Annual biomass loss of the loose-lying red algal community via macroalgal beach casts in the Väinameri area, NE Baltic Sea

Abstract

A unique, commercially exploited loose-lying red algal community in the Baltic Sea is situated in Kassari Bay, the Väinameri area (NE Baltic Sea). These macroalgae have been harvested since the 1960s, and continuous monitoring of biological characteristics of the community has been carried out to enable sustainable exploitation of this marine living resource. In this study the losses of the red algal community through beach casts were calculated from the estimates of the amounts of marine wrack on the NE shores of Saaremaa Island from April to November 2002. The community loss through beach casts was estimated at ∼5000 tonnes wet weight per year. These annual losses via wrack deposition represent ∼3% of the community standing stock in summer. Commercial exploitation in the form of bottom trawling of the loose algal community made up only 20% of the losses due to beach casts.