title: Novel antifouling agent--zinc pyrithione: short- and long-term effects on survival and reproduction of the marine polychaete Dinophilus gyrociliatus.
abstract: The recent ban on TBT in boat antifouling paints has resulted in a large employment of the biocide zinc pyrithione (ZnPT) as substitute. Despite concerns of its environmental toxicity at ultra-trace concentrations, ZnPT has received little attention, as it was assumed to photo-degrade easily. However, recent evidence has suggested that ZnPT degrades only partially, and persists in the marine environment, especially where the influence of light is limited, such as in harbours. Short-term acute toxicity tests and life table response experiments (LTREs) were performed to evaluate the effects of ZnPT on the polychaete Dinophilus gyrociliatus at both individual and population level. The 96h-LC(50) values for ZnPT on D. gyrociliatus were 7.8 and 11.5nM under dark and 12h light/12h dark conditions, respectively. In LTREs, laboratory cultured cohorts of D. gyrociliatus were exposed to sublethal concentrations of ZnPT (0.5 and 1nM) and compared to a control cohort. The survival among individuals exposed to the highest concentration decreased already during the 2nd week of life with respect to the control. The effects of the biocide on fecundity were even more evident: ZnPT caused a considerable reduction in both the exposed groups. The demographic approach applied here succeeded in identifying ZnPT effects both on the biological cycle and on the growth potential of polychaete D. gyrociliatus. The net growth rate (R(0)) appeared to be the demographic parameter most sensitive to ZnPT, as the biocide exposure was associated with a sharp decline of R(0) in both the 0.5 and the 1nM groups (-41% and -63%, respectively) in comparison to the control cohort. The population growth rate lambda (often used as an index of population fitness) and the life expectancy e(0) were also significantly reduced, while ZnPT exposure did not affect the generation time T. These results highlight the potential ecological threat posed by the biocide ZnPT, even at the very low tested concentrations, which are already detectable in some European marinas.
authors.affiliation: Dipartimento di Biologia Animale, Università degli Studi di Modena e Reggio Emilia, via Campi, 213/D, 41125 Modena, Italy. marco_marcheselli@yahoo.it <marco_marcheselli@yahoo.it>
authors.forename: Marco
authors.initials: M
authors.lastname: Marcheselli
authors.forename: Francesco
authors.initials: F
authors.lastname: Conzo
authors.forename: Marina
authors.initials: M
authors.lastname: Mauri
authors.forename: Roberto
authors.initials: R
authors.lastname: Simonini
mesh_terms: D000818:Animals; D057219:Biofouling / Q000517:prevention & control*; D003624:Darkness; D004305:Dose-Response Relationship, Drug; D005298:Fertility / Q000187:drug effects / Q000502:physiology; D008027:Light; D008386:Marine Biology; D009942:Organometallic Compounds / Q000633:toxicity*; D011077:Polychaeta / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology*; D011157:Population Dynamics; D011725:Pyridines / Q000633:toxicity*; D012098:Reproduction / Q000187:drug effects / Q000502:physiology; D015996:Survival Rate; D013997:Time Factors; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D009942:Organometallic Compounds; D011725:Pyridines; D014874:Water Pollutants, Chemical; C010423:pyrithione zinc