Giant otter population responses to habitat expansion and degradation induced by a mega hydroelectric dam

摘要: Large hydroelectric dams are major drivers of habitat loss and degradation in lowland Amazonia. Hydroelectric reservoirs reduce the available for terrestrial species, but create new open-water shoreline lake that can potentially boost populations aquatic semi-aquatic such as threatened giant otter (Pteronura brasiliensis). To assess impacts mega-dams on this apexpredator, we surveyed population across 443,772-hectare Balbina Reservoir central Brazilian Amazonia between 14 25 years after reservoir creation. We compared changes area estimated size pre- postfilling stages. The dam created � 3525 islands increased surface total perimeter to otters by a factor 62.7 8.9, respectively. Some damming, however, post-filling was only twice greater than before filling 4.5 times smaller would be predicted given density dens quantified at neighbouring undisturbed used surrogate pre-filling phase. observed mismatch proportional increase much newly is likely due low quality terms fish prey productivity scarcity suitable sites denning territory demarcation. This should considered strategic environmental impact assessments planned managing existing future hydropower development tropical forests.