FISHES OF THE BUFFALO RIVER SYSTEM, WILKINSON COUNTY, SOUTHWESTERN MISSISSIPPI Mark A. Warren AiLUiti Community College, CedarPark, TX 78613 Robert C. Cashner New Department ofBiologicalSciences, University of Orleans, NewOrleans, LA 70148' AND Royal D. Suttkus Museum ofNaturalHistory, Tulane University, Belle Chasse, LA 70037 Abstract The occurrence and distribution ofthe fishes ofthe Buffalo River in south- western Mississippi were determined from two major surveys conducted from 1968-1971 and 1986-1991, as well as museum and literature records. In all, 95 species, from 20 families and 50 genera, were documented from the Buffalo River system. Cyprinids, centrarchids, poeciliids, fundulids, and clupeids were numerically dominant in both surveys. Longitudinal distribution of fishes in Buffalo River showed progressive downstream addition, with a large-scale re- placementin the lowerreaches. Monthly collections were made at six permanent stations from September 1986 to October 1987. Community similarity indices revealed relatively low faunal similarity between upper and lower sections of Buffalo River, and a strong pattern ofseasonal variation in the lower section of the river. Introduction The importance of the Mississippi River in fish biogeography has been dis- cussed in detail (Guillory, 1978, 1982; Grady et al., 1983; Conner and Suttkus, 1986). Fishes have been surveyed in several tributaries to the eastern part ofthe Mississippi River in Mississippi and Louisiana (Guillory, 1981, 1982; Grady et al., 1983; Cashner et al., 1979; Grady and Cashner, 1988; Ebert et al., 1985; Matthews, 1978), but only a few of the detailed results of these surveys have been published. Buffalo River (or Buffalo Bayou) is the lowermost eastern major tributary to the Mississippi River. Fish collections were made sporadically in the Buffalo River by R. D. Suttkus and students at Tulane University in the mid-1950's and early 1960's. The first comprehensive survey of the drainage was from November 1968 to July 1971, in which 68 collections were made at 17 sites located primarily in the upper and middle reaches of the river (Cashner et al., 1976). The present study included a second major survey conducted from Sep- tember 1986 to November 1991. During this period, 140 collections were made Tulane Studies in Zoology and Botany 29: 127-139. 1994. 127 128 Tulane Studies in Zoology and Botany [Vol. 29 at 60 different localities; 82 collections were made during monthly samples at 6 stations from September 1986 to October 1987. The two surveys represent a combined total of 208 collections at 60 localities. The purpose of this paper is to present a list of species for the Buffalo River drainage, to document the pattern of distribution of these species, and to assess seasonal variation in the fish assemblages at the six stations sampled monthly from 1986-1987. A paper currently in preparation will compare the results of the two major surveys and assess the changes in fish assemblages over a time span of nearly two decades. Study Area Except for extreme headwaters in Amite County, Buffalo River is within Wilkinson County, Mississippi (Figure 1). The spring-fed headwaters of the river originate in a forested area, 3.5 miles north ofCentreville, Mississippi. The river flows in a westerly direction, then north, increasing in size to a 4th-order stream (based on Strahler, 1957) as it receives runoff from small creeks and its first major tributary. Little Buffalo River. Buffalo Rivercontinues to flow north- ward, gradually increasing in width and depth. Near the vicinity of the Missis- sippi Highway 563 bridge, the river starts a northwesterly course and continues in this direction until it divides into several channels and forms a series ofbald cypress dominated swamps near Lessley, Mississippi. Then the river flows south- westerly to Lake Mary, an ox-bow lake formed from the Mississippi River, which is also connected to the Homochitto River to the north. After Lake Mary, Buf- falo River flows nearly due south, entering the Mississippi River near River Mile Figure 1.MapofBuffaloRiver,WilkinsonCounty,Mississippi,withcollectinglocalitiesindicated. 1994] Buffalo River Fishes 129 313, approximately 1.5 miles southwest of Fort Adams, Mississippi. The eleva- tion ofthe Buffalo River is 380 feet at the headwaters and 25 feet at the conflu- ence with the Mississippi River. The average gradient is 5.6 feet/mile and the watershed area is approximately 344 square miles. The river crosses several geological formations along its course. Headwaters are characterized by deep cut banks, a narrow channel, relatively clear water, and alternating pool, raceway, and riffle-type habitats. Here the stream exposes the alluvial sands and gravels of the Citronelle formation (Brown and Guyton, 1943; Fisk, 1951; Sibley, 1972). Sand is the dominant substrate throughout the upper headwaters, however, gravel is relatively abundant in riffle areas, and hard packed clays are found in some raceways. Farther downstream, the river traverses broad depositional Pleistocene terraces formed by Mississippi River sediments (Fisk, 1951; Sibley, 1972). The terraces, as well as the Citronelle for- mation to the east, are covered by loess soils (Snowden and Priddy, 1968). In this section, the river becomes larger, wider, more turbid, and mixed gravel substrates are replaced by shifting sand and mud. The lower reaches of Buffalo River cut through the recent alluvial floodplain of the Mississippi River (Fisk, 1944, 1951; Sibley, 1972). In the lower section, water levels fluctuate dramatic- ally and are directly influenced by the Mississippi River. Slow, turbid water flowing over soft mud substrate, rich in organic detritus, is characteristic ofthis reach. Terrestrial vegetation providing stream cover is abundant in the middle to upper regions ofBuffalo River. A mixed coniferous-hardwood forest makes up most of the stream canopy. Aquatic vegetation is occasionally present in the upper portions of the river, with blooms of floating pond-scum {Spirogyra sp.) common during the spring and summer. Upland pine forest is gradually re- placed by cypress-hardwood in the lower reaches of Buffalo River. Black willow {Salix nigra), eastern cottonwood {Populus deltoides) and bald cypress {Taxodium distichum) dominate. Aquatic vegetation is also abundant, with duck-weed {Lemna sp.), smart-weed (Polygonum sp.), duck-potato (Sagittaria latifolia), coon-tail (Ceratophyllum demersum) and American lotus {Nelumbo luted) most prevalent (Caplenor et al., 1968; Fassett, 1957). Materials and Methods At each locality, during both surveys, a 650-1300 foot longitudinal reach of the stream was seined for approximately 1.0-1.5 hours or until all of the major macrohabitats were sampled. Collections were made usingseines 10-50 feet long of 3/16 inch or 1/4 inch mesh. During the latter survey, in 1987, monofilament nylon gillnets, 150 feet x 6 feet with a 2 inch square mesh, were set at stations 5 and 6 on two different occasions (Figure 1). Monthly collections, from Sep- tember 1986 to October 1987, were made at six stations established from the upper reaches of Buffalo River to near its confluence with the Mississippi River (Figure 1). Specimens were fixed in the field with 10% formalin and stored for one week, then washed and transferred to 50% isopropyl alcohol for permanent storage. Nomenclature used in this paper follows Robins et al. (1991), except for the recognition ofthe families Fundulidae and Elassomatidae. All specimens collected during this study were deposited in the Vertebrate Collection at the University ofNew Orleans (UNOVC) or the Tulane Museum ofNatural History (TU). Detailed locations of all 60 collecting sites are given in the Appendix. 130 Tulane Studies in Zoology and Botany [Vol. 29 Analyses of Data Morisita's Index (!„,) and percent similarity index (PSI) were used to assess faunal similarity between stations 1-6. All species were included in the analysis following Matthews (1986a). Indices ofsimilarity have been widely used in com- paring sites within and between streams. Although the ranges ofvalues consid- ered by different authors to be high vary somewhat, we follow Matthews et al. (1988) in using values greater than 0.7 for PSI and 1^ as indicative ofrelatively high degree ofsimilarity between stations. Diversity indices (H') were calculated (to the log base 2) for stations 1-6 (Shannon and Weaver, 1962). Results A total of 71,559 specimens of 74 species in 17 families was recorded from the Buffalo River drainage in the 1968-1971 survey, and in the 1986-1991 sur- vey, 60,830 specimens of 88 species in 17 families were collected. Based on the two surveys, plus museum and literature records, the known ichthyofauna for the Buffalo River presendy stands at 95 species in 20 families (Table 1). Cyprinidae was the dominant family, both in number ofspecies represented (26% of total) and individuals (74% of total) collected during the two surveys. The three numerically dominant species, Cyprinella camura, Notropis longirostris, and Cyprinella venusta, made up 54% ofthe total specimens. The cyprinids were followed by Fundulidae and Poeciliidae (5% each) and Centrarchidae (6%) in number of individuals. The Percidae, with 17%, and the Centrarchidae, with 14%, ranked second and third, respectively, behind the cyprinids in number of species represented. During the survey of6 permanent stations in 1986-1987, 82 collections were made yielding 79 species in 15 families (Table 2). There was an obvious change in the numerical dominance of species between the upper, middle, and lower reaches ofthe Buffalo River (Table 2). At stations 1 and 2, Cyprinella camura and Notropis longirostris were the most abundant and accounted for 54% ofthe speci- mens captured. At stations 3 and 4, the numerical abundance ofCyprinella cam- ura and Notropis longirostris decreased, and Cyprinella venusta and Hybognathus nuchalis increased. These two species comprised 52% of the total specimens collected at stations 3 and 4, compared with 26% for Cyprinella camura and Notropis longirostris. In the lower portions of the river, at stations 5 and 6, Dorosomapetenense, Gambusia affinis, and Lepomis macrochirus were the most abun- dant forms taken. There was virtually no similarity between the upper and middle stations 1-4, (Figure 1) and the lower ones (5 and 6, Table 3). I^^ values among the upper four sites ranged from 0.34-0.94. In all but a few cases the PSI estimates were lower than I^, as predicted by Linton et al. (1981). Only stations 1 and 2 and 3 and 4 had both I^ and PSI values suggesting relatively high faunal similarity. Based on the I^, alone, stations 1 and 2 and 1 and 3 could be regarded as highly similar to each other. Stations 5 and 6 were the only other paired stations that had Ij„ values near 0.70. The most dissimilar adjacent stations were 4 and 5 (I^^ =0.20; PSI =0.17), which had only 40% of their species in common. Cyprinella venusta and Hybog- nathus nuchalis accounted for 56% of the specimens taken at Station 4, but only 5% at Station 5. Notropis texanus (11%) and Lythrurusfumeus (7%) were the most common cyprinids at Station 5, and slow-water forms, such as Gambusia affinis, Labidesthes sicculus, and Lepomis macrochirus, made up nearly 50% of the catch (compared to about 7% at Station 4). 1994] Buffalo River Fishes 131 The number of species per site, for the six permanent stations, increased gradually from 30 to 37 downstream from Station 1 to Station 4, which was located near the end of the lower middle reaches of Buffalo River (Table 4). The number of species increased to 47 at Station 5 and was virtually the same at Station 6. Species diversity was highest at Station 5 (H' = 2.56); values at the other 5 stations varied from 2.02 to 2.15. Seasonal Variatioyi at Six Stations. Similarity across seasons in the fish assemblages at the six stations was examined for species collected monthly by seines from October 1986 to Sep- tember 1987. The year was divided into four seasons, autumn (September- November), winter (December-February), spring (March-May), and summer (June-August) (Table 5). Streamwide, the species richness and abundance were highest in the summer and autumn, with 61 species and 12,352 specimens, and 63 species and 8190 specimens, respectively. Fifty-eight species and 7398 speci- mens were taken in spring, and the winter season yielded 3188 specimens, rep- 45 resenting species. The greatest stability in fish assemblages for the 12-month period occurred at Station 2 (Table 5). The !„, values among all seasons were high for this station (0.80-0.93). For Station 1, autumn-winter and winter-spring I„, valuesaveraged 0.90, but the summer assemblage was much more variable, with I^^ for spring- summer of 0.60 and 0.67 for summer-autumn. The faunal similarity at the middle sites, stations 3 and 4, was also highest between autumn, winter, and springsamples (x = 0.75) and lowestbetween the summer and theotherseasons (x = 0.48). The lower stations, 5 and 6, were the most variable between seasons. Only autumn and winter samples at Station 5 had high similarity (0.92). The comparisons of faunal assemblages for the other seasonal pairings at these two stations ranged from 0.04 — 0.61 (x = 0.32). The greatest seasonal variability was at Station 6, where \^ values for the four seasons averagedjust 0.25. Longitudinal Distribution ofFishes. Species richness in Buffalo River increases from the headwaters to the mouth. Thirty species were recorded at Station 1, and 51 by Station 4, where the river channel becomes noticeably wider and deeper (Table 4). A rather striking change in the fish fauna occurs between stations 4 and 5, where the river takes on a more distinctive lowland character. Stations 5 and 6 had the highest species number, with a total of47 and 45 species, respectively. At these two lower stations, 28 species not collected in the upper and middle portions were added, bringing the total for the six permanent stations to 79. Only six species appeared to be restricted to the upper reaches, and 14 others were more or less confined to the upper and middle portions, stations 1-4, of the stream course (Table 2). A group of 35 species was found primarily in the lower reaches, at stations 5 and 6, and 13 species were distributed throughout all of the six stations or were absent from only one site (Table 2). Discussion The general pattern of species addition has been documented in many studies for rivers and streams in the eastern and central United States (e.g., Larimore and Smith, 1963; Sheldon, 1968; Jenkins and Freeman, 1972). The Buffalo River exhibits a pattern of increased species richness downstream ac- 132 Tulane Studies in Zoology and Botany [Vol. 29 Table 1. Abundance of fish species recorded from Buffalo River, Mississippi, in 1968-1971 and 1986-1991 surveys. Asterisk indicates species based on catch by commercial fishermen or museum record. NumberofSpecimens FamilyandSpecies 1968-1971 1986-1991 Total Petromyzontidae(lampreys) Ichthyomyzongagei 15 Lampetraaepyptera Polyodontidae(paddlefishes) Polyodonspathula* Lepisosteidae(gars) Lepisosteusoculatus Lepisosteusosseus Lepisosteusplatostomus Amiidae(bowfins) Amiacalva Anguillidae(freshwatereels) Anguillarostrata Clupeidae(herrings) Alosachrysochloris Dorosomacepedianum Dorosomapetenense Cyprinidae(carps&minnows) Campostomaanomalum* Cyprinellacamura Cyprinellalutrensis Cyprinellavenusta Cyprinuscarpio Hybognathushayi Hybognathusnuchalis Luxiluschrysocephalus Lythrurusfumeus Lythrurusumbratilis Macrhybopsisstoreriana Nocomis leptocephalus Notemigonuscrysoleucas Notropisatherinoides Notropisblennius Notropisbuchanani Notropislongirostris Notropisshumardi Notropistexanus Notropisvolucellus Notropiswinchelli Opsopoeodusemiliae Pimephalesnotatus Pimephalesvigilax Semotilusatromaculatus Catostomidae(suckers) Carpiodescarpio Erimyzonoblongus Hypenteliumnigricans Ictiobusbubalus Minytremamelanops Moxostomapoecilurum Ictaluridae(catfishes) Ameiurusmelas Ameiurusnatalis Ictalurusfurcatus Ictaluruspunctatus Noturusgyrinus Noturusmiurus 1994] Buffalo River Fishes 133 Table 1. (Continued) NumberofSpecimens FamilyandSpecies 1968-1971 1986-1991 Total Notiuusphaeus 277 Pylodiclisolivatis Esocidae(pikes&pickerels) Esoxamei'icaniL'i* Aphredoderidae(pirateperches) Aphredodermsayaiius Fundulidae(killifishes) Fiindiilitscatenatus Funduluschrysotus Funduliisdispar Fundulusnolalus FundulusuUvaceus Poeciliidae(livebearers) GamhiLsiaaffinis Atherinidae(silversides) Labidesthessicculus Menidia bejyllina Syngnathidae(pipefishes) SyngjiathusscuvelU Percichthyidae(temperatebasses) Morone chrysops Morone mississippiensis Moronesaxatilis Centrarchidae(sunfishes) AmblopUtesariommus Lepomiscyanellus Lepomisgulostis LepomisImmilis Lepomismacrochirus Lepomismegalotis Lepomismicrolophus Lepomispunclatus Lepomissymmetricus Micropteruspunctulatus Micropterussalmoides Pomoxisannularis Pomoxisnigromaculatus Elassomatidae(pygmysunfishes) Elassomazonalum Percidae(perches&darters) Ammocryptabeani Etheostomachlorosomum Etheostomafusiforme Etheostomagranle Etheostomahistrio Etheostomalynceum Etheostomapan'ipinne Etheostomaproeliaire Etheostomastigmaeum Etheostomaswaini Etheostomawhipplei Percinacaprodes Percinasciera Percinashumardi Percinavigil Stizostedioncanadense Sciaenidae(drums) Aplodinotusgrunniens 134 Tulane Studies in Zoology and Botany [Vol. 29 Table2. Speciesand numberofspecimenscollectedduringthe 1986-1987surveyatsixpermanent stations in Buffalo River, Mississippi. Station 3 4 6 Total Ichthyomyzongagei Lampetraaepyptera Lepisosteusoculalus L.osseus L.platostomus Alosachrysochloris Dorosomacepedianum D.petenense camura Cyprinella C. lutrensis C.venusta Cyprinuscarpio Hybognathushayi H.nuchalis Luxiluschrysocephalus Lythrurusfurneus L.umbratilis Nocomisleptocephalus Notemigonuscrysoleucas Notropisatherinoides N.blennius N. longirostris N.shumardi N.texanus N.volucellus N.winchelli Opsopoeodusemiliae Pimephalesnotatus P.vigilax Semotilusatromaculatus Carpiodescarpio Erimyzonoblongus Hypenteliumnigricans Ictiobusbubalus Minytremamelanops Moxostomapoecilurum Ameiurusnatalis Ictalumspunctatus Noturusgyrinus N.miurus N.phaeus Aphredoderussayanus Funduluscatenatus F.chrysotus F.dispar F. notatus F.olivaceus Gambitsiaaffinis Labidesthessicculus Menidia beryllina Syngnathusscovelli Morons chrysops M. mississippiensis M.saxatilis 'Lepomiscyanellus L.gulosus L.humilis 1994] Buffalo River Fishes 135 Table 2. (Continued) Station '^ 4 fi Total L. macrochinis 21 L. megalulis L.microlophus L.punctatiLs L.symmetricus Micropteruspunctulatus M.salmoides Pomoxisannularis P.nigromaculatus Ammocjyptabeani Etheoslomachlorosomum E.gracile E.lynceum E.pannpinne E.proeliare E.stigmaeum E.swaiyii E.whipplei Percinacaprodes P.sciera P.vigil Aplodinotiisgrunniens 136 Tulane Studies in Zoology and Botany [Vol. 29 Table 5. Seasonal similarity (I,„) for the six permanent stations, Buffalo River, Mississippi, during 1986-1987. Station