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Nitrogenous nutrition of the plankton in the Chesapeake Bay. 1. Nutrient availability and phytoplankton preferences
Author(s) -
McCarthy James J.,
Taylor W. Rowland,
Taft Jay L.
Publication year - 1977
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1977.22.6.0996
Subject(s) - phytoplankton , nutrient , plankton , chesapeake bay , urea , bay , environmental chemistry , environmental science , zoology , oceanography , chemistry , biology , ecology , estuary , biochemistry , geology
Eight stations in the main body of Chesapeake Bay and one on the continental shelf were sampled seven times over a period of 13 months to investigate the nitrogenous nutrition of the phytoplankton. The rates at which the phytoplankton were utilizing NO 3 − , NO 2 − , NH 4 + , and urea N were determined. The data demonstrate that for a large portion of the year there is inadequate N nutrient available to permit a single doubling of the particulate N. Over temperatures from 4°–28°C and salinities from 2–32‰, there was a universally high phytoplankton preference for NH 4 + and urea N over NO 3 − and NO 2 − . A relative preference index indicated that NH 4 + concentrations in excess of 0.5–1.0 µ g‐atom N liter −1 almost totally suppressed NO 3 − utilization. Urea N was used after NH 4 + in order of preference, and when the sum of available NH 4 + and urea N was insufficient to meet the phytoplankton N nutrient demand, NO 3 − was used. When the sum of all available N nutrients was less than that required to satiate the phytoplankton demand, NH 4 + , urea N, NO 3 − , and NO 2 − were all utilized at rates proportional to their availability. For the midbay region in October 1973, NO 2 − was the dominant N nutrient present both in the water and in the diet of the phytoplankton.