Download Niche diversification of sessile organisms at Hopkins Marine Station

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Niche diversification of sessile organisms in the kelp forest at Hopkins Marine Station in
Monterey, CA [[3/4 good job including the big ecological question in the title, but should also
include the study system (a kelp forest)]]
Jonah Mulski
[[9/14 - Overall Clarity – I found your writing difficult to read because many sentences were
overly convoluted and the main ideas were not easy to pick out- 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 semicolons correctly.
 Carefully choose your connecting words (e.g. whereas, while, however, in contrast, thus)
so that they are appropriate to the sentence, because each of these words means
something slightly different.
 Read your sentences out loud to yourself (you’ll only look a little crazy) to make sure that
they flow naturally and are not broken into too many unnecessary clauses; if they don’t
flow naturally try reordering the clauses/ ideas.
 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 [[13/20 This introduction could be improved by: 1) introducing the big question
about maintenance of diversity in the very first sentence, 2) articulating the questions and
hypotheses in a paragraph that is easy to read (and making sure they make sense), and 3)
addressing the novelty of the study.]]
In the competing theories of how species diversity is maintained in ecosystems there are two
main theoretical categories, equilibrium and non-equilibrium theories. [[a broader introductory
sentence about the importance of understanding the factors that maintain species diversity, would
be better here. THEN you can go into different theories about how this diversity is maintained]]
In non-equilibrium theory it is the continually changing abiotic conditions that maintains species
diversity and prevent one species from out-competing and dominating the ecosystem. In contrast,
equilibrium theories are based in the idea that communities return to a state of species
equilibrium after a disturbance and species diversity within the community is maintained by
other mechanisms (Connell 1978). Niche diversification is a prominent equilibrium theory.
According to this theory, species diversity is maintained through the evolution of specializations
that allow species to partition limited resources in such a way as to minimize interspecific
competition (Diamond 1975). To better understand niche partitioning ecologists have studied
species habitat associations and the factors that maintain those associations. [[Good use of the
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literature to put the questions this study addresses into the broader context. You clearly
understand the concepts, but work on simplifying your sentences so that others can understand
them too. Try reading sentences out loud to yourself and try flipping them around to avoid the
need for many commas.]]
The rich species diversity and abundance found in California’s kelp forests makes them a good
system to further the understanding of niche partitioning. Within this system sessile marine
organisms are particularly easy to study due to their lack of movement and the ease at which they
can be counted. For these organisms space on the benthos is a critical resource, their survival and
reproduction depends on their physical location and the amount of space they can occupy.
Previous studies in this system have showed that species spatially segregate themselves to
specialize in a particular type of prey (Watanabe 1984, Hallacher and Roberts 1985). Whereas
sessile organisms may compete for prey, the competition for space seems to be more immediate
when settlement is occurring. [[explicitly create the link between competition for space and how
this contributes to niche diversification]] With the presence of strong interspecific competition
the theory of niche diversification predicts that sessile species would spatially segregate
themselves according to different characteristics of the benthos, in order to reduce competition.
[[notice how I switched things around in this sentence so it reads more smoothly.]]
This theory led us to ask the following questions [[this should be a paragraph that explains both
the questions and the hypotheses]]:
Question 1
Do sessile species segregate themselves according to a particular substrate type?
General Hypothesis 1: There are patterns of association between species presence and substrate
type.
Specific Hypothesis 1: Species will have a higher relative abundance on a type of substrate than
the relative abundance of that substrate in the area being sampled. [[not clear!]]
Question 2
Do sessile species segregate themselves according to a particular relief?
General Hypothesis 2: There are patterns of association between species presence and relief.
Specific Hypothesis 2: Species will have a higher relative abundance on a type of relief than the
relative abundance of that relief in the area being sampled.
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Question 3
If species do segregate with respect to a particular substrate or relief, is one association stronger
than the other?
General Hypothesis 3: There will be a difference in general strength of associations: species and
relief vs. species and substrate
Specific Hypothesis 3: One association, species and relief or species and substrate, will have a
greater number of categories with strong associations than the other.
Methods [[7/18 - 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.]]
We conducted our study on a rocky reef 150 meters offshore of Hopkins Marine Research
Station in Monterey, CA (36° 37’ 15.00” N, 121° 54’ 07.00” W). All the surveys for this study
were completed on April 10, 2012 between 9am and 12 pm along a permanent underwater cable
(marked every 5 meters) that sits in approximately 10 meters of water and runs north and south.
Using SCUBA, two separate 30 meter surveys originating from the cable and running out at 90°
(survey 1) and 270° (survey 2) were conducted in 5 meters intervals between the 90 and 135
meter marks on the cable. On each transect, each buddy in a buddy pair sampled 2.0 meters of
each 5 meter section, one sampled the first 2.0 meters (e.g. from 0 to 2.0) while the other
sampled the second 2.0 meters (e.g. 2.5 to 4.5). We took samples every 0.5 meters using uniform
point contact (UPC), a method in which a sample is taken at the point directly below a meter tape
at predestinated intervals (in this case every 0.5 meters). At each point we took three samples,
one each for cover, substrate, and relief (table 1).[[this detail is good, but belongs lower down in
the methods and isn’t quite sufficient to allow me to replicate this study]]
[[you should introduce the specific hypotheses and how the methods enable you to test each]]
We coupled each species or species group with the substrate it was on and, separately, with the
relief of that substrate. The strength of these associations was quantified by their deviation from
that which would be expected by random chance. They were then categorized as strong
(deviations >2 or <‐ 2), moderate (2> deviation >1, ‐2< deviation <‐1), or weak (all other
deviations) associations. A strong association means that the relative abundance of that species
or species group on a particular substrate or relief is greater than would be expected by random
chance alone.
Results
[[5/16 - would be improved by inclusion of: 1) general results (from first two graph pages that
Pete presented, 2) more detailed 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) inclusion of figures (WHERE ARE THEY?!?) with appropriate formatting
(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)]]
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Question 1
Do sessile species segregate themselves according to a particular substrate type?
General Hypothesis 1: There are patterns of association between species presence and substrate
type.
Specific Hypothesis 1: Species will have a higher relative abundance on a type of substrate than
the relative abundance of that substrate in the area being sampled.
Strong associations: 5 boulder, 8 bedrock, 2 sand
We found that fifteen species or species groups have strong associations with a substrate type,
therefore we reject the null. [[you should describe all this in paragraph format]]
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Question 2
Do sessile species segregate themselves according to a particular relief?
General Hypothesis 2: There are patterns of association between species presence and relief.
Specific Hypothesis 2: Species will have a higher relative abundance on a type of relief than the
relative abundance of that relief in the area being sampled.
Strong associations: 1 flat, 3 shallow, 4 moderate, 2 high
We found that ten species or species groups have strong associations with a relief type, therefore
we reject the null.
Question 3
If species do segregate with respect to a particular substrate or relief, is one association stronger
than the other?
General Hypothesis 3: There will be a difference in general strength of associations: species and
relief vs. species and substrate
Specific Hypothesis 3: One association, species and relief or species and substrate, will have a
fewer number of categories with strong associations than the other.
We found that the association between species and substrate has a fewer number of categories
with strong associations than does species and relief, therefore we reject the null.
Discussion
[[13/22 – You did a good job of tying the discussion to particular conclusions, but you could
improve by: 1) speculating on why results supported or did not support your hypotheses,
including problems with your study design that may have influenced your results, 2) provide
more detail on mechanisms for the results, including HOW species-habitat relationships might
they be maintained, 3) 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!).]]
Question 1
Do sessile species segregate themselves according to a particular substrate type?
General Hypothesis 1: There are patterns of association between species presence and substrate
type.
Specific Hypothesis 1: Species will have a higher relative abundance on a type of substrate than
the relative abundance of that substrate in the area being sampled.
The strong associations we found between species and substrate suggest that species prefer one
type of substrate over another. However, the majority of the strong associations we found are
associations with boulders and/or bedrock, only two, Dioparta ornata and lacy algae, are
strongly associated with sand.
In the dynamic marine environment in which wave energy is often strong, a hard, mostly
nonmoving substrate, like boulders and bedrock, on which disturbance is less likely is clearly
desirable. This is reflected in our data in the larger number of strong associations between
species and boulders, and species and bedrock. This desirability likely makes competition for
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space on these substrates strong. In contrast, competition for a highly mobile substrate like sand
is likely weak. To avoid competition for space on hard substrate but still take advantage of the
abundance of food and nutrients associated with kelp forest, a filter feeder like Dioparta ornata
may have evolved adaptations that allow it to live on a less desirable substrate like sand, a niche
that appears to be relatively open.
Although a few species may have evolved adaptations to take advantage of alternative substrates,
it appears that the advantage of attaching to a hard substrate overwhelms any competitive release
gained by evolving adaptations to take advantage of a less used, more abundant substrate like
sand.
Question 2
Do sessile species segregate themselves according to a particular relief?
General Hypothesis 2: There are patterns of association between species presence and relief.
Specific Hypothesis 2: Species will have a higher relative abundance on a type of relief than the
relative abundance of that relief in the area being sampled.
The strong associations we found between species and relief suggest that some species prefer one
type of relief over another. However, unlike associations with substrate, the strong associations
we found between species and relief are more variable among the categories (flat, shallow,
moderate, high) in which the association occurs. This variability suggests that species have
partitioned the relief in order to minimize competition for structurally solid habitat, i.e. niche
partitioning with respect to relief has occurred.
Again, in the dynamic marine environment in which wave energy is often high, a substrate on
which disturbance is less likely is desirable. The competition resulting from this desirability may
have promoted the evolution of specializations that allow species to partition solid substrates,
like boulders and bedrock, by the types of relief found within those substrates. For example,
Balanophyllia elegans are strongly associated high relief, while leafy algae and branched algae
are strongly associated with moderate and shallow relief, respectively. All three are also strongly
associated with boulders and/or bedrock substrate. By taking advantage of hard substrate relief
on which leafy and branched algae are less abundant, Balanophyllia elegans’s strong association
with high relief allows it to reduce any competition for space it may have experienced (e.g.
access to hard substrate with adequate water flow in which to feed) with these algal types, while
still gaining the benefits of a solid substrate type.
Question 3
If species do segregate with respect to a particular substrate or relief, is one association stronger
than the other?
General Hypothesis 3: There will be a difference in general strength of associations: species and
relief vs. species and substrate
Specific Hypothesis 3: One association, species and relief or species and substrate, will have a
greater number of categories with strong associations than the other.
The number of relief categories (flat, shallow, moderate, high) in which strong relief associations
occurred suggests this association is weaker than that between species and substrate. The
diversity of relief categories seen suggests that one particular type of relief is not overly critical
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for survival, thus organisms have been able to specialize via relief in order to minimize
competition for space while still taking advantage of structurally solid habitat. The lack of
diversity seen among the strong associations with substrate suggests that structurally solid habitat
is critical to the survival of many organisms, thus niche partitioning with respect to substrate
types is not as common.
While we looked for niche partitioning associated with relief and substrate, there are many other
factors that, due to time and logistical constraints, we did not look at (e.g. feeding preference
and/or time, life history traits like timing and reproduction method, predation, competition). For
species with moderate associations it appears that niches associated with relief and substrate are
important in determining their distributions but these overlooked factors may take precedence.
For species that we found to have weak associations factors other than those associated with
relief or substrate may be more important. Alternatively, their distributions may be random due
to the lack of competition for resources (Connell 1978). Further study in this area is needed.
For all the species we found to have strong associations it appears that their associations with a
particular substrate is so great it hasn’t allowed niche partitioning to occur. However, it seems
that niche partitioning has occur with respect to this ‘essential’ resource, as seen in the
associations with relief. This suggests that the need for an ‘essential’ resource is so great, like the
need for structurally solid habitat in near shore marine environments, that alternative niches can’t
be exploited, even if the potential for release from competition exists, an attribute sandy habitats
in kelp forests may offer.
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References [[4/6 -at LEAST 6 references were required for this assignment]]
Connell, J. H. 1978. Diversity in Tropical Rain Forests and Coral Reefs. Science 199:1302-1310.
Diamond, J. 1975. Ecology and Evolution of Communities, Belknap, Cambridge, Mass.
Hallacher, L. and D. Roberts. 1985. Differential utilization of space and food by the inshore
rockfishes (Scorpaenidae: &lt;i&gt;Sebastes&lt;/i&gt;) of Carmel Bay, California.
Environmental Biology of Fishes 12:91-110.
Watanabe, J. M. 1984. The Influence of Recruitment, Competition, and Benthic Predation on
Spatial Distributions of Three Species of Kelp Forest Gastropods (Trochidae: Tegula).
Ecology 65:920-936.
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