Slurry transport in horizontal and vertical pipelines is one of the major means of transport of sands and gravels in the dredging industry. There exist 4 main flow regimes, the fixed or stationary bed regime, the sliding bed regime, the heterogeneous flow regime and the homogeneous flow regime. Of course the transitions between the regimes are not very sharp, depending on parameters like the particle size distribution. The focus in this paper is on the homogeneous regime. Often the so called equivalent liquid model (ELM) is applied, however many researchers found hydraulic gradients smaller than predicted with the ELM, but larger that the hydraulic gradient of liquid. Talmon (2011, 2013) derived a fundamental equation (method) proving that the hydraulic gradient can be smaller than predicted by the ELM, based on the assumption of a particle free viscous sub-layer. He used a 2D velocity distribution without a concentration distribution. In this paper 5 methods are described (and derived) to determine the hydraulic gradient in homogeneous flow, of which the last method is based on pipe flow with a concentration distribution. It appears that the use of von Driest (Schlichting, 1968) damping, if present, dominates the results, however applying a concentration distribution may neutralise this. The final equation contains both the damping and a concentration distribution giving the possibility to calibrate the constant in the equation with experimental data. The final equation is flexible and gives a good match with experimental results in vertical and horizontal pipelines for a value of ACv = 1.3. Data of horizontal experiments Dp = 0.05-0.30 m, d = 0.04 mm, vertical experiments Dp = 0.026 m, d = 0.125, 0.345, 0.560, and 0.750 mm.
Alongside climate change, the introduction of non-native species (NNS) is widely recognized as one of the main threats to aquatic biodiversity and human wellbeing. Non-native species and biodiversity are generally low priority issues on the political agendas of many countries, particularly in European countries outside the European Union (EU). The objectives and tasks of this study were to address the policy regulation, education level, education practices, and socioeconomic perceptions of NNS in the Balkans. A questionnairebased survey was conducted in Albania, Bosnia and Herzegovina, Montenegro, North Macedonia and Turkey (Balkan EU candidate and potential candidate members), in Croatia and Greece (Balkan EU Member States) and Italy (non-Balkan EU Member State). The EU Alien Regulation (1143/2014) concerning NNS is implemented in EU Member States and Montenegro, whereas Albania, Bosnia and Herzegovina and Turkey have not reported specific policy regulations for NNS. Permanent monitoring programmes specifically designed for NNS have not yet been established in the EU Member States. Most countries tackle the issue of NNS through educational activities as part of specific projects. Education level is indicative of the implementation of NNS policy regulation, and efforts are needed for the proper development of relative study programmes. Public awareness and educational preparedness concerning NNS in the Balkans were identified as poor. Strong programmes for management and education should be developed to increase public awareness to prevent further biodiversity losses in the Balkan region.
The African continent has a rich diversity of fish and amphibians in its inland water systems that serve as hosts for monogeneans of seven genera of the Gyrodactylidae van Beneden et Hesse, 1832. In August 2011, eight gyrodactylid parasites were collected from the gills of two specimens of bulldog, Marcusenius macrolepidotus (Peters), from Lake Kariba, Zimbabwe. Morphometric evaluation and sequencing of 18S rDNA confirmed that the specimens represented a species of a new viviparous genus, Tresuncinidactylus wilmienae gen. et sp. n. The attachment apparatus consists of a single pair of large slender hamuli with prominently flattened roots that are connected by a simple, narrow dorsal bar. The ventral bar is small and possesses a thin lingulate membrane but no evident anterolateral processes. There are 16 marginal hooks of one morphological type, but of three different sizes, with large falculate sickles that are proportionaly equal in length to the length of their handles. The two largest pairs of marginal hooks are positioned closest to the opisthaptoral peduncle, the neighbouring two pairs of medium-sized marginal hook sickles are situated along the lateral margins of the opisthaptor. Four pairs of smallest marginal hooks are positioned along the posterior margin of the opisthaptor. The male copulatory organ consists of a muscular pouch armed with approximately 30 gracile spines. Phylogenetic analyses of partial sequences of the 18S rDNA using Maximum Likelihood and Bayesian Inference placed the new genus within the lineage of solely African genera and suggests Afrogyrodactylus Paperna, 1968, Citharodactylus Přikrylová, Shinn et Paladini, 2017 and Mormyrogyrodactylus Luus-Powell, Mashego et Khalil, 2003 as genera most closely related to the new genus., Iva Přikrylová, Maxwell Barson, Andrew P. Shinn., and Obsahuje bibliografii
During the years 2019 and 2020, I conducted a bird survey transect in the Bohemian Forest. I did not record any changes in habitat structure or weather conditions between the two years. The two surveys differed in sampling effort, which was significantly lower in 2020 (n = 5 visits) than 2019 (n = 14 visits). I found that sampling effort affected the assessment of avian community diversity but did not affect the total number of individuals recorded. I also recorded a similar pattern in the cumulative number of species between the two breeding seasons, but 80% of species were recorded ten days earlier with the higher sampling effort. In the year with the lower sampling effort, I recorded fewer species than in the year with higher sampling effort. In both study periods, avian community diversity peaked during May and June. These results suggest that even a sampling effort three times lower is still sufficient to detect most species if the minimal number of visits are conducted. The pattern of detectability during the breeding season differed significantly among species. Most species (n = 24) showed a decreasing linear detectability throughout the summer months (e.g. Turdidae or Muscicapidae), most probably due to their breeding activities. In two species (willow tit Poecile montanus and European goldfinch Carduelis carduelis), this linear relationship was reversed, probably due to singing of young birds from the previous breeding season and the effect of the autumn equinox on birdsong activity. Many species (n = 21) did not show any trend and the rest, mainly migratory species, showed non-linear relationships with the peak in the middle of the breeding season. The differences in trends of detectability (i.e. song activity) among bird species are therefore directly linked with their life history.
This paper sums up the results of light microscopical, ultrastructural and molecular studies of five strains of amoeboid organisms isolated as endocommensals from coelomic fluid of sea urchins, Sphaerechinus granularis (Lamarck), collected in the Adriatic Sea. The organisms are reported as Didymium-like myxogastrids. Of the life-cycle stages, the attached amoeboids, flagellated trophozoites, cysts and biflagellated swarmers are described. Formation of fruiting bodies was not observed. Although phylogenetic analyses of SSU rDNA sequences indicated a close relationship with Hyperamoeba dachnaya, our sea-urchin strains have not been assigned to the genus Hyperamoeba Alexeieff, 1923. The presence of either one or two flagella reported in phylogenetically closely related organisms and mutually distant phylogenetic positions of strains declared as representatives of the genus Hyperamoeba justify our approach. Data obtained in this study may be useful in future analyses of relationships of the genera Didymium, Hyperamoeba, Physarum and Pseudodidymium as well as in higher-order phylogeny of Myxogastrea.
The diet composition and prey selection of grey wolves (Canis lupus) inhabiting the Roztocze and Solska Forest (south-east Poland) was studied based on an analysis of scats collected in 2001-2002 (n = 84) and 2017-2020 (n = 302). In both periods, wolves preyed mainly on wild ungulates (96.5-96.7% of consumed biomass). Roe deer (Capreolus capreolus) was the most critical wolf prey accounting for 57.8% of consumed biomass in 2001-2002 and 49.2% and 2017-2020, but wolves positively select only wild boar (Jacob's selectivity index D = 0.213 in 2001-2002 and 0.710 in 2017-2020) and fallow deer (D = 0.588 only in 2017-2020). The largest species – moose Alces alces and red deer Cervus elaphus – were consumed less than expected from their share in the ungulate community. Predation on medium-sized wild mammals and domestic animals was low, 0.8-2.2% and 1.1-2.7% of the biomass consumed, respectively. The breadth of the wolf diet was very narrow and identical in both study periods (B = 1.07), while the similarity of diet composition was high (α = 0.999). This study indicated the stability of the wolf diet over two decades and the importance of wild boar as a food source for this carnivore.
The age and growth of weatherfish (Misgurnus fossilis), an endangered and protected freshwater fish with a poorly known life history, was studied in two watercourses (the River Ner and the Nowy Rów canal, Poland). The weight, length and sagittal otoliths of 166 specimens collected in April 2015 were measured for weight-length relationships, ageing and back-calculation of length at age. At both sites sex ratio did not differ from 1:1. Weatherfish otoliths were small, elliptic (1.85 mm longer axes of the largest otolith) and the annuli were clearly visible. Female lifespan was six years but the oldest males were four and five years. In both sites populations were dominated by 2+ (the River Ner) and 3+ (the Nowy Rów canal) specimens. In general, weatherfish grows isometrically (b = 3) and the intercept of the weight-length relationship differ between study sites but not between sexes. Its total length (TL) was predicted by an interaction between sex and age, as well as capture site and age. Back-calculated estimates of TL fitted a von Bertalanffy growth function, though Taylor’s criterion showed that the asymptotic length were overestimated. Multiple comparisons of the von Bertalanffy growth function parameter revealed difference between sexes and sites.
Application of 6-benzylaminopurine (BAP) into cultivation medium of potato and tobacco plantlets caused changes in their growth, morphology and photosynthetic parameters in dependence on the plant species and the concentration ušed. The stimulating effect of BAP added to the cultivation medium was found only at very low BAP concentrations (up to 0.01 g m'^ in tobacco and 0.1 g m'^ in potato plantlets). BAP induced only a very slight tendency to increasing chlorophyll (Chl) a+b content and the ratios Chl alb, ChLcarotenoids and net photosynthetic rate/dark respiration rate {P^íIRd) in both plant species. Also the increase of the photochemical efficiency of photosystem 2 as indicated by the ratio of variable to maximal fluorescence (FyT^) and was not statistically significant and was found only in potato plantlets. The stomatal transpiration rate {E^ in tobacco plantlets increased with increasing BAP concentrations up to 0.1 g m'^. However, this was a rather negative effect as it increased a danger of plantlet wilting. In both plant species the BAP concentration of 1.0 g m-^ inhibited growth of plantlet roots; their shoots had altered morphology, their P^, light respiration rate {R\), E^, P^IRy, ratio, Chl contents and parameters of in vivo fluorescence (Fy/Fn,, qp, Rfd) decreased and CO2 compensation concentration increased. This negative effect of BAP was more pronounced in tobacco than in potato plantlets. The above mentioned changes in photosynthetic parameters in plantlets treated with BAP corresponded to the changes in photosynthetic parameters in transgenic plants of the same species with T-DNA carrying gene 4 and resulting from increased level of endogenous cytokinins. However, the application of BAP lead to a decrease in endogenous cytokinins level and thus the effects described are probably due to the action of BAP itself
Wolves are currently recolonising their historic range in France. The collection of scats is a widely used a non-invasive survey method to monitor wolf population size. However, seasonal changes in wolf faecal deposition patterns might affect the results of surveys. We used a detection dog and camera trapping (CT) to compare wolf scat detectability during winter and the nursing season. We collected 113 scats deposited by adult wolves at 29 marking sites on forest roads in the Sainte-Baume Regional Park, Provence, France. After parturition, the mean number of adult wolf scats increased by 160% inside the nursing territory and decreased by 80% outside of it. Around the time the pups are born, changes in faecal deposition patterns of adults make it easier to find scats around the wolf den (87% probability per wolf marking site) and harder to find scats outside the nursing territory (11% probability). During winter, the chance to find scats is equal (38 to 40% probability per wolf marking site) inside vs. outside the nursing territory. The combined use of a detection dog and camera traps allowed us to gather data on wolf defecation patterns non-invasively. Detectability of adult wolf scats during the nursing season is highly variable compared to winter due to seasonal behavioural changes affecting scat location. We conclude that surveys to collect samples and estimate wolf population size should be conducted exclusively during winter to avoid sampling biases.