Fossil testate amoebae in coastal deposits in the UK: implications for studies of sea‐level change

Abstract

AbstractAssemblages of testate amoebae in UK saltmarshes are strongly correlated with elevation and flooding duration, suggesting that if adequately preserved in sediments they may be used as accurate sea‐level indicators. To examine the preservation of testate amoebae in the fossil record in coastal environments, subsamples were collected from a range of coastal sites around Britain, including saltmarsh, coastal reedswamp, isolation basin, back‐barrier and coastal raised bog sites. The results showed that testate amoebae are present in the fossil record, although in variarble species diversities, concentrations and states of preservation. Testate amoebae were found to be well preserved in isolation basin infills and coastal raised bog deposits, where diverse assemblages (>20 taxa) were recorded. In the upper part of the isolation basin sequence from Loch nan Corr, northwest Scotland, the testate amoebae assemblages showed a greater degree of sensitivity to transitional salinity changes than existing foraminferal and larger testate amoebae data sets. This implies that testate amoebae, particularly small to medium‐sized specimens (15–300 µm), may hold considerable potential for sea‐level reconstruction in these environments. Preservation of testate amoebae in a freshly sampled core of saltmarsh sediment from South Wales was reasonable, although test distribution decreased significantly in abundance below 18 cm. The assemblage composition was similar to that found in the contemporary surface environment. The preservation of testate amoebae in saltmarsh and coastal reedswamp deposits of mid‐Holocene age was variable and generally poor. Partial dehydration of the sediment samples may account for this. Further studies are required to examine the palaeoecology and distribution of testate amoebae in similar coastal settings, to strengthen these preliminary findings. Copyright © 2002 John Wiley & Sons, Ltd.