Primary productivity, phytoplankton populations and nutrient bioassays in China Lake, Maine, U. S. A.

Summary

Phytoplankton samplings and in situ nutrient-enrichment bioassays were conducted from July, 1972 to August, 1973. Correlations of cell numbers and cell volume with other community properties differed. Responses to nutrient additions in four-hour ¹⁴C bioassays and in one to three week chlorophyll bioassays both differed markedly by season and were maximal in early summer for all nutrients tested. The trace elements Fe, Mn, and Mo elicited responses throughout the year, while the major elements, P, N, and Si elicited responses primarily during periods of high standing crop, community constancy, and favorable light and temperature. Principal component analyses of the phytoplankton data depicted seasonal changes in community composition and together with the bioassay results revealed a complex, shifting spectrum of nutrient effects on the phytoplankton assemblages.

This research was supported by grant A-026-ME from the U. S. Office of Water Resources Research.