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Eric Chauvet - One of the best experts on this subject based on the ideXlab platform.
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early stages of leaf decomposition are mediated by aquatic fungi in the hyporheic Zone of woodland streams
Freshwater Biology, 2010Co-Authors: Pierre Marmonier, Julien Cornut, Arnaud Elger, Didier Lambrigot, Eric ChauvetAbstract:SUMMARY 1. Leaf litter constitutes the major source of organic matter and energy in woodland stream ecosystems. A substantial part of leaf litter entering running waters may be buried in the streambed as a consequence of flooding and sediment movement. While decomposition of leaf litter in surface waters is relatively well understood, its fate when incorporated into river sediments, as well as the involvement of invertebrate and fungal decomposers in such conditions, remain poorly documented. 2. We tested experimentally the hypotheses that the small interstices of the sediment restrict the access of the largest shredders to buried organic matter without compromising that of aquatic hyphomycetes and that fungal decomposers in the hyporheic Zone, at least partly, compensate for the role of invertebrate detritivores in the Benthic Zone. 3. Alder leaves were introduced in a stream either buried in the sediment (hyporheic), buried after 2 weeks of exposure at the sediment surface (Benthic-hyporheic), or exposed at the sediment surface for the entire experiment (Benthic). Leaf decomposition was markedly faster on the streambed surface than in the two other treatments (2.1- and 2.8-fold faster than in the Benthic-hyporheic and hyporheic treatments, respectively). 4. Fungal assemblages were generally less diverse in the hyporheic habitat with a few species tending to be relatively favoured by such conditions. Both fungal biomass and sporulation rates were reduced in the hyporheic treatment, with the leaves subject to the Benthic-hyporheic treatment exhibiting an intermediate pattern. The initial 2-week stage in the Benthic habitat shaped the fungal assemblages, even for leaves later subjected to the hyporheic conditions. 5. The abundance and biomass of shredders drastically decreased with burial, except for Leuctra spp., which increased and was by far the most common leaf-associated taxon in the hyporheic Zone. Leuctra spp. was one of the rare shredder taxa displaying morphological characteristics that increased performance within the limited space of sediment interstices. 6. The carbon budgets indicated that the relative contributions of the two main decomposers, shredders and fungi, varied considerably depending on the location within the streambed. While the shredder biomass represented almost 50% of the initial carbon transformed after 80 days in the Benthic treatment, its contribution was <0.3% in the hyporheic one and 2.0% in the combined Benthic-hyporheic treatment. In contrast,
Julien Cornut - One of the best experts on this subject based on the ideXlab platform.
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early stages of leaf decomposition are mediated by aquatic fungi in the hyporheic Zone of woodland streams
Freshwater Biology, 2010Co-Authors: Pierre Marmonier, Julien Cornut, Arnaud Elger, Didier Lambrigot, Eric ChauvetAbstract:SUMMARY 1. Leaf litter constitutes the major source of organic matter and energy in woodland stream ecosystems. A substantial part of leaf litter entering running waters may be buried in the streambed as a consequence of flooding and sediment movement. While decomposition of leaf litter in surface waters is relatively well understood, its fate when incorporated into river sediments, as well as the involvement of invertebrate and fungal decomposers in such conditions, remain poorly documented. 2. We tested experimentally the hypotheses that the small interstices of the sediment restrict the access of the largest shredders to buried organic matter without compromising that of aquatic hyphomycetes and that fungal decomposers in the hyporheic Zone, at least partly, compensate for the role of invertebrate detritivores in the Benthic Zone. 3. Alder leaves were introduced in a stream either buried in the sediment (hyporheic), buried after 2 weeks of exposure at the sediment surface (Benthic-hyporheic), or exposed at the sediment surface for the entire experiment (Benthic). Leaf decomposition was markedly faster on the streambed surface than in the two other treatments (2.1- and 2.8-fold faster than in the Benthic-hyporheic and hyporheic treatments, respectively). 4. Fungal assemblages were generally less diverse in the hyporheic habitat with a few species tending to be relatively favoured by such conditions. Both fungal biomass and sporulation rates were reduced in the hyporheic treatment, with the leaves subject to the Benthic-hyporheic treatment exhibiting an intermediate pattern. The initial 2-week stage in the Benthic habitat shaped the fungal assemblages, even for leaves later subjected to the hyporheic conditions. 5. The abundance and biomass of shredders drastically decreased with burial, except for Leuctra spp., which increased and was by far the most common leaf-associated taxon in the hyporheic Zone. Leuctra spp. was one of the rare shredder taxa displaying morphological characteristics that increased performance within the limited space of sediment interstices. 6. The carbon budgets indicated that the relative contributions of the two main decomposers, shredders and fungi, varied considerably depending on the location within the streambed. While the shredder biomass represented almost 50% of the initial carbon transformed after 80 days in the Benthic treatment, its contribution was <0.3% in the hyporheic one and 2.0% in the combined Benthic-hyporheic treatment. In contrast,
Pierre Marmonier - One of the best experts on this subject based on the ideXlab platform.
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Assessing invertebrate assemblages in the subsurface Zone of stream sediments (0-15 cm deep) using a hyporheic sampler
Water Resources Research, 2014Co-Authors: Marie-josé Dole-olivier, Chafik Maazouzi, Bernard Cellot, Frank Fiers, Diana M.p. Galassi, Cécile Claret, Dominique Martin, Sylvie Merigoux, Pierre MarmonierAbstract:Quantitative comparisons between Benthic and hyporheic invertebrate communities are crucial for understanding the biological functions of the hyporheic Zone, such as storage, migrations, and exchanges of invertebrates with the surface stream. Such comparisons are still hampered by the use of different techniques adapted to each habitat (Benthic versus hyporheic). This work combines two different techniques for sampling the upper layers of bed sediments (0-15 cm): the semiquantitative ''Bou-Rouch'' pump classically used to sample the hyporheic Zone (>15 cm), and the quantitative Hess sampler commonly used to sample the Benthic Zone (ﰁ15 cm), in order to evaluate the quantitative efficiency of the pump in this 0-15 cm Zone. First, a Bou-Rouch sample (BR) was taken within the cylinder of a Hess inserted within the streambed, then a second sample (Benthic complement, BC) was collected within the Hess after removing the pump, in order to catch all invertebrates not extracted with the pump. The BR samples collected on average 14.5% of the total abundance and about 50% of the actual richness. The large range of variation indicates that the combination of the two techniques is not valid for a quantitative evaluation of Benthic communities. Contrary to expectations, the pump did not collect more interstitial and groundwater invertebrates and no differences in faunal composition between upstream and downstream riffle positions were observed. Our results do not question the use of the BR technique under standard conditions i.e., when sampling the hyporheic Zone, but underline how it is crucial to know its quantitative limits.
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Benthic and hyporheic invertebrate assemblages along a gradient of increasing streambed colmation by fine sediment
Aquatic Sciences, 2013Co-Authors: Stephane Descloux, Thibault Datry, Pierre MarmonierAbstract:Streambed colmation by fine sediment, e.g. the deposition, accumulation and storage of fines in the substrate, is a major environmental concern throughout the world. Nevertheless, the ecological effects of streambed colmation on both Benthic and hyporheic invertebrate assemblages have rarely been considered simultaneously. We studied a continuum of a naturally increasing percentage of fine sediment in three temperate rivers and hypothesized that the increasing percentage of fine sediment would decrease both Benthic and hyporheic invertebrate densities and diversities, and reduce the similarities between them. To test these hypotheses, we first compared heavily, moderately and lightly clogged reaches located in downwelling areas and sampled invertebrates in the Benthic Zone and at 3 different depths (10, 30 and 50 cm) in the hyporheic Zone. Secondly, we modified the sediment grain size distribution experimentally by increasing the percentage of fine sediment and using artificial substrates. The increasing colmation halved the hyporheic taxonomic richness and reduced Benthic and hyporheic densities to a third. Some taxa were found in both Zones, mainly in high colmation (e.g. Baetidae) or low colmation contexts (e.g. Orthocladiinae, Cyclopoida and Harpacticoida). The dissimilarity between Benthic and hyporheic fauna (only at −50 cm) was significantly higher in heavily clogged reaches than in moderately and lightly clogged ones, suggesting reduced vertical exchange of invertebrates or differential impacts between Zones. The total abundance, taxonomic richness, percentage of EPT taxa and densities of most organisms observed using the artificial substrates decreased linearly with the increasing percentage of fine sediment in the experiment. Only the Ephemeroptera Caenis spp. and Heptageniidae disappeared above 30 and 50 % of fine sediment, respectively, suggesting that the response to increasing colmation are strongly taxon-specific. High amount of fine sediments within the substrate significantly decreased habitat quality for Benthic and hyporheic invertebrates and thus limit the production of streams and their capacity to recover after disturbance. Moreover, the use of hyporheic invertebrates seems more relevant than Benthic invertebrates to assess the effect of colmation and thus could be tested in future research as indicators.
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early stages of leaf decomposition are mediated by aquatic fungi in the hyporheic Zone of woodland streams
Freshwater Biology, 2010Co-Authors: Pierre Marmonier, Julien Cornut, Arnaud Elger, Didier Lambrigot, Eric ChauvetAbstract:SUMMARY 1. Leaf litter constitutes the major source of organic matter and energy in woodland stream ecosystems. A substantial part of leaf litter entering running waters may be buried in the streambed as a consequence of flooding and sediment movement. While decomposition of leaf litter in surface waters is relatively well understood, its fate when incorporated into river sediments, as well as the involvement of invertebrate and fungal decomposers in such conditions, remain poorly documented. 2. We tested experimentally the hypotheses that the small interstices of the sediment restrict the access of the largest shredders to buried organic matter without compromising that of aquatic hyphomycetes and that fungal decomposers in the hyporheic Zone, at least partly, compensate for the role of invertebrate detritivores in the Benthic Zone. 3. Alder leaves were introduced in a stream either buried in the sediment (hyporheic), buried after 2 weeks of exposure at the sediment surface (Benthic-hyporheic), or exposed at the sediment surface for the entire experiment (Benthic). Leaf decomposition was markedly faster on the streambed surface than in the two other treatments (2.1- and 2.8-fold faster than in the Benthic-hyporheic and hyporheic treatments, respectively). 4. Fungal assemblages were generally less diverse in the hyporheic habitat with a few species tending to be relatively favoured by such conditions. Both fungal biomass and sporulation rates were reduced in the hyporheic treatment, with the leaves subject to the Benthic-hyporheic treatment exhibiting an intermediate pattern. The initial 2-week stage in the Benthic habitat shaped the fungal assemblages, even for leaves later subjected to the hyporheic conditions. 5. The abundance and biomass of shredders drastically decreased with burial, except for Leuctra spp., which increased and was by far the most common leaf-associated taxon in the hyporheic Zone. Leuctra spp. was one of the rare shredder taxa displaying morphological characteristics that increased performance within the limited space of sediment interstices. 6. The carbon budgets indicated that the relative contributions of the two main decomposers, shredders and fungi, varied considerably depending on the location within the streambed. While the shredder biomass represented almost 50% of the initial carbon transformed after 80 days in the Benthic treatment, its contribution was <0.3% in the hyporheic one and 2.0% in the combined Benthic-hyporheic treatment. In contrast,
Ute Rissebuhl - One of the best experts on this subject based on the ideXlab platform.
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contrasting habitats but comparable microbial decomposition in the Benthic and hyporheic Zone
Science of The Total Environment, 2017Co-Authors: Ute Rissebuhl, Clara Mendozalera, Helge Norf, Javier Perez, Jesus Pozo, Jeanette SchliefAbstract:Abstract Input of allochthonous leaf litter is the main carbon source for heterotrophic metabolism in low-order forested streams. A major part of this leaf litter is accumulated at Benthic retention structures or buried in the hyporheic Zone. As a result of hyporheic sediment characteristics, hyporheic physicochemistry differs from that of the Benthic Zone selecting the microbial community. The present study aimed at understanding the influence of the hydrological and physiochemical differences between the Benthic and hyporheic Zone on microbial leaf litter decomposition and on the structure and function of the associated microbial community. Leached leaves of Alnus glutinosa were exposed for 62 days in 250-μm mesh bags in the Benthic Zone and buried in the hyporheic Zone at a depth of 2–3 cm. Decomposition rates were comparable for both Zones. In contrast, respiration, bacterial abundance, ergosterol content, fungal spore production and richness of fungal morphotypes were lower associated with hyporheic than with Benthic leaves. Microbial community structure displayed Zone-dependent temporal dynamics. Thus, the microbial community carried out leaf litter decomposition independently of its structure. These results suggest that carbon processing is not necessarily impaired by environmental constraints because the community structure may compensate those constraints (i.e. functional redundancy).
Muhammad Hanif - One of the best experts on this subject based on the ideXlab platform.
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bartonian orthophragminids from the fulra limestone kutch w india and coeval units in sulaiman range pakistan a synthesis of shallow Benthic Zone sbz 17 for the indian subcontinent
Geodinamica Acta, 2018Co-Authors: Ercan Özcan, Pratul Kumar Saraswati, Ali Osman Yücel, Nowrad Ali, Muhammad HanifAbstract:Orthophragminids from the Bartonian Fulra Limestone in Kutch, India and the coeval units in Sulaiman Range in Pakistan suggest the establishment of a significant number of endemic species in the In...
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Bartonian orthophragminids from the Fulra Limestone (Kutch, W India) and coeval units in Sulaiman Range, Pakistan: a synthesis of shallow Benthic Zone (SBZ) 17 for the Indian Subcontinent
Taylor & Francis Group, 2018Co-Authors: Ercan Özcan, Pratul Kumar Saraswati, Ali Osman Yücel, Nowrad Ali, Muhammad HanifAbstract:Orthophragminids from the Bartonian Fulra Limestone in Kutch, India and the coeval units in Sulaiman Range in Pakistan suggest the establishment of a significant number of endemic species in the Indian subcontinent (Eastern Tethys). Among a total of fifteen species of Discocyclina, Orbitoclypeus and Asterocyclina, six of them appear to be confined to Indian subcontinent while seven species are common both to the peri-Mediterranean/Europe region (Western Tethys) and Indian subcontinent. Two species, Asterocyclina sireli, a four-ribbed species of possibly Indo-Pacific origin, and Orbitoclypeus haynesi that form large populations in Fulra Limestone, appear to have spread into North Africa and Turkey but not into European platforms as a response to Middle Eocene Climatic Optimum (MECO). The lack of Lutetian and Priabonian fauna in the studied sections, either due to a hiatus or unsuitable depositional environments, hampers the establishment of the actual stratigraphic ranges of the identified taxa. Our record provides us to characterize the orthophragminids in shallow Benthic Zone (SBZ) 17 for Eastern Tethys in detail by comparing the data from the above localities with those from the North Africa, Europe and Turkey, showing the change in diversity
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the inner ramp facies of the thanetian lockhart formation western salt range indus basin pakistan
Arabian Journal of Geosciences, 2014Co-Authors: Muhammad Hanif, Muhammad Imraz, Abdus Saboor, Muhammad Haneef, Shahid Iqbal, Sajjad AhmadAbstract:The Lockhart Formation from a major carbonate unit of the Paleocene Charrat Group in Upper Indus Basin, Pakistan represents a larger foraminiferal–algal build up deposited in a cyclic sequence of the carbonate ramp. The foraminiferal–algal assemblages of the Lockhart Formation are correlated here to larger foraminiferal biostratigraphic Zone, i.e. Shallow Benthic Zone (SBZ3) of the Thanetian Age. Inner ramp lagoon, shoal and fore shoal open marine are three main facies associations represented by wackstone and packstone foraminiferal–algal deposits. These facies are present in a cyclic order and displayed a retrograding carbonate ramp indicating the Thanetian transgressive deposits associated with eustatic sea level rise. The correlation of the microfacies of the Lockhart Formation (Upper Indus Basin) and facies of the Dungan Formation (Lower Indus Basin) provide detailed configuration of the depositional setting of the Indus Basin during the time interval represented by the Thanetian Zone SBZ3.