Invasion of the Chinese mitten crabs: are they a threat to our freshwater flora?

The Chinese mitten crab is an invasive exotic species in our freshwater ecosystems and the population seems on the rise in recent years, especially in the upstream reaches of rivers. In these upstream reaches, water plants flourish and fulfill a crucial ecological role in the ecosystem. The effect of the mitten crabs on this aquatic vegetation is poorly understood. A handful of laboratory test show that macrophytes are part of the crab diet, but not exclusively. Also some case studies in the field blame the crabs to have completely clear-cut the entire aquatic vegetation, though there was no conclusive proof for that. Our hypothesis is that mitten crabs are indeed capable of heaving a devastating effect on the aquatic vegetation, but only if this vegetation is already impaired or experiences considerable levels of (abiotic) stress. In this project we will experimentally investigate whether crabs can have a negative effect on aquatic vegetation and whether this effect is bigger when plants are stressed. The studied stresses are EDTA-pollution and light stress, both factors are linked to the earlier mentioned case studies. Combining density data from literature and knowledge on herbivory pressure by certain crab densities will allow estimating the threat these crabs potentially are for the native flora in freshwater rivers.

Keywords:EXOTIC SPECIES, MACROPHYTES, AQUATIC ECOLOGY, MACRO-INVERTEBRATES

Disciplines:Geology, Ecology, Aquatic sciences, challenges and pollution, Environmental science and management, Other environmental sciences