Presence of invasive Gambusia alters ecological communities and the functions they perform in lentic ecosystems

2017 ◽  
Vol 68 (10) ◽  
pp. 1867 ◽  
Author(s):  
Charles Hinchliffe ◽  
Trisha Atwood ◽  
Quinn Ollivier ◽  
Edd Hammill

By acting as novel competitors and predators, a single invasive species can detrimentally affect multiple native species in different trophic levels. Although quantifying invasive effects through single-species interactions is important, understanding their effect on ecosystems as a whole is vital to enable effective protection and management. This is particularly true in freshwater ecosystems, where invasive species constitute the single greatest threat to biodiversity. Poeciliid fishes of the genus Gambusia are among the most widespread invasive species on earth. In the present study of lentic ecosystems (i.e. lakes), we first showed that Gambusia alter zooplankton community composition and size distribution, likely through size-selective predation. Second, we demonstrate that benthic macroinvertebrate communities significantly differ between sites with and without invasive Gambusia. The presence of Gambusia appears to reduce leaf-litter decomposition rates, which is likely an indirect effect of reductions in detritivore abundances. Reductions in decomposition rates found in the present study suggest that through trophic cascades, invasive Gambusia is able to indirectly alter ecosystem functions. The study has highlighted that the widespread effects of invasive aquatic species are able to permeate through entire ecosystems, being more pervasive than previously recognised.

2017 ◽  
Vol 13 (11) ◽  
pp. 20170374
Author(s):  
Lydia Wong ◽  
Tess Nahanni Grainger ◽  
Denon Start ◽  
Benjamin Gilbert

Species interactions are central to our understanding of ecological communities, but may change rapidly with the introduction of invasive species. Invasive species can alter species interactions and community dynamics directly by having larger detrimental effects on some species than others, or indirectly by changing the ways in which native species compete among themselves. We tested the direct and indirect effects of an invasive aphid herbivore on a native aphid species and two host milkweed species. The invasive aphid caused a 10-fold decrease in native aphid populations, and a 30% increase in plant mortality (direct effects). The invasive aphid also increased the strength of interspecific competition between the two native plant hosts (indirect effects). By investigating the role that indirect effects play in shaping species interactions in native communities, our study highlights an understudied component of species invasions.


Author(s):  
Stephanie G. Yelenik ◽  
Carla M. D'Antonio ◽  
Evan M. Rehm ◽  
Iain R. Caldwell

Abstract Unlike traditional successional theory, Alternate Stable Equilibrium (ASE) theory posits that more than one community state is possible in a single environment, depending on the order that species arrive. ASE theory is often invoked in management situations where initial stressors have been removed, but native-dominated communities are not returning to degraded areas. Fundamental to this theory is the assumption that equilibria are maintained by positive feedbacks between colonizers and their environment. While ASE has been relatively well studied in aquatic ecosystems, more complex terrestrial systems offer multiple challenges, including species interactions across trophic levels that can lead to multiple feedbacks. Here, we discuss ASE theory as it applies to terrestrial, invaded ecosystems, and detail a case study from Hawai'i that exemplifies how species interactions can favour the persistence of invaders, and how an understanding of interactions and feedbacks can be used to guide management. Our system includes intact native-dominated mesic forest and areas cleared for pasture, planted with non-native grasses, and later planted with a monoculture of a native nitrogen-fixing tree in an effort to restore forests. We discuss interactions between birds, understorey fruiting native species, understorey non-native grasses, soils and bryophytes in separate feedback mechanisms, and explain our efforts to identify which of these feedbacks is most important to address in a management context. Finally, we suggest that using models can help overcome some of the challenges that terrestrial ecosystems pose when studying ASE.


Biology ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 42
Author(s):  
Vojsava Gjoni ◽  
Douglas Stewart Glazier

Recently, several studies have reported relationships between the abundance of organisms in an ecological community and their mean body size (called cross-community scaling relationships: CCSRs) that can be described by simple power functions. A primary focus of these studies has been on the scaling exponent (slope) and whether it approximates −3/4, as predicted by Damuth’s rule and the metabolic theory in ecology. However, some CCSR studies have reported scaling exponents significantly different from the theoretical value of −3/4. Why this variation occurs is still largely unknown. The purpose of our commentary is to show the value of examining both the slopes and elevations of CCSRs and how various ecological factors may affect them. As a heuristic exercise, we reanalyzed three published data sets based on phytoplankton, rodent, and macroinvertebrate assemblages that we subdivided according to three distinctly different ecological factors (i.e., climate zone, season, and trophic level). Our analyses reveal significant variation in either or both the CCSR slopes and elevations for marine phytoplankton communities across climate zones, a desert rodent community across seasons, and saltwater lagoon macroinvertebrate communities across trophic levels. We conclude that achieving a comprehensive understanding of abundance-size relationships at the community level will require consideration of both slopes and elevations of these relationships and their possible variation in different ecological contexts.


2014 ◽  
Vol 60 (3) ◽  
pp. 417-427 ◽  
Author(s):  
Tristan Juette ◽  
Julien Cucherousset ◽  
Julien Cote

Abstract While the ecological impacts of invasive species have been demonstrated for many taxonomic groups, the potential effects of behavioural variation among non-native individuals (i.e. personality) on these impacts have been largely overlooked. This is despite the fact that recent studies have demonstrated that, by nature, the three first stages of biological invasions (i.e. transport, establishment and spread) can lead to personality-biased populations. Freshwater ecosystems provide a unique opportunity to investigate this issue, notably because the ecological impacts of non-native species have been extensively documented and because animal personality has been widely studied using freshwater model species. Here, we aim at developing some perspectives on the potential effects of animal personality on the ecological impacts of freshwater non-native species across levels of biological organizations. At the individual level, personality types have been demonstrated to affect the physiolo- gy, metabolism, life history traits and fitness of individuals. We used these effects to discuss how they could subsequently impact invaded populations and, in turn, recipient communities. We also discussed how these might translate into changes in the structure of food webs and the functioning of invaded ecosystems. Finally we discussed how these perspectives could interact with the management of invasive species.


2021 ◽  
Vol 118 (12) ◽  
pp. e2023872118
Author(s):  
Ignasi Bartomeus ◽  
Serguei Saavedra ◽  
Rudolf P. Rohr ◽  
Oscar Godoy

Ecological theory predicts that species interactions embedded in multitrophic networks shape the opportunities for species to persist. However, the lack of experimental support of this prediction has limited our understanding of how species interactions occurring within and across trophic levels simultaneously regulate the maintenance of biodiversity. Here, we integrate a mathematical approach and detailed experiments in plant–pollinator communities to demonstrate the need to jointly account for species interactions within and across trophic levels when estimating the ability of species to persist. Within the plant trophic level, we show that the persistence probability of plant species increases when introducing the effects of plant–pollinator interactions. Across trophic levels, we show that the persistence probabilities of both plants and pollinators exhibit idiosyncratic changes when experimentally manipulating the multitrophic structure. Importantly, these idiosyncratic effects are not recovered by traditional simulations. Our work provides tractable experimental and theoretical platforms upon which it is possible to investigate the multitrophic factors affecting species persistence in ecological communities.


<em>Abstract</em>.—Invasive species are one of the dominant problems fisheries managers face when dealing with management, conservation, or preservation of native fishes. The primary concern is the potential for negative interactions between invasive and native species where the outcome is reduced abundance, fitness, growth, or extirpated native fish species. These negative interactions can come from direct competition for resources, vectors for the spread of disease or parasites, and subtle effects such as altering the flow of energy within and among other trophic levels. Paddlefish <em>Polyodon spathula </em>are not exempt from these threats and may even be at a higher risk because they are endemic to historically lotic systems in the central United States where many invasive species are now becoming established. The most prominent invasive threat to paddlefish may be from fellow filter-feeders bighead carp <em>Hypophthalmichthys nobilis </em>and silver carp <em>H. molitrix </em>because they consume similar food resources, possibly displace other pelagic species, and can also change the plankton community to one that cannot be as efficiently used by paddlefish. These two carp species have had a negative influence on native fish communities in other parts of the world, and have been shown to negatively interact with juvenile paddlefish in North America. Response plans that implement a movement barrier or removal of invasive species may also have ramifications for paddlefish in that they restrict movement patterns or reduce abundances as bycatch through harvest schemes. Gaining insights into potential invasive species threats to paddlefish is critical so that informed decisions can be made to prevent ecological damage from the invasive species while optimizing sustainability of native species.


Author(s):  
Stephanie G. Yelenik ◽  
◽  
Carla M. D’Antonio ◽  
Evan M. Rehm ◽  
Iain R. Caldwell ◽  
...  

Unlike traditional successional theory, Alternate Stable Equilibrium (ASE) theory posits that more than one community state is possible in a single environment, depending on the order that species arrive. ASE theory is often invoked in management situations where initial stressors have been removed, but native-dominated communities are not returning to degraded areas. Fundamental to this theory is the assumption that equilibria are maintained by positive feedbacks between colonizers and their environment. While ASE has been relatively well studied in aquatic ecosystems, more complex terrestrial systems offer multiple challenges, including species interactions across trophic levels that can lead to multiple feedbacks. Here, we discuss ASE theory as it applies to terrestrial, invaded ecosystems, and detail a case study from Hawai'i that exemplifies how species interactions can favour the persistence of invaders, and how an understanding of interactions and feedbacks can be used to guide management. Our system includes intact native-dominated mesic forest and areas cleared for pasture, planted with non-native grasses, and later planted with a monoculture of a native nitrogen-fixing tree in an effort to restore forests. We discuss interactions between birds, understorey fruiting native species, understorey non-native grasses, soils and bryophytes in separate feedback mechanisms, and explain our efforts to identify which of these feedbacks is most important to address in a management context. Finally, we suggest that using models can help overcome some of the challenges that terrestrial ecosystems pose when studying ASE.


2020 ◽  
Vol 18 (2) ◽  
Author(s):  
Omar Carbajal-Becerra ◽  
Karla Judith Olvera-Rodríguez ◽  
Gabriel Mariscal de Souza ◽  
Omar Yair Durán-Rodríguez ◽  
Arely Ramírez-García ◽  
...  

ABSTRACT Pseudoxiphophorus bimaculatus is an invasive species widely spread throughout freshwater ecosystems in central Mexico, for that reason we described its trophic strategy into a gradient of environmental quality. We sampled individuals of P. bimaculatus at eight sites located in the Lerma-Chapala and Pánuco River Basins during dry season. These basins have been impacted by industrialization and urbanization processes, but are considered as water reserves in México. To evaluate the environmental quality of the river, we applied the Visual-based Habitat Assessment, the Index of Biological Integrity and the Family-level Biotic Index. We assessed the trophic guild, the diet width, the omnivory level, and the diet selectivity. We also explored the relation of trophic strategies with the habitat condition. We captured a total of 202 individuals of P. bimaculatus from 10 to 67 mm of SL, finding a total of 24 food items. The diet of P. bimaculatus was composed of terrestrial, aquatic insects and bony fish. Pseudoxiphophorus bimaculatus in some sites can feed on different trophic levels, in other it is a specialist and secondary consumer. We found that P. bimaculatus changes its diet according the alterations in the habitat structure, water quality, and biotic integrity. Moreover, this invasive species can endure changes in the trophic web and food availability.


2021 ◽  
Vol 24 (2) ◽  
pp. 13-23
Author(s):  
Atul K. Singh

Abstract India, a megadiverse tropical country is grappling with the rising trend of aquatic invasions. Out of 532 introduced non-native fish, 16 species of freshwater aquaculture and aquarium were assessed invasive by using a risk assessment protocol, ‘Fish Invasiveness Screening Test’. Six major identified invasion pathways of the aquatic invasive species were inadvertent or deliberate releases, escapes, contaminants from hatcheries, river corridors, stowaways and unaided introductions. Invasion mechanism further elucidated the factors promoting successful invasion in freshwater ecosystems. For predictive future performance of invasive fish, the concrete and predictive values based on mean abundance by weight was calculated. Over 28.67% and 29.02 % persistent increased yield of the invasive Tilapia and Common Carp respectively was predicted in the Ganga river in the coming decades. Single species Tilapia invasion facilitated multiple species fish invasion, manifesting in invasion meltdown. The trophic changes due to fish invasion exhibited biotic homogenization with trophic downgrading. Aquatic invasive species were found highly competitive interacting with native species causing serious biodiversity loss, health hazards, and economic damage consequently affecting the ecosystem services. In spite of available regulatory approaches and guidelines to manage aquatic invasive species, fish invasion has been on the rise. This paper suggests modifications and stringent implementation of the existing regulatory mechanisms besides adopting linkages, cutting-edge research on invasion science and modern molecular containment tools for effective management.


Science ◽  
2020 ◽  
Vol 368 (6497) ◽  
pp. 1377-1381 ◽  
Author(s):  
Pengjuan Zu ◽  
Karina Boege ◽  
Ek del-Val ◽  
Meredith C. Schuman ◽  
Philip C. Stevenson ◽  
...  

Plants emit an extraordinary diversity of chemicals that provide information about their identity and mediate their interactions with insects. However, most studies of this have focused on a few model species in controlled environments, limiting our capacity to understand plant-insect chemical communication in ecological communities. Here, by integrating information theory with ecological and evolutionary theories, we show that a stable information structure of plant volatile organic compounds (VOCs) can emerge from a conflicting information process between plants and herbivores. We corroborate this information “arms race” theory with field data recording plant-VOC associations and plant-herbivore interactions in a tropical dry forest. We reveal that plant VOC redundancy and herbivore specialization can be explained by a conflicting information transfer. Information-based communication approaches can increase our understanding of species interactions across trophic levels.


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