Sipsey River Research Articles

Molecular identity crisis: environmental DNA metabarcoding meets traditional taxonomy-assessing biodiversity and freshwater mussel populations (Unionidae) in Alabama.

The use of environmental DNA (eDNA) to assess aquatic biodiversity is a growing field with great potential for monitoring and managing threatened species, like freshwater mussel (Unionidae) populations. Freshwater mussels are globally imperiled and serve essential roles in aquatic systems as a food source and as a natural water filter making their management essential for ecosystem health. Unfortunately, mussel populations are often understudied, and challenges exist to accurately and efficiently describe the full suite of species present. Multispecies eDNA approaches may also be more challenging where freshwater mussel populations are most diverse due to ongoing and significant taxonomic restructuring that has been further complicated by molecular phylogenies using mitochondrial genes. For this study, we developed a microfluidic metabarcoding array that targets a wide range of species, from invertebrates to fishes, with an emphasis on detecting unionid mussels known to be present in the Sipsey River, Alabama. We compared mussel species diversity across six sites with well-studied mussel assemblages using eDNA surveys and traditional quadrat surveys in 2016. We examined how factors such as mussel population density, biomass and location in the river substrate impacted our ability to detect certain species; and investigated unexpected eDNA detections through phylogenetic analysis. Our eDNA results for fish and mussel species were broadly consistent with the data from traditional electrofishing and quadrat-based field surveys, although both community eDNA and conventional sampling detected species unique to that method. Our phylogenetic analysis agreed with other studies that treat Pleurobema decisum and P. chattanoogaense as synonymous species; however, they are still listed as unique species in molecular databases which complicates their identity in a metabarcoding assay. We also found that Fusconaia flava and F. cerina are indistinguishable from one another using a portion of the NADH dehydrogenase Subunit 1 (ND1) marker, which may warrant further investigation into whether or not they are synonymous. Our results show that many factors impacted our ability to detect and correctly identify Unionidae mussel species. Here we describe the obstacles we faced, including the murky phylogeny of Unionidae mussels and turbid river conditions, and our development of a potentially impactful freshwater mussel monitoring eDNA assay.

Thermal sensitivity modulates temporal patterns of ecosystem functioning by freshwater mussels

Abstract The continued global loss of biodiversity highlights the importance of understanding how species loss may impact ecosystem function. Shifting temperatures will accelerate species loss, but will affect species differently. We investigated effects of temperature (10°C, 20°C, or 30°C) on resource acquisition and assimilation (clearance rate, respiration rate, N and P excretion) for 11 freshwater mussel species from a species‐rich assemblage in the Sipsey River, Alabama, U.S.A., to evaluate how temperatures impact co‐occurring species and the ecosystem processes they facilitate. Mussels are assigned to the same guild (i.e., filter‐feeding bivalves), but span a breadth of evolutionary lineages and have a diversity of life history strategies from short‐lived, quickly maturing species to long‐lived, slow‐growing species. Our results indicated that four species (Cyclonaias asperata, Elliptio arca, Lampsilis ornata, and Obovaria unicolor) were thermally sensitive at 30°C, using more energy than they were acquiring. These species spanned three phylogenetic tribes and two different life‐history strategies suggesting thermal tolerance may not necessarily be linked to life history strategy or phylogenetic constraints. When laboratory clearance and excretion rates were scaled to a natural mussel community over a year, we found that relative contributions by the proportion of thermally tolerant and sensitive species to total ecosystem function varied temporally across temperature and flow regimes. Thermal stress enhanced contributions by sensitive species' during summer, as individuals attempted to meet metabolic demands by increasing clearance rates and use of energy stores that increased ammonia excretion. River discharge and background nutrient concentrations also modulated the impact of ecosystem functioning facilitated by mussels. High river discharge in winter and high background nutrient concentrations in the summer decreased the relative contribution of the mussel community. Although mussel species are commonly grouped in a single guild, species‐specific thermal traits modulate their role in the community. As biodiversity decreases, even biomass replacement by surviving mussel species is unlikely to support comparable ecosystem function due to the loss of unique species traits.

Erratum

Erratum

The gut microbiome of freshwater Unionidae mussels is determined by host species and is selectively retained from filtered seston.

Freshwater mussels are a species-rich group of aquatic invertebrates that are among the most endangered groups of fauna worldwide. As filter-feeders that are constantly exposed to new microbial inoculants, mussels represent an ideal system to investigate the effects of species or the environment on gut microbiome composition. In this study, we examined if host species or site exerts a greater influence on microbiome composition. Individuals of four co-occurring freshwater mussel species, Cyclonaias asperata, Fusconaia cerina, Lampsilis ornata, and Obovaria unicolor were collected from six sites along a 50 km stretch of the Sipsey River in Alabama, USA. High throughput 16S rRNA gene sequencing revealed that mussel gut bacterial microbiota were distinct from bacteria on seston suspended in the water column, and that the composition of the gut microbiota was influenced by both host species and site. Despite species and environmental variation, the most frequently detected sequences within the mussel microbiota were identified as members of the Clostridiales. Sequences identified as the nitrogen-fixing taxon Methylocystis sp. were also abundant in all mussel species, and sequences of both bacterial taxa were more abundant in mussels than in water. Site physicochemical conditions explained almost 45% of variation in seston bacterial communities but less than 8% of variation in the mussel bacterial microbiome. Together, these findings suggest selective retention of bacterial taxa by the freshwater mussel host, and that both species and the environment are important in determining mussel gut microbiome composition.

Wetland floodplain flux: temporal and spatial availability of organic matter and dissolved nutrients in an unmodified river

River ecosystem dynamics are strongly regulated by the surrounding watershed. The availability and sources of energy and nutrient resources that drive these systems are controlled by topography, climate, geology, and position in the watershed. Here we examined particulate and dissolved organic matter (POM and DOM, respectively) and nutrient concentrations across an entire watershed during multiple flow regimes in an unregulated, low gradient river with extensive floodplain forests. The objectives of the study were to: (1) determine the influence of watershed position and floodplain connectivity on POM, DOM, and nutrient concentrations; (2) examine the influence of flow variability on POM, DOM, and nutrient concentrations; and (3) develop an empirical rating curve to predict POM, DOM, and nutrient transport and flux. We sampled POM, DOM, and nutrient concentrations (ammonia, nitrate, nitrite and soluble reactive phosphorus) at ten sites across the Sipsey River watershed that varied in their degree of connectivity to the floodplain over a two-year period. Both watershed position and flow regime influenced POM, DOM, and nutrient concentrations. In particular, a large floodplain swamp in the middle of the watershed, the Sipsey Swamp, strongly controlled the relative availability of particulate and dissolved materials in the water. In the headwaters, there was a greater proportion of particulate material in suspension relative to dissolved carbon. While in the downstream reaches, both within and downstream of the Sipsey Swamp, DOC accompanied by greater molecular mass and more aromatic DOM was in greater quantity than particulate materials at high flows. Nutrient concentrations in the stream water tended to decline through the floodplain swamp across all flow conditions and tended to be lower in high flows. We demonstrate that floodplains can disrupt the upstream–downstream continuum by supplying a large quantity of allochthonous organic matter. Using long-term data we estimated the total annual flux of DOC and nitrate to range between 1221–6500 and 24–35 tonnes per year, respectively, between 2007 and 2017 with the highest flux rates occurring during high flow periods. Our study shows the complex dynamics of a natural floodplain river system and generally supports the flood pulse concept by highlighting the importance of wetland complexes and floodplain connectivity on material and nutrient transport. Description of organic matter and nutrient dynamics in natural low gradient rivers is critical to understanding production of organisms, food webs and ecosystem processes in the face of climate and land use changes.

Mercury levels in largemouth bass (Micropterus salmoides) from regulated and unregulated rivers

Within areas of comparable atmospheric mercury deposition rates methylmercury burden in largemouth bass populations vary significantly between regulated and unregulated rivers. To investigate if trophic dynamics strongly influenced pollutant body load, we sampled largemouth bass from two adjacent rivers, one regulated and one unregulated, and applied a suite of biochemical and stable isotope assays to compare their trophic dynamics. Total mercury burden in the bass from the unregulated Sipsey River (Elrod, AL, USA) and the regulated Black Warrior River (Demopolis, AL, USA) averaged 0.87 mg kg−1 and 0.19 mg kg−1 wet weight, respectively. For both populations, age, weight, and length were positively correlated with muscle mercury concentration. Compound specific stable isotope analysis of amino acids showed the trophic position of both populations was just under four. Quantitative and isotopic analysis of neutral lipid fatty acid of Sipsey River bass indicated a greater reliance upon the detrital component of the food web compared to Demopolis Reservoir bass which fed within the autochthonous, pelagic component of the food web. Since the close proximity of the rivers makes differences in atmospheric deposition unlikely and both populations had similar trophic position, our findings indicate that food web dynamics should be included among the factors that can strongly influence mercury concentration in fish.

The Sipsey River, Alabama: A Crayfish Diversity “Hotspot”?

The southeastern United States contains ca. 250 species of crayfish. Of these, 85 are historically known from Alabama. Previous studies have shown that the Sipsey River drainage in western Alabama is a diversity “hotspot” for freshwater mussels (42 spp.) and fishes (102 spp.). This is attributed to diverse geologic features, an intact floodplain, lack of impoundments, and lack of urban centers. Intensive sampling of the Sipsey River drainage over a 2-year period resulted in a collection of 294 crayfish representing 12 species. Three of these species, Cambarus ludovicianus, Orconectes chickasawae, and Procambarus vioscai paynei are of conservation concern. Our results indicate that the Sipsey River harbors a greater richness of crayfish species per area than other drainages surveyed to date in Alabama.

Seasonal and species-specific patterns in abundance of freshwater mussel glochidia in stream drift

Abstract We examined seasonal patterns of abundance of mussel larvae (glochidia) in stream drift in a diverse, large-stream mussel assemblage in the Sipsey River, Alabama, across 1 y. We used recently developed techniques for glochidial identification combined with information about mussel fecundity and benthic assemblages to evaluate how well observed glochidial abundance corresponded to expected abundance based on glochidial production. Glochidia from short-term brooding species (Amblema plicata, Elliptio arca, Fusconaia cerina, Pleurobema decisum, Obliquaria reflexa, and Quadrula asperata) were abundant from May to August but did not occur in drift between November and the end of April. Long-term brooders (Lampsilis spp., Medionidus acutissimus, Obovaria unicolor, and Villosa spp.) occurred in several short peaks in spring, summer, and autumn, but generally were less abundant than short-term brooders. We estimated that the benthic assemblage at our study site produced >500,000 glochidia/m2 annually and...

Diversity, abundance, and size structure of bivalve assemblages in the Sipsey River, Alabama

Abstract Patterns of mussel diversity and assemblage structure in the Sipsey River, Alabama, are described. Qualitative data were used to describe river‐wide patterns of diversity. Quantitative data were used to describe the structure of mussel assemblages at several sites based on whole‐substrate sampling that ensured all size classes were detected. Major human impacts to the stream are limited to apparent effects of coal mining in the headwaters and the impoundment of the lower 9 km of the river by a dam on the Tombigbee River. These impacts resulted in a sharp decline in mussel diversity in the headwaters, and extirpation or decline of populations of several large‐river species in the lower river that were probably dependent on colonization from the Tombigbee River. Despite localized impacts, mussel assemblages throughout much of the river appear to be mostly intact and self‐sustaining. These assemblages have several attributes that differ substantially from those in more degraded streams: (1) high retention of historical species richness; (2) gradual, longitudinal increase in species richness from upstream to downstream, resulting in distinctive headwater and downstream assemblages; (3) ubiquity of most species within particular river segments; (4) low dominance and high evenness with large populations of many species; and (5) frequent recruitment for most species resulting in occurrence of individuals in many size classes. Few detailed and demographically unbiased descriptions of relatively intact mussel assemblages exist. We propose that characteristics described in the Sipsey River can be used as a baseline comparison for assessing relative degree of assemblage alteration in other streams and can serve as goals for restoration efforts. Published in 2010 by John Wiley and Sons, Ltd.

Growth Rates of Chironomids Collected from an Ephemeral Floodplain Wetland

Floodplains are dynamic wetlands that are constant- ly alternating between aquatic and terrestrial phases. To survive these conditions, aquatic invertebrates must have life history strategies allowing them to take advantage of inundation periods. One such strategy is growing rapidly and completing development before flood waters recede. We measured daily growth rates and development times of 7 chironomid species during April, June, and August using egg masses collected from the Sipsey River floodplain, west central Alabama, USA. Egg masses and resulting larvae were reared under ambient temperatures (18-27°C) and with a natural food source. All successfully reared chironomids were in the subfamily Chiro- nominae. Mean growth rate was 0.28 d -1 suggesting a biomass turnover time of 3 days. Mean development time was 17 days. Temperature affected chironomid development time, with slower rates occurring at the lowest temperature. While many chironomid species appear capable of rapid growth in flood- plains when temperatures are >18°C, completion of their life cycle seems likely only if inundation persists at least 2- 3 weeks. Longer inundation periods are probably necessary for chironomids to complete their life cycle at colder temper- atures in winter and early spring.

The Federal Invasion of Pickens County, April 5-7, 1865: Croxton's Sipsey River Campaign

The Federal Invasion of Pickens County, April 5-7, 1865: Croxton's Sipsey River Campaign

Mercury in Southeastern U.S. Riverine Fish Populations Linked to Water Body Type

We compared Hg concentrations in fishes from the regulated Black Warrior River and the unregulated Sipsey River in west Alabama whose neighboring watersheds receive equivalent atmospheric Hg deposition. Average fish fillet Hg concentrations were 3-fold higher in the unregulated river compared to the regulated river. Between river differences in Hg fish concentrations likely originate from structural (e.g., species composition) and functional (e.g., energy flow pathways) differences between the two ecosystems. We tested the generality of these findings by comparing largemouth bass Hg concentrations among unregulated rivers (n=6) and reservoirs (n=11) throughout the southern Coastal Plain geologic region. ANCOVA revealed that at a given bass length, Hg concentrations were approximately 1.75 times higher in unregulated rivers compared to regulated rivers. Aerial deposition of Hg was not correlated to largemouth bass Hg concentrations. We suggest that the link between atmospheric Hg deposition and fish Hg concentrations is significantly modulated by the structure and function of aquatic ecosystems and this accounts for much of the variation in fish Hg concentrations among systems. Unregulated floodplain-rivers in the south have some of the highest fish Hg concentrations on record and should be intensely monitored to establish human consumption risks.

Using morphometrics to identify glochidia from a diverse freshwater mussel community

We measured shell length, hinge length, and height of glochidia from 21 freshwater mussel species occurring in the Sipsey River, Alabama, to test our ability to identify species based on these glochidial morphometrics. Glochidial size and shape differed widely among species; for all 3 dimensions, mean values for the largest species were 5 to 73 greater than for the smallest species. Within-species variation in glochidia size was low for all species with the exception of Pleurobema decisum, which was represented by 2 glochidial morphotypes; variation within each morphotype was similar in magnitude to variation within other species. We were able to classify 72 to 79% of total glochidia (n 5 870 or 750, respectively) to the correct species with discriminant function analysis. Percentage of correct classification ranged from 40 to 100% for individual species. Misclassifications were caused by overlap in shell dimensions between some species, but even species with poor clas- sification success were confounded with an average of only 2.2 to 3.0 other species. Unlike previous studies, we found that glochidia of closely related species were not necessarily more similar to each other than to glochidia of more distantly related species. For example, species in the tribe Quadrulini were widely divergent in glochidium size and represented some of both the smallest and largest glochidia in our study. These 3 shell measurements and subsequent application of discriminant func- tion analysis can be useful for identification of unknown glochidia or for rapidly narrowing the range of potential species identifications to smaller groups of species with similar glochidia.

Invertebrate responses to decreasing water levels in a subtropical river floodplain wetland

Unregulated river floodplains are dynamic environments, and invertebrates living in these wetlands must be able to respond to fluctuating water levels. As water levels decrease in the floodplain, aquatic and semi-aquatic invertebrates may either move with the receding water or remain and become exposed to drying on non-inundated floodplain soil. Invertebrates inhabiting floodplains may use several strategies to cope with exposed (non-inundated) conditions; they may survive exposure by forming desiccation-resistant stages, emerging as adults (insects only), or living in a non-dormant state in exposed soil. To investigate invertebrate responses to a receding water line, benthic core samples were collected in exposed and inundated floodplain soil at successively lower water levels after a flood in the Sipsey River floodplain, west central Alabama. Insect emergence was also compared on inundated and exposed floodplain. Some invertebrate groups moved with the receding water line (aquatic chironomids, ostracods, cladocerans, copepods, Acari, and stratiomyids), while others did not (semi-aquatic/terrestrial chironomids, collembolans, oligochaetes, nematodes, diplurans, proturans, tenebrionids, and sciarids). Chironomids were the dominant emerging insect (73%), and adults emerged from both inundated (33 individuals m−2 d−1) and exposed floodplain soil (15 individuals m−2 d−1). These results document the importance of at least two survival strategies for aquatic invertebrates: moving with decreasing water levels and emerging from exposed floodplain soil (insects only). The semi-aquatic taxa not responding to receding water can survive in both exposed and inundated soil, at least for the short period observed in this study. Thus, many floodplain invertebrates in small-to-medium sized rivers are able to cope with a dynamic and unpredictable inundation pattern, which likely enhances wetland productivity.

Rediscovery, Distribution and Phytogeographic Affinities of Leptogramma pilosa in Alabama

*Department of Botany and Microbiology, School of Agriculture and Agricultural Experiment Station, Auburn University, Auburn, AL 36830. 'The nomenclature of river at collecting site is confused. On recent highway and topographic maps, it is called Sipsey Fork. Colloquially it is called Sipsey River or just the Sipsey. The full and correct name perhaps should be Sipsey Fork of Black Warrior River. Volume 67, number 4, of JOURNAL was issued December 31, 1977. 1

New Records for Anzia ornata from Alabama

Collections of Anzia ornata (Zahlbr.) Asah. are reported from Winston, Shelby, and Tallapoosa Counties, Alabama. For many years Anzia colpodes (Ach.) Stizenb. was the only member of that genus known from North America. In 1961 Culberson announced the collection of a second Anzia, A. oranta (Zahlbr.) Asah., on this continent. This species is readily distinguished from A. colpodes by the presence of granular marginal soredia easily visible with a hand lens. Culberson's collection was from Duplin County, North Carolina. During 1962 and 1968, three additional records of the occurrence of Anzia ornata have been made in Alabama: 1. On March 17, 1962, and again on February 20, 1968, the author with Dr. Aino Henssen collected A. ornata in Winston County in the Cumberland Plateau Region of Alabama (Johnston 1930). Specimens were taken from the bark of Oxydendron arboream and Quercus montana in a 1 Dept. of Biology, Howard College, Birmingham 9, Alabama. This content downloaded from 207.46.13.128 on Tue, 06 Sep 2016 05:48:28 UTC All use subject to http://about.jstor.org/terms 1963] MCCULLOUGH: ANZIA ORNATA 237 ravine, two miles west of the Sipsey River Picnic Area in the Bankhead National Forest (McCullough 583, 1202, 1213). 2. On February 21, 1963, Dr. Aino Henssen with the author collected A. ornata in Shelby County in the Valley and Ridge Province of Alabama (Johnston 1930). The specimen was taken from bark of oak at Falling Rock, a waterfall and ravine area about five miles north of Montevallo (Henssen 15152a). 3. On December 28, 1962 the author collected A. ornata in Tallapoosa County in the piedmont upland of Alabama (Johnston 1930). The specimen was taken from the bark of Carya sp. along Elkahatchee Creek about four miles south of Alexander City (McCullough 1066). While the species was not abundant in any of the three areas, adequate specimens could easily be obtained.

A New Fern for the United States

On October 15, 1949, Dr. A. M. Harvill and the writer made a trip into Winston County, Alabama. We stopped to examine some rock shelters formed in Pottsyille sandstone along the southern edge of the West Fork of the Sipsey River about five miles east of Double Springs. Growing in fissures and along the ground we found a number of ferns such as Trichomanes Boschiawnum Sturm, Asplenium pinnatifidum Nutt., Athyriuum asplenioides (Michx.) Eaton, Thelypteris normalis (C. Chr.) Moxley, Polystichum acrostichoides (Michx.) Schott, Osmunda regalis L., 0. cinnamomea L., and a specimen which was sent to Dr. Wherry for identification. Dr. Wherry turned the identification over to Mr. George Proctor; who identified the specimen tentatively from Christensen's monograph of Dryopteris as Dryopteris pilosa (Mart. et Gal.) C. Chr. He took a few sprigs to the National Herbarium, where he and C. V. Morton compared it with Mexican material. They found it to match almost exactly a specimen of D. pilosa (determined by Maxon), collected near Mesa Correo, Chihuahua, Mexico, LeSieur 1144 (USNH 1,638,030). Mr. Morton and Dr. Wherry suggested the possibility of a new varietal status and Dr. Wherry suggested a new combination under Thelypteris. A loan of specimens was requested from the National Herbarium and the Academy of Natural Sciences of Philadelphia, designated in this paper by US and PH respectively, for my study of this fern. Examining 41 specimens of Mexican and Guatemalan material, the writer found very little variation in specimens of D. pilosa and D. pilosa var. procurrens (Fee) C. Chr. except in size. LeSueur 1144, mentioned previously, and Gentry 2112, collected at Saguaribo on 15