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.

Effect of nutrition on toxicity of contaminants to the epibenthic amphipod Melita plumulosa.

The amphipod Melita plumulosa is commonly used to assess the toxicity of contaminated sediments. Seven-day-old M. plumulosa are <1 mm in size, and during 10-day tests in sandy sediments with low nutritional value, starvation can cause >50% mortality. In sediment toxicity tests, therefore, it can be difficult to determine if toxicity is due to contaminants or starvation, particularly in contaminated sandy sediments. This study investigated the influence of amphipod age and food addition on amphipod survival in toxicity tests. The 4-day LC(50) increased linearly from 120 to 470 microg/L when M. plumulosa age at the beginning of the test increased from 5 to 30 days. The addition of food as algae or fish food did not significantly affect the sensitivity of 11-day-old M. plumulosa (11-d Mp) to dissolved copper over 4 days in water-only tests. The survival of 11-d Mp in water-only tests over 10 days was poor without feeding, but when fed fish food, the 10-day LC(50) was 76 +/- 15 microg/L. In sediment tests, feeding 0.063 mg fish food/amphipod on days 3 and 7 of 10-day tests consistently resulted in greater than 80% survival of 11-d Mp for a range of clean, sandy sediments, which had low amphipod survival without added food. Algae were not always suitable as a food source, as their growth can be stimulated by nutrients released from sediment and was inhibited by contaminants. The toxicity of most contaminated sediments was not ameliorated by the addition of food, suggesting that food addition was suitable for inclusion in routine testing protocols for this amphipod.

Variation in, and causes of, toxicity of cigarette butts to a cladoceran and microtox.

Cigarette butts are the most numerically frequent form of litter in the world. In Australia alone, 24-32 billion cigarette butts are littered annually. Despite this littering, few studies have been undertaken to explore the toxicity of cigarette butts in aquatic ecosystems. The acute toxicity of 19 filtered cigarette types to Ceriodaphnia cf. dubia (48-hr EC50 (immobilization)) and Vibrio fischeri (30-min EC50 (bioluminescence)) was determined using leachates from artificially smoked cigarette butts. There was a 2.9- and 8-fold difference in toxicity between the least and most toxic cigarette butts to C. cf. dubia and V. fischeri, respectively. Overall, C. cf. dubia was more inherently sensitive than V. fischeri by a factor of approximately 15.4, and the interspecies relationship between C. cf. dubia and V. fischeri was poor (R(2) = 0.07). This poor relationship indicates that toxicity data for cigarette butts for one species could not predict or model the toxicity of cigarette butts to the other species. However, the order of the toxicity of leachates can be predicted. It was determined that organic compounds caused the majority of toxicity in the cigarette butt leachates. Of the 14 organic compounds identified, nicotine and ethylphenol were suspected to be the main causative toxicants. There was a strong relationship between toxicity and tar content and between toxicity and nicotine content for two of the three brands of cigarettes (R(2 )> 0.70) for C. cf. dubia and one brand for V. fischeri. However, when the cigarettes were pooled, the relationship was weak (R(2) < 0.40) for both test species. Brand affected the toxicity to both species but more so for V. fischeri.