Foodweb structure in a tropical Asian forest stream

Mantel, Sukhmani; Salas, M.C.; Dudgeon, David

doi:10.1899/0887-3593(2004)023<0728:fsiata>2.0.co;2

Cited by 95 publications

(125 citation statements)

References 80 publications

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“…This implies that the relative size between predator and prey, rather than prey species, is the decisive factor that determines prey choice, an observation also made by Woodward (2001) with regard to the foodweb of an English stream. A wide overlap of the diets of fish, shrimps and larger insects is also recorded from a Southern Chinese stream (Mantel et al 2004). Omnivory thus applies in its widest sense: everything that can mechanically be tackled and is physiologically acceptable (i.e.…”

Section: General Omnivorymentioning

confidence: 99%

Omnivory and resource - sharing in nutrient - deficient Rio Negro waters: stabilization of biodiversity?

Walker

2009

Acta Amaz.

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Amazonian biodiversity is notorious, this is also valid for the fauna of the mineral-deficient waters of the Rio Negro System. Some 25 years of research on the benthic fauna of Central Amazonian streams resulted in species-rich foodwebs with a high degree of omnivory within dense animal communities. To exemplify the taxonomic range of omnivorous consumers, the detailed resource spectra of 18 consumer species, including Protozoa (2 species), Platyhelminthes (1 species), insects (2 species), fish (6 species) and shrimps (Decapoda, 7 species), associated primarily with the benthic habitats of Rio Negro tributaries, are presented. Special features of omnivory are characterized, and the importance of litter-decomposing fungi as essential energy input into the foodwebs is documented. It is shown that general omnivory -diverse omnivore consumers sharing most of the resource types-is a prevalent feature. The relevance of this general omnivory for the maintenance of biodiversity is discussed.

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Section: General Omnivorymentioning

confidence: 99%

Omnivory and resource - sharing in nutrient - deficient Rio Negro waters: stabilization of biodiversity?

Walker

2009

Acta Amaz.

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“…Evidence from global studies indicates high variability in shredder occurrence and in breakdown rates across tropical sites (Boyero et al, 2012(Boyero et al, , 2015, which corroborates contrasting results obtained in tropical regions. A growing body of evidence emphasizes the importance of algal carbon in tropical food webs of forested small streams (Salas and Dudgeon, 2001;Mantel et al, 2004;Brito et al, 2006;Li and Dudgeon, 2008;Lau et al, 2009;Neres-Lima et al, 2016;Brett et al, 2017) and it has been claimed that the contribution of macroinvertebrate shredders to leaf breakdown is small in certain tropical running waters due their scarcity (Dudgeon and Wu, 1999;Dobson et al, 2002;Gonçalves et al, 2006bGonçalves et al, , 2007Ardón and Pringle, 2008;Alvim et al, 2015). On the other hand, there is contrary evidence of high diversity and abundance of macroinvertebrate shredders, high secondary production and importance on leaf breakdown (Cheshire et al, 2005;Camacho et al, 2009;Yule et al, 2009;Encalada et al, 2010;Masese et al, 2014;Tonin et al, 2014;Andrade et al, 2017;Neres-Lima et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Relationships of shredders, leaf processing and organic matter along a canopy cover gradient in tropical streams

2017

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Terrestrial allochthonous organic matter represents a structuring element and an important source of energy and carbon to fauna in small forested streams. However, the role of this matter as a food resource for benthic macroinvertebrates, and consequently, for shredders and their performance in riverine processes, is not clear in low-order tropical streams. Aiming to investigate the relationship between shredders and leaves, we analyzed along a gradient of 8-93% canopy cover biomass and abundance of shredders, accumulated leaves and breakdown rates of local leaves to verify if these parameters were related to shade conditions and to each other. Three hypotheses were tested: i) shredder biomass, accumulated leaves and breakdown rates are related to canopy cover and exhibit higher values in shaded sites; ii) shredder biomass is positively related to accumulated leaves and breakdown rates; and iii) due to the relatively large body size of the important shredders, the association of shredders with leaves and importance to leaf processing should be better expressed in terms of guild biomass than abundance. Shredder biomass varied between 846 and 1506 mg dry mass (DM) m -2 and accumulated leaves varied between 479 and 1120 g ash free dry mass (AFDM) m -2 across sites. Leaf breakdown rate (k), the only measured variable that varied significantly among sites, varied between -0.0015 and -0.0238 day -1 . Neither shredder biomass nor leaf biomass were associated with the shading gradient. On the other hand, shredder abundance and biomass, mainly represented by Triplectides (Trichoptera, Leptoceridae), was positively related to accumulated leaves within sites and to breakdown rates assessed by leaf packs. Leaf breakdown, as assessed by the experimental leaf packs, was associated with shredder biomass, but not with shredder abundance. This result suggests that macroinvertebrates are important for leaf detritus processing and that their biomass reflects their activity, presumably because it is related to their secondary production and perhaps non-consumptive action. Their activity was observed at the scale of leaf packs and not at the scale of variation in canopy cover because apparently canopy did not modulate availability of leaves, which were apparently not limiting to the shredders.

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“…Analysis of carbon and nitrogen stable isotopes (d 13 C and d 15 N) has been increasingly applied in studies of aquatic food webs because of their capacity to reveal food assimilation, and thus actual energy transfer, rather than merely ingestion as indicated by gut-content analysis or feeding observations (e.g., Yoshioka et al 1994;Hall et al 2001;O'Reilly et al 2002;Mantel et al 2004;Li and Dudgeon 2008). Stable isotopes of samples preserved in formalin, ethanol, and formalin-ethanol (fixation in formalin followed by storage in ethanol) can yield trophic information that may allow investigation of temporal changes in food-web dynamics, especially where stored specimens from aquatic ecosystems subject to anthropogenic impacts are available (Vander Zanden et al 2003).…”

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confidence: 99%

“…However, C-and N-rich compounds (e.g., fatty acids and amino acids) have been detected in preservation media such as formalin and ethanol (Von Endt 1994) suggesting that preservation will alter the isotopic signatures of consumers and thereby hinder the resolution and interpretation of trophic relationships. Despite this, some isotope-based trophic studies have used preserved samples without correction for any preservation effects, particularly in instances when concurrent gut-content analyses mandated some form of sample preservation (e.g., Hall et al 2001;Mantel et al 2004). Inconsistencies in the type or concentration of preservatives, and variations in preservation duration, also reduce the robustness of isotope-based trophic comparisons among stored samples, and these effects may be taxon-specific (e.g., Vander Zanden et al 2003, and references therein; Syväranta et al 2008;Carabel et al 2009).…”

mentioning

confidence: 99%

“…The study species are representative of families that are widespread and abundant in tropical Asian streams (Dudgeon 1999) and have extensive trophic links with other co-occurring taxa (e.g., Mantel et al 2004;Li and Dudgeon 2008;Dudgeon et al 2010). Given that d 13 C and d 15 N signatures and molar C/N ratio of conspecifics-including the species involved in this studyshow a degree of inter-stream variation (Lau et al 2009a,b), we collected animals from different streams in order to incorporate this natural variation in our investigation of preservation effects.…”

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confidence: 99%

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2012

Limnology & Ocean Methods

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This study examined the effects of fluid preservatives on carbon and nitrogen stable isotopes (d 13 C and d 15 N) and C/N ratios of freshwater animals. Brotia hainanensis snails, Caridina cantonensis and Macrobrachium hainanense shrimps, and Pseudogastromyzon myersi, Liniparhomaloptera disparis, and Ctenogobius duospilus fishes were collected from seven Hong Kong streams, so as to incorporate natural variations in isotopic signals among conspecifics. Samples were preserved with 10% formalin, 70% ethanol, or formalin-ethanol solution (fixation in formalin then storage in ethanol). We compared sample molar C/N, d 13 C, and d 15 N with frozen conspecifics after 30, 60, 90, 180, and 360 d. Increases in C/N were evident in formalin-fixed shrimps and fish only, whereas DC/N attributable to ethanol and formalin-ethanol preservation was insignificant in all species. Chemical preservation generally caused d 13 C depletion in fishes and Dd 13 C significantly declined over time in formalin-ethanol-preserved L. disparis. Formalin-induced d 13 C shifts were observed in shrimps (C. cantonensis: -1.54‰; M. hainanense: -0.80‰) and snails (-0.25‰) and were relatively consistent when preservation was ≤ 60 d. The influence of formalin-ethanol on C/N and d 13 C was smaller than that of formalin for all species and more consistent than ethanol preservation. d 15 N of all species was unaffected (within ±1‰) by chemical preservation. Effects on isotopic signals were more predictable among fishes than shrimps or snails. Corrections of +1.11‰ and +1.24‰ should be applied to d 13 C of fishes preserved with formalin and formalin-ethanol (respectively) during trophic analysis. We recommend using formalin-ethanol for macroinvertebrates to limit isotopic shifts, especially those preserved for > 60 d.

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Foodweb structure in a tropical Asian forest stream

Cited by 95 publications

References 80 publications

Omnivory and resource - sharing in nutrient - deficient Rio Negro waters: stabilization of biodiversity?

Omnivory and resource - sharing in nutrient - deficient Rio Negro waters: stabilization of biodiversity?

Relationships of shredders, leaf processing and organic matter along a canopy cover gradient in tropical streams

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