Alien Plants Introduced by Different Pathways Differ in Invasion Success: Unintentional Introductions as a Threat to Natural Areas

BACKGROUND: Understanding the dimensions of pathways of introduction of alien plants is important for regulating species invasions, but how particular pathways differ in terms of post-invasion success of species they deliver has never been rigorously tested. We asked whether invasion status, distribution and habitat range of 1,007 alien plant species introduced after 1500 A.D. to the Czech Republic differ among four basic pathways of introduction recognized for plants. PRINCIPAL FINDINGS: Pathways introducing alien species deliberately as commodities (direct release into the wild; escape from cultivation) result in easier naturalization and invasion than pathways of unintentional introduction (contaminant of a commodity; stowaway arriving without association with it). The proportion of naturalized and invasive species among all introductions delivered by a particular pathway decreases with a decreasing level of direct assistance from humans associated with that pathway, from release and escape to contaminant and stowaway. However, those species that are introduced via unintentional pathways and become invasive are as widely distributed as deliberately introduced species, and those introduced as contaminants invade an even wider range of seminatural habitats. CONCLUSIONS: Pathways associated with deliberate species introductions with commodities and pathways whereby species are unintentionally introduced are contrasting modes of introductions in terms of invasion success. However, various measures of the outcome of the invasion process, in terms of species' invasion success, need to be considered to accurately evaluate the role of and threat imposed by individual pathways. By employing various measures we show that invasions by unintentionally introduced plant species need to be considered by management as seriously as those introduced by horticulture, because they invade a wide range of seminatural habitats, hence representing even a greater threat to natural areas

Climate Change, Coral Reef Ecosystems, and Management Options for Marine Protected Areas

Marine protected areas (MPAs) provide place-based management of marine ecosystems through various degrees and types of protective actions. Habitats such as coral reefs are especially susceptible to degradation resulting from climate change, as evidenced by mass bleaching events over the past two decades. Marine ecosystems are being altered by direct effects of climate change including ocean warming, ocean acidification, rising sea level, changing circulation patterns, increasing severity of storms, and changing freshwater influxes. As impacts of climate change strengthen they may exacerbate effects of existing stressors and require new or modified management approaches; MPA networks are generally accepted as an improvement over individual MPAs to address multiple threats to the marine environment. While MPA networks are considered a potentially effective management approach for conserving marine biodiversity, they should be established in conjunction with other management strategies, such as fisheries regulations and reductions of nutrients and other forms of land-based pollution. Information about interactions between climate change and more “traditional” stressors is limited. MPA managers are faced with high levels of uncertainty about likely outcomes of management actions because climate change impacts have strong interactions with existing stressors, such as land-based sources of pollution, overfishing and destructive fishing practices, invasive species, and diseases. Management options include ameliorating existing stressors, protecting potentially resilient areas, developing networks of MPAs, and integrating climate change into MPA planning, management, and evaluation

Human Dimensions of Invasive Vertebrate Species Management

Invasive vertebrate species can cause substantial damage to natural resources, property, crops, livestock, and pose a disease hazard to humans, native wildlife and domestic animals. Numerous island species have become extinct or are threatened with extinction from invasive species. The high rate of invasive species introductions continues because of the large volumes of world trade and international travel. Humans are often responsible for introductions, but are also the key to their prevention, management, and eradication. However, many of the values and perceptions of invasive species vary among humans. Hence, the prevention and control of invasive vertebrates often requires adjusting human behaviors, values, and beliefs, along with changing the way decisions are made. Most people have little idea of which species are invasive, what their impacts are, and what control methods might be appropriate for their management. A wide variety of education, outreach, and training programs are needed to help motivate people to take action and raise awareness of the causes of establishment, consequences of invasive species, and the need for prevention, control, and eradication programs. Key messages should target diverse audiences through appropriate media outlets and methods. Surveys to better understand how different stakeholder groups view invasive species, the threats they pose, and the potential methods of control are also needed. We review several programs in place to help achieve the critical need for an informed and active public with regard to invasive vertebrate species. The programs help create an informed public, generate public and financial support for invasive species management, train the public to recognize and report sightings of invasives, and encourage sustainable ecosystems

Morphological abnormality patterns in a California amphibian community

Increasing reports of amphibian limb malformations from many parts of North America have prompted investigations into the potential causes of these abnormalities and their implications for amphibian populations. Over a two-year period, we monitored the frequency and composition of morphological abnormalities in four amphibian species (Hyla regilla, Taricha torosa, Bufo boreas, and Rana catesbeiana) from two California ponds. The frequency of abnormalities differed significantly by species, life-history stage, pond, and season. Generally, the frequency and severity of abnormalities were greater in the amphibians from Frog Pond over those from Hidden Pond, and in larval stages over emerging and adult amphibians. Larvae of T. torosa exhibited the highest rate of abnormalities, ranging from 15-50%, followed by larval and metamorphic H. regilla (10-25%), and finally by metamorphic B. boreas and R. catesbeiana, both of which had rates of less than five percent. Within each species, the composition of abnormalities was strongly consistent between years, ponds, and early life-history stages. We recorded the most severe malformations in H. regilla, and more than 60% of the abnormalities in treefrogs involved extra hindlimbs, femoral projections, and skin webbings. Similarly severe, the abnormalities of R. catesbeiana were dominated by extra and missing hind- and forelimbs. In B. boreas and T. torosa, the most common morphological abnormalities were missing limbs and digits, which accounted for approximately 75% and 95%, respectively, of their total abnormalities. Potential causes of the observed abnormalities, including infection by the trematode Ribeiroia, and the conservation significance of amphibian malformations are discussed.<br /