Porous Media and Aquifer Systems

Zilliox, L.

doi:10.1016/b978-0-08-050762-0.50010-3

Cited by 4 publications

(5 citation statements)

References 3 publications

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“…(1997) suggest that the influence of organic matter depends on, and is sometimes outweighed by, other mechanisms and processes determining the number and composition of co‐occurring species in a local environment. For instance, the variability of pore sizes in the three dimensions of the hyporheic zone results in complex fluid distribution patterns (Zilliox, 1994). These spatial complexity and heterogeneity are reflected in the dispersion patterns of invertebrates.…”

Section: Discussionmentioning

confidence: 99%

Early stages of leaf decomposition are mediated by aquatic fungi in the hyporheic zone of woodland streams

et al. 2010

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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, Correspondence: Julien Cornut, Laboratoire d'écologie fonctionnelle, 2541 mycelial and conidial production in the permanently hyporheic environment accounted for 12% of leaf mass loss, i.e. 2-3 times more than in the two other conditions. These results suggest that the role of fungi is particularly important in the hyporheic zone. 7. Our findings indicate that burial within the substratum reduces the litter breakdown rate by limiting the access of both invertebrate and fungal decomposers to leaves. As a consequence, the hyporheic zone may be an imp...

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Section: Discussionmentioning

confidence: 99%

Early stages of leaf decomposition are mediated by aquatic fungi in the hyporheic zone of woodland streams

et al. 2010

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“…Depending on the structure and porosity of the sedimentary matrix (e.g., variability of pore sizes in the three dimensions of the hyporheic zone; Zilliox, 1994), such water movements result in complex fluid distribution patterns (Williams and Hogg, 1988;Findlay, 1995). Stream water enters the hyporheic habitat through downwelling zones (Whitman and Clark, 1984;White et al, 1987) and returns to the streambed surface (i.e., benthic habitat) through upwelling zones or can penetrate deep into the ground water of alluvial aquifers (Harvey and Bencala, 1993;Valett et al, 1996;Wroblicky et al, 1998;Crenshaw et al, 2002).…”

Section: Groundwater and Hyporheic Habitatmentioning

confidence: 99%

Beyond the water column: aquatic hyphomycetes outside their preferred habitat

et al. 2016

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b s t r a c tAquatic hyphomycetes have adapted to running waters by their uncommon conidial shape, which facilitates dispersal as well as adherence to plant substrata. However, they have been early and regularly reported to occur in a variety of environments other than their preferred habitat (e.g., in lentic freshwaters, brackish and marine environments, in terrestrial niches such as stream banks, dew, canopy waters and tree holes). In addition, several aquatic hyphomycetes have adapted to a mutualistic lifestyle which may involve plant defence, as endophytes in leaves, gymnosperm needles, orchids and terrestrial roots.There are several lines of evidence suggesting that aquatic hyphomycetes survive under terrestrial conditions due to their sexual states. Although exhibiting higher diversity in pristine streams, aquatic hyphomycetes can survive environmental stress, e.g., pollution or river intermittency. They also inhabit ground and hyporheic waters, where they appear to be subjected to both physical and physiological selection. Appropriate methods including molecular ones should provide a more comprehensive view of the occurrence and ecological roles of aquatic hyphomycetes outside their preferred habitat.

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“…Geology accounts strongly for differences in biota between aquifers (Hahn 2006, Stein et al 2012, Johns et al 2015, but it also is important within aquifers because the particle size and composition of the aquifer matrix determine the size of interstitial spaces. Interstitial spaces provide habitat for groundwater invertebrates (collectively termed stygofauna) and microbes (Zilliox 1994, Coineau 2000, and influence the hydraulic conductivity and flow of water, which is the means of delivery of C and O 2 throughout the ecosystem. Water quality, including C, O 2 , and other chemical constituents, also is a key factor determining the suitability of the subterranean habitat and, hence, the distribution of biota.…”

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confidence: 99%

Habitat, water quality, seasonality, or site? Identifying environmental correlates of the distribution of groundwater biota

Korbel

Hose

2015

Freshwater Science

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The distribution of biota in aquatic ecosystems, including aquifers, is collectively influenced by habitat structure, water quality, seasonality, and local variations in environmental conditions. However, little is known about the nature and relative influences of such factors in groundwater ecosystems. Our aims were to identify the key environmental variables influencing the distribution of biota within the Gwydir River alluvial aquifer in northwestern New South Wales, Australia, and to consider the relative importance of environmental variables, in terms of habitat structure, water quality, seasonality, and site attributes, to both microbial and invertebrate (stygofauna) assemblages. Stygofauna distribution was primarily influenced by habitat variables (predominantly sediment structure) followed by site variables (abundance of trees), with water quality and seasonality having relatively little influence. These results indicate that it is the aquifer conditions relating to habitat structure, water flow, and the supply of organic matter that are most important for determining stygofauna distribution. Microbial assemblage structure was not strongly correlated with habitat variables, possibly because habitat restraints do not exist because of their smaller size. Instead, seasonality and water-quality variables had the greatest influence on microbial assemblages. Microbes might respond to seasonal (particularly rainfall induced) changes in water quality more quickly than do stygofauna, which may explain the relatively greater importance of seasonality and water quality to microbial assemblages. Given that stygofauna are most influenced by habitat and site variables, and microbial assemblages are most influenced by seasonality and water quality, disturbance to any of these factors may threaten the stability and integrity of the groundwater ecosystem.

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Porous Media and Aquifer Systems

Cited by 4 publications

References 3 publications

Early stages of leaf decomposition are mediated by aquatic fungi in the hyporheic zone of woodland streams

Early stages of leaf decomposition are mediated by aquatic fungi in the hyporheic zone of woodland streams

Beyond the water column: aquatic hyphomycetes outside their preferred habitat

Habitat, water quality, seasonality, or site? Identifying environmental correlates of the distribution of groundwater biota

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