Estuarine areas as nursery grounds for marine fish in a global change scenario: combining local and large-scale approaches

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Trophic links and nutritional condition of fish early life stages in a temperate estuary

Publication . Primo, Ana Lígia; Correia, Catarina; Marques, Sónia Cotrim; Martinho, Filipe; Leandro, Sérgio; Pardal, Miguel

The physiological and nutritional condition of fish larvae affect their survival and thus, the success of estuaries as nursery areas. Fatty acid composition has been useful to determine fish nutritional condition, as well as trophic relationships in marine organisms. The present study analyses the fatty acid (FA) composition of fish larvae during spring and summer in the Mondego estuary, Portugal. FA composition, trophic markers (FATM) and fish nutritional condition was analysed for Gobiidae and Sardina pilchardus larvae and the relationships with the local environment evaluated. Results showed that both taxa differed mainly in the stearic acid (C18:0) and eicosapentaenoic acid (EPA) content, with important amounts in Gobiidae and S. pilchardus, respectively. Gobiidae larvae presenting high nutritional condition and omnivore FATM. Fatty acid composition seems to be related with their natural habitat selection and food availability, while fish larvae nutritional condition also showed a strong link with the water temperature and presence of potential predators. This study suggests that FA composition can be a useful tool in assessing planktonic trophic relationships and in identifying species natural habitat.

2018Journal article

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Spatial distribution and seasonal patterns of the siphonophores Muggiaea atlantica and Muggiaea kochii in a temperate estuarine ecosystem

Publication . D'Ambrosio, Mariaelena; Primo, Ana L.; Pardal, Miguel A.; Martinho, Filipe; Guerrero, Elena; Marques, Sónia C.

This study analysed the distribution and abundance of both polygastric (asexual) and gonophores of the calycophoran siphonophores Muggiaea atlantica and Muggiaea kochii in the Mondego estuary (Portugal), as well as the influence of local environment and prey availability on the observed patterns. Samples were collected in three different zones of the estuary, from December 2013 to November 2015. In general, both species nectophores and total gonophores followed a similar trend, with higher abundances during spring-summer periods and increased densities in the downstream areas of the estuary, where the marine influence is stronger. Inter-annual differences occurred mainly for M. atlantica nectophores, which showed higher abundances in 2015, particularly in the upstream areas. Both species displayed a shift in the annual peak abundance, from bimodal in 2014 to unimodal in 2015. Patterns observed were not only strongly related with an increase of the marine influence in the estuary, but also with the presence of zooplanktonic prey, such as cirripede cypris, calanoid nauplius, Poecilostomatoida, and copepodites of Cyclopoida. This study represents a step towards a better knowledge of the biology and ecology of siphonophores.

2019Journal article

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