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

Abstract

Between 1991 and 1993, samples were collected upstream and downstream of the industrial basin and urban centre of Liege. Rotifers and crustaceans (cladocerans and copepods) were identified and counted. Their population dynamics were related to physical and chemical factors (temperature, oxygen, ammonium, nitrates, nitrites, phosphates) and to phytoplankton biomass . The zooplankton was dominated by rotifers ; crustaceans (cladocerans and copepods) were less abundant . There was a succession of groups and species, some thriving in the spring and others in summer or autumn . The dominant rotifer species were Brachionus calyciflorus Pallas, Brachionus angularis Gosse, Keratella cochlearis (Gosse) and Synchaeta spp . ; B . calyciflorus and B. angularis are spring species . K. cochlearis was present between May and November . Crustacean biomass was important in summer and autumn, but the faunal spectrum and biomass also varied with sampling location . Low spring and summer discharges allowed the phytoplankton to develop significantly . The zooplankton development followed a similar pattern . During low flow, when plankton populations become established, some declines in phytoplankton could only be explained by sedimentation and grazing pressure by zooplankton. Although these factors provided a good explanation of the longitudinal variation, some local conditions (e.g . oxygen deficit, high level of phosphate) also induced changes (e .g . industrial and municipal waste water discharge) .

Développement du phytoplancton, des Ciliés et des Rotifères sur deux sites de la Loire moyenne (France), en période d'étiage

“…Dans les programmes de surveillance, ou en cas de pollution industrielle, leur étude simultanée pourrait apporter des informations complémentaires. En effet, les Rotifères répondent très bien aux processus d'eutrophisation estivaux qui se manifestent dans les rivières, comme nous l'avons illustré en 1995 (Lair & Reyes-Marchant 1997) ; ils sont sensibles aux micropolluants organiques et inorganiques (Thomé et al 1993, Marneffe et al 1997, tandis que les Ciliés qui traduisent également l'influence des activités humaines (Pratt et al 1987), paraissent en outre plus sensibles aux perturbations mé-caniques qu'aux chocs chimiques (Sime-Ngando, comm. pers.…”

A case study of the planktonic communities in two hydrologically different oxbow lakes, Vistula River, Central Poland

“…It has been suggested that the apparent predominance of rotifers in rivers and floodplain lakes may be connected with their small size and relatively short generation time compared to the larger crustaceans (van Dijk and van Zanten, 1995;Lair, 2006;Radwan, 2004). In addition, rotifers appear to be better adapted to adverse conditions of lotic and semi-lotic habitats (Marneffe et al, 1996).…”

Assessment of Pollution in Sidi M'Hamed Benali Lake (Algeria) Based on Bioindicators and Physicochemical Parameters

“…It deserves a very detailed attention, considering which it very faded and is seriously threatened by the natural processes (weathering processes, precipitation rate, soil erosion) and the anthropogenic activities [1]. The latter, induce strong alterations of physicochemical characteristics and of biocenose diversity that could have dangerous consequences for the whole ecosystem [2][3][4]. Thus, they generate polluting elements which damage their use for drinking, bathing, industrial, agricultural, reaction or other purposes [5,6].…”

“…Zooplankton is a good indicator of changes in water quality because it is strongly affected by environmental conditions and responds quickly to changes in environmental quality [3,4,7,9,10]. Among zooplankton, some cladocères as Bosmina longirostris and Chydorus sphaericus are commonly used as eutrophic indicators of conditions [10].…”