Jornal de Ecossistema e Ecografia

Abstrato

The Distribution Of Contemporary Saltmarsh Foraminifera In A Macrotidal Estuary: An Assessment Of Their Viability For Sea-Level Studies

Hayley Mills, Jason Kirby, Simon Holgate, and Andrew Plater

An analysis of dead benthic foraminiferal assemblages and associated environmental variables is presented to establish the controls on species distribution and zonation on two macrotidal saltmarshes in the Mersey estuary with the aim of evaluating the use of foraminifera in reconstructing past sea levels. The combined results from five contemporary transects from two sites illustrate that where there is a sufficient elevational range, foraminifera distribution and zonation shows a good relationship with altitude, with a high-to-middle marsh zone characterised by Haplophragmoides wilberti , Jadammina macrescens, and Miliammina fusca, and a low marsh zone composed of similar agglutinated species with calcareous species including Brizalina spp., Elphidium spp., and Haynesina spp. Cluster analysis and partial Redundancy Analysis (pRDA) reveals that the elevational control decreases with respect to other environmental variable inter-correlations when the sampling elevation range is reduced. It is proposed that this is a key issue for macrotidal environments when the contemporary sampling range represents a small proportion of the spring tidal range (i.e. <10%). Limiting the contemporary dataset to agglutinated species only, a tidal level transfer function can be obtained which offers acceptable predictability and precision (r2jack = 0.79, RMSEPjack = 0.13 m) for the reconstruction of past sea level.