How do current insect dispersal dynamics compare to natural rates-of-change?

Theme: Biodiversity, Ecology & Conservation

Primary Supervisor:

Stefan Engels

Department of Geography, BBK

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Secondary Supervisor:

Ian Matthews

Department of Geography, RHUL

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Project Description:

Insect numbers and population diversity in NW Europe have decreased by as much as 75% over the past few decades – a so-called ‘Insect Armageddon’. Insects are keystone organisms in natural food webs and fulfil a vital role as crop plant pollinators. The alarming decline in insect numbers therefore poses a real threat to natural ecosystem functioning as well as to global food security. However, there are not just “losers” in this situation, and due to global warming multiple insect species in NW Europe are expanding their distribution ranges northward. It is currently unclear if the rate at which species can change their distribution rate in the current-day environment, where many anthropogenic actions impact on insect populations simultaneously, are as fast as they were naturally.
Subfossil chironomid (non-biting midges) remains as stored in lake sediment records provide a unique way to reconstruct long-term changes in insect diversity. Chironomids are often the most abundant invertebrates in a lake and they are highly sensitive to changes in their environment. The preservation of parts of their exoskeleton in lake sediment records allows us to determine changes in the chironomid fauna through time.
This project will determine to what extent current changes in chironomid distribution patterns are different from natural rates-of-change. Datasets from existing Holocene records will be analysed and, where necessary, complemented by new records that will be retrieved from selected shallow lakes in areas that have seen dramatic changes in their insect community. The records will be analysed with a sub-decadal resolution in order to reconstruct past trends in the chironomid fauna and dated using a range of chronological techniques. By understanding how insect diversity has varied across the last few decades as well as in deep time, we will be better able to predict how the current decline in insects will develop in the near future.

Policy Impact of Research:

Climate change and anthropogenic land use affect all aspects of ecosystems, but freshwater ecosystems and their invertebrate faunas are particularly affected. Better understanding of insect diversity responses to external drivers such as climate change has important implications for ecosystem functioning, food supply and wider economic impacts.

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