Data from: Terrigenous subsidies in lakes support zooplankton production mainly via a green food chain and not the brown food chain

Terrestrial organic matter (t-OM) has been recognized as an important
cross-boundary subsidy to aquatic ecosystems. However, recent evidence has
shown that t-OM contributes little to promote secondary production in
lakes because it is low quality food for aquatic consumers. To resolve
this conflict, we performed a field experiment using leaf litter as t-OM.
In the experiment, we monitored zooplankton biomass in enclosures with and
without addition of leaf litter under shaded and unshaded conditions and
assessed food web changes with stable isotope analyses. We then examined
whether or not leaf litter indeed stimulates lake secondary production
and, if it does, which food chain, the detritus-originated food chain
(“brown” food chain) or the algae-originated food chain (“green” food
chain), contributes more to this increase. Analyses with stable isotopes
showed a substantial importance of t-OM in supporting the secondary
production under ambient lake conditions. However, addition of the leaf
litter increased the zooplankton biomass under unshaded conditions but not
under shaded conditions. We found that phosphorus was leached from leaf
litter at much faster rate than organic carbon and nitrogen despite its
low content in the leaf litter.  These results showed that leaf
litter stimulated the increase of zooplankton biomass mainly through the
green food chain rather than through the brown food chain, because the
leaf litter supplied limiting nutrients (i.e., phosphorus) for primary
producers. Our results indicate that the functional stoichiometry of the
subsidized organic matter plays a crucial role in determining the relative
importance of brown and green food chains in promoting production at
higher trophic levels in recipient ecosystems.