Enzymatic efficiency of the decomposing microbiota: what does really matter for aquatic macrophytes invasions?

ABSTRACT

Biological invasions have negative impacts on different ecosystem-level functions, such as nutrient cycling. In aquatic environments, exotic litter can change the activity of the decomposer microbiota. We tested whether litter quality, litter decay, and enzyme activity differed between nativeEgeria densaand exoticHydrilla verticillata. The invasive plant presented higher lignin and lower cellulose content than the native plant. Both species showed rapid fibre decay in the first five days.E. densahad higher cellulose and hemicellulose decay thanH. verticillatta. Although the species did not exhibit differences in enzyme activity over time,E. densahad a higher enzymatic efficiency thanH. verticillata. This differential enzymatic performance can cause changes in the mineralisation processes of the invaded environments. The lower decomposition rates for invasive litter, associated with differences in litter quality, could increase the amount of particulate organic material in invaded environments.

Keywords:
environmental impact; freshwater; litter decay; microbiological processes; refractory litter