Browsing by Author "Castillo, Jorge Gonzalo"
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Item Mass mortality in the benthic infauna of port foster resulting from the eruptions in Deception Island (South Shetland Is.)(1968) Gallardo, Victor Ariel; Castillo, Jorge GonzaloOn December 21 and 31, 1967 a limited survey of the bottom was carried out by the authors to observe the effects of the volcanic events of Dec. 4 on the benthic nfauna of Port Foster. Fifteen 0.1 m2 and one 0.2 m2 Petersen grab samples, and five dredge hauls gave evidence that most of the bottom had been covered by a layer of ash of a minimum thickness of 30 cm. Bottom samplers caught little if no infauna in the greater part of Port Foster and dredgings from the same area showed no residues of the previously existing infauna. Comparison with yields from samples taken on a previous year at Port Foster and outside the bay gave an idea of the extent of the mortality. Near the mouth of Port Foster, where the bottom does not show considerable ash covering, infaunal animals were more numerous. A dredge haul here caught many specimens of living Ophionotus victoriae, together with some dead ones. Also all Echinoidea (Sterechinus neumayeri) were dead and in advanced state of decomposition. Mortality in this case was presumably due to other chemical or physico-chemical factors. Other causes of mortality in the bottom fauna of Port Foster were: the uplift of the bottom and the formation of a new islet at Telefon Bay, the high concentration of toxic cornpounds and the high temperature reached by the water nearby. Further alterations of the ecosystem at Port Foster were evidenced by the absence of fish and other sea life at the time of the observations. Turbidity of the water and the presence of toxic compounds might have also altered the productivity of the surface layers. Port Foster is now an excelent spot to study the reestablishment of an ecosystem in relation to the evolution of all parameters to normality.