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A field guide to freshwater fishes of North America north of Mexico. 2nd edition

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... North America and inhabits a wide range of habitats (Page and Burr 2011;TNACI FIN 2018). Lepomis megalotis (+ 3 sites) is distributed widely across central North America and inhabits pools with structure in small to medium sized rivers (Page and Burr 2011;TNACI FIN 2018). ...
... North America and inhabits a wide range of habitats (Page and Burr 2011;TNACI FIN 2018). Lepomis megalotis (+ 3 sites) is distributed widely across central North America and inhabits pools with structure in small to medium sized rivers (Page and Burr 2011;TNACI FIN 2018). Semotilus atromaculatus (+ 4 sites) is distributed widely throughout central and eastern North America and typically inhabits rocky pools and headwaters of small rivers (Page and Burr 2011;TNACI FIN 2018). ...
... Lepomis megalotis (+ 3 sites) is distributed widely across central North America and inhabits pools with structure in small to medium sized rivers (Page and Burr 2011;TNACI FIN 2018). Semotilus atromaculatus (+ 4 sites) is distributed widely throughout central and eastern North America and typically inhabits rocky pools and headwaters of small rivers (Page and Burr 2011;TNACI FIN 2018). A majority of these species that added site occurrence prefer slow-flowing pools of medium-sized rivers. ...
... Darters (Etheostoma spp.; Percidae) comprise a diverse group of North American freshwater fishes that vary in the degree and composition of male nuptial coloration (Page & Burr 2011). Male nuptial colors are most vividly expressed on the body and fins during the spring-to-summer spawning seasons. ...
... The majority of species possess two classes of coloration, as determined by reflectance spectrophotometry. The blue/green class is characterized by reflectance spectra with a unimodal peak in the 469-538 nm range, and the red/orange class is characterized by the stepshaped reflectance spectra of carotenoid-based colors, with a midpoint reflectance (k R50 ) = 532-678 nm Page & Burr 2011;Ciccotto et al. 2014). Both blue/green and red/orange colors are pigment-based, with blue tissues containing a chromoprotein pigment and red tissues containing a carotenoid pigment Zhou et al. 2014). ...
... A single specimen of Percina peltata, a species of darter outside of our focal genus, caught in 2013 from the Matta River in Spotsylvania County, Virginia, was used for the molds. The individual's total length was 71 mm, which was close to the average maximum total length of the focal species (75.9 mm) based on length data from Page & Burr (2011). A single specimen was used to control for size and body shape that was not skewed toward any particular species. ...
Article
Sexual selection theory predicts that preferences in both sexes select for the elaboration of male nuptial coloration, with empirical evidence supporting these predictions. Empirical studies are often limited in their taxonomic inclusiveness, however, and typically do not examine how male and female preferences contribute to macroevolutionary patterns of male color variation across multiple lineages in a clade. This study examined color preferences in a group of dichromatic freshwater fishes known as darters (genus Etheostoma) that vary in the presence of male coloration. The strengths of attraction to black, blue, gray, and red models were tested in females of 18 species, in addition to males of five species. We found a positive association between the presence of red or orange on the body and the amount of time associating with red models, suggesting color variation is at least in part due to variation in female preferences between species. Males also spent more time associating with colors that most closely resembled conspecifics, suggesting that preferential responses to color in males also can contribute to the diversity of nuptial coloration in darters.
... Target species.-The Iowa Darter is a widespread benthic fish with a range stretching roughly from the Appalachian Mountains west to the Rocky Mountains and Hudson Bay south to the 40°N parallel (Page and Burr, 2011). Iowa Darters inhabit the vegetated areas of glacial lakes and pools of clear, low gradient streams (Smith, 1979), but also use medium-sized rivers, oxbow lakes, and impounded areas of large rivers (Becker, 1983). ...
... Site-specific data collected from our field samples provide further information on the localized indicators of Iowa Darter presence. The 2 fish species most associ-ated with Iowa Darters, Central Mudminnow and Brook Stickleback, share a similar Illinois and range-wide distributions (Smith, 1979;Page and Burr, 2011). Both species occur in streams which are cooler in the summer months (Smith, 1979). ...
... Each observed madtom was counted and recorded. Each madtom species was considered ecologically equivalent, due to similar habitat preferences (Page and Burr 2011). Therefore, there was no discrimination of madtom species when an individual was encountered. ...
... We also compared our data for the Florida population with what has been reported for E. f. fusiforme when comparable data were available. Page and Burr (2011). The red line represents the approximate boundary between E. f. fusiforme in the northern part of the range and E. f. barratti in the southern part. ...
... Bluegill-Bluegill are abundant in freshwater habitats throughout Florida, and their tendency to inhabit low-salinity habitats in coastal rivers has been recognized since the 19 th century (Goode 1879a;Hoyer and Canfield 1994;Page and Burr 2011). Our dataset contains 2,157 Bluegill, with most collected upstream of river kilometer 8 (Table 1). ...
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Abundances and locations of maximum abundance for eight low-salinity resident species in the Alafia River were investigated in an attempt to find appropriate indicator species to assess the impact of Tampa Bay Water’s Water Use Permit on the Alafia River. We visually assessed trends in abundance and location over the course of 12 wet and 12 dry seasons from 2000 to 2012 and calculated regressions between abundance and location over these same seasons. Based on these analyses, Bluegill and Striped Mojarra would be the top candidates for monitoring in relation to abundance, and Bluegill, Striped Mojarra, and Rainwater Killifish would be the top candidates for monitoring in relation to center of maximum abundance. The low-salinity habitat in the lower Alafia River represents a persistent ecological component of the estuary. Some species occur in these oligohaline to freshwater tidal river reaches for most, if not all, of their lives. Other economically transient taxa (e.g., Centropomus undecimalis or Common Snook and Sciaenops ocellatus or Red Drum) use low-salinity habitat for critical portions of their early life history. Re-stratifying the HBMP nekton sampling design to emphasize this habitat component would likely improve the utility of the abundance and distribution metrics for the low salinity species identified as top candidates for monitoring (Bluegill, Striped Mojarra, and Rainwater Killifish). Re-allocating a higher percentage of the samples to low salinity habitats would reduce the variability in the IOAs and, thereby, refine the ability to relate inflow with the desired metric. Emphasizing the species that inhabit low-salinity habitats would provide a valuable tool and metric for the preservation of this habitat type in the Alafia River.
... Despite a large amount of research on alarm behavior in fishes (Chivers and Smith 1998, Ferrari et al. 2010, Smith 1992, it remains unclear in most species whether chondroitin acts as a component of alarm cues, and if so, what response it elicits. The goal of our study was to investigate the ability of chondroitin to elicit behavior consistent with an alarm response in Fundulus catenatus (Storer) (Northern Studfish), a stream fish widely distributed in the Ohio and Mississippi River drainages (Page and Burr 2011). Although the species that prey upon Northern Studfish in the wild are not well documented, potential predators include Alarm responses to various chemical stimuli have been well documented in stream fishes. ...
Article
The evolution of organismal cue-response systems can allow for an effective behavioral reaction to various environmental signals. In aquatic habitats, the reception of certain chemical cues can increase individual fitness of organisms by serving as an indicator of predation threat. In some fish species, damage to an individual's epidermal cells causes release of a substance that functions as an alarm cue and consequently initiates defense responses in neighboring prey. Recent research on the chemical makeup of the substance that elicits an anti-predator response in Danio rerio (Hamilton) (Zebrafish) revealed that chondroitin fragments were a key component in this substance. The goal of our study was to investigate the ability of chondroitin to elicit an alarm response in Fundulus catenatus (Storer) (Northern Studfish). This species is a small-bodied killifish native to southeastern to south-central USA and is associated with topwater habitats near aquatic and/or overhanging vegetation. We hypothesized that reduced movement and/or a change in position in the water column would be a likely response of the Northern Studfish to chondroitin. We experimentally observed Northern Studfish behavior before and after the addition of chondroitin and a control substance, and compared the fishes' behavioral responses. Our results show that the Northern Studfish that were exposed to chondroitin tended to reduce their movement by sevenfold and were more likely to move to the bottom of the aquarium relative to the control group, suggesting that chondroitin potentially serves as an alarm-cue component in this species. Our study represents the first demonstration of Northern Studfish response to a chemical cue and the first time that chondroitin sulfate has been shown to elicit a component of alarm behavior in a stream fish. We discuss our findings in relation to potential uses of chondroitin as an alarm cue in the conservation of imperiled stream fishes.
... Fishes collected but not vouchered were returned without harm to their native habitat. Nomenclature follows Page and Burr (2011). In addition, the Wisconsin Department of Natural Resources' (WDNR) Fish Mapper was accessed (http://infotrek.er.usgs.gov ...
Article
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The redside dace Clinostomus elongatus is a small, laterally compressed cyprinid commonly found in small streams with moderate to high gradients, clear and cool water, and substrates of clean gravel, sand, or bedrock. Fish surveys in Winnebago County, Illinois, and Rock County, Wisconsin, conducted from 1997-2000 and 2010-2011 discovered the dace at a single site in Illinois in East Fork Raccoon Creek (Pecatonica River – Rock River Drainage). This is the first documented record of this species in Illinois and raises the known total of state native fishes to 192. Based on these surveys, C. elongatus is expected to periodically occur in the Illinois portion of the Raccoon Creek basin, and therefore should be considered a peripheral species in Illinois.
... Amazon mollies and their parent species are distributed primarily along coastal Gulf of Mexico. Amazon mollies are sympatric with sailfin mollies from south-eastern Texas into northern Mexico near Rio Tuxpan [21]. Atlantic mollies are sympatric with Amazon mollies from north of Ciudad Tuxpan to Rio San Fernando, Mexico. ...
Article
Much is known about the role of hormones in the regulation of vertebrate mating behavior, including receptivity, and several components of mate choice. Hormones may modulate reproductive behavior in such a way to increase or decrease the individual's motivation, and therefore hormones may be important in mediating behavior associated with reproductive isolation. The mating complex of the all female gynogenetic Amazon mollies, Poecilia formosa, and their parental species (sailfin mollies, P. latipinna, and Atlantic mollies, P. mexicana) is a model system for studying ultimate mechanisms of species recognition. However, proximate mechanisms, such as variation in hormone levels, and the effect of hormones on sperm production have not been extensively examined. We predict that one or more of the sex steroid hormones in teleost fish (11-ketotestosterone (KT), testosterone (T), and estradiol (E)) will play a role in species recognition (during mate choice and/or sperm priming) for Atlantic mollies (the maternal parental species) that are sympatric with Amazon mollies. We sequentially paired male Atlantic mollies with female conspecifics and Amazon mollies and obtained water-borne hormone samples before and after mating for all fish. We measured circulating KT, T, and E from the water samples. Although we did not find an overall KT response to mating with conspecifics as has been found previously in sailfin mollies, male Atlantic mollies that mated more with conspecific females had lower postmating T levels. Additionally, males attempted to mate more with conspecific females that had lower postmating E levels, but attempted to mate more with Amazon mollies that had higher postmating KT levels. We also examined the effect of KT on sperm priming (a mechanism of premating mate choice), and found that KT levels of male Atlantic mollies prior to mating are correlated with the sperm priming response when males were paired with conspecific females, but this correlation was not found when males were paired with Amazon mollies. Our results indicate that male mating behavior is affecting or responding to both male and female hormones, but that the hormones alone are not playing a role in species recognition. Male Atlantic mollies may not discriminate against Amazon mollies as strongly as male sailfin mollies because Amazon mollies resemble their maternal parental species more than their paternal species.
Article
This datasheet on Pimephales vigilax covers Identity, Overview, Distribution, Dispersal, Diagnosis, Biology & Ecology, Environmental Requirements, Natural Enemies, Impacts, Uses, Prevention/Control, Further Information.
Article
Determining the occurrence and site occupancy of rare and endangered species can be challenging, particularly without causing harm or stress to the species of concern. Environmental DNA (eDNA) detection was used to assess habitat occupancy by spotted gar (Lepisosteus oculatus), which is federally listed as Threatened in Canada, with known occurrences limited to a small number of locations in southern Ontario. Quantitative polymerase chain reaction (qPCR) assays were developed to detect spotted gar eDNA, which was detected in all but one previously recorded location. The eDNA method was shown to be more effective than traditional netting for detecting spotted gar habitat use. The use of qPCR allowed for quantification of substantial variation in detection strength (copy number) among replicate eDNA samples, with implications for establishing sampling designs for detection and surveillance. The use of eDNA for detection and monitoring of aquatic species of conservation concern shows great potential as a non-invasive method for assessing species occurrences and habitat occupancy, as well as for informing targeted sampling by conventional capture methods. Copyright
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Mediante el proyecto Aspectos biológicos e impacto socio-económico de los plecos del género Pterygoplichthys y dos cíclidos no nativos en el sistema fluvio lagunar deltaico Río Palizada, en el Área Natural Protegida Laguna de Términos, Campeche, se logrará obtener un registro actualizado del impacto de especies invasoras en la región desde el punto de vista biológico y socioeconómico, destacándose que efectos pudieran tener estas especies introducidas sobre la distribución y abundancia de las especies nativas y en qué forma ha repercutido esto en la pesquería como fuente de sustento de los habitantes de la localidad. Se realizarán estudios de reproducción como indicadores de la adaptación y éxito de las especies en al hábitat. Además se contará con un registro fotográfico de las especies de peces del sistema.
Article
Belonesox belizanus Kner (Teleostei: Poeciliidae) is a wide-spread livebearing species that occurs on the Atlantic Slope of Central America from southern Mexico to northern Costa Rica. Previous work has noted morphological variation within the species, and recognized two subspecies: Belonesox belizanus belizanus and Belonesox belizanus maxillosus. We used 1122 bp of cytochrome b and 617 bp of S7-1 DNA to conduct a phylogeographical study of Belonesox, aiming to examine the genetic distinctiveness of these taxa and other populations of Belonesox throughout the range. Bayesian phylogenetic and haplotype analyses indicated that B. b. maxillosus is not distinctive from other northern populations of Belonesox. However, a distinct phylogeographical break is evident near the Rio Grande in southern Belize. One clade comprises the putative B. b. maxillosus and all populations sampled north of the Rio Grande. The other clade comprises the Rio Grande and all populations south thereof. Fossil-calibrated divergence time estimates suggest that isolation of the northern and southern lineages of Belonesox occurred approximately 14.1 Mya. The phylogeographical structure recovered in the present study is interesting, considering that relatively few studies have examined molecular variation across this portion of Middle America in a time-calibrated framework. Furthermore, the present study suggests that more work is needed to adequately understand the factors that have shaped diversity of this region. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 848–860.
Article
We describe 13 diploid microsatellite markers for the North American paddlefish (Polyodon spathula, Polyodontidae), a declining species that supports a significant recreational fishery and, because of its antiquity, is unusually important in the effort to preserve biodiversity. We tested these markers on 30 individuals from a mainstream reservoir of the Neosho River in northeastern Oklahoma, USA and provide summary statistics on population variability. Eleven loci yielded two to six alleles per locus with mean heterozygosities of 0.533 (observed) and 0.555 (expected). These markers contribute to the availability of markers for programs aimed at monitoring and managing the genetic resources of P. spathula and related Acipenseriform taxa.
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We describe eight tetra-nucleotide microsatellite markers for the leopard darter (Percina pantherina), a federally threatened percid fish endemic to Oklahoma and Arkansas. We tested these markers on 42 individuals from two localities and provide summary statistics on population variability. Eight loci yielded 2–12 alleles per locus. These markers contribute to the availability of markers for programs aimed at monitoring and managing the genetic resources of P. pantherina and related taxa.
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In the present study we examined and compared external morphology as well as osteological characters of two species of the genus Ameiurus (Teleostei, Ictaluridae): the black bullhead (Ameiurus melas) and brown bullhead (Ameiurus nebulosus), two catfish species that are invasive to Europe. In total 83 (53 and 30) individuals were captured in the Czech Republic and the Slovak Republic and further analysed. For genetic screening of both Ameiurus species were chosen three DNA regions: part of nuclear Recombination activating gene 1 (RAG-1), mitochondrial gene for cytochrome b (cyt b) and mitochondrial sequence which includes 12S and 16S ribosomal RNA genes. The results presented in this paper concern specific osteological characteristics (original scheme of pectoral spine and pectoral girdle) used for the determination purposes and also verification that mathematical multivariate methods for external morphology analysis can be used for the determination of Ameiurus species. The summary of 80 out of 83 fish (96.4 %) was correctly classified using the discriminant analysis.
Article
Sexual dimorphism is hypothesized to be the result of differential selection pressures between the sexes. Dimorphic traits can serve as indicators of mate quality, altering mate preferences in the opposite sex in favor of a conspicuous trait. Common indicators of mate quality include color and size, with traditional assumptions and evidence predicting a preference for more colorful and/or larger sized mates in many species. Both male and female preferences for more colorful and larger mates within a species are rarely examined simultaneously, however. We examined a sexually dichromatic freshwater fish, Percina roanoka and found that male coloration is positively correlated with size, suggesting color may function as an indicator of viability. We tested preferences for coloration and size in both sexes in a dichotomous mate choice setup in which only visual signals were exchanged. Neither females nor males exhibited a color or size preference in individuals of the opposite sex. Visual cues alone therefore appear to be insufficient to elicit a significant preference in both sexes of this species. Male coloration in P. roanoka does not appear to be driven solely by female preference.
Article
Countries develop “Red Lists” of their endangered freshwater fish species. At the same time, international bodies such as the International Union for the Conservation of Nature (IUCN) recognize fishes threatened at a global scale. A comparison between red listed fish species in 12 countries with their IUCN ranks showed that many of the species that appear on country lists are not recognized similarly by IUCN, and vice versa. Disagreement arises as a result of missing assessments, misapplication of data or protocols, focus on local vs. global status, emphasis on subspecies vs. species, acceptance of simple rarity as a metric of imperilment for marginal populations, failure or inability of countries to follow IUCN protocols, lack of communication, disagreement on the status of species, and legal wrangling, among others. Regardless, disagreement can be used to justify delaying action to protect species and undermines the credibility of those engaged in preservation efforts. These problems could be diminished via greater communication and respect between national and international entities, active conflict resolution, and creation of an IUCN category that recognizes species protected by national legislation via a “TH(N) (Nationally Threatened)” rank, regardless of adherence to IUCN protocols.
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1.The swordtail Xiphophorus hellerii is a popular ornamental freshwater fish that occurs as an introduced species in the aquatic habitats of at least 31 countries. Although introduced populations are found in other Australian states, the only known Western Australian population occurs in the Irwin River (29°15′S).2.The biology of X. hellerii in the Irwin River in south-western Australia is described from four seasonal samples, collected by seine net, between spring 2002 and winter 2003.3.Pregnant females were collected in all seasonal samples, though juveniles were absent in spring, implying that juvenile mortality during late winter is high. Although mean length of pregnant females (38.7 mm) and mean gonadosomatic index (GSI) (14.7) were similar to reported data for X. hellerii populations in Queensland, mean fecundity was markedly lower in Western Australia, i.e. 34.1, cf. 60.15.4.Logistic analysis of the percentage of female and male X. hellerii with developing and mature gonads predicted that the length at which 50% of the sexes mature was 30.8 and 31.5 mm SL, respectively. The sex ratios of females to males did not differ statistically from a ratio of 2:1.5.The diet of all X. hellerii size classes was omnivorous (primarily vegetal matter/algae), although a significant difference was observed between the diet of juveniles and that of the two larger size classes (i.e. juveniles consumed greater quantities of aquatic invertebrates).6.A melanic polymorphism (i.e. pigmented caudal peduncle and fin) was observed in approximately 5% of X. hellerii collected.7.If released, the range of X. hellerii is likely to expand in anthropogenically modified habitats in tropical and temperate latitudes of Western Australia. Potential ecological impacts on indigenous fishes may be magnified owing to the depauperate nature of the endemic ichthyofauna including a lack of predators. Copyright © 2011 John Wiley & Sons, Ltd.
Article
In this study, we isolated and characterized nine polymorphic trinucleotide microsatellites (CAG and CCT) from the crucian carp (Carassius auratus). The number of alleles per locus ranged from two to six. Five loci showed a significantly excess homozygosity, and a genetic linkage between CAL0102 and CAL0495 was strongly suggested. Our results confirmed the triploidy of Korean individuals, and the microsatellites were found to be useful for analysing the allelic state of the polyploid crucian carp.
Article
Assessing the passage of aquatic organisms through culvert road crossings has become increasingly common in efforts to restore stream habitat. Several federal and state agencies and local stakeholders have adopted assessment approaches based on literature-derived criteria for culvert impassability. However, criteria differ and are typically specific to larger-bodied fishes. In an analysis to prioritize culverts for remediation to benefit imperiled, small-bodied fishes in the Upper Coosa River system in the southeastern United States, we assessed the sensitivity of prioritization to the use of differing but plausible criteria for culvert impassability. Using measurements at 256 road crossings, we assessed culvert impassability using four alternative criteria sets represented in Bayesian belief networks. Two criteria sets scored culverts as either passable or impassable based on alternative thresholds of culvert characteristics (outlet elevation, baseflow water velocity). Two additional criteria sets incorporated uncertainty concerning ability of small-bodied fishes to pass through culverts and estimated a probability of culvert impassability. To prioritize culverts for remediation, we combined estimated culvert impassability with culvert position in the stream network relative to other barriers to compute prospective gain in connected stream habitat for the target fish species. Although four culverts ranked highly for remediation regardless of which criteria were used to assess impassability, other culverts differed widely in priority depending on criteria. Our results emphasize the value of explicitly incorporating uncertainty into criteria underlying remediation decisions. Comparing outcomes among alternative, plausible criteria may also help to identify research most needed to narrow management uncertainty.
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Amphibian secondary metabolites are well known chemically, but their ecological functions are poorly understood--even for well-studied species. For example, the eastern newt (Notophthalmus viridescens) is a well known secretor of tetrodotoxin (TTX), with this compound hypothesized to facilitate this salamander's coexistence with a variety of aquatic consumers across the eastern United States. However, this assumption of chemical defense is primarily based on observational data with low replication against only a few predator types. Therefore, we tested the hypothesis that N. viridescens is chemically defended against co-occurring fishes, invertebrates, and amphibian generalist predators and that this defense confers high survivorship when newts are transplanted into both fish-containing and fishless habitats. We found that adult eastern newts were unpalatable to predatory fishes (Micropterus salmoides, Lepomis macrochirus) and a crayfish (Procambarus clarkii), but were readily consumed by bullfrogs (Lithobates catesbeianus). The eggs and neonate larvae were also unpalatable to fish (L. macrochirus). Bioassay-guided fractionation confirmed that deterrence is chemical and that ecologically relevant concentrations of TTX would deter feeding. Despite predatory fishes rejecting eastern newts in laboratory assays, field experiments demonstrated that tethered newts suffered high rates of predation in fish-containing ponds. We suggest that this may be due to predation by amphibians (frogs) and reptiles (turtles) that co-occur with fishes rather than from fishes directly. Fishes suppress invertebrate consumers that prey on bullfrog larvae, leading to higher bullfrog densities in fish containing ponds and thus considerable consumption of newts due to bullfrog tolerance of newt chemical defenses. Amphibian chemical defenses, and consumer responses to them, may be more complex and indirect than previously appreciated.
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Accurate establishment of baseline conditions is critical to successful management and habitat restoration. We demonstrate the ability to robustly estimate historical fish community composition and assess the current status of the urbanized Barton Creek watershed in central Texas, U.S.A. Fish species were surveyed in 2008 and the resulting data compared to three sources of fish occurrence information: (i) historical records from a museum specimen database and literature searches; (ii) a nearly identical survey conducted 15 years earlier; and (iii) a modeled historical community constructed with species distribution models (SDMs). This holistic approach, and especially the application of SDMs, allowed us to discover that the fish community in Barton Creek was more diverse than the historical data and survey methods alone indicated. Sixteen native species with high modeled probability of occurrence within the watershed were not found in the 2008 survey, seven of these were not found in either survey or in any of the historical collection records. Our approach allowed us to more rigorously establish the true baseline for the pre-development fish fauna and then to more accurately assess trends and develop hypotheses regarding factors driving current fish community composition to better inform management decisions and future restoration efforts. Smaller, urbanized freshwater systems, like Barton Creek, typically have a relatively poor historical biodiversity inventory coupled with long histories of alteration, and thus there is a propensity for land managers and researchers to apply inaccurate baseline standards. Our methods provide a way around that limitation by using SDMs derived from larger and richer biodiversity databases of a broader geographic scope. Broadly applied, we propose that this technique has potential to overcome limitations of popular bioassessment metrics (e.g., IBI) to become a versatile and robust management tool for determining status of freshwater biotic communities.
Article
We studied the role of the lateral line system for detection and discrimination of dipole stimuli in the oscar, Astronotus ocellatus (Family Cichlidae), and determined detection thresholds in still water and frequency discrimination capabilities in still and turbulent water. Average detection threshold of six animals for a 100-Hz dipole stimulus was 0.0059 μm peak-to-peak water displacement at the surface of the fish. After inactivation of the neuromast receptor organs of the lateral line system with the antibiotic streptomycin, dipole detection was reduced, but recovered within 2-4 weeks. This suggests that the oscar relied strongly on hydrodynamic information received by the lateral line system. Five oscars learned to discriminate a 100-Hz stimulus from 70 Hz and lower frequencies. When turbulence was introduced into the experimental tank, fish were still able to discriminate 100 Hz from frequencies 70 Hz and lower indicating that frequency discrimination mediated by the lateral line system was not reduced in turbulent water.
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