Nongame Conservation Section

Social Circle, Georgia, United States

Nongame Conservation Section

Social Circle, Georgia, United States
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Albanese B.,Nongame Conservation Section | Owers K.A.,University of Groningen | Weiler D.A.,Nongame Conservation Section | Pruitt W.,University of Georgia
Southeastern Naturalist | Year: 2011

Abstract There is an ongoing need to monitor the status of imperiled fishes in the southeastern United States using effective methods. Visual surveys minimize harm to target species, but few studies have specifically examined their effectiveness compared to other methods or accounted for imperfect species detection. We used snorkel surveys to estimate detection probability and site occupancy for rare fishes in the Toccoa River system of north Georgia. We also carried out backpack electrofishing at a subset of sites to compare detection probabilities for both methods. The probability of detecting Percina aurantiaca (Tangerine Darter) and Etheostoma vulneratum (Wounded Darter) while snorkeling was relatively high, averaging 30% and 22%, respectively, and nave and estimated occupancy rates (i.e., corrected for incomplete species detection) were almost identical for both species. The probability of detecting Erimystax insignis (Blotched Chub) while snorkeling was relatively low (9%), and their estimated occupancy rate (86%) was much higher than we detected in our survey. Detection was negatively related to depth and substrate size for Blotched Chub and positively related to depth for Tangerine Darter. Compared to snorkeling, the probability of detecting a species while backpack electrofishing was higher for Wounded Darter (40%) and comparable for Blotched Chub (11%). Tangerine Darter, however, were never captured while electrofishing even though they occurred at all four sites where both methods were used. Our study demonstrates the successful use of snorkel sampling to estimate occupancy rates of rare fishes in a large, clear southeastern river and illustrates the importance of accounting for imperfect species detection.

Rush S.,University of Windsor | Klaus N.,Nongame Conservation Section | Keyes T.,Nongame Conservation Section | Petrick J.,U.S. Department of Agriculture | Cooper R.,University of Georgia
Forest Ecology and Management | Year: 2012

Fire is frequently applied as a management tool on both public and private lands. However, in some ecosystems there is little information about bird species' responses to these fire programs. In 2004 we measured habitat characteristics and conducted point counts in 12 burned sites and four unburned sites in the Chattahoochee National Forest of northern Georgia. Burns were categorized by severity (low, medium, or high) and time since fire (1-2 or 3-6. years). The basal area of snags, shrub stem density and percent canopy cover were similar among all treatments except high severity. Otherwise, fire severity had limited impacts on measured habitat characteristics. Following fires the densities of early-succession species such as eastern towhee (Pipilo erythropthalmus) and indigo bunting (Passerina cyanea) were greatest in areas of higher fire severity. A ground-nesting species (ovenbird [. Seiurus aurocapilla]) was less abundant in burned sites and the density of a shrub nesting species, the hooded warbler (Setophaga citrine) was greatest in areas that received low severity fires. Scarlet tanager (Piranga olivacea), tufted titmouse (Baeolophus bicolor), red-eyed vireo (Vireo olivaceus), black-throated green warbler (Setophaga virens), and black-and-white warbler (Mniotilta varia) had similar densities among all burn severities and showed no relationships with time since fire. Low and medium severity fires provided few benefits for most bird species. When conditions allow for their application, severe fires may be considered as a useful and historically appropriate management tool for some high-priority bird species in the southern Appalachian Mountains. © 2011 Elsevier B.V.

Shea C.P.,University of Georgia | Peterson J.T.,University of Georgia | Peterson J.T.,U.S. Geological Survey | Wisniewski J.M.,Nongame Conservation Section | Johnson N.A.,University of Florida
Journal of the North American Benthological Society | Year: 2011

Surveys of freshwater mussel populations are used frequently to inform conservation decisions by providing information about the status and distribution of species. It is generally accepted that not all mussels or species are collected during surveys, and incomplete detection of individuals and species can bias data and can affect inferences. However, considerably less attention has been given to the potential effects of species misidentification. To evaluate the prevalence of and potential reasons for species misidentification, we conducted a laboratory-based identification exercise and quantified the relationships between mussel species characteristics, observer experience, and misidentification rate. We estimated that misidentification was fairly common, with rates averaging 27% across all species and ranging from 0 to 56%, and was related to mussel shell characteristics and observer experience. Most notably, species with shell texturing were 6.09× less likely than smooth-shelled species to be misidentified. Misidentification rates declined with observer experience, but for many species the risk of misidentification averaged >10% even for observers with moderate levels of experience (5-6 y). In addition, misidentification rates among observers showed substantial variability after controlling for experience. Our results suggest that species misidentification may be common in field surveys of freshwater mussels and could potentially bias estimates of population status and trends. Misidentification rates possibly could be reduced through use of regional workshops, testing and certification programs, and the availability of archived specimens and tissue samples in museum collections. © 2011 The North American Benthological Society.

Wisniewski J.M.,Nongame Conservation Section | Abbott S.,U.S. Fish and Wildlife Service | Gascho Landis A.M.,New York University
River Research and Applications | Year: 2015

Recurrent and prolonged droughts, coupled with increased water resource demand, threaten freshwater mussel populations through stream drying and water quality degradation. Augmentation of stream discharge was proposed as a short-term strategy to maintain adequate streamflows and water quality in reaches with important freshwater mussel populations during exceptionally low flow periods. We investigated the effects of water augmentation on seven freshwater mussel species in a small creek between 2011 and 2014. Using capture-mark-recapture methods, we monitored mussel populations in a control reach upstream of an augmentation outlet and two reaches immediately downstream of an augmentation outlet. Water quality measurements during our study indicated that augmentation improved water temperature and dissolved oxygen conditions during low flow periods. For all mussel species, apparent survival was positively related to minimum streamflows and declined precipitously as streamflows decreased. However, mean apparent survival between sampling occasions was high among all species but did not differ among treatment units, suggesting that flow augmentation rates in this study were insufficient for abating the effects of basin-wide reductions in streamflow. Temporary emigration differed among study reaches but did not support hypothesized relationships because it increased with stream stage and was highest in an augmented reach. This suggests that streamflows did not drop below thresholds, which invoked burrowing as a response to decreased streamflows. Streamflow augmentation may be a viable short-term mussel conservation strategy in small streams but will likely require higher augmentation volume capacity than evaluated during our study. © 2015 John Wiley & Sons, Ltd.

Peterson J.T.,U.S. Geological Survey | Peterson J.T.,Oregon State University | Wisniewski J.M.,Nongame Conservation Section | Shea C.P.,University of Georgia | Rhett Jackson C.,University of Georgia
Environmental Management | Year: 2011

The southeastern United States has experienced severe, recurrent drought, rapid human population growth, and increasing agricultural irrigation during recent decades, resulting in greater demand for the water resources. During the same time period, freshwater mussels (Unioniformes) in the region have experienced substantial population declines. Consequently, there is growing interest in determining how mussel population declines are related to activities associated with water resource development. Determining the causes of mussel population declines requires, in part, an understanding of the factors influencing mussel population dynamics. We developed Pradel reverse-time, tag-recapture models to estimate survival, recruitment, and population growth rates for three federally endangered mussel species in the Apalachicola- Chattahoochee-Flint River Basin, Georgia. The models were parameterized using mussel tag-recapture data collected over five consecutive years from Sawhatchee Creek, located in southwestern Georgia. Model estimates indicated that mussel survival was strongly and negatively related to high flows during the summer, whereas recruitment was strongly and positively related to flows during the spring and summer. Using these models, we simulated mussel population dynamics under historic (1940-1969) and current (1980-2008) flow regimes and under increasing levels of water use to evaluate the relative effectiveness of alternative minimum flow regulations. The simulations indicated that the probability of simulated mussel population extinction was at least 8 times greater under current hydrologic regimes. In addition, simulations of mussel extinction under varying levels of water use indicated that the relative risk of extinction increased with increased water use across a range of minimum flow regulations. The simulation results also indicated that our estimates of the effects of water use on mussel extinction were influenced by the assumptions about the dynamics of the system, highlighting the need for further study of mussel population dynamics. © 2011 Springer Science+Business Media, LLC (outside the USA).

Luo Y.,Auburn University | Luo Y.,Shanghai Ocean University | Li C.,Auburn University | Landis A.G.,Nongame Conservation Section | And 3 more authors.
PLoS ONE | Year: 2014

The southeastern US has experienced recurrent drought during recent decades. Increasing demand for water, as precipitation decreases, exacerbates stress on the aquatic biota of the Southeast: a global hotspot for freshwater mussel, crayfish, and fish diversity. Freshwater unionid mussels are ideal candidates to study linkages between ecophysiological and behavioral responses to drought. Previous work on co-occurring mussel species suggests a coupling of physiology and behavior along a gradient ranging from intolerant species such as Pyganodon grandis (giant floater) that track receding waters and rarely burrow in the substrates to tolerant species such as Uniomerus tetralasmus (pondhorn) that rarely track receding waters, but readily burrow into the drying sediments. We utilized a next-generation sequencing-based RNA-Seq approach to examine heat/desiccation-induced transcriptomic profiles of these two species in order to identify linkages between patterns of gene expression, physiology and behavior. Sequencing produced over 425 million 100 bp reads. Using the de novo assembly package Trinity, we assembled the short reads into 321,250 contigs from giant floater (average length 835 bp) and 385,735 contigs from pondhorn (average length 929 bp). BLAST-based annotation and gene expression analysis revealed 2,832 differentially expressed genes in giant floater and 2,758 differentially expressed genes in pondhorn. Trancriptomic responses included changes in molecular chaperones, oxidative stress profiles, cell cycling, energy metabolism, immunity, and cytoskeletal rearrangements. Comparative analyses between species indicated significantly higher induction of molecular chaperones and cytoskeletal elements in the intolerant P. grandis as well as important differences in genes regulating apoptosis and immunity. © 2014 Luo et al.

Meador J.R.,University of Georgia | Peterson J.T.,University of Georgia | Peterson J.T.,Oregon State University | Wisniewski J.M.,Nongame Conservation Section
Journal of the North American Benthological Society | Year: 2011

The decline of freshwater mussels in the southeastern US emphasizes the need to evaluate the current status of mussel populations. We used the Robust Design, which is a capture-recapture sampling design, to estimate demographic parameters (apparent survival and temporary emigration) and capture probabilities of Alasmidonta arcula, Lampsilis dolabraeformis, Lampsilis splendida, and Pyganodon gibbosa in a large lowland river in Georgia. Mussels were sampled in individual habitat units using line-transect methods at ∼6-wk intervals from summer 2006-2007. We used an information-theoretic approach to evaluate the relative importance of maximum river discharge, habitat characteristics, mussel species, and season on temporary emigration (i.e., proportion of mussels not at the surface), apparent survival, and capture probability. The best-supported models indicated that apparent survival and capture probability varied positively with mussel shell length and among habitat types. Apparent survival (6-wk interval) ranged from 94 to 99% and was greatest in slackwater and lowest in swiftwater habitat. Capture probability ranged from 8 to 20% and was greatest in slackwater and lowest in swiftwater habitat. Temporary emigration also varied among species and season and appeared to be related to reproductive behavior, with the largest proportion of mussels occurring at the surface when mussels appeared to be reproductively active. A comparison of catch-per-unit-effort indices to population estimates suggested that the reliability of catch-per-unit-effort indices was influenced by vertical migration behavior and other factors affecting mussel capture probability. © 2011 The North American Benthological Society.

Johnson J.A.,University of Georgia | Wisniewski J.M.,Nongame Conservation Section | Fritts A.K.,University of Georgia | Bringolf R.B.,University of Georgia
Southeastern Naturalist | Year: 2012

Abstract Recovery of imperiled freshwater mussels requires knowledge of suitable host fishes and other early life-history traits. We provide quantitative host information for 6 mussel species from the Altamaha River Basin, GA, 3 of which previously had no host information. Glochidia of Alasmidonta arcula (Altamaha Arcmussel) metamorphosed on 2 species of suckers (Moxostoma spp.); Elliptio hopetonensis (Altamaha Slabshell) on Lepomis macrochirus (Bluegill), Pimephales promelas (Fathead Minnow), and Micropterus salmoides (Largemouth Bass); E. shepardiana (Altamaha Lance) on 2 species of Bullheads (Ameiurus spp.) and L. macrochirus; Lampsilis dolabraeformis (Altamaha Pocketbook) on Bluegill and Largemouth Bass; and L. splendida (Rayed Pink Fatmucket) and Villosa delumbis (Eastern Creekshell) on Largemouth Bass. We also provide descriptions of glochidia morphology for the above mussel species and E. spinosa (Altamaha Spinymussel). Glochidia were correctly identified to species in 88.7% of cases by discriminant function analysis of 3 shell dimensions. Glochidia morphology may be useful for identification of glochidia attached to wild fish, thereby providing additional host information.

Shea C.P.,University of Georgia | Shea C.P.,Tennessee Technological University | Peterson J.T.,University of Georgia | Conroy M.J.,University of Georgia | Wisniewski J.M.,Nongame Conservation Section
Freshwater Biology | Year: 2013

1.North American freshwater mussels have been subjected to multiple stressors in recent decades that have contributed to declines in the status and distribution of many species. However, considerable uncertainty exists regarding the relative influence of these factors on observed population declines. 2.We used an occupancy modelling approach to quantify relationships between mussel species occurrence and various site- and catchment-level factors, including land cover, stream size, the occurrence of drought and reach isolation due to impoundment for 21 mussel species native to the lower Flint River Basin, Georgia, U.S.A. 3.Our modelling approach accounted for potential biases associated with both incomplete detection and misidentification of species, which are frequently not accommodated as sources of bias in freshwater mussel studies. 4.Modelling results suggested that mussel species were, on average, four times less likely to be present following severe drought, but the negative effects of drought declined rapidly with increasing stream size. Similarly, mussel species were 15 times less likely to occupy small streams that were isolated from mainstem tributaries by impoundments. 5.This study provides insight into the effects of natural and anthropogenic factors on freshwater mussel species. Our findings add to a growing body of literature aimed at improving understanding of the predominant factors influencing freshwater mussel populations and fostering the development of more informed and effective conservation strategies. © 2012 Blackwell Publishing Ltd.

Thompson J.S.,Nongame Conservation Section
Journal of the Botanical Research Institute of Texas | Year: 2010

A population of Sarracenia minor var. okefcnokeensis is reported from Kings Bay, a 1390 ha basin swamp 30 km northeast of the Okefenokee Swamp in southeast Georgia. This is the first documented account of the variety in a landform other than the Okefenokee Swamp.

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