Biological Invasions最新文献

Invasive species’ plasticity and latitudinal spread have become an increasing matter of concern in rapidly changing climate. The brush-clawed shore crab (Hemigrapsus takanoi), native along northwestern Pacific shores, has established dense populations in northern European coasts. Detrimental effects in natura have been reported, such as displacement of native species and competition for shelter, rasing concerns regarding shellfish early life stages and food webs-posing a threat to wild stocks’ recruitment and aquaculture. The species has not yet been observed in southern European countries (e.g., Portugal), where niche habitats such as harbours, mudflats, and lagoons reach higher temperatures than the invaded northern range. The aims of this study were to determine H. takanoi potential to acclimate to a southern thermal range, assess thermal performance, and identify potential competitive advantages over the native shore crab Carcinus maenas. This was accomplished through individual exposure to one of three treatments, resembling a southern European thermal range (17 °C, 21 °C, or 25 °C), for 30 days. H. takanoi thrived in temperatures as high as 25 °C, a realistic thermal scenario in Óbidos Lagoon (the biggest Portuguese lagoon)—while the native shore crab C. maenas underperformed at that treatment, showing lower survival, growth, and feed intake than H. takanoi. These results suggest that H. takanoi may be able to colonise southern and warmer European locations and have higher plasticity than the native species already inhabiting areas close to its upper thermal limits. Under global warming scenarios, inferences of further latitudinal spread and increased invaded range may also be taken to the invaded northern European habitats.

Invasive species are one of the most significant factors affecting biodiversity. American mink (Neovison vison) was introduced to Hokkaido, Japan, and is known to compete with other medium-sized mammals and prey on freshwater fish. Therefore, it is important to understand their distribution and the types of environments they prefer. We developed an N. vison-specific environmental DNA (eDNA) detection assay to estimate their distribution. Applying this assay to water samples from 48 rivers in the Shiretoko Peninsula, the World Natural Heritage site in Hokkaido, N. vison-specific DNA was identified in 10 rivers. Including seven rivers from a previous study on N. vision distribution in the peninsula, the environmental characteristics of the 17 rivers with the potential establishment of N. vison populations were investigated using a generalized linear model. The evaluated environmental factors included eDNA concentrations of two salmonid species (Salvelinus curilus and Oncorhynchus masou, potential food resources for N. vison), the presence of salmon hatchery and release programs, land uses around the rivers, and river structures. While the estimated N. vison distribution did not show a clear association with the eDNA concentrations of the two salmonid species, it showed positive and significant associations with the salmon release programs (p = 0.031) and with the proportion of farmland (p = 0.034). These findings imply that human activities have the potential not only to cause the introduction of invasive species but also unintentionally to contribute to the establishment of such species in new environments.

Two tilapia species, Oreochromis aureus and Oreochromis niloticus, were introduced into Morocco in 2004 for fish farming. O. niloticus was subsequently introduced into the wild in several watersheds. During a fish survey at six locations, we observed other specimens of tilapia that appear to be more related to O. aureus. Partial sequences of COI and S7 genes and geometric morphometrics were used to assess the specific status of all the specimens. Out of 1691 specimens sampled, 159 COI and 153 S7 partial sequences were obtained and confirmed the presence of both species. O. aureus was present in part of Rabat-Salé-Kenitra region (the Nador Channel (NC), Al Kansra dam (AK) and Oued Sebou (OS)) while O. niloticus was found in the fish farm (AS), in the province of Rabat (Sidi Mohamed Ben Abdellah dam (BA)) and the region of Casablanca-Settat (Al Massira dam (AM)). A few hybrids were identified at AS and OS. Body shapes and sizes were assessed using geometric morphometrics with 18 landmarks and were found to differ significantly between O. aureus and O. niloticus. Both species exhibited significantly different allometric changes during their growth, but kept their morphological signature independently of their specific allometric changes during growth. Specimens from riverine environments (OS, NC) had a similar shape with an elongated body with a large head and eye, while individuals found in lacustrine environments (AK, AM and BM) had a larger body depth, small head and eye. Morphometrics also suggested that hybrids or sympatry could occur to a small extent in AS, OS and NC.

Recent collection efforts along the Brazilian coast revealed a Haliclona species preliminarily identified as a likely new species. However, sequencing of the 28S rRNA C-Region, a barcode marker in sponges, showed its high genetic similarity with a Haliclona sp. from Hawaiʻi (GenBank MW016137–MW016139). We applied an integrated morphological and molecular assessment, which allowed us to identify both Brazilian and Hawaiian specimens as H. (Reniera) laubenfelsi, a species with an Indo-Pacific distribution. We postulate this species to be exotic both in the Brazilian coast and in Hawaiʻi. Our evidence is based on the arrival of the species in Brazil after 2001, being first registered next to an international port. In turn, the species is distributed discontinuously in Hawaiʻi, being mainly restricted to sheltered bays and vicinities of ports, showing a predilection for anthropogenic substrates, which strengthen the hypothesis of its exotic origin. Recent collections in Hawaiʻi (2016–2018) failed to find this species in natural habitats, though it was an abundant pioneer species in Autonomous Reef Monitoring Structures. Its capacity to colonize artificial substrata may indicate either a cryptobenthic nature or an invasive potential. We highlight the need of monitoring its abundance, spatial distribution, and biotic interactions along the Brazilian coast to assess its potential environmental impacts. The full morphological description, and the molecular sequences we provided certainly will speed up the identification of this species, allowing to track its range extension.

Cities are increasingly recognised as important sites for biodiversity and essential for improving human-nature connections. However, urban areas are also hotspots for rats, which negatively impact biodiversity due to competition and depredation. Urban residents may undertake rat control on their properties, but the effectiveness of such volunteer initiatives for broader biodiversity outcomes has not been tested in urban environments. We conducted a comprehensive study inclusive of rat abundance, adult bird diversity, and bird breeding success. We monitored rat (Norway rat Rattus norvegicus; ship rat Rattus rattus) presence and modelled detection probabilities and occupancy in suburban residential backyards in Auckland, New Zealand. We also compared bird abundance and richness among backyards and recorded 140 nesting attempts from 15 bird species between September 2021 and February 2022. Despite rat control, rats were detected at some point in all backyards, though relative abundance was low, and fewer rats were detected in backyards with more frequent rat control. Higher bird abundance, and to a lesser extent richness, were associated with proximity to native vegetation patches and more frequent rat control. Overall fledging success was relatively high and predation by rats was relatively low compared to previous research. Nest survival was slightly higher for introduced bird species. Daily nest survival rate increased with nest height, proximity to native vegetation patches, and when rat detection rates decreased. Although the effect was small, frequent rat control within a backyard was associated with increased fledging success and increased bird species richness and abundance. Further research is required to explore the factors that interact with backyard rat control to improve local outcomes for birds. High levels of community participation in backyard rat control are required to improve neighbourhood-wide outcomes for birds.

Silver Carp (Hypophthalmichthys molitrix) populations have established and expanded throughout the lower Mississippi River basin (LMRB). Information pertaining to Silver Carp population mixing among rivers within the LMRB is lacking. Documented relations between Silver Carp otolith and river water barium (Ba) and strontium (Sr) microchemical signatures may enable estimation of origins of Silver Carp in the LMRB. Replicate water samples and otoliths from 308 Silver Carp were collected from the Cache, Arkansas, White, Yazoo, St. Francis, L’Anguille, and Mississippi rivers, and Merrisach Lake (situated along a canal connecting the lower reaches of the Arkansas and White rivers) within the LMRB. Water and carp otolith microchemical signatures exhibited consistent differences among water bodies. A classification and regression tree model exhibited 80% accuracy when assigning carp collected from the White, Arkansas, and Mississippi rivers based on fish-water microchemical signatures. Model accuracy decreased as smaller rivers were incorporated into models. Predicted natal origin based on otolith microchemical signatures suggested the White River (43%) and the lower Mississippi River (39%) were the likely origins for ~ 82% of the Silver Carp sampled. Despite the prevalence of adult Silver Carp within the Arkansas River system, fewer (18%) appeared to have originated there compared to the White and Mississippi rivers. Long-term water sampling and additional isotopic measurements may refine analyses to better determine the relative contributions of Silver Carp from the smaller river systems. Population mixing of Silver Carp among tributary rivers appears to be common within the LMRB, and removal efforts may benefit from evaluating the magnitude of fish movement and connectivity among rivers.

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.