The complex network of global cargo ship movements

Transportation networks play a crucial role in human mobility, the exchange of goods, and the spread of invasive species. With 90% of world trade carried by sea, the global network of merchant ships provides one of the most important modes of transportation. Here we use information about the itineraries of 16,363 cargo ships during the year 2007 to construct a network of links between ports. We show that the network has several features which set it apart from other transportation networks. In particular, most ships can be classified in three categories: bulk dry carriers, container ships and oil tankers. These three categories do not only differ in the ships' physical characteristics, but also in their mobility patterns and networks. Container ships follow regularly repeating paths whereas bulk dry carriers and oil tankers move less predictably between ports. The network of all ship movements possesses a heavy-tailed distribution for the connectivity of ports and for the loads transported on the links with systematic differences between ship types. The data analyzed in this paper improve current assumptions based on gravity models of ship movements, an important step towards understanding patterns of global trade and bioinvasion.Comment: 7 figures Accepted for publication by Journal of the Royal Society Interface (2010) For supplementary information, see http://www.icbm.de/~blasius/publications.htm

Classification of non-indigenous species based on their impacts: Considerations for application in marine management

Assessment of the ecological and economic/societal impacts of the introduction of non-indigenous species (NIS) is one of the primary focus areas of bioinvasion science in terrestrial and aquatic environments, and is considered essential to management. A classification system of NIS, based on the magnitude of their environmental impacts, was recently proposed to assist management. Here, we consider the potential application of this classification scheme to the marine environment, and offer a complementary framework focussing on value sets in order to explicitly address marine management concerns. Since existing data on marine NIS impacts are scarce and successful marine removals are rare, we propose that management of marine NIS adopt a precautionary approach, which not only would emphasise preventing new incursions through pre-border and at-border controls but also should influence the categorisation of impacts. The study of marine invasion impacts requires urgent attention and significant investment, since we lack the luxury of waiting for the knowledge base to be acquired before the window of opportunity closes for feasible management

Optimal control of spatial-dynamic processes: The case of biological invasions

This study examines the spatial nature of optimal bioinvasion control. We develop and parameterize a spatially explicit two-dimensional model of species spread that allows for differential control across space and time, and we solve for optimal control strategies. We find that the qualitative nature of optimal strategies depend in interesting ways on aspects of landscape and invasion geometry. For example, we show that reducing the extent of exposed invasion edge, through spread, removal, or strategically employing landscape features, can be an optimal strategy because it reduces long-term containment costs. We also show that optimal invasion control is spatially and temporally “forward-looking” in the sense that strategies should be targeted to slow the spread of an invasion in the direction of greatest potential long-term damages. These and other novel findings contribute to the largely nonspatial literature on optimally controlling invasions and to understanding control of spatial-dynamic processes in general.invasive species, spatial-dynamic processes, spatial spread, reaction-diffusion, management, cellular automaton, eradication, containment, spatial control, integer programming, Environmental Economics and Policy, Land Economics/Use, Resource /Energy Economics and Policy, Q, Q1, Q2, Q5,

Spatial Analysis: Development of Descriptive and Normative Methods with Applications to Economic-Ecological Modelling

This paper adapts Turing analysis and applies it to dynamic bioeconomic problems where the interaction of coupled economic and ecological dynamics over space endogenously creates (or destroys) spatial heterogeneity. It also extends Turing analysis to standard recursive optimal control frameworks in economic analysis and applies it to dynamic bioeconomic problems where the interaction of coupled economic and ecological dynamics under optimal control over space creates a challenge to analytical tractability. We show how an appropriate formulation of the problem reduces analysis to a tractable extension of linearization methods applied to the spatial analog of the well known costate/state dynamics. We illustrate the usefulness of our methods on bioeconomic applications, but the methods have more general economic applications where spatial considerations are important. We believe that the extension of Turing analysis and the theory associated with dispersion relationship to recursive infinite horizon optimal control settings is new.Spatial analysis, Economic-ecological modelling

Spatial Analysis: Development of Descriptive and Normative Methods with Applications to Economic-Ecological Modelling

This paper adapts Turing analysis and applies it to dynamic bioeconomic problems where the inter- action of coupled economic and ecological dynamics over space endogenously creates (or destroys) spatial heterogeneity. It also extends Turing analysis to standard recursive optimal control frame- works in economic analysis and applies it to dynamic bioeconomic problems where the interaction of coupled economic and ecological dynamics under optimal control over space creates a challenge to analytical tractability. We show how an appropriate formulation of the problem reduces analysis to a tractable extension of linearization methods applied to the spatial analog of the well known costate/state dynamics. We illustrate the usefulness of our methods on bioeconomic applications, but the methods have more general economic applications where spatial considerations are important. We believe that the extension of Turing analysis and the theory associated with dispersion relationship to recursive in…nite horizon optimal control settings is new.Spatial analysis, Pattern formation, Turing mechanism, Optimal control, bioeconomic problems

Introduced Species in United States Coastal Waters

This pdf document commissioned by the Pew Ocean Commission describes the problem of invasive species along the United States coastline. The document provides information regarding how bioinvasions occur, the number of invasive species introduced, the effects of bioinvasions, prevention, reduction and control of marine bioinvasions and recommendations for action against invasive species invasion. The pdf also provides a glossary of bioinvasion terms. Educational levels: Graduate or professional, Undergraduate lower division, Undergraduate upper division

THE DILEMMA OF SAFER AND FREER TRADE: THE CASE OF THE U.S. NURSERY INDUSTRY

Crop Production/Industries, International Relations/Trade,