The southern African shrub boneseed [Chrysanthemoides monilifera subsp. monilifera (L.) Norl.] is a perennial shrub that is a significant threat to natural ecosystems and is listed as a Weed of National Significance in Australia. In Western Australia (WA) it has spread across peri-urban and natural environments. We assembled a single standardized database containing more than 2,050 presence records for individual plants and 135 absence records at a local population level. We further refined the populations into 89 sites that require different management trajectories due to topography and capacity of land managers to implement control. Forty-nine of these sites were in urban regions and 40 sites were in regional WA. We split these 89 sites into three near-term management goals: watch (12), extirpate (68), and contain (9). The 12 watch sites are those where all available evidence suggests that there have been no new inputs into the seedbank for 15 yr. The 68 sites marked for extirpation are those where delimitation is already achieved or easily achievable, where there have been minimal seed inputs into the soil seedbank in recent years due to consistent surveillance and control, and where surveys for new plants are likely to be efficient to conduct. Finally, for nine sites in urban regions around Perth, we recommend containment in the near term with a longer-term goal to achieve delimitation and extirpation. To achieve the objective of state-level eradication, a coordinated and sustained campaign involving three components—delimitation of all sites, prevention of further inputs into the soil seedbank, and systematic field surveys to remove plants—must commence without delay. While resourcing requirements for delimitation and overall program management are not possible to estimate, our prior experience suggests that it will take at least 1,900 h of on-ground surveying by experienced personnel to achieve extirpation of C. monilifera subsp. monilifera in WA.

This article is a rejoinder to Dr. Massimo Lando’s ‘Stability of maritime boundaries and the challenge of geographical change’ which proposes that positive international law offers no legal basis for the delimitation of fluctuating boundaries and discusses the many complexities involved in the delimitation and management of such boundaries. This rejoinder delves deeper into the main point of contention: the legal basis for fluctuating boundaries. It argues that coastal states have an inherent entitlement to a territorial sea and that Article 15 of The United Nations Convention on the Law of the Sea (UNCLOS) entails a default rule for the establishment of provisional fluctuating boundaries. This limit is not necessarily a strict median line because it may be adjusted by reference to special circumstances. Furthermore, the lack of explicit reference to provisional arrangements in UNCLOS Article 15 should not be read as an indication that there are no provisional boundaries in the absence of boundary agreements.

This article further argues that there are judicial precedents for fluctuating boundary-segments. The Nicaragua v. Honduras decision left a segment of the territorial sea un-delimited, resulting in a partially fluctuating boundary, until otherwise agreed. Moreover, the International Court of Justice (ICJ) explicitly established a mobile boundary-segment in Costa Rica v. Nicaragua but as highlighted by Dr. Lando, this was done with the permission of the parties. Much depends on the claims brought by disputing parties and their stance on fluctuating boundaries but this decision demonstrated the ICJ’s willingness to employ fluctuating boundaries in response to coastal instability.

The eradication of an invasive plant species can provide substantial ecological and economic benefits by eliminating completely the negative effects of the weed and reducing the high cost of continuing control. A 5-yr program toward the eradication of hill raspberry (Rubus niveus Thunb.) in Santiago Island is evaluated using delimitation and extirpation criteria, as well as assessment of the ecological community response to management techniques. Currently, hill raspberry is located in the humid zone of Santiago island. It is distributed over three main infestations, small patches, and many scattered individuals within an area of approximately 1,000 ha. New infestations are constantly being found; every year, new detections add an area of approximately 175 ha. Adult and juvenile individuals are still found, both beyond and within known infestations. Both plant and seed bank density of hill raspberry decreased over time where infestations were controlled. Species composition in the seed bank and existing vegetation were significantly different between areas under intensive control and adjacent uninvaded forest. After 5 yr of intensive management, delimitation of hill raspberry has not been achieved; new populations are found every year, increasing the infested area that requires management. Off-target effects on native species resulting from control efforts seem to be substantial. Although a vast increase in economic investment would allow intensive searching that might enable all individuals to be found and controlled, the resultant disturbance and off-targets effects could outweigh the conservation benefits of eradication.

Because weed eradication programs commonly take 10 or more years to complete, there is a need to evaluate progress toward the eradication objective. We present a simple model, based on information that is readily obtainable, that assesses conformity to the delimitation and extirpation criteria for eradication. It is applied to the program currently targeting the annual parasitic weed, branched broomrape, in South Australia. The model consists of delimitation and extirpation (E) measures plotted against each other to form an ‘eradograph.’ Deviations from the ‘ideal’ eradograph plot can inform tactical responses, e.g., increases in survey and/or control effort. Infestations progress from the active phase to the monitoring phase when no plants have been detected for at least 12 mo. They revert to the active phase upon further detection of plants. We summarize this process for the invasion as a whole in a state-and-transition model. Using this model we demonstrate that the invasion is unlikely to be delimited unless the amount of newly detected infested area decreases, on average, by at least 50% per annum. As a result of control activities implemented, on average approximately 70% (range, 44 to 86%) of active infestations progressed to the monitoring phase in the year following their detection. Simulations suggest that increasing this rate of transition will not increase E to a significant extent. The rate of reversion of infestations from the monitoring phase to the active phase decreased logarithmically with time since last detection, but it is likely that lower rates of reversion would accelerate the trend toward extirpation. Program performance with respect to the delimitation criterion has been variable; performance with respect to the extirpation criterion would be improved considerably by the development and application of cost-effective methods for eliminating branched broomrape soil seed populations.

There has been recent interest in determining the upper limits to the feasibility of weed eradication. Although a number of disparate factors determine the success of an eradication program, ultimately eradication feasibility must be viewed in the context of the amount of investment that can be made. The latter should reflect the hazard posed by an invasion, with greater investment justified by greater threats. In simplest terms, the effort (and hence investment) to achieve weed eradication comprises the detection effort required to delimit an invasion plus the search and control effort required to prevent reproduction until extirpation occurs over the entire infested area. The difficulty of estimating the required investment at the commencement of a weed eradication program (as well as during periodic reviews) is a serious problem. Bioeconomics show promise in determining the optimal approach to managing weed invasions, notwithstanding ongoing difficulties in estimating the costs and benefits of eradication and alternative invasion management strategies. A flexible approach to the management of weed invasions is needed, allowing for the adoption of another strategy when it becomes clear that the probability of eradication is low, owing to resourcing or intractable technical issues. Whether the considerable progress that has been achieved towards eradication of the once massive witchweed invasion can be duplicated for other weeds of agricultural systems will depend to a large extent upon investment (> $250 million over 50 yr in this instance). Weeds of natural ecosystems seem destined to remain more difficult eradication targets for a variety of reasons, including higher impedance to eradication, more difficulty in valuing the benefits arising from eradication, and possibly less willingness to pay from society at large.

To eradicate a weed invasion, its extent must be delimited and each infestation must be extirpated. Measures for both of these criteria are utilized to assess the progress of current eradication programs targeting mikania vine and limnocharis in northern Australia. The known infested area for each species is less than 5 ha and has remained largely static for the last 3 or more years against a backdrop of refined and enhanced detection methods. This suggests that delimitation has been approached, if not achieved. Different methods of detection have their places, relative to the stage of the program and the spatial distribution of infestations. Although all known infestations of both species are effectively monitored and controlled, ongoing emergence from persistent seed banks limits progress towards the extirpation of infestations to a slow, but measurable, rate.

The polar regions stand apart from other areas of the globe because of their severe climate and remoteness. Those conditions have also impacted on the development of the legal regime of the polar regions and led to questions concerning the applicability of general public international law to these regions. The present Article investigates this interaction from the perspective of one specific issue: the establishment of the outer limits of the continental shelf in accordance with Article 76 of the United Nations Convention on the law of the sea. Article 76 at present is being implemented worldwide by coastal States and the polar regions are no exception. The present analysis indicates that the implementation of Article 76 in the polar regions is largely similar to other regions of the world. Article 76 contains an arrangement of considerable legal complexity, which often has to be applied in a complex legal and politico-geographical context. The major differences with other regions are no doubt presented by Antarctica, in which case at least for the moment the process of implementing Article 76 also will not be finalized.

This article is a prospective analysis of whether the established principles for delimitation of the continental shelf within 200 NM will apply for delimitation of outer continental margins. On the basis of the established normative jurisprudence of delimitations within 200 NM it can namely not be ruled out that the established equitable criteria and methods for delimitation, for finding an equitable solution, were solely set to prevail in delimitations within 200 NM.

Title commands delimitation and the title for the zone beyond 200 NM differ from the title within 200 NM. Wherein the distance criterion is the title for the zone within 200 NM, geological and geomorphologic criteria are the basis of the title for the legal continental shelf that extends 200 NM. Accordingly, the established normative principles in delimitation of continental shelves beyond 200 NM are susceptible to differ from the established prevailing principles within 200 NM and may have an important impact on delimitations in the continental outer margins.

In conclusion it is held that the established equitable criteria and methods in order to find an equitable solution in delimitations within 200 NM are likely not to apply mutatis mutandis for delimitations beyond 200 NM

The author reviews an award rendered in March 2002 by a three-member arbitral tribunal established by the government of Canada in order to determine a maritime boundary between two Canadian provinces – Nova Scotia, and Newfoundland and Labrador. The tribunal's Terms of Reference required it to treat the provinces as sovereign states and to apply principles of international maritime boundary law in order to determine the boundary dividing their respective offshore entitlements as defined under domestic federal legislation. Given this reference to international law and the underlying interests at issue, the tribunal's award amounts to a classic continental shelf delimitation and makes significant contributions to the jurisprudence on international maritime boundary delimitation.

The Award of the Arbitral Tribunal in the Second Phase (Maritime Delimitation) of the Eritrea-Yemen Arbitration follows the trend towards producing a single all-purpose delimitation line constructed on the basis of equidistance, the course of which is chiefly dictated by mainland coastal geography. Islands are accorded little impact upon the course of the final line, save to the extent necessary to permit them a full territorial sea. The potential relevance of other factors, including fishing and navigational interests is acknowledged but, given the methodology adopted, they did not influence the construction of the line. As in other cases, proportionality is demonstrated by comparison of areas with the relevant coastal lengths, although the usefulness of this is dubious. Although entirely separate exercises, it may be that the methodology pursued owes something to the outcomes of the first phase of the Arbitration, concerning sovereignty over the islands, and this may have a bearing upon the impact of the Award for maritime boundary delimitation more generally.