Offshore distribution patterns of the cyanobacterium Trichodesmium erythraeum ehrenberg and associated phyto- and bacterioplankton in the southern atlantic coast (Paraná, Brazil)

Abstract

Studies were carried out on Thrichodesmium erythraeum occurring on the inner shelf in the state of Paraná, Brazil. Temperature, salinity, rainfall, wind velocity, total bacteria, bacterial biomass, chlorophyll-a, phytoplankton, Anabaena sp., Merismopedia sp. and T. erythraeum densities were measured in surface water. Centric and pennate diatoms, Anabaena sp. and Merismopedia sp. were most abundant at 15 m isobath, while dinoflagellate abundance was relatively constant among stations. Similarly, total bacterial densities were relatively homogeneous throughout the sampling area, suggesting that blooms of T. erythraeum were not yet in the senescent phase. Results showed that T. erythraeum was capable of surviving in relatively inhospitable environmental conditions, due to its ability to fix nitrogen and to photosynthesis at high light intensities.