The
Effects that Surrounding Hard Structures have on Biodiversity and
Abundance Found in Turtlegrass (Thalassium
testudinum) Patches

Hamm,
T., Le.S, and Miller, P.

Abstract

For
our project, we decided to see how structures may influence the
communities in the surrounding turtlegrass
(Thalassia testudinum)
meadows.
This was done by comparing two turtlegrass patches; one relativately
close to significant structures, and one approximately 50 meters
away. Structures include, mangroves (Rhizophora mangle), and dead
coral reefs. Over the course of five days, five samples of turtle
grass was taken daily at each site. We also sampled the populations
of epibenthic invertebrates and fish using five meter transects,
twenty-five meters per site per day. The seagrass samples were
analyzed to determine the number of leaves, number of bite marks, and
epiphytic algal coverage per square meter and meter of seagrass
surface area. The density of bite marks and epiphytic algal coverage
was used as a proxy for (determining a level) of herbivory at each
site. Average abundances of individual species were compared between
the two sites, as well as the Shannon-Wiener index, the Simpson
index, and a dominance curve, in order to compare the diversity and
abundance of species at each site.

Peter diving to conduct a bottom survey.

The Correlation Between Herbivory and Algae Distribution in
Different Areas of Discovery Bay

Algae can be
found in all parts of Discovery Bay, from the mangroves to the fore
reef. Our study aims to look at the correlation between herbivory and
distribution of red, green and brown algae in the mangroves and the
back reef. In the first part of the study a 63 cm by 63 cm PVC
quadrat was used to observe the algal distribution in different parts
of the mangroves and the back reef. We went to the mangroves and the
back reef every day for a week and took pictures of the quadrats in
five areas of each site. Through the pictures and samples that were
collected, the algae and other species in each quadrat were
identified. The distribution of the algae was recorded using the
Braun-Blanquet scale. This uses a scale number to represent a percent
coverage within the quadrat. We recorded the percent cover of no
algae, turf algae, and encrusting algae along with red, green and
brown. For the second part of our study two looked at herbivory on
the algae. We weighed and attached red, green, and brown algae to
tethers put them out at the back reef and the mangroves. These were
out for two 24 hours periods and then reweighed. The results were
recorded and analyzed using a two tailed t-value test.   

Quadrat sampling of bottom cover.

Variegated Sea Urchin Cover Variability
and Predation

Throughout Discovery Bay, it can be
noticed that in different regions of the bay, Variegated Sea Urchin
populations will vary, and they will also cover themselves with
different materials found in their near-by environment. The bay was
divided into three different regions: A, B, and C (Just outside the
Mangroves, at the reef crest, and along the jetty) in order to study
these changes. In each area, Variegated Sea Urchins were collected,
as long as all the material that they were covering themselves with.
The mass and area that this material was covered in was then recorded
to see that the Urchins population was the smallest in region C, but
Urchins in this region were found to have the highest mass and
surface area of covering material on them. The most predation was
also found to occur in region C, while the most variability in
predation occurred at the Reef Crest in region B. It was believed
that Turtle Grass would account for the highest percentage of area
covered on each Urchin, however, Coral Debris was found to account
for the highest numbers.  

Urchin collection.

Grouping
Behavior in Rock-Boring Sea Urchins (Echinometra
lucunter)

Abstract:

Echinometra
lucunter,
or Rock-Boring Sea Urchins, are a species of tropical echinoderm
which are found in abundance in the Atlantic Ocean throughout the
West Indies (Plazas, 2012). Common within rocky intertidal regions
(McPherson, 1969), the urchins burrow into rocks to create their own
shelters, which are continually enlarged as the urchins grow (McLean,
1967), supported largely by a diet of various algal species including
Sargassum
(Plazas,
2012). While swimming in Discovery Bay, Jamaica, we noticed that
these urchins apparently cluster on rocks, with some areas covered
with urchins and others containing few or no urchins, leading us to
ask the following questions: 1. Do E.
lucunter exhibit
grouping behavior? 2. If so, do factors such as abundance of food
and habitat size and availability influence grouping behavior? We
hypothesized that the urchins do exhibit grouping behavior, and that
if faced with the choice, they will cluster around larger habitats
rather than food or smaller habitats. In order to test these
hypotheses, we monitored changes in the spatial distribution of ten
E.
lucunter individuals,
which we placed in an aquarium with a roughly uniform distribution
pattern and then photographed over a specified number of time
intervals under three experimental conditions: no food or shelter,
shelter with no food, and food with no shelter. We then further
tested the urchins' preferences for food vs. shelter and for small
vs. large shelters, in order to determine potential drivers behind
the suggested grouping behavior. We then measured distances between
each urchin and its nearest neighbor, and will analyze this data by
applying the Nearest Neighbor Analysis ("Nearest neighbor
analysis") to determine if the urchins are exhibiting random,
uniform, or clustered distributions. From a preliminary examination
of histograms of our results, it appears possible that Echinometra
lucunter
individuals do exhibit grouping behavior, but there is no discernible
preference for food vs. habitat or for smaller vs. larger habitats.
Statistical analysis is required to determine whether or not these
apparent trends are significant.

The initial setup for our first experiment, testing the distribution
of Echinometra
lucunter
in an environment with no food or shelter.  

Brittle Star’s
Sensitivity to Light and Their Rate of Movement

Our interest in brittle stars began
after the completion of our collection tanks. Most groups had a
collection of brittle stars in their tanks. As we observed them we
noticed they were always found under rocks. After further research we
discovered they were highly sensitive to light and therefore always
seeking shelter to avoid light. We then decided to use them in our
experiment. In the field, we began to notice different patterns of
movement among two species of brittle stars; Ophiocoma echinata
and Ophioderma appressum, more commonly known as the Blunt
Spined Brittle Star and the Banded Arm Brittle Star respectively. We
used both species to determine if light would play a factor in the
brittle stars rate of movement. The rate of speed of both species was
calculated by measuring the amount of time it took to hide from the
light and the distance they moved in that time. We first measured the
rate without adding artificial light to use as a control. Then we
began trials using a flashlight to compare the rates. After, to
further our research, we used colored filters on the flashlight to
change the intensity of light available to the brittle stars. Unlike
the previous experiment, only Ophiocoma echinata was used to
monitor the effects of light filtration. We hypothesized that the
brittle stars will avoid light by moving faster towards a shadow or
some place to hide. When there is a continuous and more intense
source of light present, they will move faster to escape the light.

This was the set up used to calculate
the brittle stars rate of movement.

The Effect of Anemones on the
Spatial Distribution of Marine Life

Anemones use specialized stinging
cells called nematocysts in order to avoid predation. The physical
placement of other marine life in relation to each anemone was
analyzed within a given area. Populations of anemones were split into
three groups: the first group consisted of one anemone, the second
group contained more than one anemone, none of which were touching,
and the third group contained multiple anemones that were all in
direct contact with each other. I expected to find a larger
population of algae and plants surrounding the anemone and a small
number of invertebrates. I found that characteristic species of algae
as well as urchins tended to be present within certain ranges of the
anemones, suggesting that some marine life is better suited within a
given distance from the anemone.  

Quadrat containing anemone.

Coral Disease
frequency and severity in areas of dense population versus disperse
areas

Disease
around the Caribbean, along with anthropogenic causes, is one of the
biggest threats to coral abundance and diversity. Corals have the
propensity to host a large amount of pathogens that can be
detrimental to their health. Because these pathogens include
bacteria, it is reasonable to assume that they follow some principles
of disease movement through populations. We therefore hypothesized
that coral disease is more prevalent and severe in populations of
corals that are more densely distributed than corals that have a
diffuse distribution. We separated our groups based on the reef
structure. We then proceeded to transect the two areas with a 15
meter line with a width of 1 meter either side of the transect line.
Using the Braun Blanquet scale, we measured the severity of the
disease if the coral was infected. The
data we collected shows that there is no statistically significant
difference between the aggregate number of diseased coral in the
patchy areas compared to the dense areas The severity increase that
we expected to see in the dense area coral was also statistically
insignificant, suggesting that coral density has little to do with
disease severity.

Example of black spot disease on Massive Starlet Coral (Siderastrea
sidereal).

Difference in
degree of complexity of habitat structures and their effects on
biodiversity in various back reef habitats.

Cuison, A. and
Perez, C.

Abstract

This
experiment aimed to show the effects of an addition of habitat
structures of different spatial complexity to three back reef zones
with various degrees of natural complexity. A simple structure (215
cmᶟ)
and a complex structure (862 cmᶟ)
were created in order to show how the difference in area for
inhabitation would affect biodiversity in three distinct environments
within the back reef. After assessing the location, a metric of
comparison was created in order to place the different back reef
environments of sand flat, seagrass, and patch coral into three
categories based on the natural complexity they provide (1-3
respectively). Once the environments were split into the categories,
each was provided with one of each of our simple and complex
structures. The structures at each site were situated linearly 10
meters apart from one another and the three sites were around 20
meters apart. The structures were observed once daily in the morning
and all the species living within the structure, within 2 meters of
the structure and those who visited the structure (>5 seconds)
were recorded. After one week of observations we found that the sand
flat area had the greatest number of inhabitants and the most
immigration of diversity while the patch coral had equal success in
abundance but diversity was only redistributed among the new complex
structure and the naturally occurring complexity of a reef system.
This tells us that in an area lacking all natural complex structures,
organisms will be attracted to and therefore more inclined to inhabit
any additional structure provided. However, in a natural habitat that
is teeming with complexity, organisms have a tendency to congregate
in that one area and are then inclined to move from structure to
structure as opposed to any new diversity migrating in.  

Damsel in structure.

 Sedimentation and its Effects on
Chlorophyll A Production in High and Low Microbial Sponges

After observing
the various different species of sponges that inhabit the tropical
Caribbean reefs around Jamaica changes in chlorophyll levels were
anticipated between them. Microbial concentrations were determined
and inferences were made that sponges with higher microbes would
produce larger concentrations of chlorophyll A. This week long
experiment looked at sedimentation as well as suspended particles in
the water column to determine whether or not they affected the
microbes and their chlorophyll A production. Due to constraints with
sample sizes and limited field time we were unable to significantly
prove our hypothesis with statistical analysis. However our results
state that there was a marginal significance (p=0.054) between high
microbial sponges and their chlorophyll A production. There was no
direct correlation between sponge surface area and volume to
chlorophyll A concentrations.

Aplysina fistularis

Research Group (Left to right Amy
Marshall, Ben McKeeby, & Kevin Ryan)

Samantha Silvestri and Allie
Gale 

The Effect of Diet
on Ink Response and Replenishment in Aplysia
dactylomela

When threatened, the spotted sea hare
A. dactlyomela will release a deep purple ink as a defense
mechanism to deter predators. Each individual only has a limited
amount of ink in its ink gland, which it releases in rationed
portions each time it inks. Previous studies suggest that it takes
approximately two days for A. dactylomela to replenish its
ink reserves after completely depleting its supply. Our study tested
two groups of four sea hares each: a control group that was fed 205g
of the red algae Gelidiella acerosa daily and an experimental
limited-diet group that was fed 50g daily. Our experiment aimed to
see if there was a relationship between a restricted diet and ink
response time to a fabricated threat, as well as to test how quickly
A. dactylomela can replenish its ink reserves after inking.
We hypothesized that the sea hares that consumed a limited diet would
take a longer time to replenish their ink reserves and would not be
able to ink as frequently as those in the control group. We tested
our hypothesis by picking up and lightly jostling each sea hare for
up to one minute until it inked. This process was repeated every two
minutes for eight minutes, and the procedure was conducted every
twelve hours over the course of seven days. We found that the average
ink response time for each sea hare increased over the course of
eight minutes, and the number of inking events significantly
decreased in both groups throughout the eight minute trial. The
limited diet group on average stopped releasing ink earlier in each
trial than the control group. Our study supports the claim that sea
hares that consume a limited diet have a reduced inking frequency and
increased ink response time, though further research is required to
determine whether this is due to habituation or complete depletion of
ink.

Aplysia dactylomela releasing
ink during a trial