Variacion espacial y temporal del fitoplancton en la Bahia de Mayaguez, Puerto Rico.

摘要

Mayaguez Bay is an area off western Puerto Rico affected by effluents of domestic waste treatment plants and the three major rivers flowing into the region. In either case, anthropogenic factors are seen as contributing elements influencing its primary production. This study represents an effort to study the diversity, abundance, and temporal and spatial variations of the phytoplankton in Mayaguez Bay.; Phytoplankton samples and physical-chemical parameters (temperature, salinity, nutrients, and chlorophyll-a), were collected at four coastal and two oceanic stations during the rainy season (2005) and the dry season (2006). Phytoplankton was identified using scaninnig electron microscopy techniques and Nomarsky microscopy; cell counts were done under a regular compound microscope in a Neubauer chamber.; The highest abundance (4685 cells/liter) was observed during the dry season in April, 2006. The phytoplankton composition throughout the study was made up principally by diatoms and dinoflagellates. The chlorophycea, cocolithophorida, and cyanophycea were infrequent. The most abundant genera were Asterionella, Guinardia, Skeletonema, Chaetoceros, Cylindrotheca, Alexandrium, Rhizosolenia, Ceratium, Gonyaulax, and Protoperidinium .; Surface temperature and salinity data showed a sharp influence on the succession of the phytoplankton community. The statistical analysis indicated that population of phytoplankton and the concentration of chlorophyll- a were significantly different in space and time. However, independently of the abundance, the highest concentration of chlorophyll-a was observed during the rainy season. High densities of phytoplankton were found associated with high concentration of nitrates.; In general, Mayaguez Bay can be classified as a complex estuarine system integrating nearshore and oceanic species. Continuous changes in nutrients due to river discharges influence the species and also maintain their diversity.