Biological Indicators of Marine Environmental Health: Meiofauna – A Neglected Benthic Component?

This paper considers the use of meiofauna (benthic metazoa 45 to 500 μm in size) as biological indicators for monitoring marine environmental health. To date, this abundant and ubiquitous group of invertebrates has been largely neglected in applied sampling programmes; instead, emphasis has been placed upon more conspicuous biological components such as seagrass, macrofauna and epiphytes. In an attempt to redress this balance, this paper sets out three objectives: (1) to explain the reasons for selecting biological response indicators from across the whole spectrum of phylogenetic organisation, (2) to summarise those aspects of meiofaunal life-history and demography that render this group suitable for monitoring anthropogenic pollution and disturbance, (3) to suggest how to optimise the inclusion of meiofauna in monitoring programmes so that they provide maximum information for management purposes. To achieve these objectives the environmental impact assessment framework of Ward and Jacoby (1992) is adopted as a matrix into which the relevant components of meiofaunal ecology are fitted. Using this matrix, meiofauna are shown to have advantages that include their sessile habit, high species diversity, short generation time, direct benthic development and ubiquitous distribution. Disadvantages include their small size, high level of spatial and temporal variability, the potential cost of sample processing and the limited taxonomic literature accessible to non-specialist workers. The paper concludes with a discussion of sampling strategies and methods of analysis that may be used to efficiently incorporate meiofauna as biological response indices into environmental monitoring. Emphasis is placed on cost-effective techniques such as taxonomic minimalism.