Is summer growth reduction related to feeding guild? A test for a benthic juvenile flatfish sole (Solea solea) in a temperate coastal area, the western Wadden Sea

Flatfish species are an important target for fisheries. During their juvenile stage they concentrate in coastal nursery areas. Food conditions in these areas are an important factor determining habitat quality and ultimate survival. Recently, growth reduction in summer has been observed in plaice, Pleuronectes platessa, feeding on both epibenthic and benthic prey. In the current study, we test the hypothesis that summer growth reduction is a consequence of a reduced availability of benthic prey by analysing summer growth in a fully benthic feeding flatfish, juvenile sole (Solea solea). Summer growth was studied for contrasting years with respect to preceding winter water temperature conditions to exclude possible irreversible non-genetic adaptations of growth to water temperature. Individual growth, estimated from otolith daily rings, was compared with predictions of maximum growth at the prevailing temperature. In line with expectations, 0-group sole showed strong summer growth reduction, supporting the notion that summer growth reduction is related to feeding modes. Summer growth reduction underlines the importance of a good definition of how and over what time period growth as indicator of habitat quality is estimated and compared