Fish assemblage in a temperate estuary on the uruguayan coast: seasonal variation and environmental influence

Foi 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.The 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 uni- and 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

Composição, abundância e biomasa sazonal da assembleia de peixes no subestuário do Solís Chico (Estuário do Río de la Plata, Uruguay)

The large estuaries can present long narrow branches called subestuaries or tidal creeks. These types of subsystems are distributed along the Uruguayan coast of the Río de la Plata estuary and are very important as nursery and refuge areas for fish. For the first time, the seasonal composition and abundance of the fish community of the Solís Chico subestuary was studied by using beach and gill nets. Fourteen species, mainly euryhaline (86%) presented a significant representation of juvenile stages. The fish community was dominated by Odontesthes argentinensis, Platanichthys platana, Mugil liza, Brevoortia aurea, Micropogonias furnieri and Paralichthys orbignyanus, similar to adjacent subestuaries. While Micropogonias furnieri and B. aurea were the most abundant species, some other species were rarely caught. A seasonal variation of the fish assemblage abundance was detected, with higher values in autumn showing a positive correlation with temperature. Species that complete their life cycle in the Río de la Plata estuary, some of which are relevant to fisheries (64% of the analyzed species) were captured in the Solís Chico subestuary. The importance of this environment as a transitional system for some estuarine fish species is advised

Uso estuarial y composición de las especies de peces en el sub-estuario Solís Grande, Uruguay

A total of 1,298 fish representing estuarine, freshwater, marine migrants, anadromous and catadromous species were caught. Dominance of postlarvae and juveniles was observed. Mugil liza was the most abundant species. Jenynsia multidentata, Pogonias cromis and Cyprinus carpio were new records of species for the Solís Grande sub-estuary.Fueron capturados un total de 1.298 peces, representando especies estuariales, dulciacuícolas, marino migrantes, anádromas y catádromas. Fue observada una dominancia de post-larvas y juveniles. Mugil liza fue la especie más abundante. Jenynsia multidentata, Pogonias cromis y Cyprinus carpio fueron nuevos registros de especies en el subestuario Solís Grande

Reproducción, alimentación y crecimiento de urophycis brasiliensis (Kaup 1858) (Pisces Phycidae) en la costa uruguaya

Orientador: Eduardo Tarifeño.Tribunal: Dimitri Severov, Horacio Vera, Jorge P. Castello

Temporal dynamics of a fish community in the lower portion of a tidal creek, Pando sub-estuarine system, Uruguay

ABSTRACT Estuaries are highly dynamic ecosystems subjected to variability of their fish communities over different time scales. The nearshore fish community of the lower Pando estuary, a temperate sub-system of the Río de la Plata estuary, was sampled from May 2002 to June 2003. A total of 2,165 fishes, represented by 16 species were caught by seine netting. Captures were dominated by juveniles (>90%), as well as by the sciaenid Micropogonias furnieri (Desmarest, 1823) (82.8%). The fish community showed high seasonal variability, with the greatest diversity and biomass in summer and spring and the highest species richness during summer. Lowest values of all community parameters occurred in winter and autumn, seasons that presented the highest similarity in fish composition. Number of species was correlated with water temperature and salinity. The ichthyofaunal composition showed significant diel differences in summer and spring. Diel changes were observed in the density of M. furnieri and Odontesthes argentinensis (Valenciennes, 1835), occurring mainly during the day, and of Mugil liza Valenciennes, 1836, Parapimelodus valenciennis (Lütken, 1874) and Brevoortia aurea (Spix & Agassiz, 1829), caught mostly during the night. Temporal variability was attributed to environmental fluctuations, life cycle of species as well as to feeding patterns and small-scale displacements. Presented findings in the Pando sub-estuary denote similar juvenile use and seasonal patterns to those found in estuaries. Further studies in the nursery function and juvenile dynamics over the year are recommended in order to better understand the ecological role of sub-estuaries

Isolation and characterization of 18 microsatellites for Lycengraulis grossidens (Pisces: Clupeiformes)

Twelve polymorphic and six non-polymorphic microsatellite loci were isolated and characterized from a CT–GT enriched genomic library of Lycengraulis grossidens. The number of alleles ranged from 1 to 29. The observed and expected heterozygosity ranged from 0.19 to 0.8 and from 0.18 to 0.95, respectively. Cross-species amplification of the markers developed for L. grossidens was successful in the wild Engraulididae species Anchoa spinifer, Anchoa marinii, Anchoviella lepidentostole, Cetengraulis edentulous and Engraulis anchoita. The developed microsatellite loci are a potential powerful tool for studies of population genetics, genetic diversity and gene flow for these important food sources

Fish assemblage in a temperate estuary on the uruguayan coast: seasonal variation and environmental influence

The 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 uni- and 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.<br>Foi 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