MP8 Metals in the Environment: Dietary concerns in Aquatic Systems
Monday, 14 November 2005: 8:00 AM - 5:30 PM in Exhibit Hall

(PIN-1117-822356) Waterborne versus dietborne copper toxicity in the euryhaline copepod Acartia tonsa.

Pinho, G¹, Cardoso, C², Bianchini, A^{1, 2}, ¹ Programa de Pós-Graduação em Oceanografia Biológica, Rio Grande, RS, Brasil² Departamento de Ciências Fisiológicas, Rio Grande, RS, Brasil

ABSTRACT- The goal of the present study was to determine the relative importance of waterborne and dietborne copper toxicity in the euryhaline copepod Acartia tonsa in a wide range of salinity. Male and females adult copepods were acclimated to two different salinities (5 and 30), for at least one week. Temperature and photoperiod were fixed at 20°C and 16L:8D, respectively. Copper toxicity was determined using a standard static-renewal system. Groups of 10 acclimated copepods were exposed to different concentrations of copper (CuCl₂), for 48h, in four different ways: waterborne copper without food (group A), waterborne copper plus no–precontaminated food (Thalassiosira weissflogii; 2x10⁴ cells/mL) (group B), waterborne copper plus copper – contaminated food (group C), and copper – precontaminated food in a copper – free experimental medium (group D). Based on nominal copper concentrations, 48h-LC50 values (g/L) with respective 95% confidence interval were: 50.7 (37.8 – 67.8), 215.4 (129.4 – 241.1), 102.9 (86.4 – 122.6) and 4,803.1 (4,281.6 – 5,284.9) at salinity 5 in groups A, B, C, and D, respectively. At salinity 30, these values were 109.8 (73.8 – 141.2), 133.4 (78.6 – 170.7), 135.0 (84.2 – 184.2) and 6,731.1 (6,009.1 – 7,505.2), respectively. Results show that at salinity 5, 48h – LC₅₀ values were significantly lower than those at salinity 30 in groups A and D. These results show that the protective effect of salinity against acute copper toxicity is more evident when copepods are exposed to only waterbone or dietborne copper. They also indicate that waterborne copper is the main source of copper causing toxicity to copepods, since acute toxicity was approximately 100 and 70–fold higher when copepods were exposed to waterborne copper than to dietborne copper at salinity 5 and 30, respectively. Furthermore, acute copper toxicity was ∼ 2–fold lower when copepods were exposed simultaneously to waterborne and dietborne copper than when exposed to waterbone copper alone. Supported by International Copper Association; CNPq.

Key words: Acartia tonsa, copper, Biologic Ligand Model, dietborn