Retrospective analysis: bile hydrocarbons and histopathology of demersal rockfish in Prince William Sound,Alaska, after the Exxon Valdez oil spill

Demersal rockfish are the only fish species that have been found dead in significant numbers after major oil spills, but the link between oil exposure and effect has not been well established. After the 1989 Exxon Valdez oil spill in Prince William Sound, Alaska, several species of rockfish (Sebastes spp.) from oiled and reference sites were analyzed for hydrocarbon metabolites in bile (1989-1991) and for microscopic lesions (1990 and 1991). Biliary hydrocarbons consistent with exposure to Exxon Valdez oil were elevated in 1989, but not in 1990 or 1991. Significant microscopic findings included pigmented macrophage aggregates and hepatic megalocytosis, fibrosis, and lipid accumulation. Site differences in microscopic findings were significant with respect to previous oil exposure in 1991 (P=0.038), but not in 1990. However, differences in microscopic findings were highly significant with respect to age and species in both years (P<0.001). We conclude that demersal rockfish were exposed to Exxon Valdez oil in 1989, but differences in microscopic changes in 1990 and 1991 were related more to age and species differences than to previous oil exposure.     

A First Generation Stochastic Bioeconomic Analysis of Algal Bloom Control in a Coastal Lagoon (Sacca di Goro, Po River Delta)

Abstract. In this work we have developed a very simple stochastic mathematical model of Ulva spp. growth to quantitatively evaluate the economic costs of algal harvesting and the related benefits in terms of avoided'economic loss'of clam production due to an effective prevention of algal blooms and the consequent anoxic crises. Algal growth was simulated by means of a discrete time difference equation of Ulva biomass where the finite growth rate depends only upon water temperature. In order to explicitly include environmental variability, a seasonal autoregressive model calibrated on available data was used to simulate water temperature. Different harvesting scenarios were analysed in terms of the number of harvesting vessels employed and the threshold biomass of Ulva at which vessels start to operate. Costs of algal harvesting and disposal, as well as monetary damages resulting from the collapse of clam production as a consequence of algal blooms, were assessed by interviewing the managers of the Clam Fishermen's Union of Goro. A Monte Carlo approach was used to estimate the mean and total statistical distribution of costs and benefits of different harvesting strategies. Our analysis shows that the most cost-effective management policy is attained with 4–6 vessels operating at low algal density able to harvest as much Ulva as possible with intensive and short interventions at the beginning of the seasonal growth.     

DNA adducts in mussels and fish exposed to bulky genotoxic compounds

Biological and procedural factors can influence DNA adduct detection in aquatic organisms. Among them, functional structure and metabolic traits represent major biological determinants for adducts formed by lipophilic pro-mutagenic contaminants. In detecting DNA adducts through the 32P-postlabelling assay, efficiency in DNA purification, digestion, labelling, as well as adduct enrichment and quantification may explain differences between independent studies. Reference DNA adducts have been used to verify some 32P-postlabelling aspects. Data obtained for mussels and fish treated with benzo[a]pyrene (B[a]P) and environmentally exposed to genotoxins confirm the above assertions. Although the 32P-postlabelling assay cannot be proposed for routine biomonitoring it appears a reliable and very sensitive index of exposure to genotoxic pollutants in both fish and mollusks.     

Distribution of cacti in Larrea spp. shrublands in Mendoza, Argentina

In three Larrea shrublands, cacti grow under Larrea canopy at northern and southern exposures and in open spaces were counted. Cacti distribution was related to environmental variables. Seven out of the 15 cacti present were found to be associated with shrubs, whereas the other species were found in the open spaces. The lower temperature and radiation occurring under shrubs at south exposures would explain the absence of cacti in these places. The higher organic matter, nutrients, and moisture in the soils under shrubs appeared to be correlated with higher cacti density. The presence of cacti seedlings only under shrubs could be attributed to the favourable environmental conditions for cacti seed germination and seedling survival that occurred in these places.     

Biogeochemical Prospecting of Sulphide Minerals in Winder Valley, Balochistan, Pakistan

Abstract: The Mor Range is mountainous terrain in southern Balochistan dominantly occupied by exposures of rocks of the Ferozabad Group which is comprised of Lower‐Middle Jurassic carbonates and siliciclastics. This group contains syngenetic and epigenetic Zn–Pb–Ba mineralization classified as Stratiform Sediment‐Hosted (SSH) and Mississippi Valley Type (MVT) deposits. Three important flora of the Saharo–Sindian, phytogeographical region of Pakistan, namely Tamarix aphyl–la, Salvadora oleoides and Acacia arabica have been studied as a mineralization prospecting tool. Samples of these species were collected from Winder Valley adjoining the Mor Range to prospect for new areas of mineralization, besides the known sulphide deposits. This study revealed the Draber, Thorar, Raj, Mithi and Kanrach localities as new prospect. Quantitative estimation of biophile elements (Zn–Cu–Pb) from the three species was made. A number of new Zn, Cu and Pb anomalies were distinguished in the area. The variation in the constituents of these species from different localities possibly varies with nature and distance from bedrock, mobility, climate, average abundance in the plant ash and exclusion mechanism of the flora. Acacia arabica with deep penetrating roots shows the best results and could be used to delineate new horizons of mineralization. In these species Zn and Cu are relatively concentrated whereas Pb shows limited enrichment. Lead therefore is the element best suited for pinpointing the mineralization owing to its relatively less mobile character. Relationships among Zn–Cu–Pb have been established using scattergrams and triangular variation diagram, which also demonstrate their genetic affiliation. Statistical analyses, such as determination of mean, mode, median, standard deviation, and coefficient of correlation, were also made to improve the raw geochemical data. These biogeochemical methods appear to be suitable in arid climate of Balochistan, if proper attention is paid to species selection.     

Discrimination and classification of mangrove forests using EO-1 Hyperion data: a case study of Indian Sundarbans

In remote sensing the identification accuracy of mangroves is greatly influenced by terrestrial vegetation. This paper deals with the use of specific vegetation indices for extracting mangrove forests using Earth Observing-1 Hyperion image over a portion of Indian Sundarbans, followed by classification of mangroves into floristic composition classes. Five vegetation indices (three new and two published), namely Mangrove Probability Vegetation Index, Normalized Difference Wetland Vegetation Index, Shortwave Infrared Absorption Index, Normalized Difference Infrared Index and Atmospherically Corrected Vegetation Index were used in decision tree algorithm to develop the mangrove mask. Then, three full-pixel classifiers, namely Minimum Distance, Spectral Angle Mapper and Support Vector Machine (SVM) were evaluated on the data within the mask. SVM performed better than the other two classifiers with an overall precision of 99.08%. The methodology presented here may be applied in different mangrove areas for producing community zonation maps at finer levels.     

基于线粒体cyt b基因序列差异的组合PCR技术快速鉴定五种鳗鲡养殖种类的方法研究

在自然或人为因素下容易出现鳗苗种质混杂的现象,由于鳗鲡苗种在形态上十分相似,难以区分。为了保障鳗农的合法利益和提高养殖效益,急需建立一种能够在现场快速、高效使用的鳗鲡种质鉴定方法。本研究通过比对找出5种常见鳗鲡养殖种类:日本鳗鲡(Anguilla japonica)、美洲鳗鲡(A.rostrata)、花鳗鲡(A.marmorata)、太平洋双色鳗鲡(A.bicolor pacifica)、欧洲鳗鲡(A.anguilla)线粒体细胞色素B(cytochrome b,cyt b)基因的差异序列,基于5个cyt b基因序列差异较大的片段,设计多对引物,分别经过PCR验证和条件优化,挑选出4对引物:aj S1/A1、r-a S1/A2、bp-m S5/A3和m-a S4/A4。将这4对引物组合在同一个反应体系中进行PCR扩增,进行条件优化,筛选出组合PCR的最优条件:退火温度为58oC;退火时间为45s;循环数为27。结果表明,通过扩增产物凝胶电泳中条带的有无及大小可快速准确的鉴定出五个鳗鲡种类。本研究建立的组合PCR方法在3小时内可完成整个种类鉴定过程,同时可使用便携式小型仪器完成操作,可满足现场快速、高效鉴定的要求。此外,通过MEGA5.0软件构建5种鳗鲡线粒体cyt b基因序列NJ进化树,发现花鳗鲡和太平洋双色鳗鲡先聚为一支,再与日本鳗鲡聚在一起,而欧洲鳗鲡和美洲鳗鲡聚在一起,进化树图显示的遗传距离和它们的地理分布的远近相似。     

Relative change in stream discharge from a tropical watershed improves predictions of fecal bacteria in near-shore environments

Statistical models poorly predict bacteria in near-shore environments of tropical islands due to inaccuracies in runoff and discharge characterization of storm events. Intense, short duration storms on small, steeply sloped watersheds produce high rates of runoff, resulting in rapid pulses of discharge that influence the physical and physiological conditions of the fate and transport of pathogens. As such, increasing rates of discharge are expected to have a different influence on sediment transport and pathogen load compared to decreasing rates of discharge. Regression modeling was used to examine the affect of antecedent streamflow on the interaction between environmental parameters and two fecal indicator bacteria, enterococci and Clostridium perfringens. Including the relative change in discharge incorporates a proximate representation of the energy available to transport particulates, improving predictions of near-shore water quality. Understanding factors that influence pathogen loads improves management of watersheds and protects public health.