Turning summer into winter: nutrient dynamics, temperature, density dependence and invasive species drive bioenergetic processes and growth of a keystone coldwater fish

A combination of global changes such as species invasions, climate change and nutrient pollution have altered ecosystems, food webs the bioenergetic processes that control growth. These are especially pronounced in freshwater ecosystems often lead to rapid variation fish growth dependent services fishery yield. Understanding mechanisms driving responses environmental is important for interpreting past dynamics sustainably managing ecosystems. This study uses integrated bioenergetics modeling understand how dynamics, invasions changing temperatures keystone pelagic whitefish Coregonus wartmanni Lake Constance, Germany from 1925 2020. Growth was modeled by allowing covariates alter temperature-dependent consumption, while size-specific metabolism varied only with temperature. Consumption increased strongly a maximum phosphorous, this effect stronger when intraspecific competition (measured biomass) low. Increasing biomass reduced under mesotrophic conditions, but had no oligotrophic conditions. In contrast, increasing invasive three-spined stickleback Gasteosteus aculeauts predicted reduce even The invasion has effectively turned summer into winter whitefish, older ceasing grow younger losing up 10% their body weight during normal growing season subsequent years. Warming further due stickleback, which would zooplankton availability already low yields. results demonstrate importance considering biotic interactions synergistic effects studies, well value mechanistic based models understanding effects. Similar ecosystem likely within across can help support informed management.