| Title | Climate warming restructures an aquatic food web over 28 years |
| Abstract | limate warming can restructure lake food webs if trophic levels differ in their thermal responses, but evidence for these changes and their underlying mechanisms remain scarce in nature. Here we document how warming lake temperatures by up to 2°C, rather than changes in trophic state or fishing effort, have restructured the pelagic food web of a large European lake (Lake Maggiore, Italy). Our approach exploited abundance and biomass data collected weekly to yearly across five trophic levels from 1981 to 2008. Temperature generally had stronger effects on taxa than changes in fish predation or trophic state mediated through primary productivity. Consequently, we found that, as the lake warmed, the food web shifted in numerical abundance towards predators occupying middle trophic positions. Of these taxa, the spiny water flea (Bythotrephes longimanus) most prospered. Bythotrephes strongly limited abundances of the keystone grazer Daphnia, strengthening top-down structuring of the food web. Warmer temperatures partly re-structured the food web by advancing peak Bythotrephes densities by approximately 60 days and extending periods of positive population growth by 3-times. Nonetheless, our results suggested that advances in the timing and size of peak Bythotrephes densities could not outpace changes in the timing and size of peak densities in their Daphnia prey. Our results provide rare evidence from nature as to how long-term warming can favour higher trophic levels, with the potential to strengthen top-down control of food webs. |
| Source | Global change biology (Print) |
| Keywords | causal networksclimate changefood websoligotrophicationphenologypopulation dynamics |
| Journal | Global change biology (Print) |
| Editor | Blackwell Science., Oxford, Regno Unito |
| Year | 2020 |
| Type | Articolo in rivista |
| DOI | 10.1111/gcb.15347 |
| Authors | Andrew J. Tanentzap, Giuseppe Morabito, Pietro Volta, Michela Rogora, Norman D. Yan, Marina Manca |
| Text | 432095 2020 10.1111/gcb.15347 causal networks climate change food webs oligotrophication phenology population dynamics Climate warming restructures an aquatic food web over 28 years Andrew J. Tanentzap, Giuseppe Morabito, Pietro Volta, Michela Rogora, Norman D. Yan, Marina Manca Ecosystems and Global Change Group, Department of Plant Sciences, University of Cambridge, Cambridge, UK. Water Research Institute CNR IRSA , National Research Council, Verbania Pallanza, Italy. Department of Biology, York University, Toronto, ON, Canada limate warming can restructure lake food webs if trophic levels differ in their thermal responses, but evidence for these changes and their underlying mechanisms remain scarce in nature. Here we document how warming lake temperatures by up to 2°C, rather than changes in trophic state or fishing effort, have restructured the pelagic food web of a large European lake Lake Maggiore, Italy . Our approach exploited abundance and biomass data collected weekly to yearly across five trophic levels from 1981 to 2008. Temperature generally had stronger effects on taxa than changes in fish predation or trophic state mediated through primary productivity. Consequently, we found that, as the lake warmed, the food web shifted in numerical abundance towards predators occupying middle trophic positions. Of these taxa, the spiny water flea Bythotrephes longimanus most prospered. Bythotrephes strongly limited abundances of the keystone grazer Daphnia, strengthening top down structuring of the food web. Warmer temperatures partly re structured the food web by advancing peak Bythotrephes densities by approximately 60 days and extending periods of positive population growth by 3 times. Nonetheless, our results suggested that advances in the timing and size of peak Bythotrephes densities could not outpace changes in the timing and size of peak densities in their Daphnia prey. Our results provide rare evidence from nature as to how long term warming can favour higher trophic levels, with the potential to strengthen top down control of food webs. Published version https //onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15347 af=R Articolo in rivista Blackwell Science. 1354 1013 Global change biology Print Global change biology Print Glob. chang. biol. Print marinamarcella.manca MANCA MARINA MARCELLA michela.rogora ROGORA MICHELA pietro.volta VOLTA PIETRO |
