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Seasonal Diversity and Abundance of Larval and
Juvenile Fishes in The Upper Barataria Estuary
Sean Jackson
Introduction Barataria Estuary
• 1.7 million hectares• Diverse Habitats
– Freshwater swamps– Salt marshes
IntroductionStudy location
IntroductionUpper Barataria Estuary
• Land Use– 41.5% forested
wetlands – 38.0% agricultural
lands– 5.2% urban land
Study Area• Upper Barataria Estuary
– Large river floodplain• Leveed from Mississippi river
• No annual flood pulse
– Precipitation only water source• Wind can influence water level
• Major Water Bodies– Bayou’s Chevreuil and Citamon – St. James Canal– Lac des Allemands
IntroductionHabitat Description
• Canal Habitats– Dredged straight channel – High banks
• Bayou Habitats– Meandering curves– Low banks
Large River Floodplain Ecology
• Floodplain Ecology– Hydrology driving force
• Flood Pulse– Habitat access– Flush nutrients into system– Homogenize water quality
IntroductionLarge River Floodplain Ecology
• Flood Pulse Concept – Predictable annual flood pulse – Spawning and nursery habitat – Timing and duration important – Atchafalaya River Basin
• Low Flow Recruitment Hypothesis– No predictable annual flood pulse– Opportunistic use of floodplain– Brazos River floodplain
IntroductionLarge River Floodplain Ecology
• Water Types– Brown
• Well mixed, high DO
– Green• Stratified, high/low DO
– Black• Low turbidity, low DO
– Tea colored• High turbidity, Low DO
IntroductionFish Reproduction
• Successful Fish Reproduction– Cues
• Photoperiod (day length)• Temperature
– Environmental requirements• Access to spawning habitat• Acceptable water quality
IntroductionFish Reproduction
• Quality Nursery Habitat– Food availability– Water quality
• Dissolved oxygen– Normoxic = >2.0 mg/L– Hypoxic = < 2.0 mg/L
• Specific conductance
IntroductionFish Reproduction
PeriodicDorosoma spp.
OpportunisticGambusia spp.
EquilibriumLepomis spp.
Small BodiedRapid Maturation
Low FecundityShort Brood Period
Long Spawning Season
Large Egg SizeHigh Parental Care
Long Spawning SeasonIntermediate Fecundity
Citation?
IntroductionEcosystem Health
• V-O-R model– Vigor – production– Organization – structure or diversity– Resilience – maintain or rebuild
• Environmental Indicators – Water quality– Fisheries catch– Habitat diversity / availability
Purpose
• Describe distribution and abundance of larval and juvenile fishes in the upper Barataria Estuary
Predictions
• Natural bayou habitats will support higher levels of fish reproduction than dredged canal habitats
Specific objectives • Determine spawning period for each
taxonomic group of fish collected in the upper Barataria Estuary
• Compare relative abundance between canal and bayou habitats for all species and for each taxonomic group during their spawning period.
• Compare water quality data between canal and bayou habitats.
• Determine the relationship between larval fish abundance and water quality
IntroductionSite Locations
12
34567
Methods
• Weekly Collections– 9 February 2007 – 25 September 2007– 4 Bayou sites and 3 Canal sites– Three traps per site
Methods
• Light traps– Powered by
chemical light stick
– 500µm nitex mesh screen
– Sample edge of waterways
– Samples kept on ice
Methods
• Light traps – Set two hours before sunset– Pick up 2.5 hours after official sunset
• Water Quality– Temperature, DO, Conductivity, and Water
Color
• Vegetation
1
2
3
x1
x2
x3
Canal (XC)
6
5
4
7
Bayou (XB)
x4
x5
x6
x7
Experimental Design
N= 3 N= 4
Methods
• Samples processed within 24 hours• Fish placed in 70% alcohol solution • Fish identified, counted, and photographed• CPUE = number per hour
MethodsData Analysis
• All analysis performed at genus level– Log transformed if needed
• Analysis of variance (ANOVA)– CPUE, temperature, dissolved oxygen, and specific
conductance between habitats
• Regression Analysis– Determine relationship b/t CPUE and environmental
variables
• Principal Components Analysis (PCA)– Water quality variables and habitat types– Habitat types and CPUE for each fish genera and
developmental stage
ResultsFish
• 4,110 larval and juvenile fish collected• 11 Families, 15 genera represented
ResultsFish
ResultsWater Quality
• Water Temperature– No difference between habitats
• Specific Conductance– Higher in canal habitat than bayou habitat (P =
<0.0001, α = 0.05)
• Dissolved Oxygen– Higher in canal habitat than bayou habitat (P =
<0.0001, α = 0.05)
ResultsWater Quality
• Hypoxic Waters• Canal - solid
– 15% of trips
• Bayou - dashed– 62% of trips– 54 day period
ResultsWater Quality
• Water Color• Sediment laden
= black• Mixed = gray• Tea = open• No green or
black water
ResultsWater Quality
Floodplain inundation
ResultsWater Quality PCA
• PC1 (x-axis) and PC2 (y-axis) account for 86.4% of variation
Variable PC1 PC2
Temperature (°C) -0.199 0.971
Dissolved Oxygen (mg/L) 0.684 0.234
Specific Conductance (µS) 0.702 0.048
Results Vegetation
• Submerged Aquatic Vegetation– Coontail - Ceratophyllum demersum – Hydrilla - Hydrilla verticillata *– Fanwort - Cabomba caroliniana
• Floating Aquatic Vegetation– Salvinia - Salvinia minima *– Water hyacinth - Eichhoria crassipes *– Water lettuce - Pistia stratiotes *
ResultsVegetation
• No vegetation at canal sites 1 and 2
ResultsLarval Fish
• 2,164 Larval fish collected
ResultsLarval Fish
Species Collection Period N Temperature DO Specific Conductance
Dorosoma spp. 3/17/07 – 7/21/07 76* 25.7 ± 0.3 2.8 ± 0.19* 249 ± 7.7*
Ictiobus spp. 3/7/07 – 3/29/07 972* 20.8 ± 0.7 2.5 ± 0.36* 221 ± 6.5*
Lepomis spp. 3/29/07 – 9/5/07 1,050* 27.6 ± 0.2 2.9 ± 0.18* 223 ± 7.0*
Pomoxis spp. 3/17/07 – 3/29/07 64 22.2 ± 0.6 1.9 ± 0.22* 228 ± 7.8*
• Rare Larvae– Cyprinus carpio N=2
ResultsLarval Fish
ResultsLarval Fish
Normoxic (black) VS Hypoxic (open) Collections
Results Larval Dorosoma spp.
• Greatest CPUE - 17 March 2007 • Canal VS Bayou
– CPUE was greater in canal habitat
Percentage of spent and not-spent females collected in Bayou Chevreuil
0
20
40
60
80
100
11/14/2005 2/4/2006 4/27/2006 7/18/2006 10/8/2006
%
Non-spent Spent
3/28/06
7/31/06
Larval Dorosoma spp.
• CPUE / Water Quality– Weakly negatively correlated to
temperature (P=0.0011, R2=0.093) – No correlation with specific conductance– No correlation with dissolved oxygen
Results Larval Ictiobus spp.
• Greatest CPUE - 17 March 2007 • Canal VS Bayou
– CPUE was greater in canal habitat
• CPUE / Water Quality– No correlations
ResultsLarval Ictiobus spp.
Results Larval Lepomis spp.
• Greatest CPUE - 31 May 2007 • Canal VS Bayou
– CPUE was greater in canal habitat
• CPUE / Water Quality– No correlation with temperature– Weakly positively correlated with specific
conductance (P=0.0005, R2=0.0813)– Weakly positively correlated with dissolved
oxygen (P=<0.0001, R2=0.1264)
ResultsLarval Lepomis spp.
ResultsLarval Lepomis spp.
ResultsLarval Lepomis spp.
Results Larval Pomoxis spp.
• Greatest CPUE - 17 March 2007 • Canal VS Bayou
– CPUE not different– No larvae collected at sites 1 and 3
• CPUE / Water Quality– No correlation with temperature– Weakly negatively correlated with specific
conductance (P=0.013, R2=0.282)– No correlation with dissolved oxygen
ResultsLarval Pomoxis spp.
0
1.1
2.2
3.3
March 17 March 23 March 29
Mea
n (±
SD
) Ca
tch
Per
Un
it E
ffo
rt
ResultsJuvenile Fish
• 1,936 Juvenile fish collected
ResultsJuvenile Fish
Species Collection Date N Temperature DO
Specific Conductance
Gambusia affinis 3/29/07 – 9/25/07 1,689 27.6 ± 0.22 2.8 ± 0.17* 218.2 ± 6.9*Heterandria formosa
4/12/07 – 9/5/07 84* 27.7 ± 0.24 2.9 ± 0.19* 221.0 ± 7.3*
Lepomis spp. 5/13/07 – 9/25/07 84 28.5 ± 0.20 2.7 ± 0.20* 194.2 ± 7.4*
ResultsJuvenile Fish
Species Collection date N Collection Sites
Lepisosteus oculatus 5/19/2007 – 6/20/2007 8 4, 5, 6, 7
Anchoa mitchilli 5/31/2007 – 6/20/2007 6 1, 2, 3
Notemigonus crysoleucas 8/16/2007 1 7
Ictalurus punctatus 5/13/2007 – 6/15/2007 5 1, 2, 6
Poecilia latipinna 6/7/2007 – 9/5/2007 27 1, 3, 4, 5, 6, 7
Menidia beryllina 5/31/2007 – 6/7/2007 6 2
Syngnathus scovelli 6/7/2007 1 3
Pomoxis spp. 4/12/2007 – 5/19/2007 3 1, 3, 7
Elassoma zonatum 4/18/2007 – 7/12/2007 13 1, 3, 5, 6, 7
ResultsJuvenile Fish
ResultsJuvenile Fish
Normoxic (black) VS Hypoxic (open) Collections
Results Juvenile Gambusia affinis
• Greatest CPUE - 21 July 2007 • Canal VS Bayou
– CPUE not different
• CPUE / Water Quality– Weakly positively correlated with temperature
(P = 0.0012, R² = 0.067)– Weakly negatively correlated with specific
conductance (P = 0.0086, R² = 0.045)– No correlation with dissolved oxygen
ResultsJuvenile Gambusia affinis
Results Juvenile Heterandria formosa
• Greatest CPUE - 2 May 2007• Canal VS Bayou
– CPUE greater in bayou habitat
• CPUE / Water Quality – No correlations
• CPUE / Lunar Illumination– Greater at illuminations of ≥75%– Weakly positively correlated with lunar
illumination (P = 0.0049, R² = 0.362)
Results Juvenile Heterandria formosa
Results Juvenile Lepomis spp.
• Greatest CPUE - 13 May 2007 • Canal VS Bayou
– CPUE not different
• CPUE / Water Quality – Weakly negatively correlated to temperature
(P=0.0019, R2=0.08) – No correlation with specific conductance– No correlation with dissolved oxygen
Results Juvenile Lepomis spp.
ResultsLarval and Juvenile PCA
• PC I (x-axis) and PC II (y-axis) account for 42.1% of the variation
Species PC1 PC2
Dorosoma spp. -0.517 -0.406
Ictiobus spp. -0.643 -0.074
Gambusia affinis 0.291 -0.087
Heterandria formosa 0.267 -0.017
Lepomis spp. larvae 0.084 -0.693
Lepomis spp. juveniles 0.195 -0.558
Pomoxis spp. -0.343 0.176
Periodic
Equilibrium
Opportunistic
Results
Results
Conclusions Spawning / Collection Period
• Similar to expected• Tidal Influence
– Menidia beryllina – Anchoa mitchilli
Conclusions Absent Species
• Absent Species– Amia calva – Bowfin or Choupic– Ameiurus spp. – Bullhead– Aphredoderus sayanus – Pirate Perch– Fundulus chrysotus – Golden Topminnow– Morone spp. – Yellow Bass– Micropterus salmoides – Largemouth Bass
• Possible causes– No reproduction– Not present in littoral zone– Not vulnerable to sampling gear – Size (opening = 3.2 ± 0.5mm)
Conclusions Upper Barataria Estuary Hydrology
• No Predictable Flood Pulse– Lack of reproductive cue– Limit access to floodplain habitat
• Lack of Flushing– Chronic hypoxia
• Barrier to Fish Movement– Small diversions– Gulf Intracoastal Waterway
Conclusions Upper Barataria Estuary Hydrology
Conclusions Upper Barataria Estuary Fish Reproduction
• Periodic strategists– Prefer canal habitat– No difference b/t hypoxic / normoxic waters– May prefer lotic habitat
• Equilibrium strategists– Prefer canal habitat– Prefer normoxic waters– Extended reproductive period
• Spawn during optimal environmental conditions
• Opportunistic strategists – Common in both habitats– Adapted to hypoxic waters– Exploit shallow edge habitat– High reproduction rate
Conclusions Upper Barataria Estuary Fish Reproduction
• Effects of Altered Hydrology– Non-opportunistic species prefer dredged canal habitats– Lepomis spp. / Bayou Habitat
• Abundant spawning habitat • Little larval production
– May conform to Low Flow Recruitment Hypothesis– May affect all components of V-O-R model
Conclusions Upper Barataria Estuary Ecosystem Health
• Vigor – Reduction of fisheries production
• Loss of habitat• Chronic hypoxia
• Organization– Shift in species composition– Reduction of diversity
• Resilience – Loss of river connectivity – Slow repopulation after environmental stress
Recommendations
• Restore Mississippi River Connection– River water flushing
NOT
Research Suggestions
• Fixed continuous water quality data recorders
• Fish reproduction and recruitment– Quarterly electrofishing surveys at fixed
sites in different habitats– Multiple year light trap and push net
monitoring of larval and juvenile fish
Questions?
Larval FishPreflexion larvae
Postflexion larvae
Early juvenile
Fully formed fins
Larval Fish Identification
Postanal myomeres Preanal myomeres
18 10
Melanophores Swim bladder pigmentation
Genus: Lepomis