Population dynamics and production of cladoceran zooplankton in the highly eutrophic Lake Kasumigaura

Abstract

The growth rate, birth rate, death rate and production of the cladocera of Lake Kasumigaura were studied. Standing crop of zooplankton seemed to be governed by predation rather than food. Maximum productivity of cladocerans was observed in late August and early September. There were differences in production between sampling stations. The highest production was recorded in the most eutrophic basin, where heavy water blooms of Microcystis aeruginosa occurred. Maximum secondary production coincided with maximum primary production, which was mainly due to M. aeruginosa. Cladocerans probably utilize decomposed or decomposing Microcystis cells and bacteria in summer. Estimates of annual production of cladocerans varied from 4.2 to 13.1 g dry wt + m-3, and annual P:B ratios ranged from 36 to 108. The production of cladocerans in Takahamairi Bay was 2.7% of gross primary production.

Development of tolerance against toxic Microcystis aeruginosa in three cladocerans and the ecological implications

“…Eutrophication has resulted in a wide increase of cyanobacterial blooms (Shapiro, 1972;Paerl et al, 2001;Havens et al, 2003), often leading to changes in the structure of zooplankton communities (Nanazato and Yasuno, 1985;Trabeau et al, 2004). Microcystis is one of the most common and most studied bloom-forming cyanobacteria and a well-known producer of the hepatotoxic microcystins (Sivonen, 1999;Jungmann, 1992).…”

Characteristics of Biomass and Production of Cladoceran Zooplankton in Lake Kasumigaura

“…1, 3, 7 and 9 presented in the figure are the equivalent of Stas. A, B, C, and D in our previous report (HANAZATO and YASUNO, 1985a), respectively.…”

“…In Japan, however, there are few studies on it. The zooplankton production had not been studied comprehensively in Japanese lakes before the present authors' work (HANAZATO and YASUNO, 1985a), which clarified the characteristics of the population dynamics, biomass and production of the dominant zooplankton group, Cladocera, in Lake Kasumigaura in 1983. In the present paper, the studies following the previous report are presented, and the variation from year to year of the species composition, biomass and production are clarified.…”

“…To estimate the cladoceran biomass, we determined equations of body length-weight relationships for four dominant species (Diaphanosoma brachyurum, Bosmina f atalis, Bosmina longirostris, Moina micrura), which were shown in our previous report (HANAZATO and YASUNO, 1985a). The weights of Daphnia ambigua, Chydorus sphaericus and Ceriodaphnia cornuta (= C. rigaudi) were calculated using the equations for D. ambigua, C.…”

“…Cladoceran biomass Figure 4 shows the seasonal changes in the integrated biomass of the seven cladoceran species during 1983 -1985. The data in 1983 in this figure were cited from HANAZATO and YASUNO (1985a). In…”