Breakdown Of Organic Matter Research Articles

Effects of retention site on breakdown of organic matter in a mountain stream

Summary Organic matter inputs to streams can be retained in contrasting sites, from small leaf packs on top of cobbles to thick organic deposits trapped by wood jams. Differences in environmental conditions and in stability among sites can affect the biological communities, the quality of organic matter and its use by consumers. We measured the accumulation and composition of coarse organic matter and the breakdown of alder leaves on the surface of the streambed, inside gravel bars and in thick litter deposits trapped by log jams. We also monitored fungal sporulation rates and macroinvertebrate diversity and density in these retention sites. The amount of organic matter in these locations differed significantly among sites and ranged from 118 g m−2 in gravel to 11 562 g m−2 in jams. The biomass of shredders also differed significantly among retention sites, being highest in jams (1440 mg m−2) and lowest in gravel (86 mg m−2). Breakdown of alder leaves in fine-mesh bags did not differ among retention sites. In coarse-mesh bags, leaf breakdown rate was significantly lower in gravel bars than in surface sites or jams. Despite large differences in amount and quality of organic matter between surface sites and jams, alder leaves broke down at the same rate. Density of invertebrates in bags and fungal sporulation rates tended to be highest in surface sites and lowest in gravel bars. The contribution of microbes to breakdown was 67% in gravel, 52% in surface and only 28% in jams. Overall, the differences among sites in leaf breakdown were correlated with invertebrate density. Our results showed large differences in the amount and quality of organic matter accumulated, in biological communities and in the use of organic matter among retention sites of a single stream reach. This spatial variability should be taken into account in studies of ecosystem functioning related to organic matter.

Temporal and Spatial Patterns of Macroinvertebrates Associated with Small and Medium-Sized Free-Floating Plants

Macrophytes play an important role in structuring communities in aquatic ecosystems due to their influence on ecological processes and attributes of biological aquatic assemblages. Freshwater macroinvertebrates comprise a functionally and taxonomically diverse group in shallow lakes, which serve as food for fish, amphibians, and water birds, and are involved in the breakdown of organic matter and nutrients. Here, we investigated macroinvertebrate assemblages associated with small and medium-sized free-floating plants (FFP) by describing their structure, analyzing functional aspects (considering functional feeding groups and habits), and determining how much of the variation in fauna composition is explained by environmental factors, mainly FFP. Differences in structure, functional feeding groups and habits of macroinvertebrate assemblages were associated with different compositions and percentages of cover of FFP. Gradients of richness and diversity of macroinvertebrates were positively related to the complexity of FFP mats, which was associated with the structure of roots and leaves.

Organic matter breakdown as a measure of stream health in New Zealand streams affected by acid mine drainage

Functional indicators of stream health have the potential to provide insights into stream condition that cannot be gained by traditional structural indices. We examined breakdown of leaves, wood, and cotton cloth strips at 18 sites along a gradient of effects of drainage from coal mines in New Zealand to determine the usefulness of these methods as functional indicators of stream health. The pH varied from 2.7 to neutral across the streams, and the more acidic streams typically had higher concentrations of aluminum, iron, zinc, and other metal ions. Precipitates of metal (mainly iron) hydroxides were present in most streams affected by mine drainage, especially in those with a pH of 4–5. Breakdown rates of all organic matter types were highest in several reference streams with neutral pH and lowest in sites with high rates of metal hydroxide deposition. Breakdown was relatively fast in the most acidic streams (pH<3), in some cases as fast as at reference sites; these sites also had elevated nutrient concentrations. Shredding invertebrates were absent in litterbags from acidic streams and common at only 2 reference sites; their presence contributed to fast breakdown of leaves in the field and in lab microcosms. Microbial respiration was closely related to breakdown rates of leaves and wood; it was high at neutral and highly acidic streams, but lower at sites with pH 4–5, where metal hydroxides were precipitating onto solid surfaces. In these metal hydroxide-stressed streams, leaf and wood breakdown was slower, and associated biota, including microbes, were more affected than by water chemistry stressors (pH, dissolved metals) associated with mine drainage. Litter breakdown and microbial respiration provide insight into the functioning of streams, yielding different responses than traditional structural measures based on macroinvertebrates, which did not accurately distinguish impacts from acid mine drainage.

The use of wooden sticks to assess stream ecosystem functioning: Comparison with leaf breakdown rates

Breakdown of organic matter is a key process in streams and rivers, and thus, it has potential to assess functional impairment of river ecosystems. Because the litter-bag method commonly used to measure leaf breakdown is time consuming and expensive, several authors proposed to measure breakdown of wooden sticks instead. Nevertheless, currently there is little information on the performance of wooden sticks versus that of leaves. We compared the breakdown of tongue depressors made of untreated poplar wood, to that of six common leaf species in two large streams in the Basque Country (northern Spain), one polluted and the other unpolluted. Breakdown rates ranged from 0.0011 to 0.0120day−1, and were significantly lower in the polluted stream. Wooden sticks performed very similarly to leaves, but were less affected by flood-induced physical abrasion. The ranking of the materials according to their breakdown rate was consistent, irrespective of the stream. The experiments with leaves were 10 times more costly for breakdown rate, 4 times if we include the rest of the variables measured. Therefore wooden sticks offer a promising tool to assess river ecosystem functioning, although more research is necessary to define the thresholds for ecosystem functional impairment.

Effects of road deicer (NaCl) and amphibian grazers on detritus processing in pond mesocosms

Road deicers have been identified as potential stressors in aquatic habitats throughout the United States, but we know little regarding associated impacts to ecosystem function. A critical component of ecosystem function that has not previously been evaluated with respect to freshwater salinization is the impact on organic matter breakdown. The purpose of this study was to evaluate cumulative effects of road deicers and tadpole grazers on leaf litter breakdown rate (g d(-1) ) and microbial respiration (mg O(2) g leaf(-1) h(-1) ). To test this interaction, in May 2008 the authors added dry leaf litter (Quercus spp.) to forty 600-L pond mesocosms and inoculated each with algae and zooplankton. In a full-factorial design, they manipulated a realistic level of road salt (ambient or elevated at 645 mg L(-1) Cl(-) ) and tadpole (Hyla versicolor) presence or absence. The elevated chloride treatment reduced microbial respiration by 24% in the presence of tadpoles. The breakdown of leaf litter by tadpoles occurred 9.7% faster under ambient chloride conditions relative to the elevated chloride treatment. Results of the present study suggest that the microbial community is directly impacted by road deicers and heavy tadpole grazing under ambient conditions limits microbial capacity to process detritus. Road salts and tadpoles interact to limit microbial respiration, but to a lesser extent leaf mass loss rate, thereby potentially restricting energy flow from detrital sources in pond ecosystems.

Assessing the effects of multiple stressors on the functioning of Mediterranean rivers using poplar wood breakdown

Mediterranean rivers in the Iberian Peninsula are being increasingly affected by human activities, which threaten their ecological status. A clear picture of how do these multiple stressors affect river ecosystem functioning is still lacking. We addressed this question by measuring a key ecosystem process, namely breakdown of organic matter, at 66 sites distributed across Mediterranean Spain. We performed breakdown experiments by measuring the mass lost by wood sticks for 54 to 106days. Additionally, we gathered data on physico-chemical, biological and geomorphological characteristics of study sites.Study sites spanned a broad range of environmental characteristics and breakdown rates varied fiftyfold across sites. No clear geographic patterns were found between or within basins. 90th quantile regressions performed to link breakdown rates with environmental characteristics included the following 7 variables in the model, in decreasing order of importance: altitude, water content in phosphorus, catchment area, toxicity, invertebrate-based biotic index, riparian buffer width, and diatom-based quality index. Breakdown rate was systematically low in high-altitude rivers with few human impacts, but showed a high variability in areas affected by human activity. This increase in variability is the result of the influence of multiple stressors acting simultaneously, as some of these can promote whereas others slow down the breakdown of organic matter. Therefore, stick breakdown gives information on the intensity of a key ecosystem process, which would otherwise be very difficult to predict based on environmental variables.

Paleoenvironmental and taphonomic controls on the occurrence of Paleoproterozoic microbial communities in the 1.88 Ga Ferriman Group, Labrador Trough, Canada

Chert and iron formation from the Ferriman Group (ca. 1.88Ga), Labrador Trough, Canada, contain an exceptional assemblage of fossil bacteria and biofilms preserved within a well-defined stratigraphic framework. Lithofacies associations suggest that microbes were restricted to suboxic, shallow-water environments through three sea-level cycles. Microfossils are preserved as chert or sedimentary apatite (francolite) in hematite-rich, peritidal facies. Nearshore evaporation and Fe-redox pumping of silica drove rapid penecontemporaneous silicification of microbial mats. In some communities, breakdown of organic matter and Fe-redox pumping of pore water phosphate caused their syndepositional phosphatization. Preservation of bacteria was precluded in deeper settings because these processes could not operate at an anoxic seafloor.Filamentous forms dominate microbial morphologies. Secondary electron imaging of freshly broken surfaces shows filaments that are similar in size and shape to modern bacteria; filaments vary from 0.5 and 1μm wide and reach tens of μm in length. They commonly envelop chert and iron oxide grains, which stabilized the seafloor and contributed to firmground development. The filamentous morphology, similar mat-forming behavior, and suboxic paleoenvironments where these fossils lived are consistent to those of modern Fe-oxidizing bacteria and some cyanobacteria. Associated organic matter with low δ13C values is also present. Most values vary between ca. −38 and −20‰, which is consistent with isotopic fractionation by such bacteria. Unlike modern settings, however, their distribution was restricted to shallow marine and peritidal environments where photosynthetically produced oxygen oases likely impinged on the seafloor. Although Fe-oxidizing bacteria were possibly important in forming some iron formation facies in the Ferriman Group, physiochemical precipitation of Fe-(oxyhydr)oxides caused by photosynthetic oxygen was also probably widespread in the photic zone across the shelf. This study demonstrates that a combined microanalytical, sedimentologic, and stratigraphic analysis of fossil bacteria not only yields a more detailed picture of the Precambrian biosphere, but also highlights the importance of taphonomy in the search for early life.

Stable isotope probing of bacterial community structure and gene expression in the rhizosphere of Arabidopsis thaliana

The rhizosphere is an active compartment where plant and microorganisms establish a molecular dialogue. In this study, we analysed the impact of Arabidopsis thaliana on bacterial community structure and the expression of certain beneficial genes using DNA- and mRNA-SIP in the rhizosphere of plantlets grown under (13)CO(2) for 13, 21 and 27 days. DNA- and rRNA-SIP revealed changes in bacterial communities inhabiting the rhizosphere soil that were probably related to modification of root exudates, while root-colonizing populations were maintained over time suggesting their metabolic versatility and adaptation. The impact of the plant via root exudates on the expression of the noncoding RNAs rsmZ, acdS gene encoding 1-aminocyclopropane-1-carboxylate deaminase and nosZ gene encoding nitrous oxide reductase, in the root-adhering soil and on the roots of A. thaliana was determined using mRNA-SIP. Results showed that these genes were present and expressed by bacteria inhabiting roots and by those that derive nutrients from the breakdown of organic matter in soils or from root exudates. The expression of rsmZ under natural conditions indicates the importance of noncoding RNAs in bacterial adaptation to their ecological niches.

Microbial control over carbon cycling in soil.

A major thrust of terrestrial microbial ecology is focused on understanding when and how the composition of the microbial community affects the functioning of biogeochemical processes at the ecosystem scale (meters-to-kilometers and days-to-years). While research has demonstrated these linkages for physiologically and phylogenetically “narrow” processes such as trace gas emissions and nitrification, there is less conclusive evidence that microbial community composition influences the “broad” processes of decomposition and organic matter (OM) turnover in soil. In this paper, we consider how soil microbial community structure influences C cycling. We consider the phylogenetic level at which microbes form meaningful guilds, based on overall life history strategies, and suggest that these are associated with deep evolutionary divergences, while much of the species-level diversity probably reflects functional redundancy. We then consider under what conditions it is possible for differences among microbes to affect process dynamics, and argue that while microbial community structure may be important in the rate of OM breakdown in the rhizosphere and in detritus, it is likely not important in the mineral soil. In mineral soil, physical access to occluded or sorbed substrates is the rate-limiting process. Microbial community influences on OM turnover in mineral soils are based on how organisms allocate the C they take up – not only do the fates of the molecules differ, but they can affect the soil system differently as well. For example, extracellular enzymes and extracellular polysaccharides can be key controls on soil structure and function. How microbes allocate C may also be particularly important for understanding the long-term fate of C in soil – is it sequestered or not?

Relating carrion breakdown rates to ambient resource level and community structure in four cave stream ecosystems

Detrital inputs into ecosystems vary in quantity and quality (e.g., plant litter vs carrion). Variability in detrital quantity and quality potentially affects consumer biomass and rates of organic matter (OM) breakdown. We used cave streams to test 2 linked hypotheses regarding the influence of total detrital inputs on consumer biomass and the breakdown of high-quality carrion detritus. First, we hypothesized that cave systems with higher total OM availability would support a higher biomass of consumers. Second, we predicted that higher consumer biomass would cause faster carrion breakdown rates. To test these hypotheses, we quantified macroinvertebrate biomass and breakdown rates (k, d−1) of carrion (mouse carcasses, Mus musculus) in 4 cave streams in northeastern Alabama and southeastern Tennessee (USA) that varied in total OM storage. We estimated carrion breakdown rates in coarse- and fine-mesh packs (10-mm and 500-µm mesh size) to isolate the influence of scavenging by crayfish. Macroinvertebrate biomass (excluding crayfish) in carrion packs was positively correlated with OM storage, but neither macroinvertebrate biomass (excluding crayfish) nor OM storage were strong predictors of carrion breakdown rates. Crayfish biomass was not correlated with total OM storage but was positively correlated with coarse-mesh breakdown rates. Our study illustrates the influence of community structure and consumer biomass on detrital breakdown rates in cave ecosystems. However, determining how detrital inputs structure cave communities will require further study.

Changes of Physico–Chemical Properties of Pig Slurry During Storage

This study was aimed to determine changes of the characteristics of raw pig slurry as liquid organic fertilizer at various storage times. A completely randomized design was used in this research. The treatments were storage times, i.e.: 0, 15, 30, 45, and 60 days. Variables observed were loss of the slurry, degree of acidity (pH), electrical conductivity (EC), total solid (TS), volatile solid (VS), total chemical oxygen demand (tCOD), soluble chemical oxygen demand (sCOD), total nitrogen (TN), ammonia-nitrogen (NH3-N), nitrate-nitrogen (NO3-N), total phosphate (TP), and dissolve reactive phosphate (DRP). The results showed that storage time significantly affected all the observed variables, except the concentration of NO3-N and total phosphate content. The pH, TS, VS, DRP, and losses of slurry lost during storage times increased, while EC, TN, NH3-N, tCOD, and sCOD decreased. Physico-chemical properties of slurry during storage times changed, as a result of organic matter breakdown.

수송용 대체연료로서 바이오메탄의 잠재적 타당성 연구

Biogas production and utilization are an emerging alternative energy technology. Biogas is produced from the biological breakdown of organic matter through anaerobic digestion. Biogas can be utilized for various energy sectors such as space heating, electricity generation and vehicle fuel. Especially, to be utilized as vehicle fuel, raw biogas needs to be upgraded that is mainly the removal of carbon dioxide to increase the methane content up to more than 95 ~ 97 vol% in some cases, similar to the composition of fossil-based natural gas. Usage of Biogas as a fuel of vehicles have an effect of reducing <TEX>$CO_2$</TEX> emission compared to fossil fuels. Biomethane which is produced by upgrading of biogas is regarded as a good alternative energy and usage of clean energy is encouraged to deal with air pollution and waste management as well as production of clean energy. Recently, biogas projects for vehicle fuel are newly being launched and Korea government have also announced a plan for investment to develop biogas as a transport fuel. In this study, it is aimed to examine the potential feasibility of biomethane as a transport fuel. As a results, the status of biomethane, quality standard, quality characteristics, and upgrading technology of biogas were investigated to evaluate of biogas as a vehicle fuel of transportation.

Assimilation of upwelled nitrate by small eukaryotes in the Sargasso Sea

Phytoplankton growth is potentially limited by the scarcity of biologically available forms of nitrogen such as nitrate and ammonium. In the subtropical ocean gyres, water column stratification impedes the upward flux of nitrate to surface waters. Phytoplankton in these waters are assumed to rely largely on ammonium and other forms of nitrogen recycled during the breakdown of organic matter. Here, we use flow cytometry to separate prokaryotic and eukaryotic phytoplankton collected from Sargasso Sea surface waters in the summers of 2008 and 2009, and to analyse their respective nitrogen isotope ratios. We show that prokaryotes have a uniformly low ratio of 15 N to 14 N, 15 N, consistent with their reliance on recycled nitrogen. In contrast, small eukaryotic phytoplankton, less than 30m in size, have a higher and more variable 15 N, with a mean value similar to that of nitrate in underlying Subtropical Mode Water. For the summertime Sargasso Sea, we estimate that small eukaryotes obtain more than half of their nitrogen from upwelled nitrate. In addition, our data support the view that sinking material derives largely from eukaryotic, not prokaryotic, phytoplankton biomass.

Effects of pesticide toxicity, salinity and other environmental variables on selected ecosystem functions in streams and the relevance for ecosystem services

Effects of anthropogenic and environmental stressors on freshwater communities can propagate to ecosystem functions and may in turn impede ecosystem services. We investigated potential shifts in ecosystem functions that provide energy for freshwater ecosystems due to pesticides and salinity in 24 sites in streams of southeast Australia. First, effects on allochthonous organic matter (AOM) breakdown using three different substrates (leaves, cotton strips, wood sticks) in coarse and fine bags were investigated. Second, we examined effects on stream metabolism that delivers information on the ecosystem functions of gross primary production and ecosystem respiration. We found up to a fourfold reduction in AOM breakdown due to exposure to pesticides and salinity, where both stressors contributed approximately equally to the reduction. The effect was additive as, no interaction or correlation between the two stressors was found. Leaf breakdown responded strongly and exclusively to exposure to pesticides and salinity, whereas cotton strip breakdown was less sensitive and responded also to other stressors such as nutrients. No functional redundancy for the effects of pesticides and salinity on leaf breakdown was observed. For wood stick breakdown, no relationship to environmental gradients was found, however, the sample size was lower. We did not detect effects of pesticides or salinity on gross primary production or ecosystem respiration. A reduction in AOM breakdown by pesticides and salinity may impair the ecosystem services of food provision and possibly water purification. Hence, future studies should examine the spatial extent of these effects.

Experimental wood addition in streams: effects on organic matter storage and breakdown

Summary 1. Channel complexity affects the physical structure, biotic communities and functioning of stream ecosystems. Large wood (LW) is a key element in the creation and maintenance of physically complex stream channels in forested areas. 2. In an attempt to enhance stream habitat quality and ecosystem functioning and to reduce inputs of organic matter to a downstream reservoir, LW was experimentally introduced into four mountain streams in the Basque Country (northern Spain), ranging in channel width from 3 to 13 m. Following a before–after/control–impact (BACI) design, streams were monitored during 1 year prior to wood addition and during 2 years after addition in one control and one experimental reach per stream. 3. Areal cover of benthic organic matter in the entire channel was measured from regular transects and the mass of stored organic matter from random Surber samples. Breakdown of organic matter was assessed in litter bag experiments performed with black alder leaves. When 50% of the initial mass in the bags remained, invertebrates associated with leaf bags were collected. 4. Wood placement produced a 2- to 70-fold increase in the storage of organic matter, especially in thick deposits upstream from wood jams, with values in excess of 2 kg AFDM per m2 in the small streams. The accumulation of organic matter produced by wood introduction decreased with increasing stream size. 5. Despite the large increase in the availability of organic matter, litter breakdown rates were unaffected by the experimental reaches, suggesting large increases in the total amount of organic matter consumed at the reach scale. 6. Numbers of invertebrates and shredders per gram of leaf litter did not respond to wood addition. Average body mass of invertebrates associated with leaf litter showed a non-significant decreasing trend, which might reflect increased recruitment. 7. Although the effects of wood addition can depend on wood stability and stream size, adding LW to restore channel complexity can improve environmental conditions for invertebrate communities and affect stream ecosystem functioning, enhancing the efficiency to use organic matter inputs on a reach scale.

Evaluation of Nitrate-Nitrogen Leaching From Lysimeter-Grown Bearing Apple Trees

A 2-year investigation was conducted on eight replicate plots located 30 miles east of Lake Michigan on sand to sandy-clay-loam soil, using 1.8-m-deep lysimeters (4.8 m of volume), consisting of an undisturbed monolith excavated from the soil and containing a bearing (2- to 3-year-old) apple tree each. The aims of this research were to study the leaching rate and migration time of nitrate-N (NO3-N) through the soil profile and to assess the suitability of soil suction tube (SST) water samples to predict the NO3-N leaching rate. The NO3-N concentration in the water collected by the lysimeters ranged from less than 10 mg L (in late summer) to more than 40 mg L (in winter). We calculated that NO3-N lost via leaching in a year amounts up to 141 kg ha, with the most potential for groundwater pollution occurring during the cold and wet season. The application of labeled N ammonium nitrate as fertilizer increased the concentration of NO3-N in the solution collected by SST. Labeled N was found at the bottom of lysimeters 3 months after its application, leaching through the soil profile at a speed of 2 cm day, so that the NO3-N concentration of SST was correlated significantly with NO3-N concentration of lysimeters only when the time of movement was considered. The application of fertilizer did not increase the amount of NO3-N collected by lysimeters, meaning that the NO3-N leaching rate is mostly the result of the breakdown of soil organic matter.

Amoniako ir metano dujų, išsiskiriančių kompostuojant nuotekų dumblą, tyrimai

Nuotekų dumblas, jo apdorojimas ir saugojimas yra susijęs su klimato kaita. Yrant organinėms medžiagoms išsiskiria ne tik nemalonaus kvapo dujų, bet ir šiltnamio efektą sukeliančių dujų (CO2, CH4, NOx). Biodegradacijos procesai vyksta ir natūraliai gamtoje ir dirbtinai – kompostuojant. Sudarant optimalias kompostavimo sąlygas (C:N, aeravimas, pH ir drėgmė) bei naudojant priedus (ceolitas, durpės ir kt.) galima mažinti dujinių teršalų emisijas į aplinką. Straipsnyje nagrinėjami kompostuojant nuotekų dumblą gautų eksperimentų rezultatai, tiriant CH4 ir NH3. Eksperimentui naudotas Vilniaus miesto komunalinių nuotekų valymo įrenginių perteklinis nuotekų dumblas, nusausintas centrifugomis. Kaip papildomos medžiagos naudotos ceolitas ir durpės. Kompostuota kompostavimo aikštelę imituojančiuose „įrenginiuose“.

No UV enhancement of litter decomposition observed on dry samples under controlled laboratory conditions

Abstract In field studies, various workers have observed a stimulation of organic matter breakdown by visible light and UV radiation. We aimed to confirm the involvement of UV radiation under controlled laboratory conditions and quantify the magnitude of any stimulation. Grass and pine foliage samples were oven-dried and continuously exposed to UV radiation at room temperature for up to 60 days. A range of UV flux densities was established using shading to different levels. After UV exposure under air-dry conditions, samples were rewetted and incubated in the dark with microbial inoculums to investigate whether UV exposure had rendered samples more susceptible to subsequent microbial decomposition. However, we found no weight loss associated with different UV flux densities. The same finding held true for grass and pine litter samples. Similarly, microbial decomposition of either grass or pine litter was not enhanced by prior UV exposure. These findings suggest that UV-induced photooxidation of dry materials cannot be responsible for the observed apparent enhancement of weight loss of litter samples under UV exposure in the field.

Magnetic properties of the youngest sapropel S1 in the Ionian and Adriatic Sea: inference for the timing and mechanism of sapropel formation

The youngest sapropel S1 has been investigated by a multiproxy study on a core (ET99-M11) collected in the western Ionian Sea at a water depth of 2800 m, which is considered to represent anoxic conditions in the eastern Mediterranean at the time of sapropel formation. Selected geochemical parameters (TOC, Ba/Al, MnO) as well as micropaleontological analysis (planktic foraminifera), rock magnetic data, and 14 C dating indicate that anoxic conditions prevailed between 10.4 and 5.7 ka BP. The comparison among the different proxies indicates that rock magnetic parameters can be unambiguously used to precisely identify sapropel layers, even if no iron sulphide phases have been precipitated as a bi-product of diagenetic breakdown of organic matter. By using the magnetic parameters as indicators of paleoredox conditions we compare the results with cores collected in the central and southern Adriatic Sea at different water depths. A shorter duration (9.6/9-7/6.8 ka BP) of the sapropel S1 was observed in the deepest southern part of the basin and in the Meso Adriatic Depression whereas suboxic conditions continued in cores collected at very shallow water depth of 56 m along the western margin of the basin. The formation of the Adriatic Deep Water driven by decreasing solar radiation output is considered responsible for the interruption and end of sapropel formation.

Amplified ribosomal DNA restriction analysis as a routine tool to assess toxicant driven changes in hindgut bacterial populations of Porcellio dilatatus (Crustacea: Isopoda)

Changes in saprophytic organism's gut microbial communities may present a threat to organic matter breakdown which can ultimately lead to soil function impairment. In this study, Amplified Ribosomal DNA Restriction Analysis (ARDRA) was evaluated as a potential simple molecular tool to assess shifts in bacterial community structure in hindgut populations of Porcellio dilatatus exposed to contaminated food. This prospective tool can also be used for a variety of purposes and samples prior to the use of more specific and sophisticated methods.