Conclusion
The present study showed that algal growth rate, biomass production, and
elemental contents varied depending on the leaf litter leachates from
different tree species, due not only to differences in N and P
concentrations but also to those of micronutrients. These results
suggest that the stoichiometry and composition of leaf litter leachate
can cause substantial changes not only in algal fitness and primary
production, but also in mass transfer from algae to herbivores. Although
we conducted this study using only a single algal species, the responses
to the changes in leaf litter leachate may differ between algal species
and other heterotrophic organisms that utilize organic matter in leaf
litter leachate. This possibility is worth investigating in future
studies, as the effects of the change and succession in the surrounding
vegetation may have extended to the composition of the entire community
in the freshwater ecosystems. In this study, we investigated the
short-term and direct effects of leaf litter using leaf litter leachate
for 7 days of incubation. In nature, the effects of leaf litter on
aquatic ecosystems may last longer through decomposition in soils and
sediments. Therefore, to fully understand the effects of vegetation
changes on the aquatic community, long-term monitoring studies are
needed in aquatic ecosystems where the catchment vegetation has been
changed.