Combined effects of hydrologic alteration and cyprinid fish in mediating biogeochemical processes in a Mediterranean stream

Rubio‐Gracia, Francesc; Almeida, David; Bonet, Berta; Casals, Frederic; Espinosa, Carmen; Flecker, Alexander S.; García‐Berthou, Emili; Martı́, Eugènia; Tuulaikhuu, Baigal-Amar; Vila‐Gispert, Anna; Zamora, Leopoldo J. Gómez; Guasch, Helena

doi:10.1016/j.scitotenv.2017.05.287

Cited by 8 publications

(7 citation statements)

References 58 publications

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“…Following previous work (Rubio-Gracia et al 2017), we set up a mesocosm experiment that allowed us to control the presence or absence of fish and quantify treatment effects on trophic levels. The experiment was conducted for 4 weeks between June and July 2017.…”

Section: Exclosure/enclosure Mesocosm Experimentsmentioning

confidence: 99%

“…(2) afterwards, 6 Barbus meridionalis were placed into the same cages (enclosure experiment), simulating the high fish density (around 6 individuals per m 2 ) that are typical of well-preserved rivers or in isolated pools when some Mediterranean-climate streams dry down (Rubio-Gracia et al 2017). The 90 barbels used in this experiment (range fork length, FL = 84-115 mm) were previously caught by electrofishing (LR-24 Smith-Root Ltd. 120 V DC-0.6 A) from the reference site (Upstream 1) and transferred to downstream reaches.…”

Section: Exclosure/enclosure Mesocosm Experimentsmentioning

confidence: 99%

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Response of stream ecosystem structure to heavy metal pollution: context-dependency of top-down control by fish

et al. 2022

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The stress-gradient hypothesis predicts that biotic interactions within food webs are context dependent, since environmental stressors can attenuate consumer–prey interactions. Yet, how heavy metal pollution influences the impacts of predatory fish on ecosystem structure is unknown. This study was conducted in the Osor stream (Spain), which features a metal (mainly Zn) pollution gradient. We aimed to determine how the responses of benthic communities to the presence and absence of predatory fish interact with environmental stress and to test whether the top-down control of top predators is context dependent. To address these questions, periphyton biomass and macroinvertebrate densities were determined throughout an exclosure/enclosure mesocosm experiment using the Mediterranean barbel (Barbus meridionalis) as a top predator. The monitoring study showed that metal accumulation in periphyton and macroinvertebrates reflected patterns observed in water. The mesocosm study showed that fish predation effects on larval chironomids were not context-dependent and that periphyton biomass was markedly lower in the presence of fish regardless of metal pollution levels. This strong top-down control on periphytic algae was attributed to the foraging behaviour of fish causing bioturbation. In contrast, the top predator removal revealed grazer-periphyton interactions, which were mediated by heavy metal pollution. That is, periphyton benefitted from a lower grazing pressure in the metal-polluted sites. Together, our results suggest that the top–down control by fishes depends more on functional traits (e.g. feeding behaviour) than on feeding guild, and demonstrate the capacity of top predators to modify anthropogenic stressor effects on stream food-web structure.

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Section: Exclosure/enclosure Mesocosm Experimentsmentioning

confidence: 99%

Section: Exclosure/enclosure Mesocosm Experimentsmentioning

confidence: 99%

Response of stream ecosystem structure to heavy metal pollution: context-dependency of top-down control by fish

et al. 2022

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“…Consequently, experimental exclusions of fish can alter the abundance and dominance of other species, highlighting the role of fish predation on the structuring of freshwater communities (Morin, 1984). Fish have the potential to influence other components of ecosystems by controlling the abundance of important basal resources, affecting the periphyton community structure (Hill et al, 2000) and, consequently, the macroinvertebrate community (Rubio-Gracia et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

“…Properly designed and controlled field experiments are one of the best ways to determine cause and effect relationships among organisms (Kennelly, 1991), and cage experiments with fish have been proven to be effective and provide reliable results (Power, 1990;Rubio-Gracia et al, 2017). Cage experiments may cause artefacts that controls cannot always detect, confounding the results and causing secondary outcomes associated with the cage, like altered algal growth, sedimentation changes due to alterations in hydrodynamics, and the confusion of experimental effects with local-scale patchiness of predators (Connel, 1997).…”

Section: Introductionmentioning

confidence: 99%

Brown trout density effects on the macroinvertebrate and biofilm communities of headwater streams: a cage experiment

Sancha¹,

Roig²,

Aranyó³

et al. 2023

Limnetica

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Salmo trutta is a key species of headwater streams that is able to influence the structure of these ecosystems through predation. Populations of this species are being threatened by climate change and hydrological alteration. In order to understand how their disappearance would affect the ecosystem structure of headwater streams, we used cage experiments to analyse different biofilm and macroinvertebrate structural parameters and the biodiversity of their communities under different trout densities. Due to a heavy rain event, our experiment was destroyed on the 10th day, but the role of trout as stream ecosystemic structure drivers was observed, as multiple parameters were modulated by their presence or absence. In the high-density treatments, a significant reduction in the biomass of macroinvertebrate families that fed on biofilms was observed due to direct predation on them, which caused the biofilms to be more autotrophic. A decrease in brown trout population densities could cause cascading trophic effects on the ecosystem structure of headwater streams.

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“…Specific predictions for Mediterranean climate regions indicate a strong reduction in the mean precipitationwhich would occur as more intense and less frequent rainfall events-and a probable decrease in annual runoff that will lead to reduced river flows (Bangash et al, 2013;Proia et al, 2013;Schneider et al, 2013). In addition, hydrological regime of running waters can be affected by flow regulation through dams and impoundments building (Rubio-Gracia et al, 2017). Moreover, anthropogenic activities can alter river banks causing riparian forest modifications and consequentially altering the quantity and quality of light potentially reaching riverbeds (Dal Sasso et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Water Flow and Light Availability Influence on Intracellular Geosmin Production in River Biofilms

et al. 2020

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Hydro-morphological alterations in water bodies caused by climate change and human activities affects the ecosystem functioning and generate important water quality problems. Some of these alterations can generate an increase in cyanobacterial blooms, which are associated with the appearance of bad taste and odorous compounds such as geosmin. The factors that trigger their production are still unclear, and this inability to predict geosmin episodes provokes economic problems for water supply companies. This study aims to evaluate the effects of water flow and light availability on biofilm development and intracellular geosmin formation. A mesocosm experiment was performed between February-April, 2019. The mesocosms were a set of 10 outdoor 3 m long flumes, with a continuous water supply from the Ter river (Catalonia, NE Spain). Two light intensities were established: natural light and light reduced to 80%, combined with five gradual water flows from 0.09 to 1.10 L/s. Water samples were taken to analyze nutrients, and biofilm samples, to analyze geosmin concentration, chlorophyll a and the community. Geosmin in biofilm was detected in those treatments in which Oscillatoria sp. appeared. The concentration of intracellular geosmin was higher at lower water flows (0.09 and 0.18 L/s), and the highest (2.12 mg/g) was found in the flume with the lowest water flow (0.09 L/s) and irradiation (20%). This flume was the one that presented a greater concentration of Oscillatoria sp. (21% of the community). It stands out that, when geosmin in biofilm was found, the dissolved inorganic nitrogen and soluble reactive phosphorus ratio decreased, from an average of 417:1 to 14:1. This was mainly due to an increase in inorganic phosphorus concentration generated by a change in the nutrient uptake capacity of the community's biofilm. The results obtained in this study indicated the potential implications for stream ecosystem management to control geosmin appearance. Likewise, they could be used as an early warning system, establishing that in times of drought, which lead to a general decrease in river water flow, the situation could be optimal for the appearance and development of geosmin producing cyanobacteria in low-flow areas near the river banks.

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Combined effects of hydrologic alteration and cyprinid fish in mediating biogeochemical processes in a Mediterranean stream

Cited by 8 publications

References 58 publications

Response of stream ecosystem structure to heavy metal pollution: context-dependency of top-down control by fish

Response of stream ecosystem structure to heavy metal pollution: context-dependency of top-down control by fish

Brown trout density effects on the macroinvertebrate and biofilm communities of headwater streams: a cage experiment

Water Flow and Light Availability Influence on Intracellular Geosmin Production in River Biofilms

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