The use of Jadammina macrescens (Brady) and Balticammina pseudomacrescens Bronnimann, Lutze and Whittaker (Protozoa : Foraminiferida) as sea-level indicators

In studies of foraminiferal distributions in saltmarshes in New England and Atlantic Canada, Balticammina pseudomacrescens and Jadammina macrescens ha ve formerly been grouped as Trochammina macrescens. This study recognises t hem as distinct species and shows that they have significantly different di stributions on the surface of saltmarshes in Maine. Here, relative abundanc es of J. macrescens correlate with tidal elevation (r(2) = 0.55, p = 0.00), whereas those of B. pseudomacrescens do not (r(2) = 0.03, p = 0.34). There fore, J. macrescens is a better sea-level indicator in Maine marshes than B . pseudomacrescens. In Menunketesuck River marsh, Connecticut, a clear vert ical zonation of saltmarsh foraminifera is absent, which hinders interpreta tion of fossil data. This study shows that, in Maine, separating B. pseudom acrescens and J. macrescens in counts of fossil data facilitates the detect ion of transgressional and regressional events in the biostratigraphical re cord and, hence, the reconstruction of local sea-level histories. Regional variability between northern and southern New England saltmarshes necessita tes the establishment of local reference sets of modem analogue data to aid palaeoecological interpretations. (C) 1999 Elsevier Science B.V. All right s reserved.