Chronic copper toxicity in the estuarine copepod Acartia tonsa at different salinities

Abstract

Chronic Cu toxicity was evaluated in the euryhaline copepod Acartia tonsa. Male and female copepods were exposed (6 d) separately to different combinations of Cu concentration and water salinity (5, 15, and 30 ppt) using different routes of exposure (waterborne, waterborne plus dietborne, and dietborne). After exposure, groups of one male and three female copepods were allowed to reproduce for 24 h. In control copepods, egg production augmented with increasing water salinity. However, egg hatching rate did not change. Copper exposure reduced egg production and hatching rate in all water salinities tested, but the reproductive response was dependent on the route of Cu exposure. Median effective concentration (EC50) values for egg production after waterborne exposure were 9.9, 36.8, and 48.8 µg/L dissolved Cu at water salinities of 5, 15, and 30 ppt, respectively. For waterborne plus dietborne exposure, they were significantly higher (40.1, 63.7, and 109.9 µg /L, respectively). After dietborne exposure, approximately 40% decrease in egg production was observed, independently of Cu concentration and water salinity tested. At water salinities of 5 and 30 ppt, egg hatching rate reduced after waterborne exposure, together or not with the dietborne exposure. At water salinity of 15 ppt, Cu toxicity was only observed after dietborne exposure. Data indicate that egg production is a more reliable reproductive endpoint to measure chronic Cu toxicity in copepods than egg hatching rate in a wide range of water salinities. They also suggest that both water salinity and route of Cu exposure should be taken into account in the development of a chronic biotic ligand model version for estuarine and marine environments.

Influence of Salinity and Dissolved Organic Carbon on Acute Cu Toxicity to the Rotifer Brachionus plicatilis

“…Using the same species, B. plicatilis, the 24-h Cu LC50 values were a factor of 1.5 higher at elevated salinities (20−29 ppt) when compared to lower salinities (6−15 ppt). 4 Hall et al 12 and Lauer and Bianchini 55 both demonstrated that elevated salinity increased LC/EC50 values in estuarine copepods (Eurytemora af f inis and Acartia tonsa, respectively). Similarly in vertebrates, a higher salinity also correlated with higher LC50 values in larval topsmelt, Atherinops af f inis, 17 and 96-h LC50 values in juvenile mummichog fish, Fundulus heteroclitus.…”

Dietary toxicity of metals in aquatic animals: Recent studies and perspectives

“…In a more recent study, the chronic reproductive toxicity of Cu was evaluated in A. tonsa following 6 days of exposure to different combinations of Cu concentration, salinity (5,15, and 30 ppt), and routes of exposure (waterborne, waterborne plus diet-borne, and diet-borne) [15]. The EC50 values for egg production after waterborne exposure were 9.9, 36.8, and 48.8 g/L at salinities of 5, 15, and 30 ppt, respectively, and they were significantly higher (40.1, 63.7, and 109.9 g/L, respectively) for waterborne plus diet-borne exposure.…”

Mechanisms of copper accumulation in isolated mantle cells of the marine clam Mesodesma mactroides

“…Copper concentration tested (5 mM) was shown to correspond to the 96-h LC20 for the marine clam M. mactroides after 96 h of exposure to Cu (96-h LC50: 5.8 mM total Cu; 5.2 mM dissolved Cu) under the same experimental conditions as employed in the present study (Aline Fernandes Alves de Lima, 2007, Master's thesis, Universidade Federal do Rio Grande, Rio Grande do Sul, Brazil). Copper as CuCl 2 (Merck) was added to the water 3 h prior to the clam's introduction in the experimental medium, as previously reported [21][22][23][24]. Every 24 h, the experimental medium was 100% renewed with fresh medium prepared as described above.…”