Efecto del viento en el coeficiente de atenuación de la luz en el agua para el saco interno de la Bahia de Cádiz
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The influence of wind velocity on water column light attenuation coefficients within the inner Bay of Cádiz
Over 90 % of Cádiz Inner Bay, a shallow (3 m MLW), tidal lagoon, is inhabited by benthic macrophytes. The survival and productivity of these populations, and therefore their role in the ecosystem, strongly depends on the availability of light. Thus, to understand the ecology of benthic macrophytes within the bay it is fundamentally important to know how which factors affect benthic light availability. In this study, we analysed a historical database of benthic light availability (2006 - 2010), revealing strong evidence for a relation between wind and attenuation of light in the water column. Furthermore, 4 deployments of in situ measurements, carried out under different wind conditions, were examined so as to provide indications as to the mechanisms involved in the interaction between wind and light attenuation. The results demonstrate a clear relationship between the magnitude and direction of the wind and the attenuation of light. Waves generate higher orbital velocities at the sediment surface, presumably enhancing resuspension, which in turn, significantly affects the concentration of suspended solids in the water column and the water column attenuation coefficient. In conclusion, wind-wave generation and the subsequent resuspension of sediments appear to be one of the important mechanisms controlling light availability within Cadiz Inner Bay.