Phenotypic plasticity

Sponges are sessile marine organisms that have developed efficient defense mechanisms against microbial pathogens. These organisms are one of the most promising sources of antibiotic pharmaceutical products derived from the ocean. As human infectious microorganisms evolve to become more resistant to our current antibacterial medications, the medical community has developed an increased interest in the use of sponges for novel medications. This study aims to provide a basis for the collection of sponges to be used for pharmaceutical purposes. Sponges have shown variation in antimicrobial compounds due to changes in their environment, such as increased temperature or depth. This study analyzed variation in antibacterial properties based on proximity to a pollution source. Samples of three Caribbean sponges, Pseudoceratina crassa, Aplysina archeri, and Holopsamma helwigi, were taken from areas of low relative pollution and high relative pollution, caused by the presence of an adjacent drainage ditch. Sponge extracts were used to create antibacterial assays to test the inhibition of each sponge species at each site toward bacteria derived from the human mouth. Two of the three species, P. crassa and A. archeri, were found to inhibit bacteria, while H. helwigi showed no inhibition. Pseudoceratina crassa and Aplysina archeri taken from an area of high pollution showed greater inhibition levels than samples from areas of low pollution. Pseudoceratina crassa from both sites inhibited significantly less bacteria than A. archeri. These results suggest that sponges from high-pollution areas might be more useful than those from low-pollution areas in the production of pharmaceutical products.

This student research was retrieved from Physis: Journal of Marine Science XVI (Fall 2014)19: 38-47 from CIEE Bonaire.

The use of color is seen throughout the animal kingdom. In coral reef ecosystems, organism colorations are suggested to assist in behaviors such as camouflaging and communication among schooling fish. The long and slender Atlantic trumpetfish, Aulostomus maculatus, is suggested to take advantage of both bright and neutral color schemes on the Caribbean reefs. This species has three known colorations, or phenotypes, that all exist on the reef of the island Bonaire, Dutch Caribbean: the yellow, blueheaded, and mottled phenotypes. The mottled camouflages easily into their surroundings, the blueheaded can change the color of its head in different surroundings, and the yellow is more brightly colored than most of the substrate on the reef. This study hypothesized that there would be a strong association between bright reef fish and the hunting behaviors of the bright yellow phenotype. To observe how coloration and surroundings may influence the abundance of the yellow A. maculatus in particular, a total of 1600 m2 of abundance surveys for two phenotypes of trumpetfish and associating fish were conducted. Behavioral observations of six fish of each phenotype were conducted to examine links between coloration, surroundings, and behavior. While no links were found between coloration, surroundings and abundance, several significant links were found between coloration, surroundings, and behavior. There are a variety of factors that can affect the behavior of coral reef fishes; the data this study has collected suggests that the relationship between coloration of species and surroundings is one of these factors for the Atlantic trumpetfish

This student research was retrieved from Physis: Journal of Marine Science XVII (Spring 2015)19: 69-79 from CIEE Bonaire.

Abstract:

Background: The hydrocoral Millepora is an important framework builder that dominates shallow turbulent environments in the Indo-Pacific and the Atlantic-Caribbean. The Caribbean representatives of the genus are classified in four species - Millepora alcicornis, Millepora complanata, Millepora striata, and Millepora squarrosa - but their taxonomic boundaries are not clearly defined. We used mitochondrial gene sequences to delineate the four Millepora species and evaluated whether morphological traits and mitochondrial sequence divergence were correlated for two most common species M. alcicornis and M. complanata.

Results: Samples were collected from Puerto Rico, Guadeloupe, Curaçao, Grand Cayman, and Panama during 2006 to 2007. Diameter of dactylopores distinguished the branching and encrusting morphotypes of M. alcicornis and M. complanata, and gastropore diameter discriminated between M. alcicornis and M. complanata. High levels of haplotypic diversity (Hd = 0.94) were observed, with the most common haplotypes shared by M. alcicornis and M. complanata. Sequence divergence ranged from 0% to 3% among M. alcicornis, M. complanata, and M. striata to 25% between these three species and M. squarrosa. Bayesian analysis of cytochrome oxidase subunit I (COI) gene indicated the presence of three Caribbean taxa: M. squarrosa, M. striata, and the ‘species complex’ encompassing the morphologies displayed by M. complanata and M. alcicornis.

Conclusions: The branched M. alcicornis and encrusted M. alcicornis and M. complanata can be differentiated morphologically but not genetically. Phylogenetic analysis suggests that the Caribbean milleporids include three species - M. squarrosa, M. striata, and the species complex of M. alcicornis-M. complanata. Millepora striata is closely related to the M. alcicornis-M. complanata species complex.