The quantitative contribution of discrete littoral habitats and the pelagic habitat to whole lake zooplankton abundance, biomass and diversity

This quantitative study investigated the contribution of discrete littoral habitats, the whole littoral and the Pelagic habitat to zooplankton abundance, biomass and diversity within shallow lakes. Intensive sampling was carried out in the main study lake, Enagh Lough East where samples were collected biweekly in the Alisma, Elodea, Gravel, Mud, Phalaris and Stone habitats using a quantitative littoral sampling method, the Active Tube and fifteen replicates were collected biweekly in the Pelagic habitat. In 2009 sampling was also carried out in Ballysaggart Lough and Lough Creeve to test the findings from the main study lake. The Active Tube has been designed to sample zooplankton quantitatively in discrete habitats within the littoral zone of lakes. It collects a representative sample of zooplankton within lake littoral habitats compared with the high margins of uncertainty associated with semi quantitative sampling methods. When compared with a commonly used method the Horizontal Timed Net Sweep, the Active Tube collected 50% more cladoceran species over three plant habitats than the Timed Net Sweep method and the Active Tube samples had cladoceran abundances per unit volume that were at least 2000 times greater than those collected using the Timed Net Sweep. The Active Tube method produces a more detailed description of littoral zooplankton assemblages than semi quantitative methods and it allows discrete littoral habitats to be described. In Enagh Lough East the discrete littoral habitats and the whole littoral habitat provided a greater contribution to zooplankton abundance, biomass and diversity than the Pelagic habitat per unit volume and in absolute values. The higher abundance, biomass and diversity values in the littoral habitats were due to the presence of resident littoral cladoceran species and not a result of peIagic cladoceran visitors undergoing diel horizontal migration. Littoral cladocerans made up half of the assemblage within the Pelagic habitat and 20% of the Pelagic habitat biomass. Cladoceran assemblages differed between each of the habitats. Findings from Enagh Lough East were tested in Ballysaggart Lough and Lough Creeve. Results from these test lakes strongly supported the findings in Enagh Lough East and indicated that a similarly important role of littoral zooplankton could be expected in other shallow lakes.EThOS - Electronic Theses Online ServiceGBUnited Kingdo