Biological Invasion

One of the primary tools for raising awareness on biological invasions has been the publication of species accounts of the most prominent alien invaders. Until now such compilations have been available only for particular taxa, biomes and/or regions (Cronk and Fuller 2001; Weber 2003; Weidema 2000). In Europe, species accounts for selected invasive species have been published for a few countries or

Our ability to demonstrate statistical patterns of invasion by non-native species will determine the success of future management projects. We investigated the suitability of self-organizing maps (SOM, neural network) for patterning habitat invasion by exotic fish species at the regional scale (Southwest France), using a binary dataset of species occurrences. The SOM visualization can be used as an analytical tool to bring out relationships between sample locations and biological variables, but in addition the weight of each species in the output of the SOM can be interpreted as its occurrence probability in various geographic areas. After training the SOM with fish presence/absence data, the k-means algorithm helped to derive three major clusters of sites (headwater, montane, and plain areas). Each cluster was divided into two subsets of sites according to non-native fish, because assemblage compositions delineated different geological areas: Pyrenees Mountains, Massif Central Moun...

In this chapter, we review empirical evidence for stronger allelopathic effects of exotic European invaders on North American natives than on other European species. We argue that this evidence provides critical insights into the impor- tance of coevolutionary relationships within plant communities. We discuss how the disruption of these and other biochemical coevolutionary relation- ships may lead to the success

Background: The invasion by Pinus elliottii is one of the most serious threats to the remaining native cerrado vegetation in São Paulo State, Brazil, causing biodiversity losses yet to be evaluated. We conducted a study in an area where P. elliottii began establishing in 1988. Aims: To estimate diversity losses in the plant community and to understand the floristic and structural changes resulting from pine tree invasion of grassland savannah. Methods: All plants taller than 50 cm were sampled in 35 plots (64 m2 each) within an area densely invaded by P. elliottii and in 10 plots in non-invaded grassland savannah. Density, species richness, diversity, ground cover and spatial distribution were compared by Wilcoxon tests, non-metric multidimensional scaling and Payandeh indices. Results: Twenty-two years after the arrival of the first invasive trees (founders), the grassland savannah has become a dense pine forest with 12,455 individuals ha−1, a basal area of 26.44 m2 ha−1, a sparse native woody understory comprised of 16 species (H' = 0.44), density of 1210 individuals ha−1 and the herbaceous layer totally absent. Conclusions: Invasion by Pinus elliottii has completely changed the structure of the grassland savannah and caused severe plant diversity losses. Native species surviving the invasion in the understory do not typically represent the previous composition and functional traits of the native vegetation.

Feral cat Felis catus predation on seabirds has been well documented; however, details regarding shifts in feral cat diet in relation to seabird availability, seabird predation rate and impact on seabird population dynamics are scarce. Here, we present data documenting a seasonal shift in feral cat diet at Juan de Nova Island, Mozambique Channel. We also quantify sooty tern Sterna fuscata predation by feral cats and examine the impact on sooty terns over both the short term (by removing individual cats from sub-colonies) and over the longer term by highlighting their influence on population growth rate (λ) using a deterministic matrix model. Cat diet shifted dramatically from insects, rats and mice outside the tern breeding season to primarily terns when terns were breeding. The predation rate of sooty terns at Juan de Nova was estimated at 5.94 terns cat−1 day−1, with a proportion of these (22%) being killed without being consumed (‘surplus kills’). When only one cat was removed from each sub-colony, tern predation declined tenfold in the short term. From our matrix model, the annual growth rate for sooty terns was 1.01 in the absence of cat predation. It remained above one until a predation impact equivalent to approximately three times the estimated cat density (12.04 per km2) was incorporated. Our results demonstrate that cats preferentially predate and have an impact on breeding sooty terns at Juan de Nova, and that an increase in cat density could lead to negative effects on population growth, despite the large breeding tern population.

The paper provides an analysis of the spread of the alien prickly pear cactus (Opuntia ficus-indica) through the Eastern divisions of the Cape Colony in the latter half of the nineteenth century. It argues that biological invasions are historical processes whose trajectories are crucially shaped by the diverse and shifting cultural values attached to the invader by the invaded human society. Prickly pear underwent a gradual transformation from utility to weed as it traversed space (west to east) and time (seventeenth to nineteenth centuries), entering new natural (Karoo for Mediterranean) and economic (market for subsistence) environments more conducive to its rapid spread. Even then its definition as ‘evil’ reflected class and regional biases not shared by either the rural poor of the Eastern Cape (whether black and white) or commercial stock farmers above and west of the Winterberg–Amatola line who prized and frequently cultivated the plant for subsistence and fodder. This division and widespread non-compliance blunted official extermination efforts and left the matter unresolved by the end of the colonial period. A cultural explanation of the prickly pear invasion is contrasted with both purely biological explanations and the tendency of environmental historians to reduce such events to environmental epiphenomenon of capitalism.

Scholars studying the globalization of Australian trees have previously emphasized the rapid natural propagation of Australian trees outside of their native habitats, believing their success to be a reversal of ‘‘ecological imperialism’’ from the ‘‘new world’’ to the ‘‘old world.’’ This article argues that the expansion of Australian trees should not be viewed as a biological phenomenon, but as the result of a long-term attempt by powerful states and state-sponsored scientists to select and breed Australian species that could grow in a variety of climates and ecological conditions. Five non- biological factors largely determined the success of these attempts to grow Australian trees: the abundance or paucity of natural forests, state power, the amount of scientific research directed to planting Australian trees, the cost of labor, and the ability to utilize hardwood timbers and bark. This paper compares the use of Australian trees in Australia, India, and South Africa to demonstrate that biology was not the determining factor in the long-term success of many Australian genera and species.

The many qualifying terms attributed to invasive species reveal the lack of precision surrounding the notion of biological invasion itself. In spite of several proposed definitions, some basic disagreements persist concerning characterization of the phenomenon. These primarily arise from the lack of pertinence of both of the main current criteria—the geographic (or biogeographic) criterion and the impact criterion—to what is really intended by “invasion.” Faced with this situation, it seems preferable to adopt an ontological approach allowing a return to the basic principles of the elaboration of a definition. Starting with the nature of the phenomenon itself (i.e., its essence), we try to elucidate the notion of biological invasion and we suggest a general definition compatible with most of the ideas already expressed.

Eradication is the complete and permanent removal of all wild populations of an alien plant or animal species from a defined area, by means of a time-limited campaign.This measure is therefore different from control, i.e. the reduction of population density and abundance in order to keep damage at an acceptable level, and containment, aimed at limiting the spread of a species by containing its presence within defined geographical boundaries (Bomford and O’Brien 1995). Following this definition, also the removal of very few individuals is an eradication, if these have the potentialities of reproducing and establishing in the wild (i.e. this does not include the removal of single animal individuals but includes removal of seeds or plant propagules in the wild, or of a few pairs of animals). Eradication of unwanted alien species is an increasingly important tool for conservation of biological diversity. In fact, although the most effective way for mitigating the impacts caused by biological invasions is the prevention of new unwanted introductions, once prevention has failed and an alien species has invaded a new area, eradication is the best alternative, considering the costs and undesired effects related to permanent control or to a “do-nothing” policy.

Invasion Biology, the study of biota redistributed via human agency, has traditionally traced its founding to Charles Elton’s 1958 book The Ecology of invasions by Animals and Plants. But there were many substantial, scientific pre-Eltonian accounts and analyses of redistributed biota dating back at least to the mid-1700s; and non-Eltonian treatments appeared into the late 1950s. Elton began writing on the topic by 1925. From 1931 to 1948 he developed his ideas on conservation in association with Aldo Leopold. Their “competitive collaboration” is explored and documented, showing that each supported and contextualized the other. Elton was, in part, inspired to write The Ecology of invasions by Animals and Plants in dissatisfied response to an earlier effort by American Marston Bates. The two authors, and these works, are compared and contrasted. The Ecology of Invasions by Animals is analyzed in detail, showing how Elton framed his arguments in terms of warfare and cold-war era nuclear alarmism, making a plea for action without providing a strong theoretical basis for preventing the redistribution of biota. The republication of Elton’s book in 2000 iincited a new round of interpretation, but even while its proponents hailed the book as invasion biology’s ‘bible,’ they prepared to replace it with more modern texts. The narrative shows how a ideas about the origins of life on earth, the role of humans in nature, a sense of place and biogeographical belonging, and concerns about the unintended consequences of human agency motivated scientists to attempt to impute order to, and impose it upon, the historically contingent distribution of biota.

Decision makers and researchers recognize the need to effectively confront the social dimensions
and conflicts inherent to invasive species research and management. Yet, despite numerous contentious situations that have arisen, no systematic evaluation of the literature has examined the commonalities in the patterns and types of these emergent social issues. Using social and ecological keywords, we reviewed trends in the social dimensions of invasive species research and management and the sources and potential solutions to problems and conflicts that arise around invasive species. We integrated components of cognitive hierarchy theory and risk perceptions theory to provide a conceptual framework to identify, distinguish, and provide understanding of the driving factors underlying disputes associated with invasive species. In the ISI Web of Science database, we found 15,915 peer-reviewed publications on biological invasions, 124 of
which included social dimensions of this phenomenon. Of these 124, 28 studies described specific contentious situations. Social approaches to biological invasions have emerged largely in the last decade and have focused on both environmental social sciences and resource management. Despite being distributed in a range of journals, these 124 articles were concentrated mostly in ecology and conservation-oriented outlets. We found that conflicts surrounding invasive species arose based largely on differences in value systems and to a lesser extent stakeholder and decision maker’s risk perceptions. To confront or avoid such situations, we suggest integrating the plurality of environmental values into invasive species research and management via
structured decision making techniques, which enhance effective risk communication that promotes trust and confidence between stakeholders and decision makers.

ABSTRAK
Interaksi trofik pasca masuknya ikan introduksi ataupun ikan asing invasif merupakan dasar
untuk mengkaji tekanan ekologis terhadap ikan asli. Penelitian ini bertujuan untuk menganalisis interaksi trofik komunitas ikan pasca berkembangnya jenis-jenis ikan asing invasif di Danau Matano, Sulawesi Selatan. Ikan contoh diperoleh dari hasil tangkapan jaring insang percobaan, jala lempar, dan seser pada Mei, Oktober, dan November 2015 serta Februari, Juli, dan September 2016. Analisis ekologi trofik yang dilakukan meliputi indeks bagian terbesar, tingkat trofik, luas relung dan tumpang tindih relung makanan, serta pola strategi makan. Hasil penelitian menunjukkan komunitas ikan yang tertangkap di Danau Matano terdiri atas 9 famili, 11 genera, dan 17 spesies. Ikan louhan mendominasi komunitas ikan di Danau Matano sebesar 53,62%. Makanan alami yang banyak dimanfaatkan oleh sejumlah ikan dalam komunitas adalah insekta (Diptera), Gastropoda (Tylomelania sp.), dan larva insekta (Chironomidae). Kelompok trofik komunitas ikan di Danau Matano terdiri atas detritivora, herbivora, insektivora, zoobentivora, dan
piscivora. Masuknya ikan introduksi memunculkan kelompok trofik baru (detritivora dan herbivora). Ikan introduksi cenderung memiliki luas relung makanan yang lebih bervariasi. Kompetisi terhadap makanan alami kategori moderat banyak terjadi antara ikan asli dengan louhan. Strategi pola makan ikan asli di Danau Matano cenderung bersifat spesialis, sedangkan ikan introduksi memiliki strategi pola makan yang lebih bervariasi dan oportunistik. Ikan louhan sebagai ikan introduksi dominan yang bersifat invasif mampu memanfaatkan seluruh sumber daya makanan alami yang tersedia dan menempati tingkat trofik tertinggi di Danau Matano. Tekanan ekologi terhadap ikan asli oleh ikan asing invasif di Danau Matano terjadi karena adanya kompetisi terhadap makanan alami.

Kata Kunci: Danau Matano; ikan asing invasif; ikan louhan; interaksi trofik; strategi pola makan

ABSTRACT
Trophic interactions post-develpment of non-native fish or invasive alien fish species are the basis knowledge for assessing and preventing the ecological pressure on native fish. This research aims to analyze the trophic interactions of fish community post-development of invasive alien fish species in Lake Matano, South Sulawesi. Fish samples were obtained from the catch of experimental gill nets, cast nets, and push nets in May, October, and November 2015 along with February, July, and September 2016. Trophic ecological analysis carried out included index of preponderance, trophic level, niche breadth and niche overlap of natural food, and feeding strategy. The fish
community caught in Lake Matano consists of 9 families, 11 genera, and 17 species. Flowerhorn cichlid dominates the fish community in Lake Matano by 53.62%. Natural foods that are widely used by a number of fish in the community are Insecta (Diptera), Gastropods (Tylomelania sp.), and larvae of Insecta (Chironomidae). The guild trophic of fish community in Lake Matano consists of detritivores, herbivores, insectivores, zoobentivores, and piscivores. The introduction of non-native species bring up to new guilds (detritivores and herbivores). Non-native fishes tends to have a variety niche breadth. Moderate competition for natural food resources between native fish and flowerhorn cichlid is quite high. Feeding strategy of native species in Lake Matano tend to be specialist, while non-natives species have more variety and opportunistic. Flowerhorn cichlid as dominant invasive alien fish species is able to utilize all natural food resources and occupies the highest trophic level in Lake Matano. Ecological pressure on native fish by invasive alien fish species in Lake Matano occurs due to competition in obtaining natural food resources.

Keywords: Lake Matano; invasive alien species; flowerhorn cichlid; trophic interactions; feeding strategy

The most widespread invasive alien plant species in South Africa’s Kruger National Park (KNP) were either introduced unintentionally along rivers and roads, or intentionally for use as ornamentals. We examine the spatial distribution of ornamental alien plants in KNP, look at the link between human population size, history, and species richness, and show how the distribution of particular species reflects the likely history of ornamental plantings. Results are used to assess whether past management actions have been appropriately directed. Two hundred and fifty-eight alien species have been recorded in the 36 tourist camps and staff villages. The number of staff housed in villages explains much of the diversity of cultivated alien plant species. Older camps also tend to have more ornamental alien plant species. However, the lack of a strong link between camp age and number of cultivated species suggests that ornamental plants have been widely spread around the KNP by humans. We also show that increased camp activity (either size or age) has led to more ornamental species, while, with the notable exception of Skukuza, camp activity has had a much smaller effect on the number of noncultivated species. Noncultivated species tend to be naturally dispersed, as opposed to directly spread by humans between camps. Past management prioritized certain species on the basis of their potential to invade KNP and on the prevailing national legislation. These species were removed manually and follow-up control was carried out. Once the priority species were deemed to be under control, less invasive species were targeted. All alien species were removed from vacated houses, regardless of the potential invasiveness of the species.

This article explains how South African foresters have selected, experimented with and successfully grown Australian genera and species of trees in plantations during the past 130 years. First in the Cape Colony in the 1880s and 1890s, and later elsewhere in South Africa in the twentieth century, foresters developed theoretical techniques to find climates similar to those in southern Africa in order to select exotic species of trees from those regions. They then tested these species in experimental arboreta and plantations across South Africa to select the most successful and valuable species to grow commercially in each area. This globally unique and ultimately successful research programme arose in response to local environmental constraints, an increasing demand for timber, and the difficulties that foresters and white settlers faced when trying to select and grow Australian trees. This article revises historical understandings of the development of silviculture in South Africa and intervenes in current scientific and popular debates over Australian trees in South Africa.

The Korean freshwater crayfish, Cambaroides similis, has recently suffered from range reduction and habitat degradation caused by environmental changes and water pollution. For the conservation and restoration of this species, it is necessary to understand the current population structures of Korean C. similis using estimation of their genetic variation. In this study, eight microsatellite loci were developed and characterized from 49 individuals collected from four locations: one population from Mt. Bukhan (BH) and three populations from Mt. Gwanak (GA) in Seoul, Korea. As a result, the number of alleles per locus ranged from 2 to 12. The observed heterozygosities and expected heterozygosities ranged from 0.000 to 0.833 and from 0.125 to 0.943, respectively, and the former values were significantly lower than the latter ones expected under the Hardy-Weinberg equilibrium. No significant linkage disequilibrium was revealed between any of the locus pairs after Bonferroni correction. From the pairwise Fst results over all samples, higher differentiation between GA-BH population pairs (mean 0.1789) was observed than between GA population pairs (mean 0.0454). This was also supported by Mantel's test showing that the genetic distances of these crayfish populations were significantly correlated with geographic distances. This result may show the regional differentiation caused by restricted gene flow between northern (BH) and southern (GA) populations within Seoul. These microsatellite markers have the potential for use in analyses of the genetic diversity and population structure of C. similis species, with implications for its conservation and management plans.