Biomass distribution of fishes and mussels mediates spatial and temporal heterogeneity in nutrient cycling in streams

Hopper, Garrett W.; Gido, Keith B.; Vaughn, Caryn C.; Parr, Thomas B.; Popejoy, Traci; Atkinson, Carla L.; Gates, Kiza K.

doi:10.1007/s00442-018-4277-1

Cited by 27 publications

(33 citation statements)

References 69 publications

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“…Although crayfish stoichiometry may vary during base-flow conditions, we predict that nutrients controlled by crayfishes may be important to ecosystem functions, including microbial respiration and leaf decomposition in isolated pools dominated by this group (Rosemond, Pringle, Ramírex, Paul, & Meyer, 2002). Future work should focus on interactions among groups within whole communities to understand their influence on nutrient cycling Hopper et al, 2018). Regardless, our study contributes evidence that the relative dominance of broad taxonomic groups (e.g.…”

Section: F I G U R Ementioning

confidence: 80%

“…crustaceans or fishes) may have a prominent influence on stream nutrient dynamics and food web interactions, especially during periods of drought. Future work should focus on interactions among groups within whole communities to understand their influence on nutrient cycling Hopper et al, 2018).…”

Section: N Demand By Epilithic Biofilms and Macroconsumer Excretionmentioning

confidence: 99%

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Biomass loss and change in species dominance shift stream community excretion stoichiometry during severe drought

et al. 2019

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1. Animals contribute significantly to nutrient cycling through excretion, but most studies consider their effects under relatively benign abiotic conditions. Disturbances such as drought may alter animals' nutrient contributions through shifts in species composition and biomass. Headwater streams are particularly vulnerable to extreme climate events and thus might show rapid changes in stream biota and their ecosystem effects.2. We tested how biomass and subsequent ecosystem effects (nutrient cycling) of an intermittent prairie stream community changed during a drought. We quantified the biomass and contributions to nutrient cycling for assemblages comprising fishes, crayfish, and tadpoles in 12 isolated pools over 3 months encompassing the harshest drought on record for Kings Creek, KS, U.S.A. We predicted that macroconsumer biomass would decline with pool surface area and that differences in macroconsumer biomass and taxonomic composition would lead to different contributions of pool assemblages to nutrient cycling.3. The biomass of pool assemblages declined with decreasing pool size, a pattern apparently driven by mortality, emigration, or metamorphosis. We also observed a change in assemblage structure of drying pools during drought relative to pool size, shifting dominance toward species with more drought-resistant traits.Accordingly, assemblage nitrogen (N) excretion rates declined as pool biomass was reduced, leading to a 58% reduction in N available to epilithic biofilms. Phosphorus (P) excretion rates declined from June to July, but increased in August, as species with high P excretion rates maintained similar proportional biomass and biomass of a non-native fish increased. Molar N:P of pool assemblage excretion declined significantly throughout the drought and coincided with loss of southern redbelly dace (Chrosomus erythrogaster: Cyprinidae). 4. Animal-mediated nutrient cycling was altered by the loss of biomass and stoichiometric traits of taxa that differed in their occurrences and ability to tolerate abiotic conditions during drought. Elevated availability of dissolved N in isolated pools may increase N uptake rates by biofilms during drought conditions, indicating the importance of N excreted by aggregated macroconsumers, especially those with S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section. How to cite this article: Hopper GW, Gido KB, Pennock CA, et al. Biomass loss and change in species dominance shift stream community excretion stoichiometry during severe drought.

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Section: F I G U R Ementioning

confidence: 80%

Section: N Demand By Epilithic Biofilms and Macroconsumer Excretionmentioning

confidence: 99%

Biomass loss and change in species dominance shift stream community excretion stoichiometry during severe drought

et al. 2019

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“…Within these years, maximum water temperatures recorded in these rivers for each year varied from 23 to 35°C. Hopper et al () observed temperatures from 29.7 to 32.4°C in the Glover River in 2016. Temperatures of 40°C and diel temperature swings of 8°C are not uncommon within Oklahoma rivers (Farless & Brewer, ; Matthews & Zimmerman, ).…”

Section: Discussionmentioning

confidence: 99%

“…Mussels provide many ecosystem services as well; their biofiltration and nutrient capacitance are regulatory services that promote ecosystem stability for all aquatic organisms (Vaughn, 2018;Vaughn & Hoellein, 2018). The overlap of fish and mussel assemblages during low-water periods has additive effects on nutrient cycling (Hopper et al, 2018). Thus, the paired conservation of these assemblages is beneficial to stream ecosystems and the humans that rely on these streams.…”

Section: Discussionmentioning

confidence: 99%

Freshwater mussels increase survival of largemouth bass (Micropterus salmoides) in drying pools

DuBose

Ashford

Vaughn

2019

Ecology of Freshwater Fish

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Between global climate change and anthropogenic water needs, freshwater systems are becoming more intermittent, stressing organisms adapted to perennial waters. Drought‐induced intermittency concentrates aquatic organisms into drying pools. These pools represent refugia from desiccation but apply other stressors, such as extreme temperatures and increased competition for dwindling resources. In the Southern United States, fishes and freshwater mussels are often concentrated together in drying pools during seasonal, summer droughts. This can result in increased competition for food among invertivorous fish, but also increased food abundance for these fish because mussels increase macroinvertebrate abundance. Further, since mussels require fish as hosts for their ectoparasitic larval phase, glochidia, competition with their host during this biologically active time is detrimental to mussels. We conducted an experiment to examine the effects of freshwater mussels on trophic resources and fish survival in drying pools. We stocked mesocosms with juvenile largemouth bass that were infected or uninfected with glochidia and tracked abiotic conditions, trophic resources and fish survival for 10 days. We found that fish survived longer in the presence of adult mussels, regardless of their infection status. We suspect that prey items supplemented by adult freshwater mussels increased the survival of fish. Thus, the presence of adult mussels and the resources that increase in their presence potentially mitigate stress to fish in “ecological crunch times.” By conserving mussels, fish populations might withstand droughts more easily.

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“…For the K3 dry riffle we laid out 10 transects across the dry mussel bed and identified shells from 14 quadrats across each transect. We used species-specific, length-soft tissue dry mass regression equations (Hopper et al, 2018) to calculate the soft tissue mass of each mussel. We calculated areal nutrient pulses (µg L −1 m −2 ) released to the river as a consequence of mussels dying as the product of nutrients released by decomposing mussel tissue to the water column in the mesocosm at sampling day 4 (µg L −1 g −1 ) by the biomass loss of mussels at a site on an FIGURE 3 | Ambient concentrations of NH 4 -N (µg L −1 ; A), SRP (µg L −1 ; B), water column chlorophyll a concentrations (µg L −1 ; C) and benthic chlorophyll a concentrations (µg cm −2 ; D) in control, live mussel, and dead mussel treatments.…”

Section: Scaling Up: Short and Long-term Nutrient Releases Following mentioning

confidence: 99%

Drought-Induced, Punctuated Loss of Freshwater Mussels Alters Ecosystem Function Across Temporal Scales

et al. 2019

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Punctuated, mass mortality events are increasing for many animal taxa and are often related to climatic extremes such as drought. Freshwater mussels are experiencing increased mass mortality events linked to hydrologic drought. Because mussels play important functional roles in rivers it is important to understand the ecosystem effects of these die-offs. Here, we address how mass mortality events of mussels caused by drought may impact stream ecosystem function. We first present a conceptual model, based on the literature, of how mussel mass mortality should affect different ecosystem functions across various ecological time scales, from hours to decades. Next, we highlight two case studies of drought-linked, mussel-mass mortality events from rivers in the southern U.S. We then present the results of an experiment we performed quantifying the ecosystem effects of a punctuated mussel die-off. Finally, we combine our experimental results with field data from a recent mussel die-off to predict how mussel losses will influence ecosystem function. Based on the presented case studies, our mesocosm experiment, and our extrapolated nutrient pulse due to a mussel die-off, we conclude that stream ecosystems are extensively altered following mussel mass mortality events. Mussel loss is governed by drought severity, location within the river network, and species-specific drought tolerances. In the short term, decomposing carrion from mussel die-offs releases a large pulse of nutrients into the water which stimulates food web productivity. In the long term, the overall loss of mussel biomass, and the loss of functional traits as more sensitive species decline, leads to decreases in ecosystem function which may take decades to recover. Drought and human demand for water will make mussel die-offs more likely in the future and it is unlikely that drought sensitive species will recover without changes in water management and restoration of populations through mussel propagation. Our research provides an example of how the loss of an abundant, long-lived organism has cascading, and long-term impacts on ecosystems.

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Biomass distribution of fishes and mussels mediates spatial and temporal heterogeneity in nutrient cycling in streams

Cited by 27 publications

References 69 publications

Biomass loss and change in species dominance shift stream community excretion stoichiometry during severe drought

Biomass loss and change in species dominance shift stream community excretion stoichiometry during severe drought

Freshwater mussels increase survival of largemouth bass (Micropterus salmoides) in drying pools

Drought-Induced, Punctuated Loss of Freshwater Mussels Alters Ecosystem Function Across Temporal Scales

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