Ecosystem of Caspian Sea threatened by pet-traded non-indigenous crayfish

Freshwater ecosystems are particularly vulnerable to biological invasions; the aquatic animal pet trade has been recognized as a significant pathway of introductions. Crayfish are considered a model group of traded organisms with a series of highly successful species already established in the wild, having the potential to negatively influence both indigenous crayfish species (ICS) as well as alter occupied ecosystems. Eastern Europe includes the entire native ranges of indigenous Astacus leptodactylus sensu lato and A. pachypus. This region has been largely overlooked and considered relatively safe from the adverse impacts of non-indigenous crayfish species (NICS). In this study, we evaluated the crayfish pet trade in the Lower Volga Region with special emphasis on Astrakhan, the biggest city of Russian Federation in the region located just in the delta of Volga River, thus being a potential gateway of introductions to the Caspian Sea and adjacent freshwaters. The local pet trade involves 12 NICS. Considering their origin, availability, probability of establishment, invasiveness and further aspects, Procambarus fallax f. virginalis, P. clarkii and Cherax destructor are considered potentially the most problematic, including transmission of diseases like crayfish plague caused by Aphanomyces astaci or white spot syndrome virus. Taking this information as a whole, the availability of NICS with a high probability of overlapping the entire range of European ICS means that attention is warranted. Further research is needed to corroborate the abilities of NICS and their associated diseases to withstand specific conditions of the Caspian Sea as well as the adjacent Black and Azov Seas, all possessing different degrees of elevated salinity.     

Anthropogenic signature in the incidence and distribution of an emerging pathogen of poplars

The introduction and establishment of non-native plant pathogens into new areas can result in severe outbreaks. Septoria leaf spot and canker caused by Sphaerulina musiva is one of the most damaging poplar diseases in northeastern and north-central North America. Stem and branch cankers can be devastating on susceptible trees, leading to tree death and reduced biomass in commercial plantations. In the Pacific Northwest region of North America, the first report of the disease was made in 2006 in the Fraser Valley of British Columbia (BC), Canada. To investigate the incidence and distribution of S. musiva from its point of introduction into BC, five plantations of Populus trichocarpa (black cottonwood), 500 P. trichocarpa trees from natural populations, and 23 plantations of hybrid poplars were surveyed by using real-time PCR assays targeting S. musiva and its native sister species, S. populicola. Our survey suggests a strong anthropogenic signature to the emergence of the non-native S. musiva. Detection frequency of S. musiva was high in hybrid poplar plantations (116 trees infected, 54.2 % of the sampled trees), while detection of the native S. populicola was limited to 13.1 % (22 trees infected). By contrast, in natural stands of P. trichocarpa, less than 2 % of the trees were positive for S. musiva (7 trees) while ~75 % were positive for S. populicola (433 trees). All the S. musiva detections in natural stands of the native P. trichocarpa were from trees located in the vicinity (<2.5 km) of hybrid poplar plantations. Identification of the genotypes found in the hybrid poplar plantations revealed that they are in majority F1 progeny from P. trichocarpa × P. deltoides (T × D) (82 %) and P. nigra × P. maximowiczii (N × M) (7.8 %) crosses, which are generally susceptible (intermediate level of susceptibility between the two parental species) to the canker disease. Our results suggest that the emergence of S. musiva in BC is related to the planting of susceptible hybrid poplars. Even if the disease has not yet established itself in natural poplar populations outside of the Fraser Valley, infected plantations could act as a reservoir that could promote its spread into nearby native P. trichocarpa populations.     

Mycorrhizal detection of native and non-native truffles in a historic arboretum and the discovery of a new North American species, <Emphasis Type="Italic">Tuber arnoldianum</Emphasis> sp. nov.

During a study comparing the ectomycorrhizal root communities in a native forest with those at the Arnold Arboretum in Massachusetts (USA), the European species Tuber borchii was detected on the roots of a native red oak in the arboretum over two successive years. Since T. borchii is an economically important edible truffle native to Europe, we conducted a search of other roots in the arboretum to determine the extent of colonization. We also wanted to determine whether other non-native Tuber species had been inadvertently introduced into this 140-year-old Arboretum because many trees were imported into the site with intact soil and roots prior to the 1921 USDA ban on these horticultural practices in the USA. While T. borchii was not found on other trees, seven other native and exotic Tuber species were detected. Among the North American Tuber species detected from ectomycorrhizae, we also collected ascomata of a previously unknown species described here as Tuber arnoldianum. This new species was found colonizing both native and non-native tree roots. Other ectomycorrhizal taxa that were detected included basidiomycetes in the genera Amanita, Russula, Tomentella, and ascomycetes belonging to Pachyphlodes, Helvella, Genea, and Trichophaea. We clarify the phylogenetic relationships of each of the Tuber species detected in this study, and we discuss their distribution on both native and non-native host trees.     

Identifying the ecological and societal consequences of a decline in <Emphasis Type="Italic">Buxus</Emphasis> forests in Europe and the Caucasus

The potential impact of new invasive tree pests and diseases is usually quantified in economic terms. The ecological and social impacts are less often assessed. Using a comprehensive literature review we assess the potential ecological and social impact of two non-native invasive species (the box tree moth, Cydalima perspectalis and the fungus Calonectria pseudonaviculata) that threaten the survival of box tree, Buxus spp. in forests in Europe and the Caucasus. A total of 132 fungi, 12 chromista (algae), 98 invertebrate and 44 lichens were found to use Buxus spp. Of these, 43 fungi, 3 chromista and 18 invertebrate species have only been recorded on Buxus spp., suggesting that these species are obligate on Buxus spp. and are most at risk from in the loss of Buxus spp. due to these invasive pest and disease species. Buxus spp. was shown to be important for soil stability and water quality but there was no information on other ecosystem functions provided by Buxus spp. Buxus was found to be of considerable historical cultural importance but there was very limited information on current social values and uses. Buxus trees, wood and leaves are associated with different folklore and sacred rites which are still particularly important in the Caucasus. While we could not find any assessment of the economic value of Buxus forests the biodiversity, cultural and social values of Buxus identified here indicate that its loss could have major indirect and non-market economic effects. This work highlights the importance of studying the ecological and societal implications of biological invasions.     

Trade-offs between growth and defence in two phylogenetically close invasive species

The success of an invasive plant species could be explained by trade-off between growth and defence. The aim of this paper was to explore the responses of two non-native aquatic macrophytes Elodea canadensis and Elodea nuttallii to herbivores in their introduced range. We assessed the palatability of the two phylogenetically close aquatic plant species in field and their responses to gammarid consumption in spring, summer and autumn in a microcosm experiment. We measured the variation of functional traits for each season. The traits selected were those judged most closely related to the allocation of resources to growth or to resistance against herbivores. We clearly established that the strategies of the two species were different and that their consumption rate differed in summer. In summer, E. canadensis allocated more of its resources to structural defence (leaf toughness). The increase in leaf thickness reduced the palatability of E. canadensis, whereas E. nuttallii stimulated its growth. Moreover, a decrease in dry matter content in E. nuttallii was found during the growing season in field. In autumn, both plant species accumulated nitrogen and phosphorus in their tissues. We also demonstrated that neither species induced efficient chemical defences against the herbivores. The different strategies of these two Elodea species could be explained by their different resident times in the introduced area and by an adaptation of the naturalised E. canadensis to herbivores.     

Spatial distribution shifts in two temperate fish species associated to a newly-introduced tropical seaweed invasion

The establishment of non-native habitat-forming seaweeds into new areas may trigger important changes in ecosystem functioning, yet their community and ecosystem-level effects remain largely understudied. Here we studied the spatial distribution of two common fish species (Xyrichtys novacula and Bothus podas) which are key components of communities in unconsolidated bottoms of temperate areas regarding the colonization of the newly-introduced tropical seaweed Halimeda incrassata in the Mediterranean Sea. We used a spatially-explicit before-after-control-impact model and a unique data-set formed by 6 years of fine-scale spatial information of fish and seaweed distribution and abundance. We demonstrate a long-term alteration on the spatial distribution of X. novacula characterized by a shift towards non-native H. incrassata beds, while no effect on B. podas. The introduction of the tropical seaweed H. incrassata has led to the re-distribution of X. novacula, potentially by harbouring a greater biodiversity of species at the base of the food-web through adding biogenic structure to an otherwise bare sediment. Our work demonstrates that non-native tropical habitat-forming species have the potential to maintain or even enhance fish abundance in unconsolidated bottoms in temperate areas potentially altering the functioning of native habitats.     

The widespread and overlooked replacement of <Emphasis Type="Italic">Spartina maritima</Emphasis> by non-indigenous <Emphasis Type="Italic">S. anglica</Emphasis> and <Emphasis Type="Italic">S. townsendii</Emphasis> in north-western Adriatic saltmarshes

Non-native Spartina spp. have invaded many coastal saltmarshes worldwide. Introduced Spartina may cause problems like displacement of native vegetation and hybridisation with native species, leading to changes to relevant ecosystem services and saltmarsh geomorphology. Here we report the extensive and so far overlooked replacement of the native Spartina maritima by non-native S. anglica and S. townsendii along 400 km of the coast of the north-western Adriatic Sea (Mediterranean Sea). We analysed the distribution of both native and non-native Spartina spp. along the six main saltmarsh areas in the region, and produced maps of their presence by using a combination of genetic tools, morphological analysis and geotagged photographs, complemented with field observations. We also reviewed historical herbaria from the region to explore when the first non-native introductions could have occured. We found that S. anglica and S. townsendii are unexpectedly widespread, having established along the whole study region, in one lagoon totally replacing the local native species. Its introduction happened virtually unnoticed, and misidentified herbarium specimens date back as early as 1987. We discuss the ecological implications of this overlooked extensive replacement, and the need for a comprehensive assessment of the status of the saltmarshes in this region, both to protect the few remaining patches of the native S. maritima and control the spread of the non-native species across the Mediterranean Sea.     

Non-indigenous signal crayfish <Emphasis Type="Italic">Pacifastacus leniusculus</Emphasis> are now common in Danish streams: preliminary status for national distribution and protective actions

North American signal crayfish (Pacifastacus leniusculus) are invasive in Europe and pose a serious threat to indigenous European crayfish such as the noble crayfish (Astacus astacus). This is mainly because signal crayfish is the carrier of crayfish plague agent, Aphanomyces astaci, which freshwater crayfish from all other continents are highly susceptible to. Until recently, the distribution of signal crayfish in Danish streams has been considered local and restricted to a small geographical area. Here we present data demonstrating that signal crayfish are now widespread in Denmark, including the largest Danish river, River Gudenå. For one of the rivers where co-existing signal crayfish and indigenous noble crayfish were documented, sensitive molecular tests could not detect the crayfish plague agent Aphanomyces astaci in either species. Hence, it seems that not all signal crayfish are chronic carriers of the disease. For the remaining freshwater systems with the introduced signal crayfish, the infection status is presently unknown. Large areas of the freshwater systems in Denmark also remain unexplored with respect to presence/absence of signal crayfish and noble crayfish. Nevertheless, our preliminary data that covers about 14% of the Danish rivers, strongly suggests that signal crayfish should be considered as a common invader that poses an increased threat to the biota in Danish streams, in particular for the indigenous noble crayfish.     

Ecological niche differentiation between native and non-native shrimps in the northern Baltic Sea

Invasions of non-native species are modifying global biodiversity but the ecological mechanisms underlying invasion processes are still not well understood. A degree of niche separation of non-native and sympatric native species can possibly explain the success of novel species in their new environment. In this study, we quantified experimentally and in situ the environmental niche space of caridean shrimps (native Crangon crangon and Palaemon adspersus, non-native Palaemon elegans) inhabiting the northern Baltic Sea. Field studies showed that the non-native P. elegans had wider geographical range compared to native species although the level of habitat specialization was similar in both Palaemon species. There were clear differences in shrimp habitat occupancy with P. elegans inhabiting lower salinity areas and more eutrophicated habitats compared to the native species. Consequently, the non-native shrimp has occupied large areas of the northern Baltic Sea that were previously devoid of the native shrimps. Experiments demonstrated that the non-native shrimp had higher affinity to vegetated substrates compared to native species. The study suggests that the abilities of the non-native shrimp to thrive in more stressful habitats (lower salinity, higher eutrophication), that are sub-optimal for native shrimps, plausibly explain the invasion success of P. elegans.     

Functional distance and establishment of non-native species with complex life cycles

More than 80% of animals have complex life cycles and undergo distinct changes in ecology and morphology during development. The strength and type of factors regulating each life-stage may differ as an organism may occupy different niches during ontogeny. We examined the functional distance at larval and adult life-stages of two non-native anurans (Green Tree Frog [Hyla cinerea] and Bullfrog [Lithobates catesbeianus]) that have established in a Chihuahuan Desert anuran assemblage in Big Bend National Park. Both life stages of both non-native species occupied niche space outside of the native assemblage. At the larval stage, the ability of the tadpoles to utilize permanent aquatic habitats and coexist with predatory fishes differentiated the non-native species from the majority of the native species that are restricted to temporary pools. At the post-metamorphic life stage, each species appears to have established by exploiting unoccupied habitat and trophic niches in the recipient community. The arboreal habits of H. cinerea may enable it to utilize resources in microhabitats that are otherwise not used by native species because arboreal frogs are absent from this native assemblage. The large body size of post-metamorphic L. catesbeianus may enable it to utilize larger food resources that are otherwise unavailable to the smaller-bodied natives. Separate comparison of larval and adult functional traits between non-natives and the native community may help predict their potential establishment or invasion success as well as aid in the development of stage-specific control or eradication efforts.     

Introgression from non-native species unveils a hidden threat to the migratory Neotropical fish <Emphasis Type="Italic">Prochilodus hartii</Emphasis>

Invasive species are one of the greatest threats to biodiversity, due to competition, predation, pathogen spread, and hybridization. The latter may remain undetected and impair the survival of species, due to genetic admixture and hybrid swarming (i.e., interbreeding between hybrid individuals and backcrossing with parental species). The impact of invasive species remains poorly studied in the Neotropical ichthyofauna, particularly when considering the potential for hybridization between native and introduced species. Due to fisheries importance and its commercial value, species of the Prochilodus genus have been introduced to other catchments in Brazil. Here, we evaluate the introduction of non-native Prochilodus species and the potential effect of hybridization with the native migratory fish P. hartii. To evaluate possible introgression of Prochilodus spp. to P. hartii in the Jequitinhonha river basin (JRB), we employed a morphogenetic approach, analysing 219 specimens sampled from a broad extent of the river basin. Morphological analyses using meristic characters were incongruent with molecular identification by DNA barcoding (COI) in 22.83% of the analysed specimens. Haplotypes from three non-native species (P. argenteus, P. costatus, and P. lineatus) were recovered from specimens morphologically identified as P. hartii. Hybridization between P. hartii and introduced species was confirmed using co-dominant nuclear microsatellite markers. We observed a pronounced introgression pattern in this Neotropical basin, and paradoxically, despite being one of the most abundant migratory species native to the JRB, due to ongoing levels of introgression, P. hartii’s genetic integrity and conservation might be affected.     

California vernal pool endemic responses to hydroperiod,plant thatch,and nutrients

Many endemic large branchiopods inhabit ephemeral freshwater ecosystems, including California vernal pools. Hydroperiod, inundation length, has been well studied in these systems that cycle between aquatic and terrestrial phases, but species’ responses to other ecological processes are still poorly known. For example, temporal (plant thatch from the previous terrestrial phase) and spatial (nutrient runoff) factors may have strong effects on emergence and population densities during the aquatic phase. We examined the effects of hydroperiod stability, thatch, and nutrients on the emergence and density of 4 vernal pool endemic species: Branchinecta lynchi (Anostraca), Linderiella occidentalis (Anostraca), Lepidurus packardi (Notostraca), and Cyzicus californicus (Spinicaudata). A full factorial mesocosm experiment was conducted which measured species densities, along with water quality variables. Hydroperiod and thatch differentially affected 3 of the 4 species based on emergence timing and life cycle. Treatments had effects on many water quality variables, and these variables were correlated with densities. These results highlight how hydroperiod stability along with other processes can affect large branchiopod species in temporary freshwater ecosystems. California vernal pools are a greatly reduced habitat rich in endemic and endangered species (including Branchinecta lynchi and Lepidurus packardi), and therefore, these results have implications for conservation and management.     

Life history traits determine the differential vulnerability of native and invasive apple snails (<Emphasis Type="Italic">Pomacea</Emphasis> spp.) to a shared juvenile-stage predator

The vulnerability of gastropods to their predators varies with life history traits such as morphology, body size, behavior, and growth rates as well as predator size. A recent study suggested that the invasive apple snail, Pomacea maculata, was considerably more vulnerable to crayfish predators than the native Florida apple snail, P. paludosa. The difference was hypothesized to be caused by the relatively small hatchling size of P. maculata. To test this hypothesis, we conducted a series of feeding assays designed to quantify maximum feeding rates and selective foraging of crayfish on apple snails. The rate at which crayfish killed individual P. maculata (i.e., kill rates) decreased with snail size, and kill rates on both species increased with crayfish size. Kill rates on juvenile P. maculata were higher than kill rates on size-matched hatchling P. paludosa, and crayfish fed selectively on P. maculata when offered mixed groups of size-matched snails. Further analyses revealed that hatchling P. paludosa possess shells 1.8× heavier than size-matched P. maculata suggesting differences in vulnerability to crayfish were consistent with interspecific differences in shell defenses. Differences in hatchling size and defensive traits in combination make crayfish kill rates on hatchling P. maculata approximately 15.4× faster than on hatchling P. paludosa, but the relative contribution of hatchling size to differences in apple snail vulnerability was >3× greater than the contribution of defensive traits.     

On the history of <Emphasis Type="Italic">Brasenia</Emphasis> Schreb. in the European Pleistocene

Brasenia Schreb. is a monotypic genus in the Cabombaceae, present nowadays on all continents except Europe and Antarctica. This thermophilous aquatic plant, which originated in the Tertiary, was a frequent element of aquatic plant life during the interglacial stages of the European Pleistocene. A systematic review of the palaeobotanical records of Brasenia pollen and seeds reveals its history in Europe from the Plio-Peistocene until the Eemian interglacial. Remains of Brasenia were typical for the climatic optima during each of these stages of the Pleistocene. In this paper the diversity of fossil Brasenia species is also shown. The most abundant and morphologically diverse seeds were found in sediments from eastern European sites. Brasenia species became extinct in Europe at the end of the last interglacial or at the beginning of the Weichselian glaciation. Different scenarios for their disappearance are proposed, including the specificity of the floral cycle, probable poor dispersal of seeds, or the scarcity of suitable water bodies for it to survive.     

Host selection and host switching in <Emphasis Type="Italic">Gymnolophus obscura</Emphasis> – a symbiotic ophiuroid associated with feather stars (Crinoidea: Comatulida)

The present paper aims to assess the host-selectivity and host-switching behaviour of the comatulid associated ophiuroid Gymnolohpus obscura. The relationships between size-structure, distribution and infestation characteristics of G. obscura were assessed among all available feather star species in the Bay of Nhatrang, Vietnam, together with the frequency of injuries among symbiont size classes. Our data show that despite the fairly wide host distribution ranges, not all of them are equally infested by G. obscura, likely because of host morphology, size and location on the substrate. The most preferred hosts were the comatulids Comaster nobilis and Comanthus parvicirrus, which were preferably infested by larger symbionts. The highest frequency of injuries was found in symbionts with disks ranging from 0.6 to1 cm in diameter, tracing a host-to-host migration behaviour leading to a sharp fall in abundance in the 1.1–1.5 cm size class. Our results suggest that host-switching (either between the same or among different host species) is a characteristic behaviour of G. obscura, driven by either intraspecific competition and/or by searching for more favourable trophic or protective conditions.     

Intra- and interspecific hybridization in invasive Siberian elm

Hybridization creates unique allele combinations which can facilitate the evolution of invasiveness. Frequent interspecific hybridization between the Siberian elm, Ulmus pumila, and native elm species has been detected in the Midwestern United States, Italy and Spain. However, Ulmus pumila also occurs in the western United States and Argentina, regions where no native elm species capable of hybridizing with it occurs. We examined whether inter- or intraspecific hybridization could be detected in these regions. Nuclear markers and the program STRUCTURE helped detect interspecific hybridization and determine the population genetic structure in both the native and the two non-native ranges. Chloroplast markers identified sources of introduction into these two non-native ranges. No significant interspecific hybridization was detected between U. pumila and U. rubra in the western United States or between U. pumila and U. minor in Argentina and vice versa. However, the genetic findings supported the presence of intraspecific hybridization and high levels of genetic diversity in both non-native ranges. The evidence presented for intraspecific hybridization in the current study, combined with reports of interspecific hybridization from previous studies, identifies elm as a genus where both inter- and intraspecific hybridization may occur and help maintain high levels of genetic diversity potentially associated with invasiveness.     

Differential vulnerability of two sympatric tadpoles to an invasive crayfish predator

Many amphibian population declines have been associated with the introduction of alien aquatic predators. Here, we explore the vulnerability of tadpoles of two sympatric Japanese species [Pelophylax nigromaculatus (PN) and Rhacophorus schlegelii (RS)] to the invasive crayfish Procambarus clarkii. We first examined the behavioral responses of the tadpoles to the cues of caged, fed crayfish predator in a controlled laboratory experiment, and subsequently tested their survival when together in the presence of free-ranging predator in outdoor mesocosms that simulated natural ponds. Only PN reduced activity level to the cues of the predator, but this apparent behavioral defense recorded in the laboratory did not result into higher survival in outdoor mesocosms. In mesocosms, PN exhibited higher biomass increment but experienced higher mortality in predator environments. The mechanism mediating mortality remains unclear though. These results indicate that sympatric prey may differentially respond and be disproportionally vulnerable to novel predators. Our study illustrates the possible contribution of a life-history trait influencing risk of predation in newly invaded systems.     

Acaricidal properties of ylang-ylang oil and star anise oil against nymphs of <Emphasis Type="Italic">Ixodes ricinus</Emphasis> (Acari: Ixodidae)

Understanding and responding to the ecological, social and economic conditions that facilitate disease emergence and transmission represents a substantial challenge for epidemiologists and health professionals. In this article we integrate knowledge about the human and the vector population, to provide a context from which to examine the underlying causal factors of D. marginatus-borne diseases emergence in the study area. Within this framework we analyse the biotic and abiotic factors that drive D. marginatus population dynamics and the role of its typical host for dispersal. These investigations suggest that D. marginatus is a tick species prone to spatially overlap its presence with human population presence. Then we consider the public health implications for the residents, when simply carrying out trivial outdoor activities may increase the risk to contact an infected tick.     

<Emphasis Type="Italic">Emergomyces</Emphasis>: a New Genus of Dimorphic Fungal Pathogens Causing Disseminated Disease among Immunocompromised Persons Globally

Purpose of Review

The emergence of a group of previously unknown or unrecognized dimorphic fungal species causing systemic human disease resulted in taxonomic shifts and the creation of a new genus, Emergomyces, within Onygenales. We review the morphology, taxonomy, physiology, and ecology of Emergomyces spp., and the epidemiology, clinicopathology, diagnosis, and management of disease.

Recent Findings

Emergomyces species have been reported as causes of human disease in Europe, Asia, Africa, and North America. Es. pasteurianus is most cosmopolitan, and Es. africanus, in southern Africa, causes the largest reported disease burden; in fact, emergomycosis is the most common endemic mycosis diagnosed in South Africa. The classic clinical picture is of disseminated disease, often with cutaneous involvement, in immunocompromised individuals.

Summary

Members of the genus Emergomyces are uncommon but important agents of systemic disease in immunocompromised hosts worldwide. Knowledge gaps include the biology of the fungus, and the pathophysiology and management of disease.

     

Trophic consequences of non-native pumpkinseed <Emphasis Type="Italic">Lepomis gibbosus</Emphasis> for native pond fishes

Introduced non-native fishes can cause considerable adverse impacts on freshwater ecosystems. The pumpkinseed Lepomis gibbosus, a North American centrarchid, is one of the most widely distributed non-native fishes in Europe, having established self-sustaining populations in at least 28 countries, including the U.K. where it is predicted to become invasive under warmer climate conditions. To predict the consequences of increased invasiveness, a field experiment was completed over a summer period using a Control comprising of an assemblage of native fishes of known starting abundance and a Treatment using the same assemblage but with elevated L. gibbosus densities. The trophic consequences of L. gibbosus invasion were assessed with stable isotope analysis and associated metrics including the isotopic niche, measured as standard ellipse area. The isotopic niches of native gudgeon Gobio gobio and roach Rutilus rutilus overlapped substantially with that of non-native L. gibbosus, and were also substantially reduced in size compared to ponds where L. gibbosus were absent. This suggests these native fishes shifted to a more specialized diet in L. gibbosus presence. Both of these native fishes also demonstrated a concomitant and significant reduction in their trophic position in L. gibbosus presence, with a significant decrease also evident in the somatic growth rate and body condition of G. gobio. Thus, there were marked changes detected in the isotopic ecology and growth rates of the native fish in the presence of non-native L. gibbosus. The implications of these results for present and future invaded pond communities are discussed.