Harpagifer, el colonizador de la Patagonia que llegó desde los hielos

La evolución de la fauna marina bentónica de la Antártica ha sido modelada por factores geológicos y climático-atmosféricos, como el aislamiento geográfico del continente y la posterior instalación de la Corriente Circumpolar Antártica (CCA). A pesar del aislamiento que actualmente afecta a esta región, se han planteado fuertes vínculos biogeográficos entre la península Antártica y el extremo sur de Sudamérica. Estudios recientes en invertebrados marinos han situado la divergencia hace unos 5 millones de años, asociada probablemente al incremento de la CCA. En este sentido y en el marco del proyecto “Filogeografía y divergencia molecular entre especies del género Harpagifer (Richardson, 1844) (Perciformes: Notothenioidei) de Antártica y Patagonia”, financiado por el INACH, se estimó la divergencia molecular de dos especies de peces del género Harpagifer: H. bispinis (Patagonia) y H. antarcticus (Antártica). Se utilizó el marcador molecular de la región control. Los resultados obtenidos indican que el tiempo estimado de la separación entre H. bispinis y H. antarcticus tuvo lugar durante el Pleistoceno (hace 1 millón de años, aprox.). Procesos de dispersión gatillados por la Gran Glaciación Patagónica, habrían permitido la colonización del extremo sur de América desde las islas del Arco de Scotia.Fil: Hüne, Mathias. Universidad de Magallanes; Chile. Universidad de Chile; ChileFil: Mansilla, Andrés. Universidad de Magallanes; Chile. Universidad de Chile; ChileFil: Fernandez, Daniel Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Barrera Oro, Esteban. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Poulin, Elie. Universidad de Chile; Chil

Spatial patterns of continental shelf faunal community structure along the Western Antarctic Peninsula

Knowledge of continental shelf faunal biodiversity of Antarctica is patchy and as such, the ecology of this unique ecosystem is not fully understood. To this end, we deployed baited cameras at 20 locations along ~ 500 km of the Western Antarctic Peninsula (WAP) at depths from 90 to 797 m. We identified 111 unique taxa, with mud bottom accounting for 90% of the dominant (≥ 50% cover) habitat sampled. Amphipoda comprised 41% of the total maximum number of individuals per camera deployment (MaxN) and occurred on 75% of deployments. Excluding this taxon, the highest MaxN occurred around King George/25 de Mayo Island and was driven primarily by the abundance of krill (Euphausiidae), which accounted for 36% of total average MaxN among deployments around this island. In comparison, krill comprised 22% of total average MaxN at Deception Island and only 10% along the peninsula. Taxa richness, diversity, and evenness all increased with depth and depth explained 18.2% of the variation in community structure among locations, which may be explained by decreasing ice scour with depth. We identified a number of Vulnerable Marine Ecosystem taxa, including habitat-forming species of cold-water corals and sponge fields. Channichthyidae was the most common fish family, occurring on 80% of all deployments. The Antarctic jonasfish (Notolepis coatsorum) was the most frequently encountered fish taxa, occurring on 70% of all deployments and comprising 25% of total MaxN among all deployments. Nototheniidae was the most numerically abundant fish family, accounting for 36% of total MaxN and was present on 70% of the deployments. The WAP is among the fastest warming regions on Earth and mitigating the impacts of warming, along with more direct impacts such as those from fishing, is critical in providing opportunities for species to adapt to environmental change and to preserve this unique ecosystem.Fil: Friedlander, Alan M.. National Geographic Society. Pristine Seas; Estados Unidos. University of Hawaii; Estados UnidosFil: Goodell, Whitney. University of Hawaii; Estados Unidos. National Geographic Society. Pristine Seas; Estados UnidosFil: Salinas-De-León, Pelayo. Charles Darwin Foundation Santa Cruz; Ecuador. National Geographic Society. Pristine Seas; Estados UnidosFil: Ballesteros, Enric. Consejo Superior de Investigaciones Científicas. Centre Destudis Avancats de Blanes; EspañaFil: Berkenpas, Eric. National Geographic Society. Pristine Seas; Estados UnidosFil: Capurro, Andrea Paula. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Cárdenas, César. Instituto Antártico Chileno; ChileFil: Hüne, Mathias. Fundación Ictiológica; Chile. Centro de Investigación Para la Conservación de Los Ecosistemas Australes; ChileFil: Lagger, Cristian Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; ArgentinaFil: Landaeta, Mauricio F.. Universidad de Valparaiso; ChileFil: Muñoz, Alex. Pristine Seas, National Geographic Society; Estados UnidosFil: Santos, Mercedes. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Turchik, Alan. National Geographic Society. Pristine Seas; Estados UnidosFil: Werner, Rodolfo. The Pew Charitable Trusts & Antarctic And Southern Ocea; Estados UnidosFil: Sala, Enric. National Geographic Society. Pristine Seas; Estados Unido

Genomics of Secondarily Temperate Adaptation in the Only Non-Antarctic Icefish

White-blooded Antarctic icefishes, a family within the adaptive radiation of Antarctic notothenioid fishes, are an example of extreme biological specialization to both the chronic cold of the Southern Ocean and life without hemoglobin. As a result, icefishes display derived physiology that limits them to the cold and highly oxygenated Antarctic waters. Against these constraints, remarkably one species, the pike icefish Champsocephalus esox, successfully colonized temperate South American waters. To study the genetic mechanisms underlying secondarily temperate adaptation in icefishes, we generated chromosome-level genome assemblies of both C. esox and its Antarctic sister species, Champsocephalus gunnari. The C. esox genome is similar in structure and organization to that of its Antarctic congener; however, we observe evidence of chromosomal rearrangements coinciding with regions of elevated genetic divergence in pike icefish populations. We also find several key biological pathways under selection, including genes related to mitochondria and vision, highlighting candidates behind temperate adaptation in C. esox. Substantial antifreeze glycoprotein (AFGP) pseudogenization has occurred in the pike icefish, likely due to relaxed selection following ancestral escape from Antarctica. The canonical AFGP locus organization is conserved in C. esox and C. gunnari, but both show a translocation of two AFGP copies to a separate locus, previously unobserved in cryonotothenioids. Altogether, the study of this secondarily temperate species provides an insight into the mechanisms underlying adaptation to ecologically disparate environments in this otherwise highly specialized group

Estructura del ensamble de peces costeros de los canales y fiordos de la zona central de la Patagonia chilena (48º-52ºS)

The central coast of Patagonia (48°-52°S) is a particular area to assess the diversity and structure of fish assemblage due to the different oceanographic gradients. In this study, we determined the identity, richness, and diversity indices, and characterized the structure of the coastal fish assemblage by non-parametric analysis of variance using permutations and multidimensional scaling including 6 localities with oceanic influence and 6 localities with continental influence, associated with Western and Eastern sectors of the channel system, respectively. A total of 380 coastal fish specimens, belonging to 17 species from 12 families, were collected. Species richness showed significant differences between the locations analyzed, with greater richness in locations associated with the sectors of East. In turn, there were no significant differences using the Shannon diversity index between groups of stations. Significant differences were found in the composition of assemblages between clusters East-West, identifying 8 species that contributed to the dissimilarity between assemblages by SIMPER test. The Patagonian blenny, Eleginops maclovinus, was the species that most contributed to the dissimilarity, followed by the notothenioid fish Patagonotothen cornucola and silverside Odontesthes regia. The changes observed in species richness and assemblage composition, suggest that the fish from the coastal ecosystem of the channels and fjords of central Patagonia, presents a longitudinal pattern of structuring; regarding the composition of the assemblage between East and West locations, which could be related to environmental variables (e.g., salinity and glacial sedimentation) present in this area.La costa de la zona central de la Patagonia (48°-52°S) representa un área particular para evaluar la diversidad y estructura del ensamble de peces, a causa de los diversos gradientes oceanográficos que exhibe. En este estudio, se determinó la identidad, riqueza, índices de diversidad y se caracterizó la estructura del ensamble de peces costeros mediante análisis de varianza no paramétrico utilizando permutaciones y escalamiento multidimensional. Se incluyó 6 localidades con influencia oceánica y 6 localidades con influencia continental, asociados a sectores Oeste y Este del sistema de canales, respectivamente. Se capturó un total de 380 peces costeros, correspondiente a 12 familias y 17 especies. La riqueza de especies presentó diferencias significativas entre las localidades analizadas, con una mayor riqueza en las localidades asociadas al sector Este. A su vez, no se observaron diferencias significativas mediante el índice de diversidad de Shannon entre los grupos de estaciones. Se observaron diferencias significativas en la composición de los ensambles entre las agrupaciones Este-Oeste, identificándose 8 especies que contribuyeron a la disimilitud entre los ensambles mediante la prueba SIMPER, siendo el róbalo, Eleginops maclovinus, la especie que más contribuyó a la disimilitud, seguido por el pez de piedra, Patagonotothen cornucola, y el pejerrey, Odontesthes regia. Los cambios observados en la riqueza de especies y composición del ensamble, sugieren que los peces en el ecosistema costero de canales y fiordos de la zona central de la Patagonia, presenta un patrón longitudinal de estructuración, en cuanto a la composición del ensamble entre localidades Este y Oeste, que podría estar relacionado a las variables ambientales (e.g., salinidad y sedimentación glacial) presentes en esta zona

PRIMER REGISTRO DE NESSORHAMPHUS INGOLFIANUS (SCHMIDT, 1912) EN AGUAS CHILENAS (ANGUILLIFORMES: DERICHTHYIDAE) FIRST RECORD OF NESSORHAMPHUS INGOLFIANUS (SCHMIDT, 1912) IN CHILEAN WATERS (ANGUILLIFORMES: DERICHTHYIDAE)

<abstract language="eng">The finding of three specimens of Nessorhamphus ingolfianus (Schmidt 1912), obtained in front of Valdivia (39º 44'S; 70º 39'W) is reported. This proves to be the first record of this species for the Southeastern Pacific and for the Chilean ichthyofauna

Presencia de atún lanzón en la costa sur de Chile: Potencial nuevo recurso para la pesca artesanal

La presente investigación analizó la abundante y masiva presencia de “atún lanzón”, Allothunnus fallai en 1.026 m.n. costeras del sur de Chile (37°03’-51°49’S), entre 2014 y 2017, incluidos el interior de los canales Magallánicos de Patagonia chilena. Se descartó que incrementos locales de la TSM provocados por El Niño causaran la presencia de la especie, cuyo arribo a la costa chilena se asociaría a la disminución de la producción primaria oceánica, provocando un acercamiento a la costa en busca de alimento. Producto de su abundancia, en 2017 y 2018 el Estado Chileno oficializó al “atún lanzón” como nuevo recurso pesquero artesanal chileno.Current investigation analysed an abundant and massive presence of “slender tuna” Allothunnus fallai through 1,026 nautical miles in the southern Chile coastline (37°03’-51°49’S), between 2014 and 2017, included its presence inner the Magellanic channels of Chilean Patagonia. We refuse that the presence of the species is linked with coastal SST increases derived from El Niño, which arrival to the Chilean coast would be associated to lowered primary oceanic production, causing an approach to Chilean coastal waters in search of food. Due its abundance in 2017 and 2018 Chilean State has formalized the “slender tuna” as a new Chilean official artisan fishing resource

Trophic relationships of a subtidal fish assemblage in the Francisco Coloane Coastal Marine Protected Area, southern Chilean Patagonia

A combination of stomach content and nitrogen (δ15N) and carbon (δ13C) stable-isotope analysis was used to assess the trophic interactions and feeding habits of three notothenioid coastal fish (Champsocephalus esox, Patagonotothen tessellata and Patagonotothen cornucola) and one exotic salmon species (Oncorhynchus tschawytscha) with diverse life habits (benthic and benthopelagic) in the Francisco Coloane Coastal Marine Protected Area, southern Chile. The stomach contents of C. esox were mainly fish; those of P. cornucola and O. tschawytscha were crustacean decapods, Munida gregaria. A cluster analysis on isotope data and stable-isotope Bayesian ellipses detected two different predator groups, one with benthopelagic habits (C. esox and O. tshawytscha) and one with benthic habits (P. cornucola and P. tessellata). These results were supported with similar isotopic trophic level of each group. We suggest that the exotic salmon O. tschawytscha is a generalist predator with a broad trophic niche that may compete with the native notothenioid C. esox, as both have equivalent trophic levels with substantial overlap. This preliminary study is the first on trophic relationships of a subtidal fish assemblage within a remote ecosystem of fjords and channels in Chile’s southern Patagonia

Egg masses of the Patagonian squid (Doryteuthis Amerigo gahi) attached to giant kelp (Macrocystis pyrifera) in the sub-Antarctic ecoregion

Egg masses of the Patagonian squid Doryteuthis (Amerigo) gahi attached to giant kelp (Macrocystis pyrifera) in the Magellanic channels of the sub-Antarctic ecoregion in southern South America is documented for the first time. Of seven egg masses observed between 2008 and 2011, one was taken to the laboratory to be analysed and photographed. Comprising long transparent capsules containing eggs, the masses were strongly attached to the stipes of M. pyrifera. This macroalgae is a potentially important economic resource due to its multiple industrial uses; this study shows that it also serves an important ecological role as a spawning substrate for D. gahi.Keywords: Doryteuthis; egg masses; giant kelp; Patagonian squid; sub-Antarctic ecoregion(Published: 5 November 2014)Citation: Polar Research 2014, 33, 21636, http://dx.doi.org/10.3402/polar.v33.2163

Divergence between Antarctic and South American marine invertebrates: what molecular biology tells us about Scotia Arc geodynamics and the intensification of the Antarctic Circumpolar Current

Continental drift processes such as major gateway openings have been historically advocated to explain the distribution of marine benthic taxa in the Southern Ocean (SO). The separation between Antarctic Peninsula and the southern tip of South America together with the onset of the Antarctic Circumpolar Current (ACC) represent the final step for the complete isolation of the Antarctic region. However, there is still controversy concerning the timing and mode of this process, and especially about the role of the Scotia Arc geodynamics in the development of a fully deep and intensified ACC circulation. Based on mitochondrial Cytochrome c Oxidase Subunit I (COI) sequences obtained from different taxa, we performed molecular comparisons between Antarctic and South American relatives to provide independent time estimations of Antarctica's isolation. We include in the analyses congeneric Antarctic and Patagonian near-shore marine benthic invertebrates including indirect developers (Nacella, Yoldia, Sterechinus, and Parbolasia) and brooders (Xymenopsis and Trophonella). Considering the levels of genetic differentiation between relatives from both regions and assuming the molecular clock hypothesis, we estimated the onset of their respective divergence. On one hand, similar levels of genetic distance in broadcast–spawners (7%–8.3%) support the hypothesis that the development of an effective barrier between Antarctica and South America occurred almost simultaneously for these groups. Divergence time estimations based on specific substitution rates indicate that the separation occurred near the Mio-Pliocene transition, long after the physical separation of both continents. Genetic distance and divergence time estimation in direct developers indicate an older separation time, close to the mid-Miocene. Even when the analyzed groups included both broadcast–spawners and brooder organisms, the divergence between Antarctic and South America lineages rather than being related to processes of continental drift, seems to be associated more to major changes in the Southern Ocean such as the evolution of the Scotia Arc and the deepening of the Drake Passage. Accordingly, these results support a genetic continuity between Antarctica and South America, probably along the Scotia Ridge, until the middle Miocene and a late ACC intensification at the Mio-Pliocene boundar