Ecology

The work of this dissertation examined the secondary metabolites of several blooms of the marine cyanobacterium Lyngbya collected in Guam and Florida with an emphasis on the isolation and structure elucidation of novel biologically active compounds. The introduction in Chapter One provides a brief history of marine natural products, a description of cyanobacteria and a summary of peptides isolated from Lyngbya collected in the Caribbean. In Chapter Two, a bioassay-guided fractionation of a Floridian collection of Lyngbya polychroa led to the isolation and structural determination of the cytotoxin desacetylmicrocolin B and the known compounds microcolins A and B. The structures were established by nuclear magnetic resonance (NMR) spectroscopic analysis. All three compounds inhibited the growth of cancer cell lines HT-29 and IMR-32 at nanomolar concentrations. Microcolins A and B were found to have little activity in the ecological assay against the marine fungus Dendryphiella salina. Chapter Three describes the isolation and structure elucidation of the glycosidic, acyl proline derivative tumonoic acid J from a sample Lyngbya sp. collected in Guam. The planar structure was determined by 1D and 2D NMR spectroscopy in conjunction with high resolution-mass spectrometry (HR-MS) data. Tumonoic acid J showed moderate activity in the ecological assay against the marine fungus D. salina. In Chapter Four, NMR-guided fractionation of a Floridian sample of Lyngbya majuscula led to the isolation of two novel cyclic peptides porpoisamides A and B. The planar structures were determined by 1D and 2D NMR spectroscopy with HR-MS data. The absolute configurations of these two compounds were defined through chiral chromatographic methods and derivatization techniques.

In estuaries, like the Indian River Lagoon, mesozooplankton have a vital role in the food web by connecting trophic levels. In this study, mesozooplankton abundance and species composition were monitored weekly on the incoming and outgoing tides from September 2006 to May 2009. For the incoming tide, the mean abundance was 2298.2 mesozooplankton/m3 (+/-325.2), and for the outgoing tide the mean abundance was 1180.0 mesozooplankton/m3 (+/-153.1). The mesozooplankton abundance on the incoming tide was significantly greater than on the outgoing tide. The most abundant type of mesozooplankton was the copepod Acartia tonsa, representing 35.0% and 52.1% of the individuals on the incoming and outgoing tides respectively. Mesozooplankton abundance values were compared with environmental data obtained from the South Florida Water Management District. The strongest positive correlation was found between chlorophyll a concentrations and A. tonsa abundance, likely due to phytoplankton being the primary food source for A. tonsa.

Wading bird foraging success is influenced by many different factors. From January to March 2008, I conducted a small-scale experiment with three captive Scarlet Ibis (Eudocimus ruber) at the Palm Beach Zoo, in West Palm Beach, Florida. Prey density and the presence of conspecifics were manipulated to test for a response by ibis in terms of prey capture rate. Mixed model analysis, when one prey type was available, showed that capture rate increased significantly with prey density and decreased with the presence of conspecifics. When two prey types were available, prey density and the presence of conspecifics had no effect on the capture rates of either prey type. Selectivity analysis revealed that ibis always selected for crayfish in mixed treatments. I hypothesize that the number of prey types available in a treatment played an important role in determining how fish density and the presence of conspecifics affected ibis foraging success.

I examined the impact of the exotic, invasive plant Old World climbing fern, Lygodium microphyllum (Cav.) R. Brown, on tree island plant and ant communities in the northern Everglades. I selected 15 tree islands representing four groups: non-Lygodium islands, islands with low levels of Lygodium, islands with high levels of Lygodium, and disturbed islands impacted by people. I used a variety of diversity indices to compare plant and ant data among habitats. The ant communities studied included native and exotic species typical of south Florida. Tree island plant communities were consistent with descriptions from previous studies. Plant species richness decreased with the level of L. microphyllum in the ground and midstory layers. Abundance of native plants decreased with level of L. microphyllum in the ground, midstory, and overstory layers. Lygodium microphyllum did not affect ant communities suggesting that although it negatively impacts plant communities it can provide habitat for ants.

The role of Serrivomer beanii in bathypelagic food webs is poorly known, but abundance and biomass estimates from the 2004 G.O. Sars MAR-ECO Expedition suggest it to have a high level of importance. MAR-ECO, a Census of Marine Life field project, has allowed us to increase our knowledge of S. beanii through spatial analysis, including the congeneric species Serrivomer lanceolatoides, and trophic analysis. Serrivomer beanii abundance and biomass exhibited a decreasing trend along the northern Mid-Atlantic Ridge from north to south. In terms of size, S. beanii was found to increase as distance from the ridge decreased, suggesting a topographic aggregation strategy. The diet of S. beanii consisted of crustaceans, cephalopods, and teleosts. The trophic results of this study reveal a likely "alternative" trophic pathway in the deep mid-North Atlantic, and perhaps other, bathypelagic ecosystems: higher trophic-level predators are supported by micronektonic invertebrates as primary prey.

Sorites dominicensis is a common epiphytic foraminifera living throughout the Carribean and South Florida, and is commonly found living on turtle grass, Thalassia Testudinum. S. dominicensis plays host to algal symbionts related to those found in coral. Estimates for the numbers in these symbiotic populations are few, of limited scale, and vary widely. In this thesis we performed a large scale survey of the populations of algal symbionts living within the S. dominicensis population of Jupiter Sound. We then used this data to propose a linear model for the relationship between foraminiferal size and endosymbiont population, and to suggest explanations for the variability seen in the Jupiter Sound population.

Nearshore sabellariid worm rock reefs tracts along Florida's east cost provide developmental habitat for many juvenile green turtles.

Prior to 2000, very little was known about fish biodiversity on the New England Seamount chain. In late 2000, 115 fish species were found on Bear Seamount by the NOAA R/V "Delaware II." Woods Hole Oceanographic Institution conducted two cruises to explore the New England Seamount chain in 2003. This study assessed fish species throughout Alvin submersible dives during these 2003 cruises. Digital video footage was converted to still photographs and video clips using the Macintosh movie program iMovie. Fishes were identified to the lowest possible taxonomic level using keys and literature. The habitat, depth and behavior of observed fishes were compared to the literature available. Geographical distributions of the species were considered. I assessed substrate preference by building a chart that reflects the different sediment regimes that fishes were found on. In all I identified 317 individuals representing 33 different taxa, including two species with new habitat range information Neocyttus helgae and Lepidion sp.

Freshwater marshes are a harsh wetland ecosystem classified by seasonal water level fluctuation. Dry down periods are common in some marshes, making life difficult for fish and other aquatic organisms. The goal of this study was to compile an updated species list of fishes inhabiting the freshwater marsh system within Savannas Preserve State Park. Twenty-three fish species were collected between August 2005 and May 2007. This survey, along with past collections, and the current species list in the park's management plan were used to make a new proposed species list. Three species of nonnative fishes were observed during the study, the first report of exotic fishes in the park. It is believed that abnormally high water levels for an extended period may have allowed the water in neighboring canals to connect to the marsh system and, as a result, new species were able become introduced in the park.