PARENT SESSION

2M - Monitoring of function and structure
Poster Hall
8:30 AM - Wednesday, 30 April 2003
Chair: Schulz, R.¹, ¹

(WEP/151) Cooper effects on population dynamics of three-spined stickleback (Gasterosteus aculeatus) in lotic mesocosms.

Roussel, Helene¹, Catel, Florian¹, Bonzom, Jean-Marc¹, ¹ INERIS, Verneuil-en-Halatte, France

ABSTRACT- Anthropic sources of copper includes emission from industry (mine, smelters, foundries), urbanism (buildings, waste water) and agriculture (algaecide, fungicide, feed supplementers). The aquatic ecosystems, as a receptor, can be contaminated by copper. Yet, very little information is known on the ecological effects of copper on natural populations of aquatic ecosystems, especially fishes. In the present study we are looking at the effect of copper on fish population (Gasterosteus aculteatus) over a long sub lethal exposure period. The stream mesocosm experiment consist of 18 months of contamination (April 2002 to October 2003). Continuous contamination is applied in triplicates at four different concentrations (0, 5, 25 and 75 g/L). Per mesocosms, 70 adult fishes were introduced during the setting up period. Six months after the beginning of the contamination, a similar catch effort was applied on each mesocosms. Preliminary results show that, at concentrations of 75, 25 and 5 g/L, average number of individuals was respectively 33%, 20% and 1% higher than in the controls (containing an average of 480 fishes). Average fish body length was significantly different for fish exposed to 75g/l (3 cm, SD = 0.7) and to 5 g/L (2.5 cm, SD = 0.9) than for the control (2.6 cm, SD = 0.9). However, no significant difference between 25 g/L and control was showed (2.6 cm, SD = 0.7). It is necessary to correlate those findings with other biotic and abiotic factors measured in this study, such as zooplankton, macroinvertebrates, plants dynamics, etc. to understand fully the stickleback population dynamics.

Key words: mesocsms, Gasterosteus aculeatus, copper, population dynamics