Attheya armata along the European Atlantic coast - The turn of the screw on the causes of “surf diatom”

The “surf diatom” species Attheya armata (West) Crawford accumulations have been detected in the coasts of Galicia (NW Spain) in recent years. However, unlike in other parts of the world, the current knowledge of the phenomenon in European coasts remains disperse and scarce. A multiple approach has been used to monitor a sector of the Galician coast and to evaluate chemical and biological parameters in the environment, as well as under in vitro culture conditions, with the aim of studying the causes underlying these episodes. Contrary to the general assumption, our results indicate no direct relationship between the ephemeral accumulation episodes occurrences with the continental discharges or nutrient levels in beach waters. The isotopic reference values for coastal food web in Galicia allows to affirm with certainty that A. armata accumulations is dominate by the sediment dynamics.