Biological Invasions最新文献

Feral hogs (Sus scrofa) are invasive, ecosystem engineers and a novel disturbance to rare, fire-dependent, herbaceous wetland ecosystems in Florida, USA. Their feeding activity uproots vegetation, altering plant composition and continuity. Hog rooting can also create linked disturbance by ingesting vegetation critical for fire spread. Herbaceous communities are vulnerable to shrub encroachment when fire return intervals are increased. We examined the impact of hog rooting intensity (% uprooted vegetation) on the resilience of herbaceous, seepage wetland vegetation cover and composition and the effect of hog rooting on fire spread. We hypothesized that (1) vegetation cover and composition would reflect initial intensity of hog rooting and remain altered with and without additional rooting, and (2) reduction of foliar cover by feral hog rooting would reduce fire spread. Total foliar cover, functional group cover, richness, and cover of plant genera were estimated in plots subjected to three intensity levels of hog rooting then appraised inside and outside of exclosures for 7 years. Spatial data was collected to compare areas with and without damage from hogs to areas burned by prescribed fires from 2010–2013. Total foliar cover was reduced for 5 years with high intensity hog rooting compared to no-low intensity rooting. Cover of a keystone, bunchgrass species was reduced with high intensity hog rooting. With repeated rooting, total and graminoid foliar cover were reduced outside exclosures. Fire spread was significantly reduced in areas of hog rooting. These findings have broader implications for conservation of other fire-maintained herbaceous communities impacted by nonindigenous feral hogs.

The global marine ecosystem is changing rapidly as the result of biogeochemical cycles and ecosystem structure being altered by industrial civilization. Invasive marine species (IMS) are one of the most damaging regional consequences of human activity, and one of the most easily attributable to specific processes. This makes IMS introduction one of most tractable threats for management by appropriate policies. Once established, a different set of policies are required either to restrict IMS spread, or to attempt local eradication. The key ecosystem management tool for IMS damage mitigation is rapid, widely deployable IMS detection. Environmental Nucleic Acids (eNA), combining environmental DNA (eDNA) and environmental RNA (eRNA) analyses, have emerged as valuable tools for sensitive, cost-effective and readily deployable detection of IMS. Methods for IMS detection by eNA are still being developed through a widespread and active research community, so identifying the limitations of current processes will help prioritise eNA-based IMS detection research. We analysed and synthesised the opinions of expert marine ecosystem managers and researchers in Australia and New Zealand about the knowledge gaps and research needs for eNA-based IMS detection. This synthesis was placed in context with current research literature on what eNA technologies are currently providing as an IMS management tool; what problems exist with the current technology; and what could be done to improve this general approach. Our analyses produced a list of priorities that chart a path towards the best possible systems for IMS detection by eNA.

Studying the early stages of the introduction of non-indigenous species (NIS) is crucial as it allows immediate management actions aimed at preventing NIS spread at a time when these actions are more likely to be effective. Recent species introductions present unique opportunities to study key aspects of the invasion process. However, comprehensive information on how and when NIS are first introduced remains rare. We assessed the characteristics of the introduction of a member of the widespread Pyura stolonifera species group (Chordata, Tunicata) in Europe. These ascidians are important bioengineer species that can attain amongst the highest benthic biomass per surface area ever reported. We collected introduced individuals on the coast of the northwestern Iberian Peninsula, an area with high shipping traffic and one of the world’s most important mussel farming regions. The specimens were analysed using taxonomic and genetic tools. Both field surveys and taxonomic analysis showed that one of the African members of the species group, Pyura herdmani, has recently been introduced to Europe and, although it does not yet form the large aggregates found in the native range, it is already well-established. Genetic data revealed that only the northwest African lineage of P. herdmani has been introduced to Europe. Considering the low dispersal capabilities of the early life-history stages of P. herdmani, the introduction of this species into Europe can only be explained via human mediated transport of NIS. In order to prevent any detrimental effects on both native biota and/or economically-important anthropogenic activities, regular monitoring of recent NIS introductions is urgently required.

Invasive tree species pose major threats to various ecosystems, and their accurate identification and mapping are vital to the development of effective management strategies. Many invasive species demonstrate unique phenological characteristics that are visually identifiable through remote sensing. Previous species identification research relies heavily on the fusion of multiple remote sensing data sources, and are highly constricted in spatial scale. Here, we used high resolution, single instance, 4-band aerial imagery acquired during the blooming season to identify and map Callery pear (Pyrus calleryana) across all five New York City Boroughs (~ 1.188 km²) in urban, suburban, and non-developed environments. We compared traditional pixel-based filtering models against U-Net based convolutional neural networks (CNN). The U-Net CNN greatly outperformed the traditional pixel-based models, achieving a precision, recall, and F1 score of 86.9%, 89.5%, and 88.2% respectively compared to a performance of 47.2%, 52.7%, and 49.8% for the best of the pixel-based models. We also greatly improved CNN performance through the introduction of negative training data, specifically in non-urban areas. We show an effective deep learning strategy for identifying and mapping canopy coverage of Callery pear, which provides a base map for monitoring and management of Callery pear in the Greater New York City Metropolitan Area. More importantly, the method can be readily applicable to the mapping of Callery pear in other regions or other invasive species with unique phenological characteristics given the availability of punctual, high-resolution, multispectral imagery.

Until recently, the Kara Sea was a stable ecosystem unaffected by alien species invasions. However, at the beginning of the twenty-first century, the snow crab (Chionoecetes opilio) was detected. Studies conducted between 2013 and 2022 in Blagopoluchiya Bay (Novaya Zemlya Archipelago, Kara Sea) provided an opportunity to observe the establishment of a population of this species and its influence on benthic communities. Various sampling methods, such as trawl and grab surveys, as well as video observations, were used to study two main seabed habitats, one in the deep inner basin and the other at the sill at the bay’s exit. The study revealed significant changes in benthic ecosystems, including declines in integral benthic characteristics such as abundance, biomass, diversity, and shifts in dominant species. The response of megabenthos and macrobenthos varied between habitats, but in general, there was a sharp decline in the abundance of large bivalves and brittle stars. The observed changes were not related to environmental variability but most likely to the abundance and size structure of the snow crab. The taxonomic and size structure of the benthos changed as crab individuals increased in size, and the changes were faster and more pronounced in the area with higher crab abundance. These findings raise concerns about the potential long-term effects of the snow crab invasion on the Kara Sea ecosystem, including reduced biodiversity and changes in food webs.

This study addresses the broader issue of invasive species management, particularly within the context of highly biodiverse yet threatened ecosystems such as the Atlantic Forest in Brazil. Effective management strategies are paramount to mitigate the ecological impact of invasive species on native ecosystems. Using the case of Artocarpus heterophyllus Lam. (Moraceae), a tree native to Southeast Asia that has become invasive in some urban tropical forests in Brazil, we developed a management approach based on the tree’s life cycle and vital rates. Our disturbance analysis showed that a management strategy focused on the survival and growth of JUVENILES 1 and ADULTS 1 would be effective in reducing the population growth rate (λ). Elasticity analyses, on the other hand, indicate that the best management options are those based on the survival rates of JUVENILES 1, ADULTS 1, and ADULTS 2. To reduce the population’s λ, our management simulations suggest that small interventions are sufficient, targeting a reduction of up to 5% in survival rates, particularly in the reproductive classes. In contrast, our simulations highlight that interventions involving the removal of 30% of the population or more per year have a minimal effect on reducing the population growth rate, while gradual, long-term management is more effective. Excessive management, defined as large-scale interventions that can open large gaps in the forest (e. g. exceeding 70% removal per year), would be unnecessary, could result in the waste of financial resources, and could hinder native species’ ability to colonize the environment.

Ecosystems worldwide are struggling with increasingly high levels of human-induced stressors, impacting their ecological health at local, regional, and global scales. Among the factors affecting freshwater organisms, temperature stands out, especially given the recent escalation of global warming, with possible adverse effects. In this study, we examined the basal levels of oxidative stress parameters in the round goby Neogobius melanostomus, spanning its native and non-native ranges of occurrence. We aimed to assess five populations across transcontinental scale (Turkey, Croatia, Slovakia, Poland, Finland) to determine whether individuals already experiencing conditions other than their thermal optimum (such as those in Turkey and Finland) would display elevated non-enzymatic indicators (level of lipid peroxidation and reduced glutathione levels) and enzymatic indicators (activity of glutathione peroxidase and catalase activity) of oxidative stress compared to those inhabiting milder ecosystems. The results obtained did not align with our initial predictions. The native Turkish population exhibited the lowest values for both antioxidants and oxidative damage, indicating an efficient redox system in this species. All tested parameters showed variation among populations, as well as between tissues and sexes. Temperature did not emerge as significant factor in any of the parameters tested, while for glutathione peroxidase, our analysis indicated a positive relationship with enzyme activity and salinity. The lack of a continuous latitudinal pattern in the non-native populations suggests the species’ potential for adaptive shifts, indicating superior adaptive abilities, especially in human affected ecosystems, rather than strictly adhering to environmental gradients.

The prevention of aquatic invasive species is one of the most cost-effective management strategies for reducing negative ecological, economic, and social impacts to freshwater ecosystems. The release of leftover baitfish via the live bait trade has been identified as a high-risk pathway for introducing invasive species beyond physical barriers (e.g., mountains, dams). To assess differences in behavior surrounding live bait use and angler knowledge of invasive species, we conducted in-person angler surveys at waterbody access sites (i.e. boat ramps with available shore fishing and a shore fishing location with no boat ramp) along the Missouri River, above and below Gavins Point Dam (Yankton, South Dakota, USA). We were primarily interested in whether angler behavior and knowledge differed among fishing locations over the course of a year because of potential variation in risk. Gavins Point Dam is impervious to fish passage and prevents the spread of invasive silver carp Hypophthalmichthys molitrix and bighead carp H. nobilis (collectively known as bigheaded carp), but bigheaded carp could be transported above this dam by the use of live baitfish. Regardless of where respondents fished (above the dam/carp absent, below the dam/carp present, or both), 70% ± 11.12 of anglers used live baitfish and 57% ± 3.14 participated in ‘higher risk’ baitfish practices including release. Knowledge of bigheaded carp was limited, as only 2% ± 1.31 of respondents identified both bigheaded carp as invasive in an image collage, 51.82% ± 4.48 could not identify where invasive carp are present/absent, and 40% ± 3.34 of anglers had not received any information regarding bigheaded carp. These findings highlight limitations in angler knowledge, compliance, and identification of native and invasive species. Future implementable actions could include invasive species and baitfish release outreach via electronic media sources or additional signage that address these knowledge gaps.

The reproductive strategy of the European bitterling (Rhodeus amarus) involves an obligatory parasitic relationship with freshwater mussels from the family Unionidae. This study sets out to assess the possible threat that the invasive unionid species Sinanodonta woodiana poses to bitterling. The objective was accomplished by analysing the bitterling's reproductive preferences for S. woodiana and four native species of unionid mussels (Anodonta anatina, Unio crassus, U. pictorum and U. tumidus). We performed three experiments in a sand bottom tank. Experiments A and B lasted 20 for days and experiment C lasted 10 days. The highest numbers of eggs and embryos of bitterling in the experiment A were found in A. anatina. On the other hand, U. tumidus had the greatest number of embryos in the most developed embryonic stage (stage VI), followed by U. crassus, U. pictorum and lastly A. anatina, whereas U. crassus had the largest densities of eggs and embryos per unit gill area in cm². As hypothesized, S. woodiana did not contain a single egg or embryo which was also confirmed in the experiments B and C. Results of the experiment C had shown that the first few days bitterlings laid eggs in Unio spp. and only after that in A. anatina. Furthermore, it is evident that bitterlings favour mussels without glochidia. In conclusion, European bitterling will be threatened if an invasive species S. woodiana outcompetes the native unionid species.

Invasive ants are among the world’s most damaging invaders and are considered a significant threat to urban, natural, and agricultural habitats worldwide. Populations of invasive ants are notoriously difficult to eradicate once established and are typically managed using chemical tools, predominantly toxic baits and residual sprays. Most studies evaluating control efforts do not quantify post-treatment community-level response to control efforts, so the overall outcome of management efforts remains unknown and the efficacy of management efforts in mitigating invader impacts remains unclear. The potential of insecticide treatments to cause secondary ant invasions has not been previously examined. Secondary ant invasions, the proliferation of non-target invasive ants following efforts to suppress the dominant target invader is a potentially ubiquitous, yet rarely studied problem. Additionally, limited understanding of the interactions between co-occurring invaders can be problematic for predicting how the removal of only one invasive, a common management scenario, will affect the other invaders and native communities. The current study reports on the potential threat of secondary ant invasions following insecticide treatments and highlights future research needs to address this problem. Residual spray insecticide treatments were applied in an urban setting to control the invasive Argentine ant, Linepithema humile. While the study was limited to a single geographic area, results demonstrate that insecticide treatments can affect target and non-target species in unpredicted ways. Specifically, insecticides applied to control invasive L. humile provide effective short-term control but degrade relatively quickly and lead to secondary invasions by other invasive ants. Therefore, insecticide treatments are capable of causing secondary invasions by multiple invaders. Results demonstrate that invasive ant control is not simply precision removal of the target invader but a form of ecological disturbance with multiple positive and negative impacts on the ecosystem.