Widespread Alien Species Research Articles

Three days at school with FAST

“Three days at school with FAST” is the name of the environmental education project included within the FAST (Fight Alien Species Transborder), Project Interreg Italy-Malta. The FAST Project aims to record the entry and spread of non-native animal and plant species; and even more so those invasive species capable of reducing biodiversity in the islands of Sicily and Malta, located in the center of the Mediterranean basin. Furthermore, an important part of the project concerns dissemination, raising awareness among the community about alien species, the problems associated with them and the protection of biodiversity. Environmental education in schools (today considered an important form of dissemination of good practices) is the focus of the three days at school with FAST. An attempt was made to give the youngest elementary and middle school students tangible experiences, to teach them useful practices for the protection of nature by explaining, for the purposes of greater knowledge and awareness, environmental issues and problems linked to the most well-known and widespread alien species in Sicily, Thanks to the game and the experiences proposed in the three scheduled meetings, the aim is to enhance and at the same time learn to protect local environmental resources.

Rare, common, alien and native species follow different rules in an understory plant community.

Biological invasions are a leading threat to biodiversity globally. Increasingly, ecosystems experience multiple introductions, which can have significant effects on patterns of diversity. The way these communities assemble will depend partly on whether rare and common alien species respond to environmental predictors in the same manner as rare and common native species, but this is not well understood. To examine this question across four national parks in south‐eastern Australia, we sampled the understory plant community of eucalypt‐dominated dry forest subject to multiple plant introductions. The drivers of diversity and turnover in alien and native species of contrasting frequency of occurrence (low, intermediate, and high) were each tested individually. We found alien species diversity and turnover were both strongly associated with abiotic conditions (e.g., soil pH), while distance had little influence because of the greater extent of occurrence and more homogeneous composition of common aliens. In contrast, native species diversity was not associated with abiotic conditions and their turnover was as strongly influenced by distance as by abiotic conditions. In both alien and native species, however, the most important predictors of turnover changed with frequency of occurrence. Although local coexistence appears to be facilitated by life history trade‐offs, species richness of aliens and natives was negatively correlated and native species might face greater competition in areas with more neutral soils (e.g., pH > ~5.5) where alien richness and relative frequency were both highest. We conclude that diversity and turnover in the generally more widespread alien species are mainly driven by species sorting along an environmental gradient associated with pH and nutrient availability, whereas turnover of native species is driven by more neutral processes associated with dispersal limitation. We show alien and native plant species respond to different environmental factors, as do rare and common species within each component.

Τhe fish fauna in lentic ecosystems of Greece

This study provides an annotated checklist of the freshwater fish species recorded in lentic ecosystems of Greece. Species distributional data were derived from an extensive review of published and unpublished sources and were evaluated for their consistency, adequacy and reliability. Overall, 650 freshwater lentic ecosystems (149 natural and 501 artificial) were investigated from which, 480 were fishless or fish data were unavailable. In the remaining 170 ecosystems, 122 taxa were recorded (belonging to 22 families and 57 genera). Some of the records concerned species with extirpated populations, species of doubtful occurrences and taxa of uncertain taxonomic status. The highest species richness (52 species) was recorded in the Ionian ecoregion while endemicity was highest in the Macedonia-Thessaly ecoregion (43.75%). The Eastern Aegean ecoregion presented the highest level of introduced species (75%). Only eight ecosystems hosted 20 or more species, while 92 ecosystems had over 50% of introduced species. The most widespread native species (Anguilla anguilla and Luciobarbus albanicus) were two highly migratory species, highlighting the importance of connectivity of aquatic ecosystems. The most widespread translocated species was Cyprinus carpio due its high commercial and recreational value, whereas Gambusia holbrooki confirmed its high dispersal ability being the most widespread alien species. More than one third of the species recorded (37.23 %) are threatened based on the IUCN Red List. The ultimate contribution of this study is to support the coordination and dissemination of baseline information on the freshwater fishes of Greek lentic ecosystems, required by a range of users. This knowledge will enable further understanding of the regional assemblage structure and other biogeographical patterns of the ichthyofauna of Greece and will contribute to species conservation by prioritising areas hosting species in need of protection. Finally, this study reveals the high knowledge gap regarding species composition in many Greek lentic ecosystems and highlights the need for relevant primary research including more systematic and standardised samplings.

Litter in alien species of possible commercial interest: The blue crab (Callinectes sapidus Rathbun, 1896) as case study

Marine litter levels were measured in the stomach contents, hepatopancreas, and gonad tissues of crustacea decapod (Callinectes sapidus Rathbun, 1896; n = 6), a widespread alien species affecting the Lesina lagoon. Results highlight a mean of 2.5 (SD = 1.6) items/animal and indicate the presence of metals fragments (13%) and plastics (13% PE; 6.7% PET) in the stomach contents of collected individuals. No microplastic particles were detected in the hepatopancreas or in muscle tissue, while microplastic fibres (nylon, rayon, polyester) were found present in female specimen gonads. The presence of synthetic fibres in the investigated species reflects the relative contamination level in this habitat type and suggests that the blue crab could be considered a model organism for evaluating the contamination status of the study area.

Invasive species differ in key functional traits from native and non‐invasive alien plant species

AbstractQuestionsInvasive species establish either by possessing traits, or trait trade‐offs similar to native species, suggesting pre‐adaptation to local conditions; or by having a different suite of traits and trait trade‐offs, which allow them to occupy unfilled niches. The trait differences between invasives and non‐invasives can inform on which traits confer invasibility. Here, we ask: (a) are invasive species functionally different or similar to native species? (b) which traits of invasives differ from traits of non‐invasive aliens and thus confer invasibility? and (c) do results from the sub‐Antarctic region, where this study was conducted, differ from findings from other regions?LocationSub‐Antarctic Marion Island.MethodsWe measured 13 traits of all terrestrial native, invasive and non‐invasive alien plant species. Using principal components analysis and phylogenetic generalized least‐squares models, we tested for differences in traits between invasive (widespread alien species) and native species. Bivariate trait relationships between invasive and native species were compared using standardized major axis regressions to test for differences in trait trade‐offs between the two groups. Second, using the same methods, we compared the traits of invasive species to non‐invasive aliens (alien species that have not spread).ResultsBetween invasive and native species, most traits differed, suggesting that the success of invasive species is mediated by being functionally different to native species. Additionally, most bivariate trait relationships differed either in terms of theiry‐intercept or their position on the axes, highlighting that plants are positioned differently along a spectrum of shared trait trade‐offs. Compared to non‐invasive aliens, invasive species had lower plant height, smaller leaf area, lower frost tolerance, and higher specific leaf area, suggesting that these traits are associated with invasiveness. The findings for the sub‐Antarctic corresponded to those of other regions, except lower plant height which provides a competitive advantage to invaders in the windy sub‐Antarctic context.ConclusionOur findings support the expectation that trait complexes of invasive species are predominantly different to those of coexisting native species, and that high resource acquisition and low defence investment are characteristic of invasive plant species.

Drivers of species turnover vary with species commonness for native and alien plants with different residence times.

Communities comprising alien species with different residence times are natural experiments allowing the assessment of drivers of community assembly over time. Stochastic processes (such as dispersal and fluctuating environments) should be the dominant factors structuring communities of exotic species with short residence times. In contrast, communities should become more similar, or systematically diverge, if they contain exotics with increasing resident times, due to the increasing importance of deterministic processes (such as environmental filtering). We use zeta diversity (the number of species shared by multiple assemblages) to explore the relationship between the turnover of native species and two categories of alien species with different residence times (archaeophytes [introduced between 4000 BC and 1500 AD] and neophytes [introduced after 1500 AD]) in a network of nature reserves in central Europe. By considering multiple assemblages simultaneously, zeta diversity allows us to determine the contribution of rare and widespread species to turnover. Specifically, we explore the relative effects of assembly processes representing isolation by distance, environmental filtering, and environmental stochasticity (fluctuating environments) on zeta diversity using Multi-Site Generalized Dissimilarity Modelling (MS-GDM). Four clusters of results emerged. First, stochastic processes for structuring plant assemblages decreased in importance with increasing residence time. Environmental stochasticity only affected species composition for neophytes, offering possibilities to predict the spread debt of recent invasions. Second, native species turnover was well explained by environmental filtering and isolation by distance, although these factors did not explain the turnover of archaeophytes and neophytes. Third, native and alien species compositions were only correlated for rare species, whereas turnover in widespread alien species was surprisingly unrelated to the composition of widespread native species. Site-specific approaches would therefore be more appropriate for the monitoring and management of rare alien species, whereas species-specific approaches would suit widespread species. Finally, the size difference of nature reserves influences not only native species richness, but also their richness-independent turnover. A network of reserves must therefore be designed and managed using a variety of approaches to enhance native diversity, while controlling alien species with different residence times and degrees of commonness.

Aphanomyces astaci presence in Japan: a threat to the endemic and endangered crayfish species Cambaroides japonicus?

Abstract Spread of the crayfish plague pathogen, Aphanomyces astaci, by North American crayfish species is considered one of the main reasons for substantial declines and local extinctions of native European crayfish populations. Owing to human introductions, several American crayfish species have become established throughout the world, and thus pose a potential threat to indigenous crayfish populations susceptible to crayfish plague. In Japan, two such widespread alien species, Procambarus clarkii and Pacifastacus leniusculus, were introduced for aquaculture purposes in the late 1920s and since then successfully expanded their ranges. Aggressive interactions with alien crayfish along with habitat modifications have been considered primarily responsible for drastic declines in populations of the Japanese endemic crayfish, Cambaroides japonicus, observed in the last few decades. However, the presence of the crayfish plague pathogen, to which Japanese crayfish are susceptible, may be expected, and could contribute to these declines. Only recently, A. astaci has been reported from Taiwan, and to our knowledge no study focusing on its presence outside of the Western Palearctic has been conducted. To fill this gap, 54 P. clarkii and 47 P. leniusculus individuals from five different Japanese locations were screened using molecular methods recommended by the World Organization for Animal Health. Aphanomyces astaci DNA was detected in all studied populations, altogether in 61% and 21% of examined individuals of P. clarkii and P. leniusculus, respectively. The results provide the first evidence of A. astaci presence in Japan and highlight the threat of pathogen transmission to C. japonicus populations. Copyright © 2016 John Wiley & Sons, Ltd.

Ecological traits of fish assemblages from Mediterranean Europe and their responses to human disturbance

Abstract Mediterranean river systems are characterised by more diverse fish assemblages and regional ecological processes compared with the rest of Europe. A data set from Mediterranean France, Iberia and Greece (∼2000 sites) was used to describe the characteristics of fish assemblages, explore their responses to anthropogenic disturbance and analyse the implications for river quality assessment. There was a southwards decline in species richness per site, but endemicity and proportion of alien species increased. Sites in the eastern Mediterranean had higher endemicity, lower site richness and lower number of alien species than sites in western Mediterranean Europe. Assemblage composition differed between Mediterranean sub‐regions, but was dominated by three major fish types: a salmonid fish type common throughout the study area and two cyprinid‐dominated fish types (in some sub‐regions, Salmo trutta L. is present but not numerically dominant), corresponding to a gradient in hydrological and temperature regimes. Metric responses to perturbation were compared with those found at the European (larger scale) and basin (smaller scale) levels. Overall metric response was weaker in this Mediterranean application. The best responses to human pressure were usually obtained with abundance‐based metrics and included the contribution of naturalised alien species. Some widespread alien species contributed to the response to anthropogenic alteration (notably Cyprinus carpio L. and Lepomis gibbosus (L.)).

Quality traits of Procambarus clarkii (girard) related to sex and refrigerated storage

The red swamp crayfish (Procambarus clarkii, Girard) is the most widespread alien species in Europe. Imported from Louisiana to southern Spain in 1973, where at present it is reared in crayfish farm and also diffused in the wild, it was introduced into Italy in the ’80s and is now well established in natural environments of northern and central Italy. Naturalization of this alien species poses risks for aquatic ecosystems and its use as food may be a way to limit its spreading. The aim of this study was to analyse the morphological, mercantile and biochemical characteristics of male and female specimens of Procambarus clarkii and to evaluate changes in qualitative traits during refrigerated storage. Specimens of red swamp crayfish collected in a river, after a rearing period of 85 days in tanks, were harvested, killed by hypothermia and refrigerated (1°C). Male (n=31) and female (n=26) specimens were separated and measured for total body and abdomen length, 1 (n=10), 3 (n=16), 8 (n=16) and 10 days (n=15) after harvesting. They were weighed, sectioned to separate claws and tails (shell-on), which were weighed individually and their colour parameters (lightness, L*; chromaticity indexes, a* and b*) measured in dorsal and ventral sites. A pooled sample consisting of tail muscle of 2-3 specimens having the same storage times was homogenized and analysed for total lipids, qualitative and quantitative fatty acid composition and malondialdehyde (MDA). The other tails (shell-on) were steamed, the exoskeleton removed and abdominal muscles (shell-off tails) analysed for colour parameters in dorsal and ventral sites, and for free water (by compression method). Data was analysed by GLM using the SAS Package, with sex, storage time and relative interaction (except for data of chemical analysis) as fixed effects. Females and males differed in total (p<0.05) and abdominal (p<0.01) length (8.65 vs 8.27cm and 4.32 vs 4.04cm, respectively) and in body weight (corrected for cheliped weight, due their lack in some cases; 16.35 vs 13.89g; p<0.05), however the cooked-meat yield of shell-on tails was similar (46.53 vs 42.93%; p=0.19). Regarding colour parameters, the two sexes only differed in L*, which was significantly greater in males in the different sites of measurement, except the ventral site of raw shell-on tails. Males and females showed a similar water holding capacity of abdominal meat (mean 10.78±6.33cm2). No differences between the sexes were recorded for total lipids (mean 1.05±0.14%), MDA content and fatty acid profile (means SFA: 22.16%, MUFA: 28.40%, PUFAn6: 20.39%; PUFAn3: 28.80%; EPA: 18.24%; DHA: 7.17%). During refrigerated storage, a significant decrease in water holding capacity of muscle (free water increasing from 14.07 to 26.15cm2 on days 1 and 10, respectively; p<0.001) and in cooked-meat yield (from 50.92 to 39.11% on days 1 and 10, respectively; p<0.01) and sharp changes in cooked tail muscle colour parameters were noticed. The latter body part showed a significant decrease (p<0.001) in a* and b* at the dorsal site and in L* at the ventral site (77.74 and 49.14 on days 1 and 10, respectively) with increasing storage. During the refrigerated storage of the whole crayfish the changes recorded for the examined parameters indicate the quality decay, particularly after the 3rd day.

The decline of native Pacific island faunas: changes in status of the land snails of Samoa through the 20th century

The highly diverse and endemic Pacific island biota is disappearing and being replaced by a relatively small number of widespread alien species. The land snail fauna of Samoa (formerly Western Samoa) contains at least 72 species (58 native, 10 alien, four cryptogenic—of unknown origin). In 1992–1994 we surveyed the fauna in order to evaluate its status and, by comparison with previous surveys, to detect any trends. Twelve species have declined (eight native, two cryptogenic); 17 (15 native, two cryptogenic) show a “probable decline” or “possible decline”; five (four alien, one native) have increased or possibly increased. Some species showed no clear trend; others could not be evaluated, but some of them may be extinct. The fauna faces threats similar to those faced elsewhere, primarily habitat destruction and alien species impacts. Most notable is the introduction of a predatory flatworm, Platydemus manokwari, in attempts to control the giant African snail, Achatina fulica, which became established in Samoa in the 1990s. The flatworm may or may not be able to control A. fulica but poses a serious threat to the native snail fauna. Further introduction and distribution of alien predators should be strongly discouraged.