Leah M. Domine

TL;DR: This is the first global quantitative synthesis on under-ice lake ecology, including 36 abiotic and biotic variables from 42 research groups and 101 lakes, examining seasonal differences and connections as well as how seasonal differences vary with geophysical factors.

TL;DR: A global compilation of aquatic animal nutrient excretion rates is presented, which represents valuable data for testing the predictions of important frameworks such as the Metabolic Theory of Ecology (MTE) and ecological stoichiometry (ES).

TL;DR: A method that could be used by lake managers to identify lakes that have an ecological history close to the clear-turbid regime threshold is demonstrated; such lakes might more easily be returned to a clear-water state through biomanipulation.

TL;DR: Examination of hydroclimatic data for the region over the last century suggests that natural forcings on lake ecology have diminished in their importance as human management of the lake increased in the mid-1900s.

Abstract: Shallow lakes process large amounts of carbon (C) via gross primary production (GPP) and respiration (R), but C fluxes are highly variable among lakes. We used a two-prong approach to determine whether C fluxes differed between two alternative stable states observed in shallow lakes. First, we used a replicated whole-lake experiment where we manipulated fish densities in four experimental lakes to induce shifts from the phytoplankton-dominated state (turbid state) to a submersed macrophyte-dominated state (clear state), and determined whether whole-lake GPP, R, and net aquatic production (NAP) changed in response to the manipulation. We also compared lake metabolism in the four experimental lakes to four lakes in a turbid state and four lakes in a clear state. Second, we used sediment cores from 68 shallow lakes to test whether modern burial rates of organic C differed between lakes in clear and turbid states. Biomanipulation in the experimental lakes reduced abundance of fish and phytoplankton and increased abundance of aquatic invertebrates and submerged macrophytes. However, there was no significant change in GPP, R, or NAP. Similarly, GPP, R, and NAP did not differ among experimental lakes, turbid-state lakes, or clear-state lakes. Lastly, organic C burial in sediments did not differ between lakes in clear vs. turbid states, though variability among sites was high. High light and nutrient availability facilitate rapid transitions between two alternative groups of competing, rapidly growing primary producers in shallow lakes. These characteristics facilitate relatively uniform C fluxes at the ecosystem scale despite substantial differences in community structure.