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Medientyp:
E-Artikel
Titel:
Biomass and Productivity of Three Phytoplankton Size Classes in San Francisco Bay
Beteiligte:
Cole, Brian E.;
Cloern, James E.;
Alpine, Andrea E.
Erschienen:
Estuarine Research Federation, 1986
Erschienen in:Estuaries
Sprache:
Englisch
ISSN:
0160-8347
Entstehung:
Anmerkungen:
Beschreibung:
<p> Primary productivity of three size classes of phytoplankton (<5 μm, 5-22 μm, >22 μm) was measured monthly at six sites within San Francisco Bay throughout 1980. These sites in the three principal embayments were chosen to represent a range of environments, phytoplankton communities, and seasonal cycles in the estuary. Temporal variations in productivity for each size class generally followed the seasonality of the corresponding fraction of phytoplankton biomass. The 5-22 μm size class accounted for 40 to 50% of the annual production in each embayment, but production by phytoplankton >22 μm ranged from 26% in the southern reach to 54% of total phytoplankton production in the landward embayment of the northern reach. A productivity index is derived that predicts daily productivity for each size class as a function of ambient irradiance and integrated chlorophyll a in the photic zone. For the whole phytoplankton community and for each size class, this index was constant and estimated as ≃ 0.76 g C m<sup>-2</sup> ( g chlorophyll a Einstein)<sup>-1</sup>. The annual means of maximum carbon assimilation numbers were usually similar for the three size classes. Spatial and temporal variations in size-fractionated productivity are shown to be primarily due to differences in biomass rather than size-dependent carbon assimilation rates. </p>