Trophic upgrading of food quality by protozoans enhancing copepod growth: role of essential lipids

 Protozoa are known for their intermediary trophic role in transferring organic matter from small size planktonic particles to mesozooplankton. This study concentrates on the possible addition of biochemical value during this transfer, by new production of compounds that are essential in copepod food. In laboratory experiments, copepods could not be raised on a diet of the chlorophycean Dunaliella sp., though they readily consumed this alga. Dunaliella sp. contained all essential amino acids, but was deficient in highly unsaturated fatty acids and in sterols. In contrast to copepods, the heterotrophic dinoflagellate Oxyrrhis marina grew well on Dunaliella sp., producing significant amounts of the long-chain fatty acids docosahexaenoic acid and eicosapentaenoic acid, in addition to cholesterol and brassicasterol. Using this O. marina grown on Dunaliella sp. to feed Temora longicornis and Pseudocalanus elongatus, both copepod species rapidly developed from young nauplius larvae to maturity on the dinoflagellate diet. Hence, in this experimental food-chain the inadequate chlorophycean food was biochemically upgraded by the protozoan to high-quality copepod food. The results indicate that highly unsaturated fatty acids and/or sterols are essential compounds, which can be produced by protozoans. Due to their intermediate size, the mechanism of trophic upgrading by protozoans may bridge the gap of essential nutrients between the microbial loop and higher trophic levels. Received: 11 January 1999 / Accepted: 3 June 1999     

Cleaner production and industrial ecosystems, a Dutch experience

This article opens briefly with the recent discussions about the effectiveness of pollution prevention. As pollution prevention and cleaner production are important elements of industrial ecology, the different definitions and approaches of industrial ecology as a term also need clarity. The major part of this article reflects the first results of the cleaner production and industrial ecology concepts, applied in an industrial ecosystem project (INES) in the Rotterdam harbour area. In this industrial area with many refineries and (petro)chemical facilities, the possibilities for companies to reuse waste streams, by-products and energy from each other was researched. The project was initiated by an industrial association. Sixty-nine members of the industrial association joined the INES project and provided confidential information about their resources, products and waste streams to the research team. Based on this information, 15 projects were designed. The selected three projects for further feasibility studies showed the potency to reduce the use of energy, water and bio sludge significantly.     

关于清洁生产术语学的思考

政府和工业界现在普遍偏爱以清洁生产为代表的预防性思路.然而,新概念和新术语往往造成混淆.本文意在帮助解这个"纠缠在一起的术语之网".     

Influence of ethnicity on recreation and natural environment use patterns: Managing recreation sites for ethnic and racial diversity

Management of natural environment sites is becoming increasingly complex because of the influx of urbanized society into wildland areas. This worldwide phenomenon impacts a wide range of countries. In southern California ethnicity is often a major factor influencing recreation site use and behavior at sites in the wildland-urban interface. This study investigated the role of ethnicity and race on the use patterns, perception of environment, and recreation behaviors at an outdoor recreation site visited by an ethnically diverse population. Two research questions were asked: (1) What ethnic groups engage in outdoor recreation at this site, and (2) what differences can be assigned to these various groups? Data were collected from 250 recreationists during 1991. Three major ethnic groups were identified, and statistically significant differences were found in the importance of site attributes, activity participation, and in preferred and actual communication channels. Management implications and strategies based on group differences are discussed.     

Critical success and limiting factors for eco-industrial parks: global trends and Egyptian context

The trend of clustering industries into regional estates or cities was adopted in the mid 1900’s. At present, the number of industrial estates in the world is estimated to be between 12,000 and 20,000 (UNEP, 1997) and this trend is continuing to rise in both developed and developing countries. The implementation of the EIP concept continues to evolve especially with the environmental threats and impact on climate change that industries pose. However, there is not yet a fully developed EIP that is operating; although some successful examples of regional by-product exchanges are functioning ( [Lowe, 2001], [Peck, 2002], [Lowe et?al., 1995] and [Chertow, 2000]). Actually, a significant number of projects have failed or have abandoned the goal of becoming an EIP. Furthermore the current body of knowledge on industrial ecology is not sufficient to provide practical solutions to the obstacles facing EIPs.This paper is based upon the Ph.D. Doctoral thesis research of D. Sakr. It was prepared to examine means to improve the uptake of cleaner production & industrial symbiosis in industrial areas in Middle East & North Africa Region focusing on Egypt as a case study. An extensive literature review was performed on eco-industrial development projects’ experiences around the world, in order to identify the critical driving and limiting factors for EIPs. This paper summarizes the lessons learned from worldwide EIP experiences as a basis for the planning and implementation of future EIPs. The paper reflects as well upon the Egyptian context for the identified EIP success and limiting factors. The identified key success and limiting factors are: the creation of symbiotic relationship, information sharing and awareness, financial benefits, organizational structure, and legal and regulatory framework.     

Estimation of no effect concentrations from exposure experiments when values scatter among individuals

The parameters that are most commonly used in risk assessment, LC_x values or no observed effect concentrations, both have serious drawbacks. As an alternative, No effect concentrations (NEC) as a parameter in a process-based model, offer great potential in risk assessment.     

Model-based experimental design for assessing effects of mixtures of chemicals

We exposed flour beetles (Tribolium castaneum) to a mixture of four poly aromatic hydrocarbons (PAHs). The experimental setup was chosen such that the emphasis was on assessing partial effects. We interpreted the effects of the mixture by a process-based model, with a threshold concentration for effects on survival. The behavior of the threshold concentration was one of the key features of this research. We showed that the threshold concentration is shared by toxicants with the same mode of action, which gives a mechanistic explanation for the observation that toxic effects in mixtures may occur in concentration ranges where the individual components do not show effects. Our approach gives reliable predictions of partial effects on survival and allows for a reduction of experimental effort in assessing effects of mixtures, extrapolations to other mixtures, other points in time, or in a wider perspective to other organisms.