225 research outputs found
Shared Histories of Co-evolution May Affect Trophic Interactions in a Freshwater Community Dominated by Alien Species
Interactions occurring between species in multiple invaded freshwater ecosystems are often difficult to observe and study. Studies on invasive alien species typically focus on single species, and, when the species community is exclusively composed of alien species, their interactions, eventual facilitation and hindering processes are very scarcely assessed. To investigate such a community, the species community in the Arno River (Tuscany, Italy) was examined as a model system using the combined approach of stable isotopes and dietary analyses. Established alien species have formed a pyramid shaped community with the European catfish Silurus glanis and the North American channel catfish Ictalurus punctatus in the apex position, followed by opportunistic predatory (Lepomis gibbosus) and omnivore (Alburnus alburnus, Cyprinus carpio, Barbus barbus, Pseudorasbora parva, Padogobius sp., Tinca tinca) species. These species were observed to feed on a variety of primary producers (Myriophyllum sp., Potamogeton sp., Phragmites australis) and consumers (aquatic insects, molluscs, Dikerogammarus villosus, Procambarus clarkii, Palaemon antennarius, tadpoles). Remarkably, the channel catfish Ictalurus punctatus showed an ontogenetic niche shift, with juveniles occupying a slightly higher trophic position than mature individuals. Pseudorasbora parva and A. alburnus showed a strong niche overlap, with the former having a wider niche. Such wide niches were also found for the invasive crustaceans D. villosus and P. clarkii. Outgoing from our findings, we suggest that life-history and geographic origin play a role in determining competition and interaction type among alien species, with species from the same geographic area showing a lower potential to compete than species from different areas, hence affecting their potential impact on native species
Is the number of non-native species in the European Union saturating?
Background
Non-native species can have significant negative impacts on the environment, economies, and amongst others, also human Non-native species can have significant negative impacts on the environment, economies, and human Non-native species can have significant negative impacts on the environment, economies, and human well-being, among other factors. Globalisation and economic incentives have substantially facilitated the growth in the numbers of newly recorded non-native species in the European Union. The European Unionâs diversity in terms of political and socio-economic differences across member states may have contributed to the introduction of non-native species.
Results
Data reported in the Alien Species First Record Database, however, suggests a decreasing trend in the number of non-native species recorded over the past three decades. InvaCost, a database of non-native species with economic impacts, similarly shows increasing numbers of reported non-native species with costs until the 2010s, which were, however, followed by a plateauing and ultimately decline. Although the recent trends in non-native species reports may be affected by a lag time in reporting and data allocation as well as possibly a disparity in research efforts, their impacts persist, leading to a growing ecological but also economic burden. We further identified substantial spatial differences as western European member states generally reported higher numbers of non-native species and non-native species with monetary impacts.
Conclusions
Without improved actions, biological invasions and their associated impacts will continue to rise, degrading natural capital and hampering sustainable development and sustainability targets. Therefore, improved coordinated efforts across the European Union are necessary to improve reporting of non-native species and a centralized collation of data through accessible databases should be considered
Are the â100 of the worldâs worstâ invasive species also the costliest?
Biological invasions are increasing worldwide, damaging ecosystems and socioeconomic sectors. Two decades ago, the â100 of the worldâs worstâ invasive alien species list was established by the IUCN to improve communications , identifying particularly damaging âflagshipâ invaders globally (hereafter, worst). Whilst this list has bolstered invader awareness, whether worst species are especially economically damaging and how they compare to other invaders (hereafter, other) remain unknown. Here, we quantify invasion costs using the most comprehensive global database compiling them (InvaCost). We compare these costs between worst and other species against sectorial, taxonomic and regional descriptors, and examine temporal cost trends. Only 60 of the 100 worst species had invasion costs considered as highly reliable and actually observed estimates (median: US 0.53 million), although some other species had higher costs than most worst species. Damages to the environment from the worst species dominated, whereas other species largely impacted agriculture. Disproportionately highest worst species costs were incurred in North America, whilst costs were more evenly distributed for other species; animal invasions were always costliest. Proportional management expenditures were low for the other species, and surprisingly, over twice as low for the worst species. Temporally, costs increased more for the worst than other taxa; however, management spending has remained very low for both groups. Nonetheless, since 40 species had no robust and/or reported costs, the âtrueâ cost of âsome of the worldâs worstâ 100 invasive species still remains unknown
Primarily neutral effects of river restoration on macroinvertebrates, macrophytes, and fishes after a decade of monitoring
Restoring river habitat heterogeneity is expensive and time consuming, yet often has little effect on aquatic biota. Such poor restoration outcomes could be partly caused by the predominance of shortâterm studies, which do not account for natural temporal fluctuations nor changes in the effects of restoration through time. Consequently, research that examines the longerâterm dynamics of river restoration is crucial for providing a temporal perspective of restoration outcomes and for informing the effectiveness of restoration methods. We used the Nidda River in Germany as a case study of the temporal effects of river hydromorphological restoration on different aquatic taxa. We surveyed macroinvertebrate, macrophyte, and fish communities across three sites prerestoration (2008) and then monitored changes in one control versus two restored sites across 10âyears (2010â2019). Overall, we found few effects of restoration on the macroinvertebrate and macrophyte communities, with no effects whatsoever on fishes. Restoration improved some components of the macroinvertebrate and macrophyte communities; however, these positive effects were temporally inconsistent and did not translate to improvements in river ecosystem health (based on an index of ecological quality). Our findings illustrate how allowing for more time for community development will not necessarily alter the fact that localâscale river habitat restoration can elicit little to no change in aquatic communities. Combining localâ with broadâscale restoration efforts that address the primary drivers of hydroecological decline, in addition to longâterm monitoring, may therefore be required to ensure that river restorations successfully meet their ecological goals
Burrowing activity of Procambarus clarkii on levees: analysing behaviour and burrow structure
Modelling the damage costs of invasive alien species
The rate of biological invasions is growing unprecedentedly, threatening ecological and socioeconomic systems worldwide. Quantitative understandings of invasion temporal trajectories are essential to discern current and future economic impacts of invaders, and then to inform future management strategies. Here, we examine the temporal trends of cumulative invasion costs by developing and testing a novel mathematical model with a population dynamical approach based on logistic growth. This model characterises temporal cost developments into four curve types (IâIV), each with distinct mathematical and qualitative properties, allowing for the parameterization of maximum cumulative costs, carrying capacities and growth rates. We test our model using damage cost data for eight genera (Rattus, Aedes, Canis, Oryctolagus, Sturnus, Ceratitis, Sus and Lymantria) extracted from the InvaCost databaseâwhich is the most up-to-date and comprehensive global compilation of economic cost estimates associated with invasive alien species. We find fundamental differences in the temporal dynamics of damage costs among genera, indicating they depend on invasion duration, species ecology and impacted sectors of economic activity. The fitted cost curves indicate a lack of broadscale support for saturation between invader density and impact, including for Canis, Oryctolagus and Lymantria, whereby costs continue to increase with no sign of saturation. For other taxa, predicted saturations may arise from data availability issues resulting from an underreporting of costs in many invaded regions. Overall, this population dynamical approach can produce cost trajectories for additional existing and emerging species, and can estimate the ecological parameters governing the linkage between population dynamics and cost dynamics
Global economic costs of herpetofauna invasions
Biological invasions by amphibian and reptile species (i.e. herpetofauna) are numerous and widespread, having caused severe impacts on ecosystems, the economy and human health. However, there remains no synthesised assessment of the economic costs of these invasions. Therefore, using the most comprehensive database on the economic costs of invasive alien species worldwide (InvaCost), we analyse the costs caused by invasive alien herpetofauna according to taxonomic, geographic, sectoral and temporal dimensions, as well as the types of these costs. The cost of invasive herpetofauna totaled at 17.0 billion US for amphibians, 10.4 billion US for mixed classes. However, these costs were associated predominantly with only two species (brown tree snake Boiga irregularis and American bullfrog Lithobates catesbeianus), with 10.3 and 6.0 billion US$ in costs, respectively. Costs for the remaining 19 reported species were relatively minor (â99%), while for reptiles, impacts were reported mostly through damages to mixed sectors (65%). Geographically, Oceania and Pacific Islands recorded 63% of total costs, followed by Europe (35%) and North America (2%). Cost reports have generally increased over time but peaked between 2011 and 2015 for amphibians and 2006 to 2010 for reptiles. A greater effort in studying the costs of invasive herpetofauna is necessary for a more complete understanding of invasion impacts of these species. We emphasise the need for greater control and prevention policies concerning the spread of current and future invasive herpetofauna.info:eu-repo/semantics/publishedVersio
Resolving the issues of translocated species in freshwater invasions
Biological invasions, driven by human-mediated species movements, pose significant threats to global ecosystems and economies. The classification of non-native species is a complex issue intertwining ecological considerations and ethical concerns. The need for nuanced and less ambiguous terminology is emphasised, considering biogeographic, evolutionary, and ecological principles. In-country translocations of native species into ecosystems in which they do not naturally occur, are often overlooked and are the least regulated among species movements, despite being increasingly common in conservation. Our case studies, spanning various ecosystems and taxa, illustrate the diverse impacts of translocations on native species and ecosystems. The challenges associated with translocated species underscore the urgency for robust risk management strategies and rigorous monitoring. A comprehensive and adaptable management framework that considers translocated species for evidence-based management decisions is critical for navigating the complexities of translocations effectively, ensuring the conservation of biodiversity and ecosystem sustainability
THE EFFECTS OF TWO DIFFERENT PRESERVATION METHODS ON MORPHOLOGICAL CHARACTERISTICS OF THE ALIEN CHANNEL CATFISH Ictalurus punctatus (Rafinesque, 1818) IN EUROPEAN FRESHWATER
RazliÄite metode koje se koriste za pohranu uzoraka, Äak i u kraÄim vremenskim razmacima, mogu uvelike utjecati na morfometrijske osobitosti kao ĆĄto su boja, duljina i oblik uzorka. Kao posljedica, u sluÄaju da uzorci moraju biti analizirani morfometrijski, odabir odgovarajuÄemetode konzervacije/oÄuvanja uzorka je kljuÄna. U ovom istraĆŸivanju su usporeÄeni uÄinci, dvije podjednako lako primjenjive metode oÄuvanja, smrzavanja i umjereno svjeĆŸeg skladiĆĄtenja na morfoloĆĄka obiljeĆŸja sjevernoameriÄkog kanalskog soma Ictalurus punctatus, kao strane vrste prisutne u Europskim kopnenim vodama. Rezultati su ukazali da je smrzavanje, kao i konzervacija alkoholom ili formalinom, utjecalo na opÄenite karakteristike uzorka (boja, standardna, ukupna i duljina ribe do vilice te oblik), dok je umjereno svjeĆŸe skladiĆĄtenje indiciralo oÄuvanje veÄine osobina uzorka bez istaknutih promjena, ĆĄto je vaĆŸna razlika pri prouÄavanju potencijalno prilagodljivih stranih vrsta riba. U radu su razmatrane implikacije.Different methods used to store specimens, even for short periods, can notably affect morphometric characteristics such as colour, length and shape. As a consequence, in the case of samples that have to be analysed morphometrically, the right reservation method is crucial. In this study, two comparably easy applicable methods, the effects of freezing and moderate cool storage on morphological traits, were studied on specimens of the scaleless North American channel catfish Ictalurus punctatus, an alien species to European freshwaters of increasing concern. Results revealedthat freezing, like preservation with alcohol or formalin, affected the generally considered characteristics (colour, standard length, fork length, total length, shape), while cool storage was shown to preserve most traits without notable alteration, an important difference when studying potentially adapting alien species. Implications are discussed
Intercontinental invasion dynamics of Cercopagis pengoi, an IUCN-listed planktonic invasive species
Predicting the spread of invasive species and understanding the role of niche dynamics in niche transferability are critical challenges in the management of biological invasions, both theoretically and practically. We used complementary species distribution modelling approaches, such as multivariate niche analysis and reciprocal distribution models, to test the niche conservatism hypothesis and to predict the potential distribution of the fishhook waterflea, Cercopagis pengoi. Our analysis indicated a significant similarity between its native and invasive ranges, suggesting that a subset of the Ponto-Caspian propagules may have been the founders of European populations. However, our results contradict the niche conservatism hypothesis, showing that C. pengoi has not fully occupied the available niche within its current invasive ranges. Moreover, we observed a notable niche expansion, reflecting a significant shift in niche following its intercontinental introduction in North America. Given the suitability of new environments for the expansion of C. pengoi and its tendency to evade detection prior to population surges, we recommend a focus on early detection through monitoring of both water columns and bottom sediments. This should be complemented by strict enforcement of ballast water regulations to curtail its spread in North America, Europe, and other suitable non-native regions globally
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