Intra-annual variability and patchiness in living assemblages of salt-marsh foraminifera from Mill Rythe Creek, Chichester Harbour, England

Abstract. The areas of coastal marsh studied in Mill Rythe Creek, Chichester Harbour, southern England, support a fluctuating foraminiferal assemblage which, although similar to those recorded in other parts of the UK and the Atlantic seaboard of North America, has its own distinctive assemblage of species. This is due to the constantly high salinity of the water here. Unusually, these marshes do not receive freshwater input from a nearby river and thus are not subject to tidal fluctuations in salinity.

The mid-marsh Site 1 has a fauna consisting of typical marsh species, e.g., Jadammina macrescens, Trochammina inflata and Miliammina fusca. In addition, normal marine salinity allows Quinqueloculina oblonga to flourish and even dominate the fauna in most samples. The lower marsh Site 2 contains a typical marsh fauna dominated by hyaline forms. The dominance of Ammonia beccarii [aberdoveyensis] is most characteristic of the lower marsh, together with Haynesina germanica. The normal marine salinity of the marsh can again be confirmed by the high abundance of Quinqueloculina oblonga.

The results of a replicate sampling regime employed in this study clearly demonstrate the patchy nature of the living foraminiferal distribution in marsh environments over small lateral distances as well as the high seasonal variability of foraminiferal abundances.