sites was
statistically similar (p=0.252) and yielded a composite value of 0.2 (r2=0.44) mm/day.
0
5
1 0
15
20
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
% o
f ind
ivid
uals
Fig. 17. Pooled hatch date distribution of Scartella cristata collected from Galveston, Port Aransas, and South Padre Is land, TX and colle cted between July 2000 and August 2001.
38
Fig. 18. Hatch date distribution of Scartella cristata collected from Galveston, TXbetween May 2000 and August 2001. No estimates of mortality were incorporated intothis dataset. Only individuals whose age was calculated at or less than 270 days wereused to generate this distribution due to difficulty in reading daily growth incrementsbeyond that age.
3.0
2.4
1.8
1.2
0.6
0
1999n=6
2000n=96
2001n=60
% O
F IN
DIV
IDU
ALS 3.0
2.4
1.8
1.2
0.6
0
JAN
FEBMAR
APRMAY
JUN
JUL
AUGSEP
NOVDEC
OCT
3.0
2.4
1.8
1.2
0.6
0
Date of first sample
Date of last sample
39
1999n=52
2000n=979
2001n=710
2.5
2.0
1.5
1.0
0.5
0
Fig. 19. Hatch date distribution of Scartella cristata collected from Port Aransas, TXbetween May 2000 and August 2001. No estimates of mortality were incorporated intothis dataset. Only individuals whose age was calculated at or less than 270 days wereused to generate this distribution due to difficulty in reading daily growth incrementsbeyond that age.
% O
F IN
DIV
IDU
ALS
JAN
FEBMAR
APRMAY
JUN
JUL
AUGSEP
NOVDEC
OCT
2.5
2.0
1.5
1.0
0.5
02.5
2.0
1.5
1.0
0.5
0
Date of first sample
Date of last sample
40
1999n=17
2000n=524
2001n=1374
Fig. 20. Hatch date distribution of Scartella cristata collected from South PadreIsland, TX between July 2000 and August 2001. No estimates of mortality wereincorporated into this dataset. Only individuals whose age was calculated at or lessthan 270 days were used to generate this distribution due to difficulty in reading dailygrowth increments beyond that age.
% O
F IN
DIV
IDU
ALS
3.0
2.4
1.8
1.2
0.6
0
JAN
FEBMAR
APRMAY
JUN
JUL
AUGSEP
NOVDEC
OCT
3.0
2.4
1.8
1.2
0.6
0
3.0
2.4
1.8
1.2
0.6
0
Date of first sample
Date of last sample
41
Genetic Structure and Origins of Scartella cristata on the Texas Coast
Comparison of mtDNA D-loop sequences performed for Scartella cristata revealed 30
aplotypes distinguished by 22 variable sites. Polymorphic sites corresponded to 11 transitions, 10
transversions, and a single nucleotide attributable to an insertion/deletion event. Sequences for each
haplotype characterized appear in Appendix B. Haplotype diversity (h) within each sample was high,
being 0.833, 0.805, 0.959, and 0.977 at Florida, Galveston, Port Aransas, and South Padre Island,
100
80
60
40
20
00 50 100 150 200 250 300
TL (m
m)
Age (days)Fig. 21. Age-length relationship for Scartella cristata captured at Galveston, Port Aransas, and South Padre Island, TX jetties from May through September 2000. Individuals older than 270 days are excluded from this analysis due to difficulty in reading daily growth increments beyond that age .
SLOPE INTERCEPT R2
Galveston 0.246 8.70 0.69Port Aransa s 0.255 -3.63 0.51South Padre I sland 0.146 17.84 0.34Pooled 0.195 10.42 0.44
LOCATION n h πFlorida 9 0.833 0.004Galveston 20 0.805 0.005Port Aransas 19 0.959 0.010South Padre Island 19 0.977 0.011
Table 4. Sample size, haplotype diversity (h) , and nucleotide dive rsity (p) for Scartella cristata from sample sites in the Gulf of Mexico.
42
respectively (Table 4). Nucleotide diversity (π) varied from low levels in Florida (0.004) and Galveston
(0.005) samples to more intermediate levels in those from Port Aransas (0.010) and South Padre Island
(0.011) (Table 4). Most haplotypes represented in Florida and Galveston samples were shared between
the two sites, whereas more than half of those found in Port Aransas and South Padre Island samples were
unique to either site (Table 5). Only one haplotype (D) was shared across all four sites (Table 5). The
Florida sample was dominated by one haplotype (B) accounting for 44% of its constituents. Three closely
Haplotype Florida Galveston Port Aransas South PadreA 1 4 2B 4 7 1C 1 1D 1 4 1 1E 5 2 3F 1 1G 1H 1 1I 1J 1K 1L 1M 1N 1O 1 1P 1Q 1R 1S 1T 1 1U 1V 1W 1X 1Y 1Z 1
AA 1AB 1AC 1AD 1
Table 5. Haplotype distribution for Scartella cristata ba sed on 380 base pairs of the D-loop re gion from Florida, Galve ston, Port Aransas, and South Padre Isla nd, TX. Haplotypes are designated by letters in the first column.
43
elated haplotypes (B, D, E) accounted for 80% of the individuals in the Galveston sample whereas no
single haplotype was dominant at Port Aransas or South Padre Island (Table 5, Fig. 22, 23).
There was little genetic distance among samples (Fig. 24). Genetic distances ranged from 0.005
between Florida-Galveston to 0.011 between Galveston-Port Aransas and Port Aransas-South Padre Island
(Table 6) and averaged 0.009 (S.E.=0.003). Mantel’s test generated a correlation coefficient of -0.217, to
indicate no significant relationship (p≥0.658) between genetic distance and geographic distance. AMOVA
revealed that samples from Florida and Galveston were statistically similar (p>0.58) as were Port Aransas
and South Padre Island (p>0.23). No such similarity (p≤0.01) was found between Florida or Galveston
samples and those of Port Aransas and South Padre Island (Table 6). While the majority of variance
(80%) could be accounted for within samples, a significant portion (20%) was attributed to among group
variance (ΦST) corresponding to the differentiation between Florida-Galveston and Port Aransas-South
Padre Island. The ΦST values, in ranging from –0.24 to 0.30, indicated low levels of population structure
(Table 6). Number of migrants per generation (Nm) was high between Florida-Galveston (∞) and Port
Aransas-South Padre Island (55.6) but an order of magnitude lower among other site comparisons that
ranged from 3.8 for Galveston-South Padre Island to 1.2 between Florida-Port Aransas (Table 6). This
gene flow did not prevent Florida and Galveston samples from exhibiting a haplotype frequency distinct
from those in south Texas (Fig. 22, 23).
Table 6. Genetic isolation of Scartella cristata at Gulf of Mexico study sites relative to geographic distance between sites.Linear distances (km) between pairs of study sites, Tamura-Nei genetic distance (d), the among-group component of geneticvariation (ΦST), a statistical test based on haplotype frequency shifts and an estimate of gene flow in terms of the number ofmigrants per generation (Nm) are presented.
LOCATIONS DISTANCE (km) d F ST EXACT TEST N m
Florida-Galveston 689 0.005 -0.24 (p >0.58) 8Florida-Port Aransas 763 0.011 0.30 (p <0.01) 1.2Florida-South Padre Island 948 0.010 0.17 (p <0.01) 2.4Galveston-Port Aransas 272 0.010 0.24 (p <0.01) 1.6Galveston-South Padre Island 416 0.009 0.12 (p <0.01) 3.8Port Aransas-South Padre Island 196 0.011 0.09 (p >0.23) 55.6
Mismatch distributions for Scartella cristata sequences tended to visually resemble the Poisson
distribution at all locations (Fig. 25) while chi-square analysis indicated significant differences from this
expected distribution (Florida: p=0.003; Galveston: p=0.007; Port Aransas: p=0.029; South Padre Island:
p=0.018). This suggests that the effective population size of Scartella cristata is at long-term equilibrium
in the Gulf.
44
FloridaG
alvestonPort A
ransasSouth Padre Island
Fig. 22. Com
posite haplotype distribution of mtD
NA
D-loop sequences of Scartella cristata from
Florida, Galveston, Port
Aransas and South Padre Island, TX. D
iameter of each circle represents frequency of occurrence of that haplotype w
ithin asite. The division of each circle represents percent of individuals from
a particular site exhibiting that haplotype. Empty
circles represent hypothesized intermediates. A
lternative linkages are represented by dotted lines.
AA
I
V
X
SJR AB
G
L Q K
UM
N
P
AD
AC
Y
H
D
W Z FC
B
OAE
T
12
7-810
12n=
45
D
B
N
M P
TE
KQL
J A O
R
S
C Y w Z AA
D
TA VUAC
E
O
AB
X
AD
Fig. 23. Haplotype distributions of mtDNA D-loop sequences of Scartella cristatafrom Florida, Glaveston, Port Aransas and South Padre Island, TX. Empty circlesrepresent hypothesized intermediates. Alternative linkages are represented asdotted lines.
Port Aransas South PadreIslandn=19
n=19
A
H
D C
B
F
Floridan=9
B
E
G
DF
IH
Galvestonn=20
46
Fig. 24. Genetic distances between Scartella cristata from Florida, Galveston, PortAransas, and South Padre Island, TX.
FloridaGalvestonPort AransasSouth Padre Island
0.005
47
DISCUSSION AND CONCLUSION
Structure and Composition of Blenny Assemblages on Texas Jetties
Variability in Species Composition
The data suggests that blenny assemblages are different in species composition, diversity and
evenness among the locations sampled. Assemblages on the upper Texas coast at Galveston were
dominated to similar extents by Hypleurochilus geminatus and Scartella cristata. Hypsoblennius ionthas
also occurred sporadically on these jetties. Four blenny species were captured on jetties from the middle
Texas coast at Port Aransas. Scartella cristata was the dominant species, but H. geminatus and
Labrisomus nuchipinnis were taken regularly. Hypsoblennius hentz was a fourth but rare inhabitant of
jetties in this area. Differences between Port Aransas stations 2 and 3 suggest that these sites may not
encompass the range of variability blenny assemblages encounter on a jetty. Despite exhibiting similar
Fig. 25. Mis match distributions(histogram) and their expected Poisson distribution for mtDNA D-loop sequence s of Scartella crista ta from Florida, Galveston, Port Aransas , and South Padre Island, TX.
Floridan=9
45
30
15
0 4 8 121 2 3 5 6 7 9 10 1 1 130
Galvestonn=20
45
3 0
15
0 4 8 121 2 3 5 6 7 9 10 11 130
Port Aransasn=19
45
30
15
0 4 8 121 2 3 5 6 7 9 10 11 130
South Pa dre Islandn=19
45
30
15
0 4 8 121 2 3 5 6 7 9 10 11 130
Number of Pairwise Differences
Freq
uenc
y
48
diversity and evenness values, Port Aransas and lower Texas coast at South Padre Island yielded blenny
assemblages with distinct species composition. The blenny assemblages at South Padre Island were
dominated by S. cristata. Labrisomus nuchipinnis occurred with greater frequency here than on the
middle Texas coast. Hypeurochilus geminatus was rarely encountered and only as small individuals (<40
mm TL) thus suggesting its recruitment to lower coast jetties is infrequent and short-term. With the
exception of Hypsoblennius ionthas in Galveston, Hypsoblennius hentz in Port Aransas, and
Hypleurochilus geminatus at South Padre Island, species composition was predictable and relatively stable
at a given location.
Blenny assemblages on Texas jetties also demonstrated temporal variability. Blenny species
underwent seasonal shifts in relative abundance at all three study areas. Although numerous factors could
account for this variability, the ultimate cause is likely seasonal temperature fluctuations and differential
thermal preferences or tolerances of constituent species. Thermal preferences/tolerances have been
demonstrated to be important in the determining the composition and structure of fish communities in
intertidal habitats (Zander et al. 1999, Davis 2000, Faria and Almada 2001). For example, CPUE of
Scartella cristata, typically considered a tropical/subtropical species (Hoese and Moore 1998), peaked in
early to mid summer while the maximum CPUE of a more temperate counterpart, Hypleurochilus
geminatus, occurred in mid to late spring. Spring and summer peaks of H. geminatus and S. cristata
respectively, exhibited higher CPUE than did other seasons due to influx of new recruits to Texas jetties as
illustrated by both hatch-date analysis and length-frequency data. This pattern suggests a stable adult
component of blenny assemblages with observed variability due to the timing of spawning and subsequent
recruitment, which is often linked to temperature (Clarke 1979, Faria and Almada 1999). Faria and
Almada (1999, 2001) in Portugal and Davis (2000) in California found that relative abundance of similar
species in rocky intertidal fish assemblages was closely tied to temperature.
The majority of individuals captured during these peaks in CPUE were small, new recruits while
the relative numbers of adults remained constant, this pattern has also been described in Hypsoblennius
ionthas populations in Mobile Bay (Clarke 1979). Many rocky shore fishes exhibit little relationship
between the variability of their recruitment pulses and adult population size, despite significant mortality
49
during early life stages of these fishes. Studies by Hunte and Côté (1989) on redlip blennies
(Ophioblennius atlanticus) in the Caribbean, Pfister (1996) on intertidal sculpins (Clinocottus spp. and
Oligocottus spp.) in the Pacific northwest, and Ruchon et al. (1998) on the blenny Lipophrys pavo in the
Mediterranean indicate that post-recruitment processes such as competition operate independent of those
occurring in the plankton to impact the adult population (Hunte and Côté 1989, Jones 1991, Pfister 1996,
Ruchon et al. 1998).
Blenny catches on Texas jetties tended to vary with changes in water temperature; however,
selectivity of sampling gear and blenny behavior during winter months may have accounted for temporal
variability in CPUE. For example, blenny CPUE declined during winter 2000-01 from higher fall and
spring levels at all three sites. It is likely that winter conditions (i.e. cold temperatures and rough surf)
result in blenny mortality (Santos and Nash 1996) thereby impacting CPUE; however, blennies also
probably have behavioral responses to low temperatures (Murdy et al. 1997). Responses such as reduced
activity levels or moving to deeper, more thermally stable water, a pattern seen in many fish (Neill 1979),
may coincidentally enhance gear avoidance. Higher CPUEs in 2001 than in 2000 may have resulted from
increased proficiency and experience with collection techniques. For example, CPUE at South Padre
Island increased dramatically in May 2001 due to the discovery of large numbers of blennies in the
supralittoral fringe. Previous collections had not sampled this area because it was not expected that
blennies would be out of the water.
Salinity and turbidity did not seem to influence monthly blenny CPUE. Blenny CPUE during
low beachfront salinities (15‰) at Galveston following Tropical Storm Alison in June 2001 was not lower
compared to June 2000. Low turbidity was anticipated to enhance gear avoidance at Port Aransas and
South Padre Island; however, no discernable effect was noted. CPUE on the middle and lower coast was
consistently higher than in more turbid waters on the upper coast.
Results of the present study appear to indicate that blenny assemblages on the Texas coast could
be divided into three distinct groups based on regional species composition, species diversity, and
evenness with these distinctions being driven primarily by temperature. However, expansion of this study
to other jetty systems in Texas would enable a better assessment of the distinctiveness of blenny
50
assemblages and their habitat requirements across the upper, middle and lower Texas coast and to what
degree Galveston, Port Aransas, and South Padre Island are representative of these features. Expansion to
cover a greater amount of potential blenny habitat would allow assessment of how effective stations used
in the present study represent Texas’ jetty system as a whole.
Size Structure
Total length of Scartella cristata and Hypleurochilus geminatus was significantly higher on
jetties on the upper and middle Texas coast than on those of the lower coast. Mean total length was
highest at Port Aransas in the case of H. geminatus and at Galveston for S. cristata. There are several
possible explanations for this pattern in S. cristata. The total n for the Galveston collections was an order
of magnitude lower than that of the other two sites; therefore, any bias toward larger individuals would
have a greater impact on the mean. It is also possible density-dependent effects, such as competition for
food or shelter, might be operating at a reduced level, thus allowing S. cristata to reach a larger size at
Galveston because the density was lower than that at the other two sites. The amount of shelter available
to smaller individuals may be limiting and thereby favor larger individuals because the structural
complexity of the habitat at Galveston was less than that at the other sites. Shelter availability and size
was found to be a determining factor in the size structure of blenny populations in rocky littoral zones of
the western Mediterranean (Patzner 1999), the rocky intertidal zone of California (Stephens et al. 1970),
and on oyster reefs along the east coast of the United States (Swearer and Phillips and Swears 1979,
Crabtree and Middaugh 1982). The precise role of rugosity on the composition and structure of blenny
assemblages is not conclusive. The location with the lowest structural complexity, Galveston, exhibited
the highest species diversity, evenness, and mean TL. There also is the possibility that large S. cristata
were present at Port Aransas and South Padre Island but were concentrated in deeper reaches of the jetty
not sampled during this study.
Stability of Blenny Assmblages
How stable is the structure and composition of blenny assemblages on Texas jetties? The only
other studies that documented blenny assemblages on jetties focused on newly constructed jetties in the
Florida panhandle (Hastings 1979) and South Carolina (Van Dolah et al. 1984, 1987) Blenny assemblages
51
on these jetties exhibited a fair degree of stability. Hypleurochilus geminatus was the first blenny to
recruit to both locales and although other species (Hypsoblennius spp.) eventually arrived during these
studies, H. geminatus never relinquished dominance (Hastings 1979, Van Dolah et al. 1984, 1987). While
this study is consistent with the findings of Hastings (1979) and Van Dolah et al. (1984, 1987) indicating
that blenny assemblages are relatively stable, long-term surveys of a larger percentage of Texas jetties
with an ecosystem focus should be undertaken. Of particular importance would be establishing sampling
stations across the entire reach and depth of the jetty habitat and incorporating complete faunal and floral
surveys of these habitats. The blenny species on Texas jetties may be a series of metapopulations
undergoing local extinctions and re-colonizations on a regular basis and acting as sources or sinks for each
other (Pulliam 1988). The sampling design of this study left large expanses of the jetty uncharacterized
(deep water, end of the jetty, intermediate stations) from which to resolve uncertainties regarding temporal
and spatial variability. The present study made no attempt to characterize other biotic components of the
jetty community. Future studies need to characterize changes in the fauna and flora of Texas jetties.
Population dynamics of organisms such as epilithic algae and invertebrates upon which blennies depend
for food and shelter or potential predators such as birds and larger fishes could impact the composition of
blenny assemblages on Texas jetties. Kevern et al. (1985) reported an “explosive” colonization of
sculpins on a newly constructed artificial reef in Lake Michigan that eventually declined due to shifts in
the population structure of predators that fed on sculpins. Concurrent shifts in the size structure of local
sculpin populations were also observed (Kevern et al. 1985). Little is known about predators and prey of
blennies and thus changes in their populations may precipitate major shifts in blenny assemblage structure
without apparent cause.
Differences in CPUE, species composition, size structure, diversity, and evenness may be due to
this study’s experimental design. Due to safety concerns, sampling frequently was not conducted evenly
between stations at study sites on a monthly basis. The significant difference in CPUE and species
composition between stations 2 and 3 at Port Aransas is also problematic, indicating potential differences
between microhabitats and suggesting that sampling was not representative of the entire jetty. As
previously mentioned, increasing the number of stations at a study site to include areas not covered in this
52
study as well as increasing the number of study sites would alleviate many of these problems. It would
also be desirable to establish paired stations (i.e. on the north and south jetty at each site) enabling better
replication of sampling effort.
Age and Growth of Scartella cristata on Texas Jetties
Age and Growth
Scartella cristata appears to be a fast growing, short-lived resident on Texas jetties. It was found
to grow at 0.2 mm/day, live about 1.5 years, and spawn from January to June. While no previous work
has been published on age and growth of S. cristata, Eyeberg (1984) found similar results in a South
African congener, Scartella emarginata. The latter grows quickly, up to 0.26 mm/day under laboratory
conditions, reaches sexual maturity at 36 mm total length, rarely lives past 2 years, and spawns year round
(Eyeberg 1984). This pattern is seen in small, short-lived reef fishes such as gobies (Kritzer 2002);
however, whether it holds true for all subtropical/tropical blenniids or only for the Genus Scartella is
unclear. Nonetheless, temperate blennies exhibit a life history pattern almost completely opposite that of
Scartella. Hypsoblennius species along the California coast are long-lived (7+ years) and grow quickly
(0.12 mm/day) for their first year prior to slowing (0.03 mm/day) considerably (Stephens et al. 1970).
Blennius gattorugine and Blennius pholis live up to 9 years in Ireland, grow quickly (no rate reported) for
the first 2 years, then slow considerably (Dunne and Byrne 1979). These temperate species also spawned
within discrete seasons, usually spring through early summer (Stephens et al. 1970, Dunne and Byrne
1979). Estuarine species of blennies also appear to exhibit a different life history pattern. Hypsoblennius
hentz was found to grow at over double the rate (0.5 mm/day) of Scartella in estuaries of the mid-Atlantic
Bight (Able and Fahay 1998). This may be due to estuarine species of Hypsoblennius being longer-lived
and slower to mature (Clarke 1979) than Scartella, thus allowing them to dedicate more energy toward
somatic growth.
Growth rates of Scartella cristata appear consistent with those of S. emarginata, the only
published value for Scartella; however, estimated size-at-hatching is somewhat problematic because at
10.42 mm it greatly exceeds published accounts of hatch sizes for Blenniidae; Chasmodes
bosquianus=3.56-3.78 mm (Fritzsche 1978), Hypsoblennius hentz=2.6-2.8 (Fritzsche 1978),
53
Hypsoblennius ionthas=2.82 mm (Clarke 1979), Ophioblennius atlanticus=1.3-1.5 mm (Labell and
Nursall 1985), Scartella emarginata=3.5 mm (Eyeberg 1984). However, published estimates of size-at-
hatching were all acquired by direct observation while current estimates for S. cristata were inferred from
the regression model. This difference illustrates one limitation in using size-at-age relationships to
estimate hatch size. In addition, y-intercept estimates in this study are misleading due to the lack of small
specimens examined.
Patterns of Dominance
Four blenniid species—Hypleurochilus geminatus, Hypsoblennius hentz, Hypsoblennius ionthas,
and Scartella cristata—potentially recruit to Texas jetties but their coexistence at any given time is rare.
Post-recruitment resource partitioning on both large and small temporal and spatial scales allows blenniid
to coexist and leads to assemblage stability (Stephens et al. 1970, Clarke 1989). Differences in
interspecific dietary preferences (Eyberg 1984, O’Farrel and Fives 1990), dietary preferences between
sexes or age classes within a species (Clarke 1979, Osenberg et al. 1992, Goncalves and Almada 1997),
metabolic rates (Clarke 1992), or feeding morphology (Lindquist and Dillman 1986) may be significant
factors isolating species into niches and thereby determining the composition of blenny assemblages.
Shelter availability (Stephens et al. 1970, Phillips and Swears 1979, Crabtree and Middaugh 1982),
territoriality (Stephens et al. 1970, Goncalves and Almada 1998, Wilson 2000), water temperature
preferences (Zander et al. 1999), and recruitment patterns are other influences on assemblage structure.
These interspecific and intraspecific interactions plus those between individuals and their habitats are key
to predicting changes in population structure (Jones 1991). Because these blenniid species share similar
habitat requirements and differ only slightly in dietary requirements (Lindquist and Dillaman 1986), it is
much more common for assemblages to be dominated by one or two species.
Scartella cristata is the dominant blenniid species on the Texas jetties sampled during this study
regardless of local conditions. This is contrary to previous accounts by Hoese and Moore (1998) who
assigned dominant status to Hypleurochilus geminatus. These previous accounts may have been based
upon incomplete or inaccurate data, as there is little published literature describing ichthyofauna of Texas
jetties. However, it is possible blenny assemblages have undergone major shifts in species composition as
54
the biotic community continues to evolve on Texas jetties. Other studies on Florida and South Carolina
jetties have noted dominance of H. geminatus (Hastings 1979, Van Dolah 1984, 1987), but may not have
been sufficient in duration to observe the colonization of S. cristata. The latter species appears to be
tolerant of the entire spectrum of environmental conditions (temperature, salinity, turbidity, and habitat
complexity) along the Texas coast. A lack of more detailed information on the biology of other
constituent species for comparison, particularly H. geminatus, makes it difficult to explain why S. cristata
is so successful on Texas jetties.
Scartella cristata’s total dominance of other blenniids through competitive exclusion may be
possible only under the environmental conditions and habitat quality of the central and lower Texas coast.
Woodland (1999) found this type of exclusion and dominance based on differences in local condition
demonstrated by the Family Signidae, a family of herbivorous reef fishes in the western Pacific.
Conversely, the more temperate species such as Hypleurochilus geminatus may not compete as well as
Scartella cristata in the more subtropical waters of the central and lower Texas coast. Clarke (1989, 1992)
found that the higher metabolic rate of Acanthemblemaria spinosa, a tube dwelling chaenopsid blenny,
allowed it to displace a congener, Acanthemblemaria aspera, from preferred, higher quality habitat and
facilitating a higher growth rate in A. spinosa. A more tropical species, such as S. cristata, may have a
higher metabolic rate giving it an advantage in agonistic interactions as seen in A. spinosa (Clarke 1992).
Differential growth rates between species may be an important underlying explanation for why
certain species dominate (Jones 1991) or a result of competive interactions between species (Clarke 1992).
With growth, fishes typically decrease their vulnerability to predation, increase their fecundity, and, in
territorial species such as blennies, increase the size of territory they can or need to defend (Stephens et al.
1970, Phillips and Swears 1979, Jones 1991, Goncalves and Almada 1998). A blenniid species reaching a
large size quicker than a competing species has the edge in not only holding more territory, but also
producing more offspring. Consequently, a faster growing species has the potential to exclude a slower
growing species from a given area over time. Further work with additional blenniid species, particularly
Hypleurochilus geminatus, will determine if this is the case on Texas jetties.
The Genetic Structure of Scartella cristata on Texas Jetties
55
Scartella cristata is a wide-ranging species occurring on nearshore reefs and rocky shores
throughout the tropical Atlantic, Caribbean, Gulf of Mexico, and Mediterranean. The Texas Gulf coast
likely represented a gap in the distribution of this species due to a lack of suitable habitat. With initiation
of jetty construction in Texas during the 1880’s, S. cristata larvae that historically would pass the Texas
coast found new habitat to colonize in state waters. The genetic structure of local populations on Texas
jetties reflects the history of this colonization. Haplotype diversity (h) of S. cristata across Florida,
Galveston, Port Aransas, and South Padre Island was high; however, nucleotide diversity (π) was low to
moderate. While these results indicate a large number of different haplotypes exist in the S. cristata
population, low nucleotide diversity suggests they are closely related and effective population size is
relatively small. This relationship between h and π is consistent with findings by Muss et al. (2001) for
another wide ranging blenniid, Ophioblennius atlanticus, and appears to be a common theme among many
marine fishes (Palumbi 1994, Grant and Bowen 1998).
Both haplotype and nucleotide diversity were greater for conspecifics from the middle and lower
Texas coast than that for their upper coast and Florida cohorts. This suggests that the source population of
Scartella cristata for Port Aransas and South Padre Island is more diverse and possibly older or larger than
that for Galveston and Florida. Whether or not Florida is the source population for Galveston cannot be
answered definitively based on the limited number of sample sites and small number of individuals from
the former. It is clear that if Florida is not the source population for Galveston then the two share the same
origins. Similarities in haplotype distribution and among group component of variation (ΦST), low genetic
distances between sites (0.005), and high level of gene flow per generation link the two sites despite the
large geographic distance (689 km) and the Mississippi River plume that separates them. This linkage is
accomplished through predominant nearshore currents in the Gulf, which would tend to carry larvae from
east to west throughout the year (Fig. 26).
Transport of Scartella cristata larvae to Texas jetties from either Mexico or Florida is plausible.
Although not known for S. cristata, the larval duration of Hypsoblennius ionthas lasts from 6 to 8 weeks
(Clarke 1979). Longshore currents along the Texas coast range in velocity from 12 (Fox and Davis 1976)
to 21.5 cm/s (Smith 1975) under typical conditions, while larvae entrained in a boundary current such as
56
the Mexican Current can be carried at 70-100 cm/s (Sturges and Blaha 1976). These features put Texas
jetties within reach of larvae traveling from the eastern or southern Gulf or Mexico even if larval duration
is only 30 days. A small amount of one-way gene flow (Nm<4.0) from Galveston-Florida to Port Aransas
and South Padre Island may facilitated by prevailing currents (Fig. 26), but this does not appear to be the
primary source of S. cristata to these southerly sites. Current flow in the Gulf and on the Texas-Louisiana
shelf suggests the hard shores and nearshore reefs of southern Gulf or western Caribbean as a primary
Fig. 26. D irection of current flow in the Gulf of Mexico (a,c) and on the Texas -Louisiana shelf (b, d) during non summer (a, b) and summer months (c, d). Black and white tria ngles represent northerly and southerly f low, respec tively, in b a nd d. Black circles repres ent sample sites. Gulf of Mexico c urrents adapted from Britton and Morton (1989) and Texas-Louisia na shelf currents from Cho e t al. (1998).
a
c
b
d
57
source for Port Aransas and South Padre Island (Fig. 26) due to the northerly current flow during summer
on the Texas-Louisiana shelf (Cochrane and Kelly 1986, Britton and Morton 1989, Cho et al. 1999). The
middle and lower coast have similar haplotype distribution, no difference in the among group component
of variation (ΦST), and exchange a large number of migrants per generation (Nm=55.6). These similarities
suggest they share the same source population(s); however, the two sites are separated by a genetic
distance (0.011) comparable to that of most other sites (Table 6). Since mismatch distributions indicate
Port Aransas and South Padre Island samples were large enough to encompass the variability at each
locality, it seems these sites may be in the process of evolving distinct subpopulations. Overall, this study
indicates that S. cristata on Texas jetties are not yet isolated from their possible sources but are extensions
of them. This is contrary to work on red drum (Sciaenops ocellatus) and red snapper (Lutjanus
campechanus) that indicates a single population of each species within the Gulf (Gold et al. 1999, Heist
and Gold 2000, Gold et al. 2001). Comparisons of these species with Scartella cristata should be made
cautiously as both red drum and red snapper have greater potential for mixing/migrating and a greater
abundance of suitable habitat throughout the Gulf.
Even though larval blennies have high dispersal potential (Hunte and Côté 1989, Riginos 2000,
Riginos and Nachman 2001), spatial and temporal heterogeneity of coastal habitats and nearshore Gulf
waters may act to partially isolate Scartella cristata on Texas jetties both from each other and their source
populations. Palumbi (1994) predicts that larvae of marine organisms probably do not “see” the marine
environment as a homogenous habitat. The traditional interpretation is that this results in development of
genetically structured populations in areas that do not appear isolated from one another (Palumbi 1994,
Debenham et al. 2000). This does not explain low levels of genetic variation found in Ophioblennius
populations throughout the Atlantic basin (Muss et al. 2001) or in intertidal sculpins on the Pacific coast of
North America (Yoshiyama and Sassaman 1993). Both of these groups inhabit areas exhibiting spatial
and temporal heterogeneity. Studies examining population genetics of Ophioblennius atlanticus have
found that a gap in a species’ range due to lack of habitat is not sufficient to form distinct populations;
whereas, a similar gap with a barrier such as a large river is (Muss et al. 2001). A similar phenomenon
was observed in the blenny, Axoclinus nigricaudus, which exhibits distinct populations separated by less
58
than 200-km of unsuitable habitat in the Gulf of California (Riginos and Nachman 2001). The Texas coast
prior to jetty construction represented such a gap between S. cristata populations in the eastern Gulf of
Mexico and the southern Gulf/western Caribbean. This gap was a result of the mud and sand shores of
Louisiana, Texas, and northeastern Mexico and the Mississippi River plume. Establishment of suitable
habitat in the form of jetties and groins along the Texas coast seems to have removed any barriers to the
exchange of individuals between the eastern and western Gulf and raises questions regarding the role of
the Mississippi River in separating populations.
The Mississippi River plume may never have been a barrier to blenniid larval dispersal. Govoni
(1993) found that larval fishes were able to cross frontal boundaries such as the Mississippi River plume; a
finding supported by high levels of gene flow observed in this study between Florida and Galveston.
Larvae of many reef fish species, including blenniids, typically have a much broader geographical range
than do their adult counterparts (Leis 1991), which suggests the availability of suitable adult habitat plays
a major role in the genetic structure of these species. This appears to have been the case in Scartella
cristata. At least two distinct populations of S. cristata exist in the Gulf that were kept separate more by
the lack of suitable habitat in the northwestern Gulf and prevailing currents than by the Mississippi River
plume. Distribution of larvae from these populations may have overlapped along the Texas coast, but a
lack of suitable habitat prevented their interbreeding. It is unclear what impact jetty construction on the
Texas coast will have on the genetic structure of S. cristata. Jetties have facilitated these populations
mixing to a degree but current patterns appear to be an isolating mechanism by preventing homogenization
as evidenced by the distinction between Galveston and Port Aransas-South Padre Island. Further testing
of this hypothesis should be undertaken by examining recruits from multiple spawning events throughout
the year. As indicated through hatch-date analysis, S. cristata has the potential to spawn throughout the
year; however, the individuals selected for this analysis were all within the winter 1999-2000 cohort. This
means sites such as Port Aransas have the potential to undergo shifts in genetic composition with seasonal
changes in current patterns. The mismatch distributions tend to suggest otherwise, but these data may be
representative of the larger source populations and not reflect the full diversity that potentially occur in
local populations.
59
The subpopulations Scartella cristata on Texas jetties also need to be examined as
metapopulations. Blenny assemblages on Texas jetties could be sinks for their respective source
populations as described in terrestrial systems by Pulliam (1988) or they may interact together as their own
metapopulation in which an upstream jetty acts a source for a downstream sink and so on along the coast.
The data suggest this is not the case. Mismatch distributions indicate that S. cristata populations in the
Gulf have been stable for some time. This is opposite the pattern expected in populations structured as
metapopulations. The same holds true if S. cristata was recruiting to jetties from estuarine oyster reefs.
Even though it is known to occur on oyster reefs (Britton and Morton 1989, Hoese and Moore 1998), S.
cristata does not appear to be a dominant species in estuarine habitats (personal observation). Jetty
populations established from estuarine sources would be expected to exhibit a mismatch distribution
indicating exponential population growth. Data on possible interactions between jetty subpopulations and
their source population(s) are critical to understanding the population dynamics of blenny assemblages on
Texas jetties.
The genetic structure of Scartella cristata also has the potential to reveal historical patterns of
distribution of nearshore fishes in the Gulf of Mexico. There is a great deal of significance to the large
number of haplotypes present at Port Aransas and South Padre Island relative to that at Galveston and
Florida, as it is probably a result of the impact of Pleistocene glaciations. Prior to the last glaciation,
Florida was flooded allowing the movement of fishes out of the Gulf to the Atlantic coast (Briggs 1974),
but potentially reducing the amount of rocky shore habitat on the Florida peninsula. The Wisconsin
glacial period dropped sea level and temperature and probably forced the range of S. cristata south. The
rise in temperature and sea level associated with the end of the Wisconsin glaciation enabled S. cristata to
re-colonize this habitat, thus creating a founder effect (Strickberger 1996) that reduced genetic diversity of
individuals living in the eastern Gulf and subsequently the upper Texas coast. S. cristata populations
along the Mexican coast and throughout the Caribbean probably did not experience a dramatic impact
from glaciation, and were able to maintain higher genetic diversity. While this scenario is supported by
differences in haplotype diversity between locations, the disparity between the mismatch and Poisson
distribution suggests that S. cristata’s effective population sizes have been stable for an extended period of
60
time. A similar pattern has been observed in demographically distinct local populations of the parrotfish
Chlorurus sordidus from widespread locations on Australia’s Great Barrier Reef (Dudgeon et al. 2000).
Analysis of blennies from a larger number of sample sites will be needed to fully explore the plausibility
of this scenario.
Biogeography of Blennies on Texas Jetties
A transition in the species composition of blenny assemblages appears to occur on the middle
Texas coast. This area may represent a biogeographic break for several blenny species due to current
patterns and environmental tolerances of these taxa. The Texas coast receives a convergence of northward
and southward flowing longshore currents (Fig. 25). The exact location of this convergence varies by
season; it is located near Matagorda Bay in summer and near the mouth of the Rio Grande throughout the
rest of the year (Cochrane and Kelly 1986, Britton and Morton 1989, Cho et al. 1998). The Texas coast
also provides transition between subtropical and temperate climatic regimes (Britton and Morton 1989).
Two species, Labrisomus nuchipinnis and Hypleurochilus geminatus, appear to reach the limits of their
distribution on the Texas coast near Port Aransas. Failure to encounter L. nuchipinnis north of Port
Aransas conforms to previous descriptions (Springer 1958, Hoese and Moore 1998) of this tropical-
subtropical species’ range. H. geminatus, a more temperate species (Hoese and Moore 1998), was rarely
encountered south of Port Aransas. These distributional patterns may be indicative of these species’
environmental tolerances and/or probable sources of initial recruits to Texas jetties. Even though L.
nuchipinnis occur on hard shores of the eastern Gulf, they are more typically associated with warmer
waters of the Caribbean and southern Atlantic (Hoese and Moore 1998). Their observed distribution on
Texas jetties suggests that the original source population(s) is located in the southern Gulf or Caribbean.
Whether environmental conditions are favorable to this species’ colonization north of Port Aransas may be
irrelevant if prevailing current patterns prevent transport of their larvae. H. geminatus is common along
the southeastern U.S. coast (Lindquist and Chandler 1978, Hoese and Moore 1998) and is a frequent
inhabitant of Florida jetties (Hastings 1979). Based upon its distribution on Texas jetties, the most
probable source population for H. geminatus would be from the eastern Gulf of Mexico. If H. geminatus
recruits to Texas jetties originated in the southern Gulf or Caribbean then South Padre Island should host a
61
more robust population. The catch of small individuals at South Padre only during the late spring and
early summer suggests these individuals were transported from the eastern Gulf before current flow shifted
for the summer.
The distribution pattern observed for two Hypsoblennius species found on Texas jetties does not
appear to be impacted by a biogeographical break. Hypsoblennius hentz and H. ionthas are commonly
found on estuarine oyster reefs (Hubbs 1939, Clarke 1979, Smith-Vaniz 1980, Hoese and Moore 1998)
and usually are not common on Texas jetties except for newly settled individuals in the late spring/early
summer. This distributional pattern leads to the conclusion these species probably colonized jetties from
bays. It is difficult to explain why H. ionthas was virtually absent from Galveston collections in 2001
after being relatively common during spring and early summer 2000. It is possible that some
environmental condition favored a large-scale export of larvae from the bay to groins on the beachfront.
Few, if any, of these individuals were able to reach maturity in the Gulf as evidenced by there being no
individuals >40 mm TL. Conditions that favored larval transport in 2000 may not have occurred in 2001.
It also is possible that the scenario represented by 2000 is typical for H. ionthas on the upper coast and
2001 represents an aberration. Additional surveys of both beachfront groins and estuarine oyster reefs
would clarify the status of Hypsoblennius species on Texas jetties.
Scartella cristata may play a unique role in determining the composition of blenny assemblages
on Texas jetties. Even though S. cristata was found at each study site, there was a difference in the
abundance and dominance corresponding to the biogeographical break described above. S. cristata on the
Texas coast originated from at least two different source populations, the eastern Gulf and another source
likely the southern Gulf and/or western Caribbean. There also appears to be differential recruitment from
these sources. The lower and middle coast receives a large influx of recruits during the summer and lesser
numbers throughout the year at South Padre Island (Appendix A). Recruitment pulses in Galveston do not
seem to be as strong (Appendix A). This could be the underlying reason for lower densities seen on the
upper coast. The difference in population density of S. cristata may impact the other blenniid populations
through both direct and indirect competitive interactions. More information describing the nature of
62
interactions between constituent species of blenny assemblages on Texas jetties is needed to evaluate this
hypothesis.
Blennies and Fisheries Management
No only do blennies serve as excellent models for testing theories of ecology, biogeography, and
population genetics but they may also be useful to fisheries biologists. Pressures placed on fisheries
resources by human populations have increased dramatically during the past century, resulting in the
eventual collapse of various “inexhaustible” stocks. Resource managers around the world are scrambling
to maintain sustainable fisheries and still meet the needs of burgeoning populations that utilize them. The
tragedy of the commons as described by Hardin (1969), in which individuals or nations use a common
resource to its exhaustion for their own gain because the costs are shared by all, is a specter that has not
been eliminated at the dawn of the 21st Century. It has become more prevalent then ever as more
participants compete for dwindling fishery resources. The biggest challenge facing resource managers and
society over the next 100 years will be balancing needs of human populations and those of not only fishes,
but also the marine environment as a whole.
Artificial reefs are one of many management tools used along the Texas coast to conserve fish
stocks under pressure from the competing interests of commercial and recreational fishermen. Humans
have used artificial reefs for hundreds of years to increase their catch (Mottet 1985, Stone 1985). The
ability of some organisms to recruit to and establish populations on artificial substrates has been well
documented. Passage of the Artificial Reef Act by the Texas State Legislature in 1989 required the Texas
Parks and Wildlife Department (TPWD) to deploy, monitor, and manage artificial reefs in state waters
(Stephan et al. 1990). Although TPWD’s artificial reef plan recognizes jetties, groins, and other similar
structures as artificial reef habitat (Stephan et al. 1990), the plan’s primary reliance on decommissioned
petroleum production platforms as artificial reefs has negated the development of monitoring or
management programs for other substrates including jetties. This may change in light of recent findings
that rock jetties serve as a nursery habitat for structurally dependent, economically important fishes such
as lutjanids and sparids in the absence of other suitable substrate (Hernandez et al. 2001).
63
The last comprehensive survey in the northwest Gulf of finfish landings from jetties, groins, and
piers was conducted in 1973. It indicated that 288,000 recreational anglers from the Mississippi River
delta to Brownsville captured 15 million kg of fish in 1970 from jetties, piers, and bridges on both the Gulf
and the bays (Deuel 1973). For the small amount of area represented by jetties on the shores of the
northwest Gulf, this seems to be a disproportionately large number of anglers. It appears that jetties not
only attract and concentrate fishes but anglers as well. TPWD surveys indicate that spotted seatrout,
Cynoscion nebulosus; red drum, Sciaenops ocellatus; black drum, Pogonias cromis; southern flounder,
Paralichthys lethostigma; sheepshead, Archosargus probatocephalus; Atlantic croaker, Micropogonias
undulatus; sand seatrout, Cynoscion arenarius; and gafftopsail catfish, Bagre marinus, constitute the
majority of fishes caught off Gulf jetties and piers (McEachron 1980). Though these fishes are not taken
in sufficient numbers off jetties and piers to significantly impact their populations (McEachron 1980), no
recent studies examine the role jetties play in enhancing shore-based fisheries for these species.
The evaluation of jetties or any other artificial reef’s enhancement of fish populations is a
significant issue in its use as a fisheries management tool. Although there is little consensus whether
artificial reefs enhance fisheries or merely concentrate existing fishes, recent research suggests that
location plays a major role in how the reef impacts fish populations. Deployment of artificial reefs
adjacent to abundant, natural rocky substrate attracts fishes from natural habitats; whereas, those placed in
areas without natural structure, such as the Texas coast, probably enhances fisheries (Grossman et al.
1997, Bortone 1998, Shipp 1999). One key in addressing the aggregation-enhancement issue and
evaluating performance of artificial reefs will be to determine how closely they function ecologically in
comparison to natural counterparts. This necessitates that resource managers change their focus, as the
community structure of non-game fishes likely provides a better assessment of the functional equivalency
of artificial habitats than does that of game fishes (Topolski and Szedlmayer 2000). Blennies have
potential to be excellent indicators to measure the functional equivalency of artificial habitats, such as
jetties and petroleum production platforms, to their natural counterparts (Topolski and Szedlmayer 2000)
due to their sedentary nature, relative ease of capture, great abundance, and hardiness. In many regards,
blennies are the ideal measure for functional equivalency in these habitats because they are sensitive to
64
changes in the composition of the fouling community (Topolski and Szedlmayer 2000). The structure of
blenny assemblages also may indicate the development an artificial habitat functionally equivalent to a
natural one (Topolski and Szedlmayer 2000).
Blennies also may serve as important indicators of environmental quality due to their habit of
establishing populations in close proximity to human impacts on the marine environment. Viviparous
blennies, Zoarces viviparous, have been found to be useful indicators of petroleum contamination from oil
platforms (Celander et al. 1994) and industrial chemical effluents (Vetemaa et al. 1997) in the North Sea.
Blennies may be useful environmental indicators of jetty habitats on the Texas coast as well as oil
platforms. Over 13,000 commercial vessels and an even larger number of smaller recreational and fishing
boats annually pass through channels protected by jetties at the three sites utilized in the study (Port of
Houston Authority 2001, Port of Corpus Christi Authority 2001). More than 1,000 of these commercial
vessels were tankers carrying 75.5 million tons of petroleum and 1.94 million tons of assorted chemicals
through Aransas Pass alone (Port of Corpus Christi Authority 2001). Blennies on jetties may be useful as
models to study the chronic effects of long-term sub-lethal exposures to petroleum and other chemicals.
The data presented in this study should serve as the foundation for continued examination of the utility of
blennies to fisheries biologists and resource managers.
Conclusions
The major findings of the present study are as follows:
• Four species of blenniids and one labrisomid species reside on Texas jetties. These
species formed geographically distinct assemblages at the three study sites but
further work is needed to determine if these sites are representative of the Texas
coast.
• The blenny assemblages at each site appeared to be relatively stable in species
composition over time. Observed fluctuations in CPUE were driven primarily by
temperature and may be an artifact of sampling bias.
• Scartella cristata is the dominant blenny on Texas jetties. It is a short-lived species
that spawns throughout most of the year. Further research questions should focus
65
on why this species is so abundant on Texas jetties by addressing information voids
on growth rates of other blenny species; physiological tolerances and requirements;
and interactions between S. cristata and other constituent species.
• Texas jetties represent a convergence of at least two genetically distinct populations
of Scartella cristata. The local population of S. cristata at Galveston had close ties
with Florida indicating its origins lie in the eastern Gulf. Port Aransas and South
Padre Island do not share this affinity with Florida. These local populations were
closely related to each other suggesting a source population in the southern Gulf or
Caribbean. Future work should include samples from a wider geographical range
and incorporate investigations into cohort effects on the genetic structure of local
populations.
66
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73
APPENDIX A
74
MAY 2000n=8
JULY 2000n=18
AUGUST 2000n=31
OCTOBER 2000n=6
Fig. A-1. Monthly length-frequency distributions for Scartella cristata captured atGalveston, Texas from May 2000 to August 2001. Months in which S. cristata werenot captured are omitted from this figure. Axes are standardized across each month.Y-axis is percent of monthly catch in 25% intervals. X-axis is 10 mm size classesstarting with 0-10 mm and ending with 111-120 mm.
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
TL (mm)
% o
f ind
ivid
uals
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
1000-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-
110111-120
0
25
50
75
100 0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
JUNE 2000n=5
SEPTEMBER 2000n=9
75
NOVEMBER 2000n=7
DECEMBER 2000n=3
MARCH 2001n=6
APRIL 2001n=20
MAY 2001n=12
JUNE 2001n=25
JULY 2001n=33
AUGUST 2001n=11
Fig. A-1. CONTINUEDTL (mm)
% o
f ind
ivid
uals
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
76
MAY 2000n=32
JUNE 2000n=12
AUGUST 2000n=32
SEPTEMBER 2000n=2
OCTOBER 2000n=7
Fig. A-2. Monthly length-frequency distributions for Hypleurochilus geminatuscaptured at Galveston, Texas from May 2000 to August 2001. Months in which H.geminatus were not captured are omitted from this figure. Axes are standardizedacross each month. Y-axis is percent of monthly catch in 25% intervals. X-axis is 10mm size classes starting with 0-10 mm and ending with 111-120 mm.
TL (mm)0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-
110111-120
0
25
50
75
100
TL (mm)
% o
f ind
ivid
uals
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
1000-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-
110111-120
0
25
50
75
100 0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
JULY 2000n=34
77
NOVEMBER 2000n=3
FEBRUARY 2001n=1
MARCH 2001n=1
APRIL 2001n=5
MAY 2001n=21
JUNE 2001n=41
JULY 2001n=8
Fig. A-2. CONTINUEDTL (mm)
% o
f ind
ivid
uals
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
1000-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-
110111-120
0
25
50
75
100 0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
78
MAY 2000n=36
JULY 2000n=10
AUGUST 2000n=12
MAY 2001n=1
Fig. A-3. Monthly length-frequency distributions for Hypsoblennius ionthascaptured at Galveston, Texas from May 2000 to August 2001. Months in which H.ionthas were not captured are omitted from this figure. Axes are standardized acrosseach month. Y-axis is percent of monthly catch in 25% intervals. X-axis is 10 mmsize classes starting with 0-10 mm and ending with 111-120 mm.
TL (mm)
% o
f ind
ivid
uals
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
79
MAY 2000n=23
JUNE 2000n=30
JULY 2000n=43
AUGUST 2000n=201
SEPTEMBER 2000n=240
OCTOBER 2000n=273
Fig. A-4. Monthly length-frequency distributions for Scartella cristata captured atPort Aransas, Texas from May 2000 to August 2001. S. cristata was captured everymonth except for November 2000 when no collection effort was made. Axes arestandardized across each month. Y-axis is percent of monthly catch in 25% intervals.X-axis is 10 mm size classes starting with 0-10 mm and ending with 111-120 mm.
TL (mm)0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-
110111-120
0
25
50
75
100
TL (mm)
% o
f ind
ivid
uals
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
1000-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-
110111-120
0
25
50
75
100 0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
80
DECEMBER 2000n=188
JANUARY 2000n=2
FEBRUARY 2001n=40
MARCH 2001n=16
APRIL 2001n=14
MAY 2001n=34
Fig. A-4. CONTINUED
TL (mm)0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-
110111-120
0
25
50
75
100
% o
f ind
ivid
uals
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
1000-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-
110111-120
0
25
50
75
100 0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
81
JUNE 2001n=525
AUGUST 2001n=50
Fig. A-4. CONTINUED
JULY 2001n=188
TL (mm)
% o
f ind
ivid
uals
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
82
MAY 2000n=3
JUNE 2000n=5
JULY 2000n=13
AUGUST 2000n=3
SEPTEMBER 2000n=2
DECEMBER 2000n=1
Fig. A-5. Monthly length-frequency distributions for Hypleurochilus geminatuscaptured at Port Aransas, Texas from May 2000 to August 2001. Months in which H.geminatus were not captured are omitted from this figure except for November 2000when no collection effort was made. Axes are standardized across each month. Y-axis is percent of monthly catch in 25% intervals. X-axis is 10 mm size classesstarting with 0-10 mm and ending with 111-120 mm.
TL (mm)0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-
110111-120
0
25
50
75
100
% o
f ind
ivid
uals
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
1000-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-
110111-120
0
25
50
75
100 0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
83
FEBRUARY 2001n=7
MARCH 2001n=1
APRIL 2001n=4
MAY 2001n=10
JUNE 2001n=5
JULY 2001n=8
AUGUST 2001n=2
Fig. A-5. CONTINUEDTL (mm)
% o
f ind
ivid
uals
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 111-120
0
25
50
75
100
101-110
101-110
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 111-120
0
25
50
75
100
101-110
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 111-120
0
25
50
75
100
101-110
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 111-120
0
25
50
75
100
101-110
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 111-120
0
25
50
75
100
101-110
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 111-120
0
25
50
75
100
101-110
84
JULY 2000n=3
AUGUST 2000n=3
JUNE 2001n=1
JULY 2001n=1
Fig. A-6. Monthly length-frequency distributions for Labrisomus nuchipinniscaptured at Port Aransas, Texas from May 2000 to August 2001. Months in which L.nuchipinnis were not captured are omitted from this figure except for November 2000when no collection effort was made. Axes are standardized across each month. Y-axis is percent of monthly catch in 25% intervals. X-axis is 10 mm size classesstarting with 0-10 mm and ending with 111-120 mm.
TL (mm)
% o
f ind
ivid
uals
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 111-120
0
25
50
75
100
101-110
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 111-120
0
25
50
75
100
101-110
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 111-120
0
25
50
75
100
101-110
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 111-120
0
25
50
75
100
101-110
85
JULY 2000n=81
AUGUST 2000n=128
SEPTEMBER 2000n=71
OCTOBER 2000n=15
DECEMBER 2000n=59
JANUARY 2001n=5
Fig. A-7. Monthly length-frequency distributions for Scartella cristata captured atSouth Padre Island, Texas from July 2000 to August 2001. S. cristata was capturedevery month except for November 2000 when no collection effort was made. Axesare standardized across each month. Y-axis is percent of monthly catch in 25%intervals. X-axis is 10 mm size classes starting with 0-10 mm and ending with 111-120 mm.
TL (mm)0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-
110111-120
0
25
50
75
100
% o
f ind
ivid
uals
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
1000-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-
110111-120
0
25
50
75
100 0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 101-110
111-120
0
25
50
75
100
86
FEBRUARY 2001n=11
MARCH 2001n=50
APRIL 2001n=45
MAY 2001n=687
JUNE 2001n=282
JULY 2001n=457
AUGUST 2001n=161
Fig. A-7. CONTINUEDTL (mm)
% o
f ind
ivid
uals
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 111-120
0
25
50
75
100
101-110
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 111-120
0
25
50
75
100
101-110
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 111-120
0
25
50
75
100
101-110
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 111-120
0
25
50
75
100
101-110
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 111-120
0
25
50
75
100
101-110
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 111-120
0
25
50
75
100
101-110
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 111-120
0
25
50
75
100
101-110
87
MARCH 2001n=1
MAY 2001n=22
JUNE 2001n=1
Fig. A-8. Monthly length-frequency distributions for Hypleurochilus geminatuscaptured at South Padre Island, Texas from July 2000 to August 2001. Months inwhich H. geminatus were not captured are omitted from this figure except forNovember 2000 when no collection effort was made. Axes are standardized acrosseach month. Y-axis is percent of monthly catch in 25% intervals. X-axis is 10 mmsize classes starting with 0-10 mm and ending with 111-120 mm.
TL (mm)
% o
f ind
ivid
uals
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 111-120
0
25
50
75
100
101-110
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 111-120
0
25
50
75
100
101-110
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 111-120
0
25
50
75
100
101-110
88
JULY 2000n=19
AUGUST 2000n=15
SEPTEMBER 2000n=11
DECEMBER 2000
APRIL 2001n=3
MAY 2001n=2
Fig. A-9. Monthly length-frequency distributions for Labrisomus nuchipinniscaptured at South Padre Island, Texas from July 2000 to August 2001. Months inwhich L. nuchipinns were not captured are omitted from this figure except forNovember 2000 when no collection effort was made. Axes are standardized acrosseach month. Y-axis is percent of monthly catch in 25% intervals. X-axis is 10 mmsize classes starting with 0-10 mm and ending with 131-140 mm.
TL (mm)
0
25
50
75
100
% o
f ind
ivid
uals
0
25
50
75
0-10 21-30 41-50 61-70 81-90 101-110
0
25
50
75
100
0
25
50
75
0
25
50
75
100
0
25
50
75
100
121-130
0-10 21-30 41-50 61-70 81-90 101-110
121-130
0-10 21-30 41-50 61-70 81-90 101-110
121-130
0-10 21-30 41-50 61-70 81-90 101-110
121-130
0-10 21-30 41-50 61-70 81-90 101-110
121-130
0-10 21-30 41-50 61-70 81-90 101-110
121-130
100
100
100
n=1
89
JUNE 2001n=7
JULY 2001n=9
AUGUST 2001n=12
Fig. A-9. CONTINUEDTL (mm)
% o
f ind
ivid
uals
0
25
50
75
100
0-10 21-30 41-50 61-70 81-90 101-110
121-130
0
25
50
75
100
0-10 21-30 41-50 61-70 81-90 101-110
121-130
0
25
50
75
100
0-10 21-30 41-50 61-70 81-90 101-110
121-130
90
APPENDIX B
91
APPENDIX B. Sequences for each haplotype characterized at Florida and Texas localities. Underscores ( _ ) represent alignment gaps.
HAPLOTYPE A
CTGCC_TTTAAAAGTT_GGATGTACAT_GTATGTATTAACACCATAAATTTATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCA_CATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCATTTAATGAACTATTCCTGGCATCTGGTTC
HAPLOTYPE B CTGCC_TTTAAAAGTT_GGATGTACAT_GTATGTATTAACACCATAAATTTATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCACTTAATGAACTATTCCTGGCATCTGGTCT
HAPLOTYPE C CTGCC_TTTAAAAGTT_GGATGTACAT_GTATGTATTAACACCATAAATTTATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATAATATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCACTTAATGAACTATTCCTGGCATCTGGTCT
HAPLOTYPE D
CTGCC_TTTAAAAGTT_GGATGTACAT_GTATGTATTAACACCATAAATTTATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCATTTAATGAACTATTCCTGGCATCTGGTCT
HAPLOTYPE E CTGCC_TTTAAAAGTT_GGATGTACAT_GTATGTATTAACACCATAAATTTATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCACTTAATGAACTATTCCTGGCATCTGGTTC
92
HAPLOTYPE F CTGCC_TTTAAAAGTT_GGATGTACAT_GTATGTATTAACACCATAAATTTATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGAATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCACTTAATGAACTATTCCTGGCATCTGGTCT
HAPLOTYPE G
CTGAC_TTGAAAAGTT_GGATGTACAT_GTATGTATTAACACCATAAATTTATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCACTTAATGAACTATTCCTGGCATCTGGTTC
HAPLOTYPE H CTGCC_TTTAAAAGTT_GGATGTACAT_GTATGTATTAACACCATAAATTTATATTAACCATTAATTCATAGTATTAAATACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCATTTAATGAACTATTCCTGGCATCTGGTCT
HAPLOTYPE I
CTGCCATTTAAAAGTT_GGATGTACAT_GTATGTATTAACACCATAAATTTATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCACTTAATGAACTATTCCTGGCATCTGGTTC
HAPLOTYPE J CTGAC_TTGAAAAGTTGGGATGTACAT_GTATGTATTAACACCATAAATTTATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCA_CATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCATTTAATGAACTATTCCTGGCATCTGGTTC
93
HAPLOTYPE K CTGAC_TTGAAAAGTTGGGATGTACAT_GTATGTATTAACACCATAAATTTATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATAATATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCACTTAATGAACTATTCCTGGCATCTGGTTC
HAPLOTYPE L
CCGAC_TTGAAAAGTTGGGATGTACATAGTATGTATTAACACCATAAATTTATATTAACCATTAATTCATAGTATTAAATACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCATTTAATGAACTATTCCTGGCATCTGGTTC
HAPLOTYPE M
CTGCCATTGAAAAGTTGGGATGTACAT_GTATGTATTAACACCATAAATAGATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCA_CATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCACTTAATGAACTATTCCTGGCATCTGGTTC
HAPLOTYPE N CTGCCATTGAAAAGTTGGGATGTACAT_GTATGTATTAACACCATAAATGGATATTAACCATTATTTCATAGTATTAAGTACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATAATATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCACTTAATGAACTATTCCTGGCATCTGGTTC
HAPLOTYPE O
CTGCC_TTGAAAAGTT_GGATGTACAT_GTATGTATTAACACCATAAATTTATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCACTTAATGAACTATTCCTGGCATCTGGTTC
HAPLOTYPE P CTGCC_TTGAAAAGTTGGGATGTACAT_GTATGTATTAACACCATAAATTGATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGAATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCACTTAATGAACTATTCCTGGCATCTGGTTC
94
HAPLOTYPE Q
CCGAC_TTGAAAAGTTGGGATGTACAT_GTATGTATTAACACCATAAATTTATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCACTTAATGAACTATTCCTGGCATCTGGTTC
HAPLOTYPE R CTGCCATTGAAAAGTTGGGATGTACAT_GTATGTATTAACACCATAAATTCATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCA_CATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCATTTAATGAACTATTCCTGGCATCTGGTTC
HAPLOTYPE S CTGCC_TTGAAAAGTTGGGATGTACAT_GTATGTATTAACACCATAAATAGATATTAACCATTAATTCATAGTATTAAATACATGTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGGATACATAACCCATTTATATATTAACACCAAACTAAAAGAATT_AACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCATTTAATGAACTATTCCTGGCATCTGGTCT
HAPLOTYPE T CTGCC_TTTAAAAGTT_GGATGTACAT_GTATGTATTAACACCATAAATTTATATTAACCATTAATTCATAGTATTAAATACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCATTTAATGAACTATTCCTGGCATCTGGTTC
HAPLOTYPE U
CCGAC_TTGAAAAGTTGGGATGTACAT_GTATGTATTAACACCATAAATAGATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCACTTAATGAACTATTCCTGGCATCTGGTTC
95
HAPLOTYPE V CTGCC_TTTAAAAGTT_GGATGTACAT_GTATGTATTAACACCATAAATTTATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGGAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCACTTAATGAACTATTCCTGGCATCTGGTTC
HAPLOTYPE W
CTGCCATTGAAAAGTT_GGATGTACAT_GTATGTATTAACACCATAAATTTATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACACAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCATTTAATGAACTATTCCTGGCATCTGGTCT
HAPLOTYPE X CTGCCATTGAAAAGTT_GGATGTACAT_GTATGTATTAACACCATAAATTTATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCATTTAATGAACTATTCCTGGCATCTGGTTC
HAPLOTYPE Y CTGCC_TTTAAAAGTT_GGATGTACAT_GTATGTATTAACACCATAAATTTATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGGAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCACTTAATGAACTATTCCTGGCATCTGGTCT
HAPLOTYPE Z CTACC_TTTAAAAGTT_GGATGTACAT_GTATGTATTAACACCATAAATTTATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACACAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCATTTAATGAACTATTCCTGGCATCTGGTCT
HAPLOTYPE AA CTGCC_TTTAAAAGTT_GGATGTACAT_GTATGTATTAACACCATAAATTTATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGGAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCCAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCATTTAATGAACTATTCCTGGCATCTGGTCT
96
HAPLOTYPE AB CTGCC_TTGAAAAGTT_GGATGTACAT_GTATGTATTAACACCATAAATTTATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTTCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCATTTAATGAACTATTCCTGGCATCTGGTTC
HAPLOTYPE AC CTACC_TTGAAAAGTTGGGATGTACAT_GTATGTATTAACACCATAAATTGATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTATACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCTTAACAC_AATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTCACTTAATGAACTATTCCTGGCATCTGGTTC
HAPLOTYPE AD CTGCC_TTGAAAAGTTGGGATGTACAT_GTATGTATTAACACCATAAATTGATATTAACCATTAATTCATAGTATTAAGTACATTTAGATATATAATCAACATACCATAATATACAACTATCAAGGATTATACAACATTAAGGTGTACATAACCCATTTATATATTAACACCAAACTAAAAGAATTTAACCCAGGAAATCTTCATAACTCAATAAGAATAGGCTCCAAGGCATTTATACCATGCATTCAACATCCCACCCATCGAAAATACTATACCCAATAAGAACCGACCATCAGTTGATATCTTAATGCCAACGGTTATTGATGGTCAGGGACAATTATTGTGGGGGTTTGACTTAATGAACTATTCCTGGCATCTGGTTC
