engleski

Bacterioplankton is significant food source for higher trophic levels in the floodplain lake during lotic conditions

This investigation examined interactions of microbes and metazooplankton components of the aquatic food web. The investigation was conducted in Lake Sakadaš in the Kopački Rit floodplain, Croatia. The samples were collected weekly at two sites, from the surface and from the bottom water layers during 11 weeks in spring 2008. Total number of bacteria was determined by epifluorescence while metazooplankton (rotifers, cladocerans, copepods and nauplii) counts were conducted by light microscopy. To describe physical and chemical environment, different variables were determined by standard methods: chlorophyll a, total suspended solids, biological oxygen demand, ammonia, nitrite, nitrate, Kjeldahl nitrogen, total phosphorus and dissolved oxygen concentrations, electrical conductivity, pH, water temperature and depth. Hydrological conditions were constantly changing between flow and flood pulses, and the lake was constantly connected with the River Danube. Such conditions limited phytoplankton development disabling its correlation with bacteria (ρ = -0.327, p = 0.163). Bacterial abundance was inversely related to rotifers (ρ = -0.673, p = 0.012), suggesting its control by top-down mechanisms. Constantly high bacterial abundance and in the same time lack of correlation with different environmental variables suggest their independence of currently developed hydrological conditions within the floodplain. So, it seems that bacterial biomass represent important food source for higher trophic levels in Lake Sakadaš, channelled through the rotifers.

Bacterioplankton; metazooplankton

Potvrda o koautorstvu izdana od strane HMD-a i korigirana stranica zbornika sažetaka je pohranjena kod autora.