Aquatic ecology

The Deepwater Horizon Oil Spill had widespread impacts that were seen across the surface of the ocean, deep-sea, and seafloor. To assess damages, NOAA and GoMRI established the Offshore Nekton Sampling and Analysis Program (ONSAP) and the Deep Pelagic Nekton Dynamics of the Gulf of Mexico (DEEPEND) projects. This response effort would create a vast dataset and collection of samples to aid in understanding the deep-sea of the northern Gulf of Mexico.
Genus Melamphaes (Family Melamphaidae), are a group of minimally characterized and understudied fish. This thesis will assess vertical ecology and migratory patterns, variations in specimen size and sampling gear, and introduce species that are newly identified to inhabit the area. The findings suggest that majority of Melamphaes participate in diel vertical migration and sampling equipment has significant impacts on specimen size. Four unreported species of Melamphaes have now been documented in this region, increasing previously reported diversity.

Roughly 92% of the total volume of Earth's oceans is considered deep sea.
The eel species, Nemichthys scolopaceus, inhabits these waters, and little is known of
its diet, its place within pelagic food webs, and its overall ecological impact. In this
study we quantitatively estimate the abundance, feeding and predation impact of this
key predator. Specimens were collected in 2004 along Georges Bank as part of the
Census of Marine Life Gulf of Maine project. Gut contents were analyzed, revealing
thirteen prey types, primarily euphausiids and decapod crustaceans. Other potential
prey (i.e. fishes) were absent from the diet, suggesting a fairly selective feeding
preference. Of the 85 fish species collected, N scolopaceus ranked second in
abundance and first in total fish biomass. Therefore, this species is not only a large
biomass contributor, but perhaps cycles a great deal of macrocrustacean carbon
through deep-pelagic fishes in this, and likely other, ecosystems.

Oyster reefs are biodiverse communities that provide many ecological and commercial benefits. However, oyster reefs have declined around the world from human activities. Oyster reef restoration programs have begun to limit some of the decline, but the need for determining the success of a program has been problematic. Passive acoustic techniques can use naturally occurring sounds produced by organisms to assess biodiversity. Passive acoustics was utilized to compare the sounds in natural and restored oyster reefs, with special attention on snapping shrimp (Alpheus spp.) snap sounds, in the St. Lucie Estuary, Florida over a one year period. Season, estuary region, habitat and day period had an effect on sound production. Passive acoustic monitoring of snapping shrimp sound production may be a useful non-destructive technique for monitoring the progress of oyster reef restoration projects once further correlations are established between environmental effects and sound production.

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.