title: Byssal detachment underestimates tolerance of mussels to toxic compounds.
abstract: Mussels are sedentary organisms attached to solid substrata by means of byssus threads. Mussels detached from their substratum tend to reattach by producing new byssus threads. Therefore, in bioassays using mussels, if the test animals are in an unattached status, increased byssogenic activity would expose their soft body parts to the toxic compound used. We test the tolerance of two mussel species (Mytilopsis leucophaeata and Mytilus edulis) to an oxidizing biocide (chlorine) and show that detached mussels are 24-28% less tolerant than byssally attached ones. Detached mussels also showed higher oxygen consumption, filtration rate, foot activity, byssus thread production and byssogenesis index, parameters which are associated with valve opening. A review of literature showed that most of the published data on toxicity against heavy metals and biocides are generated using unattached mussels. The data, therefore, represent an underestimation of the toxicity of the tested compound. Correction data are presented for chlorine tolerance of Dreissena polymorpha, Mytilopsis leucophaeata and Mytilus edulis. The present study suggests the importance of maintaining mussels in their attached status, while undertaking toxicity bioassays.
authors.affiliation: Department of Animal Ecology and Ecophysiology, Institute for Wetland and Water Research, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands. s.rajagopal@science.ru.nl
authors.forename: S
authors.initials: S
authors.lastname: Rajagopal
authors.forename: G
authors.initials: G
authors.lastname: van der Velde
authors.forename: M
authors.initials: M
authors.lastname: van der Gaag
authors.forename: H A
authors.initials: HA
authors.lastname: Jenner
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001681:Biological Assay / Q000379:methods*; D049872:Bivalvia / Q000187:drug effects* / Q000502:physiology*; D002713:Chlorine / Q000633:toxicity*; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D009426:Netherlands; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D015203:Reproducibility of Results; D013045:Species Specificity
chemical_list: D002713:Chlorine