The toxicity of the three antifouling biocides DCOIT, TPBP and medetomidine to the marine pelagic copepod Acartia tonsa

Abstract

Copepods, the largest group of pelagic grazers, are at risk from exposure to antifouling biocides. This study investigated the toxicity of the antifouling biocides 4,5-dichloro-2-octyl-1,2-thiazol-3(2H)-one (DCOIT), triphenylborane pyridine (TPBP) and 4-[1-(2,3-dimethylphenyl)ethyl]-1H-imidazole (medetomidine) to the copepod Acartia tonsa, using mortality and egg production as endpoints. The toxicity ranking for mortality was as follows: DCOIT (LC50 57 nmol l(-1)) = TPBP (LC50 56 nmol l(-1)) > medetomidine (LC50 241 nmol l(-1)). Egg production was more sensitive than mortality to TPBP (EC50 3.2 nmol l(-1)), while DCOIT and medetomidine inhibited egg production at roughly the same concentrations (72 and 186 nmol l(-1) respectively). Furthermore, TPBP seems to affect egg hatching directly which was not the case for DCOIT and medetomidine. DCOIT and medetomidine might pose an environmental risk as they have been reported to occur in different exposure scenarios or analytical surveys at concentrations only 2-3 times lower than the respective EC10. Reported environmental concentrations of TPBP are few but clearly lower than the EC10 values reported here, suggesting current risk of TPBP to copepods to be moderate.

Mortality of Calanus helgolandicus: Sources, differences between the sexes and consumptive and nonconsumptive processes

“…While the consumption of a copepod by most predators typically involves the removal of the entire animal from the water column, including consumption by fish, fish larvae, jellyfish, and chaetognaths (Bonnet et al , ), other copepod species (Daan et al ; Boersma et al ), and even via cannibalism (Bonnet et al ); nonconsumptive mortality, that is mortality not caused by predation, tends not to lead to the immediate removal of the body of the animal, and hence typically results in a carcass. This nonconsumptive mortality can result from death from old age (Rodríguez‐Graña et al ), disease, and parasitism (Kimmerer and McKinnon ), the ingestion of toxic prey (Kâ et al ), exposure to environmental pollutants (Cohen et al ; Wendt et al ), and physical stresses such as during extreme weather events (Dubovskaya et al ; Bickel et al ; Tang et al ).…”

“…Carcasses present in the water column may represent copepods that have died after being attacked or stung by predators and this mortality is included in nonconsumptive counts. Indeed, nonconsumptive sources of death can lead to a substantial proportion of zooplankton carcasses present in the water column (Wheeler 1967;Elliott et al 2010;Elliott and Tang 2011a;Daase et al 2014). Conversely, mortality estimates typically calculate removal of individuals from the water column by any means, including differential advection of the life stages as well as their consumption by predators.…”

The Interannual Changes in the Secondary Production and Mortality Rate of Main Copepod Species in the Gulf of Gdańsk (The Southern Baltic Sea)

“…The gelatinous zooplankton was the main cause of mortality variability observed in deep coastal sampling station located near south-west of Plymouth, UK [54]. Non-consumer mortality may result from death caused by age [55], diseases and parasitism [56], exposure to environmental pollution [57], and physiological stress [58]. Field and laboratory studies show that non-consumptive factors can account for 25 to 33% of the total death rate among adult copepods [59].…”

The Interannual Changes in the Secondary Production and Mortality Rate of Main Copepod Species in the Gulf of Gdańsk (The Southern Baltic Sea)

“…The gelatinous zooplankton was the main cause of mortality variability observed in deep coastal sampling station located near the southwest of Plymouth, UK [55]. Nonconsumer mortality may result from death caused by age [56], diseases, and parasitism [57], exposure to environmental pollution [58], and physiological stress [59]. Field and laboratory studies show that nonconsumptive factors can account for 25-33% of the total death rate among adult copepods [60].…”