Differential Habitat Utilization by the Sessile Invertebrate and Algae of Hopkins Marine Station

Differential habitat utilization by the sessile invertebrate and algae of in the kelp forest at Hopkins Marine Station [[3/4, nice clear title that gets at the larger ecological question and identifies the study location, but should also identify the study system]]

Zach Randell

[[9/14 Overall Clarity – you’re writing is missing a lot of the connections between ideas and sentences, making it a bit difficult to follow - line-by-line edits provided for the intro only, try to apply these concepts to the rest of the paper and consider in your future work.

• Don’t use jargon, where a simpler word would achieve the same thing, and definitely don’t use any words if you don’t understand what they mean!
• Make sure each sentence has a clear subject and a verb (i.e. a PERSON/THING that is DOING something) to avoid passive voice and make your writing easy to understand.
• Carefully review rules of punctuation and learn how to use commas, colons, and semi-colons correctly.
• Try varying sentence length for a mixture of longer sentences that connect multiple concepts and short sentences that make a single clear point.
• Don’t forget to connect the dots between ideas, just because you understand how two ideas presented in adjacent sentences are related, does not mean it’s clear to your reader.
• Call on your classmates to proof read for you! They can help identify where your writing is unclear so that you can fix it BEFORE you turn your paper in!]]

Introduction [[9/20 This introduction could be improved by: 1) beginning with the big ecological question, how diversity is maintained in the face of interspecific competition, and using the scientific literature to create the context for this question, 2) identifying how this study addresses questions about niche diversification and resource partitioning, 3) introducing the clear and specific questions this study was designed to address and their associated hypotheses (in paragraph format), 4) explaining why the kelp forest is a good study system to address these questions, and 5) addressing why your study is novel and adds to the field of ecology.]]

[[begin by introducing the big ecological question about how diversity is maintained and similar species can coexist without one species driving the other to extinction through competition]] Benthic substrate composition and subsequent differences in habitat utilization yield varying levels of species abundance. Marine invertebrates and algae continuously compete for a limited supply of substrate suitable for recruitment. (Dayton, 1971). [[the reference belongs within the sentence to which it is referring]] Niche partitioning fosters diversity among species with similar life history requirements by limiting competition for a shared resource. (Leibold, 1995). [[explain how niche partitioning limits competition rather than just saying that it does]] Understanding different forms of habitat and associated species may offer insight into mechanisms driving niche diversification and thus the maintenance of diversity. [[how?]]

Economically, accurate knowledge of habitat associations is critical for effective enactment of marine protected areas. [[how is this about economics?]] Applying benthic habitat composition with known fish ranges and respective habitat associations may foster more informed decisions for fishery management and stock preservation. Unfortunately the difficulty associated with studying marine communities has slowed our understanding and yet beckons further inquiry. [[I understand what you’re getting at, but you haven’t created strong links between these ideas.]]

Macrocystis pyrifera is a habitat modifier shown to increase species diversity in marine communities. (Bodkin, 1988), (, Braken et al.,2004). Thick stipes leading to blanketing canopies provides refuge and structure comparable to terrestrial forests. Hopkins Marine Station harbors a highly productive and diverse kelp forest communities community fueled by nutrient rich upwelling events out of MontereyCanyon. [[I’m not sure the canyon has anything to do with upwelling, and actually there isn’t really much upwelling at Hopkins itself, but there IS nutrient-rich water]] Various A variety of substrates substrate types and vertical relief provide variable spatial habitat for hosting numerous different types of organisms. Exhaustive subtidal observations spanning nearly two hours provided all data for analysis. Through uniform point contact surveys [[describe briefly what you recorded]] we sought to uncover associations between species abundance, substrate type, and with habitat relief and substrate, while teasing apart the relative importance and contribution of both upon species diversity. [[did you really look at diversity? I think you looked just at the associations between habitat characteristics and the abundance of different organisms and your findings may support the theory that niche diversification is supporting high diversity in the kelp forest]]

Methods [[8/18 - The methods section should begin by briefly describing the general approach (observational, UPC method to characterize primary substrate holders, substrate type, and relief). Then talk about the system and expand on why it’s a good site for this study (something that should be introduced in the intro). Then you need to identify the specific hypotheses and explain how your data collection methods will allow you to test each hypothesis. After you’ve explained WHY you did things the way you did, you want to provide a detailed description of methods, including data analysis. The figures are a nice touch, but you may not need all of them]]

Hopkins Marine Station in MontereyCalifornia served as our study site. (36° 37’ 17.02” N, 121° 54’ 07.28” W) Shore entry allowed quick access to a 270 meter permanent cable running roughly North-West offshore through a Macrocystis pyrifera forest. Rock outcroppings and boulders interspersed with sand patches dotted the region around the cable. Cystoseira osmundacea and Dictyoneurum californicum both were observed in addition to a wide variety of unidentified red, crustose and articulated coralline algae species. Nestled just inside of Monterey Bay Hopkins has a reprieve from South swells while West and North movements may be noticeable. Surge was mild during all observations on April 4th 2012. [[site description should be made relevant to the study, especially why it’s a good place to do this kind of study]]

Figure 1: Hopkins Marine Station

Fig. 1. A buoy marked the 100 meter mark on the cable signaling a drop point for all 20 subtidal observers. Working in teams of two along the cable observers located a pre-assigned meter marker (90 m – 135m, 5m increment, 10 tie-off points total) indicating the appropriate place to initiate sampling. Each buddy pair executed two transects over two dives. One transect offshore (90°, “deep”) and one transect inshore (270° “shallow”) of their respective meter mark. The 30 meter tape was divided into twelve consecutive 2.5 meter increments. Each diver was responsible for every other 2.5 meter increment. The staggering of observational regions allowed tabulation of inter-buddy sampling variation. Each 2.5 meter segment consisted of five 0.5 meter increments whereupon four distinct observations were gathered at each point.

[[before getting into the details, describe the general approach and then how you used specific methods to address each hypothesis]] Uniform point contact (UPC) required the observer to note substrate, physical relief, primary substrate holder and drift algae/laminarial presence for six 2.5 meter stretches, with 5 points within each 2.5 meter increment. The four assigned observations yielded a cumulative 120 points on the data sheet for one observer on one transect. A total of 240 points were gathered for a single transect upon incorporation of the other buddies 2.5 meter increment assignments. 20 transects totaling 600 meters of benthic habitat were classified and quantified [[good instinct to get the total number of meters of benthic habitat, but the most relevant is the total number of data points you had for your analyses (1200?)]].

The substrate was observed and tabulated into four categories – sand, cobble (rocks with a diameter less than 10cm) boulder (rocks with a diameter less than 1 meter) and bedrock (any hard substrate greater than 1 meter). Substrate composition allowed inference into habitat preference when combined with other benthic data.

Figure 2: Relief Sampling [nice use of a figure, the figure title and description should occur together, though]]

Fig. 2. Relief measures the greatest vertical change within a one meter wide by 0.5 meter length window looking down upon the transect tape. Relief is grouped into four categories. Flat: 0-10cm, low: 10cm- 1m, medium: 1-2m and high: greater than 2m. Combined with the previous substrate category, relief allowed the habitat composition and structure analysis to be mapped into a 30x1x2 meter window.

Table 1: Primary Substrate Holder Groupings and Species [[I like the table]]

Table 1. Primary substrate holder was sampled directly under each 0.5 meter mark along the transect tape (60 per 30 meter transect). It is defined as the object directly attached to the substrate underneath. Inanimate objects, red algae, brown algae, coralline, tube worms, snails, cnidarians, and tunicates all occupy categories of identifiable primary substrate holders. UPC accounts for species that are uncountable (colonial tunicates) or impractical to count (cup corals) on an individual basis. Percent coverage of each category or species can be quantified from the 60 unbiased primary substrate holder observations gathered for each transect. The presence of drift algae and juvenile laminarials too young to be reliably identified are both noted as a fourth category. Drift algae may provide a microhabitat and its presence or absence is noted then swept aside to observe the primary substrate holder. [[a lot of this information doesn’t belong in a figure caption, which should really just say something like “the categories of primary substrate-holder species sampled and recorded during UPC surveys”

Associations were compiled by the calculation of deviation from expected if species abundance was determined by random chance. Strong associations indicate a species is disproportionately either present or absent from a given substrate or relief. Strength of association varies from strong, medium to low. [[you should describe the analyses in a little more detail]]

Results

[[7/16 - you actually need some TEXT here, not just figures! Your results section would be improved by inclusion of: 1) text describing general results (from first two graph pages that Pete presented, 2) description of the results relative to each hypothesis including whether associations were positive or negative and whether or not the results supported your hypotheses, and 3) better figure formatting and less detailed captions (try using a 1x2 table for your figures with the actual figure/table in one cell and the caption in the other an combine all the figures into a single section, either within the results section or at the end of the paper to avoid formatting problems and interrupted flow)]]

Figure 3: Relief and substrate percentage composition

Fig.3. Sand and bedrock were the most prevalent substrate - 40% and 35% respectively. Cobble and boulder trailed with 7% and 18%. Relief was predominately flat and shallow - 39% and 40% respectively. Medium and high relief made up 15% and 5% of substrate sampled.

Figure 4: Substrate and relief associations

Fig. 4. Sand substrate was overwhelmingly associated with flat relief. Bedrock and boulder shared similar trends throughout low, medium and high relief with bedrock consistently enjoying a greater percentage over boulder. Cobbles lack of presence yielded small associations with all relief.

Figure 5: Strong relief associations Figure 6: Moderate relief associations

Fig. 5 and Fig. 6. Sessile invertebrates were found to exclusively have strong positive associations with high relief. Cup corals and Phragmatopoma californica exhibited strong associations, while anemones and colonial tunicates were found to have moderate associations with high relief. Algae exclusively displayed strong positive associations with low and medium relief. Articulated coralline, flat branching red algae, crustose coralline, Dictyoneurim californicum, and leafy red algae all displayed strong positive associations with low and medium relief. Desmerestia spp, Macrocystis pyrifera hold fasts, solitary tunicates, Serpurlorbis squamigerus and sponges all displayed medium associations to low and medium relief. Diopatra ornata, sand, and shell debris displayed strong associations with flat relief. Lacy red algae yielded a moderate association with flat relief. [[many of these details belong in the text of the results, not your figure caption]]

Figure 7: Strong substrate associations

Figure 7: Analysis for bedrock yielded strong positive associations with barnacles, flat branching red algae, colonial tunicates, Corynactis californica, crustose coralline, cup corals, encrusting red algae and Macrocystis pyrifera holdfasts. Strong positive associations with boulders were found for articulated coralline, flat branched red algae, crustose coralline and leafy red algae. Diopatra ornata, sand, shell debris and lacy red algae were all found to have strong positive associations with sand substrate.

Discussion

[[11/22 – you do a pretty good job of relating your results back to your hypotheses, but you could be more explicit about whether or not those results supported they hypotheses. To improve the discussion, you should: 1) go into more detail about suggested mechanisms for the results, in this case, WHY might certain species-habitat associations exist and HOW might they be maintained, 2) use the scientific literature to provide context for your results (i.e. compare to previous similar studies including AT LEAST 2-4 citations in the discussion, not all of them from readings and lectures!), and 3) state overall conclusions and their implications for our ecological understanding and for informing management. ]]

Substrate associations:

Significant differences were not discernible from observer bias post analysis for substrate associations of boulder and bedrock [[I do not understand what you’re trying to say here]]. Strong positive associations for algae were found on both boulder and bedrock, while invertebrates displayed strong positive bedrock associations. (Fig. 7) The difference between boulder and bedrock is likely of negligible consequence at Hopkins where a few centimeters may be the deciding factor between the tallying of either substrate. The similarity in species diversity on boulder and bedrock suggests that the type of rocky substrate is less important than the physical structure formed by that substrate in relation to the surrounding benthic habitat. [[good job getting at a broader conclusion]]

The low percentage of cobble (Fig. 3) manifested weak interactions insufficient to draw conclusions. (Fig. 7) The importance of rock over sand substrate is supported by the overwhelming positive associations with either bedrock or boulder and corresponding negative associations with sand. However, sand substrate shared strong and medium positive associations with flat relief for Diopatra ornata and lacy red algae. (Fig. 5, 6 and 7) The resulting implications for species diversity are explored below as the respective contributions of substrate and relief are analyzed.

Relief associations:

Differences in habitat utilization are apparent upon comparison of algae and sessile invertebrate associations with relief. Algae are strongly associated with low and medium relief while the invertebrates occupy high relief. (Fig. 5) Maximization of UV exposure may be achieved through algal recruitment upon flatter surfaces. Regions of high relief are likely shaded for parts of the day as the sun traverses the sky. Algal settlement to regions of high relief, if present, may be outcompeted by invertebrates or fail to mature due to insufficient UV exposure [[is it UV, or just light generally?]].

Lack of strong invertebrate association on low and medium relief is either due to competition with algae or specific spatial habitat utilization in response to life history requirements. Invertebrates outcompeted by algal species on flatter surfaces may be restricted to regions of high relief less desirable to the dominant algal competitors. Phragmatopoma californica and cup corals (Fig 5) both rely on a constant food supply of phytoplankton and other organic material in the water column. (Palwick, 1986) Habitat with high relief likely experiences greater water flow due to the channeling of water around the obstruction. Stylaster californicus, while absent from Hopkins, is an example where very high water movement is required for successful recruitment. (Love et al, 2010) A pluralistic experimental design with algae, invertebrates, UV exposure and water movement may reveal a mechanism behind the observed differences of habitat utilization. Whatever the mechanism, benthic substrate with varied relief supports greater diversity compared to uniform substrate.