Comparative sensitivity of the cnidarian Exaiptasia pallida and a standard toxicity test suite: testing whole effluents intended for ocean disposal

The sea anemone Exaiptasia pallida (formally Aiptasia pulchella) has been identified as a valuable test species for tropical marine ecotoxicology. Here, the sensitivities of newly developed endpoints for E. pallida to two unidentified whole effluents were compared to a standard suite of temperate toxicity test species and endpoints that are commonly used in toxicological risk assessments for tropical marine environments. For whole effluent 1 (WE1), a 96-h lethal concentration 50 % (LC50) of 40 (95 % confidence intervals, 30–54) % v/v and a 12-day LC50 of 12 (9–15) % v/v were estimated for E. pallida, exhibiting a significantly higher sensitivity than standard sub-lethal endpoints in Allorchestes compressa (96-h effective concentration 50 % (EC50) of >100 % v/v for immobilisation) and Hormosira banksii (72-h EC50 of >100 % v/v for germination), and a similar sensitivity to Mytilus edulis galloprovincialis larval development with a 48-h LC50 of 29 (28–30) % v/v. Sub-lethal effects of whole effluent 2 (WE2) on E. pallida pedal lacerate development resulted in an 8-day EC50 of 7 (3–11) % v/v, demonstrating comparable sensitivity of this endpoint to standardised sub-lethal endpoints in H. banksii (72-h EC50 of 11 (10–11) % v/v for germination), M. edulis galloprovincialis (48-h EC50 for larval development of 12 (9–14) % v/v) and Heliocidaris tuberculata (1-h EC50 of 13 (12–14) % v/v for fertilisation; 72-h EC50 of 26 (25–27) % v/v for larval development) and a significantly higher sensitivity than A. compressa immobilisation (96-h EC50 of >100 % v/v). The sensitivity of E. pallida compared to a standard test species suite highlights the value in standardising the newly developed toxicity test methods for inclusion in routine toxicological risk assessment of complex whole effluents. Importantly, this species provides an additional taxonomic group to the test species that are currently available for tropical marine ecotoxicology and, being a cnidarian, may represent important tropical marine environments including coral reefs.