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Projeto de investigação
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.
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.
Survival of Corbicula fluminea (Müller, 1774) in a natural salinity and temperature gradient: a field experiment in a temperate estuary
Publication . Crespo, Daniel; Leston, Sara; Martinho, Filipe; Pardal, Miguel A.; Dolbeth, Marina
The invasive bivalve Corbicula fluminea is described as a freshwater species but can colonize estuarine upper reaches. In a 46-day field experiment, the survival ability of the species along an estuarine gradient was tested. Our goal was to understand its tolerance limits in a transitional area and in which conditions a potential invasion in the estuary could thrive, in order to predict the potential threat of the species distribution and settlement along the freshwater–estuarine continuum. The Lethal Time (LT) method was adapted to this field test with success. The population held an adult stock in the most upstream areas of the estuary (salinity <0.5). Dispersal mechanisms allowed the species to be present in the downstream areas, however, with a different population structure as consequence of the interaction of the diverse physico-chemical gradients of the estuary, in particular different salinity and temperature combinations. During winter, the species was able to survive in all test sites, with practically no mortality, while in summer LT50 (median lethal time) changed considerably when comparing the upstream and the most downstream sites [82 days (predicted value) vs. 9 days, respectively]. Still, 100% mortality was never achieved, adding concern to the species invasion potential in this estuary.
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Fundação para a Ciência e a Tecnologia
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Investigador FCT
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IF/01410/2012/CP0173/CT0004