Data from: Combining mesocosms with models to unravel the effects of global warming and ocean acidification on a temperate marine ecosystem

Ocean warming and species exploitation have already caused large-scale
reorganization of biological communities across the world. Accurate
projections of future biodiversity change require a comprehensive
understanding of how entire communities respond to global change. We
combined a time-dynamic integrated food web modelling approach (Ecosim)
with previous data from community-level mesocosm experiments to determine
the independent and combined effects of ocean warming and acidification,
and fisheries exploitation, on a well-managed temperate coastal ecosystem.
The mesocosm parameters enabled important physiological and behavioural
responses to climate stressors to be projected for trophic levels ranging
from primary producers to top predators, including sharks. Through model
simulations, we show that under sustainable rates of exploitation,
near-future warming or ocean acidification in isolation could benefit
species biomass at higher trophic levels (e.g., mammals, birds, and
demersal finfish) in their current climate ranges, with the exception of
small pelagic fish. However, under warming and acidification combined
biomass-increases at higher trophic levels will be lower or absent, whilst
in the longer term reduced productivity of prey species is unlikely to
support the increased biomass at the top of the food web. We also show
that increases in exploitation will suppress any positive effects of
human-driven climate change, causing individual species biomass to
decrease at higher trophic levels. Nevertheless, total future potential
biomass of some fisheries species in temperate areas might remain high,
particularly under acidification, because unharvested opportunistic
species will likely benefit from decreased competition and show an
increase in biomass. Ecological indicators of species composition such as
the Shannon diversity index declined under all climate change scenarios,
suggesting a trade-off between biomass gain and functional diversity. By
coupling parameters from multi-level mesocosm food web experiments with
dynamic food web models, we were able to simulate the generative
mechanisms that drive complex responses of temperate marine ecosystems to
global change. This approach, which blends theory with experimental data,
provides new prospects for forecasting climate-driven biodiversity change
and its effects on ecosystem processes.