The zooplankton of a small tropical reservoir (Solomon, Dam, North Queensland): seasonal changes and the influence of water quality management measures

Samples were collected by duplicated vertical hauls (net diameter 50 cm; mesh size 90 um) in mid-afternoon at monthly or fortnightly intervals over 16 months. A total of 54 zooplankton species were identified. The Rotifera were the most diverse taxonomic group (35 species identified, including a new record for Australia, Mytilina acanthophora). However, rotifers were a generally unimportant fraction of the total biomass, except following seasonal or management induced perturbations, when they often recovered most rapidly. Cyclopoid copepods were the dominant zooplankters, although Cladocera became more significant following the introduction of artificial aeration to control cyanobacteria. Water temperature, flushing rates and phytoplankton species composition all influenced zooplankton abundance and the structure of the assemblage. The abiotic factors of flushing and thermal tolerance both contributed to an annual periodicity in the zooplankton.