Toxicity and genotoxic evaluations in African catfish Clarias gariepinus (Burchell 1822) exposed to Act Force Gold®, Butaforce®, and Atraforce®

Act Force Gold^®, Butaforce^®, and Atraforce^® are among the most commonly used pesticides in Nigeria. The lethal concentrations and the respective toxic units for the three pesticides were determined. The genotoxic effects of the three pesticides were investigated in the red blood cells of Clarias gariepinus using micronucleus (MN) assay. The 96 h LC₅₀ was 4.75, 4.84, and 54.74 mg L⁻¹ for Act Force Gold^®, Butaforce^®, and Atraforce^®, respectively. The toxic units in ascending order of toxicity were 1.83, 20.66, and 21.05 for Act Force Gold^®, Butaforce^®, and Atraforce^® respectively. The estimated safe levels based on NAS/NAE varied from 4.75 × 10⁻¹–4.75 × 10⁻⁵ in Act Force Gold^® through 4.64 × 10⁻¹–4.85 × 10⁻⁵ in Butaforce^® to 5.74–5.74 × 10⁻⁵ in Atraforce^®. Fish specimens were exposed to the pesticides and sampling was done at regular intervals at days 1, 7, 14, and 21 and after another 7-day recovery period. The results obtained indicated concentration- and duration-dependent increase in % MN formation with maximum values of 3.40 ± 0.25 for Act Force Gold^® on day 14 and 3.05 ± 0.36 and 2.35 ± 0.14 for Butaforce^® and Atraforce^® respectively on day 7 of exposure. The 7-day recovery period could not reverse the trend as the % MN values obtained were significantly different from the control. The results further support the use of MN assay in assessing the toxicity of aquatic pollutants and can be used in the monitoring of aquatic ecosystems.

     

Application of biomarkers to assess the condition of European Marine Sites

A series of European Marine Sites has been designated as Special Areas of Conservation (SAC) in England. The aim of this study was to develop a practical methodology to assess the condition of SACs by applying a suite of biomarkers. Biomarkers were applied to the blue mussel Mytilus edulis and the shore crab Carcinus maenas from the Fal and Helford SAC (Cornwall). Individual biomarkers provided useful diagnostic information on the activity of certain classes of contaminants and an integrated Biomarker Response Index (BRI) was used to achieve a more holistic understanding of the condition of the SAC. The BRI indicated that the general health of both organisms was impacted in the upper part of the SAC (Fal Estuary) which correlated well with known chemical hotspots and sources of contamination. The BRI allows a pragmatic way to prioritise SAC sites that may require further investigative studies.     

Larval outbreaks in West Greenland: Instant and subsequent effects on tundra ecosystem productivity and CO<Subscript>2</Subscript> exchange

Insect outbreaks can have important consequences for tundra ecosystems. In this study, we synthesise available information on outbreaks of larvae of the noctuid moth Eurois occulta in Greenland. Based on an extensive dataset from a monitoring programme in Kobbefjord, West Greenland, we demonstrate effects of a larval outbreak in 2011 on vegetation productivity and CO₂ exchange. We estimate a decreased carbon (C) sink strength in the order of 118–143 g C m^?2, corresponding to 1210–1470 tonnes C at the Kobbefjord catchment scale. The decreased C sink was, however, counteracted the following years by increased primary production, probably facilitated by the larval outbreak increasing nutrient turnover rates. Furthermore, we demonstrate for the first time in tundra ecosystems, the potential for using remote sensing to detect and map insect outbreak events.     

Oxygen Stratification in Industrial Boiler Stacks

The DSS/2 software system was used to numerically simulate oxygen stratification effects in a typical industrial boiler stack. The model developed for the simulation involves turbulent mass transfer in a tube with a constant, high mass flux from the walls of the tube. The concentration profile is considered to be developing, but the velocity profile is assumed to be fully developed. The model is for a gaseous system at constant temperature and pressure; the transport properties are shown to be constant. The universal velocity profile for turbulent flow and von Karman’s expressions for the turbulent eddy diffusivity are incorporated in the model. An expression for a wall concentration profile corresponding to conditions of high mass flux at the wall is developed. The model is then expressed as a system of partial differential equations which are solved using the numerical method of lines together with the DSS/2 numerical integration system. The resulting concentration profiles are presented for various flux rates which might be encountered in a typical stack. These profiles indicate that a potential for oxygen stratification in stacks does exist; they also suggest that careful placement of the oxygen cell probe can help minimize such errors.     

Social media and disasters: a functional framework for social media use in disaster planning,response, and research

A comprehensive review of online, official, and scientific literature was carried out in 2012–13 to develop a framework of disaster social media. This framework can be used to facilitate the creation of disaster social media tools, the formulation of disaster social media implementation processes, and the scientific study of disaster social media effects. Disaster social media users in the framework include communities, government, individuals, organisations, and media outlets. Fifteen distinct disaster social media uses were identified, ranging from preparing and receiving disaster preparedness information and warnings and signalling and detecting disasters prior to an event to (re)connecting community members following a disaster. The framework illustrates that a variety of entities may utilise and produce disaster social media content. Consequently, disaster social media use can be conceptualised as occurring at a number of levels, even within the same disaster. Suggestions are provided on how the proposed framework can inform future disaster social media development and research.     

Congenital limb deficiencies in newborn infants: prevalence,characteristics and prenatal diagnosis

Congenital limb deficiency (CLD) occurs in 0.54 to 0.59/1000 live-born infants and varies according to its anatomic location, type and cause. Our aim was to present a fetus with a prenatal ultrasonographic diagnosis of CLD (transverse reduction deficiency of the left upper limb), and to determine the prevalence and clinical characteristics of CLD at a tertiary medical centre in Israel. Among 78 500 live-born infants, there were 24 cases of CLD (0.31/1000): 45.8% of the CLD cases with affected upper limbs, 45.8% with affected lower limbs, and 8.4% with both limbs affected; 88.4% of the limb deficiencies were longitudinal and 11.6% were transverse; and, 33.3% (8/24) of the affected newborn infants had additional congenital anomalies. We conclude that CLD is not an infrequent finding in live-born infants. Comprehensive ultrasonography of the fetus allows early prenatal diagnosis of CLD and provides the parents with important information and helps them in their decision regarding the fate of the pregnancy. Copyright © 2003 John Wiley & Sons, Ltd.     

Mitochondrial DNA Variability in the Endangered Razorback Sucker (Xyrauchen texanus): Analysis of Hatchery Stocks and Implications for Captive Propagation

The razorback sucker ( Xyrauchen texanus ) is a large, long-lived catostomid fish endemic to the Colorado River drainage of western North America, endangered because of recruitment failure. Efforts to preserve the species have emphasized artificial propagation and reintroduction. Given the importance of maintaining genetic diversity in such a program, we examined mitochondrial DNA diversity in a source population (Lake Mohave, Arizona-Nevada) and three hatchery-produced year classes (1987, 1989, 1990). The source contained considerable variation, indicated by high haplotype diversity ( ĥ = 0.97) and a large number of unique haplotypes (17 in 25 individuals). Diversity also was high in the 1987 ( ĥ = 0.89, 6 haplotypes in 10 individuals) and 1989 hatchery-produced year classes ( ĥ = 0.91, 7 in 11), but significantly lower in the 1990 year class ( ĥ = 0.71, 4 in 10). Low diversity in the last class was likely because of differences among females in fecundity, viability of progeny, or both. Because natural populations have collapsed throughout the species' range, we must identify methods that preserve the most diversity. We examined three potential alternatives: standard hatchery propagation, natural spawning in predator-free environments, and protective custody of larvae collected from the lake with reintroduction after growth to a size likely to survive. The last is the preferred alternative and should be pursued as the most cost-effective option for preserving genetic diversity in the razorback sucker.