Assessing of Environmental Quality in Six Areas in India,Sri Lanka and Bangladesh

Environmental quality for environmental health has been examined visually by describing general conditions and drinking water supply, sanitation and solid waste treatment conditions and practices in six South-East Asian villages with a dense population. The environmental review was supplemented by discussions with local people and political and administrative decision makers. Some drinking water analyses were done in order to show the water quality to the local people. The quality of the general conditions and the conditions and practices of drinking water supply, excreta disposal and solid waste treatment practices have been graded with the grading system presented below. The grading could be done in 1 or 2 days in each area by two persons, of which one was an environmental scientist and the other a social scientist, who also knew the local culture and worked as a translator.     

The impact of coal utilization in Texas under the National energy plan

The paper describes the results of a study of the impact of the National Energy on the trend towards increased utilization of coal and lignite in Texas with forecasts of increased coal and lignite utilization for the electric utility and industrial sectors. Environmental impacts of this increased coal and lignite use are projected in terms of increased air pollutant emissions and air quality impacts. Economic costs of compliance with alternative source emission regulations are also projected for the electric utility industry.Lignite consumption in Texas under the National Energy Plan is projected to increase from the present 13 million metric tons in 1976 to 57 million metric tons annually by 1985. Sub-bituminous coal consumption in Texas is projected to increase from 1 million metric per year in 1976 to 49 million metric tons per year in 1985. Bituminous coal consumption in Texas is expected to increase from less than one million metric tons per year in 1976 to about 3 million metric tons per year in 1985.Major increases in sulfur oxides emissions from coal and lignite combustion in Texas can be expected by 1985 of up to 1.5 × 10⁹ kg per year without controls and 0.2 × 10⁹ kg per year with controls. Increases in acid precipitation formation will result in north-east Texas from extensive lignite usage for electric power generation as a detriment to agriculture. The photochemical air pollution problem in the Houston area will probably worsen primarily because of increased nitrogen oxides and sulfur oxides emissions because of industrial coal combustion. Capital costs of air pollution controls in Texas for coal-fired utility boilers are estimated as up to U.S. $3.9 billion by 1985, with total operating costs of up to U.S. $1.2 billion per year.     

Dissipation of glyphosate and aminomethylphosphonic acid in water and sediment of two Canadian prairie wetlands

Glyphosate [N-(phosphonomethyl)glycine] is the active ingredient of several herbicide products first registered for use in 1974 under the tradename Roundup. The use of glyphosate-based herbicides has increased dramatically over the last two decades particularly in association with the adoption of glyphosate-tolerant crops. Glyphosate has been detected in a range of surface waters but this is the first study to monitor its fate in prairie wetlands situated in agricultural fields. An ephemeral wetland (E) and a semi-permanent wetland (SP) were each divided into halves using a polyvinyl curtain. One half of each wetland was fortified with glyphosate with the added mass simulating an accidental direct overspray. Glyphosate dissipated rapidly in the water column of the two prairie wetlands studied (DT₅₀ values of 1.3 and 4.8 d) which may effectively reduce the impact of exposure of aquatic biota to the herbicide. Degradation of glyphosate to its major metabolite aminomethylphosphonic acid (AMPA) and sorption of the herbicide to bottom sediment were more important pathways for the dissipation of glyphosate from the water column than movement of the herbicide with infiltrating water. Presently, we are not aware of any Canadian guidelines for glyphosate residues in sediment of aquatic ecosystems. Since a substantial portion of glyphosate entering prairie wetlands will become associated with bottom sediments, particularly in ephemeral wetlands, guidelines would need to be developed to assess the protection of organisms that spend all or part of their lifecycle in sediment.     

Nestmate recognition in three species of stenogastrine wasps (Hymenoptera,Vespidae)

The capacity to recognise a conspecific intruder was investigated in Parischnogaster jacobsoni, Liostenogaster flavolineata and L. vechti, three species of primitively social wasps of the subfamily Stenogastrinae. Results of behavioural experiments carried out in the field showed that females of all three species react pacifically if presented with female nestmates, but aggressively reject an intruder from a conspecific colony. As L. flavolineata and L. vechti both build large clusters of nests, often very close to each other, the recognition capacity among females from different nests, but in the same conspecific cluster, was also investigated. Females of both species were more aggressive towards females from a different colony in the same cluster than towards their female nestmates. Additional experiments on L. flavolineata showed that there was no difference in reaction towards females from colonies nearer or further from the tested colony but within the same cluster, nor towards females from a different cluster. The capacity to recognise an alien conspecific nest containing immature brood was investigated in P. jacobsoni. Adult females of this species, invited to land on an alien nest which had experimentally been exchanged for their own, accepted the new nest and partially destroyed the immature brood. The behaviour of the females when they land on an alien nest, however, suggests that they do recognise the nest as foreign. Acceptance of foreign nests coupled with low immature brood destruction is probably due to the high energetic costs of egg-deposition and larval rearing in stenogastrine wasps. These results suggest that nestmate recognition in these wasps is very efficient, even though they belong to the most primitive subfamily of social wasps. Received: 16 April 1996/Accepted after revision: 9 August 1996     

Importance of competition mechanisms in successive invasions by polyphagous tephritids in La Reunion

Understanding the strength and modes of interspecific interactions between introduced and resident species (native or previously introduced) is necessary to predict invasion success. We evaluated different mechanisms of interspecific competition among four species of polyphagous fruit flies (Diptera: Tephritidae) from the island of La Reunion: one endemic species, Ceratitis catoirii, and three exotic species, C. capitata, C. rosa, and Bactrocera zonata, that have successively invaded the island. Larval competition experiments, i.e., co-infestations of the same fruit, and behavioral interference experiments measuring the ability of one female to displace another from a fruit, were performed among all pairs of the four species. We observed asymmetric and hierarchical interactions among species in both larval and adult interference competition. In agreement with the hypothesis that invasion is competition-limited, the competitive hierarchy coincided with the temporal sequence of establishment on the island, i.e., each newly established species tended to be competitively dominant over previously established ones.     

Pigment composition and size distribution of phytoplankton in a confined Mediterranean salt marsh ecosystem

Pigment composition and size distribution of phytoplankton were analysed in a group of Mediterranean salt marshes, where hydrology is dominated by sudden inputs during sea storms, followed by long periods of confinement. These marshes are characterized by a low inorganic–organic nutrient ratio, and inorganic nitrogen is especially scarce due to denitrification. Nutrients were the main factor affecting phytoplankton biomass, while zooplankton grazing did not control either phytoplankton community composition, or their size distribution. The relative abundance of the different phytoplankton groups was analysed by correspondence analysis using the pigment composition measured by high-performance liquid chromatography (HPLC) and analysed with the CHEMTAX programme. In this analysis, phytoplankton pigment composition was correlated with two nutrient gradients. The first gradient was the ratio of nitrate–total nitrogen (TN), since the different phytoplankton groups were distributed according to their eco–physiological differences in nitrogen uptake. The second gradient was correlated with total nutrient loading. Biomass size distributions frequently showed a lack of intermediate sized nanophytoplankton (2.5–4 μm in diameter), and the importance of this lack of intermediate sizes correlated with dinoflagellate biomass. These results suggested that in confined environments, where nutrients are mainly in an organic form, dinoflagellates take advantage of their mixotrophy, by competing and grazing on smaller phytoplankters simultaneously.     

Développement larvaire de deux Tellinacea,Scrobicularia plana (Semelidae) et Donax vittatus (Donacidae)

Scrobicularia plana Da Costa and Donax vittatus L. were reared in the laboratory through settlement. Fertilizable eggs were obtained by perfusing the ovary with 5% 0.1 M ammonium hydroxyde in sea water. S. plana eggs have a thick chorion, inside which the early larval stages develop; they hatch as straight-hinge larvae more than 60 h after fertilization. This brood protection is considered to be an adaptation to osmotic pressure changes and pollution in the environment. D. vittatus eggs have a very thin chorion and are unprotected. Further development is planktotrophic and very similar for the two species. Under laboratory conditions, the pediveliger stage is attained 3 weeks after fertilization and settlement occurs 1 week thereafter. S. plana spat stop growing until a suitable substratum is available. Meanwhile they undergo a byssus drifting important for postlarval dispersion. Post larvae resume growth as soon as a small quantity of fine sand is added to the rearing jar. The exhalant siphon is developed first, when the post larvae reach a length of 600 m; the inhalant siphon is formed later, at a length of approximately 900 m. Evolution from the larval hinge to the juvenile hinge stage occurs sooner in S. plana than in D. vittatus. Comparison of laboratory larval development with field development indicates that spawning occurs in June and August for S. plana in North Wales (UK).