Desarrollo larval de Etropus longimanus (Paralichthyidae) y Symphurus trewavasae (Cynoglossidae) en la costa Bonaerense, Argentina

The larval development of Etropus longimanus and Symphurus trewavasae (Pleuronectiformes) off the Buenos Aires coast was described. Both species have an elongated body; however, as the total length of Etropus longimanus larvae increased, their body became deeper. In Symphurus trewavasae the intestine was noticeably coiled. In E. longimanus the notochord flexion started at 3.9 mm and was completed at 5.0 mm standard length (SL). Vertebral formation began in larvae with a 4.6 mm SL and the definitive number of vertebrae (34-39) was observed in larvae of 4.8 mm SL. The dorsal fin had two elongated rays and the pelvic fins had only one. In Symphurus trewavasae the notochord flexion began at 5.9 mm and was completed at 8.0 mm SL. Migration of the right eye was completed in the metamorphic stage at 10.5 mm SL. Vertebral column ossification finished in flexion larvae of 6-7 mm SL, with a total number of 48-50 vertebrae. Four elongated rays of similar length were observed on the dorsal fin.Se describe el desarrollo larvario de Etropus longimanus y Symphurus trewavasae (Pleuronectiformes) que habitan la costa de Buenos Aires. El cuerpo de las larvas de ambas especies es alargado, pero en Etropus longimanus la altura del cuerpo se incrementa con el crecimiento. El tubo digestivo de Symphurus trewavasae es considerablemente enrollado. La flexión del urostilo en larvas de E. longimanus se inició cerca de los 3.9 mm y finalizó cerca de los 5 mm de longitud estándar (LS). Se observaron vértebras definidas en larvas de 4.6 mm LS y el número definitivo (34-39) se visualizó en individuos de 4.8 mm LS. Se distinguen dos radios largos al inicio de la aleta dorsal y uno en la pélvica. En Symphurus trewavasae la flexión del urostilo comenzó cerca de los 5.9 mm LS y finalizó aproximadamente a los 8.0 mm LS. La migración del ojo derecho hacia el lado izquierdo de la cabeza finalizó en el estadio de metamorfosis (10.5 mm LS). La osificación de la columna vertebral se completó en larvas entre los 6 y 7 mm LS, con un número total de 48-59 vértebras. Al inicio de la aleta dorsal se distinguen 4 radios largos con igual longitud

Transcriptomic differentiation underlying marine‐to‐freshwater transitions in the South American silversides Odontesthes argentinensis and O. bonariensis (Atheriniformes)

Salinity gradients are critical habitat determinants for freshwater organisms. Silverside fishes in the genus Odontesthes have recently and repeatedly transitioned from marine to freshwater habitats, overcoming a strong ecological barrier. Genomic and transcriptomic changes involved in this kind of transition are only known for a few model species. We present new data and analyses of gene expression and microbiome composition in the gills of two closely related silverside species, marine O. argentinensis and freshwater O. bonariensis and find more than three thousand transcripts differentially expressed, with osmoregulatory/ion transport genes and immune genes showing very different expression patterns across species. Interspecific differences also involve more than one thousand transcripts with nonsynonymous SNPs in the coding sequences, most of which were not differentially expressed. In addition to characterizing gill transcriptomes from wild‐caught marine and freshwater fishes, we test experimentally the response to salinity increases by O. bonariensis collected from freshwater habitats. Patterns of expression in gill transcriptomes of O. bonariensis exposed to high salinity do not resemble O. argentinensis mRNA expression, suggesting lack of plasticity for adaptation to marine conditions in this species. The diversity of functions associated with both the differentially expressed set of transcripts and those with sequence divergence plus marked microbiome differences suggest that multiple abiotic and biotic factors in marine and freshwater habitats are driving transcriptomic differences between these species

Spatial patterns of summer demersal fish assemblages around the Antarctic Peninsula and South Shetland Islands

During the research programme conducted on the OV Puerto Deseado in the summers of 2011 and 2013, 36 stations were sampled using a demersal net at depths between 53–590 m in the Antarctic Peninsula and South Shetland Islands. A total 3378 fish specimens belonging to 36 species were recorded. Notothenidae was the best-represented family in species number, with Lepidonotothen nudifrons, L. larseni and Trematomus scotti being the most numerous species. Of the fish assemblages, 20% of the species were considered as dominant, 10% as common, 13% as occasional and 57% as rare. Six groups (and two sub-groups) were obtained by the ordination diagram based on geographical location: group 1=Gerlache Strait, group 2=Deception Islands, group 3=Biscoe Island, group 4=between Elephant and King George islands, group 5=northern Antarctic Peninsula, and group 6=South Shetland Islands, with sub-groups 6a shallower South Shetland Islands and 6b deeper South Shetland Islands. Sampling depth and water temperature significantly explained the spatial pattern. A latitudinal pattern of decreasing abundance from north-east to south-west was found in L. larseni and the opposite in T. scotti. The predictability of fish composition in the assemblages’ areas could be a useful tool for ecosystem-based management.Fil: Llompart, Facundo Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Universidad Nacional de Tierra del Fuego; ArgentinaFil: Delpiani, Sergio Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Lattuca, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Delpiani, Gabriela Elina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Cruz Jiménez, Adriana Milena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Orlando, Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Ceballos, Santiago Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Universidad Nacional de Tierra del Fuego; ArgentinaFil: Diaz de Astarloa, Juan Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Vanella, Fabián Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Fernandez, Daniel Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Universidad Nacional de Tierra del Fuego; Argentin

Rafting seahorses: The presence of juvenile Hippocampus patagonicus in floating debris

A total of 477 juvenile Hippocampus patagonicus recorded in 80 sampling events were detected rafting on the surface during high tide at San Antonio Bay, northern Patagonia, Argentina. If rafting juveniles drift long distances beyond their original populations, they have the potential to form new populations, which may explain the wide distribution of H. patagonicus.Fil: Luzzatto, Diego. Universidad Nacional del Comahue. Instituto de Biologia Marina y Pesquera Almirante Storni; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Estalles, María Lourdes. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Comahue. Instituto de Biologia Marina y Pesquera Almirante Storni; ArgentinaFil: Diaz de Astarloa, Juan Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras; Argentin

Composition and Relative Abundance of Fish Species in Two Coastal Lagoons in Austral South America: Peixe Lagoon (31ºS; 51ºW), Brazil, and Mar Chiquita Lagoon (37ºS; 57ºW), Argentina

This article describes and compares the shallow water fish-fauna from two coastal lagoons (Peixe Lagoon, in Brazil, and Mar Chiquita Lagoon, in Argentina). Peixe Lagoon was sampled between 2000 and 2001 using a 9 m beach seine net (12 mm bar mesh in the wings and 5 mm in the centre 3 m section) totalizing 125 samples, which yielded 33,848 individuals and 32 species. Mar Chiquita Lagoon was sampled from 1995 to 1998 using a 21) m beach seine net (12 mm bar mesh) totalizing 232 samples resulting in 31,097 individuals of 28 species. A total of 47 species were observed in both lagoons and 13 were shared. The "marine-estuarine-related" species were similar and dominate the fish assemblages in both lagoons. The remaining species were similar to the species collected along the southern Brazil, Uruguay and Argentina estuaries. The number of species observed in Peixe Lagoon (S = 32) was higher than in Mar Chiquita Lagoon (S = 28) and is probably associated with a strong latitudinal gradient of species richness increasing from north to south. Considering that the Peixe Lagoon and Mar Chiquita Lagoon are isolated by the large estuaries of Patos Lagoon and Prata River, the composition of the species with low abundance and occasional occurrence were different for each local studied. These results expand the knowledge for the fauna of both sites and help conservation and management from both lagoons.Este artigo descreve e compara a ictiofauna de zonas rasas de duas lagunas costeiras (lagoa do Peixe, no Brasil e laguna Mar Chiquita, na Argentina). A lagoa do Peixe foi amostrada entre 2000 e 2001 com rede de arrasto de praia (9 m de comprimento, malha de 5 mm entre nós 3 m centrais e de 12 mm na lateral) totalizando 125 amostras, resultando na coleta de 33.848 indivíduos e 32 espécies. A laguna de Mar Chiquita, foi amostrada durante os anos de 1995 e 1998 com rede de arrasto de praia (20 m de comprimento, com panagem única de 12 mm), totalizando 232 amostras, sendo coletados 31.097 indivíduos pertencentes a 28 espécies. Das 47 espécies observadas, 13 são comuns nos dois sistemas. As espécies marinhas-estuarino-relacionadas foram semelhantes e dominaram as assembléias de peixes em ambas as lagunas. As espécies restantes foram similares às espécies coletadas nos estuários do sul do Brasil, Uruguai e Argentina. O número de espécies observado na lagoa do Peixe (S = 32) foi maior que em Mar Chiquita (S = 28), provavelmente associado a um forte gradiente latitudinal negativo de riqueza de espécies de norte para sul. Pelo fato da lagoa do Peixe e da laguna Mar Chiquita estarem isoladas pelos grandes estuários da lagoa dos Patos e do rio da Prata, a composição das espécies de baixa abundância e a ocorrência ocasional foram bem distintas para cada local estudado. Esses resultados ampliam o conhecimento da fauna de ambos locais e ajudam na conservação e manejo de ambas as lagunas

Composição e abundância da ictiofauna de duas lagunas costeiras da América do Sul Austral: lagoa do Peixe (31ºS; 51ºW), Brasil e laguna Mar Chiquita (37ºS; 57ºW), Argentina

This article describes and compares the shallow water fish-fauna from two coastal lagoons (Peixe Lagoon, in Brazil, and Mar Chiquita Lagoon, in Argentina). Peixe Lagoon was sampled between 2000 and 2001 using a 9 m beach seine net (12 mm bar mesh in the wings and 5 mm in the centre 3 m section) totalizing 125 samples, which yielded 33,848 individuals and 32 species. Mar Chiquita Lagoon was sampled from 1995 to 1998 using a 21) m beach seine net (12 mm bar mesh) totalizing 232 samples resulting in 31,097 individuals of 28 species. A total of 47 species were observed in both lagoons and 13 were shared. The "marine-estuarine-related" species were similar and dominate the fish assemblages in both lagoons. The remaining species were similar to the species collected along the southern Brazil, Uruguay and Argentina estuaries. The number of species observed in Peixe Lagoon (S = 32) was higher than in Mar Chiquita Lagoon (S = 28) and is probably associated with a strong latitudinal gradient of species richness increasing from north to south. Considering that the Peixe Lagoon and Mar Chiquita Lagoon are isolated by the large estuaries of Patos Lagoon and Prata River, the composition of the species with low abundance and occasional occurrence were different for each local studied. These results expand the knowledge for the fauna of both sites and help conservation and management from both lagoons.Este artigo descreve e compara a ictiofauna de zonas rasas de duas lagunas costeiras (lagoa do Peixe, no Brasil e laguna Mar Chiquita, na Argentina). A lagoa do Peixe foi amostrada entre 2000 e 2001 com rede de arrasto de praia (9 m de comprimento, malha de 5 mm entre nós 3 m centrais e de 12 mm na lateral) totalizando 125 amostras, resultando na coleta de 33.848 indivíduos e 32 espécies. A laguna de Mar Chiquita, foi amostrada durante os anos de 1995 e 1998 com rede de arrasto de praia (20 m de comprimento, com panagem única de 12 mm), totalizando 232 amostras, sendo coletados 31.097 indivíduos pertencentes a 28 espécies. Das 47 espécies observadas, 13 são comuns nos dois sistemas. As espécies marinhas-estuarino-relacionadas foram semelhantes e dominaram as assembléias de peixes em ambas as lagunas. As espécies restantes foram similares às espécies coletadas nos estuários do sul do Brasil, Uruguai e Argentina. O número de espécies observado na lagoa do Peixe (S = 32) foi maior que em Mar Chiquita (S = 28), provavelmente associado a um forte gradiente latitudinal negativo de riqueza de espécies de norte para sul. Pelo fato da lagoa do Peixe e da laguna Mar Chiquita estarem isoladas pelos grandes estuários da lagoa dos Patos e do rio da Prata, a composição das espécies de baixa abundância e a ocorrência ocasional foram bem distintas para cada local estudado. Esses resultados ampliam o conhecimento da fauna de ambos locais e ajudam na conservação e manejo de ambas as lagunas