Influence of leaf miners and environmental quality on litter breakdown in tropical headwater streams

Cionek, Vivian de Mello; Fogaça, Fábio Nascimento Oliveira; Moulton, Timothy P.; Pazianoto, Laryssa H. R.; Landgraf, Guilherme Okuda; Benedito, Evanilde

doi:10.1007/s10750-021-04529-6

Cited by 7 publications

(3 citation statements)

References 98 publications

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“…Most large shredding caddisfly species were extirpated; increases in abundance of the leaf‐mining chironomid Stenochironomus sp. may be supplementing that role (as observed of this genus by de Mello Cionek et al, 2021), but their efficacy as shredders in these streams is uncertain (Carey et al, 2021b). While some taxonomic redundancy is possible, our results suggest that more broadly, NJF stream communities are becoming homogenized with the wider Western Australian landscape, as generalist taxa found across the continent replace specialist, locally endemic taxa.…”

Section: Discussionmentioning

confidence: 99%

Loss of functionally important and regionally endemic species from streams forced into intermittency by global warming

Carey

Chester

Robson

2023

Global Change Biology

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Climate change is altering hydrological cycles globally, and in Mediterranean (med-) climate regions it is causing the drying of river flow regimes, including the loss of perennial flows. Water regime exerts a strong influence over stream assemblages, which have developed over geological timeframes with the extant flow regime.Consequently, sudden drying in formerly perennial streams is expected to have large, negative impacts on stream fauna. We compared contemporary (2016/17) macroinvertebrate assemblages of formerly perennial streams that became intermittently flowing (since the early 2000s) to assemblages recorded in the same streams by a study conducted pre-drying (1981/82) in the med-climate region of southwestern Australia (the Wungong Brook catchment, SWA), using a multiple before-after, control-impact design. Assemblage composition in the stream reaches that remained perennial changed very little between the studies. In contrast, recent intermittency had a profound effect on species composition in streams impacted by drying, including the extirpation of nearly all Gondwanan relictual insect species. New species arriving at intermittent streams tended to be widespread, resilient species including desert-adapted taxa. Intermittent streams also had distinct species assemblages, due in part to differences in their hydroperiods, allowing the establishment of distinct winter and summer assemblages in streams with longer-lived pools. The remaining perennial stream is the only refuge for ancient Gondwanan relict species and the only place in the Wungong Brook catchment where many of these species still persist.The fauna of SWA upland streams is becoming homogenised with that of the wider Western Australian landscape, as drought-tolerant, widespread species replace local endemics. Flow regime drying caused large, in situ alterations to stream assemblage composition and demonstrates the threat posed to relictual stream faunas in regions where climates are drying.

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Section: Discussionmentioning

confidence: 99%

Loss of functionally important and regionally endemic species from streams forced into intermittency by global warming

Carey

Chester

Robson

2023

Global Change Biology

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“…de Mello Cionek et al. (2021) found that they colonised fine‐ and coarse‐mesh bags, that they were an important shredder whose densities correlated with leaf decomposition rates, and that they were an indicator of less‐degraded streams. They also observed that more ‘typical’ shredder taxa (e.g.…”

Section: Discussionmentioning

confidence: 99%

Flow regime change alters shredder identity but not leaf litter decomposition in headwater streams affected by severe, permanent drying

2021

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Climate change is altering hydrologic regimes globally. In the Mediterranean climate region of south‐western Australia (SWA), climate drying has caused many perennial streams to switch to intermittent flow regimes. Shifts in flow regime are expected to alter physical and biological processes in streams, including litter decomposition, which is the basis of detrital food webs. Decomposition of jarrah (Eucalyptus marginata) leaves and associated macroinvertebrates, were measured over 320 days in 2018–19 using leaf bags in four headwater streams in SWA. Two streams retained perennial reaches and two were formerly perennial streams that are now intermittent. Pre‐planned comparisons that formed a partial multiple before–after, control–impact design were used to compare the results to an experiment conducted in 1982–83 in some of the same streams when all were perennially flowing. Both experiments used coarse and fine‐mesh bags containing 10 g of dry leaves. In one perennial stream, coarse bags lost more weight than fine bags at the last sampling time only, when shredding caddisflies arrived on the leaf bags. In the other perennial stream, leaf‐mining chironomids entered fine‐mesh bags and accelerated decomposition so that they lost more weight than the coarse‐mesh bags. There was no difference in weight loss between fine and coarse‐mesh leaf bags in the two intermittent streams. In 2018–19, decomposition was slower in dry reaches of intermittent streams than in perennial reaches. Leaf weight loss increased with the resumption of flow in intermittent streams, so that by the end of the experiment, similar amounts of leaf weight had been lost in intermittent and perennial reaches. Thus, although the temporal pattern of decomposition differed between intermittent and perennial reaches, after 320 days, they had reached a similar endpoint. Over similar experimental duration, mean leaf weight remaining in perennial reaches at the end of the experiment did not differ between the 1982–83 study and 2018–19, showing that leaf decomposition had not changed in reaches that retained perennial flow. As mean leaf weight remaining also did not differ between intermittent and perennial streams in 2018–19, leaf decomposition was robust to flow regime change. However, since 1982–83, these streams have lost populations of shredding caddisflies and stoneflies, which were replaced by other shredders (e.g. leaf mining chironomids Stenochironomus sp.), showing that there was some redundancy amongst shredder species. As climate change progresses, drying flow regimes will become commonplace in Mediterranean (and other) climate regions globally. This study indicates that litter decomposition may be maintained as streams transition to intermittency although shredder species may change. However, the impact of shredding species on leaf decomposition varies amongst studies, so effects of the loss of shredder species sensitive to drying may also vary, and in some cases their loss may substantially alter ecosystem processes.

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“…The degradation of their organic matter is an important part of the aquatic carbon cycle, supporting food and debris chains and ensuring the storage of carbon that was previously sequestered from the atmosphere during the vegetative period. Many studies described leaf breakdown dynamics under different conditions and influencing factors, including variations of salinity, surrounding land use, water depth and species [12][13][14][15][16], but the consequences of aquatic macrophytes loss in terms of reduced organic inputs to support wetland processes and functions are often overlooked. Additionally, aquatic vegetation plays an important role in supporting biodiversity and water quality.…”

Section: Introductionmentioning

confidence: 99%

Aquatic Vegetation Loss and Its Implication on Climate Regulation in a Protected Freshwater Wetland of Po River Delta Park (Italy)

Gaglio

Bresciani²,

Ghirardi³

et al. 2022

Water

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Aquatic vegetation loss caused substantial decrease of ecosystem processes and services during the last decades, particularly for the capacity of these ecosystems to sequester and store carbon from the atmosphere. This study investigated the extent of aquatic emergent vegetation loss for the period 1985–2018 and the consequent effects on carbon sequestration and storage capacity of Valle Santa wetland, a protected freshwater wetland dominated by Phragmites australis located in the Po river delta Park (Northern Italy), as a function of primary productivity and biomass decomposition, assessed by means of satellite images and experimental measures. The results showed an extended loss of aquatic vegetated habitats during the considered period, with 1989 being the year with higher productivity. The mean breakdown rates of P. australis were 0.00532 d−1 and 0.00228 d−1 for leaf and stem carbon content, respectively, leading to a predicted annual decomposition of 64.6% of the total biomass carbon. For 2018 the carbon sequestration capacity was estimated equal to 0.249 kg C m−2 yr−1, while the carbon storage of the whole wetland was 1.75 × 103 t C (0.70 kg C m−2). Nonetheless, despite the protection efforts over time, the vegetation loss occurred during the last decades significantly decreased carbon sequestration and storage by 51.6%, when comparing 2018 and 1989. No statistically significant effects were found for water descriptors. This study demonstrated that P. australis-dominated wetlands support important ecosystem processes and should be regarded as an important carbon sink under an ecosystem services perspective, with the aim to maximize their capacity to mitigate climate change.

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Influence of leaf miners and environmental quality on litter breakdown in tropical headwater streams

Cited by 7 publications

References 98 publications

Loss of functionally important and regionally endemic species from streams forced into intermittency by global warming

Loss of functionally important and regionally endemic species from streams forced into intermittency by global warming

Flow regime change alters shredder identity but not leaf litter decomposition in headwater streams affected by severe, permanent drying

Aquatic Vegetation Loss and Its Implication on Climate Regulation in a Protected Freshwater Wetland of Po River Delta Park (Italy)

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