Plankton dynamics along a 180 km reach of the St Lawrence River from its headwaters in Lake Ontario.
Автор: M. Twiss, C. Ulrich, S. A. Kring, J. Harold, M. R. Williams
St. Lawrence River–Great Lakes Ecosystems: An Ecological Overview
Hydrobiologica, Jan. 2010
We test the hypothesis that phytoplanktonbiomass decrease upon entry into the St. LawrenceRiver from headwaters in Lake Ontario is attributableto a range of causal factors including, decreasedphotosynthetic fitness due to turbulence, cell loss dueto increased flocculation and subsequent sedimentation,decreases in nutrients, and loss due to grazing.In order to test this, changes in phytoplankton andcrustacean zooplankton concentrations were examinedduring four transects along the river, from 8 kmoffshore in Lake Ontario to the hydroelectric powerdam 180 km downstream. Both phytoplankton biomass,measured as chlorophyll-a, and zooplanktondecreased markedly upon entry of lake water into theriver. Phytoplankton community composition andsize changed little over the river reach and tended toreflect that in Lake Ontario.
