Matthew Bishop5/13/12

BIOE 161/L

Total score: 78/100

Title [[3/4 you have the right information in there, but it’s long and not exciting]]

Determining associations between macroinvertebrate and algal species and habitat using

the swath method in a kelp forest at Hopkins Marine Reserve in Monterey, California

Abstract [[not required, but this is a fair shot

Analysis of uniform point contact (UPC) species and habitats was used to determine if

swath species partitioned resources according to niche diversification through means of

species or habitat interaction. Three questions were developed to answer this hypothesis.

First, is there an association between swath species composition and (1) UPC species

composition and/or (2) habitat attributes?[[awkward construction here]] Second, do the

associations differ in relative strength? Third, for select species, are there a set of strong

association/disassociations and do these make sense? An observational approach utilizing

UPC and swath sampling was used to determine correlation between species and habitat.

It was found that habitat had the most contribution to species abundance and distribution

and is the cause of the niche diversification of swath species.

Clarity [[ 10/14 – Avoid hanging prepositions

Introduction [[14/20 – you’re having some problems describing the concepts of niche

diversification and resource partitioning and articulating the hypotheses. Good use of the

scientific literature and a pretty good description of the study site, but no mention of the

novelty of this study]]

Swath analysis was used to determine the degree of connection between swath

communities and the habitat (substrate and relief) found using uniform point contact

(UPC) sampling. [[don’t lead with the methods, lead with the ecological questions or

context. Also “swath analysis” is not something that everyone understands, you need to

explain it and the species further down]] Patterns of species distribution and abundance

are determined by a complex interaction of biotic and abiotic factors (Santos 1993).

Species interactions with their habitat may lead to cCompetition for resources between

similar species and may lead to resource partitioning of the common resource being

sought afterwhereby similar species adapt to different habitat or other niches to minimize

competition [[it’s not the interactions with the habitat, but the interactions between

species and the complexity of the habitat that enable niche diversification]]. Analyses of

resource partitioning have provided much of the evidence for competition as a

mechanism which results in niche separation and coexistence of ecologically similar

species (Hines 1982). Our study focuses on the linkages between biotic (mobile and

sessile invertebrates and alageswath species and UPC species) and abiotic (swath species

and UPC habitat substrate type and relief) interactions factors and whether either has

higher interaction strength. These interactions may help explain underlying causes for the

resource partitioning observed [[you’re not testing the cause, you’re just trying to observe

the patterns]]. However, swath species, macroinvertebrates, and algae appear to

demonstrate this resource partitioning by means of the niche diversification hypothesis,

which structures their community. Niche diversification may be the product of

biochemical specialization, biotic relationships and microhabitat specialization (Grassle

and Sanders 1973). Many swath organisms occupy the same niche, compelling the need

for niche diversification [[are you saying the SHOULD evolve to diversify? If niche

diversification is present in this system, there shouldn’t be many species occupying the

same niche]].

Three questions have been developed to determine the linkage between swath

species, UPC species, and the habitat [[you kind of have to describe what these species

are, not just call them “swath species” which means nothing]]. First, is there an

association between swath species composition and (1) UPC species composition and/or

(2) habitat attributes? Second, do the associations differ in relative strength? Third, for

select species, are there a set of strong positive or negative association/disassociations

and do these make sense? From By analyzing and interpreting the data found by the

swath and UPC method, we can determine the driving force for structuring communities

[[nope, we can just test for associations, not determine drivers]]. Being able to determine

what the cause for community structure is, whether it is species-species associations,

species-habitat associations, or a combination of both, allows underlying processes to be

tested. Our null hypothesis states that we would expect to see no associationdifference

between mobile invertebrates and swath species and habitat characteristicss. Our

alternative hypothesis states that we would expect as habitats become more dissimilar, the

swath species within those habitats also become more dissimilar.

The kelp forest at Hopkins is an ideal study site to answer these questions because

it is in a Marine Protected Area. The interactions observed between differing and

conspecific species, and species with their habitat, are not manipulated by human

processes, but by natural disturbances. The forest is located on a shallow, granitic reef,

which allows for varying reliefs and patchiness of other substrates to be observed

interacting with a variety of species [[good, this is the right kind of information and the

right level of detail]]. Associations between species and habitat can be made with relative

certainty because an area that is only manipulated by biological or abiotic processes is

present. This is important to our understanding of ecological processes because we can

better understand how species may coexist and why species may diverge from one

another. Understanding this coexistence can help better conserve the diversity of kelp

forests and limit the losses from kelp forests that could occur in the future. Changes in

[species] abundance can have major ecosystem level consequences (Byrnes et. al. 2006).

Certain species cause a particular niche to persist within a community, adding to the need

for protection for the community.

Methods [[15/18 – overall quite good, but you could better link methods to hypotheses

and better describe data analysis, including how you interpret results]]

General Approach

We conducted an observational field study using the swath method to determine

the abundance of macroinvertebrate and algal species along a transect. [[this next

sentence should describe the swath method generally]] Using the swath method to count

the number of macroinvertebrate and algal species, we were able to obtain swath species

associations with species and habitat previously sampled using the UPC method. An

ANOVA test was subsequently used and correlations between swath species abundance,

UPC species abundance, and UPC habitat were determined. [[you’ve got the right general

idea here]]

System Description

This study was conducted at Hopkins Marine Reserve in Monterey, California,

latitude: 36° 37.20' N., longitude: 121° 54.18' W. This is site is a Marine Protected

Area, having no take within it, making it an ideal site to study invertebrate and algal

abundance and their interactions. Since Hopkins is a protected area, the organisms are

only manipulated by natural disturbances, leaving them unaltered by people and able to

naturally interact with other organisms and their habitat. Kelp forests are a biogenic

habitat that supports a diverse collection of organisms within it. Some organisms, which

require the same resource, are able to naturally interact. This allows for true interactions

to be observed and inferences from these observations to be made. [[good]]

Study Design

Is There an Association Between Swath Species and UPC Species and/or Habitat

Attributes?

[[start by talking about how your collection methods were designed to enable you

to answer this question, and then the analysis]] Using ANOVA, the data was analyzed

[[passive voice]] and the significance of UPC habitat and UPC species abundance on

swath species was determined. The swath method allows for a count of several species

along a transect, giving the relative abundance of each species at varying points and

shows the species composition for an area. By obtaining an abundance of each species it

is possible to make comparisons with results obtained using the UPC method. This shows

associations between species as well as their interactions with the surrounding habitat

(substrate and relief).

Do These Associations Differ in Relative Strength?

[[same as above]] Using ANOVA, the relative strength of contribution from

habitat attributes and UPC species on the variance in swath species abundance was

determined. Observing species abundance can yield interaction strengths between species

and their habitat. If more species than others are encountered, and their associations with

different substrates or reliefs are known, inferences about species-species interactions

relative to known interaction strengths from the UPC method can be made. If many

species are found on a certain substrate and another species is known to have a high

association with that same substrate, interaction strengths can be determined.

Are There Strong Associations/Disassociations for Select Species and do These Make

Sense?

Two species, Cryptochiton stelleri and Lithopoma gibberosa, were chosen to

determine if any strong associations or disassociations were present. These species were

chosen because they are both grazing molluscs, which are believed to compete for the

same resources due to both being benthic algae foragers. Observing the species and

habitat associations from the UPC method, coupling it with the abundance of species

obtained from the swath method, inferences can be made about

association/disassociations between specific species. Some species may show a similar

habitat association, but may be disassociated with each other because of it.

Data Collection

Using SCUBA, dive pairs used the swath method to determine the abundance of

macroivertebrate and algal (Macrocystis pyrifera and Cystoseria osmundacea) species

along a transect. Eleven dive pairs set up 30 meter transects using meter tapes on an

offshore cable, between the meter marks 85 and 135 on April 17, 2012. Each diver was

responsible for 6, 5 x 1 meter subsections on either the right or left side of the meter tape.

The divers were tasked with counting the number of macroinvertebrate species, M.

pyrifera, and C. osmundacea that were encountered within those subsections. On each

meter mark 2 transects were reeled out, one offshore at a heading of 90° and one onshore

at a heading of 270°. Only organisms within 1 meter perpendicular toof the meter tape

were counted.

The swath species data was collected, along with the UPC species and UPC

habitat data retrieved on April 10, 2012. The UPC sampling was done on a 30 meter

transect and divers were tasked to sample relief, substrate, whether or not there was drift

algae, and the organism associated with the point. Two transects, one onshore at a

heading of 90° and one offshore at a heading of 270°, were conducted. Sampling was

done every half meter along the transects. Using an ANOVA, analysis of variance, test,

the correlations between swath species and UPC species, as well as swath species and

UPC habitat, were determined. A Bray-Curtis dissimilarity matrix, species dissimilarity,

and a Euclidean distance matrix, habitat dissimilarity, were used in the ANOVA test.

Eight swath species were compared with substrate, relief, and UPC species and their

correlations for each were graphed. The correlations ranged from -0.3 to 0.3, with strong

positive or negative correlations being greater than 0.1 or less than -0.1. Correlations that

fell between -0.1 and 0.1 were considered weak. Strong, positive and negative

associations and strong, positive and negative disassociations were interpreted from these

graphs.

[[other details you want to include in this are the total number of UPC data points, and

the spatial scale at which you can compare UPC and \swath species (i.e. 10 square

meters, because your swath data was in 5m x 2m blocks).

Results [[13/16 – this is good! Too much detail in the general results. Good job

presenting results in terms of your questions, but I didn’t feel you really answered the

first question. Nice job with the figure formatting and captions]]

General Results

Overall, the swath species generally had similar strong associations for habitats

(substrate and relief) that would be expected for the different species. C. osmundacea and

M. pyrifera had strong, positive correlation for bedrock and shallow relief, and a strong,

negative correlation with sand (Fig. 1). Balanus nubilus shows a strong, positive

correlation with boulders and high relief, while Styela montereyensis has a strong,

positive correlation with bedrock and shallow relief. Each has a strong, negative

correlation with sand (Fig. 1). Patiria miniata and Pisaster giganteus showed relatively

no strong correlations between with any substrate or relief. C. stelleri has a strong,

positive correlation with boulder, bedrock, and moderate relief with a strong, negative

association with sand. L. gibberosa shows a strong, positive correlation with high relief,

and strong, negative correlations with sand, boulders, and moderate relief (Fig. 1).

Each of the similar species showed some similarities in the organisms that they

were either positively or negatively correlated with. C. osmundacea and M. pyrifera both

showed a strong, positive correlation with other C. osmundacea, colonial tunicates, and

Dictyoneurum californicum. M. pyrifera showed an extremely strong, positive correlation

with solitary tunicates. Each had a strong, negative correlation with dead M. pyrifera

holdfasts. B. nubilus and S. montereyensis showed a strong, positive correlation with

branching red algae and a strong, negative correlation with shell debris. P. miniata and P.

giganteus showed a strong, positive correlation with barnacles, and strong, negative

correlations with colonial tunicates and Corynactis californica. C. stelleri and L.

gibberosa showed a strong, positive correlation with branching and bushy red algae, and

D. californicum (Fig. 2). [[this is much more detail for the general results than I’d

envisioned]]

Is There an Association Between Swath Species and UPC Species and/or Habitat

Attributes?

Using a standard p-value of 0.05, variance between swath species and UPC

habitat had a p-value of less than 1x10-6 (Table 1). Analysis of the data between swath

species and UPC species concluded that variance between swath and UPC species was

less than 1.1x10-5 (Table1). From the p-value of both, we can determine both UPC

species and habitat variance from swath species are statistically significant. [[not quite

sure what the answer to this question is from what you wrote]]

Do These Associations Differ in Relative Strength?

Regarding variance in the abundance of swath species, habitat attributes account

for more variance than does UPC species along the transects. Habitat attributes account

of 76% of the variance, while UPC species only account for 24% of the variance (Table

2). This shows that habitat and UPC species contribute to the variance in swath species

along a transect at an approximate 3:1 ratio.

Are There Strong Associations/Disassociations for Select Species and do These Make

Sense?

C. stelleri and L. gibberosa were chosen due to each being a mollusc and each

being algae grazers. This would likely indicate that they would be competing for similar

resources and nutrients. C. stelleri and L. gibberosa each showed a strong, negative

correlation with sand. However, C. stelleri showed a strong, positive correlation with

boulders, while L. gibberosa displayed a strong, negative correlation for boulders (Fig.

1). In terms of relief, C. stelleri has a strong, positive correlation with moderate relief and

L. gibberosa shows a strong, negative correlation with moderate relief (Fig. 1). Each

showed a strong, positive correlation with branching and bushy red algae, and D.

californicum (Fig. 2). C. stelleri showed a strong, positive correlation with Diopatra

ornata while, L. gibberosa showed a strong, negatively correlation with D. ornata. L.

gibberosa has a strong, positive correlation, and C. stelleri has a strong negative

correlation, with Phragmatopoma californica (Fig. 2).

Table 1: Analysis of Variance Table. Shows the variance

between swath species, UPC species and UPC habitats. P-values

are given, showing significance of habitat and UPC species.

Coefficients are for the line of best fit and standard error is the

deviation from the sampling statistics. The t-test is used to

determine if the means of groups are statistically different from

each other.

Source Percent of variance

explained in Swath

Species abundances

Habitat attributes 76%

Table 2: Variance in Swath Species Abundance Caused by

Habitat Attributes and UPC Species Abundance. Habitat

attributes account for 76% of the explained variance in swath

species abundance while UPC species abundance accounts for

24%.

UPC Species

abundances

24%

Substrate or Releif

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

CO

RR

ELA

TIO

N

CYSTOSEIRA

Substrate or Releif

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

CO

RR

ELA

TIO

N

MACROCYSTIS_PYR-

Substrate or Releif

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

CO

RR

ELA

TIO

N

BALANUS_NUBILUS

Substrate or Releif

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

CO

RR

ELA

TIO

N

STYELA_MONTEREY-

Substrate or Releif

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

CO

RR

ELA

TIO

N

CRYPTOCHITON_ST-

Substrate or Releif

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

CO

RR

ELA

TIO

N

LITHOPOMA_GIBBE-

Substrate or Releif

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

CO

RR

ELA

TIO

N

PATIRIA_MINIATA

Substrate or Releif

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

CO

RR

ELA

TIO

N

PISASTER_GIGANT-

Figure 1: Swath Species Correlations With UPC

Substrate and Relief. This figure shows

associations between swath species, and UPC

substrates and reliefs. Correlation is deemed strong

when it is greater than 0.1 and less than -0.1.

Correlations are week when they fall between -0.1

and 0.1.

SPECIES_2$

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

Correlation

CRYPTOCHITON_STELLERI

UPC Species

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

Correlation

LITHOPOMA_GIBBEROSA

Figure 2: Swath Species Correlations With

UPC Species. This figure shows the

associations between swath species and

UPC species for C. stelleri and L.

gibberosa.. Correlation is deemed strong

when it is greater than 0.1 and less than -

0.1. Correlations are week when they fall

between -0.1 and 0.1.

[[nice figure captions and good formatting on your figures]]

Discussion [[17/22 – you should work on using the sci literature to compare your results

to those from previous studies and put it all in context. Also you could benefit from a

general introductory paragraph that summarizes the results across the board before you

dive into the hypothesis-specific results. Here, keep the details about the results to a

minimum, and focus on the explanation for the results and potential mechanisms as much

as possible. When you identify problems with the sampling method, you should also

indicate how they could be fixed.]]

Is There an Association Between Swath Species and UPC Species and/or Habitat

Attributes?

Both UPC habitat and UPC species had a p-value significantly less than the

standard p-value of 0.05. Habitat, p-value of 1x10-6, was slightly more significant than

UPC species, p-value of 1.1x10-5. Even though habitat, according to the variance analysis,

is more significant than species, this is a minuscule amount, which implies that there is a

significant association between swath species and UPC species and habitat. However,

being that the difference is minuscule, habitat contributes a slightly greater influence in

the structuring of communities. In kelp forests, wave motion is generally constant, which

brings a constant influx of nutrients into the forest. With a constant stream of nutrient, the

trophic levels are no longer vying for a limiting nutrient source. Instead, species are vying

for space, which becomes the limited resource. Habitat, having a slightly more significant

p-value, has a slightly stronger influence in determining the distribution and abundance

of swath species in a kelp forest.

Do These Associations Differ in Relative Strength?

Habitat attributes accounted for approximately three quarters of the variance in

swath species abundance along the transects. UPC species abundance, however,

accounted for approximately one quarter of variance in swath species abundance. Habitat

attributes contributed heavily to swath species variance, meaning that species-habitat

interactions had a stronger effect on where species would and wouldn’t be found as

opposed to species-species interactions. From this, it can be inferred that habitat,

substrate and relief, are the limiting resource of the kelp forest. The major limiting

resource for sessile species is usually primary space on the rock substratum or, for algae,

space in the light (Menge and Sutherland 1976). By accounting for 76% of the variance

found in swath species abundance, habitat and swath species are found to be highly

connected. This connection states that habitat becomes the resource that is sought after by

species that exploit the same niche.

Are There Strong Associations/Disassociations for Select Species and do These Make

Sense?

Between C. stelleri and L. gibberosa, each have a strong, negative correlation

with a sandy substrate. This implies that neither is likely to be found where there is sand.

There was a strong disassociation between C. stelleri and L. gibberosa and a boulder

substrate. C. stelleri displayed a strong, positive correlation with boulders and L.

gibberosa showed a strong, negative correlation with boulders. This means that C. stelleri

is likely to be found on a boulder substrate, while L. gibberosa generally won’t be. These

two species also displayed a strong disassociation for moderate relief. C. stelleri has a

strong, positive correlation with moderate relief, meaning that it is generally found in

area with moderate relief. L. gibberosa has a strong, negative correlation with moderate

relief, meaning it generally isn’t found in those areas. However, L. gibberosa has a

strong, positive correlation with high relief, generally being found in areas with high

relief. Each was strongly associated with branching and bushy red algae. This can be

attributed to C. stelleri and L. gibberosa being grazers, with algae generally growing on

bedrock or boulders. [[make sure you’re not just repeating your results]]

C. stelleri and L. gibberosa are grazers that actively search for algae to consume,

which grows on rocky substrates. The data shows that these two similar species are not

associated with the same substrates and reliefs. These Each species appears to avoid the

reliefs and substrates that each arethe other is associated with. C. stelleri is mostly found

on boulders with moderate relief. L. gibberosa would possibly be found on bedrock, due

to algae growing on the rocky substrate, in areas with high relief. Taking into account the

fact that each is found where the other generally avoids, these two species are an ideal

example of niche diversification. These two molluscan species, both grazers that

consume similar nutrients, have partitioned the habitat where their sources of nutrients

are found. This relieves the competition for mutual resources being sought after. These

species also confirm our alternative hypothesis, which states that with increasing habitat

dissimilarity there will be increased species dissimilarity. C. stelleri was found on

dissimilar substrate than L. gibberosa, also being found on dissimilar relief.

However, problems that could have occurred with this study include sampling

errors, species identification errors, transect headings were not followed, and species

were missed or were included that shouldn’t have been. Divers could have sampled the

wrong points, obtaining the wrong relief, substrate or organism for the transect during

UPC sampling. Species may have been identified incorrectlywrong or passed over

because their identity was unknown. This would give less abundance of a species and the

composition of a site would be skewed during swath sampling. The initial headings for

the transects could have not been followed, yielding different substrates and reliefs that

would alter the habitat composition of the data [you mean mismatch between swath and

UPC data? How would you fix this problem?]. Divers could have included species that

were out of their sampling zone, or missed large numbers of species, which would alter

abundances.

C. stelleri and L. gibberosa are a good example of species that compete for a

mutual resource, algae, and partition the limiting resource, habitat, which facilitates the

development of the mutual resource. This is done to relieve competition, which follows

the hypothesis of niche diversification. A reduction in spatial overlap may be an

important factor in niche diversification (Alevizon 1975). C. stelleri and L. gibberosa

partitioned the habitat, reducing their spatial overlap, and causing this niche

diversification. Habitat is the major contributor in the abundance of species found in kelp

forests, whether it be algae, sessile or mobile invertebrate. Habitat is needed and utilized

by each, which makes habitat the most important component in a kelp forest. Interactions

with other similar, species are inevitable, but by partitioning the habitat, interspecific

pressures that accompany the interactions with other species can be avoided. Knowing

that habitat is highly connected to invertebrate and algal species, it is important to

conserve this limited resource. If habitat isn’t conserved, diversity of the kelp forests will

decline and eventually the kelp forests may no longer exist. It is important to manage and

maintain this important limited resource to maintain the diversity of a kelp forest and

make sure the forest persists.

Literature Cited [[6/6]]

Alevizon, W. S. 1975. Spatial overlap and competition in congeneric surfperches

(Embiotocidae) off Santa Barbara, California.

Byrnes, J., J. J. Stachowicz, K. M. Hultgren, A. R. Hughes, S. V. Olyarnik and C. S.

Thurber 2006. Predator diversity strengthens trophic cascades in kelp forests by

modifying herbivore behaviour. Ecology Letters 9: 61-71.

Grassle, J. F. and H. L. Sanders 1973. Life histories and the role of disturbance. Deep Sea

Research and Oceanographic Abstracts 7: 643-659.

Hine, A. H. 1982. Coexistence in a kelp forest: size, population dynamics, and resource

partitioning in a guild of spider crabs. Ecological Monographs 52: 179-198.

Menge, B. A. and J. P. Sutherland 1976. Species diversity gradients: synthesis of the

roles of predation, competition, and temporal heterogeneity. The American Naturalist

110: 351-369.

Santos, R. 1993. A multivariate study of biotic and abiotic relationships in a subtidal

algal stand. Marine Ecology Progress Series 94: 181-190.