Biodiversity restoration of formerly extracted raised bogs: vegetation succession and recovery of other trophic groups

Bioindicators assess the mangroves ecological state according to the types of pressures but they differ with the ecosystem’s specificities. We investigated benthic meiofauna diversity and structure within the low human-impacted mangroves in French Guiana (South America) in response to sediment variables with various distances to the main city. Contaminant’s concentrations differed among the stations, but they remained below toxicity guidelines. Meiofauna structure (Foraminifera, Kinorhyncha, Nematoda) however varied accordingly. Nematode’s identification brought details on the sediment’s quality. The opportunistic genus Paraethmolaimus (Jensen, 1994) strongly correlated to the higher concentrations of Hg, Pb. Anoxic sediments were marked by organic enrichment in pesticides, PCB, and mangrove litter products and dominance of two tolerant genus, Terschellingia (de Man, 1888) and Spirinia (Gerlach, 1963). In each of these two stations, we found many Desmodora individuals (de Man, 1889) with the presence of epibionts highlighting the nematodes decreased fitness and defenses. Oxic sediments without contaminants were distinguished by the sensitive genera Pseudocella (Filipjev, 1927) and a higher diversity of trophic groups. Our results suggested a nematodes sensitivity to low contaminants concentrations. Further investigations at different spatio-temporal scales and levels of deterioration, would be necessary to use of this group as bioindicator of the mangroves’ ecological status.

Highly humic lakes are typical for the boreal zone. These unique ecosystems are characterised as relatively undisturbed habitats with brown water, high acidity, low nutrient content and lack of macrophytes. Current lake assessment methods are not appropriate for ecological assessment of highly humic lakes because of their unique properties and differing human pressures acting on these ecosystems. This study proposes a new approach suitable for the ecological status assessment of highly humic lakes impacted by hydrological modifications. Altogether, 52 macroinvertebrate samples from 15 raised bog lakes were used to develop the method. The studied lakes are located in the raised bogs at the central and eastern parts of Latvia. Altered water level was found as the main threat to the humic lake habitats since no other pressures were established. A multimetric index based on macroinvertebrate abundance, littoral and profundal preferences, Coleoptera taxa richness and the Biological Monitoring Working Party (BMWP) Score is suggested as the most suitable tool to assess the ecological quality of the highly humic lakes.

Abstract The effects of various concentrations of herbicide Euro-Lightning Plus on the state of microbiota in the root zone of sunflower have been studied. Soil of plant rhizosphere and interrow soil after treatment with the herbicide at the doses of 1.2 and 2.5 l/ha were taken for the analysis at the end of sunflower growing season. Rhizosphere soil without herbicide application was used as a control. The herbicide was applied at the stage of 2–4 true leaves. The total number of bacteria in the rhizosphere of control plants was 12.82 million CFU/g of soil while in the rhizosphere and in the interrow soil after herbicide treatment with a dose of 2.5 l/ha it decreased by 1.4–1.5 times. A general trend of decline in number of the basic ecological and trophic groups of bacterial microorganisms with the increase in a dose of herbicide was established. Microbiological coefficients that reflect the functional activity of the microflora indicate changes in its biological activity under the influence of the herbicide Euro-Lightning Plus, which leads to deterioration in the agroecological state of the studied soils. It was also found that herbicide application resulted in a rearrangement of micromycete complexes in the root zone of sunflower which led to a two-fold reduction, compared to the control, of mycobiota species diversity and the formation of a specific species composition of mycocenoses. A greater genus and species diversity of fungi of the microflora in the rhizosphere of control plants, in comparison with the herbicide-treated soil, was revealed. A reduction in species diversity of the genus Penicillium from six species in the control to 1–2 species in the rhizosphere of experimental sunflower plants as well as the absence of rare saprophytic fungi species from the genera Acremonium, Verticillium, Trichoderma and Paecilomyces were noted.