Studies on the production ecology of several mollusc species in the Estuarine Firth of Forth

Abstract

The thesis, given in two volumes, deals with., the population ecology of the macrofaunal mollusc species : Macoma balthica (L. ). Cerastoderma edule (L. ). Mya arenaria(L. ), Retusa obtusa (Montagu) and Hydrobia ulvae (Pennant) studied at fourteen stations on Torry Bay, a large intertidal area in the estuarine Firth of Forth, over the period January, 1975 to February, 1977. These species occupy differing ecological niches within the estuarine ecosystem. The environmental factors at the stations, which represent the range of available habitats in the area, are described in Chapter 2. This chapter also outlines the statistical techniques used in ascertaining the relationships between the factors studied. The population dynamics and magnitude of the growth, flesh condition, production and productivity of each species are given in Chapters 3-5. These chapters also discuss the environmental factors affecting the ecology of the species. Multivariate correlation and regression techniques have been used to describe the factors which influence the species' production ecology. The anomalous production ecology of M. balthica found in the Forth Estuary (Chapter 3) was further studied by a field mark and recapture experiment and multivariate laboratory experiments (Chapter 6). Chapter 6 also discusses the mode of feeding of this bivalve in relation to its ecological preferences and describes a small study on heavy metal pollution within M. balthica. The discussion in Chapter 7 gives general conclusions from the studies and their implications in estuarine productivity. Features common to the population ecology of the five species are discussed and a food web detailing the role of the benthic macrofauna on Torry Bay is given.