Coral reef ecology

Nitrogen (N) has traditionally been regarded as the primary limiting nutrient to algal growth in marine coastal waters, but recent studies suggest that phosphorus (P) can be limiting in carbonate-rich environments. To better understand the importance of P. alkaline phosphatase activity (APA) was measured in reef macroalgae in seven counties of south Florida ; several significant trends emerged : 1) APA decreased geographically from the highest values in Dada>Monroe>Palm Beach>St. Lucie>Broward>Martin>Lee counties 2) APA varied temporally with increasing nutrient-rich runoff in the wet season 3) APA varied due to taxonomic division Phaeophyta>Rhodophyta>Chlorophyta 4) Nutrient enrichment experiments demonstrated that increased N-enrichment enhanced P-limitation while increased P decreased P-limitation. These results suggest that high APA observed in carbonate-rich waters of Dade County and low APA in Broward County resulted from high nutrient inputs associated with anthropogenic nutrient pollution.

Briareum asbestinum, a soft coral, is a rich source of diterpenoid natural products. The secondary metabolites of B. asbestinum fall into four classes : asbestinins, briarellins, briareolate esters, and briaranes. Briareolate esters have been shown to possess biological activity and were previously only reported from Tobago. Our group recently isolated briareolate esters from a specimen collected off the coast of Boca Raton, Florida. To determine whether location has an impact on the chemistry produced by the organism, a method to discern between chemotypes was sought. Several techniques including thin layer chromatography (TLC), high performance liquid chromatography (HPLC), nuclear magnetic resonance (NMR), and sclerite analysis were employed, with NMR being the most successful method. By utilizing both 1H and COSY NMR experiments, it is possible to differentiate between the chemotypes of B. asbestinum. Application of this method allowed analysis of chemical variability with respect to location.

A benthic environments classification system is devised from digital interpretations of multi-spectral IKONOS satellite imagery for 1,360 km2 of the carbonate platform and presented in a comprehensive digitized map. The classification scheme is designed as a 7th order hierarchical structure that integrates 5 Physiographic Realms, 24 Morphodynamic Zones, 11 Geoforms, 39 Landforms, 6 dominant surface sediment types, 9 dominant biological covers and 3 densities of biological covers for the description of benthic environments. Digital analysis of the high-resolution (4 m) IKONOS imagery employed ESRI's ArcMap to manually digitize 412 mapping units at a scale of 1:6,000 differentiated by spectral reflectance, color tones, and textures of seafloor topologies. The context of each morphodynamic zone is characterized by the content and areal distribution (in km2) of geomorphic forms and biological covers. Over 58% of the mapping area is occupied by sediment flats, and seagrasses are colonized in almost 80% of the topologies.

The Florida Reef Tract in Southeast Florida is made up of hard-bottom formations. The shape and size of the tract is constantly changing. One major factor contributing to these changes is the movement of sand. This is influenced by location-based, human-induced, and natural factors. These shifting sands cover or uncover reef structure. Images of the Florida Reef Tract in Palm Beach County were analyzed by the Department of Geosciences at Florida Atlantic University, using a partially automated method of mapping. There are notable changes in reef structure throughout the years 2004-2006, in which many major storm events occurred in the region. A time series analysis was conducted throughout these years. Losses and gains of reef structure were quantified and compared throughout the county as a whole, in beach renourishment project areas, and inlet intervals. Trends suggest that the major storms of 2004-2006 may have had effects on the reef tract.

Much of the world's oceans lie below a depth of 200 meters, but very little is known about the creatures that inhabit these deep-sea environments. The deep-sea fish family Melamphaidae (Stephanoberyciformes) is one such example of an understudied group of fishes. Samples from the MAR-ECO (www.mar-eco.no) project represent one of the largest melamphaid collections, providing an ideal opportunity to gain information on this important, but understudied, family of fishes. The key to the family presented here is the first updated, comprehensive key since those produced by Ebeling and Weed (1963) and Keene (1987). Samples from the 2004 MAR-ECO cruise and the U.S. National Museum of Natural History provided an opportunity to review two possible new species, the Scopelogadus mizolepis subspecies, and a Poromitra crassiceps species complex. Results show that Scopeloberyx americanus and Melamphaes indicoides are new species, while the two subspecies of Scopelogadus mizolepis are most likely o nly one species and the Poromitra crassiceps complex is actually several different species of Poromitra. Data collected from the MAR-ECO cruise provided an opportunity to study the distribution, reproductive characteristics and trophic ecology of the family Melamphaidae along the Mid-Atlantic Ridge (MAR). Cluster analysis showed that there are five distinct groups of melamphaid fishes along the MAR. This analysis also supported the initial observation that the melamphaid assemblage changes between the northern and southern edges of an anti-cyclonic anomaly that could be indicative of a warm-core ring. Analysis of the reproductive characteristics of the melamphaid assemblage revealed that many of the female fishes have a high gonadosomatic index (GSI) consistent with values found for other species of deep-sea fishes during their spawning seasons.

The sea anemone Bartholomea annulata, is an ecologically important member of Caribbean coral reefs. This anemone serves as symbiotic host to crustacean associates, some of which may control parasite loads by "cleaning" reef fishes. Associates may gain protection from predation by dwelling with anemones. B. annulata was the most abundant anemone documented on three reefs, with 52% host to crustacean symbionts. Of those occupied by multi-species groups, 92% included Alpheus armatus shrimp. A. armatus is an important anemone associate providing protection to the anemone from predators such as Hermodice carunculata, in laboratory and field trials. H. carunculata can completely devour or severely damage prey anemones. Here I show that anemones hosting symbiotic alpheid shrimp are extremely less likely to sustain damage by predators than solitary anemones. The role of protector may be reciprocally provided by anemone and decapod associates.

Coral reefs worldwide are threatened by many environmental disturbances including harmful algal blooms (HABs) which have been increasing on Florida coasts over the past decade. Research has mainly focused on HAB identification, percent cover and other effects on the benthos but the relationship of HABs with upper trophic levels has received less attention. To study this relationship, a two-year investigation on a 10-m deep reef off of Hallandale Beach, was conducted. Stationary fish census coupled with benthic transect videos were conducted quarterly between April 2005-July 2007. A significant correlation between Lyngbya sp. blooms and alterations in fish assemblages was observed. Lyngbya had a negative interaction with fish species and abundance; additionally, HAB sample periods were significantly different from low algal abundance periods. Blooms of Dictyota sp. had no measurable relationship with the fish assemblage indicating HABs may have variable impacts on fishes depending on family, species and chemistry of the algae.

Coral reefs harbor ~1-9 million species, including 30% of all marine fish species. Reef health worldwide is declining due to many factors: e.g. pollution, sedimentation, dynamite fishing, and global warming. Working with the Planetary Coral Reef Foundation and the crew aboard the R/V Heraclitus, I examined coral health and fish diversity in the Solomon Islands, Melanesia. In 2006, I surveyed coral and fish on Sagharughombe reef, Solomon Islands using SCUBA and compared the results with surveys done in 2000 and 2002. Coral surveys indicated a significant decline in health over the six-year period. Fish surveys found no clear trend in species abundances and species richness, but a significant decline in species diversity over the years. The decline in coral health we observed may have contributed to diminished fish diversity. To protect marine biodiversity, coral reefs must be better protected and declines in coral health must be halted.