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281.
J.E. Toro 《Estuarine, Coastal and Shelf Science》1985,21(4):461-469
Phytoplankton species and abundance were studied in the Quempillen River Estuary, from August 1979 to July 1980 in addition to some important environmental factors: salinity, temperature and dissolved oxygen. In order to determine the seasonal variations in cell density and biomass of the phytoplankton in this brackish aquatic environment, phytoplankton data obtained by the Uthermöhl (1958) technique were analysed.A total of 109 phytoplankton species were identified within the samples. Throughout the year there were two periods of population maxima, September and May, and one period of high biomass, February. The phytoflagellates were always present but only dominated the flora when diatoms were extremely reduced, especially during low tide periods. 相似文献
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The abundance of a scyphomedusae, Aurelia aurita and Chrysaora melanaster, and a ctenophore, Bolinopsis mikado, in Tokyo Bay was investigated from 1995 to 1997. Aurelia aurita appeared throughout the year with a peak in abundance occurring from spring to summer. The average abundance and biomass
during this period for the three successive years was 4.8, 43.8 and 3.2 ind. m−2, and 1.02, 10.0 and 0.42 gC m−2, respectively. The values in 1995 and 1997 were comparable with those previously reported for A. aurita abundance from 1990 to 1992. Values were very high in 1996, but the size composition of the bell diameter did not differ
from other years, which suggested the absence of food limitation for A. aurita in 1996. C. melanaster was scarce over the survey period (<1.0 ind. m−2) while Bolinopsis mikado was more abundant during September to December, with maximum values of 172 ind. m−2 and 0.33 gC m−2 observed in December 1997. The weight-specific clearance rate for A. aurita on zooplankton (mainly copepods and their nauplii) was 0.16 ± 0.05 lgWW−1 h−1 (n = 13). Population clearance rate peaked from spring to summer, with average levels of 14.2%, 162% and 5.0% day−1 obtained from spring to summer for respective years. Population clearance rates for B. mikado, calculated based on minimum carbon requirements, was 7.1% day−1 in December 1997. Consequently, the trophic role of gelatinous zooplankton as predators in Tokyo Bay is important all the
year round, considering the high impact of A. aurita from spring to summer and B. mikado from autumn to winter. 相似文献
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