Meyer, Alexandra
Overall score: 88/100
Title [[3/4 – I’m thinking something about species-habitat associations might be appropriate in this title]]
Zonation, abundance, and accumulation of fish species associated with the kelp forest at Hopkins Marine Station, Monterey, California
Clarity [[13/14 – you have a nice writing style (when you aren’t sick in bed with a fever), but you need to make sure you always read things over slowly before turning them in because there are a few phrases in here that don’t make sense]]
Introduction [[18/20]]
The interaction between a species and its habitat characteristics is a key feature of many ecological questions and studies. Coupled with the concepts of niche and resource partitioning, these interactions become a major driving force of how the ecosystem functions as a whole [[citations? You should include more context before you launch into the kelp forest specifically]]. . In efforts to reduce competitive interactions, species often segregate based on habitat traits. For example, the black and yellow rockfish (Sebastes chrysomelas) and the gopher rockfish (Sebastes carnatus) are two sister species who segregate based on depth with the former preferring shallower reefs and forcing the latter into deeper water (Larson 1980). Other habitat attributes, such as the presence or absence of macroalgae, play a role in determining the relative abundance and association of particular species with an area of the rocky reef (Bodkin 1986). Many studies concerning fish species and their habitat associations have been conducted over the years and have provided insight into the life history traits of specific species. However, most of these studies focus on specific species of fish, or a group of related fish, rather than a whole community. In our study we hope to change this by looking at community-wide associations between fish species and depth, and in conjunction, habitat features associated with those zones. To our knowledge, this study is also the first study conducted at our site of study during the spring upwelling months [[good treatment of the novelty of this study]].
Kelp forests are among the most diverse and productive communities in the world. Diverse in both species and habitat found on or around the reef, these communities are ideal places to study species –habitat associations. Environmental habitat within the kelp forest often ranges from rocky reef to sand or mudflats, with areas of great variability in relief size [[this last phrase doesn’t make much sense]]. Thus, in the kelp forest we can observe both: 1) species diversity and 2) differences in substrate and relief type. These conditions make the kelp forest so ideal to study how species associate with the habitats they are exposed to. Utilizing data collected in previous surveys of the same month, we are able to characterize the general environmental habitat structure and macroalgal population in the zones of interest (Kelp Forest Ecology, Spring 2012. “Swath Survey.”, “UPC Survey.”).
The principle objective of our study is to identify and understand community structure through the exploration of species –habitat associations, specifically in context of depth zones. To perform our research we ask two questions: 1) is there a difference in the relative abundance of fish species as function of zone? and 2) is there a difference in species accumulation as a function of zone? Our working hypothesis for this study is that there is a correlation between zone and fish species abundance and accumulation. HA: Species abundance will be greater within the shallow zone. HB: Species accumulation will be greater within the deep zone. [[you should justify why these specific hypotheses using the patterns you observed in the UPC and swath surveys, otherwise it’s quite strange. Many people used a couple of figures to show differences in habitat features across the two depth zones]]
Methods [[15/18]]
System Description
We conducted an underwater field study in order to better understand species –habitat associations within the kelp forest ecosystem. Our study was conducted in the kelp forest located at Hopkins Marine Station, Monterey, California (3637’14.48” N, 12155’06.06” W). This study was purely observational and relied upon the data collected on one day from multiple buddy pairs [[and previous surveys of habitat characteristics]]. The kelp forest at Hopkins extends over multiple habitat types, ranging from sand flats to large, high relief pinnacles and boulders. This habitat diversity is integral to our study as it affects the biogenic habitat formation, as well as the fishspecies that are the focus of our study. This diversity makes Hopkins ideal for our study.
General Approach and Data Collection
Our field study was conducted on open-circuit SCUBA equipment and each transect was observed by a buddy pair. Data for this study was collected via an observational field study using a benthic fish survey.
Each buddy pair observed one benthic 2 meter x 2 meter x 30 meter volume transect in both shallow and deep zones. The duplicate data collected by each buddy of the pair to give an average for each transect. Data was collected in 5-meter long segments, yielding six 2 meter x 2 meter x 5 meter segments per transect. Fish observed within this volume were identified (to the species, if possible) and sized in centimeters. A total of 36 segments were sampled during the study.
Study Design
- HA: Species abundance will be greater within the shallow zone. Our data collection methods will allow us to accurately identify a correlation between species abundance and zone. Each site sampled was broken into two transect zones, allowing for data to be compared between the two zones over the whole sampling site. Dr. Pete Raimondi, PhD, analyzed our data using a chi-square analysis on the raw data to determine the independence of the two variables, species observed and zone. When interpreting our results, we look for points that show dependence between the two variables in order to determine the correlation between species abundance and zone.
- HB: Species accumulation will be greater within the deep zone. Our data collection methods will allow us to accurately identify a correlation between fish species accumulation and zone. Each site sampled was broken into two transect zones, further broken down into smaller segments to allow data to be manipulated to display accumulation rather than simple individual counts over the whole sampling site. Dr. Pete Raimondi, PhD, analyzed our data using re-sampling theory to present the expected number of species as a function of segment number, giving the expected species accumulation based on segment number and zone. When interpreting our results, we look for steep initial slopes and high asymptotes to indicate relative richness and even abundance of a zone [[this isn’t very clear and I think you need to describe evenness …]].
Results [[15/16]]
General Results
In general, we did find a correlation between fish species and zone in the kelp forest of Hopkins Marine Station. We found that these correlations differ between zones as well as between species.
HA: Species Abundance and Zone
We found that most species were more abundant within the deep zone rather than the shallow zone (Value=66.041898, df=18, p<0.000001). By far the most abundant species of all species observed was the pile perch (Damalichthys vacca), exceeding other species in the deep zone by a mean of 4 individuals. Five species were found exclusively in the deep zone, including S. carnatus and kelp perch (Brachyistius frenatus). No species were found exclusively in the shallow zone and were often found more abundantly within the deep zone. Only two species were found more abundantly in the shallow zone, S. chrysomelas and the black-eyed goby (Rhinogobiops nicholsii). See Figure 1 for more details.
The majority of all fish sampled in the deep zone were identified as D. vacca, which comprised over 30% of species identified. In the shallow zone, the percentages of species sampled were relatively even across four species including S. chrysomelas and R. nicholsii, both roughly 15%. See Figure 2 for more details.
HB: Species Accumulation and Zone
Based on our data, we found that over all there is a higher species accumulation in the deep zone than in the shallow. The expected number of species observed over 35 segments for the deep zone was close to 18 species. Comparatively, it is expected that only 14 species be observed in shallow zone over the same number of segments. The species accumulation plot for the deep zone has a greater initial slope and a greater asymptotic value compared to the shallow zone. See Figure 3 for more details.
Discussion [[19/22]]
In our study, we explored the maintenance of fish populations as a function of habitat features, specifically within zones. While our data shows that there is are higher numbers and diversity within the deep zone, there seems to be a correlation with species life history as well.
Data collected from two prior studies in the same month illuminates the relative benthic habitat structure as well as the relative abundance of two macroalgal species, Macrocystis pyrifera and Cystoseira osmundacea. While both species of macroalgae were found more abundantly, but not exclusively, in the shallow zone, the amount of M. pyrifera in each zone is fairly similar. (Figure 4). Within the deep zone, there is less benthic rugosity with nearly half of the bottom being of flat (<10 cm) relief. In the deep zone there are also a greater number of interfaces between sand and other substrate type (Figures 5-6). (Kelp Forest Ecology, Spring 2012. “Swath Survey.”, “UPC Survey.”). Combined with the life histories of kelp forest fish species, these habitat features shed further light on the unpredicted abundance within the deep zone. As shown in a study conducted in the kelp forest of San Onofre, California, fish species not usually associated with low relief substrate interchanges were present in such locations if macroalgae was also present (Larson 1985). The common sand-rock interfaces within the deep zone explain the presence of some species of fish, particularly Sebastes caurinus (copper rockfish), a species that often associates with low relief interchanges of this type (Carr 1991).
Prior studies describing the zonation of fish species corroborate some of our findings, in particular the abundance of S. chrysomelas and S. carnatus. S. carnatus was found only in the deep zone and in relatively low numbers while. On the other hand, S. chrysomelas was found in both zones, though in higher abundance in the shallow zone. Our findings match Ralph Larson’s work describing the depth partitioning habits of these two species (Larson 1980) [[nice]].
The observed species accumulation fits with the prediction as well as with similar studies. In a study by Leon Hallacher, the greatest number of rockfish species was found in depths around 12 meters, similar in depth to our deep site (Hallacher and Roberts 1985). Far more species will be potentially observed in the deep zone, compared to the shallow zone in both studies. The generally larger volume of water combined with ideal habitat may cause the higher accumulation found within the deep zone. Fish species are more able to spread through the water column and the benthic zone, so while there may be less individuals of a particular species, there are more species represented as a whole [[this doesn’t explain the higher densities you observed]].
There were a few aspects of our study that could account for our results, especially in terms of the lower than expected species abundance in the shallow zone. First and foremost, we conducted only a benthic survey of fish species. While this normally isn’t a problem, we included identification and counts of species that are primarily non-benthic. For example, B. frenatus was found only in the deep zone where the literature provides evidence that they populate the upper canopy and water column of reefs around 12 meters (Anderson 1994). Had we coupled our benthic survey with a midwater survey of the same transect, I believe that our results would have been different in terms of species abundance. Another possible problem with our survey was probably human error. This is particularly evident in the counts of D. vacca on the reef that day. While not normally so abundant, there was an extremely large school that crossed several transects and segments so it is possible that there were duplicate counts from several buddy pairs. This alone could account for the higher species abundance found in the deep zone.
Our study of species abundance and richness within the kelp forest both proves and disproves our hypotheses. Contrary to our prediction, there was higher species abundance within the deep zone of Hopkins Marine Station that day. Our prediction regarding species accumulation was correct, however, and more species are expected to live in the deep zone. While both positions are supported by the scientific literature, it is possible that our predictions were incorrect simply because of human error [[this doesn’t really make sense unless you’re just trying to say you were wrong]]. Fish species have also been shown to interact with specific characters of their habitat, both physical and biogenic. This interaction may be unique to Hopkins Marine Station and in order to further our research, similar studies should be conducted at neighboring site with different habitat composition. Coupling new sites with the addition of midwater sampling data will allow us to truly understand the species –habitat interaction at Hopkins and other kelp forests along Central California. This comprehension of the complexities of the kelp forest ecosystem is integral to proper fisheries management, especially for commercially harvested fish such as many rockfish species.
Literature Cited [[5/6 – the year should come right after the author for most citation formats]]
Anderson, Todd W. 1994. "Role of Macroalgal Structure in the Distribution and Abundance of a Temperate Reef Fish."Marine Ecology Progress Series113 (1994): 279-90. Print.
Bodkin, James L. "Fish Assemblages in Macrocystis and Nereocystis Kelp Forests off Central California."Fishery Bulletin48.4 (1986): 799-808. Print.
Carr, Mark. "Habitat Selection and Recruitment of an Assemblage of Temperate Zone Reef Fishes."Journal of Experimental Marine Biology and Ecology146.1 (1991): 113-37. Print.
Hallacher, Leon E., and Dale A. Roberts. "Differential Utilization of Space and Food by the Inshore Rockfishes (Scorpaenidae: Sebastes) of Carmel Bay, California."Environmental Biology of Fishes12.2 (1985): 91-110. Print.
Kelp Forest Ecology, Spring 2012. “Swath Survey.”
Kelp Forest Ecology, Spring 2012. “UPC Survey.”
Larson, Ralph J. "Abundance and Vertical Distribution of Fishes in a Cobble-Bottom Kelp Forest Off San-Onofre California USA."Fishery Bulletin Seattle82.1 (1985): 37-54. Print.
Larson, Ralph J. "Competition, Habitat Selection, and the Bathymetric Segregation of Two Rockfish (Sebastes) Species."Ecological Monographs50.2 (1980): 221-39. Print.
Figures
Figure 1. Species abundance as a function of zone. Means for each species were taken from the total counts from all transects in each zone. Shown in decreasing mean size for the deep zone.
Figure 2. Species composition as a function of zone. Percentages were calculated out of the total of all fish species found on all transects in each zone. The percentages in each zone add up to 100%, but do not total between zones. Shown in decreasing magnitude for the deep zone.
Figure 3. Number of species (species accumulation) as a function of the number of segments sampled for each zone. The initial slopes and asymptotes are the key factors that indicate species richness. Note that these values are predicted, not observed.
Figure 4. Macroalgae density as a function of zone. Percentages between zones add up to 100% for each species. This data was taken from a swath survey conducted earlier at the same site. (Kelp Forest Ecology, Spring 2012. “Swath Survey.”)
Figure 5. Substrate composition as a function of zone. Substrate percentages add to 100% within a zone, but not between them. (SA = sand, CO = cobble, BO = boulder, BR = bedrock). This data was collected in a UPC survey conducted earlier at the same site (Kelp Forest Ecology, Spring 2012. “UPC Survey.”)
[[you lost a figure!?!]]
Figure 6. Relief composition as a function of zone. Percentages add up to 100% within a zone, but not between them. (F = flat, S = shallow, M = moderate, H = high).This data was collected in a UPC survey conducted earlier at the same site (Kelp Forest Ecology, Spring 2012. “UPC Survey.”)