ASSESSING AND MONITORING ECOLOGICAL COMMUNITY HEALTH IN MARINE SYSTEMS: Fid-Bau Portal

ASSESSING AND MONITORING ECOLOGICAL COMMUNITY HEALTH IN MARINE SYSTEMS

Hewitt, J. E. / Anderson, M. J. / Thrush, S. F.

The increased potential for long‐term degradative change associated with large‐scale diffuse impacts in urban marine environments highlights the need to develop methods for assessing the ecological significance of any observed changes. This study defines “health” on the basis of the range of communities observed along gradients of anthropogenic impacts. This definition identifies both acute effects and broader scale degradation in community structure. Three multivariate constrained ordination techniques were used to assess changes in communities occurring along an anthropogenic disturbance gradient of stormwater pollution in two different habitats (estuaries and harbors). All three techniques detected changes, even when historical data sets, not specifically designed for the purpose, were utilized. Comparison with five diversity indices suggested that the multivariate approach was more successful in defining change and, thus, ecological health. Moreover, the information can easily be examined for changes in individual species, or for changes in function, trophic status, or biomass/size structure, improving interpretation of the ecological consequences of change. As this multivariate approach allows for monitoring community composition to determine whether sites are improving or degrading over time, it would be useful for aiding management decisions and assessing the efficiency of management actions. While this study occurred in one region only, the approach should be able to be utilized in other marine (or freshwater or terrestrial) systems where commensurable regional‐scale multivariate databases exist.