Size and configuration of freshwater ecosystems

The dynamics of spatially compressed food webs

Habitat loss is the main force driving global species loss, and destabilisation of food webs caused by reduced habitat size is a likely mechanism for these biodiversity declines.

Compression of habitats can restrict the movement of organisms, concentrating species interactions such as competition and predation. It could also limit renewal of prey resources, meaning that areas can only support smaller population sizes and making them more vulnerable to stochastic effects such as major disturbances. Additionally, reductions in habitat size likely limit refuges for prey, increasing the effects of predation. These processes are thought to reduce food web stability, but there has been a general lack of studies revealing the dynamic consequences of reductions in habitat size, despite their likely importance. Streams offer excellent opportunities for natural size-based experiments.

Detailed knowledge of New Zealand stream food webs also suggests larger streams support more predator biomass, implying they are more stable. Using replicated experiments across streams of different sizes and streams contracted due to lowered flows, Pete McHugh and Angus McIntosh will investigate how reductions in the spatial extent of habitat influence food web stability. This will provide important insights into how habitat loss contributes to biodiversity loss, especially in stream ecosystems.

People involved in this project

University of Canterbury
Angus McIntosh
Peter McHugh

Monash University
Ross Thompson