Role of the source community for the recovery of seagrass ssociated meiofauna: a field colonisation experiment with seagrass mimics in Diani Beach, Kenya

Abstract

Seagrass communities are subject to frequent disturbances that can affect the associated fauna. Seagrass loss in Kenya has been mainly due to extensive grazing by the sea urchin Tripneustes gratilla, leading to habitat fragmentation. The challenge is whether the system can recover fully and function as before. Density, diversity and community structure of meiofauna were studied to evaluate the ability of the ecosystem to recover its associated fauna. Artificial seagrass mimics were planted in natural, replanted and bare seagrass patch types. The associated meiofauna was harvested at different colonisation time intervals (min. 2 days–max. 21 days). Significantly different meiofauna densities between the patch types and the colonisation days were found whereas the harpacticoid copepod densities were only significantly affected by colonisation time. Meiofauna densities on the seagrass mimics recovered quickly in all patch types, i.e. after four days of colonisation their densities were comparable to those on natural seagrasses, but they exhibited an unstable, cyclical pattern. Initial communities consisted mainly of opportunistic non-phytal taxa. Passive and active migrations were deduced for harpacticoid copepods. We recommend the ecosystem approach as seagrass-associated meiofauna (and copepods) responded relatively quickly to new substrates, providing the surrounding (source) communities remains undisturbed.