Desiccation Resistance inTigriopus californicus(Copepoda, Harpacticoida)

In field populations and controlled laboratory microcosms, the supralittoral copepodTigriopus californicusdemonstrated the ability to recover populations from evaporated splashpools. The response to either seawater or rainwater introduction occurred mainly within 24 h, regardless of copepod abundance or substrate material (mixed sediment or dried samples of the algaEnteromorpha compressa). As a proportion of available individuals, the response was quite consistent over all life-history stages. However, egg-carrying females andadult males showed the greatest net increase in individual numbers due to their abundance in source (dried) materials.Enteromorpha compressatreatments hydrated with seawater yielded significantly greater re-animation (P<0•05), suggesting a response to food resources rather than moisture or salinity alone. Overall, 10•7±8•5% (mean±SD) of individuals were re-animated following hydration. While a slight percentage, the tremendous density of individuals trapped in dried splashpools probably still yields sufficient numbers of effective intra-pool recolonization. Such a response may be more practical for population endurance in ephemeral supralittoral habitats than reliance on environmental influences (waves, precipitation or transport on coincident invertebrates) or the deposition of encysted eggs.