The uniform line density has maximum crossing factor

If straight lines of infinite length are placed at random on the plane such that the relative numbers in a range of directions is described by a continuous function then it is proved that the maximum crossings per unit area for a fixed length of line per unit area occurs when the lines are provided equally in each direction.     

Sasi and Marine Conservation in Raja Ampat,Indonesia

Raja Ampat, Indonesia, possesses the greatest diversity of corals and reef fishes on the planet. The area is a priority for marine conservation for the provincial government, local communities, and major international nongovernmental organizations such as The Nature Conservancy and Conservation International. Traditional marine resource management practices in the region, referred to as sasi, have the potential to support conservation objectives. This article contends that while traditional marine resource management systems may support conservation, they must be reinforced by a supportive social structure and governance system to remain relevant in a rapidly changing world. Two villages in Raja Ampat were studied to gain a better understanding of sasi and how this practice has been affected by cultural, political, and economic change. These villages illustrate how the role of religious authorities, access to alternative livelihoods, proximity to urban centers, and capacity for monitoring and enforcement may influence the effectiveness of marine resource management systems. Our research suggests that the continued relevance of sasi in marine resource management relies on the support of influential local leaders and businesses and government regulations that reinforce traditional resource use practices.     

The First Step for the Environmental Management of Australian Beaches: Establishing an Effective Policy Framework

Beach management and coastal management are interwoven and scale-dependent activities in Australia. Present coastal policies are broad and designed for large, national, and statewide scales. They specify ecologically sustainable development as the overarching goal for coastal management and provide the context for beach management. On smaller scales, an approach focusing on the reduction of geomorphic hazards as the basis of beach management was established by the Coastline Hazard Policy, with nonhazard aspects of beach management such as ecological, economic, and social concerns assuming secondary importance. Although beach management can occur effectively under these coastal management arrangements, better guidance is required to make this process as effective and efficient as possible. This guidance - the policy framework - could be better developed for beach management and better integrated with existing coastal management arrangements. While this policy development is not strictly necessary to achieve positive outcomes from beach management, it is necessary to effectively guide implementation of the existing broad coastal policies. Effective goals for beach management are yet to be thought out and clearly articulated in Australia. A good start would be to couple the present goals of ecologically sustainable development and hazards reduction into a coherent goal for beach management. A specific policy for beaches should be developed given the importance of beaches in Australia.     

Estimating the Economic Benefits of Regional Ocean Observing Systems

This article introduces a theme issue of the Coastal Management Journal comprising a set of articles on the potential economic benefits from new investments in coastal ocean observing systems. We describe a methodology to estimate these benefits, and apply this methodology to generate preliminary estimates of such benefits. The approach focuses on coastal ocean observing information within ten geographic regions encompassing all coastal waters of the United States, and within a wide range of industrial and recreational activities including recreational fishing and boating, beach recreation, maritime transportation, search and rescue operations, spill response, marine hazards prediction, offshore energy, power generation, and commercial fishing. Our findings suggest that annual benefits to users are likely to run in the multiple $100s of millions of dollars. The project results should be considered first-order estimates that are subject to considerable refinement as the parameters of regional observing systems are better defined, and as our understanding of user sectors improves.     

Warming Seas in the Coral Triangle: Coral Reef Vulnerability and Management Implications

The highest diversity coral reefs in the world, located in the Coral Triangle, are threatened by a variety of local stresses including pollution, overfishing, and destructive fishing in addition to climate change impacts, such as increasing sea surface temperatures (SSTs), and ocean acidification. As climate change impacts increase, coral reef vulnerability at the ecoregional scale will have an increasingly important influence on conservation management decisions. This project provides the first detailed assessment of past and future climatic stress, thermal variability, and anthropogenic impacts in the Coral Triangle at the ecoregional level, thus incorporating both local (e.g., pollution, development, and overfishing) and global threats (increasing SSTs). The development of marine protected area (MPA) networks across the Coral Triangle is critical for the region to address these threats. Specific management recommendations are defined for MPA networks based on the levels of vulnerability to thermal and local stress. For example, coral reef regions with potentially low vulnerability to thermal stress may be priorities for establishment of MPA networks, whereas high vulnerability regions may require selection and design principles aimed at building resilience to climate change. The identification of climate and other human threats to coral reef systems and ecoregions can help conservation practitioners prioritize management responses to address these threats and identify gaps in MPA networks or other management mechanisms (e.g., integrated coastal management).