Total= [2+16+38+44

Lit Cited= 3

[2.. be more specific… kelp forests? Comparison of what?] Spatial Variance in Site-to-Site Comparison of Central California

John Harriman

Abstract: [3,3, 3, 3, 2, 2] 16

It is well known that species compositions differson aat large spatial scales, like between cold temperate oceans and tropical coral reefs, but on aat smaller spatial scales there can be significant variability in species composition. We sought to answer the question of whether two closely geographically related sites differ in their species composition. This question is important to the field of ecology because it shows that the spatial differences are responsible for the sustainability of different species[??] and that the scale of spatial variationce may influence reflect different patterns of environmental influence. We observed conducted surveys at Hopkins Marine Life Refuge and Point Lobos kelp forests with replicate quantitative samples of a variety of kelp forest species to determine if there was any significant difference in species composition between these sites. [what about dasys???] We found that there was a difference between the sites, but that this difference relied on whatvaried among taxonomical groupswas being surveyed and what conditions those groups were surveyed in. [???] This shows that spatial differences can be masked by temporal unpredictability, and that this unpredictability has different consequences for what is being observed.

Introduction: [38… be more careful in word selection… re-read and see if you are using the right words to convey what you mean to say… see my edits] [nice job, though!]

Geographically closely related sites can often see exhibit variability in their species compositions (Jaureguizar, 2006). In this observational study, we sought to answer the question of weather two Central California kelp forests, Hopkins and Point Lobos, differ in their abundance and composition of species dependent on their different geographic location. This question is important to the field of ecology because it shows that the spatial differences are responsible for the sustainability of different species[no… responsible for the differences in community structure, not their sustainability] and that the scale of spacespatial variation in the structure of communties may influence reflect different patterns of environmental influence. For example, In a study of marine protected areas (MPA’s) in Tasmania, it was found that the structure of the kelp forest community between site differences ofd greatly inside and outside of MPAs’s had a profound effect on the structure of the community. Over-fishing of lobsters outside the MPAs created eliminated a trophic cascade that and led to the decimation of the kelp forest because of urchin grazing, while inside the MPA, lobsters controlled urchin populations to sustain the kelp forest community (Ling et. al., 2009). Another study of the spatial effects of El Niño on kelp forests compared multiple sites along the west coast and concluded that the scale at which environmental factors influence the kelp forest is an important factor in ecological studies (Edwards, 2004). These studies are important because they can shed insight on how to manage and protect marine life and give guidelines on how to conduct future studies.

We sought to answer three specific questions in this study: (1) is there a difference in species composition between Hopkins and Lobos; (2) is there a difference in species composition between days sampled; and (3) do both site and sampling day effect species composition? We also wanted to find if species composition varied among taxa within each of these questions. [????] We conducted this study to find test for spatial difference in species composition, but we are also figuring asking whetherif temporal, and a compound interaction effect between site and day, are skewing our datainfluencing observed variation in community structure of actually seeing true site-to-site differences. Our approach to determine the difference in species composition was to collect replicate quantitative observational data in a systemized systematic manner at both sites on two different days. We accomplished this data collection by counting an assortment of different species (see species list, FigTable. 1) across different taxonomical levels, fish, invertebrates, and algae, in the kelp forests at each site. These species are good representatives of their taxonomical groups and can be used to indicate trends of the taxaeach species group as a whole. We used swath counting techniques to get a density count of each species sampled so that statistical analysis of these densities could be calculated. We tried to stay at a relatively constant depth throughout the observation to keep any depth related species distribution variability out of the data (Méléder, 2010). [too much detail for Intro… save for Methods]

We are interested in locating[???] spatial differences in site-to-site comparison of species compositions. We found that there were significant differences between the sites both spatially and temporally, and that this varied among the taxa being sampled. Invertebrates and algae were strongly correlated to being different in abundance and composition at each site and not affected by the day sampled, but the site-to-site difference in fish was overwhelmed by the different dynamics of the days sampled. This enforces that more replicate days of fish surveys are needed if we want to observe any site-to-site differences. Because some species are more mobile and more influenced by their physical environment, there are differences in the strength to which a species supports this study[???] because of its limited replication. We want to understand what shapes an environment from an ecological viewpoint of species interacting with their geographical and physical environment on a spatial scale, and we realize that temporal differences may be influencing what we see.

Methods: [2,2, 4, 2, 3, 2, 2, 0, 6, 3, 3, 2, 3, 2, 3, 4, 4] = 44

Note how often I have to replace your words with the word “test”!

In order to determine the spatial differences between Hopkins and Point Lobos, we conducted an observational sampling systemstudy using quantitative swath counting procedures on SCUBA. We counted a range of species (see species list, FigTable.1) in different taxonomical groups, fish, invertebrates, and algae, in the kelp forest at these two sites on two different days. These species are good indicator species of the taxonomical group they are representing, and these taxa represent important contributors to the kelp forest ecosystem. These species are also countable, which made them prime candidates for our quantitative survey. We used quantitative observational studies because they are the ideal method for obtaining these data that allow for valid, reliable, and unbiased data to be collected that can be replicated in future experiments (Winter, 2000).

Study System

We surveyed both Hopkins and Point Lobos on October 11 and October 13, 2011. Hopkins Marine Life Refuge (36.62°N 121.90°W) is located in the Monterey Bay and is one of the most protected kelp forests on the Central California coastline. Point Lobos (36.5205°N 121.9402°W) is downcoast of Hopkins at the northern range of the Big Sur coastline. Point Lobos is much less protected than Hopkins and is very susceptible to large storms creating large swell and surge in the area. Point Lobos also has a higher degree of relief in its benthic structure than Hopkins, but both sites are dominated by very hard, granitic substrate covered in a plethora of kelp forest species (personal experience). These sites are both marine protected areas that do not allow the removal of any species from their waters. This is important because it takes out any variability between sites that may be associated with fishing or collecting that could put a human influenced bias into the data. [cite others who have described your study sites in greater detail, like Watanabe]

(1) Is there a difference in species composition between Hopkins and Lobos?

To answer test thise hypothesis that there is a difference between the species composition between Hopkins and Lobos, we conducted replicate quantitative swath sampling on SCUBA at both sites. We laid out replicate 30 meter transects at 5 meter intervals along a main transect line in buddy pairs and counted each individual of each species on the species list (Fig. ure 1) in a two meter swath along the transect. We accomplished this by having one buddy on each side of the tape counting in a 1x30 meter swath to end up with two 1x30 swaths for a combined 2x30 meter swath along the transect. Multiple passes of the transect were completed to collect data on the different taxonomical groups.

A PERMANOVA of all species was created used to show test if there was any significant difference in species composition between sites. A PERMANOVA creates a p-value that is used to decipher significant statistical differencescompares the species composition ans relative abundance of species between samples. If this p-value is below 0.05, a hypothesis that states there is a difference can be accepted, but if the p-value is above 0.05 this hypothesis must be rejected and a null hypothesis of no difference must be accepted. [you don’t need to explain this… every ecologist should know this.]

Does species composition vary by taxa between Hopkins and Lobos?

In order to confirm test the hypothesis that species composition varies among taxonomical groups between Hopkins and Lobos, we collected data in the same fashion as stated earlier, but segregated the counts into taxonomical groups. The first swim out of the tape was to collect fish data in order to not scare off or attract fish that would bias the data in a volume based swath of 2x2x30 because fish are often found in the water column and not just attached to the bottom. We swam the same transect back to the starting point to collect counts of algae and invertebrates on the 2x30 meter benthic swath.

Variance analysis was conducted to see where variance in the data was coming from between site-to-site differences and day-to-day differences to tell if site was influencing the data more than anything else. A PERMANOVA p-value was also created used to tell if there was a significant difference between sites for each taxonomical group to either accept or reject if species composition varied by taxa[??]if it was below or above 0.05 respectively.

(2) Is there a difference in species composition between days sampled?

In order to answer test if there is a difference in species composition between days, we conducted the same sampling regime as we did in our first question, but added in the replicate days to split up our data. We sampled on two different days at both sites, in which the first day was calm, while second day saw a large swell hit the coastline at both sites.

A PERMANOVA p-value was also created for this hypothesis to tell if we should reject or accept it.

Does species composition vary by taxa between days sampled?

In order to confirm the hypothesis of whether species composition varied by taxa between days, we used the same swath data collected for each taxonomical group and split it up between the different days sampled rather than the different sites sampled.

A variance analysis of these data was created to show if any of the explained variance could be explained by day-to-day differences. A PERMANOVA p-value for each taxon was also created in order to accept or reject our hypothesis.

(3) Do both site and sampling day effect species composition?

To test the hypothesis of whether a combination of site and sample day has an effect on species composition, we lumped all of the data for between site and between day together and made a PERMANOVA p-value to accept or reject our hypothesis. This tells us whether there is an interaction effect between site and day.

Is there an interaction between site and sampling day that varies by taxa?

To test the hypothesis that there is an interaction between site and sampling day that varies by taxa, we created a PERMANOVA p-value for each taxon to accept or reject our hypothesis.

Results:

(1) Is there a difference in species composition between Hopkins and Lobos?

We found that there was a significant difference in the species compositions between Hopkins and Point Lobos (PERMANOVA, p-value = 0.001). This difference is well represented by the multi-dimensional scaling graph (MDS) that shows a well-defined split between sites (Fig. 2). This graph is used to show that the groupings of the two sites are segregated from each other by distance. This distance represents the difference between points relative to other points on the plot (the further away a point is the more different it is). With this information, we can accept our hypothesis that a difference in species composition between Hopkins and Lobos exists.

Does species composition vary by taxa between Hopkins and Lobos?

We found that some taxa groups displayed statistically significant differences in species composition between Hopkins and Lobos, while one of groups had confounding results. Algae and invertebrates displayed significant site differences in their composition (PERMANOVA, p-value = 0.001 and 0.001 respectively). Fish, on the other hand, did not display a site difference in their composition (PERMANOVA, p-value = 0.319). Variance analysis shows that all of the explained variance for algae and invertebrates occurs between sites, while less site variance is explained by fish (Fig. 3). Some species of algae and invertebrates saw large differences in their compositions to the extreme that some were commonly present at one site and absent at the other. Species like Pterygophera californica and Eisenia arbora were commonly present at Lobos while mostly absent at Hopkins (Fig 4). This led to there being a strong correlation for differences in these taxa between sites. With this information, we were able to accept the hypothesis that between site differences varies by taxa.

(2) Is there a difference in species composition between days sampled?

We found that there was not a difference between days sampled for the composition of all species (PERMANOVA, p-value = 0.382). This allowed us reject out hypothesis of there being a difference in species composition between days sampled.

Does species composition vary by taxa between days sampled?

We found that fish have significant difference in days sampled (PERMANOVA, p-value = 0.043), but the difference in days was insignificant for algae and invertebrates (PERMANOVA, p-value = 0.724 and 0.505 respectively). Fish were relatively rarely seen, so their means were low and highly variable with respect to the limited amount of replicates for fish surveys, but there was enough data to see that day did have an affect on fish composition (Fig. 5). The variance analysis allows us to see that days sampled had a significant impact on the variability in fish data compared to algae and invertebrates (Fig. 3). These results allowed us to accept our hypothesis that species composition varies by taxa between days sampled.

(3) Do both site and sampling day effect species composition?

We found that the interaction of site and day sampled did not have an effect on species compositions for all species sampled (PERMANOVA, p-value = 0.375). This allowed us to reject our hypothesis that the interaction effect is prevalent on all species sampled.

Is there an interaction between site and sampling day that varies by taxa?

Even though we did not see an interaction affect on all species sampled, we did find that there was an interaction effect on fish (PERMANOVA, p-value = 0.015). This was not seen on algae and invertebrates however (PERMANOVA, p-value = 0.926 and 0.569 respectively). This allowed us to accept our hypothesis that there is an interaction effect between site and sampling day that varies by taxa.

Discussion:

The difference in species composition between Hopkins and Point Lobos is prevalent throughout this study. There are multiple variables that can explain these differences whether it is their physical location on a map, their relief patterns, or their exposure to the turbulent and unpredictable Pacific Ocean. These differences may be affecting different recruitment patterns and sustainability of different species in their environments between these sites. Just as there are spatial differences in species compositions on large geographic scales, like temperate oceans versus tropical reefs, location differences on a smaller scale, like in this study, can be seen as well. These differences can depend heavily on what is being observed. In this study, we saw that differences were heavily taxonomically dependent. For each of our hypothesis, we saw that our answers varied depending on what taxonomical group we were observing. This is most likely due to the fact that invertebrates and algae are much less mobile than fish. This is especially prevalent on the temporal scale that we conducted our study on. We surveyed on two very different days with respect to the ocean conditions. The first day saw calm conditions that allowed for fish to be roaming around the reef in plain visual site, while on the second day, there was a large swell in the water that made fish hide or swim away and not be easily counted, while the sessile algae and invertebrates just stayed where they were. This temporal bias in the data overwhelmed our goal to see if there was a true difference in fish assemblages between sites.