The empirical properties of two classes of designs for transferable discharge permit markets

Previous work by Atkinson and Lewis (J. Environ. Econ. Manag.1, 237–250 (1974)) and Anderson et al. (“An Analysis of Alternative Policies for Attaining and Maintaining a Short-Term NO₂ Standard,” MATHTECH, Inc., Princeton, N.J., 1979) has indicated the tremendous cost advantages to be achieved by moving from a policy based on emission standards to one based on marketable emission permits. As Tietenberg (Land Econ.56, 391–416 (1980)) points out, however, neither of the major permit designs treated in the literature are optimal from all points of view. This has triggered a search for alternative permit designs, which, while they may not minimize compliance costs, have sufficient other virtues as to make them attractive on other grounds. The purpose of this paper is to examine, within the context of an empirical mathematical programming model, the air quality, emission, and cost consequences of two classes of the permit designs which can be implemented in the absence of information on control costs. This case study involves particulate control in St. Louis.     

Light harvesting by wavelength transformation in a symbiotic coral of the Red Sea twilight zone

We report an extraordinary depth range for Leptoseris fragilis (Milne Edwards and Haime), a reef building coral of the Red Sea living in cytosymbiosis with zooxanthellae. The coral harbours an as yet unknown pigment system. We suggest that the heterotrophic host — the coral — provides its photoautotrophic symbionts with additional light. The supplementary light is provided by host pigments which transform light of short wavelengths into suitable wavelengths for photosynthesis, thus amplifying and increasing the transfer of photoassimilates from the zooxanthellae to the host.     

Effects of Ecotourism on Distribution of Waterbirds in a Wildlife Refuge

Humans visiting natural areas often disturb wildlife, possibly displacing animals from desirable habitat. To hold ecotourism at acceptable levels refuge managers need to know which species are likely to be affected and which response occurs at different levels of disturbance. Displacement of waterbirds at J. N. "Ding" Darling National Wildlife Refuge, Florida (U.S.A.), by specific human activities was demonstrated experimentally by Klein in 1993. We assessed the extent of this effect of ecotourism on the distribution of 38 species of waterbirds by surveying birds in plots of known distance from a dike along which wildlife tours occurred. Most resident species were less sensitive to disturbance than were migrants. Migrant ducks were most sensitive when they first arrived, mid-October to mid-December, usually remaining more than 80 m from the drive, even at low levels of human visitation. Herons, egrets. Brown Pelicans ( Pelecanus occidentalis ), and Anhingas ( Anhinga anhinga ) were most likely to remain close to areas of high human activity. Shorebirds were displaced at intermediate distance and visitation levels. Mottled Ducks ( Anas fulvigula ) and several of the ardeids seemed to include two groups differing in behavior, one habituated to humans and one sensitive to disturbance. Public education and changes in management practices are needed to reduce disturbance. Guided tours and low-disturbance zones where people stay in their cars could reduce the negative effects of tourists, especially in the fall when migrants arrive. The number of human visitors may have to be reduced or the wildlife drive closed on certain days during the tourist season.     

The effects of nesting stage,sex, and type of predator on parental defense by killdeer (Charadrius vociferous): testing models of avian parental defense

Summary Two models predicting the temporal patterns of parental investment in offspring defense over the nesting cycle were tested. The first is based on offspring age, the other on the vulnerability of offspring to predation. Both models make very similar predictions for altricial species after eggs have hatched, i.e., increases in intensity of parental defense until fledging. For precocial species, however, the post-hatching predictions of each model are different: the offspring age model predicts a continued increase in defense intensity, while the vulnerability model predicts a decline. I examined the temporal patterns of parental defense of a precocial shorebird, the killdeer (Charadrius vociferus), and determined which model was supported. Killdeer responses to human and natural predators were observed. Killdeer were less willing to leave the nest, responded most intensely, and displayed closest to a potential predator around hatching. Defense intensity increased from early to late incubation as predicted by the offspring age model. However, after hatching killdeer parental defense declined for both males and females, thus supporting the vulnerability model for this stage. Males and females responded significantly differently to all types of predators. Males took greater risks, remained on the nest longer, defended offspring more intensely, and displayed closer to the predator than females at the approach of a potential predator. Responses to natural predators depended on the type of predator and the approach made by the predator; a greater range of defense behavior was used for predators approaching on the ground compared to aerial predators. In general, killdeer responses to humans were more intense and less variable than their responses to natural predators. This was most likely because the human intruder approached nests and chicks more directly and closer than natural predators.     

Venoms from six species of marine fish: lethal and hemolytic activities and their neutralization by commercial stonefish antivenom

A specimen of the stonefish Synanceja verrucosa was captured in Okinawa in March 1988. Live specimens of the scorpionfish Inimicus japonicus were purchased from the Tokyo Central Wholesale Market in November 1988 and those of four species of zebrafish Pterois lumulata, P. volitans, P. antennata and Dendrochirus zebra from an aquarium in December 1988. Crude venoms were extracted from dorsal spines of the six species. All venoms exhibited lethal activity against mice and hemolytic activity specific for rabbit erythrocytes. The lethal activity (or hemolytic activity) of each venom was very unstable to freezing, lyophilization and heating. Both lethal and hemolytic activities of S. verrucosa venom were remarkably neutralized by the commerical stonefish (Synanceja trachynis) antivenom. This antivenom was also effective, to some extent, in counteracting the other venom activities. The neutralizing capacities of the antivenom were calculated to be 7310 LD₅₀ ml^-1 for S. verrucosa venom and 1 220 to 2 990 LD₅₀ ml^-1 for the other venoms. Results of neutralization tests suggest that venoms from the six species were comparable in terms of antigenecity.     

Gill pump characteristics of the soft clamMya arenaria

Pumping rates in the soft clamMya arenaria, collected in June 1987 in the Great Belt, Denmark, were determined as rates at which clams cleared suspensions of algae,Dunaliella marina. The frictional resistance of the siphons to water flow was estimated by studying the effect of excision of the siphons at the base on the rate of water pumping. The frictional resistance was also calculated from the Poiseuille equation. Excision of the siphons had no measurable effect on the pumping rate, and calculations indicated pressure losses ranging between 0.3 to 1.2 mm H₂O. This is consistent with the conception that the capacity of filter feeding bivalves to process large amounts of water depends upon a low resistance to water flow in the siphons.     

Is there a “sound window” for primate communication?

Summary It has long been asserted that habitat acoustics can determine the frequency band bestadapted for long-range communication, but the generality and validity of measurements claiming to demonstrate a window of best frequencies have recently been questioned. We report the discovery of a prominent sound window in Kenyan rain forest in a study that is free of methodological difficulties. Our results allow us to calculate the range advantage attained by an animal vocalizing within the sound window, and show that sound windows can be a potent factor for the evolution of primate communication.