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Zooplankton body size under warmer and more fluctuating climate: insights from a long-term mesocosm experiment

Chaguaceda Borjabad, Fernando (2015) BION01 20142
Degree Projects in Biology
Abstract
Body size is one of the most important traits of zooplankton. It affects their metabolism, life history and ecology and can eventually influence community and ecosystem processes. Higher and more fluctuating temperatures due to climate change are expected to have an influence on zooplankton size. Based on general empirical evidence, warmer temperatures may lead to smaller zooplankton, while temperature fluctuation may either favour small resilient species or big resistant counterparts. In order to find evidences of how zooplankton body size reacts to a 100-year climate change scenario, we used a long-term mesocosm study mimicking natural lake conditions (n=24), in which 8 replicates were randomly subjected to one of three treatments i.e.... (More)
Body size is one of the most important traits of zooplankton. It affects their metabolism, life history and ecology and can eventually influence community and ecosystem processes. Higher and more fluctuating temperatures due to climate change are expected to have an influence on zooplankton size. Based on general empirical evidence, warmer temperatures may lead to smaller zooplankton, while temperature fluctuation may either favour small resilient species or big resistant counterparts. In order to find evidences of how zooplankton body size reacts to a 100-year climate change scenario, we used a long-term mesocosm study mimicking natural lake conditions (n=24), in which 8 replicates were randomly subjected to one of three treatments i.e. C- ambient temperature, T- 4°C > ambient temperature, F- 4°C > ambient temperature + higher fluctuation. Our results showed ambiguous size responses to warming: in zooplankton populations, big size differences occurred in the winter time, with smaller Bosmina longirostris and cyclopoid copepods but bigger calanoid copepods. At the community level, calanoid copepods tended to be more abundant in warmer conditions. However, that did not lead to significant differences in community average body size, suggesting that the size response might be buffered at higher levels of organization. Temperature fluctuation did not favour either big resistant species or small resilient species. Overall, the effect of warming plus temperature fluctuation on zooplankton tended to be lower than the effect of warming alone in all variables measured and for all taxa, suggesting that higher fluctuations may hamper the effects of climate warming. However, a heatwave prevented the summer abundance peak of B. longirostris in F, highlighting the importance of timing of extreme events on the final biological response. This study provides evidence of size shifts under warming treatments. However further studies are needed in order to obtain a more complete picture of the climate change responses of aquatic ecosystems. (Less)
Popular Abstract
Zooplankton body size under warmer and more fluctuating climate


Body size is one of the most ecologically-relevant features of an organism. It can give traces of its biomass, age, sex, growth rate, etc., and more importantly, how the organism interacts with the rest of the ecosystem, (e.g. predation susceptibility, feeding rates).

In nature, there is a general trend where organisms tend to be smaller in warmer and bigger in colder environments when comparing across a wide latitude range. Overall, this is also what happens with the small invertebrates that comprise zooplankton, where one can find the biggest near the poles and the smallest in tropical regions. Higher temperature fluctuation may also affect the body size of... (More)
Zooplankton body size under warmer and more fluctuating climate


Body size is one of the most ecologically-relevant features of an organism. It can give traces of its biomass, age, sex, growth rate, etc., and more importantly, how the organism interacts with the rest of the ecosystem, (e.g. predation susceptibility, feeding rates).

In nature, there is a general trend where organisms tend to be smaller in warmer and bigger in colder environments when comparing across a wide latitude range. Overall, this is also what happens with the small invertebrates that comprise zooplankton, where one can find the biggest near the poles and the smallest in tropical regions. Higher temperature fluctuation may also affect the body size of zooplankton by either favouring smaller fast-growing species, which are more resilient to changes in their environment, or big species, which are more resistant .

The latest report of the Intergovernmental Panel for Climate Change (IPCC, 2013) predict an increase of 4°C in mean surface temperatures and also a substantial increase of the temperature fluctuation at the end of this century. Then, one question remains rather unexplored: (1) does zooplankton become smaller as the water gets warmer and more fluctuating due to the climate change?

To test that question, I used 24 big aquarias called mesocosms, that mimicked the conditions of real lakes. Some of them were treated with the future climate change conditions for warming and temperature fluctuation, working as ”time machines” for lake ecosystems.

My results showed different responses for different species and at population and community level: in zooplankton populations, big differences in size were found in the winter, when Bosmina longirostris became smaller and cyclopoid copepods tend to become smaller under climate warming. However, against our predictions, calanoid copepods became bigger in the future warmer conditions. Changes at population level did not lead to significant differences in average community body size, what may tell us that ecosystems might buffer the response at higher levels of organization.

Overall, I did not see temperature fluctuation favouring either big more resistant species or small resilient species. One interesting pattern is that the effect of both warming + temperature fluctuation on zooplankton tended to be lower than the effect of warming alone, suggesting that higher fluctuations may hamper the effects of climate warming. However, a heatwave in the middle of the summer reduced a lot the abundance peak of B. longirostris, highlighting the importance of timing of extreme events on the final biological response. This study provides evidences of size shifts under warming treatments, which would likely affect future lake ecosystems. However, further studies are needed to obtain a more complete picture of what awaits our lakes in the future.

Supervisor: Lars-Anders Hansson
Master´s Degree Project in Biology (Aquatic Ecology), 45 cr, 2015
Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
author
Chaguaceda Borjabad, Fernando
supervisor
organization
course
BION01 20142
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
7374768
date added to LUP
2015-06-22 14:26:36
date last changed
2015-06-22 14:26:36
@misc{7374768,
  abstract     = {Body size is one of the most important traits of zooplankton. It affects their metabolism, life history and ecology and can eventually influence community and ecosystem processes. Higher and more fluctuating temperatures due to climate change are expected to have an influence on zooplankton size. Based on general empirical evidence, warmer temperatures may lead to smaller zooplankton, while temperature fluctuation may either favour small resilient species or big resistant counterparts. In order to find evidences of how zooplankton body size reacts to a 100-year climate change scenario, we used a long-term mesocosm study mimicking natural lake conditions (n=24), in which 8 replicates were randomly subjected to one of three treatments i.e. C- ambient temperature, T- 4°C > ambient temperature, F- 4°C > ambient temperature + higher fluctuation. Our results showed ambiguous size responses to warming: in zooplankton populations, big size differences occurred in the winter time, with smaller Bosmina longirostris and cyclopoid copepods but bigger calanoid copepods. At the community level, calanoid copepods tended to be more abundant in warmer conditions. However, that did not lead to significant differences in community average body size, suggesting that the size response might be buffered at higher levels of organization. Temperature fluctuation did not favour either big resistant species or small resilient species. Overall, the effect of warming plus temperature fluctuation on zooplankton tended to be lower than the effect of warming alone in all variables measured and for all taxa, suggesting that higher fluctuations may hamper the effects of climate warming. However, a heatwave prevented the summer abundance peak of B. longirostris in F, highlighting the importance of timing of extreme events on the final biological response. This study provides evidence of size shifts under warming treatments. However further studies are needed in order to obtain a more complete picture of the climate change responses of aquatic ecosystems.},
  author       = {Chaguaceda Borjabad, Fernando},
  language     = {eng},
  note         = {Student Paper},
  title        = {Zooplankton body size under warmer and more fluctuating climate: insights from a long-term mesocosm experiment},
  year         = {2015},
}