Conservation and management of migratory fauna and dams in tropical streams of Puerto Rico

Greathouse, E. A., C. M. Pringle, and J. G. Holmquist.
2006. Conservation and management of migratory
fauna: dams in tropical streams of Puerto
Rico. Aquatic Conservation 16:695–712.

1. Compared to most other tropical regions, Puerto Rico appears to have dammed its running waters decades earlier and to a greater degree. The island has more large dams per unit area than many countries in both tropical and temperate regions (e.g., 3x that of the U.S.), and the peak rate of large dam construction occurred two and three decades prior to reported peak rates in Latin America, Asia and Africa. 2. Puerto Rico is a potential window into the future of freshwater migratory fauna in tropical regions, given the island’s extent and magnitude of dam development and the available scientific information on ecology and management of the island’s migratory fauna. 3. We review ecology, management and conservation of migratory fauna in relation to dams in Puerto Rico. Our review includes a synthesis of recent and unpublished observations on upstream effects of large dams on migratory fauna and an analysis of patterns in free crest spillway discharge across Puerto Rican reservoirs. Analyses suggest that large dams with rare spillway discharge cause near, not complete, extirpation of upstream populations of migratory fauna. They also suggest several management and conservation issues in need of further research and consideration. These include research on the costs, benefits and effectiveness of simple fish/shrimp passage designs involving simulating spillway discharge and the appropriateness of establishing predatory fishes in reservoirs of historically fishless drainages.

Water Withdrawn From the Luquillo Experimental Forest, 2004

Crook, Kelly E.; Scatena, Fred N.; Pringle, Catherine M. 2007. Water Withdrawn From the Luquillo Experimental Forest, 2004. U.S. Department of Agriculture, Forest Service, International Institute of Tropical Forestry. Gen. Tech. Rep. IITF-GTR-34.

This study quantifies the amount of water withdrawn from the Luqillo Experimental Forest (LEF) in 2004. Spatially averaged mean monthly water budgets were generated for watersheds draining the LEF by combining long-term data from various government agencies with estimated extraction data. Results suggest that, on a typical day, 70 percent of water generated within the forest is diverted before reaching the ocean. This is up from an estimated 54 percent in 1994. Analysis showed that up to 63 percent of average monthly stream runoff is diverted from individual watersheds during drier months. Watersheds with large water intakes have the most dramatic decrease in streamflow, particularly the Río Espiritu Santo watershed, where 82 percent of median flow is diverted.

Transforming tropical rivers: an environmental perspective on hydropower development in Costa Rica

Anderson E, Pringle C, Rojas M (2006) Transforming tropical rivers: an environmental perspective on hydropower development in Costa Rica. Aquatic Conservation-Marine and Freshwater Ecosystems 16: 679–693

1. Tropical rivers are increasingly being altered by hydropower dams. In Costa Rica, more than 30 hydropower plants were built during the 1990s and more dams are being proposed. Hydropower dams currently provide more than 80% of electricity consumed by the country’s 4 million residents, yet most of Costa Rica’s hydropower potential remains untapped. 2. Ecological consequences of dams in Costa Rica stem primarily from river fragmentation, stream de-watering, and downstream hydrological alterations. Dams affect distribution and abundance of aquatic biota, especially migratory species. Cumulative effects of multiple dams on individual river basins, especially in the northern part of the country, are also of concern but have not been adequately documented. 3. In light of recent hydropower development, we recommend conservation strategies that protect remaining free-flowing rivers, call for assessment of ecological impacts of dams on a broader scale, encourage research on aquatic systems and sustainable hydropower technologies, and promote the development of methods for estimating environmental flows for Costa Rican rivers. Copyright # 2006 John Wiley & Sons, Ltd.
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