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showing 10 items of 4660 documents
Direct and indirect effects of sea ice cover on major zooplankton groups and planktivorous fishes in the Barents Sea
2019
AbstractReductions in Arctic sea ice affect marine food webs through a multitude of direct and indirect effects. We here analysed direct, indirect, and delayed associations between winter sea ice cover and year-to-year changes in biomasses of the main zooplankton groups (copepods, krill, amphipods) and planktivorous fishes (capelin, polar cod) in the central and northern Barents Sea from 1980 to 2015. Climate effects and species interactions were estimated jointly in a Bayesian state-space model framework. We found that population biomass of capelin increased in years with low sea ice cover, while biomasses of copepods and amphipods decreased. Furthermore, results suggested strong bottom-up…
Zooplankton species as indicators of trophic state in reservoirs from Mediterranean river basins
2019
Zooplankton abundance and composition is sensitive to eutrophication, and its top-down effect in the planktonic food web can alter the classification of the trophic state of waterbodies based on th...
Arctic sea ice algae differ markedly from phytoplankton in their ecophysiological characteristics
2021
Photophysiological and biochemical characteristics were investigated in natural communities of Arctic sea ice algae and phytoplankton to understand their respective responses towards variable irradiance and nutrient regimes. This study revealed large differences in photosynthetic efficiency and capacity between the 2 types of algal assemblages. Sea ice algal assemblages clearly displayed increased photoprotective energy dissipation under the highest daily average irradiance levels (>8 µmol photons m-2 s-1). In contrast, phytoplankton assemblages were generally light-limited within the same irradiance ranges. Furthermore, phytoplankton assemblages exhibited more efficient carbon assimilat…
Biogeography of arbuscular mycorrhizal fungal spore traits along an aridity gradient, and responses to experimental rainfall manipulation
2020
Abstract Spore size, colour and melanin content are hypothesised to be functional in relation to environmental stress. Here, we studied AM fungal spores in arid environments of Australia and in an experimental platform simulating altered rainfall. We used microscopy and image analysis to measure spore colour and size, and a quantitative colorimetric assay to estimate melanin content in spores. In arid sites, melanin content tended to increase with increasing aridity. We observed a large range of spore colours at all sites but found a higher proportion of both dark and light spores, and fewer intermediate colours, in drier sites. Spore abundance and size varied among sites, but neither were …
Proposal to Achieve Floodplain Connectivity in Alțâna Sector on Hârtibaciu River (Transylvania, Romania)
2016
Abstract The process of supplying water to the new anthropogenic wetland is achieved gravitationally, and the excess water in the wetland will be directed towards the Hârtibaciu River in a similar natural way. The fish and fauna of the Hârtibaciu River have a disrupted lateral connectivity due to its banks embanking including in the proximity of the Alţâna locality. The newly proposed anthropogenic wetland would improve habitat quality for the fish species of conservation interest, Rhodeus amarus (Bloch, 1782), and increase its population numbers. A new fish species, Chondrostoma nasus, was identified for the first time in the Hârtibaciu River.
Physiological Responses of Wetland Species Rumex Hydrolapathum to Increased Concentration of Biogenous Heavy Metals Zn and Mn in Substrate
2020
Abstract The aim of the present study was to determine if individuals of Rumex hydrolapathum Huds native to saline wetlands are able to tolerate high concentration of biogenous heavy metals Zn and Mn in substrate and to accumulate high concentration of these metals in aboveground parts. Plant physiological status was monitored by using non-destructive analysis of chlorophyll and chlorophyll a fluorescence. R. hydrolapathum plants accumulated up to 1840 mg·kg−1 Zn and 6400 mg·kg−1 Mn in older leaves. The usefulness of monitoring changes in chlorophyll concentration and chlorophyll a fluorescence parameters to predict physiological response of R. hydrolapathum plants to excess Zn and Mn was n…
The “Porţile de Fier/Iron Gates” Nature Park (Romania) Some Danube Northern Tributaries Fish Fauna
2014
Abstract The relative larger size of the Berzasca River, respectively the relatively constant environmental conditions, with relatively stenotopic ichthyocenosis, suffered small qualitative and quantitative fish fauna modifications in time, compared to the smaller rivers such as Sirinia, Liubcova/Oreviţa and Mraconia. The Danube “Iron Gates” I Lake influences the lower sectors of the studied rivers in term of fish species exchange. The accidental droughts in the karstic zones of the studied lotic sectors have a negative influence on the spatial continuity of the local fish fauna, and the climate change can increase these influence in the future. All the studied rivers play an important role…
<em>Centaurea inexpugnabilis</em>, una nueva especie de la sección <em>Acrocentron</em> para la flora ibérica
2017
Se describe una nueva especie para el género Centaurea L. (sect. Acrocentron, Asteraceae): C. inexpugnabilis, sp. nov. Esta planta ha sido localizada al pie de los Mallos de Riglos (Riglos, Huesca) y su distribución se circunscribe por el momento al cuadrante nororiental de la península ibérica. Junto a su descripción y diagnosis, se aporta una lámina y varias tablas con los principales caracteres diagnósticos que la diferencian de las especies más próximas.
The influence of thermal extremes on coral reef fish behaviour in the Arabian/Persian Gulf
2019
Despite increasing environmental variability within marine ecosystems, little is known about how coral reef fish species will cope with future climate scenarios. The Arabian/Persian Gulf is an extreme environment, providing an opportunity to study fish behaviour on reefs with seasonal temperature ranges which include both values above the mortality threshold of Indo-Pacific reef fish, and values below the optimum temperature for growth. Summer temperatures in the Gulf are comparable to those predicted for the tropical ocean by 2090–2099. Using field observations in winter, spring and summer, and laboratory experiments, we examined the foraging activity, distance from refugia and resting tim…
Restricted geographic distribution and low genetic distinctiveness of steppic Crioceris quinquepunctata (Coleoptera: Chrysomelidae) populations in Ce…
2019
Crioceris quinquepunctata is a European leafbeetle, rare and strictly associated with steppe-like habitats in Central and Eastern Europe. We sampled suitable localities in Central East Europe to determine the current distribution and to verify whether populations isolated by the Carpathian Mountains (within Pannonian and Pontic area) show genetic differentiation. Sequences from the beetle COI and ITSl were amplified and compared. Furthermore, ftsZ and hcpA genes of the endosymbiont Wolbachia were analysed as additional genetic markers. We found only two populations of C. quinquepunctata (in Moravia and Podolian Upland). Unusually low genetic differences between these populations were reveal…