Control survival was good in all bioassays regardless of salinity (100% in FW, 2.5 and 10 ppt and 85±11, 90±6, 86±10
and 95±5% in 5, 15, 22 ppt and SW, respectively) attesting to the euryhalinity of this species.
For two (2.5 and 15 ppt) of the seven bio-assays, data did not allow for calculation of confidence intervals.
For one test (10 ppt) sufficient mortality could not be achieved within Cu solubility limits to estimate an LC 50.
The maximal dissolved Cu concentration at 10 ppt was 973 g/l and the highest mortality was 33±3%.
The data from this test is presented as >973 g/l in Figs. 1 and 2.
Calculated LC 50’s and confidence intervals (when available) display a biphasic pattern with increasing Cu tolerance from FW to 10 ppt and reduced Cu tolerance with salinity increasing from15 ppt to SW (Fig. 2A).
The concentration of DOC was constant across salinities, the H+ concentration decreased with increasing salinity while all other electrolytes increased (Table 1).
As salinity increased, so did pH and total CO2, resulting in an increased fraction of Cu in the form of Cu dicarbonate.
At 35 ppt, Cu carbonate and Cu dicarbonate combined to 87% of the total Cu (Table 2).
The two forms of Cu generally believed to be most toxic, Cu2+ and CuOH+, increased from FW to 2.5 ppt but then decreased with increasing salinity resulting in the lowest fractions in SW (Table 2).
Control survival was good in all bioassays regardless of salinity (100% in FW, 2.5 and 10 ppt and 85±11, 90±6, 86±10and 95±5% in 5, 15, 22 ppt and SW, respectively) attesting to the euryhalinity of this species. For two (2.5 and 15 ppt) of the seven bio-assays, data did not allow for calculation of confidence intervals. For one test (10 ppt) sufficient mortality could not be achieved within Cu solubility limits to estimate an LC 50.The maximal dissolved Cu concentration at 10 ppt was 973 g/l and the highest mortality was 33±3%. The data from this test is presented as >973 g/l in Figs. 1 and 2. Calculated LC 50’s and confidence intervals (when available) display a biphasic pattern with increasing Cu tolerance from FW to 10 ppt and reduced Cu tolerance with salinity increasing from15 ppt to SW (Fig. 2A).The concentration of DOC was constant across salinities, the H+ concentration decreased with increasing salinity while all other electrolytes increased (Table 1). As salinity increased, so did pH and total CO2, resulting in an increased fraction of Cu in the form of Cu dicarbonate. At 35 ppt, Cu carbonate and Cu dicarbonate combined to 87% of the total Cu (Table 2). The two forms of Cu generally believed to be most toxic, Cu2+ and CuOH+, increased from FW to 2.5 ppt but then decreased with increasing salinity resulting in the lowest fractions in SW (Table 2).
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