Climate change is predicted to increase the intensity of extreme climatic events such as severe droughts. Little is known on how freshwater ecosystems respond to severe droughts in the neotropics. Terrestrial organic matter, primarily derived from plant litter, represents an important food resource in these nutrient limited freshwater ecosystems.
The PhD project currently being undertaken by Camille Bonhomme from Universidade Federal do Rio de Janeiro (UFRJ) wants to investigate the effects of quantity of terrestrial matter subsidies on the response of the recipient aquatic communities to drought stress.
Camille will use tank bromeliads along with their associated aquatic invertebrates as model ecosystems. Tank bromeliads are neotropical plants. Their interlocking leaves form rosettes that collect rainwater and dead leaves from the overhanging trees, creating an aquatic habitat for various species of invertebrates.
In the field experiment, bromeliads will receive either few or high quantities of leaf litter inputs. After a natural colonisation and equilibration period, the diversity and composition of the aquatic invertebrate community that colonised the bromeliads will be assessed and compared to the quantity of subsidised resources. The bromeliad micro-ecosystems will then be submitted to a drying and rewetting event, to assess their resistance and resilience.
Camille hopes to show firstly that the variations in leaf litter provision will determine the composition and quality of the colonisation (including number of species, food chain length and overall community composition).
Secondly, that the leaf litter quantity will affect the stability of the community submitted to drought, expecting the higher provision of leaf litter to give greater support, by offering a “buffering” effect to the community. It is hoped to show that leaf litter will provide short term refuges for invertebrates and be more attractive for recolonisation after the drought.
We look forward to seeing the result of Camille’s research.