Loess and bee-eaters I : Ground properties affecting the nesting of European bee-eaters (Merops apiaster L.1758) in loess deposits

The European bee-eater (Merops apiaster L.1758) nests in tunnels in loess deposits. The properties of loess make it particularly suitable for tunnel nesting birds (a major factor is the metastable nature of the ground). The 'Heneberg Compromise' operates whereby the conflicting requirements of tunnel stability and ease of excavation dictate the optimum particle size for usable ground. The open structure of loess deposits, due to particle shape and airfall sedimentation, allows gas movement in nesting tunnels. It also allows local compaction during nest building which strengthens tunnel walls. The short range nature of the interparticle bonds in the ground material provides an almost ideal construction environment, ensuring a low plasticity index, which appears to be critical for tunnel building birds. Bee-eaters and sand martins dig tunnels in loess as 'primary nesters'. These loess tunnels are used by many 'secondary nesters'. The bee-eater is an efficient ecosystem engineer. Distribution maps of European bee-eater nesting, and of loess deposits, show some coincidence. A concentration of loess and nest regions is observed to the north of the Black Sea where the rivers Dnepr and Don deliver loess material, and to the west of the Black Sea in the Danube basin. The birds nest to the north of the demarcated Meigs arid/semi-arid zones in Africa, but spend winters to the south of these regions. They fly long distances from wintering zones to loess nesting regions, the longest migration of the bee-eaters. Even relatively minor loess deposits on the fringes of the breeding range, as in southern Poland, have their bee-eater inhabitants. © 2012 Elsevier Ltd and INQUA

Microcystin accumulation and potential effects on antioxidant capacity of leaves and fruits of Capsicum annuum

Surface water, often used for irrigation purposes, may sometimes be contaminated with blooming cyanobacteria and thereby may contain their potent and harmful toxins. Cyanotoxins adversely affect many terrestrial plants, and accumulate in plant tissues that are subsequently ingested by humans. Studies were undertaken to (1) examine the bioaccumulation of microcystins (MCs) in leaves and fruits of pepper Capsicum annuum and (2) examine the potential effects of MCs on antioxidant capacity of these organs. Plants were irrigated with water containing MCs for a period of 3 mo. Data showed that MCs did not accumulate in leaves; however, in fruits the presence of the MC-LR (0.118 ng/mg dry weight) and dmMC-LR (0.077 ng/mg dry weight) was detected. The concentrations of MC-LR in fruit approached the acceptable guideline values and tolerable daily intake for this toxin. Lipid peroxidation levels and flavonoids content were significantly enhanced in both organs of treated plants, while total phenolic concentrations were not markedly variable between control and treated plants. Significant decrease in 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging capacity was noted for both organs. The levels of superoxide anion in fruits and hydroxyl radical in leaves were markedly reduced. Data suggest that exposure to MCs significantly reduced antioxidant capacity of experimental plants, indicating that MCs affected antioxidant systems in C. annuum

Loess and Bee-Eaters II : The 'loess' of North Africa and the nesting behaviour of the Northern Carmine Bee-Eater (Merops nubicus Gmelin 1788)

The Northern Carmine Bee-Eater (Merops nubicus) lives and breeds in a well demarcated region stretching across Africa close to the 15°N line of latitude. The Bee-Eater zone appears to be associated with a band of loess, defined by Scheidig on his 1934 map as second-order loess. Bee-eaters are known to favour loess for nesting tunnels and it appears that the 15°N material is sufficiently loess-like. Obvious sources for particulate materials for the 15°N band are the Fonta-Djalon highlands which supply sedimentary material to the River Niger; the Bodele Depression, the deepest part of Lake Megachad, source of dust for the World; the Ethiopian highlands at the eastern end of 15°N which supply silt to the Nile system and particulates to the 15°N region. In soil moisture terms the region is ustic, which is possibly a necessary condition for bee-eater nests. The clastic material requires an ustic environment. The River Niger can be seen as a loess river; in some senses a mirror-image of a major loess river like the Danube; but where a restricted range of particle inputs leads to a restricted range of loess deposit outputs. Nevertheless loess river considerations can be applied. The Niger delivers second-order loess and an important loessic admixture to the landscape. Enough loess for selective nesters like the Carmine Bee-Eaters to build their nest tunnels in it. It seems likely that climate change will cause a change in bee-eater distribution; it seems unlikely that they will abandon their nesting regions, the living and wintering zones may shift

Loess and life out of Earth?

Loess is a homogeneous, typically nonstratified, porous, friable, slightly coherent, often calcareous, fine-grained, silty, pale yellow, wind blown (aeolian) and often by water reworked sediment that is distributed on continents world-wide. Recent studies have highlighted the importance of biological loess crusts in trapping and transforming aeolian material into loess and also in prevention from wind and water erosion of deposited material. Some planets and satellites in our solar system are characterized by conditions comparable to those related to loess formation in terrestrial environments. Given the requirements for loess deposition on Earth, this study aims to ask the following questions: 1) if loess-like sediment formation is possible outside Earth, what are the mechanisms of sediment deposition and preservation; 2) could the possible loess-like sediments be stabilized through the activity of extraterrestrial equivalents of biological loess crusts found on Earth? As loess formation on Earth is related to biological activity, we propose a new direction in the search for extraterrestrial life: evidence about extraterrestrial loess might indicate extraterrestrial life connected to loess formation. On the basis of comparative analysis of some astrophysical conditions of seven celestial bodies, we propose Mars and Titan, and possibly Venus and Io, to be assessed for evidence of loess deposition and the possible presence of related life forms and their biomarkers. Following recent advances in our understanding of terrestrial loess deposition we propose new indicators of extraterrestrial life research - biomarkers in loess (cyanobacterial and other microbial). (C) 2015 Elsevier Ltd and INQUA. All rights reserved

Protected freshwater ecosystem with incessant cyanobacterial blooming awaiting a resolution

© 2019 by the authors. For 50 years persistent cyanobacterial blooms have been observed in Lake Ludos (Serbia), a wetland area of international significance listed as a Ramsar site. Cyanobacteria and cyanotoxins can affect many organisms, including valuable flora and fauna, such as rare and endangered bird species living or visiting the lake. The aim was to carry out monitoring, estimate the current status of the lake, and discuss potential resolutions. Results obtained showed: (a) the poor chemical state of the lake; (b) the presence of potentially toxic (genera Dolichospermum, Microcystis, Planktothrix, Chroococcus, Oscillatoria, Woronichinia and dominant species Limnothrix redekei and Pseudanabaena limnetica) and invasive cyanobacterial species Raphidiopsis raciborskii; (c) the detection of microcystin (MC) and saxitoxin (STX) coding genes in biomass samples; (d) the detection of several microcystin variants (MC-LR, MC-dmLR, MC-RR, MC-dmRR, MC-LF) in water samples; (e) histopathological alterations in fish liver, kidney and gills. The potential health risk to all organisms in the ecosystem and the ecosystem itself is thus still real and present. Although there is still no resolution in sight, urgent remediation measures are needed to alleviate the incessant cyanobacterial problem in Lake Ludos to break this ecosystem out of the perpetual state of limbo in which it has been trapped for quite some time

Cyanobacteria, cyanotoxins, and their histopathological effects on fish tissues in Fehérvárcsurgó reservoir, Hungary

Cyanobacteria are important members of lake plankton, but they have the ability to form blooms and produce cyanotoxins and thus cause a number of adverse effects. Freshwater ecosystems around the world have been investigated for the distribution of cyanobacteria and their toxins and the effects they have on the ecosystems. Similar research was performed on the Fehérvárcsurgó reservoir in Hungary during 2018. Cyanobacteria were present and blooming, and the highest abundance was recorded in July (2,822,000 cells/mL). The species present were Aphanizomenon flos-aquae, Microcystis flos-aquae, Microcystis wesenbergii, Cuspidothrix issatschenkoi, Dolichospermum flos-aquae, and Snowella litoralis. In July and September, the microcystin encoding gene mcyE and the saxitoxin encoding gene sxtG were amplified in the biomass samples. While a low concentration of microcystin-RR was found in one water sample from July, analyses of Abramis brama and Carassius gibelio caught from the reservoir did not show the presence of the investigated microcystins in the fish tissue. However, several histopathological changes, predominantly in gills and kidneys, were observed in the fish, and the damage was more severe during May and especially July, which coincides with the increase in cyanobacterial biomass during the summer months. Cyanobacteria may thus have adverse effects in this ecosystem

Protected freshwater ecosystem with incessant cyanobacterial blooming awaiting a resolution

For 50 years persistent cyanobacterial blooms have been observed in Lake Ludoš (Serbia), a wetland area of international significance listed as a Ramsar site. Cyanobacteria and cyanotoxins can affect many organisms, including valuable flora and fauna, such as rare and endangered bird species living or visiting the lake. The aim was to carry out monitoring, estimate the current status of the lake, and discuss potential resolutions. Results obtained showed: (a) the poor chemical state of the lake; (b) the presence of potentially toxic (genera Dolichospermum, Microcystis, Planktothrix, Chroococcus, Oscillatoria, Woronichinia and dominant species Limnothrix redekei and Pseudanabaena limnetica) and invasive cyanobacterial species Raphidiopsis raciborskii; (c) the detection of microcystin (MC) and saxitoxin (STX) coding genes in biomass samples; (d) the detection of several microcystin variants (MC-LR, MC-dmLR, MC-RR, MC-dmRR, MC-LF) in water samples; (e) histopathological alterations in fish liver, kidney and gills. The potential health risk to all organisms in the ecosystem and the ecosystem itself is thus still real and present. Although there is still no resolution in sight, urgent remediation measures are needed to alleviate the incessant cyanobacterial problem in Lake Ludoš to break this ecosystem out of the perpetual state of limbo in which it has been trapped for quite some time