Variability of water temperature may influence food-chain length in temperate streams

Hette-Tronquart, Nicolas; Roussel, Jean‐Marc; Dumont, Bernard; Archaimbault, Virginie; Pont, Didier; Oberdorff, Thierry; Belliard, Jérôme

doi:10.1007/s10750-013-1613-7

Cited by 15 publications

(11 citation statements)

References 50 publications

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“…We believe this is due to the fact that such sites were not only constrained in spatial dimensions but were also less stable and more stressful than their larger perennial counterparts. This is corroborated by past work illustrating a negative effect of environmental instability on FCL in streams (Parker and Huryn , Marty et al , Sabo et al , Hette‐Tronquart et al ) and highlights the need to consider how flow loss may affect other food web controls (Sabo et al ) when using existing information to make projections. Taken together, this indicates that stream habitats that are already compressed relative to their full potential may respond more strongly to flow loss than evidence from perennial streams might suggest and further implies that food webs in disturbed streams are ‘sized’ to minimum low flows rather than average flow conditions.…”

Section: Discussionsupporting

confidence: 75%

“…Although we demonstrate a strong ecosystem size effect here, it is important to recognize that this does not contradict prior assertions that environmental instability can exert control on food web structure in streams (Parker and Huryn , Marty et al , McHugh et al , Sabo et al , Hette‐Tronquart et al ). To the contrary, it is well established that environmental harshness and instability typically increase with reductions in habitat size (Saunders et al ), particularly within a drying rivers context (Dewson et al ).…”

Section: Discussionsupporting

confidence: 67%

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Habitat size influences food web structure in drying streams

et al. 2014

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Biodiversity in running waters is threatened by an increased severity and incidence of low‐flow extremes resulting from global climate change and a growing human demand for freshwater resources. Although it is unknown how and to what extent riverine communities will change in the face of these threats, considerable insight will be gained from efforts aimed at quantifying habitat size‐related controls on the trophic relationships among taxa in streams experiencing extreme flow loss. Here we report on a detailed space‐for‐time survey of replicate stream food webs sampled along the perennial‐ to‐drying continuum in each of fourteen different intermittent South Island, New Zealand streams. We quantified several structural attributes of food webs at fifty‐eight sites, including two taxonomically‐based metrics (web size, predator:prey ratio) and three stable isotope‐based metrics (food chain length [FCL], trophic area, δ13C range); we also quantified habitat size‐, disturbance‐, and resource‐related covariates at each site. Food web structure varied widely across sample sites within and across study streams and much of this variation was explained by habitat size. Consistent with our predictions, we found that food webs became smaller (ca 30 to ca 15 taxa, ca 20‐fold reduction in stable isotope‐based trophic area) and shorter (maximum trophic position [FCL] from 4.1 to 2.0, 25% reduction in predator:prey ratio) as we moved from the largest to smaller habitats. These results, and a comparison of our findings with those from a similar assessment conducted in perennial streams, suggest that there are perturbation thresholds which may trigger food web collapse when exceeded, and further imply that food webs may ultimately be ‘sized’ to minimum flows rather than average flow conditions. Our work provides a basis for making general predictions about how habitat contraction, and flow loss in particular, may affect communities and additionally provides insight on mechanisms warranting further attention.

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Section: Discussionsupporting

confidence: 75%

Section: Discussionsupporting

confidence: 67%

Habitat size influences food web structure in drying streams

et al. 2014

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“…For example, McHugh et al (2015) found that while food chain length was lower in fishless reaches overall, macroinvertebrate-dominated food chains contributed to an overall relationship between habitat size and trophic diversity in intermittent streams. Further, Hette-Tronquart et al (2013) showed that much of the difference in food chain length between streams with differing variability in water temperature was due to the trophic position of filter feeders and shredders. Finally, in their meta-analysis of determinants of food chain length, Takimoto and Post (2013) found positive effects of ecosystem size on trophic diversity in the macroinvertebrate-dominated pitcher plant ecosystems studied by Baiser et al (2011).…”

Section: Introductionmentioning

confidence: 99%

Flow intermittency influences the trophic base, but not the overall diversity of alpine stream food webs

2019

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Alpine streams can exhibit naturally high levels of flow intermittency. However, how flow intermittency in alpine streams affects ecosystem functions such as food web trophic structure is virtually unknown. Here, we characterized the trophic diversity of aquatic food webs in 28 headwater streams of the Val Roseg, a glacierized alpine catchment. We compared stable isotope (δ13C and δ15N) trophic indices to high temporal resolution data on flow intermittency. Overall trophic diversity, food chain length and diversity of basal resource use did not differ to a large extent across streams. In contrast, gradient and mixing model analysis indicated that primary consumers assimilated proportionally more periphyton and less allochthonous organic matter in more intermittent streams. Higher coarse particulate organic matter (CPOM) C:N ratios were an additional driver of changes in macroinvertebrate diets. These results indicate that the trophic base of stream food webs shifts away from terrestrial organic matter to autochthonous organic matter as flow intermittency increases, most likely due to reduced CPOM conditioning in dry streams. This study highlights the significant, yet gradual shifts in ecosystem function that occur as streamflow becomes more intermittent in alpine streams. As alpine streams become more intermittent, identifying which functional changes occur via gradual as opposed to threshold responses is likely to be vitally important to their management and conservation.

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“…For example, eutrophication of coastal waters is an increasing problem in many estuaries of the world and is often viewed as being driven solely by increases in nutrient loading, but in fact spatial patterns in eutrophic conditions can be influenced by water temperature because the rate of chemical processes that lead to entropic conditions scale with water temperature (Lomas & Glibert, 1999;Miller & Harding, 2007). Primary production of organic matter and respiration rates increase with higher temperatures, which leads to higher oxygen demand in the water column under sufficient light and nutrient conditions (Alcântara et al, 2010;Demars & Manson, 2013;Hette-Tronquart, Roussel, Dumont, Archaimbault, & Pont, 2013;Lomas & Glibert, 1999). In contrast, the solubility of oxygen in water decreases as temperature increases.…”

Section: Introductionmentioning

confidence: 99%