Оцінка екологічного стану водосховищ гідроенергетичного призначення на р. Південний Буг за гідрогеологічними показниками

Проаналізовано особливості гідробіологічних угрупувань водосховищ гідроенергетичного призначення р.Південний Буг. Дослідження проведено за такими показниками: видовий склад, кількість, біомаса, трофічні характеристики, індекс сапробності за Пантле-Букком, за Балушкіною (для угрупувань бентосу), індекс видового різноманіття Шеннона окремо за чисельністю та біомасою, індекс Пареле, рибопродуктивність водосховищ

Soil resource supply influences faunal size–specific distributions in natural food webs

The large range of body-mass values of soil organisms provides a tool to assess the ecological organization of soil communities. The goal of this paper is to identify graphical and quantitative indicators of soil community composition and ecosystem functioning, and to illustrate their application to real soil food webs. The relationships between log-transformed mass and abundance of soil organisms in 20 Dutch meadows and heathlands were investigated. Using principles of allometry, maximal use can be made of ecological theory to build and explain food webs. The aggregate contribution of small invertebrates such as nematodes to the entire community is high under low soil phosphorus content and causes shifts in the mass–abundance relationships and in the trophic structures. We show for the first time that the average of the trophic link lengths is a reliable predictor for assessing soil fertility responses. Ordered trophic link pairs suggest a self-organizing structure of food webs according to resource availability and can predict environmental shifts in ecologically meaningful ways

Data Paper. Data Paper

<h2>File List</h2><blockquote> <a href="Dutchagroecosystems.txt">Dutchagroecosystems.txt</a><br> <a href="Traitsoilnematofauna.txt">Traitsoilnematofauna.txt</a> </blockquote><h2>Description</h2><blockquote> Soil life is complex, and huge body-size changes of organisms like soil nematodes remain enigmatic along environmental gradients and across ecosystems. Such a knowledge gap is surprising, given the importance of these invertebrates for ecosystem functioning. Moreover, differences in the biological stoichiometry between terrestrial systems are still poorly understood. Within one of the most intensive ecological soil surveys worldwide ever, containing 29552 individual records, we monitored the nematodes of 200 rural and natural areas in The Netherlands. In addition to the body length, width, and estimated mass of nematodes, this data set includes information on taxonomy, life stage, sex, feeding habit, trophic level, geographic location, sampling period, ecosystem type, soil type, and soil chemistry (pH, organic carbon, and total nitrogen and phosphorus contents). Physical, chemical, and biological information was organized over different categories regarding four soil types and three land-use types (resulting in seven combinations). Of the soil nematodes 70.8% were juveniles, 15.9% females, 5.5% males, and 7.8% Dauer larvae. Our empirical data set shows that the responses of the nematodes’ body mass to a 50-fold change in the soil molar C:P ratio were as strong as the same trait responses to a four orders-of-magnitude change in the H+ concentration in the soil. Traits like body lengths are so dependent on the life stage (here, adult vs. juvenile) that they must be taken into careful account for modeling predator–prey relationships, since nematodes are well represented in all feeding levels of the soil food webs. Traits from this novel data set can be helpful in determining habitat–response relationships, predicting effects of biological stoichiometry, and understanding the dynamics of ecosystems.<br> <br> Key words: <i>agroecosystems; biological stoichiometry; ecological stoichiometry; ecosystem types; feeding habits; nonparasitic nematodes; soil carbon; soil nitrogen; soil pH; soil phosphorus; soil types; trophic level.</i> </blockquote

What lies beneath: why knowledge of belowground biomass dynamics is crucial to effective seagrass management

Conservation of seagrasses meadows is important, because these habitats are ecologically important and under threat. Monitoring and modelling are essential tools for assessing seagrass condition and potential threats, however there are many seagrass indicators to choose from, and differentiating between natural variability and declining conditions poses a serious challenge. Tropical seagrass meadows in the Indo-Pacific, in contrast to most temperate meadows, are characterized by a multi-species composition and a year-round growth. Differences in characteristics between species growing within one meadow could induce uncertainty in the assessment of the dynamics of these meadows if variation in productivity and related biomass turnover timescales are not taken into consideration. We present data on biomass distribution, production and turnover timescales of above- and belowground tissues for three key tropical seagrass species (Thalassia hemprichii, Cymodocea rotundata and Halodule uninervis) in two mixed-species meadows in the Spermonde Archipelago, Indonesia. Seagrass leaf turnover time scales were comparable for the three studied seagrass species and varied between 25 and 30 days. Variation in leaf and rhizome turnover timescales were small (or insignificant) between the two meadows. In contrast, rhizome turnover time scales were around ten times longer than leaf turnover timescales, and large differences in rhizome turnover time scales (200-500 days) were observed between the species. The late-successional species T. hemprichii had much slower rhizome turnover compared to the two early successional species. Furthermore, since rhizome biomass has a much longer turnover time compared to leaf biomass, changes in rhizome biomass reflect effects on seagrass meadows on a much longer timescale compared to changes in leaf biomass for these tropical meadows. We conclude that belowground biomass dynamics are an important proxy to assess long-term effects of environmental stressors on seagrass ecosystems and should be included in tropical seagrass management programmes. (C) 2015 Elsevier Ltd. All rights reserved

Typology of diatom communities in the Dutch delta: Recognizing patterns of environmental drivers in nutrient rich ditches

The extensive network of waters in the lower part of the Dutch delta is loaded with nutrients and accordingly a uniform ecological classification ‘moderate’ has been derived. The present study sets out to typify the diatom communities in this apparently homogenous environment via self-organizing maps of diatom species composition. Clusters of diatom communities were characterized through the representation of ecological guilds (high and low profile, motile and planktonic) and via a RDA analysis based on either species, genus or ecological guilds together with environmental drivers. Five clusters of diatom communities were identified despite the prominence of omnipresent species. The clusters had different profiles of ecological guilds and were associated with water transparency and sediment type (peat/clay) in addition to the well-established environmental drivers related to eutrophication, but with distinct roles for nitrogen and phosphate concentration. The clusters were interpreted as functional types of community, e.g. communities with a substantial share of planktonic diatom species were found in peat ditches with turbid water. The high consistency found between diatom community classification using species, genus or guilds may allow for a simplified water quality assessment while retaining valuable ecological information. The typology, based on species, genus and ecological guilds underpins the robust use of diatoms as water quality indicators in nutrient rich lentic waters and supports steps to improve ecological conditions