Resilience: What is it and what does it mean for marine policymakers?

Marine policymakers are facing increasing calls to consider the resilience of communities that rely on coastal and marine ecosystem goods and services, and the resilience of natural systems themselves. These calls are in response to increasing threats to coastal communities from external factors such as coastal hazards, possibly associated with climate change, reductions in natural capital often caused by over-fishing and invasive species, and drivers that act to change local and regional economic conditions leading to changes in employment and inequality. However, most communities have had little experience in explicitly managing for resilience. Similarly, our understanding of the factors that make a natural or social system resilient is also somewhat limited. Furthermore, there is a lack of consensus-based definitions and performance measures for assessing resilience. These factors, along with other barriers, will need to be overcome before effective resilience-based management can be implemented.     

Network governance in fisheries

Globalisation is enabling an increasing number of stakeholders to become better informed and more determined to participate in the management of both coastal and high-seas fisheries. Centralised fisheries management agencies are therefore becoming increasingly unable to exert control over the flow of information in fisheries management processes, and less able to exclude other formal and informal institutions from influencing management processes. This work details the emergence of network governance processes and concludes that network governance is likely to erode the traditional command and control authority of many formal government-mandated agencies, and potentially increase the transaction costs in fisheries management processes. However, this style of emergent management may also increase the robustness of management decisions.     

Why ITQs on target species are inefficient at achieving ecosystem based fisheries management outcomes

The effectiveness of managing fisheries through the allocation of catch rights, including Individual Transferrable Quota's (ITQs), has been the subject of a number of recent reviews. Inspection of these reviews suggests that the effectiveness of ITQ and similar catch rights schemes in meeting single species sustainability objectives differs from their effectiveness in meeting broader Ecosystem Based Fisheries Management objectives, especially in terms of managing effects on associated and dependent species and habitats. This should not be a surprise, given the attributes of rights-based neoliberal market policy instruments, as discussed here.     

Remediation technologies for metal-contaminated soils and groundwater: an evaluation

Metals including lead, chromium, arsenic, zinc, cadmium, copper and mercury can cause significant damage to the environment and human health as a result of their mobilities and solubilities. The selection of the most appropriate soil and sediment remediation method depends on the site characteristics, concentration, types of pollutants to be removed, and the end use of the contaminated medium. The approaches include isolation, immobilization, toxicity reduction, physical separation and extraction. Many of these technologies have been used full-scale. This paper will review both the full-scale and developing technologies that are available. Contaminants can be isolated and contained to minimize further movement, to reduce the permeability of the waste to less than 1×10⁻⁷ m/s (according to U.S. guidelines) and to increase the strength or bearing capacity of the waste. Physical barriers made of steel, cement, bentonite and grout walls can be used for isolation and minimization of metal mobility. Another method is solidification /stabilization, which contains the contaminants in an area by mixing or injecting agents. Solidification encapsulates contaminants in a solid matrix while stabilization involves formation of chemical bonds to reduce contaminant mobility. Another approach is size selection processes for removal of the larger, cleaner particles from the smaller more polluted ones. To accomplish this, several processes are used. They include: hydrocyclones, fluidized bed separation and flotation. Addition of special chemicals and aeration in the latter case causes these contaminated particles to float. Electrokinetic processes involve passing a low intensity electric current between a cathode and an anode imbedded in the contaminated soil. Ions and small charged particles, in addition to water, are transported between the electrodes. This technology have been demonstrated in the U.S. full-scale, in a limited manner but in Europe, it is used for copper, zinc, lead, arsenic, cadmium, chromium and nickel. The duration of time that the electrode remains in the soil, and spacing is site-specific. Techniques for the extraction of metals by biological means have been not extensively applied up to this point. The main methods include bioleaching and phytoremediation. Bioleaching involves Thiobacillus sp. bacteria which can reduce sulphur compounds under aerobic and acidic conditions (pH 4) at temperatures between 15 and 55°C. Plants such as Thlaspi, Urtica, Chenopodium, Polygonum sachalase and Alyssim have the capability to accumulate cadmium, copper, lead, nickel and zinc and can therefore be considered as an indirect method of treating contaminated soils. This method is limited to shallow depths of contamination. Soil washing and in situ flushing involve the addition of water with or without additives including organic and inorganic acids, sodium hydroxide which can dissolve organic soil matter, water soluble solvents such as methanol, nontoxic cations, complexing agents such as ethylenediaminetetraacetic acid (EDTA), acids in combination with complexation agents or oxidizing/reducing agents. Our research has indicated that biosurfactants, biologically produced surfactants, may also be promising agents for enhancing removal of metals from contaminated soils and sediments.

In summary, the main techniques that have been used for metal removal are solidification/stabilization, electrokinetics, and in situ extraction. Site characteristics are of paramount importance in choosing the most appropriate remediation method. Phytoremediation and bioleaching can also be used but are not as well developed.     

Estimating the world's potentially available cropland using a bottom-up approach

Previous estimates of the land area available for future cropland expansion relied on global-scale climate, soil and terrain data. They did not include a range of constraints and tradeoffs associated with land conversion. As a result, estimates of the global land reserve have been high. Here we adjust these estimates for the aforementioned constraints and tradeoffs. We define potentially available cropland as the moderately to highly productive land that could be used in the coming years for rainfed farming, with low to moderate capital investments, and that is not under intact mature forests, legally protected, or already intensively managed. This productive land is underutilized rather than unused as it has ecological or social functions. We also define potentially available cropland that accounts for trade-offs between gains in agricultural production and losses in ecosystem and social services from intensified agriculture, to include only the potentially available cropland that would entail low ecological and social costs with conversion to cropland. In contrast to previous studies, we adopt a “bottom-up” approach by analyzing detailed, fine scale observations with expert knowledge for six countries or regions that are often assumed to include most of potentially available cropland. We conclude first that there is substantially less potential additional cropland than is generally assumed once constraints and trade offs are taken into account, and secondly that converting land is always associated with significant social and ecological costs. Future expansion of agricultural production will encounter a complex landscape of competing demands and tradeoffs.     

Killing Carp (Cyprinus carpio) as a Volunteer Practice: implications for community involvement in invasive species management and policy

Community engagement is understood to be one of the keys to successful environmental programs—‘the social pillar’ of management. In this paper we examine community engagement where volunteers participate by killing invasive animals. Most research to date focuses on the biological or management implications of volunteer efforts for the invasive species, with little attention to the people involved or the social acceptability of killing animals in this context. Here, we report on a survey and participant observations of community fishing events in south-eastern Australia, where volunteers fish for and kill carp (Cyprinus carpio). We examine who takes part in these events, their motivations for being involved and the implications for ongoing community engagement. Survey respondents were predominantly well-educated Australian-born men, motivated to fish by a desire to spend time in nature. However, we also noted a strong response from overseas-born men with different motivations. Our survey elicited complex responses regarding killing, illustrating contradictory, sometimes conflicted experiences, which jar with personal motivations. The implications are that questions of ethics must extend to the human volunteers, and that more direct communication of program outcomes and the proposed benefits for volunteers be more rigorously assessed. We argue that invasive species management must contend with the experiences of volunteers, otherwise meaningful dialogue and program objectives risk being undermined.     

Implementation barriers to establishing a sustainable coastal aquaculture sector

For much of the last century, the prerequisites for establishing a new primary industry were property rights to secure access to the required natural resources, the appropriate technology, brood stock and labour, and a willing investor. In contrast, in many western nations although all these prerequisites have been in place for the establishment of new coastal marine farming sectors, fledgling aquaculture operations have failed to establish. A prime reason for this is that under increasingly consultative integrated coastal zone management regimes, local stakeholders are expressing a desire for prospective aquaculture operations to demonstrate that they will be sustainable. Many potential marine farmers and regulatory authorities have stumbled on this demand and the work presented here aims to elucidate the nature of sustainability in a coastal aquaculture context and provide a framework for investigating these critical ‘non-traditional’ factors limiting the establishment and development of coastal aquaculture activities.     

Exploration of structure and bonding in stishovite with fourier and pseudoatom refinement methods using single crystal and powder X-ray diffraction data

The structure and bonding in stishovite, SiO₂, is explored with Fourier summation and pseudoatom refinement of merged x-ray single crystal and powder diffraction data. Replacement of the 25 lowest-angle, highly extinction-affected, single crystal reflections with structure factors obtained from low-extinction powder diffraction data has resulted in a significant improvement in the analysis compared with earlier studies. The deformation electron density, total electrostatic potential and total and valence electron densities are mapped. Accumulations of electron density are observed in both SiO bonds, together with non-bonding features displayed about the oxygen on both sides of a plane formed by three bonds with Si. Deficits of electron density between O atoms across the shared-edges are rationalized in terms of the Pauli exclusion principle. There is no evidence for strong repulsion of Si atoms across the same ring. The total electrostatic potential has a continuous low value for the vacant channels in the structure along c with localized minima between O atoms on opposite sides of the channel. The sizes of Si and O are related to the electron density and to the electrostatic potential.     

Atomic and ionic radii: a comparison with radii derived from electron density distributions

 The bonded radii of anions obtained in topological analyses of theoretical and experimental electron density distributions differ from atomic, ionic and crystal radii in that oxide-, fluoride-, nitride- and sulfide-anion radii are not constant for a given coordination number. They vary in a regular way with bond length and the electronegativity of the cation to which they are bonded, exhibiting radii close to atomic radii when bonded to a highly electronegative cation and radii close to ionic radii when bonded to a highly electropositive cation. The electron density distributions show that anions are not spherical but exhibit several different radii in different bonded directions. The bonded radii of cations correlate with ionic and atomic radii. But unlike ionic radii, the bonded radius of a cation shows a relatively small increase in value with an increase in coordination number. In contrast to atomic and ionic radii, the bonded radius of an ion in a crystal or molecule can be used as a reliable and well-defined estimate of its radius in the direction of its bonds. Received April 16, 1996 / Revised, accepted August 6, 1996