Nature-based tourism and the valuation of its environmental resources: Economic and other aspects

Nature-based tourism has grown in importance in recent decades, and strong links have been established between it and ecotourism. This reflects rising incomes, greater levels of educational attainment and changing values, especially in the Western world. Nature-based tourism is quite varied. Different types of such tourism are identified and their consequences for sustainability of their resource-base are briefly considered. The development and management of nature-based tourism involves many economic aspects, several of which are discussed. For example, one must consider the economics of reserving or protecting land for this type of tourism. What economic factors should be taken into account? Economists stress the importance of taking into account the opportunity costs involved in such a decision. This concept is explained. However, determining the net economic value of an area used for tourism is not straightforward. Techniques for doing this, such as the travel cost method and stated value methods, are introduced. Natural areas reserved for tourism may have economic value not only for tourism but also jointly for other purposes, such as conserving wildlife, maintaining hydrological cycles and so on. These other purposes, should be taken into account when considering the use of land for nature-based tourism. According to one economic point of view, land should be used in a way that maximises its total economic value. While this approach has its merits, it does not take into account the distribution of benefits from land use and its local impacts on income and employment. These can be quite important politically and for nature conservation, and are discussed. Finally, there is some discussion of whether fees charged to tourists for access to environmental resources should discriminate between domestic tourists and foreigners.

Antarctic tourists: A case study of their evaluation of Antarctic wildlife and environmental issues

Reports the results of surveys of Antarctic cruise ship passengers on the ‘Akademik Ioffe’ who undertook their Antarctic journey in January 2003. The prime purposes of the surveys were to determine the socio-economic profile of these travellers, evaluate the importance of Antarctic wildlife for their travel, their attitude to Antarctic wildlife conservation as well as environmental issues involving Antarctica, both prior to their tourist visit to Antarctica and following it. This paper reports on the socio-economic profile of respondents, their willingness to pay for their Antarctic trip, and their knowledge of Antarctica. The comparative importance of Antarctic wildlife as a factor motivating respondents to undertake their journey is assessed and the evaluation of travellers following their Antarctic visit is considered. The relative importance of different Antarctic wildlife species is taken into account as well as Antarctic attractions other than wildlife. The attitudes of respondents to several environmental issues involving Antarctica, (eg. the commercial use of its natural resources and global environmental change impacting on Antarctica) are canvassed and summarised. In conclusion, the relevance of the survey results for Antarctic conservation are discussed. Particular attention is given to the question of whether Antarctic tourism favours or threatens Antarctic nature conservation.

Economics of Environmental Conservation

This fully updated and comprehensively revised edition of a classic text concentrates on the economics of conserving the living environment. It begins by covering the ethical foundations and basic economic paradigms’ essential for understanding and assessing ecological economics. General strategies for global environmental conservation, policies for government intervention, developing countries, preserving wildlife and biodiversity, open-access to and common property in natural resources, conservation of natural areas, forestry, agriculture and the environment, tourism, sustainable development and demographic change are also all covered.

Regulation of photosynthetic pigments in micro-algae by multiple environmental factors: a dynamic balance hypothesis

Environmental effects on the concentration of photosynthetic pigments in micro-algae can be explained by dynamics of photosystem synthesis and deactivation. A model that couples photosystem losses to the relative cellular rates of energy harvesting (light absorption) and assimilation predicts optimal concentrations of light-harvesting pigments and balanced energy flow under environmental conditions that affect light availability and metabolic rates. Effects of light intensity, nutrient supply and temperature on growth rate and pigment levels were similar to general patterns observed across diverse micro-algal taxa. Results imply that dynamic behaviour associated with photophysical stress, and independent of gene regulation, might constitute one mechanism for photo-acclimation of photosynthesis.

Relationship between peptide selectivities of human transporters associated with antigen processing and HLA class I molecules

Efficiency of presentation of a peptide epitope by a MHC class I molecule depends on two parameters: its binding to the MHC molecule and its generation by intracellular Ag processing. In contrast to the former parameter, the mechanisms underlying peptide selection in Ag processing are poorly understood. Peptide translocation by the TAP transporter is required for presentation of most epitopes and may modulate peptide supply to MHC class I molecules. To study the role of human TAP for peptide presentation by individual HLA class I molecules, we generated artificial neural networks capable of predicting the affinity of TAP for random sequence 9-mer peptides. Using neural network-based predictions of TAP affinity, we found that peptides eluted from three different HLA class I molecules had higher TAP affinities than control peptides with equal binding affinities for the same HLA class I molecules, suggesting that human TAP may contribute to epitope selection. In simulated TAP binding experiments with 408 HLA class I binding peptides, HLA class I molecules differed significantly with respect to TAP affinities of their ligands, As a result, some class I molecules, especially HLA-B27, may be particularly efficient in presentation of cytosolic peptides with low concentrations, while most class I molecules may predominantly present abundant cytosolic peptides.

Hypothalamic dopamine D1 receptors are involved in the stimulation of prolactin secretion by high environmental temperature in the female sheep

Recent evidence suggests that dopamine, acting via its D1 receptors, may function as a neurotransmitter in intrahypothalamic pathways involved in the stimulation of prolactin secretion. Functional dopamine D1 receptors are present in the ventromedial hypothalamic nucleus (VMH) and we hypothesized that they might be part of a prolactin-stimulatory pathway activated by stress. We tested this hypothesis in a series of experiments on sheep involving two different forms of stressors, audiovisual (barking dog) and high environmental temperature. We attempted to block the stimulation of prolactin secretion by infusion into the VMH of an antagonist specific for the D1 receptor. Ovariectomised, oestradiol-implanted merino ewes were surgically implanted with bilateral guide tubes directed at the VMH. After a 180 min pretreatment period, the ewes either were or were not exposed to a stressor (30 min of barking dog or 120 min at 35 degrees C, 65% relative humidity). D1 receptor antagonist, SCH23390 or vehicle (0.9% saline) was infused into the VMH (1.7 mu l/h, 120 nmol/h) for 60 min prior to and during the stressor period. Blood was sampled every 15 min via jugular cannulae and the plasma was assayed for prolactin, cortisol and growth hormone (GH). Both stressors significantly increased prolactin concentrations over control levels. SCH23390 infusion significantly attenuated the prolactin response to high environmental temperature, but had no effect on the prolactin response to audiovisual stress. Cortisol concentrations were significantly increased by audiovisual stress only and were not affected by SCH23390, GH concentrations were not changed by either stressor or infusion. Drug infusion alone did not affect the concentration of the hormones. The data suggest that the VMH D1 receptors are involved in a prolactin stimulatory pathway in response to high environmental temperature. The inability of the D1 antagonist to affect the response to the barking dog indicates that this pathway is stress-specific, implying that there is more than one mechanism or pathway involved in the prolactin response to different stressors.

Split tolerance to a viral antigen expressed in thymic epithelium and keratinocytes

When expressed as a transgene from the keratin 14 (K14) promoter in an MHC class II-deficient mouse, I-Ab expressed in thymic cortical epithelium promotes positive but not negative selection of I-Ab-restricted CD4(+) T cells (Laufer, T. M. et al., Nature 1996. 383:81-85). Transgenic mice expressing the E7 protein of human papilloma virus 16 from the K14 promoter were studied to determine the consequence of expression of a cytoplasmic/nuclear protein from the K14 promoter. K14E7-transgenic mice express E7 in the thymus and skin without evidence for autoimmunity to E7. Repeated immunization of FVB(H-2(q)) or F1(C57BV6JxFVB) mice with E7 elicited similar antibody responses to the defined B cell epitopes of E7 in K14E7-transgenic and non-transgenic animals. In contrast, for each genetic background, a single immunization with E7 elicited demonstrable T cell proliferative responses to the major promiscuous T helper epitope of E7 in the transgenic but not the non-transgenic animals. Further,E7-immunized non-transgenic F1 (FVBxC57BL/6J) animals developed strong E7-specific cytotoxic T lymphocyte (CTL) responses and were protected against challenge with E7(+) tumors, whereas similarly immunized K14E7-transgenic animals had a markedly reduced CTL response to E7 and no E7-specific tumor protection was observed, although the antibody and CTL response to ovalbumin was normal. Expression of E7 protein as a transgene from the K14 promoter in the skin and thymus thus induces E7-specific tolerance in the cytotoxic T effector repertoire, together with expansion of the E7-specific T helper repertoire. These findings demonstrate that limited tissue distribution of an autoantigen may result in split tolerance to that autoantigen.

Environmental poisoning: Presentation and management

Environmental poisoning is most commonly associated with chronic longterm exposure to toxins rather than to acute exposure. Such repeated exposure to sublethal doses of compounds and elements presents problems in risk assessment. This is primarily because the data are unavailable to describe relationships between dose and effect at lower levels of exposure to toxins. Bioavailability of toxins also presents a problem because the data on bioavailability are sparse and seldom as high as the default of 100% bioavailability commonly used in risk assessment. Examples are presented of two toxins: arsenic as an elemental anthropogenic and geologic poison and ciguatoxin, a polyether ladder compound, as a toxin produced naturally by dinoflagellates. Bioavailability drives the toxicity of arsenic from contaminated sites, whereas tissue accumulation drives the toxicity of ciguatoxin. Considerable benefit is derived from the harmonization of regulatory processes where there is linkage of health and environmental factors in the derivation of credible risk assessment.

A framework for selecting appropriate remotely sensed data dimensions for environmental monitoring and management

Two major factors are likely to impact the utilisation of remotely sensed data in the near future: (1)an increase in the number and availability of commercial and non-commercial image data sets with a range of spatial, spectral and temporal dimensions, and (2) increased access to image display and analysis software through GIS. A framework was developed to provide an objective approach to selecting remotely sensed data sets for specific environmental monitoring problems. Preliminary applications of the framework have provided successful approaches for monitoring disturbed and restored wetlands in southern California.

Insufficiently active Australian college students: Perceived personal, social, and environmental influences

Background. A sustainable pattern of participation in physical activity is important in the maintenance of health and prevention of disease, College students are in transition from an active youth to a more sedentary adult behavior pattern. Methods. We assessed self-reported physical activity and other characteristics in a sample of 2,729 male and female students (median age was 20 years) recruited from representative courses and year levels at four Australian College campuses. They were categorized as sufficiently or insufficiently active, using estimates of energy expenditure (kcal/week) derived from self-reported physical activity, Personal factors (self-efficacy, job status, enjoyment), social factors (social support from family/friends), and environmental factors (awareness of facilities, gym membership) were also assessed. Results. Forty-seven percent of females and 32% of males were insufficiently active. For females, the significant independent predictors of being insufficiently active were lower social support from family and friends, lower enjoyment of activity, and not working. For males, predictors were lower social support from family and friends, lower enjoyment of activity, and being older. Conclusions. Factors associated with physical activity participation (particularly social support from family and friends) can inform physical activity strategies directed at young adults in the college setting. (C) 1999 American Health Foundation and Academic Press.