FORAMINIFERAL SPECIES DENSITIES AND ENVIRONMENTAL VARIABLES IN AN ESTUARY

Abstract

A pilot study of foraminiferal species densities in the Choptank River, Maryland, a part of the Chesapeake Bay estuarine system, indicated that the density of Elphidium clavatum decreased progressively upstream, while the densities of Ammobaculites exiguus and Ammonia beccarii varied little. Three stations were selected for more detailed analysis.Each station was sampled monthly for foraminiferal density for 12 months, and temperature, salinity, oxygen, and chlorophyll a, b, and c were measured. A general multiple regression‐analysis of variance model containing parameters for environmental variables, station differences, overall periodic differences, and the interaction of station and periodic differences was statistically compared to several more restricted models, with separate analyses for each species.The set of environmental variables is significant at the 95% level for all three species. None of the variables is significant individually. However, the relatively large values of the regression coefficients for the chlorophylls, especially b, suggest that the amount and kind of available food is important in determining species densities.All three species exhibit periodicity, and for each species the periodicity is different at the three stations. Restricted models containing 15 parameters are sufficient to account for the observed species densities in each case.