Integrative environmental assessment of the impact of Pasaia harbour activities on the Oiartzun estuary (southeastern Bay of Biscay)

Abstract

In this study an integrative approach has been applied for the analysis of water quality degradation within a harbour area. A combination of marine hydrodynamics, chemistry and ecotoxicological knowledge has been used to validate the applicability of new tools to help harbour environmental managers. These novel methodologies have been applied to Pasaia harbour, the second most important harbour of the Basque Country, located in the Oiartzun estuary (southeastern Bay of Biscay), selected as a pilot zone. Water residence time inside the harbour domain has been estimated by means of hydrodynamic numerical modelling. Water quality assessment has been complemented by labile metal fraction evaluation at four stations inside the harbour domain, using Diffusive Gradients in Thin-Films (DGTs). Besides, sediment metal concentration has been determined and their potential adverse biological effects have been tested by laboratory bioassays: 10-day acute survival test with marine amphipods (Corophium multisetosum) for whole-sediments and 48-hour sea urchin (Paracentrotus lividus) embryo-larval assay for sediment elutriates. The shortest residence times (two days) were obtained in the outer harbour and along the channel of the estuary. The metal contamination gradient measured by DGTs discriminated the outer station, located in the channel of the estuary, as the less contaminated, which is in accordance with the shortest residence time at this station. The innermost stations were characterised by higher contaminant concentration in sediment, together with higher residence times and greater toxic effects. (C) 2011 Elsevier B.V. All rights reserved.