No abstract

No abstract

Nevertheless, between 1985Nevertheless, between and 1997Nevertheless, between and between 1997Nevertheless, between and 2007, the estimated number of sea lions showed a stable or slightly negative trend of 0.4 ± 0.1 % yr -1 and 0.5 ± 0.1 % yr -1 , respectively. We suggest that the overexploitation and decline of the principal fisheries in Central Chile could adversely impact the abundance and distribution of the South American sea lion in the study area.Key words: census, Chilean coast, Otaria flavescens, overexploitation, sea lions. RESUMENSe estimó la distribución y la abundancia poblacional del lobo marino común Otaria flavescens en la costa de Chile central durante los meses de enero y febrero de 2007. Adicionalmente, se analizaron los cambios en la abundancia de esta especie durante el período 1970-2007. Los censos poblacionales se basaron en fotografías tomadas desde embarcaciones menores o desde avionetas. Se contabilizaron un total de 16301 lobos marinos (IC = 16209-16375) en 33 colonias (6 reproductivas y 27 no reproductivas). Después de corregir por la proporción de animales en el agua y por crías no registradas al momento del censo, se estimó una abundancia promedio de 18179 (95 % IC = 17777-18851) lobos marinos en el área de estudio. El análisis de tendencia poblacional presentó que desde 1970 a 1985 la abundancia del lobo marino común mostró un crecimiento positivo de aproximadamente 2.1 % año -1 . Sin embargo, entre 1985 y 1997, y entre 1997 y 2007, el número de lobos marinos muestra una tendencia estable o ligeramente negativa de 0.4 ± 0.1 % año -1 y 0.5 ± 0.1 % año -1 , respectivamente. Se sugiere que la sobreexplotación y la declinación de las principales pesquerías en la zona central de Chile podrían haber impactado negativamente la distribución y abundancia del lobo marino común en el área de estudio.

El Niño induced changes of the coastal fish fauna off northern Chile and implications for ichthyogeographywere typical for sandy beaches and 14.6% for rocky shores. The shore fish community did not show major changes during and after EN events, as only a few invading species were recorded; just Umbrina xantii was found during all events considered. In order to understand the response of the fish community to ENSO events a biogeographical analyses of 721 fish species reported for neritic habitats (coastal epipelagic and benthic) distributed between 0°-57°S (Gulf of Guayaquil to Cape Horn) was made. Their distribution ranges for normal oceanic conditions were taken from the very numereous existing literature. It is concluded that the north/south migration of Panamic and Peruvian warm water fishes during EN/LN events along the north Chilean coast between 18º-23ºS, indicates that it represents a wide transition zone between the Peruvian and the Chilean ichthyogeographic provinces. Key words: ENSO, neritic fishes, northern Chile, ichthyogeographyResumen.-La franja costera de la zona norte de Chile (18º-23ºS) es habitada por numerosas especies de peces neríticos de las cuales 249 son comúnmente observadas durante condiciones normales y condiciones frías La Niña (LN). Durante El Niño (EN) la ictiofauna del norte de Chile experimenta cambios significativos a causa de la presencia de alrededor de 100 especies de peces invasores que durante periodos normales y/o fríos habitan en latitudes menores, siendo también nombrados "invasores septentrionales" y "peces trópico-ecuatoriales". Este conjunto incluye 15 familias y 86 géneros de peces. Los análisis mostraron que las especies afectadas por los EN no fueron las mismas durante los últimos tres eventos, revelando que solo las especies epipelágicas Anchoa naso, Albula vulpes, Atherinella nocturna y Scomberesox saurus stolatus fueron constantes. Frente al norte de Chile, durante los EN

SUMMARY: From bibliographical information on bathymetric and latitudinal distribution of 110 marine fish species of western Patagonia (42º-57ºS), the ichthyogeographic zonation of the area is discussed. The bathymetric distribution of the fish species shows a species association distributed at depths less than 100 m, a second association between 50 and 500 m, and a third association below 500 m depth. This third one is interpreted as a transitional situation of the second one, because of the scarcity of endemic species. These associations present similar latitudinal zonation patterns, including separation into a northern sector, characterized by species of lower latitudes, a southern sector with characteristic and endemic elements of that zone, and an intermediate transition sector considered as an independent association by its large extension and species composition. The Straits of Magellan represent an important faunistic exchange zone between the bottom fish communities of the Southwestern Atlantic and the Southeastern Pacific.

BackgroundA number of studies have described the extension of ice cover in western Patagonia during the Last Glacial Maximum, providing evidence of a complete cover of terrestrial habitat from 41°S to 56°S and two main refugia, one in south-eastern Tierra del Fuego and the other north of the Chiloé Island. However, recent evidence of high genetic diversity in Patagonian river species suggests the existence of aquatic refugia in this region. Here, we further test this hypothesis based on phylogeographic inferences from a semi-aquatic species that is a top predator of river and marine fauna, the huillín or Southern river otter (Lontra provocax).ResultsWe examined mtDNA sequences of the control region, ND5 and Cytochrome-b (2151 bp in total) in 75 samples of L. provocax from 21 locations in river and marine habitats. Phylogenetic analysis illustrates two main divergent clades for L. provocax in continental freshwater habitat. A highly diverse clade was represented by haplotypes from the marine habitat of the Southern Fjords and Channels (SFC) region (43°38' to 53°08'S), whereas only one of these haplotypes was paraphyletic and associated with northern river haplotypes.ConclusionsOur data support the hypothesis of the persistence of L. provocax in western Patagonia, south of the ice sheet limit, during last glacial maximum (41°S latitude). This limit also corresponds to a strong environmental change, which might have spurred L. provocax differentiation between the two environments.

No abstract

No abstract