Metacommunity dynamics of Ostracoda in temporary lakes: Overall strong niche effects except at the onset of the flooding period

Metacommunity research usually focuses on the structure of species assemblages and their influencing factors, chiefly environment and space. However, the temporal dynamics of metacommunities and their structuring processes are rarely investigated. Here, we analyze the temporal variations in a metacommunity of ostracods from temporary shallow lakes of the Iberian Peninsula. Our aims were to determine the variability of the ostracod assemblages throughout a hydrological cycle by means of partial triadic analysis (PTA), and to analyze the response of these communities to both environmental and spatial variables. The metacommunity was moderately stable through the study period, with larger variability between sites than between months. However, the metacommunity structure at the beginning of the hydroperiod was notably different from the rest of months. Species sorting was the predominant mechanism structuring the metacommunity through monthly samples, establishing a conspicuous separation between species that inhabit saline lakes and those preferring freshwater bodies. Spatial processes were negligible. Our results show the strength of a temporal approach in the study of metacommunities, against a single snapshot, stressing differences at the onset and the end of hydroperiod in temporary water bodies, but still surpassed by species sorting effects under a steep environmental gradient.