Growth, reproduction and mortality in marine littoral Collembola at different salinities

ABSTRACT. 1. A comparative study was performed on growth, reproduction and mortality of three species of marine littoral Collembola: the grassland species, Isotoma viridis (Bourlet), the littoral Hypogastrura viatica (Tullberg) and the intertidal Anurida maritima (Guérin), at different salinities.
2. I. viridis and H. viatica both occur in salt marshes that are only inundated by seawater at very high tides. The first species lives in the higher less saline area and the second in the lower area, where during summer brackish and even hypersaline conditions may occur. The intertidal A.maritima is mainly found at salinities similar to the local seawater.
3. I.viridis and H.viatica both show maximal growth and reproduction and a very low mortality at low salinities, but the latter species is better adapted to higher salinities. A difference between A.maritima and the other two species is that A.maritima is unable to survive freshwater conditions; rather it has an ecological optimum at salinities similar to seawater.
4. A salt-marsh population of I.viridis showed a better survival and a slightly better growth at saline conditions than an inland population of this species.
5. We suggest that H.viatica , living in a very unstable environment, can be considered as a typical r-strategist, while A.maritima , living in a predictable habitat, is more a K-strategist.