A Marine Biotic Index to Establish the Ecological Quality of Soft-Bottom Benthos Within European Estuarine and Coastal Environments

In this paper, a marine Biotic Index (BI) for soft-bottom benthos of European estuarine and coastal environments is proposed. This is derived from the proportions of individual abundance in five ecological groups, which are related to the degree of sensitivity/tolerance to an environmental stress gradient. The main difference with previously published indices is the use of a simple formula that produces a continuous Biotic Coefficient (BC) – which makes it more suitable for statistical analysis, in opposition with previous discreet biotic indices – not affected by subjectivity. Relationships between this coefficient and a complementary BI with several environmental variables are discussed. Finally, a validation of the proposed index is made with data from systems affected by recent human disturbances, showing that different anthropogenic changes in the environment can be detected through the use of this BI.