Spatial and temporal distributions of zooplankton in Tampa Bay, Florida, including observations during a HAB event

摘要

This study describes spatial and temporal distributions of the zooplankton community in Tampa Bay, including their distributions during a bloom of the toxic dinoflagellate Pyrodinium bahamense. Three sites in the bay were sampled 30 times from April 2002 to April 2003. Abundances of holoplankton (copepod nauplii included), meroplankton and microzooplankton were determined using light microscopy. This is the first observation of microzooplankton in Tampa Bay. Phytoplankton composition, temperature, salinity, Secchi depth, total nitrogen, total phosphorus and chlorophyll a were also determined. Generally, the inner bay had higher zooplankton abundances than the mid- and outer regions of the bay. The dominant holoplankton species were copepod nauplii, Oithona colcarva, Acartia tonsa and the larveacean Oikopleura dioica. Bivalve larvae were the most abundant meroplanktonic taxa and tintinnids the most abundant microzooplankton. A major bloom of P. bahamense was observed in the inner bay during the summer. During the bloom, numerical abundances of O. colcarva and A. tonsa declined, while abundances of O. dioica mimicked the pattern of P. bahamense abundance. Picoplankton and diatom concentrations also decreased during the bloom. Spatial patterns and temporal trends in zooplankton distribution suggest that regional differences in water residence times, salinity regimes and grazing pressures are important driving factors in the composition and abundance of zooplankton in Tampa Bay. The results of the study are discussed within the context of historical observation of the zooplankton community.