Equity impacts of proposals for federal product charges

Pollution taxes have been studied as instruments for promoting environmental objectives in an efficient manner. Their adoption has also been recommended, although less rigorously, on equity grounds. In the case of solid wastes it has been contended that persons whose waste generation occasions local public outlays for refuse service should pay commensurately, but that they often do not under general revenue financing. How proposals for federal product charges might reduce current inequities, so conceived, is the subject of the paper. The behavioral responses of local public officials to federal grants funded by charge revenues and the design of the grant formula are identified as potentially important factors in that regard.     

Classification and ordination of benthic samples from Bedeque Bay,an estuary in Prince Edward Island,Canada

An attempt was made to identify the causes of the distribution of benthos within Bedeque Bay using multivariate techniques programmed for the computer. Both classification by a hierarchical cluster analysis, and ordination by principal components analysis suggested that a large proportion of the variance in the data was directly or indirectly correlated with a salinity gradient. Classification divided the species into two main groups, a in the upper half of the estuary where lower salinities and larger salinity fluctuations occurred, and group b in the lower half of the estuary with a more stable salinity regime. The group b species were further subdivided into those preferring soft mud and those preferring sandier sediments. The group a species were divided into a well-developed oyster association and various sub-groups less strongly associated with oysters. Five principal components were required to account for 50% of the variance in the data. The first axis accounted for 20% of the variance and was shown by a non-parametric test to be correlated with the salinity gradient. Axes II to V could not be interpreted, but possibly represented complex species interactions. By providing hard substrates and altering the natura of the sediment, oysters and mussels produced conditions suitable for many other species.     

Zinc phosphate granules in tissue surrounding the midgut of the barnacle Balanus balanoides

The chemical composition of inorganic granules found in parenchyma cells surrounding the midgut of adult Balanus balanoides (L.) was determined. X-ray microanalysis indicated the presence of magnesium, phosphorus, potassium, calcium, iron and zinc in the granules. A quantitative analysis of granule-rich pellets isolated from the midguts of adult barnacles showed that the granules were composed mainly of zinc phosphate, the remaining elements being minor constituents only.     

Role of glutamine synthetase in ammonia assimilation by symbiotic marine dinoflagellates (zooxanthellae)

The dinoflagellate symbionts (zooxanthellae) present in many reef corals aid in the survival of the symbiotic unit in nitrogen deficient tropical waters by providing additional routes of nitrogen uptake and metabolism. The enzymatic pathway of ammonia assimilation from seawater and the re-assimilation of coral ammonium waste by zooxanthellae was studied by examining the affinity of glutamine synthetase for one of its substrates, ammonia. Glutamine synthetase activity was measured in dinoflagellates of the species Symbiodinium microadriaticum found in symbiotic association with various marine coelenterates. Michaelis-Menten kinetics for the substrate ammonia were determined for freshly isolated dinoflagellates from Condylactis gigantea (apparent NH₃ K_m=33 M) and for cultured dinoflagellates from Zoanthus sociatus (apparent NH₃ K_m=60 M). On the basis of the low apparent K_ms for NH₃, it appears that ammonia assimilation by these symbiotic dinoflagellates occurs via the glutamine synthetase/glutamate synthase pathway. Additionally, the uptake of exogenous ammonium by an intact coelenterate-dinoflagellate symbiosis was strongly inhibited by 0.5 mM methionine sulfoximine, and inhibitor of glutamine synthetase.     

Territory dynamics in a sage sparrow population: are shifts in site use adaptive?

Summary In 1981–1985, we studied territory dynamics in a southeastern Idaho sage sparrow population to evaluate the hypothesis that territory shifts represent adaptive adjustments in site use. We predicted that shifts should (1) result in changes in territory characteristics, (2) be influenced by previous reproductive success and result in greater success, and (3) decline in magnitude for individual males over time. Habitat features of territories changed little as a result of shifts, but territory size increased. Correspondingly, habitat features of territories were unrelated to reproductive success, whereas territory size was positively related. The magnitude of territory shifts was negatively correlated with preshift fledging success, and after shifts, males experienced greater average reproductive success than before. Successive territory shifts by individual males became progressively smaller. Thus, territory shifting by sage sparrows seems to be adaptive behavior aimed primarily at increasing territory size.     

Chemical ornaments of male lizards <Emphasis Type="Italic">Psammodromus algirus</Emphasis> may reveal their parasite load and health state to females

Evidence for parasite-mediated sexual selection has been found in many species that use visual ornaments to attract females. However, in many animals, variation in female responses to scents of parasitized males suggests that parasitic infections might also affect information conveyed by pheromones (i.e., chemical ornaments). Thus, pheromones might also function in parasite-mediated sexual selection. We show here that female lizards Psammodromus algirus responded differently to femoral gland secretions of males according to the parasite load and health of these males. Scents of healthier males elicited more tongue flicks (a chemosensory behavior) by females, suggesting that these scents were more attractive. Chemical analyses showed that parasite load and the T-cell-mediated immune response were related to the variability in the proportions of some lipids in secretions of males. Further trials testing the chemosensory responses of females to chemical standards indicated that females actually discriminated the chemicals related to males’ health from other chemicals found in secretions. We suggest that these chemical ornaments may provide reliable information on the health and degree of parasitic infection of a male.     

Large nonlethal effects of an invasive invertebrate predator on zooplankton population growth rate

We conducted a study to determine the contribution of lethal and nonlethal effects to a predator's net effect on a prey's population growth rate in a natural setting. We focused on the effects of an invasive invertebrate predator, Bythotrephes longimanus, on zooplankton prey populations in Lakes Michigan and Erie. Field data taken at multiple dates and locations in both systems indicated that the prey species Daphnia mendotae, Daphnia retrocurva, and Bosmina longirostris inhabited deeper portions of the water column as Bythotrephes biomass increased, possibly as an avoidance response to predation. This induced migration reduces predation risk but also can reduce birth rate due to exposure to cooler temperatures. We estimated the nonlethal (i.e., resulting from reduced birth rate) and lethal (i.e., consumptive) effects of Bythotrephes on D. mendotae and Bosmina longirostris. These estimates used diel field survey data of the vertical gradient of zooplankton prey density, Bythotrephes density, light intensity, and temperature with growth and predation rate models derived from laboratory studies. Results indicate that nonlethal effects played a substantial role in the net effect of Bythotrephes on several prey population growth rates in the field, with nonlethal effects on the same order of magnitude as or greater (up to 10-fold) than lethal effects. Our results further indicate that invasive species can have strong nonlethal, behaviorally based effects, despite short evolutionary coexistence with prey species.     

Effects of Historic Livestock Grazing on Vegetation at Chaco Culture National Historic Park, New Mexico

Abstract:   Livestock grazing is the most ubiquitous land use in western North America, yet it rarely has been studied in a controlled manner because of the lack of large areas free of grazing. We compared the ecological effects of three grazing treatments—long-term protection, short-term protection, and currently grazed—at Chaco Culture National Historic Park in northern New Mexico. Chaco has a long history of human habitation and is now one of the largest grazing exclosures in the American West. We studied the effects of livestock grazing on the cover of plants, soil crusts, and plant species richness at six sites with different potential natural vegetation. Species richness was higher under long-term protection than under current grazing at all six sites. Trends in shrub and grass response varied significantly across the six sites. Shrub cover increased with long-term protection at four upland sites, and grass cover increased with protection at four sites. The response of Chaco vegetation to release from grazing varied significantly according to each site's ecological potential, determined in part by edaphic and topographic characteristics. These nuances in vegetation response represent natural ecological variation and contrast with the notions of widespread shrub "invasion" often inferred in the past.