| Summary: | Salinity is one of the most important structuring factors in the distribution and bioenergetics of estuarine fishes. The aims of this work were to study the distribution of the sub-Antarctic, eurythermic, euryhaline and coastal notothenioid Eleginops maclovinus in Lapataia estuary (Tierra del Fuego National Park), in relation to salinity conditions, and the effect of salinity on the oxygen con- sumption of this species. The spread of the mixing zone of Lapataia was studied and physicochemical properties (conductivity, pH, temperature and salinity) were mea- sured. Distribution of E. maclovinus juveniles was inves- tigated principally by electrofishing in the field. Oxygen consumption of absorptive and post-absorptive young-of- the-year individuals (8?10 cm total length) was analyzed by stop-flow respirometry measurements, performed at three salinities (1, 12 and 30 psu). The intermediate mixing zone is relatively small in this system, showing an exten- sion of *1.5 km upstream from Lapataia Bay. It was found that there was a strong relationship between the mixing zone and the distribution of juveniles of E. maclovinus. No differences were found in the metabolic baseline at different salinities. A punctual feeding provoked a typical SDA response, with a significant higher ingested food and metabolic scope at intermediate salinity (12 psu). An increased scope was reached by increasing the energy intake and not through a decrease in the standard metabolic rate. Under an available food condition, this capacity could result in an increased growth rate at inter- mediate salinity. Fil: Vanella, Fabián Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Duarte, Claudia Alejandra. Universidad Nacional de Tierra del Fuego. Instituto de Ciencias Polares, Recursos Naturales y Ambiente; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Lattuca, María Eugenia. Consejo Nacional de Investigaciones Científicas ...
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