Effects of mercury graded doses on redox status,metallothionein levels and genotoxicity in the intestine of sea cucumber Holothuria forskali

Mercury (Hg) is a ubiquitous and a major environmental metal pollutant in the aquatic ecosystem. The present study was performed to evaluate the effect of mercury graded doses exposure on oxidative stress, redox status, metallothionein levels and genotoxicity in the intestine of sea cucumber Holothuria forskali. Specimens were exposed for 96?h to three concentrations of Hg (40, 80 and 160?µg/L). Exposure of H. forskali to Hg promoted oxidative stress with an increase in malondialdehyde (MDA), protein carbonyl (PCO) and advanced oxidation protein products (AOPP) levels. An increase of glutathione (GSH), vitamin C (ViteC) and non-protein thiols (NPSH) contents was also observed. Additionally, antioxidant activities of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) increased especially with the highest doses of Hg indicating a great defense of the antioxidant system. Our investigation revealed an increase in total Metallothionein (MT) content which was more pronounced at the sharpest concentrations of Hg. A significant decline of AChE activity was also observed. In the intestine of Hg-treated H. forskali genotoxicity was confirmed by DNA degradation.     

Acute toxicity of aromatic and non-aromatic fractions of naphthenic acids extracted from oil sands process-affected water to larval zebrafish

The toxicity of oil sands process-affected water (OSPW) has regularly been attributed to naphthenic acids, which exist in complex mixtures. If on remediation treatment (e.g., ozonation) or on entering the environment, the mixtures of these acids all behave in the same way, then they can be studied as a whole. If, however, some acids are resistant to change, whilst others are not, or are less resistant, it is important to establish which sub-classes of acids are the most toxic.     

Some toxicological aspects op methamidophos exposure in mice 1

Abstract

Cholinesterase activity in the brain, RBC and plasma of Swiss mice was determined following different routes of administration of methamidophos. Continuous feeding with the insecticide caused a progressive inhibition of both plasma‐ and erythrocyte enzymes. The effect of methamidophos was more pronounced when applied in diet than when administered dermally or intraperitoneally. Following a single injection (i.p.) of methamidophos, the brain enzyme showed maximum inhibition 24 hr following treatment. At the appearance of tremors, the plasma and RBC‐enzymes showed considerable inhibition, the former being more inhibited. The plasma enzyme appears to be the most sensitive enzyme and may be taken as a suitable index for exposure to methamidophos.     

Approaches to Evaluating Climate Change Impacts on Species: A Guide to Initiating the Adaptation Planning Process

Assessing the impact of climate change on species and associated management objectives is a critical initial step for engaging in the adaptation planning process. Multiple approaches are available. While all possess limitations to their application associated with the uncertainties inherent in the data and models that inform their results, conducting and incorporating impact assessments into the adaptation planning process at least provides some basis for making resource management decisions that are becoming inevitable in the face of rapidly changing climate. Here we provide a non-exhaustive review of long-standing (e.g., species distribution models) and newly developed (e.g., vulnerability indices) methods used to anticipate the response to climate change of individual species as a guide for managers grappling with how to begin the climate change adaptation process. We address the limitations (e.g., uncertainties in climate change projections) associated with these methods, and other considerations for matching appropriate assessment approaches with the management questions and goals. Thorough consideration of the objectives, scope, scale, time frame and available resources for a climate impact assessment allows for informed method selection. With many data sets and tools available on-line, the capacity to undertake and/or benefit from existing species impact assessments is accessible to those engaged in resource management. With some understanding of potential impacts, even if limited, adaptation planning begins to move toward the development of management strategies and targeted actions that may help to sustain functioning ecosystems and their associated services into the future.     

The dynamics of dissolved nitrogen in a blanket peat dominated catchment

Precipitation, soil solution and drainage water were collected from a blanket peat catchment at Moor House National Nature Reserve in the Northern Pennine Uplands, UK, an area of moderately high N deposition. Two tributaries of the main stream were also sampled. Between 1993 and 1995 samples were analysed for NH4+ and NO3- and for part of the period for organic N. Inputs of N in precipitation exceeded outputs in stream water. Organic N represented a small proportion of N inputs while inputs of inorganic N averaged 10.2 kg ha(-1) a(-1). Soil solution from 10 cm depth in the peat was dominated by organic N whereas at 50 cm NH4+ slightly exceeded organic N. NO3- was rarely detected at either depth except during a period of exceptionally warm and dry weather in 1995. Output fluxes in stream water of organic N (5.7 to 6.5 kg ha(-1) a(-1)) were much greater than those of inorganic N (0.6 to 2.2 kg ha(-1) a(-1)). Inorganic N in streams was predominantly NO3- except in the smallest stream which had the largest concentrations of NH4+. This suggests that N transformations, particularly nitrification, may be taking place in the mineral soils adjacent to the streams or within the stream channel of the larger catchment.     

Diurnal vertical migration of an estuarine cladoceran,Podon polyphemoides,in the Chesapeake Bay

Populations of the marine cladoceran Podon polyphemoides (Leuckart) in the Chesapeake Bay (USA) zooplankton typically occur in large patches, extending the length of the estuary. These patches are characterized by well defined maxima, which do not move seaward during a given season. During the day, the bulk of the population is situated in the upper part of the two-layered estuarine circulation, where it is subjected to transport by net non-tidal seaward current. One mechanism for maintaining the population within the estuary is provided by the diurnal behavior of the podonids, which migrate to deeper water during the night. The landward advection of the deeper currents, thus, helps to counterbalance seaward population loss during the day. The extent of the vertical movement of the population can be modified by various environmental factors, but a suggestive correlation with light was found. It is thought that the downward component of the migration is due to passive sinking.     

VILLAGE DEMONSTRATION OF BIOGAS TECHNOLOGY: AN EGYPTIAN CASE STUDY

Within the context of biogas R & D and demonstration project undertaken by the Egyptian National Resarch Centre, village demonstrations are of paramount importance. In this paper, a case study of a pioneering village demonstration is presented. Based on a preliminary sociological survey, “Al Manawat” - a traditional Egyptian village was selected for the first demonstration. After a short orientation phase through which the biogas technology was introduced to a group of village representatives, a family was selected to conduct the demonstration experiment. Concomitant with the family energy requirements, availability of digester feed materials, site characteristics and other relevant factors, a family-size unit of a modified Indian type was designed and erected by the side of the farmer's house. The digester effective volume is 9 cu.m. and is connected to both a latrine and animal shed. The unit has been successfully operated since May 1981. The highlights of the construction stage as well as the unit performance characteristics are discussed. A preliminary techno-economic appraisal is also outlined. Finally, social impacts are assessed. Initial results indicate that under the Egyptian village conditions, and particularly with the heavily subsidized fuel prices, the high saving in manure transport attained through the introduction of the biogas unit, appears to be the main benefit from the farmer's point of view. Dans le cadre de la recherche et du développement du gaz de fermentation et d'un projet pilote entrepris par le Centre national de recherche égyptien, les démonstrations faites dans les villages occupent une place prépondérante. Dans cet article, l'auteur présente le cas-type d'une démonstration pilote faite dans un village. En se basant sur une enquêue sociologique préliminaire, “Al Manawat”, qui est un village égyptien traditionnel, a été choisi comme lieu de la première démonstration. Après une courte phase d'orientation au cours de laquelle le technologie du gaz de fermentation a été présentée à un groupe de notables du village, on a choisi une famille pour effectuer la démonstration expérimentale. En même temps que l'on étudiait les besoins énergétiques de cette famille, la disponibilité de matières de base de fermentation, les caractéristiques de l'emplacement et tous autres facteurs pertinents, une unité familiale de type indien modifié a été con?ue et érigée à côté de la ferme. Le composteur, d'un volume utile de matières premières de 9 m³, est relié à la fois aux latrines et à l‘étable. Cette unité fonctionne avec satisfaction depuis le mois de mai 1981. L'article met en avant les points essentiels des étapes de la construction et les caractéristiques de rendement de l'unité de fermentation. Il esquisse une évaluation technico-économique préliminaire et fait l'estimation des retombées sociales. Les premiers résultats montrent que, dans le cadre du village égyptien et particulièrement du fait que les prix du fuel sont largement subventionnés, les économies importantes réalisées dans le transport du fumier grâce á l'introduction de l'unité de fermentation semblent étre, du point de vue du fermier, le bénéfice principal. Dentro del contexto del proyecto de I & D y demostración realizado por el Centro de Investigación Nacional de Egipto, la demostración en los villorrios es de suma importancia. Este artículo presenta un caso pionero de este tipo. Basado en encuestas sociológicas, un villorrio tradicional de Egipto, “Al Manawat” fue selectiondo para la primera demostración. Después de una fase corta de orientación en la que se introdujo la tecnologia del biogás a los representantes del villorrio, se seleccionó una familia con cuya colaboración se Ilevaria a cabo el experimento. Teniendo en cuenta las necesidades de energia de la familia, la disponibilidad de materia prima para el digestor, las caracter ísticas del lugar y otros factores importantes, se diseñó y construyó un digestor de tamaño familiar, usando un modelo Indio, al lado de la casa de la familia. El volumen efectivo del digestor es 9 metros cúbicos y está conectado a la letrina y al corral de animales. La unidad está funcionando con éxito desde Mayo de 1981. Se discuten aspectos de la etapa de construcción y las características de operación. Se hace también una evaluación técnico-económica preliminar. Finalmente se evalúa el impacto social de la experiencia. Los resultados indican que en las condiciones de los villorrios Egipcios, especialmente en condiciones de precios de combustibles altamente sub-sidiados, los grandes ahorros en el transporte de abono debido a la introducción del digestor de biogas parece ser el mayor beneficio desde el punto de vista de la familia.     

A model of a wasp colony population, Paravespula vulgaris (L.)

A model has been developed which predicts the numbers of immature and adult workers, males and queens, in a Paravespula vulgaris colony throughout a season. This model colony is based on the rate of egg lay of the queen which is approximated by a skewed normal frequency curve. Larval and pupal numbers are predicted by applying mean developmental times to the eggs produced. For workers, adult numbers are produced by modifying pupal numbers by adult longevity, while adult males and queens are obtained directly from their respective pupal numbers. Data generated by the model compare favourably with published observations.Changes in the larva : worker ratio through the season affecting adult longevity and immature stage developmental times are discussed. The total number of adults produced per worker (Ro) varies throughout the season following a skewed normal frequency distribution. Adult queens and males accounted for only 15% of the total seasonal egg production.This model could easily be adapted to deal with population changes in colonies of other eusocial wasps.