Variations in the hatching response of rotifers to salinity and waterbird ingestion

Abstract

Climate change is increasing the salinity of waters in the Mediterranean region. This effect may negatively affect the resilience of aquatic communities and modify regional dynamics, favouring the colonization of salt-tolerant species. Our objective was to test the effects of salinity on the resilient capacity and dispersal response of rotifers at different temperatures through the study of their hatching success. Hatching responses are compared between diapausing eggs isolated from the sediments of two peridunal lakes and from waterbird faecal samples collected in the same area. Experiments were performed at two temperatures (15 and 25°C) with four salinity treatments (0.2, 1, 4 and 8 g L−1). Results showed species-specific hatching response of rotifers to salinity, which varied with temperature. No overall differences in hatching were observed between the lake sediments and waterbird faecal samples. However, the only diapausing eggs hatching from waterbird faecal samples were those isolated from faecal droppings of Anas platyrhynchos and A. clypeata. We observed that hatching success of Brachionus angularis was higher for dispersed diapausing eggs by waterbirds than for sedimentary diapausing eggs. Our results show that high water salinities and/or particular species of disperser waterbirds may limit the potential dispersal of rotifers by waterbirds.