A new mass stranding of false killer whale, Pseudorca crassidens, in the Strait of Magellan, Chile

We report the mass stranding of 46 false killer whales in the Strait of Magellan in February 2013. We present observation-based information about body size, sex, dental formula and necropsies. Sexual dimorphism in body length was clear, with males being significantly larger than females. Dental formula coincided with previous reports for the species, with asymmetry present in females. Individuals showed normal body conditions without any signs of apparent disease. The cause of the stranding remains unknown, however the coastal morphology hypothesis is a possible explanation.Fil: Haro, Daniela. Universidad de Chile; ChileFil: Aguayo Lobo, Anelio. Instituto Antártico Chileno; ChileFil: Blank, Olivia. Clínica Veterinaria Timaukel; ChileFil: Cifuentes, Constanza. Universidad Mayor; ChileFil: Dougnac, Catherine. Universidad de Chile; ChileFil: Arredondo, Cristóbal. Universidad de Chile; ChileFil: Pardo, Catalina. Universidad de Chile; ChileFil: Cáceres Saez, Iris. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentin

Macro-elements K, Na, Cl, Mg, and Ca in body tissues of false killer whales (Pseudorca crassidens) from the Southern Ocean

Macro-elements such as potassium (K), sodium (Na), chlorine (Cl), magnesium (Mg), and calcium (Ca) are essential in marine mammals’ nutrition. These elements are involved in physiological processes. Upon consumption, they are assimilated and accumulate in tissues. For the first time, they were detected in lung, spleen, liver, kidney, muscle, uterus, ovary, and testis of 5, and in skin of 12, stranded false killer whales (Pseudorca crassidens) in sub-Antarctic waters of the South Atlantic Ocean. Results showed that testis reached the highest potassium mean concentration, 1.62 (0.25) wt% dry weight (DW) (standard deviation in parentheses), followed by muscle, 1.11 (0.12) wt% DW, and decreasing in skin to 0.351 (0.098) wt% DW. Testis and lung exhibited among the highest sodium concentrations, with 0.96 (0.20) and 0.93 (0.18) wt% DW, respectively. Chlorine concentration was highest in testis, (1.55 wt% DW) followed by uterus (1.26 wt% DW) and kidney [1.13 (0.16) wt% DW]. Magnesium reached higher concentrations in uterus (0.134 wt% DW) and muscle [0.109 (0.054) wt% DW]. Calcium was higher in lung [0.230 (0.05) wt% DW] and kidney (0.149; 0.294 wt% DW). Hepatic levels of K, Na, Cl, and Mg in false killer whales are generally within the range of other studied species, while Ca levels are the highest reported. Macro-element concentration ranges were established for diverse tissues and organs of the false killer whale as the current best available baseline reference values for assessments of general condition.Fil: Cáceres Saez, Iris. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Haro, Daniela. Universidad Santo Tomás (ust);Fil: Blank, Olivia. No especifíca;Fil: Aguayo Lobo, Anelio. No especifíca;Fil: Dougnac, Catherine. Wildlife Conservation Society; ChileFil: Arredondo, Cristóbal. Wildlife Conservation Society; ChileFil: Cappozzo, Humberto Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Ribeiro, Sergio. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentin

Cetáceos bioindicadores de metales pesados: Los cetáceos son animales longevos y depredadores tope de las redes alimen-tarias marinas, así resultan expuestos a las máximas concentraciones de con-taminantes ambientales. El estado de sus poblaciones es un buen indicador de calidad del mar.

Hoy en día, la ecotoxicología avanza en el estudio sobre la contaminación e interacción con la biota; su relevancia le permite al ser humano evaluar y conocer las acciones y los efectos de la contaminación sobre los seres vivos en nuestro planeta. Algunos organismos son apropiados bioindicadores, centinelas o monitores del estado de salud los ecosistemas. En el caso particular del ambiente marino, los cetáceos por su posición tope en las redes tróficas y su longevidad, se encuentran ex-puestos a la acumulación de metales pesados a través del alimento. De tal forma, estos organismos resultan apropiados bioindicadores de los ecosistemas marinos

Calculating effective growth rate from a random Leslie model: Application to incidental mortality analysis

Demographic models are commonly used to study cetacean population dynamics and are characterized by a wide range of age classes. The primary building blocks are age-specific survival or mortality and birth rates, which can be combined using a Leslie matrix protocol to provide estimates of maximum possible rates of increase for population size. In this context, specific mortality data are valuable for modeling the viability of threatened species. Depletion of prey, pollution, and other anthropogenic disturbances are believed to have contributed to the decline of populations, but the evidence is less conclusive for these factors than for bycatch. In an attempt to estimate a population growth rate that incorporates uncertainties in vital parameters, we apply a random Leslie analysis to calculate effective growth rate for the time-dependent mean-value population. Here we provide the algorithm to implement it for a general 13×13 random survival model. An effective growth rate can be characterized by studying the time evolution of the mean-value population vector state (in an age-structured description). We show that the asymptotic behavior of the mean-value vector state, which characterizes the population growth rate when the model has random vital parameters, exhibits a value that is below previously expected potential estimations. We demonstrate the procedure using bibliographic revision data of the harbor porpoise (Phocoena phocoena) in Canadian waters, subjected to incidental mortality.Fil: Caceres Garcia Faure, Manuel Osvaldo. Universidad Nacional de Cuyo; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Area de Energía Nuclear. Instituto Balseiro; ArgentinaFil: Cáceres Saez, Iris. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales; Argentina. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche; Argentin

Mercury and Selenium in Subantarctic Commerson's dolphins (Cephalorhynchus c. commersonii).

Total mercury (THg) and selenium (Se) concentrations were determined in hepatic, renal, and muscle tissues of seven specimens of Commerson´s dolphins incidentally captured in artisanal fisheries of Tierra del Fuego, Argentina, by instrumental neutron activation analysis. Liver yielded the mean highest concentration of THg 9.40 (9.92) μg g(-1) dry weight (DW) (standard deviation of the average in parenthesis); kidney and muscle showed similar values, ranging from 2.34 to 3.63 μg g(-1) DW. Selenium concentrations were similar in hepatic and renal tissues, with values from 13.62 to 14.56 μg g(-1) DW; the lowest concentration was observed in muscle, 4.13 (2.05) μg g(-1) DW. Among the specimens analyzed, the maximum concentrations of THg and Se were observed in the single adult female studied. An increasing age trend is observed for THg concentrations in tissues analyzed. The molar ratio of Se/Hg in the hepatic, renal, and muscle tissues were 8.7 (9.6), 13.2 (9.5), and 9.0 (11.4), respectively, suggesting Se protection against Hg toxicity. Silver concentrations in the three tissues were included, and the Se/(Hg + 0.5×Ag) molar ratio showed values closer to 1. Both Hg and Se concentrations in liver and kidney were comparable to those found in other small odontocetes from Argentine and Brazilian waters. This study constitutes the first joint description reported of Hg and Se concentrations in liver, kidney, and muscle of the Commerson´s dolphin species.Fil: Cáceres Saez, Iris. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales; ArgentinaFil: Dellabianca, Natalia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Goodall, R. Natalie P.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Cappozzo, Humberto Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales; ArgentinaFil: Ribeiro Guevara, Sergio. Comision Nacional de Energia Atomica. Gerencia D/area de Energia Nuclear. Unidad de Actividad de Ingenieria Nuclear. Laboratorio de Analisis Por Activacion Neutronica; Argentin

Heavy metals and essential elements in Commerson's dolphins (Cephalorhynchus c. commersonii) from the southwestern South Atlantic Ocean

A survey of the elemental contents of K, Mg, Mn, Na, Cl, Br, Cs, Co, Rb, Fe, Zn, Al, Ti, V, As, Ag, Au and Cd in liver, kidney and muscle was performed in specimens of Commerson's dolphins (Cephalorhynchus c. commersonii) from subantarctic waters. The concentrations were determined by Instrumental Neutron Activation Analysis and the specimens derives from animals incidentally caught in artisanal fishing nets. Liver had the highest concentrations of Fe, 897(79) μg g-1 DW (dry weight) (average; standard deviation in parenthesis), kidney had the highest Cd, 35 (24) μg g-1 DW; Cl, 9,200 (1,700) μg g-1 DW; Na, 6,800 (1,100) μg g-1 DW and Br, 73(12) μg g-1 DW; and muscle the highest Mg 954 (71) μg g-1 DW. Potassium and Cs concentrations in muscle and kidney ranged in 12,510-13,020 and 0.230-0.252 μg g-1 DW, respectively; Zn and Mn concentrations were similar in liver and kidney (117-122.1 and 3.66-16.5 μg g-1 DW, respectively). Silver was high in liver 5.4(5.0) μg g-1 DW and kidney 1.2(2.7) μg g-1 DW. Gold, Rb, Co and As had no differences among tissues. Likewise, as in other odontocete species, the concentrations of essential elements showed little variation between the specimens analyzed, since they are regulated biochemically; however, heavy metals showed high variability. This study constitutes the first large description of the elemental composition in Commerson's dolphins from subantarctic waters of the South Atlantic Ocean.Fil: Cáceres Saez, Iris. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; ArgentinaFil: Ribeiro Guevara, Sergio. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Unidad de Actividad de Ingeniería Nuclear. Laboratorio de Análisis por Activación Neutrónica; ArgentinaFil: Dellabianca, Natalia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Prosser Goodall, Rae Natalie. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Cappozzo, Humberto Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentin

High status of mercury and selenium in false killer whales (Pseudorca crassidens, Owen 1846) stranded on Southern South America: A possible toxicological concern?

The study was carried out to determine Hg and Se concentrations in false killer whales stranded on the Estrecho de Magallanes, Chile, South America. Tissue samples of five mature specimens were analyzed (two females and three males). Mean Hg concentration in liver 1068 (234) μg g−1 dry weight (DW) (standard deviation in parenthesis) was markedly higher than those in kidney 272 (152) μg g−1 DW, lung 423 (325) μg g−1 DW, spleen 725 (696) μg g−1 DW, muscle 118 (94) μg g−1 DW and testicle 18.0 (2.8) μg g−1 DW. Mean Se concentration in liver, 398 (75) μg g−1 DW, was higher than those in kidney 162 (69) μg g−1 DW, lung 128 (84) μg g−1 DW, spleen 268 (245) μg g−1 DW, muscle 47 (38) μg g−1 DW and testicle 25.4 (2.1) μg g−1 DW. Positive correlations were found between Hg and Se molar concentrations in muscle, lung, spleen and kidney. Molar ratio of Se/Hg in liver, lung and muscle were 1 suggesting a Se protection against Hg toxicity. In all the examined specimens Hg values exceeded the toxic thresholds defined for hepatic damage in marine mammals, with Se/Hg molar ratios below 1 implying limited protective action of Se. Generally, our results showed that individuals are carrying a significant burden, reflecting a high exposure to this toxic metal. This constitutes the first report on Hg and Se levels for a large subantarctic odontocete in South America region, providing insights into their contamination status and with information to the understanding of possible impacts on wild populations.Fil: Cáceres Saez, Iris. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; ArgentinaFil: Haro, Daniela. Universidad de Chile; Chile. Universidad Santo Tomas; ChileFil: Blank, Olivia. Clínica Veterinaria Timaukel; Chile. Centro de Rehabilitación de Aves Leñadura ; ChileFil: Aguayo Lobo, Anelio. Instituto Antártico Chileno; ChileFil: Dougnac, Catherine. Universidad de Chile; ChileFil: Arredondo, Cristóbal. Universidad de Chile; ChileFil: Cappozzo, Humberto Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; ArgentinaFil: Ribeiro, Sergio. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Unidad de Actividad de Ingeniería Nuclear. Laboratorio de Análisis por Activación Neutrónica; Argentin

Assessing the growth rate of endangered Franciscana dolphin in Argentina, South America

Cetacean populations are vulnerable to decline due to anthropogenic threats and life history traits. The Franciscana dolphin (Pontoporia blainvillei) has been considered the most affected small dolphin in the Southwestern Atlantic Ocean. In this study a method is presented for estimating the growth rate of the Franciscana dolphin affected by incidental mortality (bycatch) in coastal marine areas of Argentina, South America. We used a general approach based on vital parameters information such as reproductive rates and survival probabilities for an age-structured population. The Franciscana’s growth rate was estimated using Leslie’s approach through an algorithm implemented in a 14 14 matrix model. Then, the population was characterized analysing the discrete-time evolution of the age–population vector. We found that the potential growth rate <1 indicates that Franciscanas in Argentina are susceptible to decline under current levels of incidental mortality.Fil: Caceres Garcia Faure, Manuel Osvaldo. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Universidad Nacional de Cuyo; ArgentinaFil: Cáceres Saez, Iris. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Secchi, Eduardo Resende. Universidade Federal Do Rio Grande; BrasilFil: Negri, Maria Fernanda. Universidad Nacional de Tierra del Fuego, Antartida E Islas del Atlantico Sur. Centro de Investigaciones y Transferencia Tierra del Fuego. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro de Investigaciones y Transferencia Tierra del Fuego. - Gobierno de la Provincia de Tierra del Fuego. Centro de Investigaciones y Transferencia Tierra del Fuego.; ArgentinaFil: Panebianco, María Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Cappozzo, Humberto Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentin

Sexual dimorphism and morphometric relationships in pelvic bones of Commerson's dolphins (Cephalorhynchus c. commersonii) from Tierra del Fuego, Argentina

The hydrodynamic shape of the cetacean body and the reduction of the pelvic girdle leading to the loss of the pelvic limbs are the result of evolutionary adaptations to aquatic life; these changes are clearly represented in fossil remains (Thewissen et al. 2009)Fil: Cáceres Saez, Iris. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales; Argentina. Museo Acatush un de Aves y Mamiferos Marinos Australes; ArgentinaFil: Dellabianca, Natalia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Museo Acatush un de Aves y Mamiferos Marinos Australes; ArgentinaFil: Pimper, Lida Elena. Museo Acatush un de Aves y Mamiferos Marinos Australes; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; ArgentinaFil: Pereyra Bonnet, Federico Alberto. Universidad de Buenos Aires. Facultad de Agronomía. Pabellón de Zootecnica. Laboratorio de Biotecnología Animal; ArgentinaFil: Cassini, Guillermo Hernán. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales; Argentina. Universidad Nacional de Lujan; ArgentinaFil: Prosser Goodall, Rae Natalie. Museo Acatush un de Aves y Mamiferos Marinos Australes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentin