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In this article, a reaction–diffusion predator–prey equation with additive Allee effect acting on prey is investigated by twice singular perturbation analysis. Our focus is to study the traveling fronts of predator invasion under the assumption that the diffusion ability of the predator is much greater than that of the prey. Our results exhibit two kinds of traveling fronts for a Holling–Tanner system in two different limit cases. And these traveling fronts correspond to the heteroclinic connections between a saddle and either a stable node or a stable focus. In addition, we show that heteroclinic connections are formed in different ways for different limit cases. One is formed on the slow manifold, which has one time scale. While the other is formed by the intersection of the slow manifold and the fast manifold, which has two time scales. Furthermore, the existence of traveling front solutions in different limit cases is demonstrated through theoretical analysis and numerical simulation. The main tools are geometric singular perturbation theory and Bendixson’s criteria.

Invasive aquatic species continue to be a persistent problem around the world. The Trojan Y Chromosome (TYC) eradication strategy has recently been developed to help fight the problem in aquatic systems by targeting only the invasive species, sparing native marine stock. It involves rearing genetically modified samples of the invasive species and introducing them into the environment to alter the sex ratio of the invasive population. The paper is devoted to finding the optimal implementation of the TYC eradication strategy of an invasive species as well as a modified, potentially more cost-effective strategy. The modified TYC strategy (MTYC) eliminates one round of exposure to sex hormones compared to the TYC strategy. After introducing both strategies, the optimal control problems for each are formulated. The two strategies are compared through numerical simulations. Our results illustrate that the MTYC strategy, with lower implementation costs, is a better strategy option when trying to minimize the overall effective cost in most scenarios.

The Trojan Y Chromosome (TYC) strategy is a biological control method for controlling invasive populations with an XX–XY sex determinism, wherein a modified organism is introduced into an invasive population to skew the sex ratio over time, causing local extinction. However, the classical three compartment TYC model possesses blow-up solutions, for large initial conditions [Takyi EM, Beauregard MA, Griffin T, Bobo L, Parshad RD, On large and small data blow-up solutions in the Trojan Y Chromosome model, Axioms 11(3):120, 2022]. We investigate model improvements via accounting for a modified logistic term, female mating preference, competition between males and supermales and pair formation. Each one of these models is dynamically explored and is shown to possess global in-time non-negative solutions, in any parameter and initial data regime, and the models are also effective in facilitating extinction of the invasive wild type.

Addressing the international threat of invasive species to biodiversity worldwide requires an international context due to the nature of the transboundary pollution. This paper presents a comparison of strategies to address the invasive species problem in noncooperative versus cooperative differential games. Asymmetry between the countries in terms of abatement costs and damages enables the investigation of sharing rules under cooperation. The empirical analysis includes data of maritime trade as a vector of invasive species pollution at ports along the Pacific coast of NAFTA countries. The Chander/Tulkens cost sharing rule induces countries to cooperate and achieve lower invasive species stock than under noncooperation.

Colonization of ship hulls by living organisms, which occurs on molecular, microbial and macro organism levels, decreases ship performance, increases costs and is a biological problem with global consequences. Managing fouling is necessary for efficient economics and to prevent environmental damage due to introduction of invasive species. Colonization is managed by broad spectrum long-lived toxins which kill colonizers. Broad spectrum long-lived toxins build up and impact environments. Toxins damage ecosystems and directly or indirectly kill food species. Ideally, novel antifouling approaches will be compatible with existing business models and with the environment. A mixture of short-lived biologically active molecules that manage colonization has this potential. The mixture would contain a short-lived toxin that managed colonization of organisms that have no behavior and then additional molecules that interfere with the process of colonization by organisms with behavior and those that attach as part of a change in life stage. Environmentally benign antifouling approaches are novel and require cooperation rather than competition or adversarial relationships. They require cooperation by individuals with expertise from business, governmental agencies and academia. The science is likely to be easier than the necessary changes in philosophy and governance required to successfully address this and other complex global problems.

More information on the distribution of the zebra spiny eel (Macrognathus zebrinus), a non-native species recently recorded in Singapore, is provided in this study. The spiny eel is known from four reservoirs (Kranji, Lower Peirce, Lower Seletar, and Tengeh) on the island. The presence of large numbers of this species in the Kranji and Lower Seletar reservoirs indicates that the zebra spiny eel is now established in Singapore.

Researchers have argued that invasive species are the dominant biological threat to the functioning of our planet. If framed differently, invasive species are only a symptom of a more dominant biological threat: the migration of humans and their destruction and alteration of habitats. The latter argument carries substantially more weight and emphasis, with humans now concurrently affecting climate resilience. Still, the management of invasive species must be part of addressing climate mitigation and adaptation. Here, we evaluate the management issues of invasive species through a window where management is driven by the net benefits and threats associated with these species. This volume addresses governance and emerging technologies for monitoring and assessment, provides case studies, and includes examples of applications and opportunities for invasive species to participate in ecological and economic sustainability efforts.

Reservoirs in Hong Kong constitute an essential component of local freshwater habitats, but their biodiversity still needs to be better understood. This study adopted environmental DNA (eDNA) technology to assess faunal biodiversity in local reservoirs. This approach enabled the analysis of metazoan diversity in Hong Kong’s reservoirs, which would have been challenging to achieve through conventional, labourintensive, and invasive ecological surveys. We surveyed eight reservoirs of varying sizes and ages, including their catchment areas, to provide baseline information for establishing a long-term monitoring programme for local reservoir habitats. The results revealed a higher success rate in amplifying eDNA fragments from the reservoirs than from catchment areas. The cytochrome oxidase I (COI) and 18S rRNA markers exhibited differential performance in biodiversity assessment. Notably, eDNA detected known naturalised species, such as Caridina cantonensis (bee shrimp), Cryptopotamon anacoluthon (freshwater crab), Parazacco spilurus (predaceous chub), and Liniparhomaloptera disparis (Hillstream loaches). Moreover, potential exotic species, Cherax quadricarinatus (the red-clawed crayfish), Oreochromis niloticus (Nile tilapia), and Paramisgurnus dabryanus (large-scaled loach), were discovered through both eDNA metabarcoding and ecological surveys. The findings suggest that reservoir-associated human activities, such as the release of aquarium pets, are potential sources of species introduction in these freshwater habitats. Regular biodiversity monitoring using eDNA technology can be an effective tool in freshwater ecosystem management and invasive species detection.

Plant pathogens are microorganisms, such as viruses, bacteria, and fungi, native to specific geographical regions. Since development, globalisation, import/export, and travel across continents increased exponentially, these pathogens taken advantage of these additional opportunities to reach new habitats and affect the ecosystem, with severe consequences. These species are invasive pathogens and cause serious environmental, economic, and social threats to existing ecosystems. These invasive species have the potential to affect both wild and managed landscapes and deteriorate healthy ecosystems that are is vital to native plants, animals, and human life as well. These exotic and invasive species modulate the endemic structure and processes of introduced communities. In some other cases, invasive species may interrupt or alter the existing beneficial interaction mechanisms among native species, creating a severe ecological imbalance that can push native species toward the endangered species category or even in some cases to extinction. Considering the potential threat, the European Union (EU) drew up a list of 20 top-priority invasive species as quarantine pests based on the potential harm they can create. The current chapter discusses invasive plant pathogens, their modes of infestation, and their potential impacts on fruit crops in EU member states.

Invasive fish species can be successfully grown in sewage-fed fish-ponds, especially treated sewage ponds. Fish species commonly grown in sewage fish ponds are bighead carp (Hypophthalmichthys nobilis), silver carp (Hypophthalmichthys molitrix), Nile tilapia (Oreochromis niloticus), grass carp (Ctenopharyngodon idella), common carp (Cyprinus carpio), and catfish species, such as African catfish (Clarias gariepinus) and walking catfish (Clarias batrachus). These fish are known to be invasive or potential invasive species and can tolerate extreme environments, such as those with high temperatures and wide ranges of salinity, pH, dissolved oxygen, and ammonia. Among the fish used in sewage-fed fishponds, tilapia exhibit the best survival in sewage. However, inorganic pollutants (heavy metals), organic pollutants (such as pesticides), and pathogens (such as bacteria, viruses, and parasites) in sewage cause morphological and physiological alterations in organs. Fortunately, these sewage pollutants mainly accumulate in the viscera (especially the liver and gill) and less in the muscle (the edible part of the fish). Furthermore, these undesirable pollutants and pathogens are generally within ranges suitable for human consumption. The information in this chapter is expected to serve as a reference for the management of invasive fish species.