1Department of Marine Ecology, Göteborg University, Kristineberg Marine Research Station, 450 34 Fiskebäckskil, Sweden
2Hafok AB, 179 61 Stenhamra, Sweden
3Marine Monitoring AB at Kristineberg, 450 34 Fiskebäckskil, Sweden
4Department of Systems Ecology, Stockholm University, 106 91 Stockholm, Sweden