Affiliation:
1. Oxford University, United Kingdom; Instituto Nacional de Pesquisas Espaciais, Brazil
2. Universidade de São Paulo, Brazil
3. Instituto de Desenvolvimento Sustentável Mamirauá, Brazil
4. Instituto Nacional de Pesquisas Espaciais, Brazil
Abstract
ABSTRACT In a particular region within western Amazonia, Amazonian manatees (Trichechus inunguis) live in a floodplain environment that becomes inhospitable for them during the annual low-water season. To flee from it, they undergo a dangerous migration to a refuge while water levels are dropping fast. Our aim was to better understand the role of depth variation in this migratory process. We analyzed the sole tracking data on wild manatees (n=10 males), 30 years of Landsat images, a 14-year hydrograph and a 3-D bathymetric model. Migratory routes contained shallower segments, here called 'migratory bottlenecks', which dried out at the end of most lowering-water seasons, blocking the passage to the refuge. Manatees began migrating just in time to traverse the bottlenecks furthest away, suggesting they fine-tuned their departure so as to maximize time within the foraging home range without compromising safety. They apparently achieved this by estimating depth at the bottlenecks. Moreover, a bottleneck was created in >15 years, illustrating the environment's dynamism and the challenge this imposes upon manatees. Our results are probably generalizable to most of the species' range. We contend manatees possess an updatable cognitive map of their environment and are behaviorally plastic. Current dam-building plans, if implemented, would create more bottlenecks and make flooding less predictable, increasing manatee mortality from unsuccessful migrations. It would also partition the species into small populations, each prone to short-term extinction. The natural outcome would be the second species-level collapse. Economic growth should not come at the expense of the extinction of the iconic manatee.
Subject
General Agricultural and Biological Sciences
Reference39 articles.
1. The lesser of two evils: seasonal migrations of Amazonian manatees in the Western Amazon;Arraut E.M.;Journal of Zoology,2010
2. Amazonian manatee threatened with extinction by massive dam-building plan in the Amazon. Response to Winemiller et al. 2016.;Arraut E.M.;Science,2016
3. Sensoriamento remoto da dinâmica da circulação da água do sistema planície de Curuai/Rio Amazonas;Barbosa C.C.F.,2005
4. Geospatial analysis of spatiotemporal patterns of pH, total suspended sediment and chlorophyll-a on the Amazon floodplain;Barbosa C.C.F.;Limnology,2009
5. Seasonal breeding in the Amazonian manatee, Trichechus inunguis (Mammalia: Sirenia);Best R.C.;Biotropica,1982
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