An angiosperm quality index (AQI) for Cantabrian estuaries

Angiosperms are an important biological parameter for establishing the status in transitional waters. Angiosperms grow from subtidal to upper intertidal zones and are sensitive to the most important pressures present in estuaries. A multi-metric for determining the status of Cantabrian estuaries has been developed by taking into account the angiosperms that live in these environments. This metric integrates two important directives: the Water Framework Directive (WFD) and the Habitats Directive. To be precise, the diversity of the existing habitats, the coverage in relative terms with respect to the optimal situation, and the loss of extension are considered in the metric. The application of the method to three Cantabrian estuaries subjected to different pressures demonstrates that the metric captures the degree of pressures of each estuary. The multi-metric method allows us to identify the type of problems to be tackled by the relevant authorities in the programme of measures of the river basin management plan.