Invasive species continue to drive major losses in biodiversity and ecosystem function across the globe. Dealing with the effects of invasion is particularly problematic in marine and freshwater ...habitats, because the pace at which invaders establish often greatly outstrips the resources available for their eradication. While most managers in North America now focus on ongoing containment and suppression interventions, they often lack quantitative guidance from which to set targets and evaluate success. We propose practical guidelines for identifying management targets for invasions for which eradication is unfeasible, based on achieving “functional” eradication – defined as suppressing invader populations below levels that cause unacceptable ecological effects – within high-priority locations. We summarize key ecological information needed to inform this strategy, including density–impact functions and recolonization rates. We illustrate the framework’s application for setting local suppression targets using three globally invasive species as examples: red lionfish (Pterois spp), European green crab (Carcinus maenas), and rusty crayfish (Faxonius rusticus). Identifying targets for suppression allows managers to estimate the degree of removal required to mitigate ecological impacts and the management resources needed to achieve sufficient control of an invader.
Invasive alien species (IAS) threaten human livelihoods and biodiversity globally. Increasing globalization facilitates IAS arrival, and environmental changes, including climate change, facilitate ...IAS establishment. Here we provide the first global, spatial analysis of the terrestrial threat from IAS in light of twenty-first century globalization and environmental change, and evaluate national capacities to prevent and manage species invasions. We find that one-sixth of the global land surface is highly vulnerable to invasion, including substantial areas in developing economies and biodiversity hotspots. The dominant invasion vectors differ between high-income countries (imports, particularly of plants and pets) and low-income countries (air travel). Uniting data on the causes of introduction and establishment can improve early-warning and eradication schemes. Most countries have limited capacity to act against invasions. In particular, we reveal a clear need for proactive invasion strategies in areas with high poverty levels, high biodiversity and low historical levels of invasion.
Extreme climatic events (ECEs) - such as unusual heat waves, hurricanes, floods, and droughts - can dramatically affect ecological and evolutionary processes, and these events are projected to become ...more frequent and more intense with ongoing climate change. However, the implications of ECEs for biological invasions remain poorly understood. Using concepts and empirical evidence from invasion ecology, we identify mechanisms by which ECEs may influence the invasion process, from initial introduction through establishment and spread. We summarize how ECEs can enhance invasions by promoting the transport of propagules into new regions, by decreasing the resistance of native communities to establishment, and also sometimes by putting existing non-native species at a competitive disadvantage. Finally, we outline priority research areas and management approaches for anticipating future risks of unwanted invasions following ECEs. Given predicted increases in both ECE occurrence and rates of species introductions around the globe during the coming decades, there is an urgent need to understand how these two processes interact to affect ecosystem composition and functioning.
To conserve coastal foundation species, it is essential to understand patterns of distribution and abundance and how they change over time. We synthesized oyster distribution data across the west ...coast of North America to develop conservation strategies for the native Olympia oyster (Ostrea lurida), and to characterize populations of the non-native Pacific oyster (Magallana gigas). We designed a user-friendly portal for data entry into ArcGIS Online and collected oyster records from unpublished data submitted by oyster experts and from the published literature. We used the resulting 2,000+ records to examine spatial and temporal patterns and made an interactive web-based map publicly available. Comparing records from pre-2000 vs. post-2000, we found that O. lurida significantly decreased in abundance and distribution, while M. gigas increased significantly. Currently the distribution and abundance of the two species are fairly similar, despite one species being endemic to this region since the Pleistocene, and the other a new introduction. We mapped the networks of sites occupied by oysters based on estimates of larval dispersal distance, and found that these networks were larger in Canada, Washington, and southern California than in other regions. We recommend restoration to enhance O. lurida, particularly within small networks, and to increase abundance where it declined. We also recommend restoring natural biogenic beds on mudflats and sandflats especially in the southern range, where native oysters are currently found most often on riprap and other anthropogenic structures. This project can serve as a model for collaborative mapping projects that inform conservation strategies for imperiled species or habitats.
Biological invasions continue to occur worldwide, resulting in substantial impacts on ecosystems as well as human health and economies (1, 2). One of the fundamental tasks associated with managing ...these invasions is to predict which species are most likely to be future invaders--a task that has become increasingly challenging due to climate change and shifts in the source of potential invaders (3, 4). Scientists have undertaken considerable efforts to manage the potential risk of future invasions by focusing on species that have been introduced previously in other areas, often with considerable impact. Many elegant studies of these repeat offenders have used various combinations of phylogenetic, morphological, and life history characteristics to develop predictive models that predict which species are most likely to invade (5, 6). Most of these studies have relied on the data from the investigations of serial invaders to predict future invasions, and many management programs have placed their emphasis on high-profile invaders that have caused demonstrable damage in other regions (7). In short, scientists and managers have generally relied on information from the track records of previous invasions to predict future invasions. However, a new study in PNAS (8) calls this thinking into question by demonstrating that emerging invaders, species that have never been found outside of their native range, continue to be a significant proportion of new invasions. They also demonstrate that the continuing presence of newly emerging invaders is the result of new source pools contributing to the ongoing stream of invasions.
Biological invasions are rapidly producing planet-wide changes in biodiversity and ecosystem function. In coastal waters of the U.S., >500 invaders have become established, and new introductions ...continue at an increasing rate. Although most species have little impact on native communities, some initially benign introductions may occasionally turn into damaging invasions, although such introductions are rarely documented. Here, I demonstrate that a recently introduced crab has resulted in the rapid spread and increase of an introduced bivalve that had been rare in the system for nearly 50 yr. This increase has occurred through the positive indirect effects of predation by the introduced crab on native bivalves. I used field and laboratory experiments to show that the mechanism is size-specific predation interacting with the different reproductive life histories of the native (protandrous hermaphrodite) and the introduced (dioecious) bivalves. These results suggest that positive interactions among the hundreds of introduced species that are accumulating in coastal systems could result in the rapid transformation of previously benign introductions into aggressively expanding invasions. Even if future management efforts reduce the number of new introductions, given the large number of species already present, there is a high potential for positive interactions to produce many future management problems. Given that invasional meltdown is now being documented in natural systems, I suggest that coastal systems may be closer to this threshold than currently believed.
Climate change and biological invasions are primary threats to global biodiversity that may interact in the future. To date, the hypothesis that climate change will favour non‐native species has been ...examined exclusively through local comparisons of single or few species. Here, we take a meta‐analytical approach to broadly evaluate whether non‐native species are poised to respond more positively than native species to future climatic conditions. We compiled a database of studies in aquatic and terrestrial ecosystems that reported performance measures of non‐native (157 species) and co‐occurring native species (204 species) under different temperature, CO2 and precipitation conditions. Our analyses revealed that in terrestrial (primarily plant) systems, native and non‐native species responded similarly to environmental changes. By contrast, in aquatic (primarily animal) systems, increases in temperature and CO2 largely inhibited native species. There was a general trend towards stronger responses among non‐native species, including enhanced positive responses to more favourable conditions and stronger negative responses to less favourable conditions. As climate change proceeds, aquatic systems may be particularly vulnerable to invasion. Across systems, there could be a higher risk of invasion at sites becoming more climatically hospitable, whereas sites shifting towards harsher conditions may become more resistant to invasions.
Biotic resistance in marine environments Kimbro, David L; Cheng, Brian S; Grosholz, Edwin D ...
Ecology letters,
June 2013, Letnik:
16, Številka:
6
Journal Article
Recenzirano
Biological invasions depend in part on the resistance of native communities. Meta‐analyses of terrestrial experiments demonstrate that native primary producers and herbivores generally resist ...invasions of primary producers, and that resistance through competition strengthens with native producer diversity. To test the generality of these findings, we conducted a meta‐analysis of marine experiments. We found that native marine producers generally failed to resist producer invasions through competition unless the native community was diverse, and this diversity effect was weaker in marine than in terrestrial systems. In contrast, native consumers equally resisted invasive producers in both ecosystems. Most marine experiments, however, tested invasive consumers and these invasions were resisted more strongly than were producer invasions. Given these differences between ecosystems and between marine trophic levels, we used a model‐selection approach to assess if factors other than the resistance mechanism (i.e. competition vs. consumption) are more important for predicting marine biotic resistance. These results suggest that understanding marine biotic resistance depends on latitude, habitat and invader taxon, in addition to distinguishing between competition with and consumption by native species. By examining biotic resistance within and across ecosystems, our work provides a more complete understanding of the factors that underlie biological invasions.
Conservation aquaculture is becoming an important tool to support the recovery of declining marine species and meet human needs. However, this tool comes with risks as well as rewards, which must be ...assessed to guide aquaculture activities and recovery efforts. Olympia oysters (Ostrea lurida) provide key ecosystem functions and services along the west coast of North America, but populations have declined to the point of local extinction in some estuaries. Here, we present a species-level, range-wide approach to strategically planning the use of aquaculture to promote recovery of Olympia oysters. We identified 12 benefits of culturing Olympia oysters, including identifying climate-resilient phenotypes that add diversity to growers' portfolios. We also identified 11 key risks, including potential negative ecological and genetic consequences associated with the transfer of hatchery-raised oysters into wild populations. Informed by these trade-offs, we identified ten priority estuaries where aquaculture is most likely to benefit Olympia oyster recovery. The two highest scoring estuaries have isolated populations with extreme recruitment limitation-issues that can be addressed via aquaculture if hatchery capacity is expanded in priority areas. By integrating social criteria, we evaluated which project types would likely meet the goals of local stakeholders in each estuary. Community restoration was most broadly suited to the priority areas, with limited commercial aquaculture and no current community harvest of the species, although this is a future stakeholder goal. The framework we developed to evaluate aquaculture as a tool to support species recovery is transferable to other systems and species globally; we provide a guide to prioritizing local knowledge and developing recommendations for implementation by using transparent criteria. Our collaborative process engaging diverse stakeholders including managers, scientists, Indigenous Tribal representatives, and shellfish growers can be used elsewhere to seek win-win opportunities to expand conservation aquaculture where benefits are maximized for both people and imperiled species.
Many non-native plants in the US have become problematic invaders of native and managed ecosystems, but a new generation of invasive species may be at our doorstep. Here, we review trends in the ...horticultural trade and invasion patterns of previously introduced species and show that novel species introductions from emerging horticultural trade partners are likely to rapidly increase invasion risk. At the same time, climate change and water restrictions are increasing demand for new types of species adapted to warm and dry environments. This confluence of forces could expose the US to a range of new invasive species, including many from tropical and semiarid Africa as well as the Middle East. Risk assessment strategies have proven successful elsewhere at identifying and preventing invasions, although some modifications are needed to address emerging threats. Now is the time to implement horticulture import screening measures to prevent this new wave of plant invasions.
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