Obermeyer Et Al
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Range Reductions of Southeast Kansas Unionids Brian K. Obermeyeri, David R. Edds^ Edwin J. Milleri, and Carl W. Prophet^ ^Emporia State University, Division of Biological Sciences, Emporia, Kansas ^Kansas Department of Wildlife and Parks, Independence, Kansas Abstract. Between 1993 and 1995, we studied freshwater mussel assemblages at 75 sites in the Neosho and Verdigris basins of southeast Kansas, and caught 12,826 mussels of 32 species. We targeted four species of special concern (formerly C2 federal candidates): Neosho mucket, Lampsilis rafinesqueana; western fanshell, Cyprogenia aberti; Ouachita kidneyshell, Ptychobranchus occidentalis; and rabbitsfoot, Quadriila cylindrica. Comparison of present distributions with historical records dating to 1885 suggests substantial range reductions for several unionid species, including these four candidates as well as the inferred extirpation of the black sandshell, Ligumia recta. Disparity between the number of extant species and species represented only by weathered valves revealed a decrease in species richness in all but one stream. Little evidence of recruitment was noted. We believe the most widespread contributor to mussel declines in southeast Kansas has been the cumulative effect of stream deterioration from nutrient and sediment loading, which has especially degraded deeper habitats that once likely served as important juvenile nursery areas and refugia from drought. Other factors, such as dams, channel alterations, overharvesting, and stochastic events, have also likely contributed to this decline. Introduction Kansas is located on the western edge of North ever, mussels often leave behind weathered valves, America's rich diversity of freshwater mussels. The especially in Kansas' limestone-buffered waters, state's highest concentration of unionids is generally with which one can compare the presence of extant confined to streams in its eastern third; only 8 of the species (i.e., live and recently dead specimens). 44 species of mussels for which there are historic Using historical records to supplement dead records in Kansas occur in the western two-thirds of shell material, we assessed unionid faunal change in the state (Murray and Leonard 1962). The southeast the Neosho and Verdigris River basins of southeast ern third of the state, especially the Verdigris and Kansas. By comparing shell evidence of past mussel Neosho River basins, contains the highest diversity populations to this study's collection of live of unionids, 37 species. Important mussel streams unionids, we found that range reductions had within these two basins include the Fall, Elk, Verdi occurred in Kansas. gris, and Caney rivers (Verdigris basin) and the Neosho, Cottonwood, and Spring rivers (Neosho basin). Presently there are 6 unionid species state- listed as endangered, 4 as threatened, and 12 as Study Area species in need of conservation (SING); 5 of these above are species of concern (formerly C2 federal The Neosho and Verdigris River basins are located in the tallgrass prairie ecoregion, formerly an candidates). In addition, four species are considered extensive grassland dominated by warm-season extirpated from the state: Alasmidonta viridis, grasses with riparian forests bordering most Epioblasma triquetra, Ligumia recta, and Obovaria streams. Today remnants of this upland prairie olivaria. remain in the western half of the study area, espe Assessing change in Kansas unionid assem blages occurring in the past century is challenging cially in the headwaters of the Neosho and much of because most surveyors (e.g., Popenoe 1885; Call the Verdigris River basins; however, many of these 1885a, 1885b, 1885c, 1885d, 1886,1887; Scammon grasslands are degraded because of intensive grazing, and little remains of bottomland prairies 1906) did not provide relative or rank abundances of due to extensive cultivation. Upland heavy-clay species and often gave ambiguous locality descrip tions. Prior to more recent work (e.g.. Cope 1983, soils are generally shallow with limestone and chert 1985; Miller 1993; Obermeyer et al. 1995), only Isely outcroppings of Permian and Pennsylvanian origins (1924) provided relative abundances; however, he preventing cultivation in many areas, whereas alluvial soils predominate in the floodplain. Spring sampled only two sites in Kansas (in 1912). How River and Shoal Creek differ in that they are derived Obermeyer et al.: Range Reductions of Southeast Kansas Unionids 109 from the Ozark Plateau and are characterized by cm diameter PVC pipe frame), and sieved the lower turbidity and richer aquatic faunas (Cross and substrate. The number of sieve samples varied Collins 1995). between 0 and 21, depending on size and quality of Streams in the Neosho and Verdigris River the site and time or weather constraints. We also basins have been affected by anthropogenic activi quantitatively sampled 16 sites from four streams ties. For example, the Neosho River has lost much (Neosho, Spring, Verdigris, and Fall rivers) using a of its watershed grasslands except in headwater 1-m quadrat placed along measured coordinates reaches and has been polluted by effluents from oil chosen randomly, for a total of 505 1-m quadrats. In fields, feedlots, and cropland, which contrasts with each quadrat we excavated substrate to a depth of Isely's (1924) description of this river in 1912 as "a 10-15 cm and identified and recorded the size of all splendid clear water stream." It has been further unionids found within or under the quadrat frame. modified by 15 city dams, numerous flood-control In addition to collecting live mussels, we impoundments, and two federal reservoirs. Council searched exposed gravel bars and banks of streams Grove Lake and John Redmond Reservoir. Not only for dead shell material. We noted the presence of have unionids been affected in the Neosho River each species and divided the dead shells into two with the inferred loss of three species, but these categories: fresh and weathered. A shell classified as changes are also linked to a deterioration of its fish fresh had a bright, unfaded nacre and much of its fauna, with the presumed extirpation of the bigeye periostracum, with the exception of normal umbonal chub (Notropis amblops), spotfin shiner {Cyprinella erosion. Weathered shells ranged from exhibiting spiloptera), northern hogsucker {Hypentelium considerable erosion of the periostracum and a nigricans), banded sculpin (Cottus carolinae), Ameri faded, often chalky nacre, to being highly weathered can eel {Anguilla rostrata), and chestnut lamprey without any remains of the periostracum; these {Ichthyomyzon castaneus) (Cross 1967; Cross and varied from whole valves to identifiable fragments. Braasch 1968; F.B. Cross, University of Kansas, pers. We estimated the abundance of dead shell material comm.). of each species as either rare (1-2 valves), few (3-6 valves), common (7-16 valves), or abundant (>16 valves). In each of six streams (Neosho, Cottonwood, Methods Spring, Verdigris, Fall, and Elk rivers), we tallied the number of extant species (live plus fresh dead shells) We surveyed 75 sites in 13 streams in the Neosho versus the number of species represented only by and Verdigris basins of southeast Kansas during the weathered shells, and used a paired t-test to assess summers of 1993-1995 to assess the current distribu significant differences. tion of the four targeted species: Lampsilis Voucher specimens and nomenclature: We rafinesqueana (Neosho mucket), Ptychobranchus assembled a representative collection of dead occidentalis (Ouachita kidneyshell), Cyprogenia aberti specimens and deposited them at the Ohio State (western fanshell), and Quadrula cylindrica University Museum of Zoology in Columbus, Ohio. (rabbitsfoot). Site selection was based on past We have also assembled a more extensive collection occurrence of the four targeted species, or sites with for future deposition at the Kansas Biological habitats described as suitable for them (e.g., Murray Survey, Lawrence, Kansas. Except for a few speci and Leonard 1962; Oesch 1984; Cope 1979,1983, mens collected for reference, live unionids were 1985; Mather 1990). Sites with quantified searches identified in the field and returned to their original were located on the Caney, Cottonwood, South Fork location. Unionid nomenclature follows Williams et of the Cottonwood, Neosho, Verdigris, Spring, Fall, al. (1993); however, subspecies are not recognized in and Elk rivers, and Cow, Doyle, Labette, Otter, and this paper. Shoal creeks (Figure 1). However, for our historical analysis, we concentrated on 64 sites in the Neosho, Cottonwood, Spring, Verdigris, Fall, and Elk rivers. We conducted snorkel searches in shallow Results water (15 cm to <1 m), and SCUBA was used when depth exceeded 1 m. All searches were timed to We caught 12,826 live mussels of 32 species from the quantify sampling effort. Sampling effort at each six streams targeted for historical analysis (Table 1). site ranged from 40 minutes to 9 hours. To seek Recruitment was noticeably lacking from most sites, evidence of recruitment, we dredged substrate with with only four sites revealing recent recruits (<5 a shovel, transferred it to a floating sieve (6 mm years old) of "candidate" species: Neosho River (1), galvanized mesh screen supported by a l-m^ x 15- Spring River (1), and Verdigris River (2). 110 Conservation and Management of Freshwater Mussels II: Proceedings of a UMRCC Symposium Figure 1. Map of streams targeted for unionid range reduction in southeast Kansas. In the Neosho River,