Spatial variation in the diet of Patagonotothen tessellata (Pisces, Nototheniidae) from the fjords and channels of southern Chilean Patagonia

Abstract

The black southern cod, Patagonotothen tessellata, is the most important notothenioid fish species in terms of abundance in southern Chilean Patagonia. However, studies on its trophic ecology are scarce. Here we assessed the spatial variation in the diet of P. tessellata between two localities, one with oceanic influence (Staples Strait) and another with continental influence (Puerto Bories). We used permutation analysis combined with non-metric multi-dimensional scaling to evaluate spatial differences in diet. In addition, generalized additive models were used to identify the most significant environmental, biological and spatial predictors of variability in diet. The black southern cod presents spatial differences in diet composition among contrasting environmental localities. The diet in Staples Strait was characterized by the dominance of the polychaete Platynereis australis, whereas diet in Puerto Bories was characterized by crustaceans, mainly ostracods, gammarids and algae, mainly the filamentous green alga Rhizoclonium sp. and the red algae Polysiphonia sp. Diet composition did not show significant difference between sexes, whereas diet of small, medium and large fish differed to some degree. Smaller-sized P. tessellata were most likely to contain food. Salinity and temperature had significant influence on diet variability, suggesting that P. tessellata showed a greater diversity of prey items in environmental conditions with greater temperature and lower salinity. The results provide evidence of two dietary patterns depending on the type of environment in which they are distributed, highlighting the potential role of the environmental variables on the availability and abundance of potential prey and in structuring diet.

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

“…Another factor that might reduce the effects of trophic competition relates to differences in the diel activity patterns of fish (Hansen & Closs 2005;David et al 2007). The nocturnal feeding activity, for instance, has been observed for P. tessellata in the subtidal waters of Patagonian channels (Salas-Berrios et al 2013;Hüne & Vega 2015). In contrast, O. tschawytscha are diurnal feeders (Schabetsberger et al 2003).…”

Marine biodiversity at the end of the world: Cape Horn and Diego Ramírez islands

“…The shallow fish fauna in the region was dominated by the suborder Notothenioidei (cod icefish), represented by the families Bovichtidae, Eleginopsidae, Nototheniidae, Harpagiferidae and Channichthyidae [ 82 , 84 , 86 ]. These fishes play a key role in the ecosystem, occupying most of the available trophic niches [ 88 – 89 ], although dominated by detritivores that fed primarily on amphipods and isopods associated with the kelp [ 82 ]. They are also important prey for sea lions, cormorants ( Phalacrocorax atriceps ), and the magellanic penguin [ 90 – 92 ] that frequent the area.…”

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

“…En noviembre de 2014 ocurre el registro de atún lanzón en CL (PN), junto al primer mes en presentar una condición débil de El Niño (ONI: +0,52) en la región Niño 3.4 del Pacífico Suroriental. Sin embargo, en aguas oceánicas de Magallanes no se presentaron dichos valores, ocurriendo los dos registros de atunes en Magallanes (PN y PR) al menos 200 mn al interior de canales patagónicos, donde la salinidad superficial oscila entre 13,4 y 20, aumentando hacia la zona oceánica exterior o aguas profundas, bajo los 20 m de profundidad, donde la salinidad alcanza entre 33 y 33,5 (Silva & Calvete 2002, Hüne & Vega 2015. En PN y PR, los valores máximos de TSM durante noviembre de 2014 fueron de 8,6 °C, con su promedio en los primeros 10 m, un 0,76 °C más bajo que el promedio térmico, que generó un fuerte gradiente vertical.…”