Lotic freshwater mussels (Family Unionidae) of the Angelina and Davy Crockett National Forests of east Texas.

Abstract. -- Ten streams located in the Davy Crockett National Forest and five streams located in the Angelina National Forest of eastern Texas were surveyed during 1995 and 1996 to determine species composition and abundance of freshwater mussels. Nine species of freshwater mussels were collected from 10 of the study streams; five of the streams contained no mussels or only shells of dead specimens. Species found as well as their abundance and habitats are discussed.

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Among the 52 species of freshwater mussels (Family Unionidae) reported in Texas, 17 are listed as threatened, endangered, or of special concern (Williams et al. 1993) and one is listed as federally endangered. B. A. Steinhagen Reservoir and the adjacent Neches and Angelina rivers, located in eastern Texas, still support one of the most abundant and diverse populations of freshwater mussels remaining in Texas (Howells 1996). The 65,360-hectare Davy Crockett National Forest (DCNF) lies in the Neches and Trinity river basins with the Neches River serving as the eastern boundary (Fig. 1). The 62,422-hectare Angelina National Forest (ANF) lies in the Neches River basin, and on the north and south sides of Sam Rayburn Reservoir, an impoundment of the Angelina River (Fig. 2). These forests, along with most of eastern Texas, are characterized by slow-moving streams with normally dependable volumes of water (Neck 1986). Very little research has been conducted on the majority of these streams. This study establishes base-line data of the bivalve fauna of the small streams located in the Davy Crockett and Angelina National Forest.

STUDY AREA

Fifteen previously unclassified streams, which are tributaries of either the Neches or Angelina rivers, were sampled during this study. Ten streams located in the DCNF selected by the U.S. Forest Service (USFS) for study included: (1) Alabama Creek, fourth-order stream, southeast corner of DCNF, with sand-gravel-detritus substrate, sampled 9 June 1996 at the terminal end of Forest Road (FR) 523 in forest compartment 101; (2) Austin Branch, third-order stream, northwest corner of DCNF, with deep-shifting sand substrate, sampled 3 September 1996 at the terminal end of FR 544-A in forest compartment 2; (3) Camp Creek, third-order stream, northern DCNF, deep, shifting sand substrate, sampled 10 September 1995 beginning at FR 511 bridge; (4) Cochino Bayou, fifth-order stream, central portion of DCNF, loam-detritus substrate, sampled 1 October 1995 at FR 582 bridge; (5) Hackberry Creek, third-order stream, eastern DCNF, sampled 1 October 1995 at two locations (a) Farm to Market Road 2262 bridge, clay overlain by thick sand substrate, erosion due to cattle activity, (b) Farm to Market Road 2501 bridge, hard pan clay substrate with occasional sandbars; (6) Hagar Creek, third-order stream, central portion of DCNF, loam-detritus substrate with outcroppings of pebbles and small cobble, sampled 24 September 1995 at FR 582 bridge in forest compartment 50; (7) Hickory Creek, fourth-order stream, northern DCNF, loam-detritus substrate, sampled 10 September 1995 at FR 511 bridge; (8) Lynch Creek, intermittent first-order stream, western DCNF, sand-loam substrate, sampled 28 November 1994 at Farm Road 2781 bridge in forest compartment 70; (9) Piney Creek, fourth-order stream, drains large portion of southeastern DCNF, loam-clay substrate, sampled 9 July 1995 beginning at FM 2262 bridge near forest compartment 98; (10) Sandy Creek, first-order stream, northern DCNF, loam-sand substrate, sampled 10 September 1995 at FR 307 bridge near forest compartment 17.

[FIGURE 1 OMITTED]

[FIGURE 2 OMITTED]

Five previously-unclassified streams were chosen for study from ANF. These included: (1) Big Creek, third-order stream, southern ANF, clay substrate, sampled 25 June 1995 at Forest Road 303 bridge near compartment 94; (2) Graham Creek, fourth-order stream, southwestern ANF, pocketed clay substrate with silt deposits in the pockets, sampled 25 June 1995 at Forest Road 314 bridge near forest compartment 98; (3) Harvey Creek, second-order stream, northeast ANF, loam-clay substrate, sampled 8 October 1995 at Forest Road 319 bridge, (4) Sandy Creek, first-order stream, northeast ANF, sand-detritus substrate, sampled on 18 June 1995 at Forest Road 307 bridge near forest compartment 18; (5) Turkey Creek, third-order stream, northeast ANF, gravel substrate, sampled 8 October 1995 at terminal end of Forest Road 342.

MATERIALS AND METHODS

Each study stream was sampled for two hours by wading and hand-collecting. During sampling, representative specimens of each species found were placed in large, plastic containers containing 95% ethyl alcohol. All other mussels were counted, identified, and immediately returned to the substrate. Dead mussels or shells collected were placed in labeled plastic bags. Upon transport back to the laboratory, preserved specimens were placed in wide-mouth glass jars with fresh 95% ethyl alcohol. Shells from dead mussels were cleaned, dried, and sprayed with a nonglossy acrylic sealer to prevent the epidermis from flaking. Specimens were identified to species using various taxonomic keys (Pennak 1989; Cummins & Mayer 1992; Vidrine 1993). Voucher specimens have been deposited in the Stephen F. Austin State University Invertebrate Museum, Nacogdoches, Texas.

RESULTS

One hundred ninety one individuals representing nine unionid species and numerous Corbicula fluminea (Family Corbiculidae) were collected from the streams of the Davy Crockett and Angelina National Forest Tables 1 & 2). Ten of the streams sampled contained living mussel populations, while five did not. Live mussels were not found in Austin Branch, Camp Creek and Lynch Creek in the Davy Crockett National Forest, nor in Harvey Creek and Turkey Creek in the Angelina National Forest. It is believed that the substrate, hydrology, or both, of these streams were not suitable to support freshwater mussels.

Piney Creek (DCNF) contained the greatest number of mussel taxa with six species present. Uniomerus declivus was the most abundant species and accounted for 51% of the live mussels collected from this stream. This species was also the most abundant throughout the survey area and accounted for 48% of the mussels counted, and was found in six of the streams sampled. Lampsilis hydiana was the second most abundant species in Piney Creek and accounted for 21% of the mussels counted. Lampsilis hydiana was also the second most abundant species found throughout the survey area and accounted for 21% of the mussels counted, and was collected from four of the streams sampled. The third most abundant species in Piney Creek was Villosa lienosa which accounted for 19% of the mussels found. Glebula rotundata, Pyganodon grandis and one living individual of Lampsilis teres were also collected from Piney Creek. This was the only stream in which these three species were present.

Cochino Bayou (DCNF) contained the second greatest number of mussel taxa with five species present. Lampsilis hydiana was the most abundant species collected from this stream and accounted for 50% of the mussels counted. Ligumia subrostrata and Toxolasmus texasensis were second in abundance with each accounting for 19% of the mussels counted. One individual of Uniomerus tetralasmus was also collected from this stream.

Big and Sandy creeks (ANF) contained three species each. Uniomerus declivus was the most abundant species collected from both streams accounting for 68% and 46%, respectively, of the mussels collected. Toxolasmus texasensis was also collected from both of the streams and was the second most abundant species in Sandy Creek accounting for 42% of the mussels counted. In addition, four individuals of L. subrostrata were collected from Big Creek and three individuals of U. tetralasmus were collected from Sandy Creek.

No living unionids were collected from the initial study site of Hackberry Creek. However, one living individual of U. tetralasmus and one living individual of U. declivus were collected from a second study site.

Alabama, Hagar, Hickory and Sandy creeks (DCNF), as well as Graham Creek (ANF) each contained only one living species of unionid. Uniomerus declivus was the only living species collected from Alabama and Hagar creeks. Villosa lienosa was the only species collected from Sandy Creek, while Graham and Hickory creeks only contained L. hydiana.

The exotic mussel Corbicula fluminea was collected from two of the streams sampled. It was found in abundance in Hickory Creek and occasionally in Cochino Bayou.

DISCUSSION

Piney Creek and Cochino Bayou contained the greatest number of mussels species of any of the study streams. Twidwell et al. (1992) identified Piney Creek as the South Central Plains ecoregion's least impacted stream. Also, an ichthyological study conducted by Kelly (1995) found that these two streams had the highest Index of Biotic Integrity (IBI) scores of the ten study streams in the Davy Crockett National Forest. The IBI is a broadly-based biological index which has been shown to be able to assess many man induced stresses, such as sewage (Leonard & Orth 1986), siltation (Berkman & Rebeni 1987), and many other chemical effects. The freshwater mussel's reproductive strategy includes a parasitic relationship with a fish host. Upon release from the female mussel, the glochidia must attach to a suitable host species within a few hours or days, depending on the mussel species, or they will die. Mussel literature indicates only three North American unionids may transform to the juvenile stage without any host, and another species uses a salamander. Therefore, in order to sustain a healthy and diverse mussel population, healthy fish populations are essential.

The streams of the national forest were dominated by mussel species which are able to tolerate low flow conditions often found in small streams. Uniomerus declivus and U. tetralasmus are able to withstand dewatering and drought (Neck & Metcalf 1988). Uniomerus declivus was frequently found in less than 5 cm of water and occasionally above the water line. Ligumia subrostrata is sometimes found with Uniomerus in small, shallow water bodies where other mussels may not occur (Howells et al. 1996).

Hackberry Creek (DCNF) is a prime example of the greatest threat to East Texas mussel populations. East Texas has fragile sandy soils and even minor modification of terrestrial vegetation results in extensive sand deposition in streams and rivers (Howells 1996). This deposition smothers existing mussels and creates an unsuitable substrate for future mussel populations. The initial sample site on Hackberry Creek was located in an area where the stream ran through pasture land and cattle activities had removed most of the vegetation from the stream banks. The water was highly stained from cattle waste and the substrate consisted of clay overlain with a thick layer of sand. No mussels were found at this site. The second site sampled on Hackberry Creek was located upstream from the cattle activity and had vegetated banks, clear water, and a hard pan clay substrate with occasional small sandbars. Live specimens of U. declivus and U. tetralasmus were collected from this location.

Piney Creek contained several mussels species generally not found in small East Texas streams. Glebula rotundata is typical of lower reaches of rivers just above brackish waters and is rarely found this far inland (Howells 1996). It is interesting to note that individuals with white nacre and individuals with purple nacre were both taken from this stream.

Pyganodon grandis was also another species not typical of small streams. This species does well in impoundments generally preferring no-flow conditions (Oesch 1984). It was found in larger pools of Piney Creek.

CONCLUSIONS

This study would indicate that the small streams of the Angelina and Davy Crockett National Forest still support freshwater mussel populations. However, this study was intended to provide initial base-line data for future studies. Further study of these streams and other streams in this area are needed to further document the freshwater mussel species present.

Table 1. Species and number of individuals of freshwater mussels (family
Unionidae) collected from the Davy Crockett National Forest, Texas.

Species              Alabama  Austin  Camp  Cochino  Hackberry  Hagar

Glebula rotundata       0       0      0       0        0         0
Lampsilis hydiana       0       0      0       2        0         0
Lampsilis teres         0       0      0       0        0         0
Ligumia subrostrata     0       0      0       3        0         0
Pyganodon grandis       0       0      0       0        0         0
Toxolasmus
   texasensis           0       0      0       2        0         0
Uniomerus declivus      4       0      0       0        1         6
Unionmerus
   tetralasmus          0       0      0       1        1         0
Villosa lienosa         0       0      0       0        0         0

Species              Hickory  Lynch  Piney  Sandy

Glebula rotundata       2       0      4      0
Lampsilis hydiana       0       0     23      0
Lampsilis teres         0       0      1      0
Ligumia subrostrata     0       0      0      0
Pyganodon grandis       0       0      4      0
Toxolasmus
   texasensis           0       0      0      0
Uniomerus declivus      0       0     55      0
Unionmerus
   tetralasmus          0       0      0      0
Villosa lienosa         0       0     20      1

Table 2. Species and number of individuals of freshwater mussels (family
Unionidae) collected from the Angelina National Forest, Texas.

Species                Big  Graham  Harvey  Sandy  Turkey

Glebula rotundata       0      0      0       0      0
Lampsilis hydiana       0     14      0       0      0
Lampsilis teres         0      0      0       0      0
Ligumia subrostrata     4      0      0       0      0
Pyganodon grandis       0      0      0       0      0
Toxolasmus texasensis   3      0      0      10      0
Uniomerus declivus     15      0      0      11      0
Uniomerus tetralasmus   0      0      0       3      0
Vilosa lienosa          0      0      0       0      0

LITERATURE CITED

Berkman, H. E. & C. Rabeni. 1987. Effect of siltation of stream fish communities. Env. Biol. Fishes 18:285-294.

Cummins, K. S. & C. A. Mayer. 1992. Field guide to freshwater mussels of the midwest. Illinois Natural History Survey, 194 pp.

Howells, R. G. 1996. Freshwater mussels of B.A. Steinhagen Reservoir and the adjacent Neches River drainage. Texas Parks and Wildlife Department Inland Fisheries, Ingram, 22 pp.

Howells, R. G., R. W. Neck & H. D. Murray. 1996. Freshwater mussels of Texas. Texas Parks and Wildlife Department, Austin, 218 pp.

Kelly, J. P. 1995. An ichthyological survey of ten streams in the Davy Crockett National Forest. Master of Science thesis. Stephen F. Austin State University, Nacogdoches, Texas.

Leonard, P. M. & D. J. Orth. 1986. Application and testing of an index of biotic integrity in small, cool water streams. Trans. Amer. Fish Soc. 115:401-415.

Neck, R. W. 1986. Freshwater bivalves of Lake Tawakoni, Sabine River, Texas. The Texas Journal of Science 38:241:249.

Oesch, R. D. 1984. Missouri naiades: A guide to the mussels of Missouri. Missouri Department of Conservation, Jefferson City, 270 pp.

Pennak, R. W. 1989. Fresh-water invertebrates of the United States, 3rd ed. John Wiley and Sons, Inc., New York, 569-601 pp.

Twidwell, S. R., J. R. Davis, C. W. Bayer, R. Kleinsaser, G. Linam, K. Mayes & E. Hornig. 1992. Texas aquatic ecoregion project: an assessment of least disturbed streams. Unpublished manuscript. Texas Water Commission, Austin, 406 pp.

Vidrine, M. F. 1993. The historical distributions of freshwater mussels in Louisiana. Gail Q. Vidrine Collectibles, Eunice, Louisiana, 225 pp.

Williams, J. D., M. L. Warren, K. S. Cummings, J. L. Harris & R. J. Neves. 1993. Conservation status of freshwater mussels of the United States and Canada. Fisheries. 18(9):6-22.

Dana M. Feaster

Department of Biology, Stephen F. Austin State University

Nacogdoches, Texas 75962