Analysis of heterotrophic microplankton in an upwelling area

Abstract

The role played by heterotrophic microplankton in the synthesis and flux of organic matter was studied in the Punta San Juan Coastal upwelling region off Peru in April and May 1977 . The data from a drogue study show that the main component of the planktonic community in the freshly upwelled water is the microheterotroph component . The biomass of bacteria (49 mg C/m') in the newly upwelled water exceeded by two orders of magnitude the biomass of phytoplankton . Total respiration of the microheterotrophs (335 g C/m 2 /day) exceeded by three-fold the pnmary production, indicating that the heterotrophic respiration was dependent on the content of organic matter preexisting in the upwelling waters . In the upwelling at Punta San Juan the biomass of protozoa was I g/ m3 (wet weight) at the depth of the maximum concentration ; this concentration is the highest ever observed in sea water . During transects on a section normal to the coastline an abundant population of dinoflagellates (5 to 40 x Io 3/1) of the genera Gymnodinium and Prorocentrum were found in anoxic waters at 50 to too m. Strong red tide water coloration was observed as a result of a bloom of the autotrophic ciliate Mesodinium rubrum; the biomass of the ciliate at the surface in calm weather reached 50 to 70 g/ m3 (wet weight) and the cell density was 2 to 4 x 106/1 .

The role of heterotrophic microflagellates in plankton communities

“…Maximum abundances of pico-and nanoplankton in Lake Ontario exceeded maximum abundances of these populations in the marine environments examined in this study, but are in agreement with population densities observed in eutrophic marine environments (Vinogradov et al, 1976;Tumantseva & Sorokin, 1977;Sorokin & Kogelschatz, 1979;Tumantseva, 1981 (Alldredge & Cox, 1982;Knauer et al, 1982;Prezelin & Alldredge, 1983) and heterotrophy (Silver et al, 1978;Trent et al, 1978;Caron et al, 1982) relative to equal volumes of the surrounding water. They have been shown to be sites of nutrient enrichment (Shanks & Trent, 1979) and have been suggested as a food source for epipelagic (Alldredge,.…”

“…This literature indicates relatively large standing stocks of Hnano in the ocean (Vinogradov et al, 1976;Tumantseva & Sorokin, 1977;Sorokin & Kogelschatz, 1979;Silver et al, 1980;Tumantseva, 1981Davis et al, submitted). A similar situation appears to exist -13-in freshwater environments although very few data are available (Appendix V;…”

Stable isotope geochemistry of nitrogen in marine particulates

“…It is important to note that the anchovy bi omass is very large, larger than that of the zooplankton (Whitledge and Packard, 1971). Large bacterial numbers have also been reported by Sorokin and Kogel schatz (1979) and Watson (1979).…”

Abundance and dynamics of microplankton in the central tropical Indian Ocean

“…All data on microbial biomass and production presented in the tables are units of wet biomass containing 10 % carbon. Rate of bacterioplankton respiration was calculated from data on microbial production, accepting that (1) carbon contents in the microbial biomass are equal to 10 % (Troitsky & Sorokin 1967); (2) efficiency coefficient K, of microbial production (use of consumed food for growth) is equal to 0.32 in natural sea water bacterioplankton (Sorokin & Kogelschatz 1979); (3) the respiration coefficient is equal to 1. Then, microbial respiration (M) will be equal to:…”