Species Assemblages in Saltmarsh Ponds in Western Iceland in Relation to Environmental Variables

The fauna and flora of 63 saltmarsh ponds in western Iceland were investigated. Forty-five taxa were identified. A DECORANA analysis of presence/absence of species showed salinities to be the chief determinants of species composition. Salinities were highly variable, but minimum salinities appeared to be most critical, although maximum salinities as well as elevation of ponds had additional significant effects. The majority of the species are marine species, most of which are commonly found under fully marine conditions. Minimum salinities experienced can therefore be expected to be particularly critical for such species. Some species were shown to have a distinct modal abundance pattern with the mode at intermediate salinities. Species richness was positively related to salinities. A shift in composition of dominant angiosperms indicating a reduction in salinities had taken place between 1977-78 and 1991. The species composition of the ponds shows similarities to that of estuaries although significant differences can be seen. The species composition also shows similarities to that recorded from saltmarsh ponds in Britain, Netherlands and Germany