The Symbiotic Relationship Between Zooxanthellae (Symbiodinium) and Upside Down Jellyfish (Cassiopea sp.) Under Different Light Conditions by Jose Deniz and Julia Donaton

 The Symbiotic Relationship Between Zooxanthellae (Symbiodinium) and Upside Down Jellyfish (Cassiopea sp.) Under Different Light Conditions

Jose Deniz and Julia Donaton


Coral reef bleaching is an issue that affects corals globally. Jamaica is not an exception to this. Discovery Bay Marine Lab illustrates a rich biodiversity that allows us to study the characteristics and behavior of such an ecological ecosystem. The lagoon adjacent to the bay is a perfect area to study corals and upside down jellyfish. These species belong to the same phylum of Cnidaria. In fact, both upside down jellyfish and corals have a mutualistic relationship with the symbiotic algae, Symbiodinium, also referred to as zooxanthellae. These are dinoflagellate chlorophyll cells that live in a symbiotic relation with the upside down jellyfish, providing it with nutrients. In order to determinate whether or not upside down jellyfish under extreme condition of darkness present the same characteristic of coral bleaching: expelling the zooxanthellae, four upside down jellyfish were caught for further investigation. Two of those jellyfish were kept in regular light conditions and the other two were kept in absolute darkness. Tissue was removed from all four jellyfish in increments of 24hrs, everyday for seven days. The tissue was dissolved in ethanol and salt water to extract the zooxanthellae, which were then counted and photographed. The data supported our hypothesis, showing overall that jellyfish in the dark had a lower density of zooxantellae present in the tissue than those kept in normal light conditions.



Jose counting zooxanthellae.


Interspecific and Intraspecific competition of Lytechinus variegatus (Variegated Sea Uchin) and Tripneustes ventricosus (West Indian Sea Egg) by Breeanne Thomas and Kaitlyn O’Toole

Interspecific and Intraspecific competition of Lytechinus variegatus (Variegated Sea Uchin) and Tripneustes ventricosus (West Indian Sea Egg)

Breeanne Thomas and Kaitlyn O’Toole

Lytechinus variegatus (Variegated Sea Urchin) and Tripneustes ventricosus (West Indian Sea Egg) are two species of echinoderm grazers found coexisting in Caribbean seagrass beds. According to theory, these species are able to co-exist due to intraspecific competition being higher than interspecific competition. Our experiment tested consumption by the two urchin species, both intraspecifically and interspecifically to see which type of competition would be highest. We collected urchins of both species and similar sizes from the bay. We kept track of their mass and consumption of turf algae over 48 hours in a darkened tank with running water. As the number of species increased, we observed a higher proportion of algae consumed on average for both the West Indian Sea Egg and Variegated Urchin. In trials containing both species, observed consumption was more than the expected. We found that competition had less of an effect on consumption when both species were present, interspecifically, than when a single species was present, intraspecifically. Therefore, competition between different species is less then competition among the same species.

  Abstract Picture

Weighing of West Indian Sea Egg.

Functional Morphology and Reaction to Stimuli in Two Classes of Echinoderms by Farnaz Anwar and Abby El-Shafei

Functional Morphology and Reaction to Stimuli in Two Classes of Echinoderms

Farnaz Anwar and Abby El-Shafei

Upon observation in Discovery Bay, sea stars and brittle stars have been most commonly found under rocks, or more specifically in the absence of light. Two of the classes of Echinoderms, Class Asteroidea and Class Ophiuroidea, are differentiated by the attachment of their arms relative to the central disk. Our research was brought about by our interest in the implications of the functional morphology for these classes of Echinoderms. We analyzed both to see if functional morphology would play a role in the total displacement of the organisms when presented with light, sunscreen, and a failed predator simulation. Each organism was placed at the origin of the experimental tank for a timed duration as it was presented with one of the aforementioned stimuli. The results support the idea that the difference in functional morphology of Class Asteroidea and Class Ophiuroidea play a role in their total displacement. More specifically, the functional morphology of Class Ophiuroidea gives the organisms of this class an advantage when movement is needed to avoid discomfort and predators. Moreover, if an organism has a larger mass, it is more probable that it will be able to move a farther distance than one with a smaller mass if given the same amount of time to do so.


Organisms of the Class Asteroidea and Class Ophiuroidea found in Discovery Bay.

Island biogeography and coral reef patches by Ali and Taylor

Island biogeography and coral reef patches by Ali and Taylor

The Theory of Island Biogeography was developed by ecologists Robert MacArthur and E.O Wilson in the 1960s. It examines how the rate immigration and extinction influence the species richness on an island community. The theory predicts that the rate of immigration fluctuates depending on the how close the island is to other land forms. The closer the island is to the main land, the higher the species richness will be. The theory also predicts that the rate of extinction fluctuates depending on the size of the island. The larger the island is, the higher the species richness will be. In this experiment, the Theory of Island Biogeography was applied to coral reef patches. 12 coral patches were marked and observed, divided into the categories of close and far from the coral ridge “mainland”, as well as small or large based on their surface area. The circumference, height, and rugosity as well as each patches distance from the coral ridge were measured. Each patch was photographed and observed to determine the biodiversity of their algae, sponges and corals. No relationship was found between the sizes of a coral patch, and its biodiversity. There was also no relationship found between the distance a coral patch is from the reef crest, and the biodiversity of the patch. This shows that coral patches do not seem to follow the Theory of Island Biogeography. One reason for this could be that the distances between the coral ridge and the patches were not large enough. Longer term studies will be needed to properly determine the accuracy of this theory. 

Taylor and Ali_ Species richness of coral patches

The richness of coral reefs.

Boring Sponge (Cliona spp.) Population Surveys on Coral Reef Sites in Discovery Bay, Jamaica by E. Markowitz and G. Taylor

Boring Sponge (Cliona spp.) Population Surveys on Coral Reef Sites in Discovery Bay, Jamaica
E. Markowitz and G. Taylor

The boring sponges (Cliona spp.) bioerode live coral and coral rubble by excavating the calcium carbonate from the substrates by chemically etching it away (Holmes 2000). They are known to grow in higher abundances in areas that are experiencing stress. An analysis of species composition showed that distances, and depths within the reefs, on the back reef, and areas not in the reef zone had an effect on clionid community composition (Holmes 2000). Sponge abundance is more greatly effected by factors affecting the reefs as a whole (Holmes 2000). A local anthropogenic stress to coral reefs is believed to be the Bauxite mill in Discovery Bay because of the small sediment discharge and human activity in the area. The boring sponge and coral percent coverages are hypothesized to reflect their proximity to the site. To assess a proxy for stress, sediment size, water clarity, coral percent coverage, boring sponge percent coverage, and coral species richness from each site were analyzed. Sites down the long shore current from the Bauxite mill included Discovery Bay lagoon, Blue hole within the lagoon, and various sites on the Discovery Bay reef crest, sites up the longshore current from the Bauxite mill, and Columbus Park. Sites within the lagoon were at 1.524m (5 feet), Blue hole was taken at 4.572m (15 feet), and all other sites were taken at 9.144m (30 feet). Sites were analyzed for percent coverage by taking photos of a half meter quadrats on a 10 meter transect line. Photos were later analyzed with Coral Point Count with Excel Extensions 4.1 (CPCe 4.1) for boring sponge and coral percent coverage. Sediment will be analyzed for size through ImageJ 1.47v. All samples were analyzed from 17 January 2014 to 21 January 2014. Boring sponge (Cliona spp.) populations will be higher at sites with smaller bottom sediment particle size, lower coral coverage and lower coral species richness. It was found that very small amounts of boring sponge were found in Columbus park where abundances of coral were expected to be lower while boring sponge abundance was expected to be higher. Further analysis and studies can be done to determine the reason for low boring sponge abundance with low coral abundance.


GraceAnne reachcing into the tool bag for bottles to collect a sediment sample at Columbus Park.

Population Distribution of Tripneustes ventricosus in a Coral Reef Lagoon by Salvatore Caldarello & Katarina Norte

Population Distribution of Tripneustes ventricosus in a Coral Reef Lagoon

Authors: Salvatore Caldarello & Katarina Norte

The West Indian Sea Egg, Tripneustes ventricosus, finds habitat in coral reef lagoons at an unequal distribution. Population density and size distribution trends were observed in the natural setting. Three hypotheses were formed upon these observations: population density increased as we approached the reef crest, population density was selective for substrate, and average urchin size increased as we approached the reef crest. Data was collected by 25 meter transect lines in parallel approaching the reef crest. All the Tripneustes ventricosus that lay along the transect lines were recorded on what substrate they reside on and a random subset of Tripneustes ventricosus along each transect were measured. Patterns were interpreted from the data collected including: increasing population density near the algal crest, a preference for coral substrate over grass and grass over sand, and increasing size of Tripneustes ventricosus upon approach of the reef crest.



Finding Tripneustes ventricosus along the transect line

Amphipods and Mangrove Prop Roots by Megan Ladds and Danica Littlefield

Amphipods and Mangrove Prop Roots by Megan and Danica

The amphipod Gammaridae resides in turf algae that covers the prop roots of the red mangrove tree (Rhizofora mangle) in Discovery Bay, Jamaica. Benthic and pelagic organisms prey upon amphipods and their algal habitat. This study focused on benthic predation related to whether the prop root touched the ground or did not touch the ground. If the root touched the ground it would allow greater benthic predation and lead to a smaller amphipod abundance in the root algae. The algae was collected in a 15cm section off of the root. Equal amounts of roots touching and not touching were sampled. The amphipods were counted and the algal biomass was measured. There was no difference in the amount of amphipods per area of algal coverage on the root. However, amphipod abundance was higher per gram of algae on the prop roots that were not touching the ground versus those that were. There was also less algal on the prop roots that were touching the ground compared to those that were. Benthic herbivorous predation on the amphipod habitat as well as predation by omnivorous crabs and shrimp on the amphipods led to less amphipods per gram of algae in prop roots that touched the ground.  


Megan (l) and Danica (r) counting amphipods.

Control of Algae Populations by Urchin Predation and its Effect on Coral Abundance by Richard Ramsundar, Roxane Javadi, and Lucia Kolodiuk

Control of Algae Populations by Urchin Predation and its Effect on Coral Abundance

Richard Ramsundar, Roxane Javadi, Lucia Kolodiuk


Since the 1990’s, Jamaican reef environments have been recovering from a decline in the population of Diadema antillarum due to disease, natural disturbance, and persistent anthropogenic threats. D. antillarum acts as a key algae grazer in conjunction with Tripneustes ventricosis and Lytechinus variegatus. Our study assesses the effects of urchin herbivory on coral abundance through top-down predatory control of algae in reef sites close to Discovery Bay Marine Laboratory. We anticipated that coral cover would be greater in regions of high urchin density and lower in regions of reduced urchin density. Additionally, we expected to find a shift towards algal dominance in areas of low urchin density.

For our study, four reef sites were chosen haphazardly in close proximity to the lab. 12m transects were laid down at each location and photographed in a series of 30cm by 30cm quadrats. Each quadrat was evaluated using the Coral Point Count 4.1 software, which calculated percent coral cover and percent algal cover for each transect. Urchin counts were also taken for D. antillarum, T. ventricosis, and L. variegatus within a 1m radius of each transect line.

Our comparison of urchin population, coral abundance, and algal cover revealed that sizeable algae cover was present at all sites. Each site’s average coral cover ranged between 1.59 and 11.11% while algal cover ranged from 15.84 and 31.97%. As expected, there was a higher percentage of coral cover in sites with higher urchin density. There was no observable trend for the number of L. variegatus in relation to percent coral cover for each site. However, we observed increased coral cover in areas with a greater abundance of D. antillarum and decreased coral cover in areas with a lower abundance of T. ventricosis. Still, our study strongly suggests continues algal dominance within reefs surrounding Discovery Bay.

Rox_Rich_Luc_Abstract Photo

Richard laying down quadrats

 - Richard, Lucia, and Roxane

23 Jan PM – So long to warm weather…

Here's the class on our departure day.  Tanner and smarter!

And we're back in NY!  And it is cold here.  It was difficult to leave Jamaica this morning after one final breakfast of french toast, papaya and pineapple, and blue mountain coffee.  But in a first for this trip, we had bad weather on our departure day. Rain, wind, waves.  I think that's actually a better way to leave the island, otherwise you're wishing you could be diving or snorkeling instead of on the plane.

All the instructors would like to thank this year's class for a great trip. We hope everybody had fun, learned a lot, and is currently getting ready to work on their final research papers which are due in 2 weeks !

We'll be posting each research groups project abstract (one per day) for the next week so check back to see what the student's found from their research efforts.

Profs Peterson and Warren