The Brazilian codling (Urophycis brasiliensis) is the target of an important artisanal fishery in Uruguay. In the present study we analysed the feeding habits of this species over a 2-year cycle. The samples were obtained from landings of the artisanal fishery at two sites on the Uruguayan coast: one representing a transitional habitat between estuarine and marine conditions (Piria´polis), the other representing a typical marine ecosystem (La Paloma). Different approaches were considered (Index of Relative Importance, IRI; graphical methods and multivariate techniques of cluster analysis and Principal Component Analysis). The ontogenetic changes in the diet were also assessed. Stomach contents of 870 individuals were analysed and a total of 24 prey species identified. The shirmp Artemesia longinaris has the highest IRI (89.9%) score followed by Cynoscion guatucupa (IRI ¼ 4.3%). Molluscs were only marginally represented (IRI < 0.01%). Both the graphical method of Corte´s and the method of Amundsen indicate the specialization of Brazilian codling to A. longinaris. However, a trend to a generalist diet evolves in bigger fishes, which also consume fishes in important quantities, mainly C. guatucupa. Moreover, opportunism is occasionally present both seasonally and spatially, and responds to variations of the availability of prey items throughout its distribution. U. brasiliensis predation plays an important role in the trophic dynamics of the SW Atlantic ecosystem. It is dependent on shrimp for feeding, a reason for an integrated management of coastal habitat and fisheries of both resources. The dependence of Brazilian codling, mainly when it is small, on shrimp calls for an integrated management of both the coastal habitat and fisheries.
A B S T R A C TThe seasonal dynamics of the fish community in the Pando estuary on the Uruguayan coast were studied in relation to environmental sampled monthly between May 2002 and June 2003. Individuals collected were identified, and classified into stages (juveniles, adults) and functional groups. Relationships between community dynamics and environmental variables were evaluated using uniand multivariate techniques. Twenty-one species, mostly freshwater stragglers, estuarine and marine migrants were collected. The most abundant species were Micropogonias furnieri, Mugil platanus, Paralichthys orbignyanus and Brevoortia aurea and were represented by juveniles. The community varied seasonally with rapid shifts in spring and autumn associated with changes in temperature and salinity. Significant correlations between abundance and temperature may be related to the timing of life cycle events. In this estuary, the salinity appears to play a key role in the functional structure and in the use of the habitat by juveniles. This is relevant for the definition of estuaries as nursery areas: this definition is context-dependent and is determined by the salinity conditions.
R E S U M OFoi estudado a dinâmica sazonal da comunidade de peixes em relação as variáveis ambientais do estuário Pando, localizado na costa uruguaia. Os peixes foram amostrados mensalmente entre maio de 2002 e junho de 2003. Os indivíduos coletados foram identificados e classificados em estágios (jovens, adultos) e grupos funcionais. Relações entre a dinâmica da comunidade e as variáveis ambientais foram avaliadas utilizando-se técnicas uni-e multivariada. Vinte e uma espécies foram coletadas, principalmente visitantes de água doce, estuarinas e marinhas migratórias, sendo as mais abundantes e representadas por juvenis: Micropogonias furnieri, Mugil platanus, Paralichthys orbignyanus e Brevoortia aurea. A comunidade variou sazonalmente com rápidas mudanças na primavera e no outono, associadas à variações de temperatura e salinidade. Correlações significativas entre abundância e temperatura parecem estar relacionadas com a sincronizaçao de eventos dos ciclos de vida. Neste estuário a salinidade parece desempenhar um papel-chave na estrutura funcional e uso do habitat por juvenis. Este fato é relevante para a definição dos estuários como áreas de criadouro e pela influencia da salinidade sobre o ciclo da ictiofauna local.
Weight-length relationships are presented for 12 fish species from a subsystem of the Rı´o de la Plata estuary in Uruguay. This study provides new maximum lengths for three species and a new reference for the weight-length relationship of one species. U.S.
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