Biomassess of functional groups and ecosystem parameters predicted by ecosim models of Lake Dianchi

Understanding the relative importance of multiple stressors is valuable to
prioritize conservation and restoration measures. Yet, the effects of
multiple stressors on ecosystem functioning remain largely unknown in many
freshwaters. Here, we provided a methodology combining ecosystem modelling
with linear regression to disentangle the effects of multiple stressors on
matter flow, an important ecosystem function. Treating a shallow lake as
the model ecosystem, we simulated matter flow dynamics during 1950s-2010s
with different combinations of stressors by Ecopath with Ecosim (EwE)
modelling, and determined the relative importance of each stressor by
generalized linear mixed models. We found that matter flow of the lake
food web was highly dynamic, attributing to effects of multiple
anthropogenic stressors. Biological invasion played the strongest role in
driving the matter flow dynamics, followed by eutrophication, while
biomanipulation (i.e. phytoplankton control by planktivorous fish
stocking) was of little importance. Eutrophication had a stronger role on
primary producers, pelagic food chain and top predators, while biological
invasion on consumers in the middle of food chains. The former was more
important in driving the quantity of matter flow, while the latter on
trophic transfer efficiencies. Scenario forecasting showed that reducing
nutrients contents could largely shape the matter flow pattern, while
biomanipulation had little effect. Our findings provided new insights into
understanding the mechanistic links between anthropogenic stressors and
ecosystem functioning by combining ecosystem modelling with linear
regression.