Interactive effects between water temperature, microparticle compositions, and fiber types on the marine keystone species Americamysis bahia.

Recently, there has been an increasing emphasis on examining the ecotoxicological effects of anthropogenic microparticles (MPs), especially microplastic particles, and related issues. Nevertheless, a notable deficiency exists in our understanding of the consequences on marine organisms, specifically in relation to microfibers and the combined influence of MPs and temperature. In this investigation, mysid shrimp (Americamysis bahia), an important species and prey item in estuarine and marine food webs, were subjected to four separate experimental trials involving fibers (cotton, nylon, polyester, hemp; 3 particles/ml; approximately 200 µm in length) or fragments (low-density Polyethylene: LDPE, polylactic acid: PLA, and their leachates; 5, 50, 200, 500 particles/ml; 1-20 µm). To consider the effects in the context of climate change, three different temperatures (22, 25, and 28 °C) were examined. Organismal growth and swimming behavior were measured following exposure to fragments and microfibers, and reactive oxygen species and particle uptake were investigated after microfiber exposure. To simulate the physical characteristics of MP exposure, such as microfibers obstructing the gills, we also assessed the post-fiber-exposure swimming behavior in an oxygen-depleted environment. Data revealed negligible fragment, but fiber exposure effects on growth. PLA leachate triggered higher activity at 25 °C and 28 °C; LDPE exposures led to decreased activity at 28 °C. Cotton exposures led to fewer behavioral differences compared to controls than other fiber types. The exposure to hemp fibers resulted in significant ROS increases at 28 °C. Microfibers were predominantly located within the gastric and upper gastrointestinal tract, suggesting extended periods of residence and the potential for obstructive phenomena over the longer term. The combination of increasing water temperatures, microplastic influx, and oxidative stress has the potential to pose risks to all components of marine and aquatic food webs.

Integrative phylogenetic, phylogeographic and morphological characterisation of the Unio crassus species complex reveals cryptic diversity with important conservation implications.

The global decline of freshwater mussels and their crucial ecological services highlight the need to understand their phylogeny, phylogeography and patterns of genetic diversity to guide conservation efforts. Such knowledge is urgently needed for Unio crassus, a highly imperilled species originally widespread throughout Europe and southwest Asia. Recent studies have resurrected several species from synonymy based on mitochondrial data, revealing U. crassus to be a complex of cryptic species. To address long-standing taxonomic uncertainties hindering effective conservation, we integrate morphometric, phylogenetic, and phylogeographic analyses to examine species diversity within the U. crassus complex across its entire range. Phylogenetic analyses were performed using cytochrome c oxidase subunit I (815 specimens from 182 populations) and, for selected specimens, whole mitogenome sequences and Anchored Hybrid Enrichment (AHE) data on âˆ¼ 600 nuclear loci. Mito-nuclear discordance was detected, consistent with mitochondrial DNA gene flow between some species during the Pliocene and Pleistocene. Fossil-calibrated phylogenies based on AHE data support a Mediterranean origin for the U. crassus complex in the Early Miocene. The results of our integrative approach support 12 species in the group: the previously recognised Unio bruguierianus, Unio carneus, Unio crassus, Unio damascensis, Unio ionicus, Unio sesirmensis, and Unio tumidiformis, and the reinstatement of five nominal taxa: Unio desectusstat. rev., Unio gontieriistat. rev., Unio mardinensisstat. rev., Unio nanusstat. rev., and Unio vicariusstat. rev. Morphometric analyses of shell contours reveal important morphospace overlaps among these species, highlighting cryptic, but geographically structured, diversity. The distribution, taxonomy, phylogeography, and conservation of each species are succinctly described.

Dietary exposure to four sizes of spherical polystyrene, polylactide and silica nanoparticles does not affect mortality, behaviour, feeding and energy assimilation of Gammarus roeseli.

The abundance and persistence of plastic nanoparticles in aquatic habitats are considered a threat to marine and freshwater biota. However, the risk assessment of plastic particles is complicated due to various factors that need to be considered, including composition, size and environmental abundance. This study investigated the behavioural response of a key river species, Gammarus roeseli, to dietary exposure of plain biodegradable and non-biodegradable plastic as well as to natural small micro- and nanoparticles. Mortality, feeding, swimming velocity and energy assimilation endpoints were examined by considering four particles sizes ranging from 30 to 1000 nm in two concentrations. Contrary to our expectations, neither decreasing size nor increasing abundance of each tested particle impacted any of the examined endpoints. Likewise, dietary exposition with biodegradable plain polylactide did not induce other or stronger effects than non-biodegradable plain polystyrene or natural silica micro- and nanoparticles, as all three particle types did not lead to adverse effects on G. roeseli. These findings also suggest that the functional role of Gammarus roeseli as a shredder is not impaired due to particle occurrence within the exposure range of this study.

Impact of catchment land use on fish community composition in the headwater areas of Elbe, Danube and Main.

Intensification of catchment land-use and the corresponding habitat degradation pose a threat to freshwater biodiversity and ecosystem health, yet few studies comprehensively quantified the effects of specific land-use variables on fish communities for different catchments within the same climatic region. Herein, we investigated the influence of catchment land use on fish community composition in the headwater areas of the European main river systems Elbe, Danube and Main/Rhine. The analyses comprising 289 streams and rivers in Bavaria, southern Germany, revealed that the influence of urbanization (e.g. ground sealing), potamalisation (impoundment of water courses), and erosion-prone, agricultural land-use types (e.g. root crop, maize) were significantly related to the fish community composition. In addition, multiple stressors were effective indicators and their importance differed between survey-area scales, geographical regions, and stream sizes. The findings suggest that terrestrial effects of land-use and urbanization need to be more strongly considered in the conservation of endangered stream fishes, ideally including combined measures of erosion control, restoration of environmental flows and mitigation of structural degradation.

Comparison of nine different methods to assess fish communities in lentic flood-plain habitats.

This study compares the effectiveness and representativeness of electrofishing, snorkelling, seining, baited lift netting, multi-mesh gillnetting, baited fish traps, fyke netting, angling and longline fishing, considering three typical lentic flood-plain habitats at different times of day. Electrofishing was by far the most effective method yielding highest species richness, species trait representation and catch per unit of effort (CPUE), followed by seining. For single species like dace Leuciscus leuciscus, European ruffe Gymnocephalus cernua, common bream Abramis brama and silver bream Blicca bjoerkna, seining was more effective than electrofishing. With both methods, some species were more consistently caught during night, dusk or dawn than during daylight. All other methods tested cannot be generally recommended for fish community assessments in shallow backwaters due to their low representativeness of species inventory and generally low CPUE. Based on these results, electrofishing of 30 m transect replicates at different times of day for monitoring the fish community in shallow backwaters, can be recommended, enabling the maximum possible comparability to adjacent river habitats. Seining should be considered as an alternative if accessibility of habitats is restricted or electrofishing is prohibited. The 25 species detected in the backwaters also suggest that these habitats contribute a large proportion of fish diversity and should be included in standard assessments of river ecological status.

Synergistic impacts by an invasive amphipod and an invasive fish explain native gammarid extinction.

BACKGROUND: Worldwide freshwater ecosystems are increasingly affected by invasive alien species. In particular, Ponto-Caspian gobiid fishes and amphipods are suspected to have pronounced effects on aquatic food webs. However, there is a lack of systematic studies mechanistically testing the potential synergistic effects of invasive species on native fauna. In this study we investigated the interrelations between the invasive amphipod Dikerogammarus villosus and the invasive fish species Neogobius melanostomus in their effects on the native amphipod Gammarus pulex. We hypothesized selective predation by the fish as a driver for displacement of native species resulting in potential extinction of G. pulex. The survival of G. pulex in the presence of N. melanostomus in relation to the presence of D. villosus and availability of shelter was analyzed in the context of behavioural differences between the amphipod species. RESULTS: Gammarus pulex had a significantly higher susceptibility to predation by N. melanostomus compared to D. villosus in all experiments, suggesting preferential predation by this fish on native gammarids. Furthermore, the presence of D. villosus significantly increased the vulnerability of G. pulex to fish predation. Habitat structure was an important factor for swimming activity of amphipods and their mortality, resulting in a threefold decrease in amphipods consumed with shelter habitat structures provided. Behavioral differences in swimming activity were additionally responsible for higher predation rates on G. pulex. Intraguild predation could be neglected within short experimental durations. CONCLUSIONS: The results of this study provide evidence for synergistic effects of the two invasive Ponto-Caspian species on the native amphipod as an underlying process of species displacements during invasion processes. Prey behaviour and monotonous habitat structures additionally contribute to the decline of the native gammarid fauna in the upper Danube River and elsewhere.

Centroid precision and orientation precision of planar localization microscopy.

The concept of localization precision, which is essential to localization microscopy, is formally extended from optical point sources to microscopic rigid bodies. Measurement functions are presented to calculate the planar pose and motion of microscopic rigid bodies from localization microscopy data. Physical lower bounds on the associated uncertainties - termed centroid precision and orientation precision - are derived analytically in terms of the characteristics of the optical measurement system and validated numerically by Monte Carlo simulations. The practical utility of these expressions is demonstrated experimentally by an analysis of the motion of a microelectromechanical goniometer indicated by a sparse constellation of fluorescent nanoparticles. Centroid precision and orientation precision, as developed here, are useful concepts due to the generality of the expressions and the widespread interest in localization microscopy for super-resolution imaging and particle tracking.

A cone beam CT investigation of ponticulus posticus and lateralis in children and adolescents.

OBJECTIVES: To determine the prevalence and pathogenesis of ponticulus posticus (PP) and ponticulus lateralis (PL) in children and adolescents. METHODS: Cone beam CT scans of 576 patients were examined for PP and PL. The patients were divided into three age groups: 10 years and younger, 11-13 years and 14 years and older. Ponticulus formation was categorized as absent, partial or complete. Gender, race and location (right, left or bilateral) were recorded. Data were analysed with the χ(2) test, with significance at p < 0.050. Institutional review board approval was granted. RESULTS: Overall prevalence of PP was 26.2%, with complete lesions in 10.4%. The frequency of PP was greater in patients aged 14 years and older (p ≤ 0.038). The occurrence of complete PP was greater in patients aged 11 years and older (p = 0.028). Lesions were more common in males (p = 0.014) and in blacks compared with other non-white races (p = 0.035). Bilateral PP was more common than right-sided lesions (p = 0.008) and more frequent in the oldest cohort (p = 0.006). Overall prevalence of PL was 6.1% (3.0% complete), with no differences between age groups, genders, races or by location. CONCLUSIONS: PP is not uncommon even in the first decade and increases in frequency, completeness of calcification and numbers in mid-adolescence. It appears to be more common in males and in blacks. PP may be a congenital osseous anomaly of the atlas that mineralizes at various times. PL is less frequent with no demographic predilections.

Genetic diversity of upper Lake Constance whitefish Coregonus spp. under the influence of fisheries: a DNA study based on archived scale samples from 1932, 1975 and 2006.

This investigation examined changes in the genetic diversity of pelagic upper Lake Constance (ULC) whitefish Coregonus wartmanni population before and after the alteration of fishery methods and management from 1932 to 2006. The study spans a period of pronounced changes in trophic status of the lake and transitions from traditional relatively unselective pelagic seine (Klusgarn) fishing to highly size-selective nylon gillnet techniques. In addition, supportive breeding and stocking became most popular during the phase of eutrophication in the 1970s. The main hypothesis is that size-selective fisheries and breeding lead to an overall decrease in genetic variability over time. A total of 215 archived C. wartmanni scale samples from 1932, 1975 and 2006 were analysed by genotyping 11 microsatellite loci. A comparison of population genetic parameters, including allelic richness, observed and expected heterozygosities, and estimates of effective population sizes, suggests that the genetic diversity of C. wartmanni population has not decreased. The appearance of new alleles in the gene pool in 1975 and 2006 may be indicative of admixture with other forms in the lake or with stocked allochthonous forms. Overall, the fisheries management practice in ULC, including the effects of size-selective fisheries, supportive breeding and stocking, have not significantly altered the genetic diversity of Coregonus spp. over an 80 year period.

Effects of sampling techniques on population assessment of invasive round goby Neogobius melanostomus.

In this study, a comparison of point abundance sampling (PAS) electrofishing, angling with two different hook sizes and trap-based fishing was performed in a non-wadeable river to analyse their effects on catch per unit effort (CPUE) and population characteristics of invasive round goby Neogobius melanostomus. PAS electrofishing was identified as the most effective (mean ± s.e. CPUE = 57 ± 4 N. melanostomus min(-1) ) and least selective method in terms of size, feeding status and species composition. Angling had the second highest CPUE, but was more size selective and resulted in a higher proportion of males compared to electrofishing [overall sex ratio angling (female:male) = 1:0.92, electrofishing 1:0.65]. Owing to low CPUE (0.012 ± 0.004) and low frequency of occurrence, minnow traps were least suitable for N. melanostomus population assessment. The results of this study suggest that a higher degree of standardization and inter-calibration is useful to achieve better comparability of population data of invasive N. melanostomus and other benthic fish species.

First evidence for interspecific hybridization between invasive goby species Neogobius fluviatilis and Neogobius melanostomus (Teleostei: Gobiidae: Benthophilinae).

Two hybrids between the monkey goby Neogobius fluviatilis and the round goby Neogobius melanostomus from the Rhine River were identified by genotyping and morphological comparison. These are the first records of goby-hybrids outside the parent species' native ranges worldwide.

Microhotplate Temperature Sensor Calibration and BIST.

In this paper we describe a novel long-term microhotplate temperature sensor calibration technique suitable for Built-In Self Test (BIST). The microhotplate thermal resistance (thermal efficiency) and the thermal voltage from an integrated platinum-rhodium thermocouple were calibrated against a freshly calibrated four-wire polysilicon microhotplate-heater temperature sensor (heater) that is not stable over long periods of time when exposed to higher temperatures. To stress the microhotplate, its temperature was raised to around 400 °C and held there for days. The heater was then recalibrated as a temperature sensor, and microhotplate temperature measurements were made based on the fresh calibration of the heater, the first calibration of the heater, the microhotplate thermal resistance, and the thermocouple voltage. This procedure was repeated 10 times over a period of 80 days. The results show that the heater calibration drifted substantially during the period of the test while the microhotplate thermal resistance and the thermocouple-voltage remained stable to within about plus or minus 1 °C over the same period. Therefore, the combination of a microhotplate heater-temperature sensor and either the microhotplate thermal resistance or an integrated thin film platinum-rhodium thermocouple can be used to provide a stable, calibrated, microhotplate-temperature sensor, and the combination of the three sensor is suitable for implementing BIST functionality. Alternatively, if a stable microhotplate-heater temperature sensor is available, such as a properly annealed platinum heater-temperature sensor, then the thermal resistance of the microhotplate and the electrical resistance of the platinum heater will be sufficient to implement BIST. It is also shown that aluminum- and polysilicon-based temperature sensors, which are not stable enough for measuring high microhotplate temperatures (>220 °C) without impractically frequent recalibration, can be used to measure the silicon substrate temperature if never exposed to temperatures above about 220 °C.

Salmonid-egg floating boxes as bioindication for riverine water quality and stocking success.

The salmonid-egg floating box provides an easy bioindication tool for an assessment of water quality, as demonstrated here for the reintroduction of Europe's largest salmonid species, the huchen Hucho hucho.

The 'egg sandwich': a method for linking spatially resolved salmonid hatching rates with habitat variables in stream ecosystems.

This paper describes the development of the 'egg sandwich', a system for assessing stream substratum quality by linking measurements of depth-specific salmonid egg hatching success and physico-chemical water variables from the same sites within the interstitial zone.

The importance of genetic cluster recognition for the conservation of migratory fish species: the example of the endangered European huchen Hucho hucho (L.).

European huchen Hucho hucho (L.) is an endangered flagship species, which is endemic to the Danube drainage in central Europe. To date, no genetic information has been available as a basis for ongoing conservation and breeding programmes for the species. It is suspected that most populations in the wild share one common gene pool and that they exclusively depend on stocking with hatchery fish. In this study, highly variable microsatellite markers were established and the genetic diversity and differentiation from four important hatchery-reared stocks were compared with that of eight H. hucho populations sampled in the wild. Overall, eight genetic clusters with a moderate to very great degree of genetic differentiation and high assignment rates were identified. Each cluster contained individuals from two to 10 different populations and 9-100% of specimens from hatchery stocks. It is proposed that genetic cluster-based management in the conservation of European huchen is advantageous compared with the consideration of single local populations. A combined approach of maintaining the evolutionary potential of wild populations and genetically variable hatchery stocks can maximize the conservation of the species' evolutionary potential.

Osteosarcoma of the jaws in children.

Two cases of osteosarcoma of the jaws in children are reported. One patient was a 13-year-old girl whose first symptoms included nasal and maxillary sinus congestion, followed by epistaxis. She was found to have chondroblastic osteosarcoma extending through the left maxillary alveolar process and sinus. Following surgery and chemotherapy, the patient has been free of disease for 7 years. The second patient, an 8-year-old boy, was diagnosed with juxtacortical (parosteal) osteosarcoma of the mandible, which is a less aggressive variant of the neoplasm. It is believed that this is the youngest patient reported to date with juxtacortical osteosarcoma of the jaws. He was treated by block resection of the right side of the mandible and is free of disease 3(1/2) years later.