Abiotic factors

Abstract: The Galápagos Islands harbor some of the least impacted marine ecosystems in the tropics Efectos de la Pesca Artesanal en Comunidades Marinas en las Islas Galápagos Resumen: Las Islas Galápagos albergan algunos de los ecosistemas marinos menos afectados en los trópi-cos, pero hay indicios de que la pesca artesanal afecta a las comunidades marinas explotadas. Para cuantificar estos efectos, se muestrearon las comunidades de peces y erizos de mar en numerosos sitios con pesca intensiva y no intensiva en las islas centrales del archipiélago. Los sitios fueron seleccionados con base en la información colectada como parte de un estudio de monitoreo de pesquerías locales y estandarizada para diversos factores abióticos. La abundancia y la biomasa de las principales especies explotadas fue significativamente menor en los sitios con pesca intensiva versus no intensiva. La estructura de la comunidad también

ABSTRACT- The survival of indicator microorgan- isms in aquatic systems,is affected by both biotic and abiotic factors. Relatively little work in this field has been conducted,on the wide variety of sources of microorganisms,by using naturally occurring inocu- lants of microorganisms for study. Rates of inactiva- tion of water quality indicators, total coliforms, E. coli, enterococci, and male-specific coliphage were studied in three week-long, factorially designed experiments using three different inoculants: sewage,influent (to simulate a sewage spill), treated sewage effluent (to simulate chronic sewage discharges), and dry-weather urban runoff (to simulate non-point source discharges). Rates of inactivation were studied by examining the effects of temperature, nutrients, total suspended solids, initial bacterial load, and solar radiation in both natural fresh and seawater exposure matrices. Our results demonstrated,that temperature and solar radiation had significant effects upo...

The influence of temperature, light, salinity and nutrient availability on the release of volatile halogenated hydrocarbons was investigated in the Antarctic red macroalgal species Gymnogongrus antarcticus Skottsberg. Compared to standard culture condition, an increase in the release rates of iodocompounds was generally found for the exposure of the alga to altered environmental conditions. Macroalgae exhibited higher release rates after adaptation for two months to the changed factors, than after short-term exposure. Monitoring the release rates during a 24 h incubation period (8.25 h light, 15.75 h darkness) showed that changes between light and dark periods had no influence on the release of volatile halocarbons. Compounds like bromoform and 1-iodobutane exhibited constant release rates during the 24 h period. The formation mechanisms and biological role of volatile organohalogens are discussed. Although marine macroalgae are not considered to be the major source of biogenically-...

Various biotic or abiotic factors influence the fate of pesticides in the natural environment, of which ultraviolet (UV) component in the sunlight is one of the most powerful forces. Studies on the photodegradation of pesticides have not only significance from the point of view of environmental science, but also very important in researching and developing new, safer, and effective pesticides. Previously we have studied the photodegradation of triazine- and urea-type herbicides in details. This paper is intended to outline the photodegradation pattern of some commonly used N-containing herbicides that belong to the groups of the mentioned triazines (atrazine, cyanazine, terbuthylazine, terbutryn) and ureas (chloroxuron, methabenzthiazuron, diuron, fenuron), as well as thiolcarbamates (butylate, cycloate, EPTC, molinate, vernolate), in order to gain information about their possible fate and derivatives in the environment.The most significant processes of photodegradation of triazines are the partial or complete loss of side-chains, or rather the substitution of the heteroatom-containing side-chain to hydroxyl-group. The chemical characteristics of the side chains determines basically the speed of the degradation. It can be concluded that the C–S bond breaks down much easier than C–Cl bond, and the chlorine atom remaining on the triazine-ring promotes the loss of alkyl-chains to a higher extent than that the hydroxy-group. In the case of ureas, the chemical properties of groups in both the N and N′ position can influence the degradation process. It could be stated the proximity of large aryl-substituent and methyl-group in the N position is unfavorable and instabilizing, promoting the further degradation of compound, at the same time, loss of these groups is the preferred degradation route. In the case of thiolcarbamates, the most frequent processes are the α- and β-oxidation of alkyl-groups connecting to the nitrogen atom. In the most cases, the N-formyl and N-dealkylated products were identified in the degradation mixture. The thioalkyl-group showed fair stability under the circumstances of photodegradation. Its partly or completely degraded products cannot be detected, and represent only very small part of the mixture.

... Renata Perpetuo Reis & Yocie Yoneshigue-Valentin & C??sar Pereira dos Santos ... of the International Seaweed Symposium 15: 341???345 McCandless EL, Gretz MR (1984) Biochemical ... Reis RP, Barros-Barreto MB, Caldeira AQ Miranda APS (2005) Cultivo de algas vermelha de ...

Distributions of plant species over the earth's surface are neither random nor even, but are geographic specific and characterized by specific sets of environmental and climatic factors. The current study aimed to classify the vegetation along the River Panjkora of the district Dir Lower, Khyber-Pakhtunkhwa, Pakistan into different phytogeographic units via exercising the Multivariate statistical techniques. Vegetation sampling was carried out through quadrat quantitative ecological techniques. Quadrats of various sizes i.e. 1 × 1 m 2 , 5 × 5 m 2 and 10 × 10 m 2 were taken for herbs, shrubs and trees, respectively. Inclusively 215 plant species belong to 22 different phytogeographic elements were analysed and documented. The most dominant category of phytogeographic element was Irano-Turanian with 77 species, followed by Cosmopolitan 25 species, Holarctic 23 species, Pluriregional 19 species,

A simple and efficient protocol for the Agrobacterium-mediated transformation of an agronomically useful abiotic sensitive popular indica rice cv. ADT 43 has been developed. Initiation of calli were best achieved from the leaf bases of 4 days old rice seedlings on LS medium supplemented with 2.5mg/L 2,4-D and 1.0mg/L thiamine-HCl. Rice calli immersed in Agrobacterium suspension (strain EHA 105, OD(600)=0.8) were co-cultured on LS30-AsPC medium for 2 days at 25±2°C in the dark. Based on GUS expression analysis, 10min co-cultivation time with 100μM acetosyringone was found optimum for the delivery of gus gene. Calli were proved to be very sensitive to Agrobacterium infection and we found that the level of necrotic response can be minimized after co-cultivation with 30% LS, 10g/L PVP, 10% coconut water and 250mg/L timentin which improved the final transformation efficiency to 9.33%. Molecular and genetic analysis of transgenic plants reveals the integration, expression and inheritance of transgene in the progeny (T(1)) of these plants. The copy number of transgenes has been found to vary from 1 to 2 in transgenic plants (T(0) and T(1)).

The landscape of the southcentral part of Chile is dominated by fast-growing plantations of radiata pine (Pinus radiata D. Don), and in lesser extent bluegum eucalyptus (Eucalyptus globulus Labill.), Italian poplar, and willows. Radiata pine was first introduced in 1885 as an ornamental species. During 1940–1960 it was used to control erosion in the Coastal Range. Finally, since the 1960s it has been used for commercial plantations. The present extent of the plantation resource is 1,694,104 ha, of which 80.9 percent is radiata pine. During 1991, 1992, and 1993, this species was planted at rates of 75,416 ha, 81,868 ha, and 71,411 ha, respectively. Even though the soils are eroded to different degrees, exhibit a variety of nutritional disorders, and contain some physical restrictions, the productivity of radiata pine ranges from 18 m3/ha/yr to 35 m3/ha/yr. Additional stress comes from some potentially serious pests; for example, the European pine shoot moth, Rhyacionia buoliana, has presented a real threat to radiata pine. The main products obtained from radiata pine are exported to Japan, Korea, Middle and Far East countries, and Europe. Sawlogs, sawntimber, pulpwood, clearwood, and wood chips are some of the products comprising sales in 1994 of U.S.$1,564 billion. The purpose of this paper is to show how radiata pine silviculture has changed since the last part of the 1980s in Chile. Also we want to show how forestry activities have produced a profound and positive change in the social and economic environment that surrounds the areas where the industry’s main production areas exist.

The emerging literature on the ecotoxicity of nanoparticles and nanomaterials is summarised, then the fundamental physico-chemistry that governs particle behaviour is explained in an ecotoxicological context. Techniques for measuring nanoparticles in various biological and chemical matrices are also outlined. The emerging ecotoxicological literature shows toxic effects on fish and invertebrates, often at low mg l−1 concentrations of nanoparticles. However, data on bacteria, plants, and terrestrial species are particularly lacking at present. Initial data suggest that at least some manufactured nanoparticles may interact with other contaminants, influencing their ecotoxicity. Particle behaviour is influenced by particle size, shape, surface charge, and the presence of other materials in the environment. Nanoparticles tend to aggregate in hard water and seawater, and are greatly influenced by the specific type of organic matter or other natural particles (colloids) present in freshwater. The state of dispersion will alter ecotoxicity, but many abiotic factors that influence this, such as pH, salinity, and the presence of organic matter remain to be systematically investigated as part of ecotoxicological studies. Concentrations of manufactured nanoparticles have rarely been measured in the environment to date. Various techniques are available to characterise nanoparticles for exposure and dosimetry, although each of these methods has advantages and disadvantages for the ecotoxicologist. We conclude with a consideration of implications for environmental risk assessment of manufactured nanoparticles.