SPATIAL AND TEMPORAL DISTRIBUTION OF PHYTOPLANKTON IN THE CHESTER RIVER, MARYLAND

Abstract

Phytoplankton samples were collected at six stations in the Chester River, Maryland, during eight monthly surveys. Identification and enumeration of phytoplankton species/genera revealed seasonal and station specific patterns. Diatoms dominated the river during the winter and early spring; dinoflagellates and green algae dominated during the summer, and diatoms began to dominate again in the late summer and fall. Seasonal peaks in cell numbers occurred in a pattern that was somewhat different than the patterns seen in other subestuaries of the Chesapeake Bay. The largest peak occurred in the winter and a smaller one occurred in late summer. Seventy-eight different species, representing seven classes, were identified. Generalized sketches of these individuals are included in an appendix. Many other species of nannoplankton (cells < 10 um) were counted but not identified. Nannoplankton percentages ranged from 0.4 to 79 percent. Highest percentages for the less saline stations (B, 13, and 22) occurred during winter and early spring. Highest percentages for the more saline stations (34, 48, and 51) occurred in July. Total cell counts for the Chester River were lower than expected since evidence indicates that nutrient levels have increased over the past decade. Secchi depths were low (0.2 meters to 0.9 meters) especially for the stations near the head of the river. This suggests a limiting factor for phytoplankton growth in the form of light limitation due to turbidity.