Dear colleagues,
We are pleased to announce our recent article published on-line (first) in the journal Ecological Indicators:
The first confirmed decline of a delphinid population from Brazilian waters: 2000-2015 abundance of Sotalia guianensis in Guanabara Bay, South-eastern Brazil. Alexandre F. Azevedo, Rafael R. Carvalh, Maja Kajin, Monique Van Sluys, Tatiana L. Bisi, Haydée A. Cunha, José Lailson-Brito Jr.
Abstract:
The
abundance of Guiana dolphins (Sotalia
guianensis) in Guanabara Bay, Rio de Janeiro, South-eastern Brazil, was
investigated during the period 2000 – 2015 using mark-recapture models applied
to photo-identification data. A combination of Pradel’s model and Pollock’s
robust design was applied to estimate abundance and other population parameters,
such as apparent survival (Φ), capture probability (p) and seniority
probability (γ). Total population size was estimated by correcting the
estimates derived from the Pradel robust design model for the
proportion of marked individuals in the population. The corrected abundance estimates decreased
drastically (37%) between 2000 (62, 95% CI 59-65) and 2015 (39, 95% CI 37-40),
and can be explained by a combination of low survival and recruitment rates.
Determining the ultimate causes for the decline in this Guiana dolphin
population is difficult, but the likely reasons are of anthropogenic nature,
such as by-catch, habitat degradation, intense traffic of vessels and exposure
to immunosuppressive and endocrine-disrupting pollutants. We provide the first quantitative
evidence of population decline in a delphinid from Brazilian waters. Conservation and
management actions are urged to change this scenario. Other local dolphin populations
in Brazil, which are exposed to the same impacts, may also be currently declining
or are expected to do so in the near future. For this reason, we emphasize that
anthropogenic
impacts upon estuarine/coastal species that exhibit site fidelity warrant
greater attention, because such impacts may lead to the same negative scenario
observed in Guanabara Bay.
Best Regards,
Alexandre
--
Dr. Alexandre de Freitas Azevedo
Laboratório de Mamíferos Aquáticos e Bioindicadores - MAQUA
Faculdade de Oceanografia, Universidade do Estado do
Rio de Janeiro
Rua São Francisco Xavier, 524 sala 4002E
Maracanã, Rio de Janeiro, 20550-013, RJ, Brasil
azevedo.alex@uerj.br55 21 2334-0065 - 2334-0795
55 21 99742-4993