Marine Biodiversity in the Caribbean: Regional Estimates and Distribution Patterns

This paper provides an analysis of the distribution patterns of marine biodiversity and summarizes the major activities of the Census of Marine Life program in the Caribbean region. The coastal Caribbean region is a large marine ecosystem (LME) characterized by coral reefs, mangroves, and seagrasses, but including other environments, such as sandy beaches and rocky shores. These tropical ecosystems incorporate a high diversity of associated flora and fauna, and the nations that border the Caribbean collectively encompass a major global marine biodiversity hot spot. We analyze the state of knowledge of marine biodiversity based on the geographic distribution of georeferenced species records and regional taxonomic lists. A total of 12,046 marine species are reported in this paper for the Caribbean region. These include representatives from 31 animal phyla, two plant phyla, one group of Chromista, and three groups of Protoctista. Sampling effort has been greatest in shallow, nearshore waters, where there is relatively good coverage of species records; offshore and deep environments have been less studied. Additionally, we found that the currently accepted classification of marine ecoregions of the Caribbean did not apply for the benthic distributions of five relatively well known taxonomic groups. Coastal species richness tends to concentrate along the Antillean arc (Cuba to the southernmost Antilles) and the northern coast of South America (Venezuela – Colombia), while no pattern can be observed in the deep sea with the available data. Several factors make it impossible to determine the extent to which these distribution patterns accurately reflect the true situation for marine biodiversity in general: (1) highly localized concentrations of collecting effort and a lack of collecting in many areas and ecosystems, (2) high variability among collecting methods, (3) limited taxonomic expertise for many groups, and (4) differing levels of activity in the study of different taxa

New Evidence for the West Florida Shelf Plume

The occurrence of an episodic chlorophyll plume detected on the West Florida Shelf between 1979 and 1986 was confirmed in March 1995 with shipboard data and in March 1998 with new ocean color data from the SeaWiFS sensor. New evidence is presented to support the hypothesis that diatom blooms off Apalachicola Bay are the precursor of the seasonal West Florida Shelf plume, and that the nutrient requirements for such blooms, especially silicate, can be supported by river discharge. The observations indicate that the impact of rivers is maximal over the middle shelf and decreases over the outer shelf. Salinity and discharge measurements support the concept that the Apalachicola River had a major impact at distances exceeding 100 km from the coast and that it plays an important role in the formation of offshore blooms. Preliminary analyses suggest that successional processes lead to cryptophytes dominating in the offshore blooms

An Episodic Chlorophyll Plume on the West Florida Shelf

The episodic formation of an extensive pigment plume on the West Florida Shelf was detected using historical Coastal Zone Color Scanner (CZCS) data collected between 1979 and 1986. The phenomenon is confirmed by in situ observations made in March 1992. The plume occurs mainly during spring, when high pigment concentrations persist 1-6 weeks in a pattern which extends \u3e250 km southward along the shelf. In general, the shelf and continental slope had low pigment concentrations during summer and high pigment concentrations during spring. The information currently available is insufficient to determine the cause of the plume with certainty. Plume formation may be associated with one or a combination of the following processes: (1) discharge from small, local rivers along the NW Florida coast; (2) seasonal changes in steric height differences between the shelf and deep Gulf of Mexico waters; (3) circulation of water associated with the Loop Current and upwelling in the DeSoto Canyon; and (4) discharge from the Mississippi and Mobile Rivers. Copyrigh

On the Dispersal of Riverine Colored Dissolved Organic Matter Over the West Florida Shelf

We investigated the optical properties of surface water in areas of the West Florida Shelf influenced by riverine discharge and by the occurrence of a phytoplankton plume. Results of absorption and fluorescence spectroscopy analyses and determination of dissolved organic carbon (DOC) concentration showed that the injection of riverine colored dissolved organic matter (CDOM) strongly affected the optical properties and DOC concentrations over the shelf. Riverborne nutrients contributed to an increase in primary productivity. However, during the study period, the increase in primary productivity did not result in the production of significant amounts of CDOM. Fluorescence spectroscopy results showed that optical properties of riverine CDOM were lost close to the mouth of the rivers. A simple mathematical model describing mixing between riverine and marine end-members demonstrated that most of the observed changes in optical properties of CDOM along salinity gradients can be explained by mixing. Laboratory mixing experiments between riverine water and seawater indicated that flocculation of organic matter during estuarine mixing did not affect the optical properties of CDOM

Late Holocene sea-level rise in Tampa Bay: Integrated reconstruction using biomarkers, pollen, organic-walled dinoflagellate cysts, and diatoms

A suite of organic geochemical, micropaleontological and palynological proxies was applied to sediments from Southwest Florida, to study the Holocene environmental changes associated with sea-level rise. Sediments were recovered from Hillsborough Bay, part of Tampa Bay, and studied using biomarkers, pollen, organic-walled dinoflagellate cysts and diatoms. Analyses show that the site flooded around 7.5 ka as a consequence of Holocene transgression, progressively turning a fresh/brackish marl-marsh into a shallow, restricted marine environment. Immediately after the marine transgression started, limited water circulation and high amounts of runoff caused stratification of the water column. A shift in dinocysts and diatom assemblages to more marine species, increasing concentrations of marine biomarkers and a shift in the Diol Index indicate increasing salinity between 7.5 ka and the present, which is likely a consequence of progressing sea-level rise. Reconstructed sea surface temperatures for the past 4 kyrs are between 25 and 26 ° C, and indicate stable temperatures during the Late Holocene. A sharp increase in sedimentation rate in the top ∼50 cm of the core is attributed to human impact. The results are in agreement with parallel studies from the area, but this study further refines the environmental reconstructions having the advantage of simultaneously investigating changes in the terrestrial and marine environment. © 2009 Elsevier Ltd