Environmental Radioactivity and Volcanological Features of Three Islands of the Mediterranean Sea (Pantelleria, Ustica and Vulcano)

The Mediterranean Sea is an area of great interest for its volcanic activities. This paper presents a comparative study of radiometric and chemical data regarding three volcanic islands located in southern Italy (Pantellena, Ustica, and Vulcano) characterized by different magmatic histories. Measurements of radionulide contents and chemical composition of rock samples belonging to the main lithologies present in the three islands were carried out the observed correlations among radiometric, chemical and mineralogical data reflect the differences in the volcanological genesis and suggest some hypotheses on the magmatic evolution.     

Developing a Criterion for Delisting the Southern Sea Otter under the U.S. Endangered Species Act

Recent surveys of recovery plans indicate that criteria, such as population sizes, for delisting species from the U.S. Endangered Species Act (ESA) are often unrealistically low by scientific standards. We describe the delisting criterion for the threatened southern sea otter (Enhydra lutris nereis) developed by the Southern Sea Otter Recovery Team. A major oil spill is the most serious threat to this sea otter population. After extensive modeling of oil spills, the recovery team concluded that it was not scientifically defensible to develop a delisting criterion in terms of a single probability of extinction over a specified time period. Instead, the team decided to define a size at which it would consider the population endangered and to consider the population threatened as long as a major oil spill might reduce it to that size. The effective population size (N_e) for endangered status was set at 500, estimated to be about 1850 otters. Using a spill the size of the Exxon Valdez spill (250,000 bbl), the oil spill model was iterated to generate a frequency distribution of the number of sea otters contacted by oil, from which the team estimated that less than 800 otters would be killed by 90% of the simulated spills. Thus, the delisting criterion was set at 1850 + 800 = 2650 individuals. There have been several proposals to improve the Endangered Species Act by providing quantitative guidance, in the form of specific probabilities of extinction within some time frame or specific criteria like those used by the World Conservation Union as to the levels of extinction risk represented by the terms "threatened" and "endangered." Experiences of the Sea Otter Recovery Team indicate that guidelines should not be overly rigid and should allow flexibility for dealing with specific situations. The most important consideration is to appoint a recovery team that is both technically well qualified and unconstrained by pressures from management agencies.     

Permanent exposure versus facultative concealment of sexual traits: an experimental study in the house sparrow

In many bird species the cryptic winter plumage is due to the presence of light feather tips that conceal conspicuous colorations. The gradual abrasion of these tips that makes sexual traits visible has been interpreted as a strategy to improve mating success (here referred as the permanent exhibition hypothesis). However, under some circumstances, the maintenance of a full plumage that facultatively enables the bird to exhibit or cover aggression-inducing traits has proved to be advantageous (the coverable badge hypothesis). In a population of house sparrows where black throat patches (here called badges) are used in intrasexual competition, the degree of abrasion of dull feather tips that conceal bright colour early in the breeding season correlated neither with badge size nor with traits indicating morphology and body condition. These results are only in accordance with predictions of the coverable badge hypothesis. In 1992 experimental clipping of badge feather tips, which forced permanent exposure of badges, negatively affected birds with the largest badges in terms of nest acquisition, but an opposite trend was indicated for birds with the smallest badges. In 1993, when more novel birds in the study area were competing for nesting sites than in 1992, only badge size, but not the experimental manipulation, affected nesting success. These results suggest that the loss of the ability to conceal badges was disadvantageous, and more so if most competing individuals had already been resident in the colony in previous years and the larger their badges were. There is a striking contrast between the results reported for this study population, where badges mainly signal fighting ability, and those reported for another house sparrow population, where badges are mainly used in mate choice. In this last population, tip abrasion is advantageous for dominant individuals showing the largest badges. This suggests that the trade-off between conserving versus wearing off the feathers that conceal ornaments could have different optimal resolutions depending on the relative importance of inter and intrasexual selection on indicator traits. Received: 29 September 1995/Accepted after revision: 14 July 1996     

A process for selecting indicators for monitoring conditions of rangeland health

This paper reports on a process for selecting a suite of indicators that, in combination, can be useful in assessing the ecological conditions of rangelands. Conceptual models that depict the structural and functional properties of ecological processes were used to show the linkages between ecological components and their importance in assessing the status and trends of ecological resources on a regional scale. Selection criteria were developed so that relationships could be assessed at different spatial scales using ground and aerial measurements. Parameters including responsiveness and sensitivity to change, quality assurance and control, temporal and spatial variability, cost-effectiveness and statistical design played an important role in determining how indicators were selected. A total of ten indicator categories were selected by a committee of scientists for evaluation in the program. A subset that included soil properties, vegetation composition and abundance, and spectral properties was selected for evaluation in a pilot test conducted in 1992 in the Colorado Plateau region of the southwestern United States. This work is part of a major effort being undertaken by the U.S. Environmental Protection Agency and its collaborators to assess the condition of rangelands (primarily comprised of arid, semi-arid and dry subhumid ecosystems) along with seven other ecosystem groups (forests, agricultural lands, wetlands, surface waters, landscapes, estuaries and Great Lakes) as part of a national Environmental Monitoring and Assessment Program (EMAP). The indicator selection process reported upon was developed to support EMAP's goal of providing long-term, policy-relevant research focusing on evaluating the ecological condition (or health) of regional and national resources.     

Contaminants in Muscle of Plaice and Halibut Collected From the St. Lawrence Estuary and Northwest Atlantic

Levels of aromatic hydrocarbons in muscle or plaice and halibut were determined by fluorescence, using the chrysene standard, as recommended by the International Oceanographic Commision, for the analysis of PAH in environmental extracts. Concentrations were highest in muscle of halibut collected at the most contaminated, nearshore site, in the Saguenay Fjord of the St. Lawrence Estuary, compared to other locations further from shore. Although concentrations of fluorescing compounds were not statistically different in plaice, the saturated hydrocarbons displayed unquestionably more biodegradation, with a decrease of n-alkanes and increase of branched aliphatics, at the less contaminated site. Synchronous fluorescence indicated the presence of benzenoid and biphenyl hydrocarbons in the extracted mixtures, while GC-MS-TIC analysis tentatively identified the presence of a series of benzenoid (alkyl benzenes), chlorinated (PCB and DDE), N (trialkylamines) and O (phenols) hydrocarbons. These anthropogenic compounds could derive from petroleum products, surfactants and common products used in industry and households. This study emphasizes the importance of a multispectroscopic approach when investigating complex environmental mixtures.     

Genetic and evolutionary constraints for the symbiosis between animals and methanogenic bacteria

It has been assumed that the feeding habits of animals predispose the composition of the microbial biota living in their intestinal tracts. Here we show that in arthropods and vertebrates the presence of methanogenic bacteria requires a quality of the host that is under phylogenetic rather than dietary constraint: competence for intestinal methanogenic bacteria is a primitive-shared character among reptiles, birds, and mammals, and a shared-derived trait of millipedes, termites, cockroaches and scarab beetles. The presence of methanogenic bacteria seems to be a prerequisite for the evolution of anatomic specializations of the intestinal tract such as hindguts, caeca or rumina, and it is likely that it also has consequences for the reproductive strategies of the animals.Methanogenic animals contribute to atmospheric methane by their breath and faeces. Because the status as either methane-producer or non-producer is shared by most species belonging to a higher taxonomic unit, it is possible to calculate methane emissions that are characteristic for whole taxa. In combination with ecological field data on the biomass it is possible to arive at estimates concerning the global contributions by animals.The demonstration of a genetic basis for the symbiosis between methanogens and animals will allow new approaches for the reduction of methane emission by domestic animals.     

Dissipation of Tidal Energy and Associated Mixing in a Wide Fjord

This paper sets out to test the hypothesis that vertical mixing due to the dissipation of the internal tide accounts for a significant proportion of the total vertical mixing in a fjordic basin during a period of deep water isolation. During July and August 1999 two locations in the Clyde Sea were instrumented with moored RD Instruments Acoustic Doppler Current Profilers (ADCPs) and conductivity-temperature-pressure chains: Station C2, near the shallow entrance sill (55 m water depth), and station C1 in the deep basin (155 m water depth). A bottom pressure recorder was also deployed at station C3 by the seaward entrance to the Clyde Sea in the North Channel of the Irish Sea. A Free-falling Light Yo-yo shear microstructure profiler (FLY) was used to measure the dissipation rate of turbulent kinetic energy (TKE) throughout the water column over 25 h at both C1 and C2. These were interspersed with two-hourly conductivity-temperature-depth casts at both sites. The observations show agreement between the dissipation rate of TKE estimated by using a microstructure profiler and that estimated from the decay of the internal tide as measured by the two ADCPs. However, to account for all the implied mixing it is necessary to invoke an additional source of buoyancy flux, the most probable candidate mechanism is enhanced internal wave breaking near the sill and at the sloping boundaries of the deep basin. In addition, the vertical eddy diffusivity estimated from the micro-structure profiler (O(0.5 cm² s^–1) indicates that internal tide induced mixing away from any boundaries contributed significantly to the overall level of mixing which is required to account for the observed evolution of the deep basin water properties.     

Pilot study for the neonatal screening of fragile X syndrome

An Erratum has been published for this article in Prenatal Diagnosis 23 (9), 2003, 771. Fragile X syndrome (SFX) is the commonest form of inherited mental retardation. Due to the highly variable phenotype clinical diagnosis is complicated. In nearly all cases, the disorder is caused by expansion of a CGG-repeat in the 5′-untranslated region of the FMR1 (fragile X mental retardation-1) gene. We have evaluated the feasibility, efficiency and costs of two methodologies in order to develop a simple test to screen large populations: PCR and fragile X mental retardation-1 protein (FMRP) immunodetection. We studied 100 newborn males using PCR and immunodetection (26.91 Euro). All but one amplified the CGG repeat of the FMR1 gene within the normal size range. The sample that failed to amplify showed only 28% of FMRP expression by immunodetection study; both results indicated an affected male. A further 100 males were studied only by polymerase chain reaction (PCR) (7.8 Euro); all of them amplified within the normal size range. Both methodologies, PCR and immunodetection, are feasible for screening large populations, PCR being the most suitable, economical and less time-consuming. However, it is advisable to keep slides for immunodetection when PCR fails or the external control shows no amplification. Early detection of SFX-affected individuals would represent a great benefit for their maximum social integration, due to appropriate treatment and early stimulation and would permit a cascade screening in their pedigree. Copyright © 2002 John Wiley & Sons, Ltd.