Holocene occupation history of pygoscelid penguins at Stranger Point, King George (25 de Mayo) Island, northern Antarctic Peninsula

We report additional fossil evidence for pygoscelid penguins breeding on King George (25 de Mayo) Island, South Shetland Islands, in the Holocene beginning at ~7000 cal. yr BP. This evidence comes from a raised marine beach deposit formerly studied and described as Pingfo I at Stranger Point, Potter Peninsula. We relocated and exposed deposits at this site and recovered additional samples of penguin bones from five stratigraphic beds that are redescribed here. Most of these bones are from juvenile penguins and exhibit little or no wear indicating minimal transport to the beach deposits. Some of the bones are developed enough to be identifiable to Adélie (Pygoscelis adeliae), Gentoo (Pygoscelis papua), and Chinstrap (Pygoscelis antarctica) penguins, indicating that all three species were breeding at Stranger Point from ~7320 to 4865 cal. yr BP. This breeding occupation corresponds with the first warming and deglaciation that occurred in the northern Antarctic Peninsula by this time and ends with the onset of reglaciation of the Peninsula. At least 31 abandoned penguin mounds and ornithogenic soils also were located and sampled at Stranger Point and indicate that the current occupation of this area by all three pygoscelid penguins dates no older than ~535 cal. yr BP. The absence of ornithogenic soils from earlier Holocene breeding was probably due to glacial activity and soil solifluction during periods of warming in the mid to late Holocene.Fil: Emslie, Steven Douglas. University of North Carolina; Estados UnidosFil: Romero, Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Juares, Mariana Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Argota, Martin R.. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentin

Stable isotope analysis of multiple tissues from chick carcassess of three pygoscelid penguins in Antarctica

Varios tipos de tejidos animales son empleados para el análisis de isótopos estables, considerando el período de tiempo que cada tejido refleja y dependiendo de su disponibilidad para colección. Aquí, hemos investigado los valores isotópicos (δ13C y δ15N) de cuatro tejidos (pluma, piel, uña y hueso) colectados de cadáveres de pichones de las tres especies de pingüinos pigoscélidos con el objetivo de comparar precisión y variabilidad de la información obtenida. Las muestras fueron colectadas en la Isla 25 de Mayo/King George durante el verano austral 2017/18. Los cadáveres de pichones son comúnmente encontrados alrededor de colonias activas y el muestreo oportunista puede fácilmente ser realizado minimizando el disturbio en la colonia. Un total de 25–36 cadáveres por especie fueron muestreados en colonias de Pingüinos Adelia Pygoscelis adeliae, Pingüinos Papúa P. papua, y Pingüinos Barbijo P. antarcticus. Un modelo lineal mixto mostró que los valores de δ13C variaron dependiendo del tejido presumiblemente debido a la discriminación isotópica específica a cada uno de ellos. En cambio, el único tejido significativamente diferente para δ15N fue la uña. La información reveló diferencias dietarias entre especies, exhibiendo el Pingüino Papúa los valores más altos. Asimismo, los Pingüinos Barbijo mostraron valores más altos de δ13C que los Pingüinos Adelia, aunque esta diferencia no fue significativa. Los Papúa mostraron la mayor variabilidad para todos los tejidos. La piel exhibió la mayor variabilidad en las tres especies y fue el tejido menos confiable para análisis de isótopos estables; mientras que las uñas mostraron la menor variabilidad. Los valores obtenidos de dos huesos distintos (tibiatarso y coracoides) no mostraron diferencias significativas, indicando que el muestreo de otros huesos probablemente resultará en valores similares. Nuestros resultados brindan información para poder estimar la composición de la dieta con precisión y comparar diferentes especies y/o colonias abandonadas y activas mediante el muestreo oportunista.Many types of animal tissues are increasingly being used for stable isotope analysis, with their application dependent on the time frame they reflect and their availability for collection. Here, we investigated the isotopic values (δ13C and δ15N) of four tissues (feather, skin, toenail, and bone) collected from fledgling-period chick carcasses of three species of pygoscelid penguins to compare the variability and accuracy of the data among tissues. Samples were collected at 25 de Mayo/King George Island during the 2017/18 austral summer. Chick carcasses are commonly found at active penguin colonies, and “opportunistic sampling” can easily be performed without disturbing nesting penguins. A total of 25-36 carcasses per species were sampled at active colonies of Adélie Pygoscelis adeliae, Gentoo P. papua, and Chinstrap P. antarcticus penguins. A linear mixed model showed that δ13C values varied significantly between tissues, presumably due to tissue-specific isotopic discrimination. In contrast, the only tissue with significantly different δ15N values was toenail. Stable isotope data revealed dietary differences among species, with Gentoo Penguins having higher average isotopic values in tissues compared to Adélie and Chinstrap penguins. In addition, Chinstrap Penguins showed a consistent, but not statistically significant, trend in having higher δ13C values compared to Adélie Penguins. Gentoo Penguins displayed the highest isotopic variability of any species for all tissues. Isotopic composition was most variable in skin in all three species making skin the least reliable tissue for isotope analysis, whereas isotopic values were least variable in toenails. Comparison of isotopic values between two bones (tibiotarsus and coracoid) showed no significant differences in isotopic values, indicating that when the same bone is not available for sampling from carcasses, sampling of any major skeletal element is likely to provide a meaningful comparison. These results allow for more informed opportunistic sampling to accurately estimate and compare penguin diet among species and between ancient and active colonies.Fil: Ciriani, Yanina Anabella. University of North Carolina; Estados UnidosFil: Juares, Mariana Alejandra. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Santos, Maria Mercedes. Ministerio de Relaciones Exteriores, Comercio Internacional y Culto. Direccion Nacional del Antártico; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Emslie, Steven Douglas. University of North Carolina; Estados Unido

"Ino" colour aberration in gentoo penguin (Pygoscelis papua) in Antarctica

Two main types of pigments, carotenoids and melanin, primarily determine plumage colouration in birds. Carotenoids are obtained from food, while melanin formation involves metabolic processes and is genetically determined. Melanin pigments comprise pheomelanin (red/brown) and eumelanin (brown/black). Any change in the formation processes of these types of pigments may lead to abnormal colouration of an individual For example, a strong qualitative reduction of both types of melanin defines a colour mutation called "ino". On 15 Dec 2003, an ino chick of a gentoo penguin (Pygoscelis papua); was observed at Stranger Point, 25 de Mayo/King George I, South Shetland (62° 16´ S, 58° 37´ W). The following year, on 5 Dec 2004, an ino prebreeder gentoo penguin was seen at the same locality. During 2006/07 breeding season an ino adult of the same species successfully reared 2 normally coloured chicks. The ino penguin we observed showed pale brown colour in the normally dark areas of the plumage in this species. It had reddish eyes and grey claws. The beak remained orange but the normally dark culmen was grey. In summary, the ino penguin showed a clear reduction of the darkest areas of the body changing from black to pale brown in plumage and from black to grey in other tissues such as beak and claws. Nevertheless, the distinctive colour pattern of a gentoo penguin was still recognisable. To our knowledge this is the 1st report of an ino gentoo penguin, following van Grouwes (2006) classification.Fil: Juares, Mariana Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Negrete, Javier. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Mennucci, Jorge Augusto. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Longarzo, Mria Lucrecia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Coria, Néstor Rubén. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentin

Coastal regions of the northern Antarctic Peninsula are key for gentoo populations

Southern Ocean ecosystems are rapidly changing due to climate variability. An apparent beneficiary of such change in the western Antarctic Peninsula (WAP) is the gentoo penguin Pygoscelis papua, which has increased its population size and expanded its range southward in the last 20 years. To better understand how this species has responded to large-scale changes, we tracked individuals during the non-breeding winter period from five colonies across the latitudinal range of breeding sites in the WAP, including from a recently established colony. Results highlight latitudinal gradients in movement; strong associations with shallow, coastal habitats along the entire Antarctic Peninsula; and movements that are independent of, yet constrained by, sea ice. It is clear that coastal habitats essential to gentoo penguins during the breeding season are similarly critical during winter. Larger movements of birds from northern colonies in the WAP further suggest that leap-frog migration may influence colonization events by facilitating nest-area prospecting and use of new haul-out sites. Our results support efforts to develop a marine protected area around the WAP. Winter habitats used by gentoo penguins outline high priority areas for improving the management of the spatio-temporally concentrated krill (Euphausia superba) fishery that operates in this region during winter.Fil: Korczak Abshire, Malgorzata. Polish Academy of Sciences; ArgentinaFil: Hinke, Jefferson T.. National Ocean And Atmospheric Administration; Estados UnidosFil: Milinevsky, Gennadi. National Antarctic Scientific Center of Ukraine; Ucrania. National University of Kyiv; UcraniaFil: Juares, Mariana Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Relaciones Exteriores y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino. Departamento de Biología de Predadores Tope; ArgentinaFil: Watters, George M.. National Ocean And Atmospheric Administration; Estados Unido

"Ino" colour aberration in gentoo penguin (Pygoscelis papua) in Antarctica

Two main types of pigments, carotenoids and melanin, primarily determine plumage colouration in birds. Carotenoids are obtained from food, while melanin formation involves metabolic processes and is genetically determined. Melanin pigments comprise pheomelanin (red/brown) and eumelanin (brown/black). Any change in the formation processes of these types of pigments may lead to abnormal colouration of an individual For example, a strong qualitative reduction of both types of melanin defines a colour mutation called "ino". On 15 Dec 2003, an ino chick of a gentoo penguin (Pygoscelis papua); was observed at Stranger Point, 25 de Mayo/King George I, South Shetland (62° 16´ S, 58° 37´ W). The following year, on 5 Dec 2004, an ino prebreeder gentoo penguin was seen at the same locality. During 2006/07 breeding season an ino adult of the same species successfully reared 2 normally coloured chicks. The ino penguin we observed showed pale brown colour in the normally dark areas of the plumage in this species. It had reddish eyes and grey claws. The beak remained orange but the normally dark culmen was grey. In summary, the ino penguin showed a clear reduction of the darkest areas of the body changing from black to pale brown in plumage and from black to grey in other tissues such as beak and claws. Nevertheless, the distinctive colour pattern of a gentoo penguin was still recognisable. To our knowledge this is the 1st report of an ino gentoo penguin, following van Grouwes (2006) classification.Fil: Juares, Mariana Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Negrete, Javier. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Mennucci, Jorge Augusto. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Longarzo, Mria Lucrecia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Coria, Néstor Rubén. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentin

Relato de deformidade no bico de um ninhego do pinguim-gentoo Pygoscelis papua (Spheniscidae)

Neste artigo reportamos sobre um filhote de pinguim-gentoo com uma deformidade na maxila, encontrado numa colônia das ilhas Shetland do sul. Embora a prevalência deste tipo de anomalia esteja aumentando, as razões para sua explicação não são tão simples de determinar. Contudo, como uma das causas conhecidas de indução à anomalias de formação á a deterioração de condições ambientais, consideramos importantes relatos como o feito nesta publicação.Fil: Juares, Mariana Alejandra. Ministerio de Relaciones Exteriores y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino. Departamento de Biología de Predadores Tope; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Santos, Maria Mercedes. Ministerio de Relaciones Exteriores y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino. Departamento de Biología de Predadores Tope; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mennucci, Jorge Augusto. Ministerio de Relaciones Exteriores y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino. Departamento de Biología de Predadores Tope; ArgentinaFil: Longarzo, Mria Lucrecia. Ministerio de Relaciones Exteriores y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino. Departamento de Biología de Predadores Tope; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Coria, Néstor Rubén. Ministerio de Relaciones Exteriores y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino. Departamento de Biología de Predadores Tope; Argentin

Relato de deformidade no bico de um ninhego do pinguim-gentoo Pygoscelis papua (Spheniscidae)

Neste artigo reportamos sobre um filhote de pinguim-gentoo com uma deformidade na maxila, encontrado numa colônia das ilhas Shetland do sul. Embora a prevalência deste tipo de anomalia esteja aumentando, as razões para sua explicação não são tão simples de determinar. Contudo, como uma das causas conhecidas de indução à anomalias de formação á a deterioração de condições ambientais, consideramos importantes relatos como o feito nesta publicação.Fil: Juares, Mariana Alejandra. Ministerio de Relaciones Exteriores y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino. Departamento de Biología de Predadores Tope; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Santos, Maria Mercedes. Ministerio de Relaciones Exteriores y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino. Departamento de Biología de Predadores Tope; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mennucci, Jorge Augusto. Ministerio de Relaciones Exteriores y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino. Departamento de Biología de Predadores Tope; ArgentinaFil: Longarzo, Mria Lucrecia. Ministerio de Relaciones Exteriores y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino. Departamento de Biología de Predadores Tope; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Coria, Néstor Rubén. Ministerio de Relaciones Exteriores y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino. Departamento de Biología de Predadores Tope; Argentin

Birds at Laurie Island, South Orkney Islands, Antarctica: Breeding species and their distribution

Bird communities of the ice-free areas of Laurie Island were surveyed during the breeding seasons of 1993/94 and 1994/95. Additional censuses of penguin colonies were made during the 2004/05 season. Twenty-nine seabird species were recorded, of which 15 were breeding. Adélie Penguins Pygoscelis adeliae bred at six localities, primarily on the south coast. This survey showed that the population of Adélie Penguins in the 2004/05 season was 32.3% lower than that found a previous study conducted during the 1983/84 season. Chinstrap Penguins Pygoscelis antarctica are the most numerous pygoscelid penguins in the area. Previous studies showed they had increased between 1948 and 1983 at many colonies. Since then, there was a slight increase in the population between 1983/84 and 1994/95 (from 141 950 to 143 792 breeding pairs, +1.3%). However, populations of Chinstrap Penguins in the Antarctic Peninsula showed different trends in the late 1980s. Because the censuses available from Laurie Island after 1994/95 season were incomplete, it is not possible to draw any conclusions about Chinstrap Penguin population trends. Population size and distribution of several other species breeding in the area are updated, and possible factors affecting short-term changes are discussed.Fil: Coria, Néstor Rubén. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Montalti, Diego. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rombola, Emilce Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Santos, Maria Mercedes. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Garcia Betoño, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Juares, Mariana Alejandra. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

The diet of the Antarctic fur seal Arctocephalus gazella at the South Orkney Islands in ten consecutive years

To improve the knowledge on the Antarctic fur seal foraging behavior, evaluate whether changes in its diet are associated with changes in prey availability, and evaluate whether fisheries had negative impacts on Antarctic fur seal populations, a total of 1359 scats of non-breeding males were collected in ten consecutive sampling periods between 1994 and 2003 at Laurie Island, South Orkney Islands. Antarctic krill was the most numerous prey throughout the sampling period followed in importance by fish prey. Antarctic krill also predominated by reconstructed mass, except during 1994 and 1998 when penguins were the most important prey, and during 1995 when fish dominated. Among fish, demersal-benthic species (mainly Gobionotothen gibberifrons, Chaenocephalus aceratus and Chionodraco rastrospinosus) dominated the diet except in 1997, 1998, 1999 and 2002 when myctophids (mainly Gymnoscopelus nicholsi and Electrona antarctica) were the most important fish prey. In seasons when fish dominated the diet, the diet was primarily comprised of demersal species. Although our results are in overall agreement with previous studies, the contribution to the diet of the main preys changed throughout the sampling period, probably in parallel with changes in prey abundance. According to historical results on fish consumption, the fisheries carried out in the past have had negative impacts on seal populations from the South Orkney Islands.Fil: Casaux, Ricardo Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Centro de Investigación Esquel de Montaña y Estepa Patagóica. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales - Sede Esquel. Centro de Investigación Esquel de Montaña y Estepa Patagónica; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Juares, Mariana Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Carlini, Alejandro. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Corbalán, Aldo. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentin

Diet composition and foraging habitats of Adélie and gentoo penguins in three different stages of their annual cycle

We evaluated the diet of Adélie (Pygoscelis adeliae) and gentoo (P. papua) penguins at Stranger Point colony (25 de Mayo/King George Island) during different stages of their annual cycle using the stable isotope method and the conventional dietary analyses (i.e. stomach contents). Antarctic krill (Euphausia superba) dominated the diet of Adélie and gentoo penguins in all three studied stages (pre-breeding, breeding and post-breeding). Nevertheless, only in gentoo penguins a shift in the diet was evident from mainly krill during the breeding stage to mixed diet (i.e. krill and fish/squids) during the pre- and post-breeding stages. Results from stable isotopes suggest that Adélie penguins might be foraging in southern localities compared to their congener during the inter-breeding period. Moreover, Adélie penguins showed a large individual variability in foraging habitat during the post-breeding stage. However, our model has predicted that both species exploited similar areas during the breeding season. The results obtained during the chick-rearing stage were compared with the stomach contents of both species obtained during the same season (2011/2012). Our findings provide new knowledge on the feeding ecology and foraging habitats of pygoscelid penguins. They confirm the importance of Antarctic krill during the annual cycle and improve the understanding of life strategies and predator–prey interactions essentially out of the reproductive period, in which the information is very limited. These results can help to establish new management strategies, particularly considering the potential overlap between predators and fisheries.Fil: Juares, Mariana Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Santos, Maria Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Mennucci, Jorge A.. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Coria, Néstor Rubén. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Mariano y Jelicich, Rocío. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin