Cyanobacterial, Microcoleus lyngbyaceus, and drift eucaryotic macroalgal assemblages in inshore seagrass habitats in southwest Puerto Rico

Coastal eutrophication and subsequent cyanobacterial and algal blooms have been occurring for the last several years in Southwest Puerto Rico. Large mats of the filamentous cyanobacteria Microcoleus lyngbyaceus (Kützing) Crouan have been observed to cover and are associated with the disappearance of inshore seagrasses.; The aim of this study was to document the status of Microcoleus populations as well as other unattached or drift algal blooms at inshore shallow-water habitats of La Parguera, Puerto Rico. Algal biomass and percent cover as well as seasonal changes were documented. Biomass of Microcoleus lyngbyaceus ranged from 0 to 634 g/m2 during the study period. Percent cover ranged from 0% up to nearly 100% in some areas. It was determined that drift populations of eukaryotic and cyanobacterial algae are abundant in nearshore habitats in Southwest Puerto Rico, and blooms of Microcoleus lyngbyaceus are apparently detrimental to Thalassia testudinum.