Tropical Marine Ecology 2013

Lauren Marrero, Tara McPhillips, and Kayleigh Boose

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.

Emily Madsen

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.

Dan Hadler and Amir Rashed

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).

Aaron Cuison and Clara Perez

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.

Amy Marshall, Ben McKeeby, and Kevin Ryan

 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

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

21 Jan - Snow ?

Now that we've all been back in NY for a couple of days and have hopefully adjusted to non-80F water/air temperatures, Brad and I (and Amber) would like to thank all the students in this year's MAR 388 course for an excellent effort during the course.  We'll be posting all of the project abstracts here so you can see what the students found out during their research.

Profs. Joe and Brad

18 Jan AM - Last Full Day at DBML

Last Full Day at DBML

We are set to head to the airport around noon tomorrow, so today everyone is finishing up their projects, preparing for tomorrow’s final presentations, and trying to enjoy the last bits of sunshine and warm weather before heading back to New York. Last evening, a few of the newly certified divers took their first night dive past the reef crest, and were able to see spiny lobsters, a huge princess parrotfish, and bioluminescent organisms, and this morning, the rest of the divers took a final trip all the way to Runaway Bay, a short trip east of Discovery Bay. All of our experiments have to be done by four o’clock this afternoon, and following cleanup myself and a few others are planning to take one last snorkel out to the reef crest for some photos and (hopefully) some lovely shells. Much of the rest of the evening will be spent analyzing the data we have collected over the past week and packing for our flight. The past sixteen days have flown by, and I know I am not the only surprised that it’s already time to leave!

Susan and Peter hard at work scraping algae for their research project.

Tracey sorts through samples while Amber reviews the final dive logs.

- Lindsay

18 Jan AM - Tying Up Loose Ends

Tying Up Loose Ends

The second to last day here at Discovery Bay is by no means a relaxing day off as everyone in scrambling to get their trials and final presentations completed as well as the five best pictures we must submit all before breakfast the next day. I firmly believe everyone on this trip will be sad to leave Jamaica, however we have all missed some of the commodities which we take for granted found back home. I know the first thing on my to do list when I arrive back in New York (besides working on my research paper) is to get some pizza and take a nice and long, hot shower! Preparing to embark on my journey back home has inspired me to reflect on all of the spectacular adventures and journeys I have shared with all my newly acquired friends. Looking back I can only hope that I will have the privilege of experiencing another vacation and/or research trip as rewarding as this in the future.

Me observing Rock-boring Urchins for one of our experiments.

Mike putting together his final presentation.

Nick cleaning out his wet lab before 4pm.

- Kyle

17 Jan PM - Breakin’ it Down and Packin’ it Up

Breakin’ it Down and Packin’ it Up

Today was the last day to run our experiments. Everyone has been running around gathering final data and breaking down their experiment setups. My groups experiment was set up in the field testing habitats in the back reef. We had originally set our experiment earlier in the week using a boat and Mr. Scarlett’s Scuba Diving Skills. Today the boats were being occupied by professors for their own projects. Luckily my group had just gotten scuba certified. We swam out with all our gear to break down all our equipment. Even though we brought floats, we had to carry over 100lbs more than a quarter of a mile back to shore. Me and my Partner were half choking through our snorkels barley afloat swimming for our lives. Once we were on shore we were glad that it was over. The rest of the day was spent looking at species which had inhabited our gear that we had never seen before. The tiny Grass Squid (Pickfordiateunthis pulchella) was spotted inking at us while we uprooted its home. There were also angry crabs and even a mysterious fish that our professors couldn’t identify.

Aaron demolishing their Reef Condos!

“Don’t Take my Home!” says the crab Mithrax sculptus

Ten Jamaican Dollars to anyone who can identify this fish!!

- Aaron