Abstract
Current ecological research and ecosystem management call for improved
understanding of the abiotic drivers of community dynamics, including
temperature effects on species interactions and biomass accumulation.
Allometric trophic network (ATN) models provide an attractive framework
to study consumer-resource interactions from organisms to ecosystems,
but they rarely consider changes in some key abiotic drivers that affect
e.g. consumer metabolism and producer growth. Here we investigate how
seasonal changes in carrying capacity and light-dependent growth rate of
producers and temperature-dependent mass-specific metabolic rate of
consumers affect ATN model dynamics, namely seasonal biomass
accumulation, productivity and standing stock biomass of different
trophic guilds, including age-structured fish communities. Our
simulations of the complex Lake Constance (LC) food web indicated marked
effects of seasonal abiotic drivers on seasonal biomass accumulation of
different guild groups, particularly among the lowest trophic levels
(autotrophs and invertebrates). While the adjustment of irradiance level
had minor effect, increasing metabolic rate associated with 1–2˚C
temperature increase lead to a marked decline of larval (0-year age)
fish biomass, but to a substantial biomass increase of 2- and 3-year-old
fish that were not predated by ≥4-year-old perch. A gradual temperature
increase of 0.037˚C year–1 observed in LC increased
the productivity of highest trophic levels (i.e., juvenile and adult
fish) by ca. 40–50% over the 100-year simulation period. However, when
looking at biomass distribution and transfer between trophic guilds in
the LC food web, inclusion of seasonal abiotic drivers caused only minor
changes in average standing stock biomasses and productivity of
different trophic guild groups. Our results demonstrate the potential of
introducing seasonal variation in abiotic ATN model parameters to
simulate within-year fluctuations in community dynamics, as well as to
assess potential future community-level responses to ongoing
environmental changes.