Exploring hydrodynamics and suspended particulate matter at shallow shellfish estuaries of Galicia, NW Spain

Marine resources of the Atlantic coast of Galicia (NW Spain) are controlled by the efficient transport of nutrients through upwelling processes across multiple coastal inlets known as Rias. In the shallow regions of these Rias, estuaries are dominated by tide and fluvial forcings, creating sand sediment accumulations with a profitable substrate for shellfish ecosystem. These resources are heavily harvested by locals, playing a significant role in the economy of the region. Over the last decade, these coastal ecosystems have degraded, as observed by the lower production of commercial shellfish species. Among multiple factors, changes in suspended particulate matter trends and sediment stability, both driven by local hydrodynamic conditions, emerge as potential contributors. However, these factors have been barely studied, despite their susceptibility to be affected by climate change and anthropogenic interferences. 

In this study, we aim to enhance our knowledge of hydrodynamic processes in Ria’s estuarine regions by actual in situ measurements, with the final goal of contributing to an efficient resilience of the local shellfish community. For this purpose, we deployed a set of mooring stations measuring turbidity, current velocities, water level, and temperature, in three traditionally exploited estuaries with varying fluvial-ocean influence on the southern margin of Ría de Arousa. The obtained dataset spans a spring timeframe with changing weather conditions and is combined with measurements from meteorological and oceanographic permanent stations in the area from public institutions. The ongoing data analysis focuses on the role of tidal and fluvial processes on suspended particulate matter dynamics, examining how it varies over tide cycles and specific events, and identifying discrepancies between locations that may impact shellfish habitat quality. The acquired dataset will also help to validate a hydrodynamic model, which will be essential to explore suspended particle matter behaviour and biogeochemical cycles in the region under the projected climate change scenarios.