Seasonal patterns of growth and composition of phytoplankton in the lower Chesapeake Bay and vicinity

Abstract

A twenty-three month study of lower Chesapeake Bay phytoplankton was made from February 1982 to December 1983. The major seasonal growth periods were dominated by a diatomaceous flora and a pico-nanoplankton complex composed mainly of cyanobacteria, chlorophytes and other cells <5μm in size. There was a pattern of multiple pulses throughout the year. However, the trend for maximum development occurred during the winter-spring and fall periods. The dominant diatoms were Skeletonema costatum, Leptocylindrus danicus, and Asterionella glacialis. Seasonal comparisons were made to earlier phytoplankton composition studies in the Bay. Over the past 60 years there has been a change in phytoplankton assemblages and concentrations in the Bay. Skeletonema costatum has remained a dominant species, but a more abundant and broader base of small sized, chainforming diatoms have become established. In addition, high concentrations of the pico-nanoplankton, chrysophyceans and cryptophyceans were abundant.