| |
Presented at the NABS Annual meeting, Athens, Georgia, 2003
in Conservation Ecology
Ecological impacts of a diversion dam on a tropical stream.
E.P. Anderson, C.M. Pringle, and M.C. Freeman. Institute of Ecology, University of Georgia, Athens, GA 30602
Many developing countries have recently experienced a dramatic increase in the construction of diversion dams for hydroelectric power. In Costa Rica, diversion dams have been constructed or planned for half of the country’s major watersheds. Although the ecological, social, and economic impacts of large dams with in-channel reservoirs have been well documented, the impacts of smaller diversion dams are less understood. Most of these smaller dams require a substantial amount of discharge to be diverted from the main river channel, leaving it de-watered over a distance of several kilometers. We assessed ecological effects of a medium-sized diversion dam (16 megawatts) on the Puerto Viejo River on Costa Rica’s Caribbean slope. Surveys of fishes, shrimps, macroinvertebrates and algae were conducted throughout a four kilometer de-watered (90-95% discharge removed) reach. Preliminary results indicated that the diversity and abundance of fishes increased with downstream distance from the dam. Fish assemblages closest to the dam were dominated by catfish (Rhamdia spp.), whereas a mullet (Agonostomus monticola) and a poecilid (Poecilia gillii) were abundant towards the end of the de-watered reach. Shrimp abundance also increased with distance from the dam. Results will be used to determine how aquatic biota may be compromised by de-watering of streams associated with diversion dams.
|
|
