Organic Matter Flow Research Articles

Autotrophic nanoplankton dynamics is significant on the spatio-temporal variation of phytoplankton biomass size structure along a coastal trophic gradient

The biomass size structure is an intrinsic feature of phytoplankton communities that changes along the gradients of temperature, light intensity, nutrient concentrations, water column turbulence, as well as with changes in the size and the composition of the grazer community. The variations in it alter the trophic structuring in pelagic food webs leading to the quantitative changes in the flow of organic matter to the fisheries and to the deep ocean via the biological pump. The spatio-temporal dynamics of bulk and size-fractionated phytoplankton chl a biomass were studied in relation to the environmental factors at two coastal sites along the Dardanelles Strait, to test the suitability of its use as a nutrient enrichment indicator. The magnitude and the pattern of temporal change of the bulk phytoplankton biomass were very similar at two sampling sites, despite the significant variations in the spatial distributions of nutrients. Nevertheless, the spatial variation in the size fractionation of phytoplankton biomass, with significantly higher contributions of nano- and picoplankton at the nutrient-poor site reflected the nutrient gradient. Nanoplankton size fraction influenced the dynamics of the size and the size fractionation of the phytoplankton biomass, revealed by the statistically significant relations of the biomass and the relative abundance of it with each other and with the bulk phytoplankton biomass. Thus, the study altogether demonstrated; (i) the partitioning of bulk chlorophyll a biomass into size fractions may undergo changes without an accompanying change in its magnitude along the nutrient gradients, (ii) biomass size structure is a promising attribute of phytoplankton to be used as a nutrient enrichment indicator, (iii) identification and an in-depth analysis of factors influencing nanoplankton abundance are necessary for a through understanding of the spatio-temporal dynamics of the bulk and size-fractionated phytoplankton chl a biomass in the study area.

The chemical fingerprint of solubilized organic matter from eroded soils and sediments

Organic matter (OM) transfers between solid and water phases are critical components of OM cycling in surface waters as they contribute to compositional differences between dissolved OM (DOM) and particulate OM (POM). However, fractionation effects during such phase changes are not well-characterized, especially during the release of soluble OM from sediments and eroded soils. Agricultural practices alter the magnitude and timing of OM export and constitute a major source of sediment through soil erosion. This study assessed the elemental, biomolecular, and optical characteristics of DOM solubilized from sediments and soils in an agricultural watershed of northern California to trace compositional changes during OM flow from mobilized soils in streams. Relative to mineral-bound OM, solubilized DOM was nitrogen-poor (more than doubled C:N ratios) and depleted in amino acids and lignin (three- to six-fold decrease in carbon-normalized yields). Distinct fractionation patterns of individual amino acids and lignin phenols led to a more acidic pool of solubilized DOM that appeared substantially more degraded than its source POM, with decreased degradation index (DI) values and more than doubled molar contributions of non-protein amino acids and processing ratio (PR) values. Lignin composition also greatly differed in solubilized DOM compared to mineral-bound OM, with cinnamyl:vanillyl phenol ratios up to six-fold lower in solubilized lignin than in particulate lignin. Solubilized DOM generally resembled stream DOM more than its source POM and was chemically distinguishable from DOM leached from plants. Absorption coefficients and fluorescence peak intensities were strongly correlated with solubilized DOM concentrations and composition, while optical parameters established to characterize DOM origin and reactivity such as spectral slope, fluorescence index, and carbon-specific fluorescence intensities suggested unique compositional traits for solubilized DOM compared to stream DOM. This study therefore documented strong fractionation patterns during solubilization, linking eroded soil OM and stream DOM and highlighting a pathway that can account for compositional differences between DOM and POM in surface waters. A new amino acid parameter, the Solubilization Index (SI), was defined to capture the effects of solubilization processes on OM composition. SI values in solubilized DOM were up to an order of magnitude higher than in its source POM and were similar to SI values in stream DOM. Because the SI is based on empirical behaviors of individual amino acids, each tied to mechanistic interpretations, the SI is demonstrating a strong potential for mechanistic-driven research on the extent of phase changes in streamwater DOM.

WHAT HAPPENED IN THE ECOSYSTEM OF THE OKHOTSK SEA IN 2008–2018?

Critical analysis is done of the main conclusions in the article published by Yury Zuenko and co-authors in this issue of «Izvestia TINRO» journal about changes in the Okhotsk Sea biota in 2008–2018. In that paper, a continuing warming in all layers of the sea is shown quite convincingly, but weight explanations of the observed changes in marine communities and commercial stocks are not offered. Moreover, the authors ignore results of long-term studies of the Okhotsk Sea bioresources conducted from ecosystem positions. From this alternative point of view, some integrated quantitative data on dynamics of zooplankton, zoobenthos, fish, and other biota in the Okhotsk Sea are presented, as well as the schemes of organic matter and energy flows through trophic networks that show a normal functioning of the Okhotsk Sea ecosystem at the present time. On the base of these data, doubts are claimed in correctness of Zuenko’s concept of the ecosystem restructuring in direction to lower productivity and higher efficiency of its functioning.

Agricultural soil characterization using 2D electrical resistivity tomography (ERT) after direct and intermittent digestate application

This work aims to investigate the applicability of electrical resistivity tomography (ERT) as a non-destructive tool of agricultural soil characterization after digestate of fruit and vegetable (DFV) amendment application. DFV was applied at 30 t ha−1 in one application (D1), split into 2 (D2) and 6 applications (D6), and compared with initial state (IS) on field plots of 10 m2. The high-resolution 2D ERT prospecting was performed using a ABEM SAS4000 multi-electrode Lund imaging survey system with a set of 16 electrodes evenly spaced 0.1 m. The resistivity values with ERT profiles using the Wenner array range globally from 0 to 200 Ω m. All treatments proposed decreased soil resistivity to 0–30 cm depth profile. Splitting digestate shows more intensive decreasing resistivity in the top layer and less in the bottom, and moves the iso-resistivity lines lower than 30 Ω m from 7 cm depth to 12, 20, and 30 cm depth, respectively, for D6, D2, and D1. The resistivity folding at 15 to 30 cm depth was 87, 80, and 67% then 58, 42, and 37%, respectively, for D1, D2, and D6. The low resistivity values may be due to soil organic matter flow illustrated. Digestate applied once acted on the soil with heterogeneous way along the profile. Splitting it increases the thickness of foam layer homogeneously. ERT seems a promising technique for the survey of soil organic matter content monitoring, dispersion, and assessment.

Influences of fish on food web structure and function in mountain lakes

Abstract Introduction of new fish species to lakes that contain fish is known to disrupt food webs, but few studies have quantified the effects of introduced fish on flow of organic matter and mechanisms governing food web structure in historically fishless lakes. Contrasting flow of organic matter and food web structure in macroinvertebrate communities in lakes with and without fish provides an opportunity to characterise resiliency of macroinvertebrate food web function when there are changes in community composition and reductions in biomass. Organic matter flow and food web structure were characterised in six lakes with and six lakes without fish at high elevation in the southern Rocky Mountains of Colorado, U.S.A. Carbon (δ13C) and nitrogen (δ15N) were used to determine the proportionate contribution of organic matter from primary organic matter sources (periphyton, phytoplankton, terrestrial plants) to consumers including herbivores and higher trophic levels. Contributions of organic matter sources to macroinvertebrates were combined with estimates of littoral macroinvertebrate production in quantifying the contribution of each primary source to total invertebrate production. Although introduced fish altered community composition, body size, and biomass, they did not alter contributions of the organic matter sources to production of macroinvertebrates. The dominant resources contributing to macroinvertebrate production were periphyton and phytoplankton, which combined contributed to 80% of macroinvertebrate production. Despite occupying the highest trophic position (difference in δ15N relative to primary sources), fish did not alter trophic structure of littoral macroinvertebrate communities in maximum macroinvertebrate trophic position and community trophic position. Community trophic position weighted by production for macroinvertebrates was related to macroinvertebrate production per unit area but was independent of lake area. In lakes with fish, maximum macroinvertebrate trophic position was similar to that of lakes without fish because large predators (predaceous beetles and dragonflies) were replaced by small predators (tanypod chironomids). The present study indicates that macroinvertebrate food webs can exhibit resilience to introduced or invasive fish even when there are changes in community composition and biomass. This suggests that changes in structure (e.g. biomass, community composition) associated with introduced or invasive species do not necessarily equate to changes in food web function (e.g. flow of organic matter, maximum trophic position). Further, the present study suggests that although maximum trophic position has been shown to increase with lake size for lakes containing fish, the pattern is unlikely to extend to lakes without fish. The relationship between lake size and maximum trophic position for lakes containing fish may occur because fish have expandable niches associated with high motility and indeterminate growth, in contrast to macroinvertebrates.

Integrating Aquatic and Terrestrial Perspectives to Improve Insights Into Organic Matter Cycling at the Landscape Scale

Across a landscape, aquatic-terrestrial interfaces within and between ecosystems are hotspots of organic matter (OM) mineralization. These interfaces are characterized by sharp spatio-temporal changes in environmental conditions, which affect OM properties and thus control OM mineralization and other transformation processes. Consequently, the extent of OM movement at and across aquatic-terrestrial interfaces is crucial in determining OM turnover and carbon (C) cycling at the landscape scale. Here, we propose expanding current concepts in aquatic and terrestrial ecosystem sciences to comprehensively evaluate OM turnover at the landscape scale. We focus on three main concepts toward explaining OM turnover at the landscape scale: the landscape spatio-temporal context, OM turnover described by priming and ecological stoichiometry, and anthropogenic effects as a disruptor of natural OM transfer magnitudes and pathways. A conceptual framework is introduced that allows for discussing the disparities in spatial and temporal scales of OM transfer, changes in environmental conditions, ecosystem connectivity, and microbial–substrate interactions. The potential relevance of priming effects in both terrestrial and aquatic systems is addressed. For terrestrial systems, we hypothesize that the interplay between the influx of OM and its corresponding elemental composition and the elemental demand of the microbial communities – stoichiometric question – may alleviate spatial and metabolic thresholds. In comparison, substrate level OM dynamics may be substantially different in aquatic systems due to matrix effects that accentuate the role of abiotic conditions, substrate quality, and microbial community dynamics. We highlight the disproportionate impact anthropogenic activities can have on OM cycling across the landscape including reversing natural OM flows through the landscape, disrupting ecosystem connectivity, and nutrient additions that cascade across the landscape. This knowledge is crucial for a better understanding of OM cycling in a landscape context, in particular since terrestrial and aquatic compartments may respond differently to the ongoing changes in climate, land use, and other anthropogenic interferences.

Комплексна характеристика району Аргентинських островів та острова Галіндез (Морська Антарктика) як полігону для вивчення динаміки наземної рослинності

The aim of this research was generalization of base information about study area – Argentine Islands and detail characteristic of terrestrial biotopes by description and mapping of landscape elements, surface waters, and general vegetation for the chosen monitoring area of Galindez Island realized during the seasons of 2014, 2016, 2017. We also characterized animal and anthropogenic effects on the distribution of the different vegetation types. In this research a number of methods of field investigation and mapping with ArcGIS is used. Results. It was shown that most types of the available vegetation are predominantly distributed on those landscape elements, which rise above the permanent snow level, as well as get free from the snow the earliest during the summer, or they are not covered with snow in the winter. Various vegetation types can be formed here from the most sensitive to the duration of the vegetative period, e.g. communities with vascular plants, to the most tolerant to prolonged staying under snow, e.g. crustose lichens. This effect depends on the height and the sunlight availability, the duration of snow-free period on it, as well as humidity, the distance from the sea and the flow of organic matter from the sea birds. At present, in the area of the Argentine Islands in general, and on the Galindez Island in particular, the expansion of Pygoscelis papua (Spheniscidae) is observed, which has already led to the degradation of typical vegetation types in the area where these colonies had originated. The limited input of organic matter from the seabirds contributes to the development of moderately nitrophilic groups, whereas the use of these plants and lichens as the nest material leads to the distribution of vegetation in the region. The largest anthropogenic transformation occurred in the area when the station complex was built. At present, the populations of Deschampsia antarctica (Poaceae) are being formed in the area, shielded by the construction elements, which also contribute to the recolonization of certain species of scalloped lichens, but only on oldest constructions of Вritish period 1954—1996. Conclusions. It’s necessary: to continuation of monitoring of the influence of natural and anthropogenic factors on vegetation of the region; Limitation of the scientific collection of rare species, in particular Colobanthus quitensis (Caryophyllaceae); Creation of new nature protected areas with a regime of strict protection (Ia IUCN) based on the allocation of sites with the highest biodiversity valuable for monitoring in non-intervention; Additional explanatory activity on the value and vulnerability of the terrestrial ecosystems in the region.

URRENT STATE OF THE ECOSYSTEM OF LAKE UROZERO, KARELIA, ASSESSED THROUGH PRIMARY PRODUCTION AND DESTRUCTION INDICATORS

Lake Urozero has the status of a regional-level state hydrological nature monument in the Republic of Karelia. Up until the mid-2000’s, the lake have been noted for very high water transparency and the ultra-oligotrophic state of the ecosystem. In 2018, the prima-ry production and destruction characteristics of the Urozero ecosystem were studied as integral indicators of the current state and direction of its functioning. Such assessments are necessitated by the modified climatic conditions in Karelia, which affect catchments. These changes result in enlarged flow of allochtonous organic matter to water bodies. The values of photosynthesis (average 22 μg C/l per day), chlorophyll a(average 1.6 μg/l), daily assimilation number (on average 21 μg C/μg Chl), P/B factor (average 1.2 days-1) and water transparency (average 9.8 m) were measured in May, July and September. These measurements confirm that the lake ecosystem has retained its ultra-oligotrophic state. In spring and summer, when solar radiation is excessive and water transparency is high, the vertical distribution of chlorophyll ashowed a pattern unusual for Karelia, with maximum values found at the depth of one transparency. The change in the values of or-ganic matter destruction down the water column corresponds to the vertical dynamics of chlorophyll a. This vertical distribution of the values of destruction, as well as the con-sistently high transparency of the lake water, indicates that allochtonous organic mat-ter does not affect the water ecosystem. The natural ecological state of Lake Urozero in the current circumstances of climate change in the catchment area and human pres-sure is retained owing to the absence of surface inflows and nature conservation mea-sures to counteract pollution.

Litter movement pathways across terrestrial–aquatic ecosystem boundaries affect litter colonization and decomposition in streams

Abstract Streams and their riparian zones are connected by spatial flows of organic matter and constitute a model example of a meta‐ecosystem. Fluxes of leaf litter from the riparian zone to the stream are a major energy source in stream food webs. Leaf litter can enter the stream vertically, falling from the tree and into the stream, or laterally, washing into the stream after a period of exposure in the terrestrial ecosystem. The latter can contribute up to 23% to the total amount of litterfall entering streams. To determine if decomposition, microbial and invertebrate colonization of lateral litter inputs are similar to those of vertical inputs, we assessed leaf decomposition of alder, poplar and a 1:1 mixture of the two species in three scenarios across a gradient of terrestrial:aquatic exposures. Overall, decomposition was explained by a negative exponential model and decreased with the increase in the period of terrestrial exposure in all cases. Invertebrate colonization tended to decrease with the increase in the period of terrestrial exposure, but total invertebrate richness and biomass were more affected by litter type than by the exposure scenario, attaining higher values in the mixture than in the species alone. As the length of exposure in the terrestrial ecosystem increased, in‐stream decomposition rates of leaf litter decreased. Comparing leaf species treatments, alder decomposition rates were faster than poplar and the alder–poplar mixture. The richness of the aquatic hyphomycete community colonizing leaf litter after submergence decreased, and sporulation rates were strongly inhibited with an increasing terrestrial exposure period. While fungi colonizing leaf litter exposed only in the stream invested in rapid reproduction, fungi colonizing litter with prior terrestrial exposure built up more biomass. We conclude that the path taken by the litter fluxes has important effects on the functioning of the receiving ecosystem. Studies relying only on the fate of freshly abscissed leaf litter (vertical inputs) may not present a complete picture of the decomposition process in streams and may have been overestimating the overall richness and reproductive activity of the aquatic hyphomycetes colonizing leaf litter.

Alfalfa leaves as a protein source: Replacement value of alfalfa leaves for soybean-meal protein in forage-based diets fed to mature ewes

Four ruminally and duodenally cannulated mature ewes (BW65.8 4.6kg) were used in a 4x4 Latin square designed experiment to investigate the replacement value of alfalfa leaves (AL) for soybean meal (SBM) protein. Ewes received basal diets consisting of bromegrass hay, cracked corn, and one of four protein supplements. Diets were formulated to be isonitrogenous by replacing SBM with AL on a nitrogenous basis. Supplement treatments were 100% SBM; 33.3% AL and 66.7% AL and 33.3% SBM and 100% AL. Experimental periods were 14 days with 10 days of diet adaptation followed by 4 days of ruminal, duodenal, and fecal sample collection. Replacing SBM with AL decreased intake of OM and NDF (quadratic; P<.02). Intake of N increased as AL replaced SBM, which resulted in a cubic effect (P=.06). Organic matter flow and tru ruminal OM digestibility were not affected (P.18) by replacement of SBM with AL. Lower and total tract OM digestibility increased from the 33.3% AL to the 66.7% AL diet and decreased from the 66.7& AL to the 100% AL dietary treatment resulting in cubic effects (P=.01 and .03, respectively). Nitrogen flow and true ruminal N digestibility were not influenced (P.18) by supplemental protein treatment. Greater lower tract N digestibility for 33 and 67% AL resulted in a quadratic effect (P=.05, whereas total tract N digestibility was not affected (p.13) by replacing SBM with AL. No treatment differences (P.20) were detected for NDF flow or ruminal NDF digestibility. Digestibility of NDF entering the small intestine tended to respond quadratically (P=.09) with a tendency for a cubic effect (P=.08) for tor total tract NDF digestibility as a result of greater digestibility of 66.7% ALdiet. Ruminal pH increased quadratically (P=.0004), while ruminal NH3, N tended to decrease linearly (p=.10) as AL replaced SBM. Ruminal particulate and fluid passage rates were not influenced (P .21) by replacing SBM with AL. Total VFA concentrations within the rumen decreased in a quadratic (P=.05) fashion. Acetate:propionate ratio responded quadratically (P=.0001) due to higher acetate:propionate ratios for diets containing a combination of supplementary protein. Alfalfa leaves can replace soybean meal as a protein supplement; however, greater nutritional value was apparent when the two protein sources constituted the supplement.

Effect of site and provenance on the length of transfusion parenchyma of Douglas-fir needles

Douglas-fir has been the most common introduced conifer species in European plantations since 1825. The analysis of the characteristics of the introduced tree species by conducting genetic tests may predict the success of transfer of Douglas-fir seed of different provenances. The projection of the model of provenance test aims at providing information on adaptation to habitat and climate conditions in new ecosystems in Serbia. The original seed of Douglas-fir from North America was used for setting the experiment of different provenances at two sites in Serbia. The first experiment was set in a beech forest (Fagetum moesiacae montanum Jov. 1976) on district cambisol in the area of Juhor mountain in central Serbia, while the second one was set in Tanda near the town of Bor in eastern Serbia on the habitat of Hungarian and Turkey oak (Quercetum frainetto-cerris Rud. 1949) on eutric cambisol. Through the analysis of the anatomical structure of Douglas-fir needles this paper tends to determine whether there are statistically significant differences in the length of transfusion parenchyma of provenances located in different habitats. The important function of parenchyma in needles is the physiological process of water, organic and mineral matter flow. The effects of the sites where the experiments were set on the transfusion parenchyma of needles were determined by statistical analysis.

Site and extent of digestion of nitrogen compounds and organic matter in steers fed a finishing diet with dried distillers grains plus solubles supplemented with urea

Four Holstein steers (266 ± 13 kg) with ruminal and duodenal cannulae were used to evaluate the effect of inclusion of different levels of urea (0%, 0.4%, 0.8% and 1.2%) in a steam-flaked, corn-based finishing diet containing dried distillers grains plus solubles (DDGS) on the site and extent of N compounds and organic matter (OM) digestion, and on the ruminal N-NH3 and blood concentrations of urea nitrogen. Increasing the urea levels linearly decreased the OM flow to the duodenum ( P <0.04) and increased the total N and non-ammoniacal N flow to the duodenum ( P <0.01), which resulted from linear increases in the flow of microbial N and NH3-N ( P <0.01) without affecting the feed residual N flow ( P ≥0.47). Increasing the urea levels linearly increased ruminal digestion of OM and dietary N (P≤0.03), and decreased protein efficiency ( P <0.01) without affecting microbial efficiency. The urea supplementation did not affect post-ruminal digestion. Urea supplementation linearly increased ( P <0.01) total tract digestion of N compounds without affecting total tract digestion of OM. Ruminal pH averaged 6.09 ± 0.03 and was not affected ( P ≥0.97) by the inclusion of urea. Ruminal NH3-N concentration increased with urea supplementation (linear component, P<0.01). The same effect was observed for blood urea concentrations and plasma urea ( P <0.01). On the basis of the results observed here, urea can be incorporated in finishing corn-based diets that include DDGS. However, this must done carefully to avoid exceeding the RDP concentration in the diets in order to optimise ruminal fermentation and reduce the risk of high N excretion in the faeces. This is relevant when higher levels of DDGS are included in the diets (i.e. 30%). Key words : fermentation, ruminal nitrogen solubility, DDGS, plasmatic ureic nitrogen

The origin of the suspended particulate matter in the seagrass meadow of tropical waters, an evidence of the stable isotope signatures

Suspended particulate matter (SPM) has been known as an important variable in the organic matter flow of coastal ecosystem. Half of burial carbon in seagrass meadows is contributed by allochthonous sources that compose the SPM such as phytoplankton, seagrass detritus, marine snow aggregates and terrestrially derived particles. Each composition of the SPM contributes different roles and is important to be identified, for instance, the exact contribution of seagrass detritus will be useful for determination of carbon export through the detritus form in seagrass meadows. Here, the SPM of seagrass meadows is studied in Bintan Island and the Selayar Archipelago. The aim of this research is to determine the source origin of the SPM using a stable isotope signature. In order to fulfill this aim, the objectives are defined as: (1) to specify the stable isotope signature (δ13C and δ15N) of the SPM, and (2) to determine the proportional distribution of the SPM’s prospectus sources. The result shows that the possibility of the source origin of the SPM includes a seagrass fraction (Enhalus acoroides and Thalassia hemprichii), terrestrial C4 plant, macroalgae, and terrestrial C3 plant. The SPM lies between the marine- and terrigenous-end members. However, it seems that the SPM is more to be terrigenous-end and allochthonous. According to a Bayesian mixing model, the terrestrial C4 has the highest contribution of the SPM at all sites except Barugaia and Pasi Island in Selayar (i.e., the highest contribution of the SPM is from the detritus of E. acoroides). The second contribution has been contributed by either seagrass detritus (E. acoroides or Th. hemprichii) or terrestrial C3 plant. The finding of this study indicates that there is a strong influence of the terrigenous sources in the SPM of the seagrass meadows.

How do food sources drive meiofauna community structure in soft-bottom coastal food webs?

Meiofauna have a strong role in the functioning of coastal ecosystems but how their food sources affect their community structure remains unclear, likely due to the influence of abiotic parameters and the small size of these organisms. The meiofauna and their potential food sources were sampled in several intertidal habitats (i.e., mudflat, seagrass bed, sandflat) of the Marennes-Oleron Bay, France, and the Sylt-Romo Bight, Germany, to assess the relationships between habitat characteristics and meiofauna community structure. Biomass and quality (carbon/chlorophyll a ratios) of food sources were estimated. Meiofauna community structure based on density and biomass was determined, as well as nematode diversity and feeding types. Meiofauna density and biomass varied highly within habitats and within ecosystems, ranging from 1.7 × 10⁵ to 3.4 × 10⁶ ind. m⁻² and from 0.057 to 1.541 gC m⁻², respectively. Benthic microalgae and sediment organic matter are important drivers in these food webs as the density of two important trophic groups of nematodes, non-selective deposit feeders and epigrowth feeders, varied in accordance with these food sources. No clear relationship was observed between bacterial biomass and selective deposit feeders (i.e., bacterivores) probably due to the high production rate of bacteria. Complementary information about production rates of food source as well as data from trophic markers would provide complimentary information to better understand flows of organic matter in intertidal habitats, particularly for opportunistic species such as non-selective deposit feeders.

Organic-matter flow in kelp forest

Ecology and Climate![Figure][1] Laminaria ochroleuca is moving north as the climate warms. PHOTO: AGE FOTOSTOCK/ALAMY STOCK PHOTO As the global climate warms, there are shifts in the geographical distribution of organisms, which can be accompanied by changes in ecosystem functioning. Pessarrodona et al. have been investigating the ecosystem consequences of the climate-driven arrival of warm-temperate kelp forest communities to the northwestern coastlines of Europe. Cycling of organic matter in the ecosystem—through kelp growth, herbivory, and decomposition—was faster in the new communities relative to cycling in native cold-temperate kelp communities. Notably, decomposition of plant detritus occurred 6.5 times faster. The continued northward expansion of warm-temperate kelp can be expected to lead to shifts in the flow of organic matter through these ecosystems and to further changes in associated communities of consumer organisms. J. Ecol. 10.1111/1365-2745.13053 (2018). [1]: pending:yes

First report on vertical distribution of dissolved polyunsaturated aldehydes in marine coastal waters

Abstract Polyunsaturated aldehydes (PUA) are bioactive molecules released by phytoplankton cells which can modify phytoplankton trophic interactions with grazers, bacteria or coexisting phytoplankters. Their ecological significance is still a matter of debate. There have been reports of PUA producers having been investigated at the ocean surface in both coastal and open areas, but there is little information regarding natural ranges and distribution of dissolved PUA ( dPUA) once they are released. In this report, we provide novel information regarding vertical profiles of dPUA for a coastal area under two different hydrodynamical conditions (mixing and stratified waters). Results show significant concentrations of d PUA ranging from 0.061 nM to 1.87 nM during both periods. This data demonstrate a significant consistency of these compounds in coastal areas and may prove an indirect evidence of high turnover rates in seawater . The vertical distribution of d PUA showed high variability in stratification , and for the first time we describe “patches” of relatively high dPUA concentrations in the upper layer. We hypothesize that these patches of dPUA, correlated to the flow of phytoplankton-derived sinking organic matter, could be significant for increasing the turnover rates of nutrients by triggering bacterial metabolism.

Effects of dissolved organic matter, feeding, and water flow on the bioconcentration of diclofenac in crucian carp (Carassius auratus).

Diclofenac (DCF), a prevalent anti-inflammatory drug, is frequently detected in aquatic organisms. However, little is known about the environmental factors that affect the bioconcentration of DCF in aquatic environments. Here, we firstly investigated the bioconcentration of DCF by crucian carp (Carassius auratus) following aqueous exposure (3.57, 14.5, and 71.8μgL-1) for 21days. DCF can accumulate in crucian carp, and the maximum bioconcentration factors (BCFs) of 121Lkg-1 in the liver, 52.3Lkg-1 in the gills, and 46.8Lkg-1 in the muscle were always found at 3.57μgL-1 after 14days of exposure. Secondly, the influences of dissolved organic matter (DOM), feeding, and water flow on the bioconcentration of DCF were determined at the nominal concentration of 4μgL-1 for 14days. The BCFs of DCF in various fish tissues decreased by 0.5-85% with the increasing DOM concentrations. Feeding also led to lower body burden of DCF in fish tissues (6-55%) with the increasing food amount. In hydrodynamic experiment, the BCFs of DCF decreased by15-57% at most in various fish tissues. Collectively, our results demonstrated the bioconcentration of DCF in fish can be influenced by various environmental factors, which should be considered in the risk assessment of pharmaceuticals.

Сравнительный анализ состава речной взвеси северотаежной и тундровой зон Западной Сибири

The study of suspended solids in the West Siberian rivers is of great importance from the point of view of biogeochemistry, since in the rivers there are the formation and transformation of abrasion products of banks and bottom, suspended and dissolved organic matter and solid river flow, which are carried out from the land to the Kara Sea and further to the North Arctic Ocean. Studies of river suspension are necessary to understand the processes of modern sedimentation, as well as for the ecological assessment of the water area state. Mechanisms of sedimentation are largely associated with the processes of physical and biological weathering, generation, transformation and transport of suspended matter from the catchment to floodplain landscapes. In this regard, the role of studying the connection of the qualitative composition of river suspended matter with landscape parameters (level of the catchment area swappiness, nature of the soil cover, composition of soil-forming rocks, presence (absence) of permafrost, etc. is high. For example, the river of the north-taiga subzone, the catchment area of which is heavily swamped, and the river of the tundra zone with a slightly swampy watershed are represented. The influence of flood waters on the concentration of some elements in rivers with contrasting watersheds is considered. The contribution of groundwater and the effect of soil solutions on the overall migration flow are estimated.

Producción de (+)-discodermólido por la esponja Discodermia dissoluta bajo sistemas de cultivo fijo y suspendido

The macrolide (+)-discodermolide produced by the marine sponge Discodermia dissoluta shows promising antitumor, antimitotic, and immunosuppressive activity. However, the sustainable supply of any molecule requires much in situ and in vitro research to optimize and later obtain the molecule of interest. In this study, two culture systems—fixed and suspended—were evaluated at 15-m depth in two sites, Punta de Betín and Nenguange, in Santa Marta (Colombian Caribbean). Survival, growth, and production of (+)-discodermolide were recorded, with the suspended system resulting in better growth and survival, depending on the culture site. The influence of the different environmental factors on survival was also studied, and a negative correlation with temperature was observed. Salinity, solar radiation, organic matter, and water flow were not correlated. Finally, no significant differences in the production of (+)-discodermolide existed between the culture systems and study sites. Production ranged from 20 to 270 μg per gram of dry sponge.

Specific features of accumulation of humus in technozems under poplar plantations in the conditions of the Western Donbass

Specific features of accumulation of humus in technozems under poplar plantations in the conditions of the Western Donbass