Scheda di dettaglio – i prodotti della ricerca

DatoValore
TitleSeasonal changes in the delta C-13 and delta N-15 signatures of the Lago Maggiore pelagic food web
AbstractSeasonal variation in the relative contributions of littoral and pelagic food sources to the diets of open-water zooplankton and subsequent changes in their trophic positions were investigated with carbon and nitrogen Stable Isotope Analysis (SIA). We selected three open water stations as truly pelagic. but also influenced by littoral and riverine carbon sources. During each of the four seasons, integrated pelagic zooplankton samples were collected over 0-50 m depth intervals at each site along with seston in the size range 1.2-76 mu m. In addition, vertical temperature profiles were measured. Littoral benthos from three sites along the main longitudinal axis of the lake was sampled to serve as a reference for tracing Lago Maggiores littoral carbon isotopic signature. Among stations differences in delta C-13 and delta N-15 signatures of the different components of the pelagic food web, from seston to predatory zooplankton, were statistically non significant, thus confirming that allochthonous input may become important only after exceptional rainfall events. Changes in the delta C-13 pelagic baseline mirrored Mean water temperature (0-50 m) seasonal changes. Similarly to Lake Geneva, they were likely driven by changes in carbon sources for phytoplankton growth during stratification and vertical water mixing. Differently from what observed fir the other taxa, the role of littoral food sources was far from negligible (>50%) for diaptomids during winter and spring. We do not know however, whether such a result could be at least partially attributed to the heavy infestation by algal epibionts. or was consequent to the fact that these zooplankters may carry littoral carbon to the pelagial via horizontal migration. In winter, Bythotrephes longimanus was able to prey on Cyclops, thus occupying a trophic position comparable to that of planktivorous fish. Such a result confirms an ability of this visual, invertebrate predator to compete with young zooplanktivorous fish for food resources, similarly to what observed in lakes it recently invaded.
SourceJournal of limnology (Testo stamp.) 70 (2), pp. 263–271
KeywordsCarbonnitrogenstable isotopeszooplankton
JournalJournal of limnology (Testo stamp.)
EditorIstituto per lo Studio degli Ecosistemi., Verbania Pallanza, Italia
Year2011
TypeArticolo in rivista
DOI10.3274/JL11-70-2-14
AuthorsVisconti, A (Visconti, Anna)[ 1 ] ; Manca, M (Manca, Marina)[ 1 ]
Text203820 2011 10.3274/JL11 70 2 14 ISI Web of Science WOS 000294320400012 Carbon nitrogen stable isotopes zooplankton Seasonal changes in the delta C 13 and delta N 15 signatures of the Lago Maggiore pelagic food web Visconti, A Visconti, Anna 1 ; Manca, M Manca, Marina 1 1 CNR Inst Ecosyst Study, I 28922 Verbania, Italy Seasonal variation in the relative contributions of littoral and pelagic food sources to the diets of open water zooplankton and subsequent changes in their trophic positions were investigated with carbon and nitrogen Stable Isotope Analysis SIA . We selected three open water stations as truly pelagic. but also influenced by littoral and riverine carbon sources. During each of the four seasons, integrated pelagic zooplankton samples were collected over 0 50 m depth intervals at each site along with seston in the size range 1.2 76 mu m. In addition, vertical temperature profiles were measured. Littoral benthos from three sites along the main longitudinal axis of the lake was sampled to serve as a reference for tracing Lago Maggiores littoral carbon isotopic signature. Among stations differences in delta C 13 and delta N 15 signatures of the different components of the pelagic food web, from seston to predatory zooplankton, were statistically non significant, thus confirming that allochthonous input may become important only after exceptional rainfall events. Changes in the delta C 13 pelagic baseline mirrored Mean water temperature 0 50 m seasonal changes. Similarly to Lake Geneva, they were likely driven by changes in carbon sources for phytoplankton growth during stratification and vertical water mixing. Differently from what observed fir the other taxa, the role of littoral food sources was far from negligible >50% for diaptomids during winter and spring. We do not know however, whether such a result could be at least partially attributed to the heavy infestation by algal epibionts. or was consequent to the fact that these zooplankters may carry littoral carbon to the pelagial via horizontal migration. In winter, Bythotrephes longimanus was able to prey on Cyclops, thus occupying a trophic position comparable to that of planktivorous fish. Such a result confirms an ability of this visual, invertebrate predator to compete with young zooplanktivorous fish for food resources, similarly to what observed in lakes it recently invaded. 70 ID_PUMA cnr.ise/2011 A0 034 Seasonal changes in the delta C 13 and delta N 15 signatures Seasonal_changes_in_the_delta_C_13_and_delta_N_15_signatures.pdf Articolo in rivista Istituto per lo Studio degli Ecosistemi. 1129 5767 Journal of limnology Testo stamp. Journal of limnology Testo stamp. J. limnol. Testo stamp. Journal of limnology. Testo stamp. VISCONTI ANNA marinamarcella.manca MANCA MARINA MARCELLA DG.RSTL.094.012 Evoluzione della biodiversita e valutazione della banca degli stadi duraturi di organismi acquatici di laghi remoti