The influence of flow and season upon leaf-litter breakdown in monsoonal Hong Kong streams

Niu, Shuangxia; Dudgeon, David

doi:10.1007/s10750-010-0573-4

Cited by 17 publications

(20 citation statements)

References 41 publications

(56 reference statements)

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“…One alternative reason for the reduced microbial activity in the tropical stream was a short supply of nutrients in stream water (Table ), which can be a crucial N and P pool for microbial decomposers of leaf litter in streams especially on low‐nutrient litter (Rosemond et al ., ; Suberkropp et al ., ; Niu & Dudgeon, ). In our experiment, low microbial activity was reflected by low fungal biomass (A. Bruder et al ., unpubl.…”

Section: Discussionmentioning

confidence: 99%

Litter decomposition in a temperate and a tropical stream: the effects of species mixing, litter quality and shredders

et al. 2013

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Summary The current rapid decline in biodiversity has led to concerns about the consequences for stream ecosystem processes, one of which is the decomposition of leaf litter derived from riparian vegetation. We conducted field experiments in a tropical and a temperate stream to test for the effects of mixing leaf species differing in resource quality on the decomposition of leaf litter and on the colonisation of the litter by leaf‐shredding invertebrates. The effects of litter mixing were minor compared with the effects of litter quality and the presence or absence of shredders. Low shredder abundance in the tropical stream and poor quality of the tropical leaf species, particularly in terms of phosphorus content and toughness, were associated with low decomposition rates in the tropical compared with the temperate stream. This is especially true when considering the 20 °C temperature differences between the two streams. In the presence of shredders, the decomposition rate of a standard litter type, leaves of Alnus glutinosa, was 2.6‐fold faster in the temperate stream, whereas rates were similar when shredders were absent. This indicates that differences in environmental conditions other than temperature had a strong effect. Differences in water chemistry, such as higher concentrations of dissolved nutrients in the temperate stream, might account for this effect. In conclusion, despite a lack of clear effects of litter mixing on decomposition, our results highlight the importance of litter identity and environmental conditions for both microbial and shredder‐mediated litter decomposition, suggesting that changes in riparian vegetation and other stream characteristics will affect stream ecosystems in the face of widespread environmental change.

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Section: Discussionmentioning

confidence: 99%

Litter decomposition in a temperate and a tropical stream: the effects of species mixing, litter quality and shredders

et al. 2013

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“…However, e-flow management decisions need to be based around sustaining natural assemblage structure, and not maximizing diversity of a single group. Among the algae, the linear response of Cocconeis placentula to discharge reduction may have value as indicator for monitoring success of an e-flow implementation program in monsoonal streams based around the rules-of-thumb set out above, although we recommend that any such monitoring include macroinvertebrates as well as diatoms, and might also be combined with process-based measurements that reflect ecosystem functioning (Niu & Dudgeon, 2011b). The information thereby generated could be used to inform adaptive management and thereby refine e-flow allocations for regulated monsoonal streams such as those in Hong Kong.…”

Section: Environmental Flow Allocation Based On Eco-hydrological Relamentioning

confidence: 99%

Responses of epibenthic algal assemblages to water abstraction in Hong Kong streams

2012

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We studied the effects of flow reduction on epibenthic algal assemblages by comparing up-and down-stream reaches of ten Hong Kong streams subject to different degrees of water abstraction during [2007][2008]. Downstream discharge declined by 71 and 54% during the wet and dry seasons, respectively. Algal responses varied seasonally and according to morphological guild and reflecting reductions in discharge and current velocity, or changes in total nitrogen and phosphate, or their combined effects. Significant inter-reach assemblage differences were observed during the both seasons, but wet-season assemblage structure was not directly influenced by any flow-related variable. During the dry season, scouring-tolerant prostrate/adnate diatoms (especially Achnanthes, Cocconeis) were relatively abundant upstream, whereas intolerant stalked (Eunotia, Gomphonema) and mobile diatoms were more numerous downstream. Both low-and high-profile (erect diatoms, Chamaesiphon, Calothrix) guilds were sensitive to changes in nutrients. Low-flow conditions downstream, surprisingly, enhanced algal diversity, and richness. Based on the linear response of Cocconeis (mainly C. placentula) to discharge reduction, we recommend that[65% of dry-season discharge should be maintained in downstream reaches in order to sustain near-natural algal assemblages; 32% of discharge is required to avoid substantial alterations in assemblage structure.

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“…This was despite the fact that in all of these downstream sites current velocity, which is known to be an important driver of LLB (Boulton et al, 2008;Grac ßa et al, 2015;Niu & Dudgeon, 2011), was not systematically greater than at upstream sites (Table S1). …”

Section: Shreddersmentioning

confidence: 82%

“…Bunn & Arthington, 2002;Elosegi & Sabater, 2013). Primarily, the presence of dams on intermittent streams can potentially favour a flow reduction or even a dewatering of streams that consequently could cause the mortality of aquatic organisms and/or a reduction of leaf-litter decomposition (Niu & Dudgeon, 2011). Primarily, the presence of dams on intermittent streams can potentially favour a flow reduction or even a dewatering of streams that consequently could cause the mortality of aquatic organisms and/or a reduction of leaf-litter decomposition (Niu & Dudgeon, 2011).…”

Section: Streams and Rivers Show Natural Longitudinal Variations In Bothmentioning

confidence: 99%

Fishpond dams affect leaf‐litter processing and associated detritivore communities along intermittent low‐order streams

et al. 2017

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Intermittent streams are common and widespread freshwater ecosystems globally. While dams greatly affect the ecology of permanent streams, the extent of their effects on intermittent streams remains largely unknown. The physical and chemical alterations induced by dams could have particularly strong impacts on the functioning of intermittent low‐order streams, especially due to the limitations they place on colonisation of aquatic biota from downstream permanent waters. Leaf‐litter breakdown (LLB) and associated communities (microbes and shredders) were studied to investigate the potential ecological continuum rupture caused by fishpond dams along the longitudinal gradient of intermittent streams. Three to four sites were investigated along three reference (no dam) and three impacted (with a fishpond dam) first‐order intermittent low‐order streams. LLB increased along the longitudinal gradient in all six streams regardless of the presence of dams (from 1.5 to 8.4 fold over <1.5 km distance). This underscores the great variability of low‐order stream functioning even at fine scales. Such upstream to downstream gradients need to be taken into account before investigating the effect of any perturbation using LLB as a functional indicator. Fishponds dams tended to increase LLB downstream, and altered the downstream microbial communities (increase in fungal densities) and shredder assemblages (increase in Gammaridae). The effects of fishpond dams on intermittent stream functioning appeared to be most significant when they were associated with changes in hydrology, that is, when fishponds resulted in permanent flows downstream of dams. Our findings suggest that better management of fishpond dams in order to limit hydrological modifications downstream (for instance, by preventing leaks from the dam) could reduce their impact on ecosystem functioning in intermittent streams.

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The influence of flow and season upon leaf-litter breakdown in monsoonal Hong Kong streams

Cited by 17 publications

References 41 publications

Litter decomposition in a temperate and a tropical stream: the effects of species mixing, litter quality and shredders

Litter decomposition in a temperate and a tropical stream: the effects of species mixing, litter quality and shredders

Responses of epibenthic algal assemblages to water abstraction in Hong Kong streams

Fishpond dams affect leaf‐litter processing and associated detritivore communities along intermittent low‐order streams

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