Evaluation of the meiobenthic copepod Bryocamptus zschokkei (Schmeil) as an ecologically-relevant test organism for lotic freshwaters

Despite proven utility as ecotoxicological testorganisms in marine systems, harpacticoidcopepods have not been used in freshwaterbiomonitoring. Here we assess the value ofBryocamptus zschokkei, a common member ofmeiofaunal stream communities, as a testorganism for lotic systems by measuring theeffects of copper on acute (survival ofovigerous females) and sub-lethal (offspringproduction, juvenile i.e. naupliar andcopepodite] development times) end points. Allovigerous females survived exposure atconcentrations <180 µg Cu l^–1, butat >180 µg Cu l^–1, mortalityincreased with exposure times up to 72 h;seventy-two and ninety-six hour LC50s wereidentical (290 µg Cu l^–1). After sixtydays, total offspring production per femaledeclined with increasing copperconcentration; no offspring were producedat 150 µg Cu l^–1 and significantlyfewer offspring were produced at 100 µg Cul^–1 compared with the control. In thejuvenile development tests, nauplii andcopepodites did not survive at 150 µg Cul^–1, but there was no significant effecton development times at lower Cu concentrations(0–100 µg Cu l^–1). Comparison oflaboratory-derived, toxicity end points withdata for B. zschokkei populations incopper-contaminated streams in south-westEngland, demonstrated that significant declinesin the number of surviving offspring closelymatched concentrations of copper across whichdeclines in field populations occurred. Theseresults indicate that B. zschokkei haspotential as an ecologically-relevant testorganism for lotic systems.