Toledo Bend Relicensing Project: Lower Sabine River Mussel Study

Transcription

1 Final Draft Report Presented to the Sabine River Authority Toledo Bend Relicensing Project: Lower Sabine River Mussel Study Investigators Charles R. Randklev 1, Benjamin J. Lundeen 2, Joseph Skorupski 1, James H. Kennedy 1 and Steve Wolverton 3 Submitted March Department of Biology, University of North Texas, PO Box , Denton, TX Minnesota Pollution Control Agency, 7678 College Road, Suite 105, Baxter MN Department of Geography, University of North Texas, PO Box , Denton, TX

2 Table of Contents: Introduction...3 Study area...3 Methods...6 Results/Discussion...6 Abundance and distribution...6 Physical data...8 Population structure for selected sites...8 Noteworthy finds...15 References cited...18 Photograph of live Lampsilis satura (Sandbank Pocketbook) collected from Reach 4 in the lower Sabine River. 2

3 Introduction Unionids have decreased in number and distribution throughout the United States. Of the 297 species known to occur historically in North America, 12% are thought to be extinct, and 23% are considered to be threatened or endangered (references in Galbraith et al. 2008). At least 52 species have been reported in Texas (Howells et al. 1996), 15 of which are listed as threatened by the state. Several characteristics of freshwater mussels render them susceptible to range reductions and extirpations (Vaughn and Taylor 1999). Unionids are long-living, sedentary organisms that spend a portion of their lives as ectoparasites on fish (Vaughn and Taylor 1999; Galbraith et al. 2008). As a result, anthropogenic impacts such as overharvesting, urban sprawl, stream impoundments, poor agriculture practices, introduction of alien species, and apathetic land-management policies have reduced or eliminated many unionid populations (Neck 1982; Bogan 1993; Strayer 1999; Vaughn and Taylor 1999; Watters 2000; Lydeard et al. 2004). The extent of unionid decline in many river drainages is either unknown or only now becoming apparent (Lydeard et al. 2004; Bogan 2008). This lack of knowledge regarding current mussel population distributions is a major impediment to mussel conservation (The National Native Mussel Conservation Committee 1998). This is true for the lower Sabine River, where only one formal study on unionids has been conducted (Randklev et al. 2009a). In this study, 12 unionid species were identified, two of which are listed as threatened by the state. The scope of the Randklev et al. (2009a) study, however, was aimed at understanding the relationship between substrate and hydrology and not at evaluating the overall distribution of unionids in the lower Sabine River. In this study, we assess the distribution and abundance of unionids in the lower Sabine River between Toledo Bend Dam and U.S. Highway 190. This study was done in support of SRA relicensing efforts for the Toledo Bend Project to provide information on existing aquatic resources and assist in identifying potential project effects and Protection, Mitigation, and Enhancement (PME) measures, if appropriate. Study Area The Sabine River rises near Greenville, Texas, east of Dallas and flows southeast where it becomes the state line near Logansport, Louisiana. From Logansport, the Sabine River turns south and joins the Neches River in Sabine Lake, it then flows through Sabine Pass and empties into the Gulf of Mexico (Huser 2000). The Sabine River is impounded by three major dams, two on the main river (Lake Tawakoni and Toledo Bend Reservoir) and one (Lake Fork Reservoir) on Lake Fork Creek, a major tributary (Huser 2000). Toledo Bend Reservoir is the largest and lowermost impoundment on the Sabine River, with a surface area of 735 km 2 and a capacity of 5.5 x 10 9 m 3 at normal water levels (Phillips 2008). Completed in 1967, the primary purpose of Toledo Bend Reservoir is hydropower generation (Phillips 2008). Because of this, flow in this portion of the Sabine River is highly pulsed during periods of power generation (Phillips 2008). Collection sites are located between Toledo Bend Reservoir [RM 147] and U.S. Highway 190 [RM 90] (Figure 1 and Table 1). The study area was delineated into four reaches, with a minimum of three collection sites per reach. Both the study area and the length of each reach were delineated by the Sabine River Authority. 3

4 FIGURE 1. Collection sites in the lower Sabine River. 4

5 TABLE 1. GPS coordinates, sample reach, approximate river mile and date sampled for each mussel collection site. Sites are listed in sequence from upstream to downstream. Site Reach River Mile Coordinates Date sampled 18 1 Near R /10/ Near R /22/ Near R /22/ Near R /23/ Near R /10/ Near R /10/ Tailrace 15R /21/ Near R /21/ Near R /26/ Near R /26/ Near R /11/ Near R /26/ Near R /11/ Near R /11/ Near R /9/ Near R /9/ Near R /7/ Near R /7/ Near R /8/ Near R /8/ Near R /23/ Near R /24/ Near R /24/ Near R /6/ Near R /25/ Near R /25/ Near R /25/2010 5

6 Methods Because limited information exists regarding the distribution and abundance of unionids in the lower Sabine (RM 147 RM 90), a site reconnaissance survey was performed. During the reconnaissance survey, the entire length of the Sabine River between Toledo Bend Reservoir and U.S. Highway 190 was traversed by motorized boat. Reconnaissance searches were conducted where shells and/or living mussels were observed. Based on the results from this survey, a minimum of three sites per reach were selected; criteria for site selection were based on the number of living individuals collected and/or the species richness observed (live and spent valves) at each site. The selected sites were revisited between April 21-26, 2010, and October 6-11, 2010, during low flow conditions. At each site, a three hour timed search was conducted. Mussels were located both visually and tactilely. SCUBA and snorkeling methods were used in areas deeper than 1 m or where water clarity was poor. Mussels were brought to shore, identified and then returned to the water alive after sampling was completed. Mussel length was recorded with calipers to the nearest 0.1 mm (this included individuals categorized as veryrecently dead; i.e., individuals with tissue present within the shell). Water velocity (m/s), depth (m) and dominant substrates were recorded at sites where mussels were found. When possible, water temperature ( o C), dissolved oxygen (DO, mg/l and % saturation), ph and specific conductivity (µs/cm) were recorded for each site with a Hydrolab 4a. A global positioning system receiver, Garmin etrex, was used to record locations; WGS84 was used for the Datum and UTM as the coordinate system. Results are presented by site as species richness (number of species observed), total abundance (total number of individuals collected) and catch-per-unit effort (number of mussels/person-hour). Shell length histograms are provided for sites that had sufficient numbers of living individuals to assess recruitment. Results/Discussion Abundance and distribution: In total, 309 live mussels, representing 15 species, were documented at the sample sites, including two species listed as threatened by the state: Fusconaia askewi (Marsh, 1896) [Texas Pigtoe] and Lampsilis satura (I. Lea, 1852) [Sandbank Pocketbook] (Table 2). The highest catch rate, largest abundance per site and greatest species richness occurred in the lower part of Reach 3 and Reach 4 (Table 3). In contrast, live mussels were absent from Reach 1 and in low abundance in Reach 2 and the upper part of Reach 3. However, in Reach 1, during the reconnaissance survey, the following species were live when collected: Utterbackia imbecillis (Say, 1829), Lampsilis hydiana (I. Lea, 1838), Lampsilis teres (Rafinesque, 1820), Leptodea fragilis (Rafinesque, 1820) and Pyganodon grandis (Say, 1829). In Reach 2, live mussels were only collected from one site, which was located in a oxbow disconnected from the river channel (Scoggins Bend). Lampsilis teres, P. grandis and U. imbecillis were also present at this site (Table 3). 6

7 TABLE 2. Summary of unionids collected between April 21-26, 2010, and October 6-11, 2010, from the lower Sabine River basin below Toledo Bend Reservoir. Site identification numbers (and river miles) include: Site 19 (134.3), Site 14 (121.2), Site 16 (119.0), Site 15 (113.9), Site 7 (108), Site 8 (107.5), Site 9 (104.3), Site 13 (103.8), Site 11(103), Site 10 (100) and Site 12 (96.5). Common name Live + RD (n) Recently dead (RD) Reach Sites Amblema plicata Threeridge 5-3,4 9,13 Anodonta suborbiculata Flat floater Fusconaia askewi Texas Pigtoe ,12,13 Lampsilis hydiana Louisiana Fatmucket ,4 7,8,9,10,11,13,14,15,16 Lampsilis satura Sandbank Pocketbook ,12,13 Lampsilis teres Yellow Sandshell 51-2,3,4 7,8,9,10,13,15,19 Leptodea fragilis Fragile Papershell ,4 7,10,13,14,15,16 Potamilus purpuratus Bleufer Pyganodon grandis Giant Floater 36-2,3 9,19 Quadrula apiculata Southern Mapleleaf ,12,13 Quadrula mortoni Western Pimpleback ,4 7,10,11,12,13,14 Quadrula nobilis Gulf Mapleleaf ,11,12,13 Quadrula verrucosa Pistolgrip Utterbackia imbecillis Paper Pondshell Villosa lienosa Little Spectaclecase 8 1 3,4 7,10,12,15 Unknown Total Most of the mussels collected were found in habitats with consolidated substrate, which occurred in portions of the river that had woody debris and/or in habitats that minimized bed movement and scouring. These habitats were found behind point sandbars, littoral areas, side channels and in protected backwater areas (Figure 2). Mussel species richness and abundance increased with distance downstream (Table 3, Figure 3). Lampsilis hydiana, L. teres, P. grandis and U. imbecillis were the dominant species in Reaches 1, 2 and 3. In contrast, Quadrula mortoni (Conrad, 1835) was the most abundant species collected in Reach 4. Additionally, five species, including two species that are threatened in Texas, were only collected in Reach 4: Fusconaia askewi (Marsh, 1896), Lampsilis satura (I. Lea, 1852), Potamilus purpuratus (Lamarck, 1819), Quadrula apiculata (Say, 1829) and Quadrula nobilis (Conrad, 1854). Long dead and subfossil shell material of these species was collected in the upper portion of the study area, suggesting that these species occurred historically in this portion of the Sabine River (Randklev et al. 2009b); however, it should be noted that these shells could also represent preproject conditions or that they were flushed downstream from the reservoir. 7

8 FIGURE 2. Pictures of habitats where living mussels were collected: A) point sandbars, B) littoral areas, C) woody debris and D) backwater areas/pools. Physical data: An upstream to downstream thermal gradient was observed during both survey periods. Water temperature was measured for a minimum of one hour at each collection site; water temperature increased with distance downstream. For the April sampling period, mean water temperature in Reach 1 was 15 C; mean water temperature did not become warmer until Reaches 3 and 4, with 23.5 C and 24.6 C recorded, respectively. For the October 6-11 sampling period, mean water temperature in Reach 1 was 19.1 C, whereas mean water temperature for Reach 3 was 22.4 C. Compared to the April sampling period, water temperature was approximately 4 C warmer near the impoundment during the October sampling. Impoundment release during the April sampling period may have caused this difference; mean discharge (USGS gauging station ) in Reach 1 ranged from 11.1 cms (4/22/2010) to 33.7 cms (4/23/2010) during sampling in April, whereas mean river discharge from the tailrace was 8.4 cms (10/10/2010) in October. Population structure for selected sites: Size frequency histograms using 5-mm class intervals are presented by site for species with 5 specimens measured (Figures 4-7). Median, minimum and maximum shell length (mm) for mussel species collected in the lower Sabine River are summarized in Table 4. 8

9 TABLE 3. Summary of unionids collected per site between April 21-26, 2010, and October 6-11, 2010, from the lower Sabine River basin below Toledo Bend Reservoir. Numbers in parenthesis denote recently dead (soft tissue present within the shell) individuals, which are included in the total number reported. Reach 2 Reach 3 Reach 4 Species Site 19 RM Site 14 RM Site 16 RM 119 Site 15 RM Site 7 RM 108 Site 8 RM Site 9 RM Site 13 RM Site 11 RM 103 Site 10 RM 100 Amblema plicata 4 1 Anodonta suborbiculata 5 Fusconaia askewi Lampsilis hydiana (1) Lampsilis satura 2 8 (2) 1 Lampsilis teres Leptodea fragilis 1 (1) Potamilus purpuratus 1 (1) Pyganodon grandis 1 35 Quadrula apiculata Quadrula mortoni (1) Quadrula nobilis Quadrula verrucosa 1 Utterbackia imbecillis 14 Villosa lienosa (1) Unknown 1 Total (n) Species richness Catch-per-unit effort (number/hour) Site 12 RM

10 FIGURE 3. Species richness (A) and catch-per-unit effort (B) for collection sites on the lower Sabine. Sites are listed in longitudinal sequence from upstream to downstream. These graphs indicate that mussel species richness and abundance increase with distance downstream. 10

11 FIGURE 4. Size frequency distribution (length) of: A) Utterbackia imbecillis, Site 19; B) Quadrula mortoni, Site 12; C) Lampsilis hydiana, Site 13 and D) Quadrula mortoni, Site

12 FIGURE 5. Size frequency distribution (length) of: A) Lampsilis hydiana, Site 15; B) Lampsilis teres, Site 15; C) Lampsilis hydiana, Site 7 and D) Leptodea fragilis, Site 7. 12

13 FIGURE 6. Size frequency distribution (length) of: A) Anodonta suborbiculata, Site 9; B) Lampsilis teres, Site 9; C) Pyganodon grandis, Site 9 and D) Lampsilis hydiana, Site 10 (D). 13

14 FIGURE 7. Size frequency distribution (length) of: A) Lampsilis satura, Site 10; B) Quadrula mortoni, Site 10; C) Lampsilis teres, Site 13 and D) Quadrula nobilis, Site

15 TABLE 4. Median, minimum and maximum shell length (mm) for mussel species collected in the lower Sabine River. Minimum and maximum values were not reported if only a single individual for a given species was collected (these are denoted by dashed lines). Species Reach Median Minimum Maximum Maximum shell length (mm) (mm) (mm) (mm) (Howells 2010) Lampsilis teres Pyganodon grandis Utterbackia imbecillis Amblema plicata Anodonta suborbiculata Lampsilis hydiana Lampsilis teres Leptodea fragilis Pyganodon grandis Quadrula mortoni Villosa lienosa Amblema plicata Fusconaia askewi Lampsilis hydiana Lampsilis satura Lampsilis teres Leptodea fragilis Potamilus purpuratus Quadrula apiculata Quadrula mortoni Quadrula nobilis Quadrula verrucosa Villosa lienosa Noteworthy finds: Historically, L. satura ranged north and east of the San Jacinto River (Howells et al 1997; Howells 2009) (Figure 8). Currently, this species has been reported from the Angelina River, the upper and lower Neches River, Village Creek and the upper and lower Sabine River. Lampsilis satura is a lotic species that occurs in gravel, mud and sandy bottom streams and rivers with slow to moderate flows (Howells et al. 1996). Lampsilis satura does occur in the lower Sabine downstream of U.S. Highway 190 but in low numbers (Randklev et al. 2009a). During the reconnaissance survey, two live individuals were collected in Reach 4 (Randklev et al. 2009b). In the April survey, L. satura was collected again in Reach 4 at Sites 10 and 12 but was most abundant at Site 10 (Table 3). At both sites live individuals were observed partially buried in the gravel/sand substrate. Five males and three gravid females were collected at Site 10; two of the females had recently died, having been apparently stranded as water levels receded. During the October survey, two males exceeding 119 mm in shell length were collected at Site

16 FIGURE 8. Map of L. satura s range (adapted from Randklev et al. 2010). Presumptive historical range (shaded gray) follows the findings of Howells (2009). Extant populations of L. satura are shaded orange. Fusconaia askewi historically occurred throughout the Neches-Angelina, San Jacinto, Sabine, and Trinity River drainages (Howells et al. 1996, 1997; Howells 2009) (Figure 9). Extant populations are known to occur in the upper and lower Sabine, Angelina River, upper Neches River, Village Creek and West Fork of the San Jacinto River. The upper Sabine is the only location where this species has been found in large numbers. Fusconaia askewi inhabits moderate-sized streams with flowing waters and is not known to tolerate impoundment or lentic conditions (R.G. Howells pers. comm. 2010). In the lower Sabine, F. askewi is found in areas protected by woody debris; this type of habitat is thought to provide protection during high river discharges (Randklev et al. 2009a). Fusconaia askewi was not found during the reconnaissance survey. However, shell material for this species was collected throughout the study area suggesting that it was widely distributed and perhaps abundant in this basin (Randklev et al. 2009b). During the April survey, F. askewi was collected at Sites 10 and 12 in Reach 4 but in low numbers (Table 3); substrate at both sites consisted of a sand/gravel mixture. During the October sampling, two live individuals were collected at Site 13 in Reach 4. Results from both sampling events suggest that this species is rare in the lower Sabine River. 16

17 FIGURE 9. Map of F. askewi s range (adapted from Randklev et al. 2010). Presumptive historical range (shaded gray) follows the findings of Howells (2009). Extant populations of F. askewi are shaded orange. Anodonta suborbiculata is not endemic to Texas, but it now ranges as far west as the Brazos River drainage. This species occurs in the upper Sabine River drainage (Howells 1997). Anodonta suborbiculata inhabits flood-plain streams, lakes and swamps in deep mud and silt and appears tolerant of impoundments (Howells et al. 1996; Randklev and Lundeen unpublished data). This species was not previously reported in the lower Sabine (Strecker 1931; Vidrine 1993; Howells 2001, 2005; Karatayev and Burlakova 2007, 2008; Randklev et al. 2009a,b). In April, this species was collected at Site 9 in Reach 3. Site 9 is an isolated series of protected backwater pools located near the confluence of Anacoco Bayou and the Sabine River. At least one of the pools is spring fed, and probably maintains flow during extended periods of low flow. Substrate in these pools consisted of an unconsolidated mixture of sand and mud. Small and large individuals were collected from this site but were greater than 30 mm in shell length. 17

18 References cited Bogan, A.E Freshwater bivalve extinctions (Mollusca: Unionoida): a search for causes. American Zoology 33: Bogan, A.E Global diversity of freshwater mussels (Mollusca, Bivalvia) in freshwater. Hydrobiologia 595: Galbraith, H.S., D.E. Spooner, and C.C. Vaughn Status of rare and endangered freshwater mussels in southeastern Oklahoma rivers. Southwestern Naturalist 53: Howells, R.G Distributional surveys of freshwater bivalves in Texas: Progress report for Texas Parks and Wildlife Department, Management Data Series 187, Austin. Howells, R.G., R.W. Neck, and H.D. Murray Freshwater mussels of Texas. Texas Parks and Wildlife Department, Austin, Texas. 224 pp. Howells, R.G Status of freshwater mussels (Bivalvia: Unionidae) of the Big Thicket region of eastern Texas. Texas Journal of Science 49: Howells, R.G., C.M. Mather, and J.A.M. Bergmann Conservation status of selected freshwater mussels in Texas. Pages , In K.S. Cummings, A.C. Buchanan, C.A. Mayer, and T.J. Naimo (Eds.). Conservation and management of freshwater mussels II: Initiatives for the Future. Proceedings of a Upper Mississippi River Conservation Committee symposium, Rock Island, Illinois. Howells, R.G Distributional surveys of freshwater bivalves in Texas: Progress report for Texas Parks and Wildlife Department, Management Data Series 233, Austin. Howells, R.G Biological opinion: conservation status of selected freshwater mussels in Texas. 24 pp. Manuscript on file with authors. Huser, V Rivers of Texas. Texas A & M University Press, College Station, Texas, USA. Karatayev, A.Y., and L.E. Burlakova East Texas Mussel Survey. State Wildlife Grant submitted to Texas Parks and Wildlife Department, Austin. Karatayev, A.Y., and L.E. Burlakova Distributional Survey and Habitat Utilization of Freshwater Mussels. Interagency final report submitted to the Texas Water Development Board March Lydeard, C., R.H. Cowie, W.F. Ponder, A.E. Bogan, P. Bouchet, S.A. Clark, K.S. Cummings, T.J. Frest, O. Gargominy, D. Herbert, R. Hershler, K.E. Perez, B. Roth, M. Seddon, E.E. Strong, and F.G. Thompson The global decline of nonmarine mollusks. Bioscience 54:

19 National Native Mussel Conservation Committee National strategy for the conservation of native freshwater mussels. Journal of Shellfish Research 17: Neck, R.W A review of interactions between humans and freshwater mussels in Texas. Pages ,In J.R. Davis (Eds.). Proceedings of the Symposium on Recent Benthological Investigations in Texas and Adjacent States. Austin: Texas Academy of Science. Phillips, J.D Geomorphic units of the lower Sabine River. Interagency final report submitted to the Texas Water Development Board August Randklev, C.R., J.H. Kennedy, and B.J. Lundeen. 2009a. Distributional survey and habitat utilization of freshwater mussels (Family Unionidae) in the lower Brazos and Sabine River basins. Interagency final report submitted to the Texas Water Development Board August Randklev, C.R., B.J. Lundeen, J.H. Kennedy, and S. Wolverton. 2009b. Report on the Reconnaissance Survey of the Lower Sabine River, September Interagency report submitted to the Sabine River Authority November Randklev, C.R., B.J. Lundeen, and J.H. Kennedy Summary of unpublished records for candidate mussel species from four museums in north central Texas. Report submitted to the Greater Edwards Aquifer Alliance. Strayer, D.L Effects of alien species on freshwater mollusks in North America. Journal of the North American Benthological Society 18: Strecker, J.K The distribution of the naiads or pearly fresh-water mussels of Texas. Baylor University Museum Special Bulletin 2, Waco, Texas. Vaughn, C.C., and C. Taylor Impoundments and the Decline of Freshwater Mussels; a Case Study of an Extinction Gradient. Conservation Biology 13: Vidrine, M.F The historical distributions of freshwater mussels in Louisiana. Gail Q. Vidrine Collectables, Eunice, Louisiana. Watters, G.T Freshwater mussels and water quality: a review of the effects of hydrological and instream habitat alterations. Proceedings of the First Freshwater Mollusk Conservation Society Symposium 1999: