Qualitative and quantitative methods for sampling zooplankton in shallow coastal estuaries

There are many techniques for collecting zooplankton, hence the data obtained using different methods can differ from each other. The effectiveness of quantitative and qualitative zooplankton sampling with the use of the Ruttner sampler and the Apstein plankton net was compared during a study conducted in the Vistula Lagoon. The analyzed zooplankton community comprised Crustacea and Rotifera species. No signifi cant differences (p = 0.5294, α = 0.05) in the qualitative composition of zooplankton samples collected with the Ruttner sampler and the Apstein plankton net were noted in the saltwater intrusion section. Significant differences (p = 0.0277, α 0.05) were observed in the freshwater inflow, indicating that the Ruttner sampler delivers more reliable results in zooplankton communities marked by greater qualitative variation. Significant differences (α = 0.05; p = 0.0008 for saline section and p = 0.0000 in freshwater section) in the effectiveness of quantitative sampling from both lagoon sections suggest that fewer individuals are collected with the plankton net than with the Ruttner sampler.