Ramp disturbance–ramp response: a simple model for wetland disturbance ecology

Abstract

In the present study, we report on the responses of the picoplanktonic cyanoprokaryote Synechococcus sp. to a summer drawdown in a Mediterranean floodplain wetland, using water level decrease as a measure of the gradual increase of disturbance over time, defined as a ramp disturbance. Simulating the gradual confinement of fish biomass during the drought event in an enclosure study, we found that the density of Synechococcus did not change significantly in response to fish-mediated changes in trophic state and food web compared with a fishless control. Instead, we observed a positive correlation of water levels and Synechococcus abundance in all enclosures, indicative of a ramp response to the ramp disturbance. Planktonic organisms, although largely neglected by wetland scientists, seem to be very useful model organisms for identifying cause–effect mechanisms in wetland disturbance ecology.