Brian Leung

Biological invasions: recommendations for U.S. policy and management.

The Ecological Society of America has evaluated current U.S. national policies and practices on biological invasions in light of current scientific knowledge. Invasions by harmful nonnative species are increasing in number and area affected; the damages to ecosystems, economic activity, and human welfare are accumulating. Without improved strategies based on recent scientific advances and increased investments to counter invasions, harm from invasive species is likely to accelerate. Federal leadership, with the cooperation of state and local governments, is required to increase the effectiveness of prevention of invasions, detect and respond quickly to new potentially harmful invasions, control and slow the spread of existing invasions, and provide a national center to ensure that these efforts are coordinated and cost effective. Specifically, the Ecological Society of America recommends that the federal government take the following six actions: (1) Use new information and practices to better manage commercial and other pathways to reduce the transport and release of potentially harmful species; (2) Adopt more quantitative procedures for risk analysis and apply them to every species proposed for importation into the country; (3) Use new cost-effective diagnostic technologies to increase active surveillance and sharing of information about invasive species so that responses to new invasions can be more rapid and effective; (4) Create new legal authority and provide emergency funding to support rapid responses to emerging invasions; (5) Provide funding and incentives for cost-effective programs to slow the spread of existing invasive species in order to protect still uninvaded ecosystems, social and industrial infrastructure, and human welfare; and (6) Establish a National Center for Invasive Species Management (under the existing National Invasive Species Council) to coordinate and lead improvements in federal, state, and international policies on invasive species. Recent scientific and technical advances provide a sound basis for more cost-effective national responses to invasive species. Greater investments in improved technology and management practices would be more than repaid by reduced damages from current and future invasive species. The Ecological Society of America is committed to assist all levels of government and provide scientific advice to improve all aspects of invasive-species management.

An ounce of prevention or a pound of cure: bioeconomic risk analysis of invasive species

Numbers of non–indigenous species—species introduced from elsewhere—are increasing rapidly worldwide, causing both environmental and economic damage. Rigorous quantitative risk–analysis frameworks, however, for invasive species are lacking. We need to evaluate the risks posed by invasive species and quantify the relative merits of different management strategies (e.g. allocation of resources between prevention and control). We present a quantitative bioeconomic modelling framework to analyse risks from non–indigenous species to economic activity and the environment. The model identifies the optimal allocation of resources to prevention versus control, acceptable invasion risks and consequences of invasion to optimal investments (e.g. labour and capital). We apply the model to zebra mussels (Dreissena polymorpha), and show that society could benefit by spending up to US

Economic Impacts of Non-Native Forest Insects in the Continental United States

324 000 year−1 to prevent invasions into a single lake with a power plant. By contrast, the US Fish and Wildlife Service spent US

Fluctuating Asymmetry as a Bioindicator of Stress: Comparing Efficacy of Analyses Involving Multiple Traits

825 000 in 2001 to manage all aquatic invaders in all US lakes. Thus, greater investment in prevention is warranted.

Fluctuating asymmetry in relation to stress and fitness: Effects of trait type as revealed by meta-analysis

Reliable estimates of the impacts and costs of biological invasions are critical to developing credible management, trade and regulatory policies. Worldwide, forests and urban trees provide important ecosystem services as well as economic and social benefits, but are threatened by non-native insects. More than 450 non-native forest insects are established in the United States but estimates of broad-scale economic impacts associated with these species are largely unavailable. We developed a novel modeling approach that maximizes the use of available data, accounts for multiple sources of uncertainty, and provides cost estimates for three major feeding guilds of non-native forest insects. For each guild, we calculated the economic damages for five cost categories and we estimated the probability of future introductions of damaging pests. We found that costs are largely borne by homeowners and municipal governments. Wood- and phloem-boring insects are anticipated to cause the largest economic impacts by annually inducing nearly

Modelling fluctuating asymmetry in relation to stress and fitness

1.7 billion in local government expenditures and approximately

Boats, Pathways, and Aquatic Biological Invasions: Estimating Dispersal Potential with Gravity Models

830 million in lost residential property values. Given observations of new species, there is a 32% chance that another highly destructive borer species will invade the U.S. in the next 10 years. Our damage estimates provide a crucial but previously missing component of cost-benefit analyses to evaluate policies and management options intended to reduce species introductions. The modeling approach we developed is highly flexible and could be similarly employed to estimate damages in other countries or natural resource sectors.

Developing Conceptual Frameworks for the Recovery of Aquatic Biota from Acidification

Researchers have suggested fluctuating asymmetry (FA) as an indicator of environmental stress and have usually tested this assertion by examining relations between FA of single traits and stress. Fluctuating asymmetry stress relations are real but are typically weak and difficult to detect. Researchers would like to maximize the probability of detecting FA‐stress relations when they exist. We assert that analyses based on the FA of multiple traits may provide better methods for detecting stress. In this article, we used computer simulations to compare the ability of six analyses to detect differences in FA between stressed and unstressed populations. We show that the optimal analysis depends upon the underlying form of the FA distributions. We also show that two of the analyses had inflated Type I errors in some situations. Finally, we quantify the advantage of our preferred analysis over those of single‐trait FA in detecting stress.

Is invasion history a useful tool for predicting the impacts of the world's worst aquatic invasive species?

Abstract:Recently, there has been much controversy over whether fluctuating asymmetry (FA) is related to stress during development, or to fitness of organisms following development. Many tests have found the predicted relations, whereas others have not. To account for these inconsistencies, some researchers have argued that FA of some traits (e.g., sexually selected traits) are more sensitive measures of stress, or are more strongly related to fitness, and that such relations will differ between poikilotherms and homeotherms. Using meta-analysis, we found that FA-stress and FA-fitness relations were non-spurious, despite the large number of relations tested. However, FA-stress and FA-fitness relations were fairly weak and highly heterogenous. Furthermore, our results suggested that trait type was not predictive of the presence or strength of FA-stress or FA-fitness relations and that relations were not stronger for poikilotherms, as one hypothesis suggested.

Using ecological niche models to predict the abundance and impact of invasive species: application to the common carp

Fluctuating asymmetry (or FA) refers to directionally random deviations from bilateral symmetry for a character pair of an organism. Character FA has been related to stress imposed during development of organisms and quality or fitness of individuals. However, FA-stress and FA-quality relations often are absent or variable depending on the characters assessed. Some researchers have hypothesized that FA of sexually selected traits may relate to stress and fitness more reliably than other traits, and that genetic predispositions towards asymmetry may confound relations between asymmetry and either stress or quality. Others have suggested that because character FA is generated randomly, it may not relate to fitness or to FAs of other characters within samples of individuals. In this paper, we modelled development of character FA in relation to random developmental noise or perturbations, stress, developmental stability, and individual quality. We concluded that FA of sexually selected traits need not relate to stress or individual quality more than FA of other characters. We also determined that, in the absence of confounding factors such as genetic predispositions toward asymmetry, measurement error, and character FA-size relations, FA of some characters need not relate to stress or quality. Interestingly, leptokurtic asymmetry distributions could be generated using models expected to generate true FA; thus, leptokurtic asymmetry distributions should be assayed for relations with stress and fitness. We also found that unsigned FA could reliably relate to organism-wide developmental stability and quality, even in the absence of organism-wide FA relations among traits. Finally, conclusions about the utility of FA measures will depend strongly on representation of high FA individuals in samples, because FA-quality relations were typically triangular in distribution.