Phylogenetics of Freshwater Black Basses (Centrarchidae: Micropterus) Inferred from Restriction Endonuclease Analysis of Mitochondrial DNA

Geographic isolation and habitat specialization has aided in the evolution and genetic integrity of the micropterid bass species of North America. Members of the genus Micropterus form a close natural unit with little morphologic and meristic variation. Our goals were to measure the genetic characteristics of and distances between six black bass species by using mitochondrial DNA analysis. Mitochondrial DNA restriction fragment length polymorphisms were examined in Guadalupe bass (M. treculi), largemouth bass (M. salmoides), shoal bass (M. cataractae), smallmouth bass (M. dolomieu), spotted bass (M. punctulatus), and Suwannee bass (M. notius), using 15 restriction endonucleases. The bluegill (Lepomis macrochirus) was used as an outgroup. The phylogeny inferred from Dollo parsimony cladistic analysis concurred with published results from allozyme analyses, yet it was inconsistent with published meristic analyses. Genetic distances between species ranged from 0.0659 to 0.2145, with the largemouth and Suwannee basses showing the greatest divergence from the other black basses. The Guadalupe, smallmouth, and spotted basses were most diverged from the bluegill. The black basses diverged over a broad time frame, with estimated black bass speciation occurring during late Miocene-early Pliocene (3.30-10.73 MYA).     

Introgressive hybridization and species turnover in reservoirs: a case study involving endemic and invasive basses (Centrarchidae: <Emphasis Type="Italic">Micropterus</Emphasis>) in southeastern North America

Invasive species threaten native taxa with extirpation and extinction via several biological mechanisms. One such mechanism, hybridization and subsequent introgression of invasive alleles into native genomes is a serious concern, especially for taxa displaying weak reproductive barriers, as is the case for black basses. Black basses introduced outside of their native ranges thus pose elevated threats to endemic congeners, particularly in the southern United States where restricted ranges preclude refuge from introgression. The recently delineated Bartram’s bass (M. sp. cf M. coosae) is endemic to the upper regions of the Savannah River basin, throughout which anthropogenic modification, including impoundment, has been extensive. Non-native Alabama bass (M. henshalli) and smallmouth bass (M. dolomieu) have been introduced into this system on multiple occasions and now threaten Bartram’s bass via introgression. In this study we sampled four reservoirs (Jocassee, Keowee, Hartwell, and Russell) in the upper Savannah River during 2004 and 2010. Results from three codominant nuclear loci and one mitochondrial locus revealed extensive introgression between Alabama and Bartram’s bass. Results show that Alabama bass have replaced Bartram’s bass in lakes Keowee and Russell, where they were first introduced, while the frequencies of hybrids in lakes Jocassee and Hartwell are increasing. Hybridization involving Bartram’s bass with native largemouth bass and introduced smallmouth bass was detected in very low frequencies. Results highlight the importance of continual study over geographic and temporal scales to inform management and conservation of rare fishes threatened with extinction via interspecific hybridization.     

Examination of the effects of largemouth bass (Micropterus salmoides) and bluegill (Lepomis macrochirus) on the ecosystem attributes of lake Kawahara-oike,Nagasaki, Japan

The introduction of largemouth bass (Micropterus salmoides) and bluegill sunfish (Lepomis macrochirus) into the freshwater ecosystems of Japan has resulted in the suppression and/or replacement of native species, generating considerable concerns among resource managers. The impacts of largemouth bass and bluegill on native fauna have been examined in aquaria and isolated farm ponds, but there is limited work examining the likelihood to fundamentally modifying Japan's lakes. The objective of the present study is to examine the direct and synergistic ecological effects of largemouth bass and bluegill on the biotic communities of Lake Kawahara-oike, Nagasaki, Japan, using an ecosystem (Ecopath) modeling approach. Specifically, we examine whether the two fish species have played a critical role in shaping the trophodynamics of the lake. We attempt to shed light on the trophic interactions between largemouth bass and bluegill and subsequently evaluate to what extent these interactions facilitate their establishment at the expense of native species. We also examine how these changes propagate through the Lake Kawahara-oike food web. Our study suggests that the introduction of bluegill has induced a range of changes at multiple trophic levels. The present analysis also provides evidence that largemouth bass was unable to exert significant top-down control on the growth rates of the bluegill population. Largemouth bass and bluegill appear to prevail over the native fish species populations and can apparently coexist in large numbers in invaded lakes. Future management strategies controlling invasive species are urgently required, if the integrity of native Japanese fish communities is to be protected.     

Growth and mortality of black bass, Micropterus salmoides (Pisces, Centrachidae; Lacapède, 1802) in a reservoir in southern Brazil.

The black bass, Micropterus salmoides, was introduced to Brazil from North America in 1922. Since then the species has been reared in aquaculture facilities intended to stock reservoirs as additions to native stocks available for angling. At present no scientific information on the biology of black bass in Brazilian waters is available. Since black bass dispersion may cause severe impacts on native Brazilian fish fauna, information on the basic biological parameters of this species is necessary. The objective of the present study is to provide information on the growth, age structure, and mortality of the species in a small reservoir in southern Brazil, where the species reproduces regularly. Based on scale readings, the von Bertalanffy growth curve was calculated and compared to the length-frequency distribution of the population. Both methods showed similar results. Maximum length was about 44 cm. The mean length at the end of the first year was 23.1 cm (s.d. = 13.88); at that of the second, 37.3 cm (s.d. = 12.52); and 41.4 cm (s.d. = 9.92) at the third. Oldest fish were three years old. The growth performance index phi' was 3.28 cm year(-1). Mortality increased from 0.16 year(-1) between the first and the second cohort, to 0.8 year(-1) between the second and third. The results show that black bass in Brazil grows faster than in its area of origin, but longevity is shorter and body shape, stouter. The cause of high mortality at a relatively early age may be connected with the loss of genetic diversity due to inbreeding of the Brazilian stocks, which originated from few introduced individuals a long time ago. The fact that black bass reproduces in reservoirs and grows rapidly may be considered a threat to conserving fish diversity in Brazilian ecosystems.     

Interactions between bluefish and striped bass: Behavior of bluefish under size- and number-impaired conditions and overlap in resource use

A decline in bluefish (Pomatomus saltatrix L.) recreational landings during the 1990s and the early 2000s led to multiple theories on the ultimate cause. One theory was that a large portion of the bluefish population moved offshore and was unavailable to nearshore recreational fishers; one reason given for the movement offshore was increased competition with striped bass (Morone saxatilis W.). We conducted laboratory experiments (feeding and non-feeding) to examine behavioral interactions between adult bluefish and sub-adult striped bass in a large (121,000 L) research aquarium. Additionally, we examined diet and habitat overlap of bluefish and striped bass from the fall and spring bottom trawl surveys conducted by the National Marine Fisheries Service. Observations of feeding trials for the following treatments were made: non-impaired (i.e., same number and size of bluefish and striped bass), size-impaired (i.e., large striped bass/small bluefish), number-impaired (i.e.,10 striped bass/3bluefish), and single-species controls. Within a species, there was no difference in a variety of behavioral measures (e.g., attack rate, capture success, ingestion rate, and activity) between mixed- and control treatments under non-impaired or size-impaired conditions. However, behavior of number-impaired bluefish differed from control and size-impaired fish suggesting that striped bass may have a negative influence on bluefish foraging when bluefish are “out-numbered”. Feeding had a strong effect on swimming speeds for both species. Diet and habitat overlap between bluefish and striped bass in continental shelf waters was low. Overall, foraging behavior in mixed-species treatments and field observations suggest no competitive interactions between adult bluefish and sub-adult striped bass.     

Spawning and Brood Defense of Smallmouth Bass Under the Process of Invasion into a Novel Habitat

Smallmouth bass, Micropterus dolomieu, known as one of the world's most disastrous invasive species, was introduced into Lake Aoki, central Japan in the last 10 years and is of concern for the conservation of the native biodiversity. We investigated spawning and brood defense under novel conditions to devise measures to eradicate a local population of this species. Compared to their native habitat, the size distribution of nesting males was less skewed to the right in this invasive population but rather a skewed normal distribution probably due to prevention of younger cohorts entering the nesting stock. The number of offspring deposited in nests was not positively related to the size of the nesting male. These observations imply that a shortage of suitable nest sites leads to an escalation in male–male competition, followed by a relaxation of female mate choice based on male size. Further, when presented with a model of a potential predator of the offspring, nesting males reacted individually and the intensity of site tenacity was independent of the male size. We propose that the removal of cover accompanied by the use of native predators of young bass can effectively decelerate the expansion of invasive smallmouth bass.     

Implications of a fluctuating fish predator guild on behavior, distribution, and abundance of a shared prey species: the grass shrimp Palaemonetes pugio

In some systems, the identity of a prey species' dominant predator(s) may not be constant over time. In cases in which a prey species exhibits different responses to various predator species, such changes in predator identity may have population-wide consequences. Our goals were to determine (1) whether mortality of and refuge use by the grass shrimp, Palaemonetes pugio, were predator-specific, and (2) how effects of prey size and habitat interacted with predator type. Striped bass (Morone saxatilis) exerted twice as much predation pressure as mummichog (Fundulus heteroclitus), although not equally as great on large (female) and small (male) shrimp. Mummichog, which fed preferentially on large shrimp, forced a partitioning of habitat between the two shrimp size classes. In contrast, large and small shrimp occupied similar habitats when subjected to striped bass, which fed on both size classes equally. Refuge use of grass shrimp depended on predator type. In the presence of mummichog, which occupied shallower depths in the water column than striped bass, shrimp stayed deep and close to structural habitat. Striped bass, which were deeper, caused shrimp to move high in the water column away from structural habitat. When both predators were present, shrimp distribution was similar to that when only striped bass were present, striped bass predation rate was enhanced, and overall mortality was higher than with either predator alone. Results suggest that at times when mummichogs are the dominant predators, large (female) shrimp experience higher predation than small (male) shrimp and are physically separated from their potential mates. When striped bass are more abundant, male and female shrimp may share a similar, shallow, less structure-oriented distribution and be subjected to higher mortality. When both predators are present, mortality rates may be higher still. This predator-, size-, and habitat-specificity of grass shrimp behavior suggests significant population and distribution consequences of fluctuating predator guilds and fluctuating cover of structural habitats in the field.     

Predicting introduction, establishment and potential impacts of smallmouth bass

Aim The introduction of non‐indigenous species has resulted in wide‐ranging ecological and economic impacts. Predictive modelling of the introduction and establishment of non‐indigenous species is imperative to identify areas at high risk of invasion to effectively manage non‐indigenous species and conserve native populations. Smallmouth bass (Micropterus dolomieu), a warm water fish species native to central North America has negatively impacted native fish communities, including cyprinids and salmonid populations, as a result of intentional introductions. We predicted the introduction risk; species establishment based on habitat suitability; identified lakes at high risk of invasion; and finally assessed the consequential impacts on native salmon, trout and cyprinid populations. Location Ontario and British Columbia, Canada. Methods Classification tree and logistic regression models were developed and validated to predict the introduction and establishment of smallmouth bass for thousands of lakes. Results Densely human populated areas and larger lake surface areas successfully identify lakes associated with the introduction of smallmouth bass (introduction model) in British Columbia. Climate, lake morphology and water chemistry variables were the driving environmental parameters to define suitable smallmouth bass habitat (establishment model). A combination of the introduction and establishment model identified 138 lakes that are currently at risk in British Columbia to the introduction and establishment of smallmouth bass. Of these 138 high‐risk lakes, 95% of them contain at least one species of salmon, trout or cyprinid, thereby increasing the potential impact of an invasion by smallmouth bass. Main conclusions Our framework can be applied to other terrestrial and aquatic species to obtain a better understanding of the potential risk posed by a non‐indigenous species to an ecosystem. Furthermore, our methodology can be used to focus management efforts on areas at higher risk (e.g. number of potential releases, more favourable habitats) to control future introductions of non‐indigenous species, thereby conserving native populations.     

Variations in piscivory of invasive largemouth bass <Emphasis Type="Italic">Micropterus salmoides</Emphasis> associated with pond environments

Introductions of non-native predatory fishes can be a major driver of aquatic biodiversity loss. The largemouth bass Micropterus salmoides (L.) has been introduced throughout much of the world, thereafter negatively affecting native faunal communities owing to its predatory impact. To investigate the environmental factors affecting the predatory performance of invasive bass, we examined the stomach contents and habitat characteristics of bass in 15 irrigation farm ponds in northeastern Japan. The food habits of the bass populations differed among the studied ponds: the predominant prey items were fishes among bass in seven of the ponds, whereas aquatic invertebrates (mainly insects and zooplankton) were the predominant taxa in the diets of bass in the eight remaining ponds, with the onset of piscivory related to body size. The results of multivariate analysis indicated that the extent to which the bass consumed fish was positively associated with fish prey abundance and negatively associated with percentage of aquatic vegetation coverage. We suggest that the extent of aquatic vegetation coverage strongly influenced the predation efficiency of bass in the ponds. These findings might be employed to assess a pond ecosystem’s vulnerability to invasive largemouth bass and to reduce the predator’s impact on native fish species by improvements to the habitat.     

Species richness in a model with resource gradient

In order to study the dependence of the species richness on heterogeneity of the habitat, we introduce an extended model of annual plants which combines the features of the island model and of gradient heterogeneity resources. First, we consider a native population of plants living on a square lattice of linear size L. After equilibration of this native population, seeds of several different species j = 2, ... , k of annual plants invade the system; they compete among themselves and the native ones. The system is exposed to a one-dimensional water gradient, and each species is characterised by a tolerance to a surplus of water, τ(j). We study the influences of the properties of the gradient of the resource (GR) on the species richness (SR) present in the system. We have shown that the relation between GR and SR is not straightforward and that several cases could be distinguished: For a large class of control parameters, SR increases linearly with GR. However, when the values of the control parameters are such as to create wide inhabitable regions, the relation between SR and GR ceases to have a monotonic character. We have also demonstrated that the average species richness as a function of the resource availability has a hump shape. Our results can be simply explained within our model and are in agreement with several previous field and theoretical works.     

Herpetofaunal Community Change in Multiple Habitats after Fifteen Years in a Southwest Florida Preserve,USA

Herpetofaunal declines have been documented globally, and southern Florida, USA, is an especially vulnerable region because of high impacts from hydrological perturbations and nonindigenous species. To assess the extent of recent change in herpetofauna community composition, we established a baseline inventory during 1995-97 at a managed preserve in a habitat rich area of southwest Florida, and repeated our sampling methods fifteen years later (2010-11). Nine drift fence arrays were placed in four habitat types: mesic flatwood, mesic hammock, depression marsh, and wet prairie. Trapping occurred daily for one week during 7-8 sampling runs in each period (57 and 49 total sampling days, respectively). Species richness was maintained in mesic hammock habitats but varied in the others. Catch rates of several native species (Anaxyrus terrestris, Lithobates grylio, Anolis carolinensis, Nerodia fasciata) declined significantly. Other native species (Lithobates sphenocephalus, Siren lacertian, and Notophthalmus viridescens piaropicola) that were abundant in 1995-97 declined by greater than 50%. Catch rate of only two species (the nonindigenous Anolis sagrei and the native Diadophis punctatus) increased significantly. Hierarchical cluster analysis indicated similarity within habitat types but significant dissimilarity between sampling periods, confirming shifts in community composition. Analysis of individual species’ contributions to overall similarity across habitats shows a shift from dominance of native species in the 1990s to increased importance of nonindigenous species in 2010-11. Although natural population fluctuations may have influenced differences between the two sampling periods, our results suggest considerable recent change in the structure and composition of this southwest Florida herpetofaunal community. The causes are unknown, but hydrological shifts and ecological impacts of nonindigenous species may have contributed.     

Linking vital rates to invasiveness of a perennial herb

Invaders generally show better individual performance than non-invaders and, therefore, vital rates (survival, growth, fecundity) could potentially be used to predict species invasiveness outside their native range. Comparative studies have usually correlated vital rates with the invasiveness status of species, while few studies have investigated them in relation to population growth rate. Here, I examined the influence of five vital rates (plant establishment, survival, growth, flowering probability, seed production) and their variability (across geographic regions, habitat types, population sizes and population densities) on population growth rate (λ) using data from 37 populations of an invasive, iteroparous herb (Lupinus polyphyllus) in a part of its invaded range in Finland. Variation in vital rates was often related to habitat type and population density. The performance of the populations varied from declining to rapidly increasing independently of habitat type, population size or population density, but differed between regions. The population growth rate increased linearly with plant establishment, and with the survival and growth of vegetative individuals, while the survival of flowering individuals and annual seed production were not related to λ. The vital rates responsible for rapid population growth varied among populations. These findings highlight the importance of both regional and local conditions to plant population dynamics, demonstrating that individual vital rates do not necessarily correlate with λ. Therefore, to understand the role of individual vital rates in a species ability to invade, it is necessary to quantify their effect on population growth rate.     

Spatiotemporal patterns and habitat associations of smallmouth bass (Micropterus dolomieu) invading salmon‐rearing habitat

1. Smallmouth bass (Micropterus dolomieu) have been widely introduced to fresh waters throughout the world to promote recreational fishing opportunities. In the Pacific Northwest (U.S.A.), upstream range expansions of predatory bass, especially into subyearling salmon‐rearing grounds, are of increasing conservation concern, yet have received little scientific inquiry. Understanding the habitat characteristics that influence bass distribution and the timing and extent of bass and salmon overlap will facilitate the development of management strategies that mitigate potential ecological impacts of bass. 2. We employed a spatially continuous sampling design to determine the extent of bass and subyearling Chinook salmon (Oncorhynchus tshawytscha) sympatry in the North Fork John Day River (NFJDR), a free‐flowing river system in the Columbia River Basin that contains an upstream expanding population of non‐native bass. Extensive (i.e. 53 km) surveys were conducted over 2 years and during an early and late summer period of each year, because these seasons provide a strong contrast in the river’s water temperature and flow condition. Classification and regression trees were applied to determine the primary habitat correlates of bass abundance at reach and channel‐unit scales. 3. Our study revealed that bass seasonally occupy up to 22% of the length of the mainstem NFJDR where subyearling Chinook salmon occur, and the primary period of sympatry between these species was in the early summer and not during peak water temperatures in late summer. Where these species co‐occurred, bass occupied 60–76% of channel units used by subyearling Chinook salmon in the early summer and 28–46% of the channel units they occupied in the late summer. Because these rearing salmon were well below the gape limitation of bass, this overlap could result in either direct predation or sublethal effects of bass on subyearling Chinook salmon. The upstream extent of bass increased 10–23 km (2009 and 2010, respectively) as stream temperatures seasonally warmed, but subyearling Chinook salmon were also found farther upstream during this time. 4. Our multiscale analysis suggests that bass were selecting habitat based on antecedent thermal history at a broad scale, and if satisfactory temperature conditions were met, mesoscale habitat features (i.e. channel‐unit type and depth) played an additional role in determining bass abundance. The upstream extent of bass in the late summer corresponded to a high‐gradient geomorphic discontinuity in the NFJDR, which probably hindered further upstream movements of bass. The habitat determinants and upstream extent of bass were largely consistent across years, despite marked differences in the magnitude and timing of spring peak flows prior to bass spawning. 5. The overriding influence of water temperature on smallmouth bass distribution suggests that managers may be able limit future upstream range expansions of bass into salmon‐rearing habitat by concentrating on restoration activities that mitigate climate‐ or land‐use‐related stream warming. These management activities could be prioritised to capitalise on survival bottlenecks in the life history of bass and spatially focused on landscape knick points such as high‐gradient discontinuities to discourage further upstream movements of bass.     

Contrasting Population and Life History Responses of a Young Morph-Pair of European Whitefish to the Invasion of a Specialised Coregonid Competitor,Vendace

Invasions of non-native species represent a global problem of great scientific interest. Here we study in detail the response in population and life history characteristics of closely related native species, with divergent habitat preferences, that are impacted by an invading species over a sufficient time period to allow a new stable state to become established. A time series of 20 years starting at the first occurrence of the invader (vendace Coregonus albula (L.)) allows exploration of the long term population and life history response of two ecologically, morphologically, and genetically different native sympatric morphs (DR- and SR-) of congeneric whitefish C. lavaretus (L.). The whitefish morphs are taxonomically equally related to the invading vendace, but only the planktivorous DR-whitefish share its pelagic niche. We would expect that the ecological differences between the whitefish morphs may be used as a predictor of competitive effects. Vendace exhibited an initial boom-and-bust development, and has continued to fluctuate in density. The responses of the pelagic DR-whitefish were: i) an immediate habitat shift, ii) a subsequent population decline caused by increased annual mortality, and iii) a new stable state at a lower density and apparently relaxed competition. The ecologically more distant benthivorous SR-whitefish also showed significant, but a much more limited response during this process, indicating damped indirect interactions through the food-web. This long-term case-study found that in two native eco-species equally related to the invader, only one of the eco-species was highly affected. Direct competition for resources is obviously important for species interactions, whereas the taxonomic relatedness per se seems to offer little predictive power for invasion effects.     

The Potential Role of Stream Habitat Restoration in Facilitating Salmonid Invasions: A Habitat‐Hydraulic Modeling Approach

Many successful invasions have taken place in systems where harmful disturbance has changed habitat conditions. However, less attention has been paid to the role of habitat restoration, which modifies habitats and thus also has the potential to facilitate invasions. We examined whether in‐stream habitat restorations have the potential to either facilitate or resist invasion by two widely introduced non‐native stream salmonids, Salvelinus fontinalis Mitchill and Oncorhynchus mykiss Walbaum, in Finland. A physical habitat simulation system was used to calculate whether the habitat area for the target species increased or decreased following the restorations. For comparison, we also reported results for four native stream fish species. The simulations showed that the restored streams provided the highest amount of usable habitat area for the native species, particularly for Salmo salar L. and Gottus gobio L. However, it was interesting to note that the restorations significantly increased habitat quality for the two non‐native species, especially at low flows. Nevertheless, the non‐native species had the lowest amount of usable habitat area overall. The modeling results indicated that not only habitat destruction but also habitat restoration could contribute to the spread of non‐native species. Fisheries and wildlife managers should be aware of the possibility, when restoring habitats in order to preserve native ecosystems, that non‐native species could manage to gain a foothold in restored habitats and use them as population sources for further spread. Knowing the widespread negative effect of non‐native species, this risk should not be underestimated.     

Ontogenetic diet shifts and interrupted piscivoryin introduced largemouth bass (Micropterus salmoides)

The ecology of largemouth bass (Micropterus salmoides) is one of the best known for freshwater fish, though largely through studies within its native range (North America). I studied the habitat and diet of a bass population introduced into a Mediterranean lake. The bass displayed strong ontogenetic diet shifts as follows: young‐of‐the‐year <25 mm fed on microcrustaceans; fish 25–75 mm, on amphipods and insects; fish 100–225 mm, on a freshwater shrimp, small fish and insects; fish 250–300 mm, on shrimp or crayfish; and fish >300 mm, on crayfish and large fish. The diet showed several differences from most previous studies: importance of freshwater shrimp instead of insects, low piscivory, and a delay in the ontogenetic shift to piscivory. Moreover, the ontogenetic shift to piscivory was interrupted at 250–300 mm, with consumption of shrimp and crayfish. This interruption of piscivory has been largely unreported and seems a consequence of the size‐structure and species composition of the fish assemblage. A review of the literature suggests that piscivory by largemouth bass might be generally lower in populations introduced outside North America.     

Using Tournament Angler Data to Rapidly Assess the Invasion Status of Alien Sport Fishes (Micropterus spp.) in Southern Africa

Fishes are one of the most commonly introduced aquatic taxa worldwide, and invasive fish species pose threats to biodiversity and ecosystem function in recipient waters. Considerable research efforts have focused on predicting the invasibility of different fish taxa; however, accurate records detailing the establishment and spread of invasive fishes are lacking for large numbers of fish around the globe. In response to these data limitations, a low-cost method of cataloging and quantifying the temporal and spatial status of fish invasions was explored. Specifically, angler catch data derived from competitive bass angling tournaments was used to document the distribution of 66 non-native populations of black bass (Micropterus spp.) in southern Africa. Additionally, catch data from standardized tournament events were used to assess the abundance and growth of non-native bass populations in southern Africa relative to their native distribution (southern and eastern United States). Differences in metrics of catch per unit effort (average number of fish retained per angler per day), daily bag weights (the average weight of fish retained per angler), and average fish weight were assessed using catch data from 14,890 angler days of tournament fishing (11,045 days from South Africa and Zimbabwe; 3,845 days from the United States). No significant differences were found between catch rates, average daily bag weight, or the average fish weight between countries, suggesting that bass populations in southern Africa reach comparable sizes and numbers relative to waters in their native distribution. Given the minimal cost associated with data collection (i.e. records are collected by tournament organizers), the standardized nature of the events, and consistent bias (i.e. selection for the biggest fish in a population), the use of angler catch data represents a novel approach to infer the status and distribution of invasive sport fish.     

Population genetics of pike,genus <Emphasis Type="Italic">Esox</Emphasis> (Actinopterygii,Esocidae), in Northern Italy: evidence for mosaic distribution of native,exotic and introgressed populations

Biomanipulation, or management actions aimed to structure biological communities to achieve certain goals, has often been used in the restoration of aquatic ecosystems. In 2000, The Nature Conservancy acquired the Emiquon Preserve, which included two former Illinois River floodplain lakes, to restore these ecosystems. Restoration included stocking to establish a native fish community commensurate with historical records. Largemouth bass (Micropterus salmoides, bass) were also introduced to control poor water clarity and invasive common carp (Cyprinus carpio, carp). We summarized fish community characteristics and tested whether bass contributed to water clarity maintenance and limited carp during 2007–2014. The fish community was dominated by species stocked in greatest abundance, 13 of 32 species initially stocked have not been collected, and species diversity increased. No carp were observed in bass diets, water clarity declined significantly, and carp relative abundance increased. Increasing water levels during 2008–2009 diffused bass predation potential upon zooplanktivorous fishes and carp and weakened potential trophic cascading interactions. Our findings suggest that water level management, greater stocking of piscivores to maintain predator densities, prevention of gizzard shad (Dorosoma cepedianum) introduction, and/or a more diverse fish community including other native piscivores may be required to achieve long-term restoration goals.     

Modeling of habitat suitability of Asiatic black bear (Ursus thibetanus gedrosianus) in Iran in future

Future changes in climate are imminent and they threat endangered and rare species due to habitat destruction. The Asiatic black bear (Ursus thibetanus gedrosianus) is a rare and vulnerable species whose habitat fragmentation and habitat loss decreased the size of its population significantly. Climate change is another threat to this species that is investigated in this research work. Aiming at this goal, ten species distribution models (SDMs) were applied as helpful tools for evaluating the potential effectiveness of climate change in habitat suitability of Asiatic black bear in Iran. Potential dispersal of Asiatic black bear was modeled as a function of 32 environmental variables for the current time and 2070 for 44 climate change scenarios (CC scenario) of future climate. Our results showed that modeling result depended on type of model. Our results confirmed that one of the greatest threats in the near future for Asiatic black bear was the change of suitable habitat due to climate change. All the CC scenarios showed that migration of this species would be to the north and west areas with higher elevation and that an increase in area would be more than a decrease in area in all scenarios. Recognizing and protecting potential future habitats are of the important activities to conserve this species and identify areas with conservation priority.     

The role of native forest plantations in the conservation of Neotropical birds: the case of the Andean alder

The gradual increase in reforested areas worldwide, as a strategy for mitigating native forest loss, has stressed the need of assessing their real value as habitat for native species. Forest plantations, particularly those based on native species, could be valuable for conservation purposes, especially in heavily fragmented and disturbed ecosystems. We evaluated the value of a monoculture of a native tree species, the Andean alder (Alnus acuminata), for the conservation of avifauna in the Central Andes region, which is considered a bird species diversity hotspot but also suffers from high anthropogenic disturbance levels. Our results suggest that alder plantations are valuable for conservation from three points of view: (1) they have similar or greater bird species richness and abundance than secondary native forests; (2) low community similarities are found between this type of forest compared to secondary forest stands (with 27 species exclusive to alder plantations); and (3) three near threatened species (Odontophorus hyperythrus, Eriocnemis derbyi, and Cyanolyca viridicyanus). Further, 27 out of the 85 species found at the alder plantations were of least concern but showing decreasing population trends. While forest plantations do not replace native forests, they offer habitat for many bird species, some of them being of conservation concern (i.e., included in an IUCN threat category) or with decreasing populations. Hence establishing native species plantations among native forest remnants – especially in heavily fragmented landscapes – could have a positive effect in the conservation of threatened avifauna.