Erik Jeppesen

TY - UNPB

T1 - Food webs patterns in species-poor insular lakes resemble climate-related patterns in continental lakes

AU - Vidal, Nicolas

AU - Amsinck, Susanne Lildal

AU - Goncalves, Vitor

AU - Azevedo, José Manuel Neto

AU - Johansson, Liselotte Sander

AU - Christoffersen, Kirsten Seestern

AU - Lauridsen, Torben Linding

AU - Søndergaard, Martin

AU - Bjerring, Rikke

AU - Landkildehus, Frank

AU - Brodersen, Klaus P.

AU - Meerhoff, Mariana

AU - Jeppesen, Erik

PY - 2015

Y1 - 2015

N2 - Space-for-time substitution studies (SFTS, e.g. latitudinal gradient analyses) are often used to unravel climate effects on lake biota, and have shown a reduction in size, changes in diet and more frequent reproduction of fish in warmer climates, with cascading effects such as lower zooplankton and higher phytoplankton biomasses. SFTS results from continental lakes are, however, potentially confounded by biogeographical and evolutionary differences leading to often higher species richness in warm lakes. To somehow reduce these confounding effects, we studied species-poor lakes located in two remote island groups with contrasting climates but similar seasonality: The Faroe Islands (cold; 6.5±2.8°C) and the Azores (warm; 17.3±2.9°C). We analysed community and food web structure using a stable isotopes approach investigating fish, macro-invertebrates, and zooplankton in 20 lakes. We found a smaller mean body size of fish in the Azorean lakes even if standardised by maximum length of the fish species present, suggesting a higher predation pressure on zooplankton and consequently higher phytoplankton abundance at the same nutrient levels. A triangular shape of the food web, with wider carbon range for basal organisms and for the whole food web appeared in the colder lakes. In contrast to previous works, though, Layman metrics of the fish food web were similar between the two climatic regions despite differences in basal organisms. Our results from insular systems showed a reduced fish body size structure in the warmer region and suggest that temperature differences may drive the changes in fish size structure.

AB - Space-for-time substitution studies (SFTS, e.g. latitudinal gradient analyses) are often used to unravel climate effects on lake biota, and have shown a reduction in size, changes in diet and more frequent reproduction of fish in warmer climates, with cascading effects such as lower zooplankton and higher phytoplankton biomasses. SFTS results from continental lakes are, however, potentially confounded by biogeographical and evolutionary differences leading to often higher species richness in warm lakes. To somehow reduce these confounding effects, we studied species-poor lakes located in two remote island groups with contrasting climates but similar seasonality: The Faroe Islands (cold; 6.5±2.8°C) and the Azores (warm; 17.3±2.9°C). We analysed community and food web structure using a stable isotopes approach investigating fish, macro-invertebrates, and zooplankton in 20 lakes. We found a smaller mean body size of fish in the Azorean lakes even if standardised by maximum length of the fish species present, suggesting a higher predation pressure on zooplankton and consequently higher phytoplankton abundance at the same nutrient levels. A triangular shape of the food web, with wider carbon range for basal organisms and for the whole food web appeared in the colder lakes. In contrast to previous works, though, Layman metrics of the fish food web were similar between the two climatic regions despite differences in basal organisms. Our results from insular systems showed a reduced fish body size structure in the warmer region and suggest that temperature differences may drive the changes in fish size structure.

M3 - Working paper

BT - Food webs patterns in species-poor insular lakes resemble climate-related patterns in continental lakes

ER -