Mercury, selenium and stable isotopes in four small cetaceans from the Southeastern Brazilian coast: Influence of feeding strategy.
Dolphins are good bioindicators of the contamination status of marine ecosystems, since their dietary and habitat plasticity in both coastal and offshore ecotypes provide information on the trace elements levels originated from natural and anthropogenic sources. In this context, this study aimed to investigate provides mercury (Hg), selenium (Se) levels, trophic ecology and feeding environments of four small cetaceans (Tursiops truncatus, Steno bredanensis, Sotalia guianensis and Pontoporia blainvillei) inhabiting the central-northern coast of Rio de Janeiro State, southeastern Brazil. For the latter, δ15N and δ13C stable isotopes were used as indicators in this regard. Stable isotope values indicate that the four studied species have distinctive foraging habitats, coastal and least coastal, and occupy different trophic positions. The significant relationship found between muscle Hg and δ15N suggests that individual foraging preference remains relatively constant for the studied dolphin species over extended periods. The individual prey size and species are probably responsible for the differences found in Hg and Se concentrations in muscle tissue among all dolphin species. The vulnerable small coastal cetacean, P. blainvillei, which feeds on small teleost fish and squid, presented the lowest muscular Hg concentrations (less than 3.5 μg g-1dry wt.). Meanwhile, S. bredanensis is more likely to uptake large amounts of trace elements among the four dolphin species, due to its feeding habits mainly being large offshore fish that accumulate high amounts of trace elements in organs and tissues. Differences found between Hg concentrations in fetus-mother pairs were much higher in S. guianensis than in P. blainvillei, suggesting that maternal contribution of Hg via placenta was more significant for the former.
Departamento de Química, Pontifícia Universidade Católica do Rio de Janeiro, RJ 22453-900, Rio de Janeiro, Brazil. Electronic address: gilbert-souza@hotmail.com.
Gilberto
G
Baptista
Laboratório de Ciências Ambientais, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ 28013-602, Brazil. Electronic address: helena.kehrig@pq.cnpq.br.
Helena A
HA
Kehrig
Laboratório de Ciências Ambientais, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ 28013-602, Brazil. Electronic address: anadibeneditto@gmail.com.
Ana Paula M
APM
Di Beneditto
Universidade Federal do Estado do Rio de Janeiro, Programa de Pós-Graduação em Ciências Biológicas - Biodiversidade Neotropical, 22290-240, Rio de Janeiro - RJ, Brazil. Electronic address: rachel.hauser.davis@gmail.com.
Rachel A
RA
Hauser-Davis
Laboratório de Ciências Ambientais, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ 28013-602, Brazil. Electronic address: marcelogaa@yahoo.com.br.
Marcelo G
MG
Almeida
Laboratório de Ciências Ambientais, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ 28013-602, Brazil. Electronic address: crezende@uenf.br.
Carlos E
CE
Rezende
Instituto Oswaldo Cruz/FIOCRUZ, Pavilhão Mourisco - sala 122, Rio de Janeiro, RJ 21040-360, Brazil. Electronic address: gemmlagos@gmail.com.
Salvatore
S
Siciliano
Leibniz Center for Tropical Marine Ecology - ZMT, Bremen, 28359, Germany. Electronic address: jailson.moura@zmt-bremen.de.
Jailson F
JF
de Moura
Departamento de Química, Pontifícia Universidade Católica do Rio de Janeiro, RJ 22453-900, Rio de Janeiro, Brazil. Electronic address: isabel@puc-rio.br.
Isabel
I
Moreira
D000818:Animals; D050681:Bottle-Nosed Dolphin / Q000378:metabolism*; D001938:Brazil; D002247:Carbon Isotopes / Q000032:analysis*; D017753:Ecosystem; D005247:Feeding Behavior; D005260:Female; D005399:Fishes; D008297:Male; D008628:Mercury / Q000032:analysis*; D009132:Muscles / Q000737:chemistry; D009587:Nitrogen Isotopes / Q000032:analysis*; D012643:Selenium / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D014874:Water Pollutants, Chemical; D008628:Mercury; D012643:Selenium
Environmental risk assessment; Foraging habitat; Marine mammal; Trace elements; Trophic position; Tropical Western South Atlantic Ocean