Rising CO₂ concentrations and the resulting shifts in hydrology can have direct and indirect impacts on organisms and communities. The system studied was aquatic container habitats, where mosquito larvae often compete for food resources. I hypothesized that elevated atmospheric CO₂ concentrations (Chapter 2) and extreme precipitation regimes (Chapter 3) would alter leaf chemistry and competition between two locally competing mosquito species, Aedes albopictus and Aedes triseriatus in laboratory microcosm experiments. In Chapter 2, tannin concentration was higher in leaves grown under elevated CO₂ conditions than ambient, but competition was not affected. A two-fold increase was observed in leaf biomass in the elevated CO₂ chamber, and increasing leaf litter to a container system could increase toxicity to mosquito larvae. In Chapter 3, simulated drought conditions decreased leaf decay rate and increased tannin concentrations compared to continuously wet and wet-dry leaves, and amplified the competitive effects of Ae. albopictus on Ae. triseriatus.