The American Midland Naturalist Published Quarterly by the University of Notre Dame, Notre Dame, Indiana

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1 The American Midland Naturalist Published Quarterly by the University of Notre Dame, Notre Dame, Indiana Vol. 109 JANUARY, 1983 No. 1 The Response of Fishes to Periodic Spring Floods in a Southeastern Stream STEPHEN T. ROSS Department of Biology, Box 5018, University of Southern Mississippi, Hattiesburg 39401, and University of Oklahoma Biological Station, Star Route B, Kingston, and JOHN A. BAKER Department of Biology, Box 5018, University of Southern Mississippi, Hattiesburg ABSTRACT: Movement of fishes onto a fringing floodplain was siudied by seining and trapping during live spring floods. We collected 26 species frotn the inundated floodplain; the known channel fauna is 42 species. Species numerically dominant on the floodplain were Fundulus olivaceus, F. notti, Gambusia affinis, Notropis welaka, N. texanus, N. rose:pinnis, Lepomis macrochirus, L. cyanellus and L. marginalia. Catch-per-effort in traps was generally greatest on the upper floodplain during the day and greatest nearer the channel at night. Night activity of fishes on the floodplain was apparently low. Several species, which we term flood-quiescent forms, were common in the channel (e.g., Lepomis megalotis and Percina nigrofasciata) but did not exploit the floodplain. Activity (as catch per trap-hour) of P. nigrofasciata was negatively correlated with floodinduced turbidity. A flood-exploitative species, Notropis texanus, had higher population abundance during 3 high-flow years than in 3 low-flow years, suggesting that spring flooding may exert significant control over fish community structure. INTRODUCTION Periodic flooding is characteristic of most lotic systems. Based on channel morphology and gradient, floods may be erosive and thus potentially destructive to the stream habitat, or depositional, exhibiting "creeping flow" and being generally nondestructive to channel morphology (Welcomme, 1979). Most studies of the effects of flooding on aquatic organisms have treated erosive floods (e.g., Paloumpis, 1958; John, 1963, 1964; Greenfield el al., 1970; Seegrist and Gard, 1972; Hanson and Waters, 1974; Hoopes, 1975; Harrell, 1978), in which severe faunal disruption often occurs. Adaptations of organisms to erosive floods are either for surviving high flow rates th - FOUilf behavioral or morphological moslifications, or for life history characteristics allowing rapid recolonization. - Few studies have addressed the effects of nondestructive flooding on North - American streams. Such floods occur inonw ḡradient systems in which floods are primarily characterized by lateral expansion rather than increases in deptid (Welcomme, 1979). While lateral expansion of rivers onto floodplains is best developed in tropical areas (Welcomme, 1979), many North American streams, especially in the southeastern United States, also show (or showed prior to levee construction and channelization) well-developed fringing floodplains (Viosca, 1927; Gunter, 1957; Bennett, 1958; Guillory, 1979). Such natural floodplains may be seasonally inundated. Forbes (1925) pointed out the importance of inundated floodplains as breeding grounds and foraging areas for fishes and aquatic invertebrates. Wickliff (1945) recorded movement of fishes onto an inundated floodplain. Starrett (1951) determined that certain minnows spawn in backwater areas and suggested that flooding was an important factor controlling minnow populations. Bennett (1958) believed that periodic flooding of the Mississippi and Illinois rivers was beneficial to largemouth bass populations. Guillory (1979) found that a number of Mississippi River species used inundated floodplains as

2 ! t 2 THE AMERICAN MIDLAND NATURALIST 109( 1) feeding or nursery areas, thus emphasizing the importance of floodplains to river 1 fishes. This study assesses lateral movement patterns of stream fishes onto a floodplain during periodic, nondestructive spring floods. Specifically, we ask; (1) if species corn : position of the floodplain was a random sample of the known channel ichthyofauna; ts (2) ' if did l changes occurred in the use of the floodplain by fish species, and (3) if there were did changes in the location of fishes on the floodplain. STUDY AREA The study site was in southeastern Mississippi on the upper Black Creek system which lies entirely within ihe Pine Hills physiographic - region of the Gulf Coast Plain (Cross et al., 1974). From its source in Jefferson Davis County, approximately 50 km NW of Hattiesburg, the creek flows southeasterly through moderately hilly terrain (elevations m above mean sea level) to its confluence with the Pascagoula ' River. The study site was immediately upstream from Mississippi Hwy. 589 in Lamar County. The creek at this point averages.10 m wide and is characterized during normal flow by clear, but slightly brown-stained water (mean JTU = 14.9; s = 6.09), low ph (R. 6.2; s =.37), and low conductivity (51 = 28.4 Amhos/cm; s ). Annual mean discharge, as calculated from channel morphology (Leopold et a/., 1964) was 6.8 m 3 s -1. The substrate was sand, often overlain with silt or leaf litter, and submerged aquatic, vegetation (primarily Spargantum americanum).lextensive areas of open grassy meadow and woods characterized the floodplainj Four small permanent ponds were also located 1 in the floodplain and were confluent with the creek during flooding. i Black Creek at the study site has an upstream drainage area of 199 km 2. The region! averages 146 cm annual rainfall, principally from December to April, and also in July (Fig. IA). During winter and spring the flow rate closely parallels rainfall. In July, ' however, flow rates remain low despite heavy rains, perhaps because of increased i evaporation and transpiration rates (Fig. 1B). Annual flow rates for Black Creek near Brooklyn, Miss., were available only from 1972 to 1979; however, annual flow regimes of Bowie Creek (at Hattiesburg in Forrest County) were available from 1939 (U.S. Geological Survey, ). Since Bowie Creek has approximately the same drainage pattern and area as Black Creek at the study area, and the gauging sites are separated by only 37 km, we have used data from Bowie Creek to substantiate annual flow patterns. Due to the high correlation of flow rates for these streams (r = 0.85; P <.01; N - 96 monthly means) Figure IC adequately re resents the long-term flow pattern for Black Creek. The system is characterized b elevated flow rates in February, March and April, followed by low flow periods from June to Octoberj Another peak in flow occurs in December. METHODS Quarterly or semiannual collections (N = 17) were made at the study site from 1 September 1975 to January 1981 as part of a baseline monitoring program. Details of ; collecting procedures are in Baker and Ross (1981). All such collections were during ; nonflood periods, using a 6.1 m x 1.2 m, 3-mm mesh bag seine. The flood study began 1 in the spring (1-6 April) of 1976 and continued during spring floods of 1977 (31, March-2 April; April; May) and 1979 (23-25 March). In 1978 only control. (nonflood) collections were madetwe considered flooding to occur when flow exceeded :. the stream banksjduring flooding the seine could only be used around the periphery of ' the floodplain; channel collections by seining were not possible. To assess fish : movements in the channel and the deeper sections of the floodplain we used 3-mm ; mesh, hardware-cloth minnow traps. The traps were rectangular, 40 cm x 20 cm x 10 cm, and had a single funnel opening approximately 5 cm in diam. Traps were con-, nected approximately 1 m apart by rope in lines of 10 traps each, and were set in ' predetermined locations in the main channel and on the floodplain (Fig. 2). During floods, traplines were checked and reset twice daily near dawn and dusk until the water, receded to the normal channel.

3 1983 Ross & BAKER: FISH RESPONSE TO FLOODS We measured temperature, turbidity, and ph during both normal and flood collections. Turbidity was measured in Jackson Turbidity Units (JTU) with a Hach DR-EL field kit, and ph was determined in the field with a Corning Model 3 portable ph meter. During each flood collection water height was recorded from a reference point on the Mississippi Hwy. 589 bridge. Measurements of fishes are in mm standard length. RESULTS From September 1975 to January 1981, 5389 fishes of 42 species were taken by seining in the main channel area of Black Creek at the study site (Table 1). These collections were made during normal flow. The channel ichthyofauna was dominated numerically (59%) by cyprinids, with Notropis texanus and N. roseipinnis comprising 27 and 26%, respectively. Cyprinodontids, primarily Fundulus otivazeus, comprised 12% of the ichthyofauna, followed by centrarchids which comprised 10%. Lepomis macrochirus (4 % ) and L. megalotis (2.7%) were the dominant centrarchids. Darters (Percidae) were also numerous, comprising 9% of the catch. We collected 1411 fishes of 33 species from the channel and floodplain during periods of spring floods; all but three species, Amia calva, Notemigonus cgsoleucas and Noturus funebtis, were represented in the normal flow collections (Table 1). Twenty-six species were taken on the floodplain, nine from both floodplain and channel, and 17 from the floodplain only. As expected, different species were captured by trapping and seining. Thirteen species were collected by trap only, nine species by seining only and 11 by both methods. FLOW RATE (161 5/mIc ) to , ,,..,..._...-. S. N1N \\ N..,,, s ' _ */ AVERAGE MONTHLY RAINFALL (Cm) A A 0 Fig. 1. A. Average monthly rainfall for southeastern Mississippi; B. annual flow rates for Black Creek based on 8 years of data (R±s); C. annual flow rates for Bowie Creek based on 41 years of data (ir ±s)

4 4 THE AMERICAN MIDLAND NATURALIST 109(1) To test the hypothesis that species composition of the floodplain "community" was a random subset of the channel community, we used Morisita's Index (1m) of community similarity which is based on Simpson's dominance index (Horn, 1966; Brower and Zar, 1977). The index ranges from 0, indicating complete distinctness to approximately 1, for identical samples. In this analysis both trap and seine data for floodplain fishes were combined and compared with the trap and seine collections from the river channel. The floodplain ichthyofauna showed only a moderate difference from the channel ichthyofauna, as Im was 0.6. [fishes which exploited the floodplain were numerous cyprinids and centrarchids, Fundulus olivaceus and F. noiti, Gambusia affinis, Noturus gyrinus, Etheostoma swami and two esocids (Table 1).]Numerically dominant cyprinids on the floodplain were Notropis welaka, N. texanus and N. roseipinnis. Lepomis macrochirus, L. cyanellus and L. marginatus were the most abundant centrarchids on the floodplain. Lepomis megalotis, which was common in the channel, was not collected on the floodplain. [Most of the species collected on the floodplain were represented by both juveniles and adults; however, larger-bodied species on the floodplain such as Esox americanus (Ft = 65.7; range = 47-87), Lepomis macrochirus (5t" = 34.7; range = 20-50), L. cyanellus - 37; range = 24-51) and L. marginatus (R = 50.7; range 29-74) were all juveniles based on published minimum reproductive size(carlander, 1969, 1977), with the possible exception of L. marginatus. The size distribution of these species reflects some sampling bias since larger fishes could not enter the traps and would also be more efficiept at avoiding the seine. tile distinction between the floodplain "community" and the channel "community" is more evident when only channel and floodplain trapline, rather than seine, collections are considered. For this comparison Im = 0.06, indicating essentially different faunas being sampled in the two areas. The number of species from each area were however, highly similar with 16 taken from the channel and 17 from the floodplainl Trap data for day-night channel and floodplain comparisons are presented as atch/trap-hour for the eight most common species (Fig. 3). Total trap hours for day/night channel collections and day/night floodplain collections were 1000, 2250, 1305 and The catch-per-effort (C 1 ) of Percina nigrofasciata was greatest during the daytime channel collections and dropped greatly in the channel at night. Conversely, 0-approx. mean high flooding extent Fig. 2. Channel and floodplain trapline locations at the Black Creek study area. C = channel traplines; N = near-channel traplines; M = midfloodplain traplines; U = upper floodplain traplines

5 TAist.F 1. - Fishes collected from the channel and floodplain of Black Creek, Mississippi, by seining and trapping during normal flow and flood conditions ( ) Species Channel Floodplain c.c.1 CA) Normal flow Flood conditions Flood conditions Seine Trap Trap Trap Seine Petromyzontidae Ichthyomyzon gagei Amiidae Amia calva 1.3 Anguillidae Anguilla rostrata 1.02 Esocidae Esox niger E. amerzcanus Cyprinidae Notemigonus crysoletwas 4.6 Ericymba buccata 3.06 Notropis emiliat N. voluzellus N. venustus N. we/aka N. longirostrz:s 4.07 N. texanus N. roseipinnis Catostomidae Erimyzon tenuis Hypentelium nigricans 3.06 Minytrema mtlanops Ictaluridae Noturus leptacanthus N. gyrinus N. nocturnus N. funthris Atherinidae Labiliesthes sicculu.s & BAKER: FISH RESPONSE TO FLOODS

6 Table I. Continued Species Channel Floodplain Normal now Flood conditions Flood conditions Seine Trap Trap Trap Seine Tr Cyprinodontidae Fundulus olivaceus F. now Poeciliidae Gambusia affinis Aphredoderidae Aphredoderus sayanus Centrarchidae Elassoma zonatum Micropterus punctulatus 3.06 M. salmoides Ambloplites arthmmus Lepomis gulosus L. macrochirus L. punctatus L. megatons L. mwrolophus L. cyanellus L. margznatus L. auritus 1.02 L. human 3.06 Percidae Amrnocrypta beani Percma sclera P. nigrofasciaia Etheostoma swami E. zonate E. stigmaeum Total number Total species THE AMERICAN MIDLAND NATURALIST CC

7 eits Sitte Ross & BAKER: FISH RESPONSE TO FLOODS 7 Noturus leptacanthus, N. gyrinus and N. nocturnus all had the greatest Cf for night channel collections. Of these species, only N. gyrinus occurred more than once on the floodplain. Lepomis macrochirus, L. cyanellus, L. marginatus and Notropis texanus had peaks in C f for day floodplain collections and decreased greatly in Cf values for night floodplain collections. Elassoma zonatum and Etheostoma swami both had low Cf values in all collections; however, E. zonatum was not collected on the floodplain during the day. It is significant that in comparing channel and floodplain samples no species had its highest Cf value for the night floodplain collections, with the exception of one minor species. Aphredoderus sayanus, while common in s ine collections from the channel, was only collected by traps in night floodplain sets. Thus, fish activity decreased overall at night on the floodplainj Position on the floodplain, and the inferred movement pattern, also varied for species collected in traps. Five species, Lepomis macrochirus, L. cyanellus, L. marginatus, Notropis texanus and Noturus gyrinus, comprised most of the species collected by trapping from the floodplain (Table 1). Lin diurnal sets, Lepomis macrochirus, L. cyanellus and Notropis texanus increased in abundance with distance from the channel, suggesting a daytime movement toward the periphery of the floodplain (Fig. 4). At night, a reverse pattern occurred, as L. macrochirus and L. cyanellus were most abundant nearest the channel while N. texanus had a higher Cf in the midfloodplain area. Catches of all three species were much reduced at night) Lepomis marginatus had reduced Cf values at night, but both day and night collections had the greatest Cf at midfloodplain, suggesting that this species may have less diel movement. Most Noturus gyrinus taken on the floodplain moved only onto the margin near the channel, although several individuals were collected from the midfloodplain at night. Turbidity (JTU) increased as a function of flood level (r =.65; P <.05), including ES Channel, Day M Channel, Night F loodplam, Day 13 F loodplom, Night Notropis Noturus Noturus Noturus Lepomis LepOmis Lepomis Peron teranus leplaconthus gyrinus nocturnus macrochirus CyanelluS marginatus mgrolosoolo Fig. 3. Day and night changes in trap catch-per-effort from the channel and floodplain areas of Black Creek. The numbers above the histograms indicate total sample sizes

8 THE AMERICAN MIDLAND NATURALIST 109(1) both rising and falling flood stages. In separate analyses, however, rising and falling stages had similar JTU values (rising: 3i = 32.3 N = 3; receding; 35.4, s = 15.5, N = 10). The greatest turbidity occurred during peak flooding UTU = 65, N = 2). Daytime C F values of the darter Percina nigrofasciata were negatively correlated with turbidity (r =.65, P <.01) (Fig. 5), suggesting that this species becomes less active as visibility declines. No other numerically dominant diurnal fish had a significant correlation of e F with turbidity. Species commonly collected at night, such as Noturus leptacanthas, likewise, did not show a significant change in C I with turbidity. DISCUSSION The fringing floodplain of Black Creek, Miss., is exploited by a number of fishes during floods which generally occur from February through April. The species composition of the floodplain is only moderately different from the channel when seine and trap collections are treated collectively; however, fish species subject to trapping differ markedly between the two areas. hus, species using the lower portion of the water column (which are those potentially susceptible to traps) are different between channel and floodplain habitats. The comparison of the total known channel fauna with the total floodplain fauna is strongly influenced by abundant species characteristic of the upper water column, such as Fundulus olioaceus (Miller and Robison, 1973), Notropis roseipinnis and N. welaka (Baker and Ross, 1981) or species which move throughout the water column such as bluegill (Keast and Webb, 1966). As the floodplain becomes inundated, these species move outward with the rising water o 200 a Near channel f23 central LI Upper 20 Lepomis mocrochirus Lepomis cyanellus Lepomis marginatus Notropis tekanus Not tous gyrinus Fig. 4 Day and night changes in catch-per-effort at three floodplain locations. Histograms under the open rectangle are day collections; those under the shaded rectangle are night collections

9 1983 Ross & BAKER: FISH RESPONSE TO FLOODS 9 Considering species response to flooding, we recognize two groups of fishes: quiescent and exploitative. Quiescent species,. which restrict their activity during flooding, are exemplified in Black Creek by Percina nigrofasciata and Lepomis megalotis. Percina nigrofasciata was a common channel inhabitant, yet it was collected on the floodplain only once. Assuming that trap capture reflects activity, this species moves less as turbidity increases. Thus, during heavy flooding P. nigrofasciata apparently stays in the main channel and becomes inactive. Mathur (1973) considered P. nigrofasciata to be a sightfeeder, so its foraging efficiency may decline during flooding. Lepomis megalotis was also a common channel inhabitant (based on seining) but was not taken in our traps. Consequently, its movement in the main channel during floods could not be assessed. However, L. megalotis was never collected on the floodplain by seining, suggesting that it does not leave the stream channel to exploit resources made available by flooding. Guillory (1979) found that L. megalotis comprised less than 1% of the fishes captured by seine from the Mississippi River floodplain. Boyer and Vogele (1971) found L. megalotis in reservoirs only fed diurnally and its activity and feeding declined when turbidity was high, further supporting our categorization of L. megalotis as a flood-quiescent species. Flood-exploitative species included Lepomis macrochirus, L. cyanellus, L. marginatus, NotrOP - rs - kyrinus (as determined from trap collections) and Notropis welaka, N. roseipinnis, Fundulus olivaceus, F. notti and Gambusia affinis (as determined from seine collections). Lepomis macrochirus L. cyanellus and N. texanus were abundant in both trap and seine floodplain collections.dur preliminary stomach analyses of these species showed full guts, suggesting that active feeding occurred on the floodplain3 Numerous studies (e.g., Keast, 1965; Keast and Webb, 1966; Werner and Hall, 1976; Werner et al., 1977; Keast et at., 1978) have shown that bluegill and other sunfishes are generalists in habitat use, thus their rapid exploitation of a new resource is not surprising. Lepomis macrochirus and L. cyanellus primarily occupied the upper areas of the floodplain during the day. Werner et al. (1977) found that L. cyanellus in lakes occurred in shallower shore areas than did L. macrochirus, although juvenile bluegill used CATCH/(FORT r- 62 I - I i I - i i TURBIDITY (JTU) Fig. 5. Catch-per-effort of Percina nigrofasciaia as a function of turbidity (JTU)

10 10 THE AMERICAN MIDLAND NATURALIST 109(1) shallower water than adults. Both species occupy areas of vegetation. In Lake Opinicon, where L. cyanellus is absent, Keast (1978) found that bluegill predominated in vegetated shallower areas, although larger fish moved into more open areas offshore. Werner and Hall (1976) found that bluegill preferentially used weedy shoreline areas, but were displaced into more open water in the presence of green sunfish. Such habitat partitioning may not occur in ephemeral floodplain habitats. Werner a al. (1977) found that juvenile bluegill moved shoreward at night, while our data indicate a nocturnal movement toward the channel. Lepomis marginatus was much more common in the floodplain samples than in the stream channel. This small southeastern species is characteristic of sluggish streams and backwaters (Bauer, 1980), and did not show day-night changes in floodplain position. Notropis texanus is one of the most common fishes in the channel, where it is characteristically found near the bottom in own water (Baker and Ross, 1981). Guillory (1979) also found that N. texanus moved onto the Mississippi River floodplain. The only catfish taken on the inundated floodplain was Noturus gyrinus, but it was primarily collected from areas near the channel. Notropis welaka and N. roseipinnis were common in floodplain seine collections. In contrast to N. texanus, N. roseipinnis remained nearer to the edge of the main channel. Notropis welaka occurred in weedy areas of the floodplain. Its typical habitat in the Black Creek drainage is the sluggish portions of well-vegetated creeks (Baker and Ross, 1981). Both N. roseipinnis and N. welaka (to a lesser extent) are habitat specialists (Baker and Ross, 1981) contrasting with N. texanus, L. macrochirus and L. cyanellus. However, the floodplain provided the apparently preferred habitat of N. welaka. Notropis roseipinnis, a surface-oriented fish, also occurred along the channel margins at typical depths and current speeds. Notropis texanus was the only species characteristic of the lower portion of t e water column (Baker and Ross, 1981) which readily moved onto the floodplain. Three additional species, Fundulus olivaceus, F. notti and Gambusia affinis, all typically use slack water areas along stream margins (e.g., Pflieger, 1975). The inundated flordplain thus greatly increases the amount of suitable habitat for these three species. j Flood-exploitative species generally have breeding seasons that extend well beyond the time of spring flooding. For instance, L. macrochirus breeds from March to October in the southern part of its range and L. cyanellus reproduces from May into August (Carlander, 1977). Limited data on Notropis texanus also suggest that it has an extended breeding period (Smith, 1979). Heins and Davis (pers. comm., 1981) found that N. texanus reproduced from March to September in southeastern Mississippi. Funduha olivaceus and F. notti breed in May (Pflieger, 1975). Thus, greater nutrient availability provided by the inundated floodplain could increase the energy available for reproduction at a time when energy demands through gonadal development and rising water temperature would be increasing. Percina nigrofasciata, a flood-quiescent species, spawns during February to April in Louisiana (Suttkus and Ramsey, 1967), thus increased energy demands of gonadal development would occur prior to the usual time of flooding. However, P. nigrofasciala IS apparently variable in spawning time, as Mathur (1973) found it spawning in May and June in Alabama. Lepomis megalotis, another flood-quiescent species, begins spawning in May in Arkansas (Boyer and Vogele, 1971) and may continue through August (Carlander, 1977). Decreased activity during floods may reduce growth and reproduc - tive success in this fish. However, flood-quiescent fishes may also benefit indirectly from flooding by the transport of nutrients into the stream channel. "[he inundated floodplain also provides a nursery area for large numbers of juvenile fishes, especially centrarchids. This role ortleaplirris has also been suggested by Forbes (1925), Gunter (1957), Christenson and Smith (1965) and Guillory (1979). Welcomme (1979) concluded that year-class strength and growth rates are linked to variability in the intensity, duration and timing of floods in tropical river systems. i

11 1983 Ross & BAKER: FISH RESPONSE TO FLOODS 11 Temperate streams also fluctuate annually with respect to species composition and relative abundance (e.g., Whitaker, 1976; Starrett, 1951). At least part of this variability may be attributed to annual variability in flooding regimes, as suggested by Starrett (1951), Lange and Dmitriyeva (1973), Moyle and Li (1979) and others. A H YPOTHESIS Populations of flood-exploitative species may be favored during high discharge years because their use of seasonally abundant resources prior to spawning may increase the amount of energy available for reproduction. Population size of floodquiescent forms may decline, or benefit indirectly from increased nutrient transfer into the stream. For species which spawn prior to spring floods, any effect on the amount of energy available for reproduction would be delayed 1 year. To test the null hypotheses that population sizes of flood-exploitative and floodquiescent species are independent of spring flooding we used the 17 collections taken over 6 years from the main channel of the study site. Sampling methodology, as described by Baker and Ross (1981) and sampling effort were essentially constant during the study. Consequently, we used the number of fishes per collection as a measure of abundance. Only the most abundant flood-exploitative and flood-quiescent species, o e 175 Abundance C 150 I, a, :O" Spring Flow r- 20 re) I I - I 1 I I Fig. 6. Abundance residuals of the flood exploiter Notropis texanus, vs. average spring (January - May) flow (N )

12 12 THE AMERICAN MIDLAND NATURALIST 109(1) Notropis texanus (N = 1457) and Percina nigrofasciata ( N = 205), respegtively, are considered. The abundance of Notropis texanus declined during the study as a function of the number of collections (Y = X; F= 7.8; P <.05). Numbers of Percina ntgrofasciata did not decline as a function of collecting effort (F = 1.0; ns). The relationship of N. texanus abundance to spring flow (January-May) is thus presented as an adjusted mean: Y,,di V d,., where = (Y, i 7 1) (Sokal and Rohlf, 1969). The 3 years of high abundance of Notropis texanus occurred during the 3 years (1975, 1979, 1980) of high spring discharge ( > 35 m 3 /s), while the 3 years of low abundance corresponded to the 3 years ( ) of low spring discharge ( < 25 m 3 /s) (Fig. 6). The change in abundance between years is significantly correlated with the change in spring flow (r =.91; P <.05)4Thus, for N. texanus, the data falsify the null hypothesis and support the alternative hypothesis of a relationship between population success of flood exploiters and spring flooding The change in Percina nigrofasciata abundance vs. change in spring discharge of the previous year did not show a significant relation (r P >.05). It is important to note that the alternative hypothesis of a negative relationship of population size to flooding is not supported. The decline in actual abundance of Notropis texanus over the period of study is most parsimoniously ascribed to collecting effects. The impact of repeated collecting on minnow populations is varied. Larimore (1954) found that intensive scientific collecting for 3 years did not alter minnow population abundance in a small Illinois stream (Si width = 6.7 m); however, Markus (1934) related declines of minnow populations in Illinois to activities of bait collectors. Effects of repeated collecting on the fish populations of Black Creek will be further addressed in a subsequent paper. - Our study further demonstrates the importance of fringing floodplains to stream fishes. The fish assemblage in Black Creek may be controlled in part through structural habitat suitability (cf., Baker and Ross, 1981) and in part through stochastic events such as the intensity of spring flooding. It is also apparent that each species responds differently to these factors. Acknowledgments. We are grateful to Kathleen Clark and Timothy Modde for their help in the planning and fieldwork of this study. We also thank David Ruple, Steven Byers and Chester Rakocinski for helping with fieldwork. Collection of baseline data on Black Creek was supported by grants from the South Mississippi Electric Power Association (SMEPA). We thank William Matthews for his extremely helpful suggestions on the manuscript and Yvonne Ross for her editorial comments. We are grateful to Loren G. Hill for making the facilities of the University of Oklahoma Biological Station and Zoology Department available to us during the completion of this study. LITERATURE CITED BAKER, J. A. AND S. T. Ross Spatial and temporal resource utilization by southeastern cyprinids. Copeia, 1981: BAUER, B. H Lepomis marginatus (Holbrook), dollar sunfish, p /n: D. S. Lee, C. R. Gilbert, C. H. Hocutt, R. E. Jenkins, D. E. McAllister, and J. R. Stauffer. Atlas of North American freshwater fishes. N. C. State Mus. Nat. Hist Raleigh. BENNETT', G. W Aquatic biology, p /n: H. B. Mills, G. C. Decker, H. H. Ross, J. C. Carter, B. B. East, G. W. Bennett, T. G. Scott, J. S. Ayars and R. R. Warrick. A century of biological research. III. Nat. Hirt, Sum. Bull., 27: BOYER, R. L. AND L. E. VOGELE Longear sunfish behavior in two Ozark reservoirs, p In: G. E. Hall (ed.). Reservoir fisheries and limnology. Am. Fish. Soc., Spec. Publ. No. 8. BROWER.J. E. AND j. H. ZAR Field and laboratory methods for general ecology. Wm. C. Brown Co., Dubuque. 194 p. CARLANDER, K. D Handbook of freshwater fishery biology, Vol. I. Iowa State University Press, Ames. 752 p Handbook of freshwater fishery biology, Vol. II. Iowa State University Press, Ames. 431 p.

13 1983 Ross & BAKER: FISH RESPONSE TO FLOODS 13. CHRISTENSON, L. M. AND L. L. Storrit Characteristics of fish populations in upper Mississippi River backwater areas. U.S. Fish Wild!. Sew. Circ p. CROSS, R. D., R. W. W ALES AND C. T. TRAYLOR Atlas of Mississippi. University Press of Mississippi, Jackson. 187 p. FoRBES, S. A The lake as a microcosm. /it Nat. Hist. Surv. Bull., 15: GREENFIELD, D. W. S. T. Ross AND G. D. DEGKEKT Some aspects of the life history of the Santa Ana sucker, Catostomus (Pantosteus) santaanae (Snyder). Calif. Fish Game, 56: GUILLORY, V Utilization of an inundated floodplain by Mississippi River fishes. Fla. Sci., 42: GUNTER, G Wildlife and flood control in the Mississippi Valley. Trans. N. Am. Wild!. Nat. Resour. Conf, 22: HANSON, D. L. AND 'F. F. WATERS Recovery of standing crop and production rate of a brook trout population in a flood-damaged stream. Trans. Am. Fish. Soc., 103: HARREI.L, H. L Response of the Devil's River (Texas) fish community to flooding. Copeia, 1978: HooPEs, R. L Flooding as the result of Hurricane Agnes, and its effect on a native brook trout population in an infertile headwater stream in central Pennsylvania. Trans. Am. Fish. Soc., 104: HORN, H. S Measurement of "overlap" in comparative studies. Am. Nat., 100: Jotini, K. R The effect of torrential rains on the reproductive cycle of Rhinichthys scuba in the Chiricahua Mountains, Arizona. Copeia, 1963: Survival of fish in intermittent streams of the Chiricahua Mountains, Arizona. Ecology, 45: KEAST, A Resource subdivision amongst cohabiting fish species in a bay, Lake Opinicon, Ontario. Great Lakes Res. Div. Univ. Mich. Pub!. 13: Trophic and spatial interrelationships in the fish species of an Ontario temperate lake. Environ. Biol. Fishes, 3:7-31.,J HARKER AND D. TURNBULL Nearshore fish habitat utilization and species asso- ciations in Lake Opinicon (Ontario, Canada). Ibid., 3: AND I). WEBB Mouth and body form relative to feeding ecology in the fish fauna of a small lake, Lake Opinicon, Ontario. J. Fish. Res. Board Can., 23: LANGE, N. 0. AND YE. N. DMITRIYEVA Some characteristics of the effect of similar environmental factors (maxima of the spring flood and the springtime temperature regime) on juvenile fishes of different ecological groups. J. Ichthyol. (Engl. Trans!. Vopr. Ikhtiol.), 13: LAKimoKE, R. W Minnow productivity in a small Illinois stream. Trans. Am. Fish. Soc., 84: LEoPoi.o, L. B., M. G. WOLMAN AND" P. MILLER Fluvial processes in geomorphology. Freeman, San Francisco. 522 p. MARKUS, H. C The fate of our forage fish. Trans. Am. Fish. Soc., 64: Meat-RIK, D Some aspects of life history of the blackbanded darter, Percina nigrofasciata (Agassiz), in Halawakee Creek, Alabama. Am. Mid!. Nat., 89: KlIEEEK, R. J. AND H. W. ROBISON The fishes of Oklahoma. Oklahoma State Univ. Press: Stillwater. 246 p. MOVIE, P. B. AND H. W. Li Community ecology and predator-prey relations in warmwater streams, p /n: H. Clepper (ed.). Predator-prey systems in fisheries management. Sport Fishing Inst., Wash., D. C. PALOUMPIS, A. A Responses of some minnows to flood and drought conditions in an intermittent stream. Iowa State]. Sci., 32: PFLIEGER, W. L The fishes of Missouri. Missouri Dep. Conserv., Columbia, Mo. 343 p. SEEGRIST, D. W. AND R. GARD Effects of floods on trout in Sagehen Creek, California. Trans. Am. Fish. Soc., 101: SMITH, P. W The fishes of Illinois. Univ. Illinois Press, Urbana. 314 p. SOKAL, R. R. AND F. J. ROHLF Biometry. W. H. Freeman and Co., San Francisco. 776 p. STARRETT, W. C Some factors affecting the abundance of minnows in the Des Moines River, Iowa. Ecology, 32: SurrKus, R. D. ANDI RAmsEv &mina aurolineata; a new percid from the Alabama River System and a discussion of ecology, distribution, and hybridization of darters of the subgenus Hadropterus. Tulane Stud. Zoo!., 13:

14 .14 THE AMERICAN MIDLAND NATURALIST 109(1) Ummo SrA ES GEOLOGICAL SURVEY, Water resources data for Mississippi. U.S.G.S. Water Data Rep. MS-39- I -MS VioscA, P Flood control in the Mississippi Valley and its relation to Louisiana fisheries. Trans Am. Fish. Soc., 57: WELcommE, R. L Fisheries ecology of floodplain rivers. Longman, New York. 317 p. WERNER, E. E. AND D. J. HALL Niche shifts in sunfishes: experimental evidence and significance. Science, 191: , D. R. LAUGHLIN, D. J. WAGNER, L. A. WILSMANN AND F. C. FUNK Habitat partitioning in a freshwater fish comtnunity.f. Fish. Res. Board Can., 34: WHITAKER, j. 0., JR Fish community changes at one Vigo County, Indiana, locality over a twelve year period. Proc. Indiana Acad. Sci., 85: WICKLIFE, E. L Some effects of drouths and floods on streamfish. Ohio Dep. Agric. Bull. No p. SUBMITTED 5 OCTOBER 1981 ACCEPTED 8 FEBRUARY 1982