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| Provedor de dados: |
OceanDocs
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| País: |
Belgium
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| Título: |
Estrategias de vida de los copépodos Drepanopus forcipatus y Calanus australis en relación con los recursos tróficos en la plataforma patagónica austral (Argentina, 47°- 55°S)
Life strategies of two copepods Drepanopus forcipatus y Calanus australis in relation to trophic resources in the Southern Patagonian shelf (Argentina, 47º- 55ºS)
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| Autores: |
Antacli, J.C.
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| Data: |
2012-03-21
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| Ano: |
2011
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| Palavras-chave: |
Zooplankton
Trophic levels
Population structure
Hydrography
Community composition
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| Resumo: |
This Thesis contributes to elucidate the life cycle strategies of two copepod species, the medium-size clausocalanid Drepanopus forcipatus Giesbrecht, 1888 and the large calanid Calanus australis Brodsky, 1959, in relation to the environmental conditions in the southern Patagonian shelf (47°-55°S). This research was mainly carried out with samples collected in late summer/early autumn (March/April, 2004) onboard RV "Dr. E. L. Holmberg" (INIDEP, Mar del Plata). An additional sampling performed during early spring (October, 2005) with RV "Puerto Deseado" (CONICET) was also utilized. The present study was based on the following research questions: 1) Which is the available food for copepod populations by late summer? 2) Which is the relative contribution of D. forcipatus and C. australis to the summer mesozooplankton community conformation in the southern Patagonian shelf when it is determined from samples collected by a fine mesh size net? 3) Which feeding and reproductive activity levels do D. forcipatus and C. australis have by late summer? 4) Which are the strongest trophic links of D. forcipatus and C. australis to lower trophic levels by late summer in the region? 5) Which are the adaptive strategies of D. forcipatus and C. australis to cope with seasonal food variability? In the southern Patagonian shelf, the mesozooplankton overall structure and that of its populations have been historically misinterpreted because of sampling with coarse nets. Environmental conditions during late summer in the study area corresponded with a post phytoplankton bloom stage and, consequently, food availability in the size range efficiently ingested by copepods ( 10 ìm) was low. Both species revealed a seasonal pattern in feeding and reproduction, low in summer and high in spring, in coincidence with food availability in situ. D. forcipatus and C. australis may have diminished metabolism as an adaptation to poor food conditions, although apparently had not fully entered yet in a resting stage (dormancy). D. forcipatus may perform an opportunistic and rather flexible strategy when facing low concentrations of optimal food. This copepod would be capable of exploiting the actually available resources, and to sustain reproduction under low food availability. C. australis would be adapted to seasonally variable trophic conditions, would select food by particle size and would be able to reproduce with low or no food, at the expense of a combination of ingestion and assimilation of the lipid reserves stored during development
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| Tipo: |
Theses and Dissertations
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| Idioma: |
Espanhol
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| Identificador: |
http://hdl.handle.net/1834/4205
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| Formato: |
210 p.
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