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Transfer and accumulation of paralytic and amnesic shellfish toxins in secondary consumers of the marine trophic chain
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Paralytic and amnesic shellfish toxins can enter in the marine trophic chain by filterfeeding and benthic organisms. Then due to trophic interrelationships the toxins are transferred to theirs predators. In the last instance, top predators (marine mammals and sea birds) can be intoxicated after fed on primary and secondary consumers. The wild horse mackerel (Trachurus trachurus) was collected in NW and S Portuguese coast between September of 2009 and March of 2010. The results show for the first time that horse mackerel can accumulate high concentrations of PSTs in theirs gastrointestinal tract. Which increased the requirement of evaluated the dynamics of accumulation and elimination of PSTs in secondary consumer fish. Thus aquaculture fishes, white sea breams, were fed with toxin-contaminated cockles. After 5 days of toxin exposure, the fishes were fed with non toxic cockles during 10 days. In this feeding experiment, an increasing of toxin concentration over the exposure period was noticed in the fish gastrointestinal tract. B1 and dcSTX were the only toxins continuously detected during the exposure/elimination period, which reveal a slower elimination than the others PSTs. These two PSTs were also the main toxins in the mackerel toxin profile, which may suggest a specific PSTs elimination by fish species. Although AST were not detected in any mackerel specimen, in octopus (Octopus vulgaris) specimens captured in the same fishing area, domoic acid (DA) was detected in the digestive glands. This accumulation of DA in the octopus was previously identified. However this is the first time that DA was detected during periods of absence of ASP events. Plus DA was predominantly found in the cytosol which increased the evidence of a retention mechanism. Since DA as a hydrophilic compound should be easily release. This thesis supplies relevant data to the growing knowledge on the dynamics of accumulation and elimination of PSTs and AST in secondary consumers and on the toxin transfer in the marine food web.
Paralytic and amnesic shellfish toxins can enter in the marine trophic chain by filterfeeding and benthic organisms. Then due to trophic interrelationships the toxins are transferred to theirs predators. In the last instance, top predators (marine mammals and sea birds) can be intoxicated after fed on primary and secondary consumers. The wild horse mackerel (Trachurus trachurus) was collected in NW and S Portuguese coast between September of 2009 and March of 2010. The results show for the first time that horse mackerel can accumulate high concentrations of PSTs in theirs gastrointestinal tract. Which increased the requirement of evaluated the dynamics of accumulation and elimination of PSTs in secondary consumer fish. Thus aquaculture fishes, white sea breams, were fed with toxin-contaminated cockles. After 5 days of toxin exposure, the fishes were fed with non toxic cockles during 10 days. In this feeding experiment, an increasing of toxin concentration over the exposure period was noticed in the fish gastrointestinal tract. B1 and dcSTX were the only toxins continuously detected during the exposure/elimination period, which reveal a slower elimination than the others PSTs. These two PSTs were also the main toxins in the mackerel toxin profile, which may suggest a specific PSTs elimination by fish species. Although AST were not detected in any mackerel specimen, in octopus (Octopus vulgaris) specimens captured in the same fishing area, domoic acid (DA) was detected in the digestive glands. This accumulation of DA in the octopus was previously identified. However this is the first time that DA was detected during periods of absence of ASP events. Plus DA was predominantly found in the cytosol which increased the evidence of a retention mechanism. Since DA as a hydrophilic compound should be easily release. This thesis supplies relevant data to the growing knowledge on the dynamics of accumulation and elimination of PSTs and AST in secondary consumers and on the toxin transfer in the marine food web.
Descrição
Tese de mestrado, Ecologia Marinha, 2010, Universidade de Lisboa, Faculdade de Ciências
Palavras-chave
Fitoplâncton Microalgas Toxinas paralisantes (PSP) Teses de mestrado