Many organisms live in spatially delimited habitat patches, where local extinctions are compensated by dispersal and recolonization of empty habitat patches. To predict the dynamics of such metapopulations in an era of large environmental changes, it is essential to understand the key abiotic factors affecting local occurrence and temporal variation in patch occupancy. Here, we investigated the metapopulation dynamics of the marine copepod Tigriopus californicus, which is restricted to high intertidal and supralittoral rock pools. We monitored populations of T. californicus in northern California for almost 2 yr and observed pronounced seasonal changes in patch occupancy with <80% population turnover annually. Copepod occupancy depended on the area, depth and desiccation of pools and shore height of pools. Most local extinctions were due to pool desiccation, and the pools with an intermediate desiccation risk and low shore heights were the most frequently occupied. We highlight the significance of both the spatial position of pools (shore height) and their ephemerality in explaining occupancy pattern. © Inter-Research 2012.