Cancel Villamil, Johann J.
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Publication Effects of dam removal on fish communities in Puerto Rico streams(2021-07-07) Cancel Villamil, Johann J.; Locke, Sean; College of Arts and Sciences - Sciences; Santos Flores, Carlos J.; Blanar, Christopher; Department of Biology; Morales-BenÃtez, José J.The island of Puerto Rico has approximately 1,200 rivers and streams that total 9,187 river kilometers in 46 major drainage basins. The flow of these bodies of fresh water is interrupted by approximately 335 artificial barriers, some of which could potentially be removed. In this study we focused on studying the effects of dams and their removal on fish communities in Puerto Rico streams. This is a novel study because it is the first time that dam removal has been studied in a tropical island setting, as well as one that focuses on the removal of a low head dam in close proximity to the river mouth. We sampled fish communities in 15 sites in three rivers, where one had a dam that was going to be removed, one with a dam that was not going to be removed and an undammed control river. Sampling occurred during a three-year period, including periods before and after removal of the Cambalache dam in the RÃo Grande de Arecibo. A three-pass method with a backpack electro-fisher was used to sample fish communities, and fish were caught and identified to the species level when possible. After a total of 42 sampling events, a total of 27 fish species were collected, including seven native river species, 13 native estuarine species, and seven exotic species. Species richness was consistently higher in sites below dams as opposed to sites above them. Native river fish were dominant in all sites, especially above dams, while native estuarine species were uncommon above dams but common below them, and exotic species were uncommon in all locations. Immediately following removal of the Cambalache dam, species richness in the RÃo Grande de Arecibo increased from an average of five to nine fishes in sites above the former dam. Fish communities in two of the three sites above the former dam became more similar to communities below it due to the appearance of native estuarine species upstream, whereas prior to removal, estuarine species were absent above the dam. Dam removal was especially beneficial to native estuarine fish in that they could now utilize habitat formerly unavailable because of the dam. These results suggested that dam removal could be used in tropical islands to allow estuarine fish to have access to more habitat that may be inaccessible to them because of dams. For future studies, it is suggested this study be repeated with dams that are farther from the river mouth, or with medium dams in close proximity to the river mouth, to observe the effects of their removal on fish communities.