Seasonality, population dynamics and production of planktonic rotifers in Lough Neagh, Northern Ireland

Abstract

The abundances, population dynamics and production of the rotifer community of Lough Neagh were examined for a three year period. Keratella cochlearis was the most abundant species accounting for over 40% of biomass followed by Polyarthra dolichoptera and Notholca acuminata. The mean standing crop for the rotiferan zooplankton increased in successive years (41, 51, 75 mg dwt m-2) as did production (1037, 1322, 1417 mg dwt m-2 y-'). The seasonal pattern of biomass expression and production varies markedly in different years. Instantaneous birth rates tend to be lower but more consistent for the more abundant species, instantaneous death rates show periods of negative mortality indicating an inadequacy of the model employed but explicable as hatching of resting eggs. K. cochlearis as the most successful species is explained as its perennial appearance and adaptation to the low annual temperature cycle found in the lough. The population succession and the annual occurrence of species differs in each year.

Zooplankton biomass of reservoirs in different trophic conditions in the State of São Paulo, Brazil

“…The dry weight of organisms of the same size may change according to the life cycle, nutritional state and reproductive conditions (Rocha, 1983), and the trophic conditions of the water (Andrew & Fitzsimons, 1992). Differences in the dry weight estimates of this study were attributed to both seasonal factors and each reservoir's trophic state, reflecting the nutritional state of the organisms.…”

Composição Da Comunidade Zooplanctônica Em Um Pequeno Corpo D’água Raso No Sul De Minas Gerais

“…O predomínio das espécies Hexarthra intermedia, Polyarthra aff. vulgaris e Brachionus falcatus em corpos d'águas rasos são geralmente comum (ANDREW; FITZSIMONS, 1992;KUCZYNSKA-KIPPEN, 2000;GREEN, 2003), justificando as maiores densidades das espécies no ambiente aquático em estudo. No entanto, SLÁDEČEK, (1983) afirma que as espécies do gênero Hexarthra e Conochilus ocorrem em águas poluídas utilizando como fonte de alimento as bactérias decompositoras de material orgânico e as partículas sólidas suspensas.…”

The zooplankton of the lower river Meuse, Belgium: seasonal changes and impact of industrial and municipal discharges

“…Several identification keys were used for these determinations (Pontin, 1978 ;Pourriot & Francez, 1986 ;Amoros, 1983 ;Harding & Smith, 1974 ;Dussart, 1969) . The biomass was estimated from regression equations relating dry weight to body length and from dry weight data available in the literature (Dumont et al, 1975 ;Pauli, 1989 ;Andrew & Fitzsimons, 1992) .…”