Effects Of Non-native Species Research Articles

Effect of non-native species on taxonomic and functional diversity of fish communities in different river types

Recent researches suggest that functional diversity represents the response of communities to environmental alterations better than taxonomic diversity. However, there is scarce information about how the functional diversity of freshwater fishes is affected by habitat type and the dominance of non-native species. To address this question, we analysed a large database containing 15 morpho-functional traits of 61 fish species from the Pannon Biogeographic region (Hungary). Based on a fish faunistic list and relative abundance of taxa, we quantified the taxonomic and functional diversity of riverine communities for > 700 sites of six habitat types. We asked how non-native fishes affected the taxonomic and functional diversity in different river types and at the local scale (i.e. at the site level), and how the diversity measures of native fauna elements changes along the invasion gradient. Our results showed that both functional and taxonomic richness increases with habitat complexity, from small headwater streams to large rivers. Therefore taxonomic diversity served as a good proxy for functional diversity along the environmental gradient of river types. Non-natives showed considerable functional diversity relative to their species number in each habitat type. Diversity values of native fauna elements initially increased, and then showed a major decrease along the invasion gradient. River type-specific evaluations highlighted the importance of considering the proliferation of invasive species based on both taxonomic and functional diversity indices. We argue that type-specific action plans are needed in conservation management to preserve the taxonomic and functional diversity of native fishes in Hungary, but also elsewhere.

The species–area relationship in ant ecology

AbstractAimThe positive relationship between species richness and area—the species–area relationship (SAR)—is a key principle in ecology. Previous studies show large variation in the SAR across taxa collectively indicating the necessity of a taxon‐focused approach to accurately evaluate biodiversity scaling patterns. Ants are ideal for this given their global distribution and role in ecosystem functioning. Using data from insular ant communities, this study quantified and investigated various attributes of ant SARs and reviewed the SAR literature for ant faunas, world‐wide, to identify specific areas for improvement.LocationIslands around the world.TaxonAnts (Hymenoptera: Formicidae).MethodsWe aggregated data on species richness and island characteristics from previous studies on ant SARs to evaluate effects of climate, biogeographic realm, and latitude on slope values from these studies. A multimodel inference approach was used to determine the form of the different SARs, and whether there were any differences between mainland and insular SARs. We also assessed differences between mainland and insular SAR slopes and intercepts. To seek a general slope coefficient for ants, we used a mixed‐effect model. Finally, we tested for potential thresholds in the global insular SAR using piecewise regression models.ResultsThere was a negative relationship between SAR slopes and precipitation in both mainland and insular SARs, while SAR slopes and intercept values were higher in mainland compared to insular systems. Strong evidence of thresholds emerged in the global insular SAR. Finally, a general slope of 0.16 was observed for insular systems, which is lower than found in previous studies.Main ConclusionsA taxon‐focused approach proves to showcase unexpected patterns in the SAR. Ant diversity increases faster across area in mainland areas compared to true islands. The influences of climate and biogeographic realms on the ant SAR warrant deeper study. Our review highlights knowledge gaps in the ant SAR that also extend to other taxa, such as the effects of nonnative species on the SAR.

Comparative Meta-analysis Effects of Nonnative Ants (Hymenoptera: Formicidae), Ground Beetles (Coleoptera: Carabidae), and Bark and Ambrosia Beetles (Coleoptera: Curculionidae) on Native Confamilials.

Nonnative species often transform local communities to the detriment of native species. Much of the existing invasion ecology research focuses on the effects of a few extremely impactful species, and it is less clear how nonnative species which are not causing economic or ecological impacts alter closely related natives at risk of being displaced. Filling these knowledge gaps is critical because consequences of nonnative species are likely to vary depending on taxonomic scale, functional trait, and spatial or temporal niche. We conducted a meta-analysis to evaluate how biodiversity of native Formicidae (ants), Carabidae (ground beetles), and Scolytinae (bark and ambrosia beetles) species changes across a gradient of pressure from nonnative confamilials. We calculated Hill numbers for each group from data presented in literature and correlated native diversity metrics to proportion of nonnative species. Species richness of native ants was significantly negatively correlated with proportions of nonnative ants, whereas bark and ambrosia beetle metrics showed a nonsignificant negative correlation. Nonnative ground beetles had neutral effects on diversity of native ground beetles. Resulting contrasting patterns of invasive species effects on natives suggest complex biotic and abiotic factors driving effects of nonnative species in these groups. Our results suggest that a few extreme examples (e.g., red imported fire ants) drive most of the changes seen in native arthropod communities. To accurately assess impacts of invaders on native arthropod diversity, baseline data are needed, and community analyses must consider diverse functional traits of native taxa and improve the depth and breadth of community sampling.

Non-native fishes homogenize native fish communities and reduce ecosystem multifunctionality in tropical lakes over 16 years

Non-native species are considered a major global threat to biodiversity, and their expansion to new ecosystems has recently increased. However, the effect of non-native species on ecosystem functioning is poorly understood, especially in hyperdiverse tropical ecosystems of which long-term studies are scarce. We analyzed the relationship between richness, biomass, and β-diversity of non-native and native fishes during 16 years in five hyperdiverse tropical shallow lakes. We further elucidated how an observed increase in the proportion of richness, biomass, and β-diversity of non-native over native fishes affect crucial multifunctional processes of lakes (decomposition, productivity). We found a general positive relationship between the richness and biomass of non-native and native fishes. However, the slope of this relationship decreased continuously with time, displaying an increase in non-native species richness and a decrease in native species richness over time. We also detected a negative relationship between the β-diversity of non-native and native fishes over time. Moreover, the increase in the non-native:native ratio of species richness, biomass, and β-diversity over time decreased ecosystem multifunctionality. Our results suggest that non-native fishes caused a homogenization of the native fish species over time, resulting in impoverishment of ecosystem multifunctionality; in part because non-native fishes are less productive than native ones. Therefore, focus on long-term effects and use of multiple biodiversity facets (α- and β-diversity) are crucial to make reliable predictions of the effects of non-native fish species on native fishes and ecosystem functioning.

Effect of Anthropogenic Disturbance on Floristic Homogenization in the Floodplain Landscape: Insights from the Taxonomic and Functional Perspectives

Anthropogenic disturbances pose significant threats to biodiversity. However, limited information has been acquired regarding the degree of impact human disturbance has on the β-diversity of plant assemblages, especially in threatened ecosystems (e.g., floodplains). In the present study, the effects of anthropogenic disturbance on plant communities of floodplain areas (the Miya River, Mie Prefecture, Japan) were analyzed. The taxonomic and functional β-diversity among different degradation levels were compared, and the differences were assessed by tests for homogeneity in multivariate dispersions. In addition, the effects of non-native species and environmental factors on β-diversity were analyzed. As revealed from the results, anthropogenic disturbance led to taxonomic homogenization at a regional scale. The increase in non-native invasions tended to improve homogenization, whereas at a low degradation level, the occurrence of non-natives species was usually related to taxonomic differentiation. Furthermore, though the increase in non-natives and environmental parameters significantly affected the β-diversity of the floodplain area, environmental factors may be of more crucial importance than biotic interactions in shaping species assemblages in this study. The previously mentioned result is likely to be dependent on the research scale and the extent to which floodplains are disturbed. Given the significant importance of floodplains, the significance of looking at floodplains in the different levels of degradation was highlighted, and both invasion of non-native species and environmental factors should be considered to gain insights into the response of ecosystems to anthropogenic disturbance. The findings of this study suggested that conservation programs in floodplain areas should place more emphasis on the preservation of natural processes and forest resources.

Timing of oviposition influences the effects of a non-native grass on amphibian development.

Land-use change can alter the energy dynamics in aquatic systems by changing the subsidies that form the nutrient base within them. However, experimental evaluations of subsidy change often fail to consider how effects, such as differences in individual growth and survival, may differ under varying ecological contexts experienced in the field. We used a mesocosm approach to investigate how litter (Native Prairie or Non-Native Tall-Fescue Grass) surrounding wetlands and timing of oviposition affected larval amphibian development. We found that survival differed between litter types in the Early-Oviposition treatment, with nearly 100% mortality in Fescue treatments. Conversely, survival was similar across litter types in the Late Oviposition treatment (~ 43%), and larvae in Late-Fescue treatments metamorphosed more quickly and were larger post-metamorphosis than larvae in Prairie treatments. Follow-up experiments confirmed that low dissolved oxygen (DO) was responsible for high mortality in Early-Fescue treatments; high quantities of Fescue resulted in a microbial bloom that reduced DO to < 2mg/L for several days, resulting in low hatching success. This effect was eliminated in treatments with supplemental aeration. Finally, we confirmed that experimentally observed DO patterns also occurred in the field. Context (i.e., timing of inundation relative to amphibian breeding) is critical to understanding the effects of subsidies on amphibian populations; early and explosively breeding species may experience catastrophic mortality due to DO depletion; whereas, species that breed later may experience enhanced fitness of recruits. Considering the effects of non-native species across different ecological contexts is necessary for elucidating the extent of their impacts.

The effects of trout culture on diet and food availability of native freshwater fish populations

Cultivation of a species or population and distribution to various regions has raised the idea of negative impacts on native species. The effect of non-native species on native species may be caused by competition for source, predation, hybridization, and parasite/disease transport. The present study aims to evaluate the possible effects of a trout farm established on the banks of Kocabaş Stream (Çanakkale, Turkey) on feeding characteristics of some freshwater fish (Phoxinus phoxinus, Barbus oligolepis, and Squalius cii). The samples were collected monthly over a year at two stations located before and after the trout farm and at a control station on the tributary not impacted by the effects of the farm. Fish and environmental samples were gathered monthly with an electroshocker and some fishing tools between August 2015 and July 2016. The fish diet and resource incorporation into biomass were evaluated by gut content and stable isotope analyses. Changes in diet preferences when the species are exposed to source stresses and some individuals fed on farm-based feed contaminated from the farm in Kocabaş Stream. In this study, it was observed that native fish populations in aquaculture regions were influenced by diet preferences. Designing enclosed systems limiting feed and waste transit in aquaculture establishments may be suitable for sustainability of these species.

Opiliones of Canada.

The taxonomic diversity of the Opiliones fauna of Canada is reviewed and summarised. At present, 36 native and seven non-native species have been documented in Canada using traditional morphological taxonomy, although more than 20 species may remain undiscovered based on species diversity in the adjacent United States and evidence from DNA barcoding. Consequently, the native fauna is yet to be fully explored and the number, distribution and ecological effects of non-native species remain unclear. Until the 1960s, work on the Canadian Opiliones fauna was largely conducted by researchers based outside the country. From that time on, several Canadian workers became active. However, these taxonomists have now retired and no one has assumed their role. Thus, there is a need to invigorate taxonomic research on the harvestmen of Canada and for the production of easy-to-use identification tools for use by non-taxonomists.

Biogeography of a fragmenting world

editorial ISSN 1948-6596 Biogeography of a fragmenting world Part of the value of biogeography as a multidiscipli- nary transversal science is its wide applicability to processes that occur at multiple scales. One such process is the extinction of species resulting from the disappearance of their habitats. Habitat loss and fragmentation are widespread, and, together with habitat degradation and other human im- pacts, they probably constitute the aspect of global change that contributes the most to current extinc- tion rates (see, e.g., Sandom et al. 2014), although climate change and biological invasions also play significant roles in changing the ecological dynam- ics of species (see the book reviews by Hinsley 2015 and Cassey 2015 in this issue). Island biogeography is particularly useful for understanding the complex effects of habitat loss and fragmentation on biodiversity, for it provides a solid theoretical background to study and model extinction trends (Harris 1984). Using this concep- tual framework, Matthews (2015) studied different aspects of biodiversity variation in habitat frag- ments, finding that trends in these habitat islands are complex and change from one system to an- other, with traditional island biogeographic rela- tionships only being applicable to a very limited extent. Importantly, some of this lack of transfera- bility can be attributed to the effects of non-native species or the characteristics of human disturb- ance, rather than to a lack of generality of the prin- ciples of island biogeography. Further, the nature and extent of habitat degradation in the matrix surrounding the habitat islands turn out to be im- portant in Matthews’ (2015) research, adding a new dimension to island biogeographic enquiry. High-quality datasets such as the one provided by Bergamin et al. (2015) for the vegetation of the highly fragmented Brazilian Atlantic forest will fur- ther enhance our knowledge about the effects of habitat transformation on biodiversity loss. Islands can also contribute to the study of habitat change and extinctions in that they can act as natural experiments, where isolation has result- ed in the existence of many (pseudo)replicates of limited size with similar ecological conditions and similar but, at the same time, independent evolu- tionary processes and species pools. The work of Lavery (2015) on northern Melanesian mammals is a nice example of how the distribution, ecology and evolution of several groups and lineages can be studied from a holistic, multidisciplinary per- spective in archipelagos and island complexes. This integrative perspective is also adopted for the study of particular biomes, such as the South Afri- can Fynbos (Ojeda 2015), but is particularly difficult when these biomes occupy large areas or are locat- ed in areas with considerable biotic interchange. Some of the complexity of continental set- tings can be untangled by studying areas of inter- mediate isolation, such as peninsulas, and explicitly addressing temporal patterns. The combination of data on past (through pollen) and current distribu- tion of species with macroecological and multivari- ate analyses allow Gavin (2015) to study the stabil- ity of habitats in the Olympic Peninsula (Washington, USA) throughout the end of the Pleistocene and the Holocene. At a larger temporal scale, the macroevolutionary study of extinction risk allows understanding of which species may be more prone to extinction, although habitat loss continues to play a major role in determining which species may be finally lost (DeNeve et al. 2015). Here, the important development of statisti- cal tools to analyse temporal and spatial data (Dale & Fortin 2015, Hartig 2015) allows understanding of trends and drivers from multiple sources of da- ta. A multidisciplinary approach, using transversal frameworks and addressing topics of broad inter- est to biogeographers, can perhaps best account for the many facets of the impacts of global change. This major strength of biogeography is nicely encapsulated by the papers within this issue of Frontiers of Biogeography. Joaquin Hortal 1 and Richard Field 2 Frontiers of Biogeography editors-in-chief Departament of Biogeography and Global Change, Museo Nacional de Ciencias Naturales (MNCN-CSIC), 28006 Madrid, Spain. jhortal@mncn.csic.es School of Geography, University of Nottingham, NG7 2RD, UK. richard.field@nottingham.ac.uk frontiers of biogeography 7.2, 2015 — © 2015 the authors; journal compilation © 2015 The International Biogeography Society

Coexistence of the endangered, endemic Chittenango ovate amber snail (Novisuccinea chittenangoensis) and a non-native competitor

Distinguishing between non-native species that coexist with native species and those that threaten their persistence is critical for conservation and management. We investigated this distinction for a non-native terrestrial snail (Succinea sp.) (Sp. B) that occurs with the closely-related Chittenango ovate amber snail (Novisuccinea chittenangoensis) (COAS), an endangered species that is restricted to a single, known site. In 2008 and 2009, we performed ex situ competition experiments to examine the effects of density and body size of Sp. B on growth and mortality of COAS. We also conducted mark-recapture surveys from 2002 to 2009 to document trends of the in situ population of COAS and to identify spatio-temporal factors that may mitigate any competitive interactions between COAS and Sp. B. We observed lower growth rates and higher mortality rates of COAS at higher densities and larger sizes of Sp. B, indicating that the species compete. Nevertheless, population trends indicated that COAS population size was fluctuating but not in decline, and the spatial distribution, phenology, and size structure of each species indicated that there were enough mitigating factors to allow COAS to persist in the presence of Sp. B. Collectively, these results suggest that temporal niche partitioning resulting from a trade-off between growth and longevity of each species may enable their coexistence. Our results also suggest that control of Sp. B is unnecessary and, more generally, underscore the importance of conducting research aimed at understanding the effects of non-native species before instituting long-term, costly, and potentially unnecessary control measures.

Non-Native Plants Disrupt Dual Promotion of Native Alpha and Beta Diversity

Non-native species can alter patterns of species diversity at multiple spatial scales, but the processes that underlie multi-scale effects remain unclear. Here we show that non-native species reduce native diversity at multiple scales through simultaneous disruption of two processes of native community assembly: species immigration, which enhances alpha diversity, and community divergence, which enhances beta diversity. Community divergence refers to the process in which local communities diverge over time in species composition because the history of species immigration and, consequently, the way species affect one another within communities are variable among communities. Continuous experimental removal of species over four years of floodplain succession revealed that, when non-native species were excluded, stochastic variation in the timing of a dominant native species’ arrival allowed local communities to diverge, thereby enhancing beta diversity, without compromising promotion of alpha diversity by species immigration. In contrast, when non-native species were allowed to enter experimental plots, they not only reduced native alpha diversity by limiting immigration, but also diminished the dominant native species’ role in enhancing native beta diversity. Our results highlight the importance of community assembly and succession for understanding multi-scale effects of non-native species.

Double-crested Cormorant (Phalacrocorax auritus) chick bioenergetics following round goby (Neogobius melanostomus) invasion and implementation of cormorant population control

As the fish community changed in the Beaver Archipelago (northern Lake Michigan), so has the diet of breeding Double-crested Cormorants (Phalacrocorax auritus). In 2000, the energetically dense alewife (Alosa pseudoharengus) dominated the diet, but more recently, the relatively low quality round goby (Neogobius melanostomus) has become the most common prey item. Additionally, cormorant control measures have been underway in the archipelago. This study investigated decreases in cormorant chick numbers and changes in chick bioenergetics in response to this change in diet, as well as the influence of control efforts, and compared these results to an earlier study. Two colonies, one actively controlled the other only controlled following completion of this study, were investigated to determine changes in colony size throughout the breeding season, document chick diet, measure chick growth, and determine chick survivorship to fledging. The bioenergetics model estimated that in 2010, chicks consumed a greater biomass of prey to reach fledging due to the change in diet, but lower biomass overall due to fewer chicks in the system. Control efforts in combination with the change in diet reduced chick numbers. Overall, the impact of cormorant chicks on available fish biomass has declined in recent years due to control efforts. However, the birds have the potential to consume a greater biomass of round goby in the absence of control. The impact of cormorants on fisheries resources is complicated by the abundance and effects of non-native species.

Using space‐for‐time substitution and time sequence approaches in invasion ecology

Summary1. Invasion biologists use two main approaches to evaluate the effects of non‐native species (NNS) on diversity of native species (DNS), namely space‐for‐time and time approaches. These approaches have pitfalls related to lack of controls: the former lacks pre‐invasion data, while the latter often lacks data from non‐invaded sites.2. We propose a framework that combines space‐for‐time and time approaches and which should result in more focused mechanistic hypotheses and experiments to test the causes of invasibility and the effects of NNS on DNS. We illustrate the usefulness of our framework using two case studies: one with the submersed macrophyte, Hydrilla verticillata, in reservoir and the other with the fish, Geophagus proximus, in a large river–floodplain system.3. Hydrilla verticillata invaded sites with DNS similar to that found in non‐invaded sites, indicating that biotic and/or abiotic factors did not influence invasion success; however, DNS increased over time in invaded sites compared with non‐invaded sites, suggesting that H. verticillata facilitated natives. In contrast, G. proximus invaded sites with higher DNS than non‐invaded sites, suggesting that biotic and/or abiotic factors favouring natives were important for invasion success, but DNS increased in invaded and non‐invaded sites over time, indicating that an independent factor contributed to DNS increases.4. Conclusions from both studies would have been inaccurate or incomplete if the space‐for‐time and time approaches had not been used in combination as proposed in our framework.

Long-term response of the mamane forest to feral herbivore management on Mauna Kea, Hawaii.

Seven exclosure sites located on Mauna Kea, Hawaii and established in the 1960s and 70s were sampled to characterize long-term response of the mamane (Sophora chrysophylla) forest to protection from feral sheep grazing, and to assess impacts of non-native plant species and recurrent sheep presence on forest recovery. The forest provides essential habitat for an endangered bird, the palila (Loxoides bailleui). Vegetation was sampled inside exclosures during 1972–1976, 1998, and 2009, and also outside exclosures during 2009. Patterns of response varied among exclosures, but overall, mamane trees and native shrubs showed increasing cover between the 1970s and 1998, then a slowed rate of increase in cover or a decline between 1998 and 2009. Cover of native herbaceous vegetation showed variable trends between the 1970s and 1998, and then appeared to decline between 1998 and 2009. Mamane height class distributions inside exclosures indicated that recruitment was initially high but then declined as heights shifted toward larger size classes, and presumably an older age distribution. We found limited evidence of a negative effect of non-native species on forest regrowth, but the effect was not consistent over time or among sites. Recurrent sheep presence outside exclosures negatively affected mamane canopy density and perhaps tree density at all sites, and mamane condition at some sites. Our results indicate that the mamane forest has shown substantial regrowth inside exclosures at some sites, especially those protected the longest. However, these exclosures represent a small portion of the mamane forest. Sheep presence continues to impact mamane recovery outside exclosures, and thus habitat quality for the palila.

The relationship between native and non-native species differs among taxa in Canadian national parks

Invasive species are a growing international conservation concern. In Canada, the federal agency responsible for national parks, Parks Canada, has recently identified non-native species as important threats to the integrity and richness of Canadian national parks. To test for potential effects of non-native species on native richness, we examined the relationship between native and non-native/invasive species for 3 taxa—plants, mammals, and birds—in 42 Canadian national parks. We found positive relationships between native and non-native/invasive species richness for plants and birds and a negative relationship between native and non-native/invasive mammal species richness. Consistent with most large-scale studies, our results suggest that for birds and plants, regions that are good for native species are also good for non-native species. However, we provide one of the few examples of a negative relationship between native and non-native/invasive species. In mammals we show that there are more non-natives present in species-poor communities. This may indicate that non-native mammal species are having a negative impact on native species, that non-native mammal species are more able to invade richness-poor communities, or that a third factor such as fire, habitat degradation, or climate change has a negative effect on native species while having a positive effect on non-native species. In any case, it is evident that the pattern present between native and non-native mammals differs from those in plants and birds and could be representative of a negative effect associated with non-native introductions.

Plant reestablishment 15 years after the debris avalanche at Mount St. Helens, Washington

Vegetation has slowly reestablished on the debris avalanche deposit in the 15 years after the 1980 eruption of Mount St. Helens that created a 60-km 2 debris avalanche, the largest landslide in recorded history. There has been a gradual increase in species richness and cover, but only 61% of the species present on the mountain before the eruption have established on the debris avalanche deposit. Plant cover averages 38% and is extremely patchy. Life form composition changed over successional time, because part of the avalanche deposit was invaded by introduced plant species aerially seeded to reduce erosion, the site offers the opportunity to compare successional processes occurring with and without introduced species. Long-term recovery trends and effects of nonnative species on succession are important to understand since plant reestablishment practices often rely on nonnative species for enhancing vegetation recovery of denuded sites along road sides, strip mines, or other human-generated clearing. Fifteen years after the eruption and 10 years since the invasion by introduced species, plots invaded by nonnative species had greater vegetation cover and more native plant richness than plots that were not inundated. Significantly greater mortality of conifers occurred in the plots dominated by introduced species shortly after the invasion of those species, but no difference in conifer mortality occurred in the last 5 years. Even so, the plots dominated by introduced species still have fewer conifer trees. Thus, the short-term pulse of conifer mortality after the invasion of introduced species may have long-term effects on the recovery of the dominant vegetation. It will likely be decades before there is 100% plant cover on the debris avalanche deposit and a century or more before full recovery of the vegetation system.

Restoration of Lake Trout in the Great Lakes: Challenges and Strategies for Future Management

Rehabilitation of lake trout (Salvelinus namaycush) populations has shown many signs of success in Lake Superior, but few are apparent in Lakes Huron, Michigan, Erie, and Ontario. This paper identifies key factors that have blocked rehabilitation and proposes management actions to address these problems based on the proceedings of the RESTORE Conference held in 1994. Important factors that have prevented restoration were the loss of native populations and their genetic variation, excessive fishing mortality, effects of non-native species, and degradation of habitat. Strategies proposed were conservation of remaining native populations in Lake Superior, introduction to the lower four lakes of lake trout that represent a broad range of genetic diversity, control of sea lamprey populations that use the St. Marys River, reduction of fishing mortality, re-introduction of native forage fish now extinct in some lakes, establishment of lake trout on off-shore spawning areas, and the creation of new spawning shoals. Socio-cultural issues identified were the need within management agencies to integrate lake trout rehabilitation programs into their fish community and ecosystem plans, the loss of managers’and biologists’ knowledge because the program has spanned more than one human generation, and the loss of public support for the program from stakeholder groups (e.g., some anglers and commercial fishing groups). Lessons applicable to restoration programs elsewhere were: (1) species are easiest to restore in ecosystems least disturbed, (2) new research information must be efficiently transferred from science to management, and (3) long-lived species pose unique ecological and socio-cultural problems for restoration programs.