Browsing by Author "Ehrlich, M.D."

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Esquema biogeográfico del Mar Argentino
    (Mar del Plata : Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2008) Balech, E.; Ehrlich, M.D.
    The fauna of the Argentine (SW Atlantic Ocean) shelf allows to distinguish two biogeographic provinces: the Argentine and the Magellanic that are part of the Subtropical and Subantarctic Regions. The former extends from 30° S-32° S to 41° S-44° S and from the coast to the 82-95 m isobath, between 35° S-39° S, to 70 m depth in the north Patagonia. The latter extends from the Valdés Peninsula to the southern extreme and from 43° S northward, east area of the Argentine Province. The different physiographic characteristics allow to distinguish movable sandy bottoms in the Argentine Province and in the Magellanic gravel bottoms where large algae grow. The climatic differences explain the prevalence of northern winds in the first, where warm and temperate-cold coastal waters alternate and western strong winds in the second with net predominance of subantarctic waters from the Malvinas Current. The factors mentioned explain the differences in the faunal composition of both Provinces; the Argentina is characterized by a marked heterogeneity of its components and the Magellanic by its homogeneity and own taxa. The detailed analysis of the faunal composition of both Provinces performed using benthonic organisms (echinoderms, crustaceans and molluscs) and nektonic (fishes) resulted in subdivisions that correspond to the Uruguayan District, down to 38° S-39° S and the Rionegrin, south of said latitude in the Argentine Province and the Chubutian and Southpatagonic, north and south of 47° S in the Magellanic. The hydrographic regime allowed to establish the Santacrucean and Fuegian Subdistricts within the Southpatagonic District, which supports the warm drift theory in the Uruguayan and Rionegrin Districts of the Argentine Province and in the Chubutian of the Magellanic. The feature that characterizes the Southpatagonic District is the absence of a warm water tongue.
  • No Thumbnail Available
    Item
    Ichthyoplankton composition, distribution and abundance on the southern patagonian shelf and adjacent waters.
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 1999) Ehrlich, M.D.; Sánchez, R.P.; de Ciechomski, J.D.; Machinandiarena, L.; Pájaro, M.
    This paper reviews the information on pelagic and demersal fish eggs and larvae, describing the distribution and seasonality of different species and their arrangement in icthyoplankton assemblages in the Southern patagonian waters. It also reports on 11 surveys conducted by INIDEP during 1992-1995. A total of 488 ichthyoplankton samples were analyzed. Fish eggs have been recognized in 47. of all ichthyoplankton samples. They belong to three species: Coelorhynchus fasciatus, Macrourus whitsoni and Micromesistius australis. Fish larvae of 23 species and 17 families have been identified in 96. of all samples analyzed. Spawning of most species begins in autumn, and progresses through winter, when the southern blue whiting and grenadier fish contribute to more than half of all eggs present in our samples. Nototheniid and myctophiid larvae were caught during all year long. Four larval groups were detected using cluster analysis: the first group, formed exclusively by nototheniids, which occupied a vast area on the continental shelf between 100 and 200 m depth, the second formed by Agonopsis chiloensis, Eleginops maclovinus, Macruronus magellanicus and Sprattus fuegensis in coastal waters, the third formed by myctophiids, Gymnoscopelus spp. and Micromesistius australis, inhabit the outer continental shelf and slope, and the fourth included Protomyctophum spp., Krefftichthys anderssoni and Bathylagus antarcticus, species typically found in Subantarctic waters of the Malvinas Current. Comparing the distribution of eggs and larvae of blue whiting from collections obtained during the 70's and 80's, with those of recent surveys, it is evident, that a significant contraction of the spawning grounds of the species has take place, particularly to the west of the archipelago.