Zooplankton community emerging from fresh and saline wetlands

Abstract

Salinity is a significant factor affecting aquatic species distribution and diversity. To quantify the impact of increasing salinity on the zooplankton community structure, the emergence of zooplankton community from fresh and saline wetlands under different salinity was examined. Sediments from three wetlands from the Upper South East of South Australia were exposed to salinity levels of 300 mg dm-3, 5000 mg dm-3 and 15 000 mg dm-3 for 21 days. After 21 days, more taxa had emerged from fresher wetland sediment than emerged from more saline wetlands. A reduction in the number of zooplankton species and their abundance was evident in the freshwater wetland sediment once salinity was increased from 300 mg dm-3 to 5000 mg dm-3. Species that emerged from freshwater sediment were mainly freshwater species and their number was signifi cantly reduced as salinity increased. Saline wetlands were colonised by more salt tolerant species such as Brachionus plicatilis, Trichocerca sp. and calanoid copepods. The results indicate that increasing salinity will potentially reduce freshwater zooplankton richness and the community will be shifted from freshwater species to more salt tolerant species.