Three species, Alona affinis, Disparalona rostrata and Leydigia leydigi comprised 97% of the benthic chydorid community in the River Thames UK. Benthic samples collected throughout the year provided estimates of their density, size distribution, individual length-weight relationships and biomass. Growth rates for each species, at several temperatures, were obtained from laboratory cultures. Separate regression equations (power functions) were calculated for each species at each temperature. Their combined annual secondary production was estimated using the increment-summation method, and was found to be 684 mg m-2 y-1. Eggs contributed most to total production for all species ranging from 57 % total (Leydigia leydigi) to 77 % total (Alona affinis). Patterns of daily production of the three species closely tracked those of biomass and density. Annual P : B ratios ranged from 22 (Disparalona rostrata) to 31 (Alona affinis) and are similar to the value of 20 suggested for multivoltine cladoceran zooplankters.
|Journal||Archiv fur Hydrobiologie|
|Publication status||Published - 1995|