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Abstract Many ecosystems receive resource subsidies that affect productivity and food webs. Ecosystem subsidies vary in quantity, quality, and timing, and effects are often mediated by environmental factors, including temperature. Deposition of periodical cicada carcasses into ponds represents a large, high‐quality, infrequent subsidy. Cicadas emerge in massive numbers every 17 yr, and many individuals die and fall into aquatic ecosystems. As climate warms, future cicada subsidies may enter warmer ponds. We conducted a mesocosm experiment with a factorial design to examine the effects of cicada carcasses and elevated (~ 2.6°C) temperature on the growth and development of tadpoles of a common frog,Hyla chrysoscelis. Carcasses and warming each increased frog size at metamorphosis and shortened the time to metamorphosis, and the effects of cicadas and warming were additive for both traits. Mass at metamorphosis was largest and time to metamorphosis shortest with carcass addition and warmed temperature, whereas mass at metamorphosis was smallest and time to metamorphosis longest under ambient temperature without carcasses. Carcasses greatly increased algae biomass (periphyton and phytoplankton), possibly accounting for faster development and larger size of frogs. Warming did not increase standing algal biomass, but increased primary production, possibly increasing food supply for, and growth rates of, tadpoles. Our results show that a large, high‐quality, infrequent subsidy strongly affects pond amphibians, and effects are additively enhanced by warming. Because adult frogs migrate to land, live for several years, and return to their natal pond to breed, a cicada carcass subsidy may mediate reciprocal resource fluxes between land and ponds for several years. 

Many high school students learn about nutrient cycling during biology, environmental science, and agriculture classes. These lessons often focus on soil and plants, and nutrient cycling is usually taught independently from climate change. Scientists know that animals, including fish, can have strong effects on nutrient cycling (i.e., nitrogen and phosphorus) in ecosystems. Additionally, research has shown that nitrogen and phosphorus excretion rates of animals increase with water temperatures. We worked with high school students to design and conduct nutrient excretion experiments using common fish (zebrafish) to explore the impact of climate change on nutrient cycling. This allowed students to have hands-on laboratory experience. In 2021, we worked with students participating in a residential summer program in Georgia. Meanwhile, in 2022, students enrolled in the local high school visited the university campus on two occasions to participate in the experiments, and we once again worked with students in Georgia. Students from all three groups showed an increased understanding of the role of animals in nutrient cycling and ways climate change may impact these processes, despite variable results from the excretion experiments. Students also showed increased understanding of science processes and were more likely to feel like part of the science community. We believe that these experiments can be done in high school classrooms to expand students’ understanding of the scientific process, nutrient cycling, and climate change. 

Abstract Trophic transfer efficiency (TTE) is usually calculated as the ratio of production rates between two consecutive trophic levels. Although seemingly simple, TTE estimates from lakes are rare. In our review, we explore the processes and structures that must be understood for a proper lake TTE estimate. We briefly discuss measurements of production rates and trophic positions and mention how ecological efficiencies, nutrients (N, P) and other compounds (fatty acids) affect energy transfer between trophic levels and hence TTE. Furthermore, we elucidate how TTE estimates are linked with size-based approaches according to the Metabolic Theory of Ecology, and how food-web models can be applied to study TTE in lakes. Subsequently, we explore temporal and spatial heterogeneity of production and TTE in lakes, with a particular focus on the links between benthic and pelagic habitats and between the lake and the terrestrial environment. We provide an overview of TTE estimates from lakes found in the published literature. Finally, we present two alternative approaches to estimating TTE. First, TTE can be seen as a mechanistic quantity informing about the energy and matter flow between producer and consumer groups. This approach is informative with respect to food-web structure, but requires enormous amounts of data. The greatest uncertainty comes from the proper consideration of basal production to estimate TTE of omnivorous organisms. An alternative approach is estimating food-chain and food-web efficiencies, by comparing the heterotrophic production of single consumer levels or the total sum of all heterotrophic production including that of heterotrophic bacteria to the total sum of primary production. We close the review by pointing to a few research questions that would benefit from more frequent and standardized estimates of TTE in lakes. 

Understanding controls on primary productivity is essential for describing ecosystems and their responses to environmental change. Lake primary production is strongly controlled by inputs of nutrients and colored dissolved organic matter. While past studies have developed mathematical models of this nutrient-color paradigm, broad empirical tests of these models are scarce. We compiled data from 58 diverse and globally distributed and mostly temperate lakes to test such a model and improve understanding and prediction of the controls on lake primary production. These lakes varied widely in size (0.02-2300 km2), pelagic gross primary production (20-8000 mg C m-2 d-1), and other characteristics. The data package includes high-frequency dissolved oxygen, water temperature, wind speed, and solar radiation data as well as daily estimates of GPP and ER derived from those data. In addition, the data package includes median in-lake and stream concentrations of dissolved organic carbon and total phosphorus for a subset of 18 of those lakes.