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Exposição da freira-das-Bermudas a poluentes orgânicos persistentes e oligoelementos : a influência da ecologia trófica e o impacto no sucesso reprodutor
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Abstract(s)
A poluição marinha constitui um dos maiores problemas ambientais atuais que afeta principalmente os predadores de topo. A Pterodroma cahow é uma ave pelágica outrora considerada extinta. A monitorização populacional a longo prazo revelou, no passado, a suscetibilidade da freira-das-Bermudas à contaminação por poluentes orgânicos (p,p’-DDT e metabolitos) e, mais recentemente, o insucesso de eclosão entre os casais reprodutores. O presente estudo visa avaliar o impacto da variação das dimensões dos ovos, de macro e oligoelementos (essenciais e não essenciais) no sucesso de eclosão e averiguar a possível influência da exposição a poluentes orgânicos persistentes, através da sua relação à ecologia trófica e características individuais. Durante a época de reprodução de 2019, foram recolhidas 36 cascas de ovos e amostras de sangue de 25% de indivíduos reprodutores. O estudo consta que cerca de 27% dos ovos não eclodidos pode dever-se à exposição de contaminantes. A variabilidade observada nas dimensões dos ovos não sugere qualquer relação com a probabilidade de eclosão. Observou-se a mobilização do macroelemento potássio e do oligoelemento essencial ferro das cascas de ovos durante o desenvolvimento embrionário, sugerindo que as mesmas podem funcionar como reserva. Os indivíduos com maior massa corporal apresentaram menores concentrações de p,p’-DDE, ΣPCBs e ΣOCPs, sugerindo o efeito de diluição. Houve uma relação negativa entre as concentrações de ΣPCBs e os níveis de δ15N. Apesar das concentrações de p,p’-DDE, ΣPCBs e ΣOCPs terem sido relativamente baixas, indivíduos com maiores concentrações estão suscetíveis a um menor sucesso reprodutor, sendo a probabilidade de eclosão menor.
Marine pollution is among the biggest environmental problems of today that mostly affects marine top-predators. The Pterodroma cahow is a pelagic seabird once considered extinct. The long-term population monitoring revealed, in the past, the Bermuda petrel’s susceptibility to contamination by organic pollutants (p,p’-DDT and metabolites) while, more recently, it reported the hatching failure of a consistent number of breeding pairs. This study aims at evaluating the impact of variation in egg size, as well as macro- and trace element concentrations (essential and non-essential) on the hatching success and to investigate the possible exposure to persistent organic pollutants, through its relationship with the trophic ecology and individual characteristics. During the breeding season 2019, 36 eggshells and blood samples from 25% of breeding birds were collected and analyzed. The findings showed that the fate of 27% of failed eggs could be related to the exposure to contaminants. The variability observed in egg characteristics do not suggest any relationship with the hatching success. Mobilization from the eggshells of the macro elements potassium and essential trace element iron during the embryonic development suggested that the eggshell can represent a reserve of elements for the embryo. The negative relationship between individual body mass and p,p’-DDE, ΣPCBs and ΣOCPs concentrations suggest the occurrence of a dilution effect. There was a negative relationship between ΣPCBs concentrations and δ15N levels. Although the concentrations of p,p’-DDE, ΣPCBs and ΣOCPs were relatively low, individuals with higher contaminant burden showed a lower reproductive success, being the hatchability of their eggs lower.
Marine pollution is among the biggest environmental problems of today that mostly affects marine top-predators. The Pterodroma cahow is a pelagic seabird once considered extinct. The long-term population monitoring revealed, in the past, the Bermuda petrel’s susceptibility to contamination by organic pollutants (p,p’-DDT and metabolites) while, more recently, it reported the hatching failure of a consistent number of breeding pairs. This study aims at evaluating the impact of variation in egg size, as well as macro- and trace element concentrations (essential and non-essential) on the hatching success and to investigate the possible exposure to persistent organic pollutants, through its relationship with the trophic ecology and individual characteristics. During the breeding season 2019, 36 eggshells and blood samples from 25% of breeding birds were collected and analyzed. The findings showed that the fate of 27% of failed eggs could be related to the exposure to contaminants. The variability observed in egg characteristics do not suggest any relationship with the hatching success. Mobilization from the eggshells of the macro elements potassium and essential trace element iron during the embryonic development suggested that the eggshell can represent a reserve of elements for the embryo. The negative relationship between individual body mass and p,p’-DDE, ΣPCBs and ΣOCPs concentrations suggest the occurrence of a dilution effect. There was a negative relationship between ΣPCBs concentrations and δ15N levels. Although the concentrations of p,p’-DDE, ΣPCBs and ΣOCPs were relatively low, individuals with higher contaminant burden showed a lower reproductive success, being the hatchability of their eggs lower.
Description
Dissertação de Mestrado apresentada no ISPA – Instituto Universitário para obtenção de grau de Mestre na especialidade de Biologia Marinha e Conservação.
Keywords
Poluentes Sucesso de eclosão Nicho trófico Pollutants Hatch success Trophic niche