Drought-Induced Decreases in Abundance of Emergent Midge Subsidies Are Offset by Increased Body Size in a Prairie Stream

IF 2.8 2区生物学 Q2 ECOLOGY

Freshwater Biology Pub Date : 2025-02-22 DOI:10.1111/fwb.70011

Adam C. Siders, Garrett W. Hopper, Matt R. Whiles, Alexander J. Reisinger, Keith B. Gido

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引用次数: 0

Abstract

Emerging aquatic insects can be an important resource subsidy for a variety of terrestrial consumers, including spiders, birds, bats and lizards. Emergence flux is influenced by a variety of abiotic and biotic variables, such as temperature, drying, and predators and these variables can also control the body size of emergent insects. Despite their importance, these variables can change rapidly during drought conditions as water temperatures rise, surface area decreases and predator densities increase.
During 2018, the Konza Prairie Biological Station experienced a record drought: flow ceased in the lower reaches of Kings Creek for the first time in over 40 years of observation, leaving a series of isolated pools. We studied how the drought affected aquatic insect emergence in 12 of these pools via elevated temperatures, decreased surface area, and concentration of predators (e.g. fishes and crayfish) over a four-week period. We returned in 2020 and sampled emergence in the same pools over 2 weeks under non-drought conditions to compare emergence between drought and non-drought conditions.
We found three overall patterns: (1) rates of areal emergence abundance and biomass (number or mg DM m⁻² d⁻¹) did not differ between drought and non-drought conditions. In contrast, pool-scale emergence abundance, but not biomass (number or mg DM pool⁻¹ d⁻¹), was lower during drought conditions; (2) average midge body size was larger during the drought relative to the non-drought conditions; (3) environmental variables (e.g. temperature, pool surface area, predator biomass) were not predictive of emergence during drought and non-drought conditions.
Fewer, but larger emergent midges (as seen under drought conditions) may represent a higher quality resource for terrestrial consumers than many smaller midges due to increased per-capita energy yield. However, due to the overall decrease in water availability throughout the stream network, the overall emergence flux was concentrated in reaches with remaining water during the drought, making pools emergence subsidy hotspots. Overall, these contrasting responses underscore the complex nature of community responses to shifting climatic conditions.

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来源期刊

Freshwater Biology 生物-海洋与淡水生物学

CiteScore

5.90

自引率

3.70%

发文量

162

审稿时长

2 months

期刊介绍： Freshwater Biology publishes papers on all aspects of the ecology of inland waters, including rivers and lakes, ground waters, flood plains and other freshwater wetlands. We include studies of micro-organisms, algae, macrophytes, invertebrates, fish and other vertebrates, as well as those concerning whole systems and related physical and chemical aspects of the environment, provided that they have clear biological relevance. Studies may focus at any level in the ecological hierarchy from physiological ecology and animal behaviour, through population dynamics and evolutionary genetics, to community interactions, biogeography and ecosystem functioning. They may also be at any scale: from microhabitat to landscape, and continental to global. Preference is given to research, whether meta-analytical, experimental, theoretical or descriptive, highlighting causal (ecological) mechanisms from which clearly stated hypotheses are derived. Manuscripts with an experimental or conceptual flavour are particularly welcome, as are those or which integrate laboratory and field work, and studies from less well researched areas of the world. Priority is given to submissions that are likely to interest a wide range of readers. We encourage submission of papers well grounded in ecological theory that deal with issues related to the conservation and management of inland waters. Papers interpreting fundamental research in a way that makes clear its applied, strategic or socio-economic relevance are also welcome. Review articles (FRESHWATER BIOLOGY REVIEWS) and discussion papers (OPINION) are also invited: these enable authors to publish high-quality material outside the constraints of standard research papers.