Bloom and toxin producing algae in Virginia tidal rivers

Abstract

A diverse representation of algal species are common bloom producers in the tidal waters of Virginia tributaries that enter Chesapeake Bay. In the lower more saline regions of these rivers dinoflagellates are the major bloom producers. Their increased abundance and occurrence generally follows the spring diatom bloom and continues into summer and autumn. These common bloom producers include the diatoms Skeletonema potamos, Skeletonema costatum, Cerataulina pelagica, and Leptocylindrus minimus, plus the dinoflagellates Akashiwo sanguinea, Cochlodinium polykrikoides, Heterocapsa rotundata, Heterocapsa triquetra, Prorocentrum minimum, and Scrippsiella trochoidea. Of these dinoflagellates the major bloom producer in regions of the lower York and James rivers is Cochlodinium polykrikoides. Also occurring in these downstream waters are the recognized toxin producers Alexandrium monilatum, Chattonella subsalsa, and Karlodinium veneficum. In contrast, the tidal freshwater regions of these rivers more commonly would produce cyanobacteria blooms, including those by Microcystis aeruginosa.