Social preferences for the design of biodiversity offsets for shorebirds in Australia

Understanding the social acceptability of biodiversity offsets is important to the design of offset policy. We used a discrete choice experiment to quantify preferences of Australians for a migratory shorebird offset in the context of an oil and gas development project. We surveyed a nationally representative sample of 1371 respondents on their preferences for current and prospective offset‐policy characteristics via an online questionnaire to inform policy design of the social dimensions related to offset acceptability. The majority of respondents accepted offsetting as a means to allow economic development; the option to reject development (and an offset) was selected in 13% of possible offset scenarios. Substituting protection of a species affected by the development with protection of a more endangered species was a desirable policy characteristic, as was having the offset implemented by a third party or the government rather than the company responsible for the development. Direct offset activities (e.g., improving degraded habitat) were preferred over indirect activities (e.g., a research program), and respondents were strongly against locating the offset at a site other than where the impact occurred. Positive and negative characteristics of offsets could be traded off by changing the number of birds protected by the offset. Our results show that Australians are likely to support increased flexibility in biodiversity‐offset policies, particularly when undesirable policy characteristics are compensated for.     

The relationship between adaptation and mitigation in managing climate change risks: a regional response from North Central Victoria,Australia

This two-part paper considers the complementarity between adaptation and mitigation in managing the risks associated with the enhanced greenhouse effect. Part one reviews the application of risk management methods to climate change assessments. Formal investigations of the enhanced greenhouse effect have produced three generations of risk assessment. The first led to the United Nations Intergovernmental Panel on Climate Change (IPCC), First Assessment Report and subsequent drafting of the United Nations Framework Convention on Climate Change. The second investigated the impacts of unmitigated climate change in the Second and Third IPCC Assessment Reports. The third generation, currently underway, is investigating how risk management options can be prioritised and implemented. Mitigation and adaptation have two main areas of complementarity. Firstly, they each manage different components of future climate-related risk. Mitigation reduces the number and magnitude of potential climate hazards, reducing the most severe changes first. Adaptation increases the ability to cope with climate hazards by reducing system sensitivity or by reducing the consequent level of harm. Secondly, they manage risks at different extremes of the potential range of future climate change. Adaptation works best with changes of lesser magnitude at the lower end of the potential range. Where there is sufficient adaptive capacity, adaptation improves the ability of a system to cope with increasingly larger changes over time. By moving from uncontrolled emissions towards stabilisation of greenhouse gases in the atmosphere, mitigation limits the upper part of the range. Different activities have various blends of adaptive and mitigative capacity. In some cases, high sensitivity and low adaptive capacity may lead to large residual climate risks; in other cases, a large adaptive capacity may mean that residual risks are small or non-existent. Mitigative and adaptive capacity do not share the same scale: adaptive capacity is expressed locally, whereas mitigative capacity is different for each activity and location but needs to be aggregated at the global scale to properly assess its potential benefits in reducing climate hazards. This can be seen as a demand for mitigation, which can be exercised at the local scale through exercising mitigative capacity. Part two of the paper deals with the situation where regional bodies aim to maximise the benefits of managing climate risks by integrating adaptation and mitigation measures at their various scales of operation. In north central Victoria, Australia, adaptation and mitigation are being jointly managed by a greenhouse consortium and a catchment management authority. Several related studies investigating large-scale revegetation are used to show how climate change impacts and sequestration measures affect soil, salt and carbon fluxes in the landscape. These studies show that trade-offs between these interactions will have to be carefully managed to maximise their relative benefits. The paper concludes that when managing climate change risks, there are many instances where adaptation and mitigation can be integrated at the operational level. However, significant gaps between our understanding of the benefits of adaptation and mitigation between local and global scales remain. Some of these may be addressed by matching demands for mitigation (for activities and locations where adaptive capacity will be exceeded) with the ability to supply that demand through localised mitigative capacity by means of globally integrated mechanisms.     

DNA Changes in Tissues Entrapped in Plant Resins (the Precursors of Amber)

 There have been many reports characterizing DNA from amber, which is a fossil version of plant resin. Here we report an investigation of the effects of plant resin (from Pseudotsuga menziesii) and drying conditions on the preservation of DNA in biological tissues. We examined the degree of degradation of the DNA by agarose gel electrophoresis of extracted DNA, by polymerase chain reaction, and by DNA sequencing. The plant resin alone appeared to cause little or no damage to DNA. Tissue immersed in plant resin that dried rapidly (exposed to sunlight) contained DNA with little apparent damage. Tissue immersed in the resin that was dried slowly (in shade without sunlight) contained DNA with some degradation (3.5% nucleotide changes). The tissue that was immersed in the resin that was constantly hydrated (by immersion in water) yielded DNA that was severely damaged (50–62% nucleotide changes). Transversions outnumbered transitions in these samples by a ratio of 1.4 : 1. A piece of Baltic amber immersed in water for 5 days appeared to be impervious to the water. Thus amber inclusions that initially dried rapidly have the potential to yield undamaged DNA. Those that dried slowly may contain damaged DNA and may be unsuitable for phylogenetic and other studies. Received: 23 March 1999 / Accepted in revised form: 16 September 1999     

Reproductive isolation among morphotypes of the Atlantic seastar species<Emphasis Type="Italic"> Zoroaster fulgens</Emphasis> (Asteroidea: Echinodermata)

Zoroaster fulgens is a slope-dwelling seastar species that is distributed throughout the Atlantic Ocean. Studies into the population structure and systematics of marine animals have increasingly found that species with a reported cosmopolitan distribution are, in fact, collections of closely related cryptic or sibling species. In the Porcupine Seabight, three morphotypes of Z. fulgens can be found that have a distribution that is stratified by depth. This study investigates the genetic divergence between these morphotypes using sections of the cytochrome oxidase 1 (COI) and 16S regions of the mitochondrial genome. Bathymetrically separated morphotypes of Z. fulgens are reproductively isolated over distances of approximately 1 km while gene flow occurs among morphotypes, along isobaths, over distances of approximately 900 km. Reproductive isolation on the continental slope may have occurred as a result of selection exerted by gradients of depth-correlated physical factors, such as pressure and temperature. However, allopatric speciation with subsequent range expansion may also explain the observed patterns of genetic divergence. Further investigation of radiation within this group may provide important information on the evolution of slope species. Taxonomic revision of the genus is required.Communicated by J.P. Thorpe, Port Erin     

Genetic study of the extent and consequences of sexual and asexual reproduction in the deep-sea epizoic anemones Amphianthus inornata and Kadosactis commensalis (Cnidaria: Anthozoa)

The anemone Amphianthus inornata is found at bathyal depths living on colonies of the gorgonian Acanella arbuscula. Previous studies of the morphology and reproductive stage of this anemone, during different times of the year, have indicated that it reproduces sexually on a seasonal basis. A small proportion of the study population were also reported to be undergoing asexual reproduction by fission. The anemone Kadosactis commensalis is also bathyal, but lives mainly on the holothurian Paroriza prouhoi. Previous morphological studies have indicated that K. commensalis is a protandrous hermaphrodite that exhibits non-seasonal sexual reproduction only. In the present study, allozyme electrophoresis was used to examine the prevalence and genetic consequences of asexual reproduction in a population of Amphianthus inornata from 2 200 m in the Rockall Trough, North Atlantic Ocean. Genetic evidence, from five randomly selected polymorphic enzyme loci, for asexual reproduction in this species was weak. Exact tests indicated that genotype frequencies did not differ significantly from those expected under Hardy–Weinberg equilibrium. F _IS (correlation of homologous alleles with reference to local population, assuming random mating) values also did not differ significantly from zero, and observed heterozygosity (H _o =0.446) and genotypic diversity (G _o =17.0387) were very similar to Hardy–Weinberg expected frequencies (H _e =0.446; G ^* _e =17.0010). Evidence suggests that the contribution of asexual reproduction to recruitment in the study population of A. inornata is low. For a single population of K. commensalis from 4 850 m on the Porcupine Abyssal Plain, North Atlantic Ocean, the hypothesis that inbreeding due to reduced occurrence of outcrossing between anemones on a single holothurian host was examined by electrophoresis of ten randomly selected enzyme loci. Single-locus genotypic frequencies were significantly different from expected frequencies for one locus P≤ 0.05, hexokinase-1 (Hex-1)]. F _IS values were significantly different from zero for two enzyme loci (Hex-1 and Hex-2, P≤ 0.01 and P≤ 0.05, respectively), and the overall observed heterozygosity was lower than the expected heterozygosity (H _o =0.125, H _e =0.140). The hypothesis of inbreeding could not be rejected by the present study, although sample size was small (N=55), leading to possible bias in tests of significance. Genetic variation in A. inornata was higher than that recorded for most eukaryotes, although interlocus sampling error for only five loci is high. High genetic variability has been found in other sea anemones, and has been related to high longevity and mixed reproductive modes. Genetic variation in K. commensalis was in the higher range of that found in other eukaryotes, and is not unusual for anemones. Received: 5 August 1996 / Accepted: 11 December 1996     

Extent and nature of extracellular organic production by the marine coccolithophorid Hymenomonas carterae

Production of extracellular dissolved organic substances by cultures of the marine coccolithophorid Hymenomonas carterae SMBA 254 was investigated by the ¹⁴C-tracer technique. In 4 h incubations, extracellular ¹⁴C production represented 20 to 64% of ¹⁴C incorporation into cell material for cultures nearing, or during stationary growth; for rapidly growing cultures with relatively low cell densities the ¹⁴C-production was only 4 to 10% of incorporation. Intra-and extra-cellular material was fractionated by ion-exchange membrane electrodialysis. Ionic compounds accounted for 40 to 60% of extracellular material; in contrast only 16 to 27% of intracelular metabolites were in this category. Of a range of methods which were investigated, separation of compounds by gel-filtration in conjunction with two-dimensional thin-layer chromatography proved most effective. Up to 80% of extracellular material was of less than 1 800 mol. wt and included carbohydrates and amino acids, with glutamic acid predominating. The intracellular material was more heterogeneous, with a substantially greater proportion of high molecular weight material. The quite distinct compositions show clearly that extracellular production observed in these experiments arose through excretion and was not attributable to cell lysis.     

A quantitative description of vehicle exhaust particle size distributions in a highway tunnel

During the period May 18-May 22, 1999, a comprehensive study was conducted in the Tuscarora Mountain Tunnel on the Pennsylvania Turnpike to measure real-world motor-vehicle emissions. As part of this study, size distributions of particle emissions were determined using a scanning mobility particle sizer. Each measured size distribution consisted of two modes: a nucleation mode with midpoint diameter less than 20 nm and an accumulation mode with midpoint diameter less than 100 nm. The nucleation and accumulation components in some distributions also exhibited second maxima, which implies that such particle size distributions are superpositions of two particle size distributions. This hypothesis was utilized in fitting the particle size distributions that exhibited second maxima with four lognormal distributions, two for the nucleation mode and two for the accumulation mode. The fitting assumed that the observed particle size distribution was a combination of two bimodal log-normal distributions, one attributed to the heavy-duty diesel (HDD) vehicles and another attributed either to a different class of HDD vehicles or to the light-duty spark ignition vehicles. Based on this method, estimated particle production rates were 1.8 x 10(13) and 2.8 x 10(14) particles/vehicle-km for light-duty spark ignition and HDD vehicles, respectively, which agreed with independently obtained estimates.     

Structural marsh management effects on coastal fishes and crustaceans

Structural marsh management, using levees and water-control structures, is used in the coastal zone for many objectives, for example, to reduce marsh loss, to enhance waterfowl habitat, to revegetate open-water areas, and to reduce saltwater intrusion. The literature was evaluated to categorize structural marsh management and to determine some of its effects on fishes and crustaceans. Structural marsh management had positive effects on standing stock of most resident organisms and negative effects on marine-transient organisms. Emigration was negatively affected for both resident and marine-transient organisms. Techniques such as opening structures at critical migration times, designing structures that offer the greatest management flexibility, and using structures to create a flow-through system could reduce these impacts. More effort should be put into monitoring managed areas to determine if the objectives are being met and to evaluate the effects on fishes and crustaceans. Although frequent manipulation could reduce these impacts, the costs and problems incurred may outweigh the anticipated benefits.