Genetic subdivision within the eastern Australian population of the sea anemoneActinia tenebrosa

An electrophoretic survey of allozyme variation revealed substantial genetic differentiation within the eastern Australian population ofActinia tenebrosa. This differentiation appears to reflect the effects of both asexual reproduction and limited gene flow among local populations separated by up to 1050 km. Variation was assessed within groups of 27 to 55 adults sampled between September 1985 and December 1988 collected from small areas of shore within each of 24 local populations. All individuals were collected from stable rock platforms, with the exception of Boulder Bay, where some sea anemones were removed from small mobile boulders. High levels of variability were detected for each of seven enzyme-encoding loci. The patterns of genotypic variation detected imply that local populations are maintained by predominantly asexually generated recruitment. Levels of multi-locus genotypic diversity within samples were consistently less than 50% of the level expected for sexual reproduction with free recombination. This was reflected by the detection of relatively low numbers of multi-locus genotypes and significant departures from expectations for single-locus Hardy-Weinberg equilibria within 17 of the 24 local populations. Standardised genetic variances (F _ST ), calculated from the genotypes of all individual adults were typically much greater than those expected for marine organisms with widely dispersed larvae. The former values were reduced, but were still extremely large when clonal genotype frequencies were substituted into the calculation. These data imply that although widely dispersed larvae may be an important source of initial colonists, levels of gene flow among established local populations are low. Furthermore, cluster analysis revealed a clear subdivision of the population into northern and southern groups. However, this subdivision was largely explained by strong clinal variation at a GPI-encoding locus. For this locus, allele frequencies ranged from fixation of the A allele in samples from the 12 most northern sites to near fixation of the alternative B allele in southern samples. Subdivision of the eastern Australian population is consistent with the predicted off-shore movement of the Eastern Australian Current close to the border between Victoria and New South Wales. However, the split into northern and southern regions, as evidenced by the variation forGpi, could reflect patterns of gene flow and/or other factors such as natural selection or the recent patterns of colonisation.Contribution No. 78 from the Ecology and Genetics Group of the University of Wollongong     

Monitoring the movements of harbour porpoises (Phocoena phocoena) with satellite telemetry

The movements of nine harbour porpoises, Phocoena phocoena (L.), in the Bay of Fundy and Gulf of Maine were tracked using satellite telemetry. Transmitters were attached to the porpoises in August 1994 and 1995 after they were captured near Grand Manan Island at the mouth of the Bay of Fundy. Tracking periods ranged from 2 to 212 d (mean 50 ± 65 d). Porpoises exhibited a high degree of individual variation in movement patterns; five moved out of the Bay of Fundy into the Gulf of Maine. The porpoise with the longest tracking period moved extensively throughout the Gulf of Maine. These data suggest that seasonal movement patterns of individual harbour porpoises are discrete and are not temporally coordinated migrations. Porpoises that moved out of the Bay of Fundy into the Gulf of Maine did so following the 92 m isobath, which may represent an important movement corridor. The movement of porpoises from the Bay of Fundy into the Gulf of Maine supports the hypothesis that harbour porpoises from these two regions comprise a single population at risk of entanglement in both Canadian and US fisheries. Received: 4 February 1997 / Accepted: 25 August 1997     

A two-column method for long-term monitoring of non-methane hydrocarbons (NMHCs) and oxygenated volatile organic compounds (o-VOCs)

A method has been developed for concurrent analysis of C2-C7 hydrocarbons and C2-C5 oxygenated volatile organic compounds (o-VOCs) including alcohols, aldehydes, ketones and ethers. A multi-bed, Peltier-cooled adsorbent trap, consisting of Carboxen 1000 and Carbopack B, was used to acquire one sample per hour. Upon injection the sample was split in an approximately 50:50 ratio between a 50 m aluminium oxide (Al2O3) porous layer open tubular (PLOT) column and a 10 m LOWOX column. Eluents from each column were then analysed using flame ionisation detection (FID). Regular calibration of the system was performed using a standard cylinder mixture at the parts per billion by volume (ppbV) level for non-methane hydrocarbons (NMHCs) and a permeation tube method for the oxygenated species. The system is fully automated with NMHC detection limits between 1 and 10 parts per trillion by volume (pptV) and o-VOC detection limits between 10 and 40 pptV.     

Exploring the internal and external wildlife gradients created by conservation fences

Spillover effects are an expansion of conservation benefits beyond protected areas through dispersal of species that reside within. They have been well documented in marine but not terrestrial systems. To understand the effects on wildlife created by conservation fences, we explored the internal and external gradients of activity in mammal, reptile, and bird species at a conservation reserve in arid Australia that is fenced to exclude invasive rabbits (Oryctolagus cuniculus), cats (Felis catus), and foxes (Vulpes vulpes). Two methods were used: counts of animal tracks along transects on sand dunes and captures at pitfall-trapping sites. In both cases, sites were spaced at different distances from the reserve fenceline inside and outside the reserve. We recorded a range of spillover, source-sink, step, and barrier effects that combined to create a zone within and around the reserve with fence-induced species-specific wildlife gradients. Two endemic rodents but none of the 4 mammal species reintroduced to the reserve showed positive spillover effects. Barrier effects, where activity was highest close to the fence, were recorded for the feral cat and native bettong (Bettongia lesueur), species that could not breach the fence. In comparison, some reptiles and native mammal species that could permeate the fence displayed source-sink effects; that is, their activity levels were reduced close to the fence likely due to constant emigration to the side with lower density. Activity of some reptiles was lowest at sites inside the reserve and gradually increased at outside sites with distance from the fence, a gradient likely related to trophic cascades triggered by predator exclusion. Our result shows that fenced reserves can create overlapping layers of species-specific gradients related to each species’ ability to permeate the fence and its varying susceptibility to threats. Managers should be aware that these gradients may extend for several kilometers either side of the fence and that not all contained species will increase in abundance. Creating wider conservation benefits may require increased fence permeability and threat reduction outside the fence.     

Perpetual landfilling through aeration of the waste mass; lessons from test cells in Georgia (USA).

Municipal solid waste (MSW) landfills worldwide are experiencing the consequences of conventional landfilling techniques, whereby anaerobic conditions are created within the landfilled waste. Under anaerobic conditions within a landfill site slow stabilization of the waste mass occurs, producing methane, (an explosive 'green house' gas) and leachate (which can pollute groundwater) over long periods of time. As a potential solution, it was demonstrated that the aerobic degradation of MSW within a landfill can significantly increase the rate of waste decomposition and settlement, decrease the methane production and leachate leaving the system, and potentially increase the operational life of the site. Readily integrated into the existing landfill infrastructure, this approach can safely and cost-effectively convert a MSW landfill from anaerobic to aerobic degradation processes, thereby effectively composting much of the organic portions (one of the potentially polluting elements in a conventional landfill site) of the waste. This paper summarizes the successful results of two separate aerobic landfill projects located in Georgia (USA) and discusses the potential economic and environmental impacts to worldwide solid waste management practices.     

Urban stormwater runoff pollutant loadings: GIS land use classification vs. sample-based predictions

Environmental Science and Pollution Research - Cities are growing worldwide with an increase in stormwater quantity and decrease in quality, negatively impacting receiving water bodies. The...     

Age-size plasticity for reproduction in monocarpic plants

Empirical and theoretical investigations of monocarpy have usually addressed the question of minimum or threshold sizes for reproduction. However, the range of flowering sizes observed in many monocarpic species is extraordinarily large (well beyond what can be called a "threshold"), and the sizes of flowering and nonflowering plants may overlap greatly. We attempt to explain these reproductive patterns in terms of optimal reaction norms predicted by simple deterministic life history models. We assume that individuals differ in their growth trajectories due to the heterogeneous quality of microsites and ask how the optimal age and size at flowering varies with environmental variation in growth and for different assumptions about fecundity and mortality. Under two very different growth functions (one with no age- or size-related decline in growth rate and another with such a decline as size approaches an asymptote), the optimal reaction norms imply considerable plasticity for size at reproduction, particularly when poor growth is associated with higher mortality or lower asymptotic size. Deterministic models such as these may be more applicable to long-lived than to short-lived monocarps, because fitness potential should be less affected by stochastic variability in yearly growing condition in the former than in the latter. We consider the case of a tropical monocarpic and masting tree species, Cerberiopsis candelabra (Apocynaceae), and show that our model results can account for wide ranges of reproductive size and overlap in size of flowering and nonflowering plants, in accord with observation. We suggest that empirical attention to norms of reaction across growth environments will be a more profitable approach than investigation of size thresholds per se.     

Status of Marine Mammals in the United States

Abstract: The 1994 amendments to the U.S. Marine Mammal Protection Act required, for the first time, an assessment of the status of every marine mammal stock in the United States. We draw conclusions about the status of marine mammals from assessments of 153 stocks conducted to meet the requirements of these amendments. We found important regional differences in the status of stocks. Most stocks in the Atlantic and Pacific experience human-induced mortality (takes), primarily from gill-net fisheries. The proportion of stocks with takes was lower in the Gulf of Mexico and Hawaii, areas with few gill-net fisheries. Estimated takes exceeded removal limits for 29% of stocks in the Atlantic, 14% in the Pacific, 8% in Alaska, 7% in the Gulf of Mexico, and 0% in Hawaii. Twenty-eight stocks are listed as threatened or endangered under the U.S. Endangered Species Act. Most, but not all, baleen whale stocks are recovering after cessation of commercial harvests. Many species of pelagic cetaceans, including beaked and sperm whales, are vulnerable to mortality in pelagic drift-net fisheries. Most pinniped stocks experience takes, but none of these takes exceeds removal limits, and all pinniped stocks on mainland coasts of the United States are increasing in abundance. Quantitative data on trends in abundance are available for few cetacean stocks, emphasizing the difficulty of monitoring trends in these species. These stock assessments have greatly advanced our understanding of the status of marine mammals in the United States, but information gaps remain, particularly regarding stock structure and possible mortality in unmonitored fisheries.     

The migration of uranium into peat-rich soils at Broubster, Caithness, Scotland, U.K.

Uranium is being actively transported from uraniferous sedimentary rocks into a peat bog at the Broubster natural analogue site in Caithness, Scotland. Massive calcareous sandstone within the Caithness Flags sequence is the main source of uranium which resides primarily within diagenetic apatite and dispersed U---Si---Ti phases. Supergene weathering processes have decalcified the sandstone and are effective in mobilising uranium by groundwater leaching, primarily along a fault zone. Uranium transport in solution by means of groundwater and surface flows is effectively terminated by retardation within 4-kyr-old peat deposits laid down on boulder clay. This process of secondary fixation has resulted in a young uranium anomaly in the peat which comprises in excess of 0.1 wt% U. The site has been investigated comprehensively to define the geometry of the anomaly together with the hydrogeology, hydrochemistry, petrology, mineralogy and the nature of the peat sink-term. The main physical and geochemical properties of the system, including the uranium decay series radionuclide distributions in water and solid samples, are documented in this paper. From these data, the processes governing the distribution of uranium have been quantified using a three-dimensional groundwater flow package and an equilibrium speciation model incorporating a recently developed electrostatic surface complexation model to account for cation-organic interactions. The results described form part of a coordinated project on natural radionuclide migration undertaken to improve confidence in predictive methods used for radiological assessment.