Transactions of the American Fisheries Society 126:895-907, 1997 © Copyright by ihe American Fisheries Society 1997

Factors Influencing Stream Fish Recovery Following a Large-Scale Disturbance WILLIAM E. ENSIGN' and KEVIN N. LEFTwiCH2 Department Fisheriesof Wildlifeand Sciences, Virginia Tech Blackshitrg, Virginia 24061-0321, USA PAUL L. ANGERMEIER U.S. Geological Survey, Biological Resources Division Virginia Cooperative Fish and Wildlife Research Unit,* Virginia Tech, Blacksburg, Virginia 24061-0321.USA . ANDREC W DOLLOFF U.S. Forest Sen'ice, Southern Research Station, Virginia Tech Blacksburg, Virginia 24061-0321. USA

Abstract.—We examined fish distribution and abundance in erosional habitat units in South Fork Roanoke River, Virginia, following a fish kill by using a reachwide sampling approach for 3 species and a representative-reach sampling approach for 10 species. Qualitative (presence-absence) and quantitative (relative abundance) estimate f distributioso abundancd nan e provided consistent mea- sure f fiso s h specie 3 reachwide recover f th o speciet 0 2 a s1 r f yfo o e srepre 8 e scal ath d t an e- sentative-reach scale. Combining results across scales and estimator types showed that distributions and abundance f 1o 1 5 specie reace f so th hn i s affecte kile th l y werdb e simila thoso rt e observed in unaffected upstrea downstread man m reaches 8-11 months following the perturbation. Differ- ence distribution i s abundancd an n e betwee e affectenth d reac unaffected han d reaches indicate f tha1o 1 t full4 tspecie no yd recovereha s d durin same gth e time period; results were equivocal fo othe2 r r species attribute W . e difference recovern si y rates between thes groupo tw e difo t s - ferences in parental investment in offspring. Species exhibiting rapid recovery either engage in extensive spawning site preparatio r guarno e spawnindth g site followin g depositioeg g d nan fertilization; species that had not recovered in the year following the kill show limited spawning site preparation and do not guard the spawning site.

Stream fisexposee har boto dt h - naturatemplatan d an l e determinin range gth liff eo e history traits thropogenic disturbances thaalten ca t r population founa strea n i dm fish assemblage (Res t ale h . distribution and abundance. We need to understand 1988). At a given site, local factors such as dis- the factors that influence population recovery fol- tance to source populations of potential colonists lowing disturbance orden si effectivelo rt y manag occurrencd an e f barriero e movemeno t s e imar t- stream fish resources (Cairns et al. 1971; Hughes portant (Cairns et al. 1971; Gore and Milner 1990; . 1990eal t ; Detenbec . 1992)al t e k . Factor - de Detenbecs . 1992)al t ke . Finally, life history traits termining recovery rates can be viewed in a hi- defining potential rates of population increase erarchical fashion (Detenbeck et al. 1992). Re- (e.g., Winemiller and Rose 1992) and vagility of gional variations in climate, geomorphology, and individuals should determine differential recovery hydrologic regime provide the large-scale habitat rates in a given assemblage. Most studie fisf so h population recovery follow- ———— ing large-scale natural or anthropogenic distur- 1 Present address: Department of Biological and Phys- bance come from second fourth-ordeo t - r streams ical Sciences, Kennesaw State University, 1000 Chastain that have fish assemblages thae well-adaptear t d Road, Kennesaw, Georgia 30144, USA. to periodic disturbance (Niemi et al. 1990; Schlos- 2 Present address: U.S. Forest Service, Center for Ser 1990; Detenbeck et al. 1992). Response vari- Aquatic Technology Transfer, Southern Research Sta- ables m frequently limited to either qualitative lion. Virginia Tech, Blacksburg, Virginia 24061-0321, (presence_absence) or ^quantitative (relative Unie jointls 3Th i t y sponsore Biologicae th y db - abundanceRe l ) data fro ma limite d numbe f "repo r - sources Division of the U.S. Geological Survey, the Vir- resentative" sites (Niemi et al. 1990). Data on pop- ginia Departmen Gamf t o Inlan d ean d Fisheries, Virginia ulation densit d spatiayan l distribution durind gan Tech, and the Wildlife Management Institute. after recovery from a variety of regions and stream 895 896 ENSIG. AL T NE

size needee sar develoo dt pcomprehensivea , pre- ginia. Predominant land use in the watershed is dictive theory of fish population recovery follow- agricultural, with the majority of the area in pas- in ga disturbance . Furthermore, additional infor- ture or woodland. The riparian zone is largely veg- matioutilite th sensitivitd n yan no f qualitativyo e etated, with willows Salix spp., American hack- and quantitative response variables across spatial berry Celtis occidentalis, and sycamore Platanus sampling scales (i.e., from both representative- occidentalis dominane th s a t woody riparian spe- reacd reacan h h wide approaches; Hankid an n cies. Total watershed area above a gauging station Reeves 1988; Dolloff et al. 1993) is needed to in the middle of the study reach (Figure 1) is 285 facilitate design and implementation of effective km2; mean daily flow for the period of record is recovery monitoring programs. Although manip- 3.14 nvVs, and stream gradient is 1.7 m/km. Hy- ulative studie providn ca s e insight into recoloni- drologic records indicate thae studth t y reach zation following small-scale defaunations (Meffe maintained continuou perioe s th flo r f recdwo fo - and Sheldon 1990; Peterse d Baylean n y 1993), ord (more than 40 years). Average stream width dat large-scalr afo e studie usualle sar y obtainey db is 16.7 m; average pool depth is 52 cm; and max- treating anthropogenic disturbance s experia s - imum pool depth is usually less than 1.5 m, al- ments (Spark . 1990)al t se . though some pools exceed 3 m. Although there are On 15 October 1991, a dairy farm in Riner, Vir- perennial streams entering South Fork Roanoke ginia, accidentally released 100,000 gallons of liq- upstrea downstread man m fro affectee mth d reach, uid manure into Elliott Creek. In all, 22 km of the only tributaries entering the affected reach are stream were affected, 13 km of Elliott Creek and smal intermittentd an l . 9 km of South Fork Roanoke River downstream For the reachwide component of the study, we of its confluence with Elliott Creek. The Virginia studR divideSF y e areth d a into three separate Water Control Board estimated that over 190,000 reaches, an upstream (US) control reach, a down- fish were killed. Qualitative streamside observa- stream (DS) control kila reac d l (KLhan ) reach. tion immediateld s 3 ove e rth y followin spile gth l The US reach included a 3-km stretch of SFR be- believo t lea s du e thaichthyofaune th t s vir-wa a ginning near the mouth of Elliott Creek and ex- tually eliminate- af e th df o fro uppee m mth k 6 r tending upstream reacS D d he an begaTh .m k n9 fected reac Soutn ho h Fork Roanoke e terth - n I . downstreaendem k 3 1 d moute th f mf Ellioto ho t minolog f Bendey o . (1984 al t Gord e rd an ) ean Creek, and the KL reach included the 6 km of SFR Milner (1990) manure th , e classifieeb spiln ca l d immediately downstrea e moutth f f mEllioto ho t level-a s a 2 pulse disturbance, which indicates that Creek (Figure 1). Fish were collected from seven upstrea downstread man m source colonistf so - sex sites for the representative-reach portion of the isted followin spile thad causae gth an th lt l agent study downstreamo tw , upstreamo tw , thred an , e t altedidno r physical habitat availabl potentiao et l withi affectee nth d reach (Figur. 1) e recolonizers. Although the spill is regrettable, it We determined reachwide distributio abund nan - d providdi n opportunita e o refint y r underou e - danc f threeo e species, Roanoke standin factore th f go s that influence fish recolon- rex, Roanoke darte . roanoka,P r blacd an k jump- ization following perturbation. rock Scartomyzon (=Moxostoma) cervinus. Distri- We present the results of a 2-year study that butio abundancd nan species—whit0 e 1 dat r afo e assessed fish recolonizatio affectee th n ni d reach. shiner Luxilus albeolus, crescent shiner L. cerasi- The four major objectives of the study were (1) to nus, bluehead chub Nocomis leptocephalus, central determin e distributioth e d abundancnan - se f o e stoneroller Campostoma anomalum, torrent sucker lected riffle-dwelling fish species in the study Thobumia (—Moxoslonia) rhothoeca, black jump- reach during summer 199 asses1993d o t 2an ) (2 ,s rock, margined mad torn Noturus insignis, fan tail the utilit f reachwido y representative-reacd an e h darter Etheostoma flabellare, river weed darter £. approaches for determining recovery, (3) to assess podostemone, and Roanoke darter—were obtained e utilitth f qualitativo y e (presence-absenced an ) from the seven representative-reach sites. Juve- quantitative (relative abundance) measures for de- niles and adults of all 11 species are commonly termining asseso t recovery ) role f (4 th s eo d an , difference lifn i se history characteristic detern si - found in erosional, riffle-run habitat from the time mining recovery rates. they spaw latn ni e spring until water temperatures dro earln pi y winter, when they move into deep, Study Area and Study Species slow-moving pools (Matthews 1990; Jenkind an s South Fork Roanoke (SFR) is a fifth-order Burkhead 1994; Ensign 1995). They are all either streae Valleth Ridgd mn i yan e Provinc f Vireo - benthi water co r column insectivores- , ex wit e hth FISH RECOVERY AFTER DISTURBANCE 897

Roanoke River

Elliott Creek FIGURE I.—The South Fork Roanoke River study area. Representative-reach study site e indicatear se th y db solid bars bisecting the river, upstream (US) and downstream (DS) reaches are indicated by solid gray, and the kill (KL) reach is indicated by cross-hatching. The upstream and downstream limits of the effect of the manure spill area indicated by stars on Elliott Creek and South Fork Roanoke River, respectively.

ception of the algivorous central stoneroller (Jen- reaches for all 11 study species, thereby minimiz- kins and Burkhead 1994). Although similar in hab- ing the potential for differences among reaches itat preferenc d trophian e c classification e 11th , related to seasonal movements for both reachwide study species diffe mann i r y life history charac- and representative-reach sampling. teristics, most notably parental investmen offn i t - In each of the units sampled, two snorkelers spring (Jenkin Burkhead san d 1994). entered the water at the downstream end of the unimoved an t d upstrea straigha mn i t line. Snor- Methods kelers attempted to maintain positions approxi- Data collection.—We used underwater obser- mately one-third and two-thirds of the distance vation to determine reachwide distribution and from the left ascending streambank. Observers abundance of Roanoke logperch, Roanoke darter, scanned the stream bottom directly in front and to and black jumprock. Sampling was conducted in both side f theiso r lin f traveeo kepd an ltalla t y erosional (riffle-rund ) an habita , DS , t unitUS n si l adulal f to Roanok- e l ju darteradul al d d an t san reacheL K s during late May, June Juld an ,y 1992 venile Roanoke logperch and black jumprocks ob- and June and July 1993. Erosional units were vi- served. Young-of-year wer t includeno ee th n i d sually identifie s areaa d f shalloo s moderato wt e counts. Following completio observatioe th f no n depth (typically les ) wits cm htha 0 moderatn5 e pass, the length of the sampled unit was measured. higo t h current velocity (typically greater tha0 n2 Because water clarit influencn yca numbee eth f ro cm/s). Although we were unable to sample all units fish seen, turbidit measures ywa beginnine th t da g in each reach during both years, units that were f eac wito y an hd da Hacha den h mode 0 tur94 -l sampled during both years were evenly distributed bidimeter. across the three reaches. During both years, qual- We estimate densite three dth th f eyo specie n si itative underwater observatio f fisno h behavio- rin individual habitat units using a modified line tran- dicated that spawning activity had ceased in all sect approach (Emlen 1971; Ensign et al. 1995). 898 ENSIG. AL T NE

Species-specific densities in a given unit were es- the US and DS reaches, we concluded that there timate dividiny db e numbegth f fiso r h observed was evidence for kill effects in 1992. Because produce b lengte ylinth e th th e f f snorkeledho to , there were three comparison eacr sfo h speciese w , the boundary width (an estimate of the maximum use dBonferrona i correctio maintaio nt spee nth - perpendicular distanc t whica e a specieh- ob s i s cies-specific comparison wise erro= r P rat t a e served), and a correction factor accounting for the 0.05. This lowere minimur dou m significance level declining probabilit f sightinyo individuan ga l fish 0.01= toP 7 (0.05/3 = 0.017). functioa s a f increasino n g distanc- e ob fro e mth We assessed quantitative changes in species' server's line of travel. A full description of the abundance using a Kruskal-Wallis test with each technique applications it , reliabilite th d e th an , f yo combination of year and reach as a unique group. estimates obtained is given elsewhere (Ensign et Our response variable in the reachwide data set al. 1995). was fish density (number/ha), with each sampled We obtained representative-reach data by con- erosional unit serving as a single observation. For ducting electrofishing surveys during Augusd an t the representative-reach data set we used number September 1992 and 1993 at the seven sites in the of individuals capture quadrar responsde pe th s a t e study area (Figure 1). We used an AC backpack variable, with each sampled quadrat servinn a s ga electrofishin ga 0.6-cm-mes unid an t h seine that observation. Because we lacked data on fish abun- was 4.5 m long and 1.5 m deep and had a 1.5-m dance in the study area before the kill occurred, by 1.5- y 1.5-m b attachedg mba e seins Th . wa e our initial null hypothesis was that there should held downstream of the area to be sampled and significano an e b t difference among groups. Abun- rectangular quadra longwidem m - 0 4 ( im 1 )t, dant evidence exists for longitudinal gradients in mediately upstream of the seine was thoroughly stream fish abundance gived spatiaan ,e nth l extent electrofished. Following completion of electrofish- samplingr ofou , difference abundancn si e between ingl e fissein s al liftedth ,h d wa eretaine an , n di the US and DS reaches could confound inferences the net were identified and counted. The electro- related to recovery patterns in the KL reach. There- fished quadrat was searched, and fish observed on e Kruskal-Walliforeth f i , s s significanteswa t P ( t the stream bottom were retrieved and included in < 0.05), we conducted a series of pairwise com- the sample. parisons using Wilcoxon rank-sum tests. This pro- At each site, sampling proceeded upstream cess allowed us to refine our understanding of dif- along a series of transects placed perpendicular to ferences in abundance between the two unaffected streamflow at 15-m intervals. Quadrat locations reaches acros sdetermin o t year d san impore eth - were determined systematically. The adjoining tance of differences in KL reach abundance among edge quadratf so singla n so e transect wer t leasea t reache r acrosso s years e firsTh .t four tests com- apartm 2 , wit outside hth e edg t leasefroa m m2 t pared abundanc n unaffectei e d reaches across the adjacent bank. The number of quadrats on a years (US92 versus US93 and DS92 versus DS93; given transect was a function of stream width and year is indicated by the last two digits) and within criteria previously mentioned. Spacing and loca- years (DS92 versus US92 and DS93 versus US93). tion of quadrats and techniques employed during finae Th l five tests compare reacL dK h abundance settin e seinliftind th gan f eo gwer e designeo dt across years (KL92 versus KL93) and KL reach minimize disturbance of areas to be shocked. reacS D abundanchd abundancan S U o et e within Statistical analysis.—We assessed qualitative years (KL92 versus DS92, KL92 versus US92, change fisn si h abundanc compariny eb g presence KL93 versus DS93 and KL93 versus US93). Be- d absencan f fis o en individua i h l sampling units cause there were nine pairwise comparisonr fo s within each reach betwee nreache yearsth r - Fo . each species usee w , dBonferrona i correctioo nt wide component of the study, erosional units snor- maintai r comparisonwisou n e erro= r P rat t a e kele botn di h years serveindividuae th s da - ob l 0.05. This lowered our minimum significance level servations, and we used Fisher's exact test to de- to P = 0.006 (0.05/9 = 0.006). termine differences within reaches between years. For the representative-reach portion of the study, Results individual quadrats e servesamplinth s a d g unit and difference reachen i s s between years wer- ede Reachwide Comparisons termined with a chi-square test. If changes in the There were 56 erosional habitat units in the proportio f occupieno d sampling e KunitLth n i s stud yf those o area snorkeled e w ,an , botn i h6 d3 reach differed significantly from that observen di reachyearsS L D K d e e an ,,th th 1n n 51i i FISH RECOVERY AFTER DISTURBANCE 899

Roanoke darter Roanoke logperch Black Jumproc,.f- ----k- 4000 n 175- 700 -i -• ^ 3200- 140 - 560 - CO T <> 0 420- t g, 2400 - 105 - T o

1601 0- 70 - o 280 -

S ,i 800- * 35 - * i. "•• } ,M* i J 1 0 - —— 0 - ——— • ————0 -* -

1.0 -i 1.0 -i 1.0 -,

a 0.8- 0.8 - 0.8 -

H 0.6- 0.6 - - 6 0. •

0.4 - ||°'4" °-0 0. 2- i::: 0.2 - i n n 9293 9293 9293 9293 9293 9293 9293 9293 9293 S U L K S D S U L K S D S U L K DS FIGURE 2.—Mean densities (upper graphs; number/ha) and proportion of habitat units occupied (lower graphs) for Roanoke darter, Roanoke logperch, and black jumprock based on the reachwide sampling data. Error bars represen confidenc% 95 t e intervals (CI) aroun poine dth t r estimategraphs uppee ba th e th d .r r san C fo I

reachS U e 1992n I .th n i , Roanok0 1 e darter were observed in all units in the US and DS reaches TABLE I.—Significance level f pairwiso s e Wilcoxon and 13 of 15 units in the KL reach. In 1993, they rank-sum test r differencesfo densitn i s y between reaches were observe l l reacheunital al n n i sdi s (Figure y yeab r combination d Fisher'an s s exact r tesdifferfo t - . Roanok2) e logperch were foun e unit6 th n di n si ence frequencn si f

reaches from % the reachwide data setr Roanoksfo e darter. reacDS 1992hin the 199in ; 3 they were foundin Roanoke logperch, and black jumprock reachesS D . d Abbreviationan , L K , US s e founit0 th 1 r n d si , 1 2 1an reach by year comparisons are as follows: DS = down- stream reach, US = upstream reach, KL = kill reach. Year respectively (Figure 2). Black jumprock were is represented by its two final digits. An asterisk (*) in- found in all 10 US reach units, 11 KL reach units, dicates significant difference, given Bonferroni correctio reacS D , d 0 h121 n10 an unit, d n i 199n an i s d 2an for multiple comparison e Wilcoxo 0.00< th r P ( s6fo n 11 units in the US, KL and DS reaches, respec- tests; P < 0.017 for Fisher's exact tests). tively n 199i , 3 e (FigurnumbeTh . f unit2) eo r s Reach-by-year Roanoke Roanoke Black reacL occupieK he th differe n di d between years comparison daner logperch jumprock only for Roanoke logperch (P = 0.003; Table 1). Wilcoxon pairwise comparisons We observed differences in density between at DS92 versus US92 0.460 0.025 0.526 least one reach by year combination for all three DS93 versus US93 O.I 30 <0.(K)l* P l ; Tabl Fig, 1 e - Fisher's exact test contrastn I . ur e2) reac L K , h densities were sig- DS92 versus DS93 1. 000 0.476 1.000 nificantly reacS loweD hd rdensitiean thaS U n s KL92 versus KL93 0.483 0.003* 1.000 in 1992 d 199 reacL an , 2K h densities were sig- US92 versus US93 1. 000 O.I 70 I.(KX) nificantly lower than 1993 KL reach densities (all 900 ENSIGN ET AL.

TABLE 2.—Significance levels of pairwise Wilcoxon rank-sum tests for differences in quadrat abundance between reaches by year combinations and chi-square test for differences in frequency of occupied quadrats between years within reaches from the respresentative-reach data sets for 10 of the species studied. Data for Roanok? logperch were not analyzed because of the low abundance of this species. Abbreviations for reach-by-year comparisons are as follows: DS = downstream reach, US = upstream reach, KL = kill reach. Year is represented by the last two digits. An asterisk (*) indicates significant difference, given Bonferroni correction for multiple comparisons (P < 0.006 for Wilcoxon tests; P < 0.017 for chi-square tests).

Reach-by-year White Crescent Bluehead Central Torrent Black Margined comparison shiner shiner chub stoneroller sucker jumprock madtom Wilcoxon pairwise comparisons DS92 versus US92 0.249 <0.(X)1* 0.003* 0.012

0.001P< ; Tabl , Figure1 . Roanoke2) e logperch chango n ther s occupien ei wa e d quadrate th n i s densities within the two reaches unaffected by the DS reach (P > 0.017; Table 2). spill did not differ between the 2 years of the study There were significant differences in abundance 0.006(P> ; Tabl ereac L 1K , ht Figur denbu , -e2) between at least one reach by year combination sities increased significantly from 199 1992o t P 3( for all 10 species (Kruskal-Wallis test; all P < 0.001< ; Tabl onle , Figur1 eTh y . change2) n ei 0.05) patterne .Th observee sw numben di f fisro h black jumprock abundance was a significant in- per quadrat between years and among reaches pro- reacS D creashe th fro n ei m 199 o 1992< t P 3( vides no evidence of postkill effects in 1992 for 0.001; Table 1, Figure 2). white shiner, fantail darter, and riverweed darter. For all three species, there were no significant dif- Representative-Reach Comparisons ferences in abundance between years for any of During 1992 samplee w , S quadrat9 d3 D e th n si the three sampled reache s0.006 > (al P l ; Table reacUS h the in reach32 KL and , the reach in 58 , , Figur2 . White4) e shiner abundanc highes ewa r (total quadrats)9 12 , 1993n .I obtainee ,w d samples in the KL reach than in the US reach in both 1992 L K e th fro reach S n quadrat9 i D m3 9 e 5 ,th n i s (P = 0.005) and 1993 (P = 0.002), but year-to- reacS U he (totalth n quadrats)3 i 5 13 ,reac3 d han . year consistency in this pattern and lack of dif- There was no evidence for significant differ- ferences between DS and KL reach abundances in ences in the number of occupied quadrats within reaches between year r whitfo s e shiner, crescent both year 0.006> P s( ) (Tabl Figur; e2 suggest) e4 s shiner, bluehead chub, fantail darter riverweer o , d this may be a natural longitudinal abundance gra- darter (all P > 0.017; Table 2, Figure 3). The num- dient similaA . r patterseee botb r nn fo hnca fantail ber of quadrats occupied in the KL reach increased darter and riverweed darter, as there are no sig- significantly from 1992 to 1993 for central stone- nificant differences within reaches between years roller (P = 0.005), torrent sucker (P = 0.009), 0.006(P> ; Tabl Difference. e2) s between reaches margined madtom (P = 0.005), and Roanoke dart- within years are consistent with a longitudinal pat- 0.001< P ( )r e (Tabl ; Figure2 , althouge3) h there tern in which highest abundance of both species wa chango sn occupien ei r o d S quadratD e th n si is found in the US reach (Figure 4). US reach for any of these species (P > 0.017; Table We found strong evidence of manure spill ef- numbee Th . quadratf 2) ro s containing black jump- fects on KL reach populations of central stone- rock in both the KL and US reaches increased roller, torrent sucker, black jumprock Road an , - significantly from 199 1990.00o 2P t < d P 3( 1 an noke darter. While there were no significant dif- 0.008= , respectively; Tabl , Figur2 e , while3) e ference numbee th n i sf centra o r l stoneroller, tor- FISH RECOVERY AFTER DISTURBANCE 901

TABLE 2.—Extended. abundancS U t bu s highe , ewa 2) r tha abunS nD - danc botn ei h 1990.00< crescenP r 2( 1fo t shiner, 0.00= P 3 for bluehead chub 1990.00d < )an P 3 ( 1 for both) (Tabl ; Figure2 . Althouge4) reacL hK h abundances significantly differed from eitheS U r or DS reach abundances in at least 1 year (Table 2), a parsimonious interpretation would suggest Reach-by-year Fan tail River weed Roanoke comparison darter darter darter that these differenceyear-to-yeao t e du e ar s r vari- ation in abundance in the KL reach. Margined Wilcoxon pair wise comparisons madtom KL reach abundance increased from 1992 DS92 versus US92 <0.001* <().(X)I* 0.951 DS93 versus US93

White shiner Black jumprock

92 93 92 93 92 93 92 93 92 93 92 93 S U L K S D DS KL US FIGURE 3.—Proportion of quadrats occupied for 10 of the 11 study species based on representative-reach sampling data. (Data for Roanoke logperch were not analyzed because of low abundance.) Error bars represent the upper 95% confidenc r graphe ba interva e .th r fo l

Discussion spatial scales, data types studd an , y species (sum- Methodological Comparisons marized in Table 3) can provide managers with informatio desige th r futurf nfo o e recovery mon- Our objectives were formulate addreso dt s three itoring programs. linked methodological questions qualitao D ) (1 .- resulte Th s obtained fro reachwide mth e datt ase tive and quantitative indices of fish abundance and showed that qualitative and quantitative measures distribution provide equivalent information at a of abundance coincid r Roanokefo e logpercd han reachwide sampling scale? (2) Do qualitative and black jumprock but conflict for Roanoke darter quantitative measure f fisso h abundanc disd ean - (Tabl . Lace3) f agreemenko r Roanokfo t e darter tribution provide equivalent information with ma attributee yb factorso tw o dt , vagilit abund yan - small-spatial scale sampling within representative dance in unaffected reaches. Although specific reachese therAr e) difference(3 ? e inforth n -i s studies suggest that individual Roanoke darters mation obtained from reachwid representad ean - may have high site fidelity (Lee and Ashton 1981), tive-reach samples? Comparisons among different anecdotal evidence, particularl rapie yth d expan- FISH RECOVERY AFTER DISTURBANCE 903

9>0 -, White shiner 90 -, Black jumprock 7.2 - 7^ - 5.4 - 0 5.4- 3.6 - 3.6 - 1.8 - 1.8 - A. "•* „ J ,i 0. 0——————————————- 25.0 -i Crescent shiner 90 Margined madtom 20.0 - 7.2 - 15.0 - 5.4 - 10.0 - 4 3.6 - 5.0 - »_ T 5!'!x' : T!T ? 0 ———————————————0. •g T "O 250-1 Blueheaj chub 25.0 -i Fantail darter § 20.0 - *. 15.0 - 15.0 - I T 0) 1 0. 10.0 - 10.0 - | T I fe 5.0- •5- j 5.0 - J li E o.o ———— 0.0 - —— Z 25.0 -i Central stoneroller 90 -, Riverweed darter 20.0 - 7.2 - T 15.0 - - 4 5. o 10.0 - 3.6 - 5.0 - 1.8 - ,i ,3E I on - _,il———— nn -

< > T ^ >

FIGURE 4.—Mean abundance (numbe f fish/quadratro e II th studr 1f 0o fo ) y species base thn do e representative- reach sampling data. (Dat Roanokr afo e logperch wer analyzet eno d becaus abundance.w lo f eo ) Error bars represent confidenc% 95 e intervals aroun poine dth t estimates.

sion of the species in the James River basin, in- nally, Roanoke logperch are typically found in low dicates that at least some Roanoke darters are high- abundance even under normal conditions, so it is ly mobile (Jenkin d Burkheaan s d 1994). Given not surprising that presence-absence and abun- mobile and sedentary portions of a population with dance measures would coincide during the early moderate abundance, ther g s potentiai ela a r fo l stages of recovery. Therefore, either approach between occupatio f habitano t unit colonizery sb s would serv reasonabla s ea e measur f recovereo y and reestablishmen f originao t l population abun- for species with high mobility abundancew lo , r o , dance through reproductive output. Accordingly, a combination of both characteristics. the qualitative measure is a poor indicator of pop- At the representative-reach scale, there was ulation recovery. good agreement between quantitativ qualid an e - In contras Roanoko t e darters, black jumprocks tative measures for all species, except margined occu relativeln i r abundancw ylo e highl ar d yean madto blacd man k jumprock (Tabl . Althouge3) h mobile mosar s t e(a catostomids) . Rapid random fin n reasonablo ca dn e w e explanatio lace th kr nfo diffusio f boto n h adult juveniled an s s fro- mup of agreemen e measure th e margine th n i tr fo s d strea d downstreaman m population s sufficieni s t madtom, there is a logical reason for the differ- reestabliso t speciee hth suitabln si e habitat units ences seen for the black jumprock. The quantita- and return abundanc preperturbatioo et n levels- .Fi tive measure indicate o dchang n thers n i ewa e 904 ENSIGN ET AL.

TABLE 3.—Summary of evidence for species recovery following the South Fork fish kill for qualitative and quanti- tative sampling at representative reach and reachwide sampling scales. Evidence that populations had recovered in the year followin kile indicates gth i l lettee th evidenc; y rdY b e indicating that population failed s ha recoveo dt indicates ri d asterisletttee n byA th . indicate) rN k(* s that data wer t collecte eno speciee th r dt thafo sa t sampling scale. Abundance, schooling, and parental investment characteristics are also given for each species. For abundance and parental care, H = high, M = moderate, and L = low. For schooling behavior, Y = schooling, and N = nonschooling.

Qualitative sampling Quantitative sampling Representative Representative Parental Species reach Reachwide reach Reachwide Abundance Schooling care White shiner Y Y M Y H Crescent shiner Y Y H Y H Bluehead chub Y Y H Y H Central stoneroller N N H Y M Torrent sucker N N M Y L Black jumprock Y Y N Y L Y L Margined madtom N Y L N H Fanlail darter Y • Y LI N H Riverweed darter Y Y M N H Roanoke darter N Y N N M N L Roanoke logperch * L N N * N L

black jumprock population reacS - U hbe e th n i s sponsibl lace f concordancth k o r efo e across sam- tween qualitativ e yearsth t bu , e measure indicated pling scales . reachwide Ath t e scale samplee w , d that populations increased from 1992 to 1993. 15 erosional units in the KL, but at the represen- These differences can be explained if we consider tative-reach scale we sampled more than 50 quad- bot sociae hth l behavio naturae th d lran abundance rats from only 3 erosional units. Because of this, of this species. When we compare black jumprock the probability of estimating the true abundance reacheS D d san abundanc witS U he thath f n o tei r distributioo speciee th greatls f no swa y reduced the other 10 species, only the Roanoke logperch e representative-reacth at h scale, givee th n is less abundant. Although individual black jump- clumped distributio blace th f ko n jumprock r Fo . raret rockno ,e mossar t occu schooln ri s that range species with eithe a randor r uniformo m distri- in size from 5 to 40 individuals. It is the only bution, these sampling differences woul t havdno e specie thin i s s study that shows botabunw hlo - bee importants na . t presenAlthougno o e d th t e hw dance and schooling behavior (Table 3). In 1992, results here, we did quantify abundance and dis- most fish obtained in the US reach came from large tributio f Roanokno e logperc representae th t ha - schools capture limitea n di d numbe f quadratsro ; tive-reach scale. Given their naturall abunw ylo - however, in 1993 fish were more evenly distributed dance, Roanoke logperch were absent from most across quadrats. Althoug numbee hth f individo r - quadrats in US, KL, and DS reaches, which made uals captured was not different, differences in spa- statistical analysis of the data meaningless. tial distribution resulted in differences in the num- In summary, qualitative and quantitative data f quadrato r be s occupied. Therefore recome w , - sets gave consistent results both withi acrosd nan s men f presence-absenco e d us cautio e th n ni e data spatial scales ,notabl w witfe ha e exceptionsn I . as a measure of recovery for uncommon, schooling designing monitoring programs to assess fish pop- species like the black jumprock. ulation recovery following perturbations, we rec- If we look at comparisons across spatial scales, ommend the use of some type of reachwide esti- the results are concordant for Roanoke darter if mation technique (e.g., Hanki Reeved nan s 1988; we discount the reachwide qualitative measure for eithef Dollofo e rus alt qualitative fe . 1993th d an ) e previousle th y stated reasons. However alse w o f i , r quantitativo e measure f abundancso distrid ean - discoun e representative-reacth t h qualitativ- ere bution for species with either low natural abun- sults for the black jumprock, then comparisons dance or severely clumped spatial distributions. across spatial scales provide differing results for r specieFo f moderato s higo t e h abundancd an e this species. The combination of low abundance unifor randor mo m distributions, quantitative sam- and schooling behavior that resulted in differences plin reachwida t ga e scal r qualitativeo r quaneo - between qualitative and quantitative measures at titative sampling at the representative-reach scale the representative-reach scale could also be re- woul appropriatee db . FISH RECOVERY AFTER DISTURBANCE 905

Effects of Life History Roanoke darter to a high of slightly over 200 mm We observed differences in recovery pattern r blacfo s kL T jumproc bluehead kan d chub. Max- amon e 11gth species studie affectee th n di d reach imum age ranged from 3 years for the three darters of South Fork Roanoke. Previous studies have to 7 years for the Roanoke logperch (Jenkins and shown that recovery times vary among families, Burkhead 1994). Although familial affiliation t firsa e t reproag , - size at first reproduction, maximum size or age, duction, and maximum size or maximum age fail and reproductive guild (Detenbeck et al. 1992). provido t e meaningful explanation r recoverfo s y r resultsBaseou n o d, only factors relate- re o dt rate differences, variatio reproductivn i e behavior productive behavior seemed to play an important among the 11 study species does provide insight role in species recovery in the South Fork Roanoke into mechanisms influencing recovery. All 11 spe- River. e classifieb cien ca ss reproductiv a d e lithophils. There was no clear difference in recovery rates However, ther e differencear e e amounth n i f so t among families; some cyprinids and some percids parental investment in the selection and prepara- exhibited 1992 KL reach effects t otherbu ,d di s tion of the spawning site, and these differences not (Table 3). Although KL reach abundance of correspond with levels of population recovery ob- the torrent sucker was depressed in 1992, evidence reachL serveK e .199 n th dThrei foue n th i 2 r f eo for the black jumprock is equivocal; therefore, it species showing evidence of spill impacts (Roa- is difficult to make inferences about catostomids. noke darter, Roanoke logperch, and torrent sucker) e laccleaa f Th ko r indicatio f recoverno r lacyo k e simplar e lithophils l threal n eI . cases, pairr o s of recover e margineth y yb d madtom make- in s group spawnerf so s selec aren a t a containing grav- ferences about ictalurids problematic as well. el or pebble substrate in areas of higher water ve- Depressed Roanoke logperch abundance th n ei locity and, during the course of the spawning act, KL reach during 1992 does provide some support bury eggs in the upper layers of the spawning area for other studies that have shown that late-matur- (Jenkins and Burkhead 1994). The fourth species ing specie sloe sar recovew o t r from perturbations exhibiting kill effects in 1992, the central stone- (Detenbeck et al. 1992). However, there was little roller, shows slightly greater spawning site prep- variability in age at first reproduction for the spe- aration. Central stonerollers also select pebblr eo ciestudiede w s ; therefore s difficuli t i , mako t t e gravel substrat erosionan ei l areas t malebu ,g sdi inferences about the effect of this factor. Although and defend a shallow depression or pit in the se- the Roanoke logperch doe t initiallsno y spaw- nun lected area. Female central stonerollers then move thirs tiothee it l th d f ryearo specie l al , s examined int preparee oth d area matind ,an g takes place (Jen- initially spawn in either their first or second year kinBurkhead san d 1994). Ther evidenco n s ei f eo (Jenkin Burkhead san d 1994). postspawning parental care by any of these species There was little indication that maximum age or following egg deposition and fertilization. size played an important role in recovery rates. The minimal parental investment in the spawn- smallo Tw , short-lived species (fantail darted an r ing act by these four species contrasts with the riverweed darter) showed no effects from the spill more elaborate prespawning and postspawning be- in 1992, whil thira e d (Roanoke darter) showed havior of the five species that showed no spill ef- strong evidence of spill effects (Table 3). At the fect n 199i s 2 (Tabl . Bot3) e h fantail darted an r other extreme largee th , , long-lived Roanoke log- riverweed darter males select and defend breeding perch showed 1992 effects, but the bluehead chub sites. Adhesive eggs are deposited and fertilized t (Tabldidno . Althouge3) Roanoke hth e logperch on the underside of flat stones, and the male guards may live slightly longer tha blueheae nth d chu7 b( the nest aggresively during development. There is versu years)s5 , maximum length similae sar r fo r some evidence that secretory tissues in the skin of the two species (Jenkins and Burkhead 1994). Our fantail darter males may release bactericides or results contrast wit findinge hth f Detenbeco s t ke fungicides that further facilitat developmeng eeg t al. (1992) that indicated large, long-lived species (Mayden 1985; Jenkins and Burkhead 1994). should be slower to recover than small, short-lived Although there is little postspawning investment ones. However, as with age at first maturation, by the other three species, male bluehead chubs there was limited variability in maximum length undertake extensive nest-building behaviors that or age for our 11 study species. Maximum lengths are similar to those of many other species in the ranged from a low of approximately 80 mm total genus Nocomis. Large adult male bluehead chubs length (TL) for riverweed darter, fantail darter, and dig a pit in pebble or gravel areas and then refill 906 ENSIG ALT NE .

the excavated area with stones of relatively uni- local fish adaptatio o regionat n l geomorphology form size selected from the surrounding area. The and hydrology becomes apparent. Studies in effort expended by male bluehead chubs in nest drought-prone stream e midwesterth n i s n United constructio considerables ni , takin0 3 g o frot 0 m2 States have documented rapid recovery from h, with completed nests ranging in size from 35 stream defaunations associated with channe- de l cm to over 1 m in diameter (Jenkins and Burkhead watering (Larimor . 1959al t e - ; BayleOs d an y 1994). Following nest construction, females de- borne 1993). For most species and sites, recovery posit eggs in shallow trenches dug by the male in times were much less than 1 year, despite the fact the upstream edge of the pit; the eggs are fertilized that sites were located a significant distance from by the male and subsequently covered by stones. a sourc f potentiao e l recolonizers n thesI .- in e Bot white hth ecrescene shineth d an rt shinee ar r stances, the component species in the assemblage commonly observed nest associate e blueth f -o s adaptee ar periodio dt c large-scale disturbancd ean head chub, and large aggregations of males and exhibited rapid recovery. In contrast, the assem- females moundspawe th n no s formebluee th y -db blagmore th en ei benign South Fork Roanoky ema head chubs (Jenkins and Burkhead 1994; W. E. experience periodic disturbances associated with Ensign, personal observation). flooding t locabu , l refugia (i.e., backwater areas The extensive nest site preparation and, in the along stream margins, deep pools, velocity shelters case of the darters, nest site defense, certainly en- behind large substrate, etc. e probablar ) y abun- hance surviva earld an l y developmen eggf o td san dant. Defaunation probable ar s y limite smallo dt , larvae cleae Th . r difference observee w s 199n di 2 localized patche recolonizatiod san n requires only KL reach populations between the group of four minor redistributio e populationth - f o ex n r Fo . species with limited parental investment in their ample, Meffe and Sheldon (1990) found that fish progeny and the group of five species with sig- communitie blackwaten i s r stream e southth n i s- nificant investment suggests that factors that fa- eastern United States recovere preperturbatioo dt n cilitated surviva f earlo l y life stagee yeath rn i s levels 11 months after small-scale defaunations. following the manure spill played an important In a similar study in Illinois, Petersen and Bayley differencee rolth n ei recovern i s y rates (Tabl. e3) (1993) observed recovery from a similar experi- Detenbec t alke . (1992) suggested that different mental defaunation in just a few days. reproductive guilds have differential - ratere f o s Finally relativele th , y extensive immigratioe nw covery and that species that require generalized observed during the first year of recovery calls into spawning habitat should recover more quickly than questio resulte th na numbe f o s f studieso r that those that require specialized habitats. This may indicate warm water and cool water stream fish have be true when the original perturbation causes deg- limited hom evagilitw rangelo d yan s (Gerking radatio f specializeno d habitats whet bu , n physical 1953; McLeave 1964; HilGrossmad an l n 1987; habitat remains relatively unaffected (as in the Mundahl and Ingersoll 1989). Adult fish obtained South Fork Roanoke kill), factors that facilitate r observereacL o K middl e he th durin th n df i eo g early survival, and presumably rapid population the summer of 1992 moved a minimum of 3 km increase predominatey ma , . This inferenc furs i e - month8 e inth s followin fise th gh kill. This dis- ther strengthene differencey db - type pa f th eo n i s tance is at least two orders of magnitude greater rental investment by the species exhibiting rapid tha home nth e range sizes reporte previe th n di - recovery. Whil cyprinde eth s expend effor pren i t - ously cited studies. paring the spawning site before egg deposition and In summary, parental investmen earln i t y life development, the percids invest effort both in nest stages played an important role in the ability of site selection and egg maintenance during devel- species to recolonize South Fork Roanoke River resuld opmenten botn i e t hTh . cases shoule b d followin e fisth gh kill assessinn I . g management increased survival during the critical early life his- actions to be taken following large-scale pertur- tory stages. bations, resource managers should realize that even though the component species of a fish as- Other Factors semblag e adapte e uniquar th o dt e combination e datTh a obtaine thin di s stud providn yca - ein of hydrologic and geomorphologic conditions in a sights into factors other than life history tactics basin, variabilit lifn i y e history tactics within na that affect fish population recovery. If we compare assemblag greas ei t enough tha singla t e endpoint our results with other studies of the effects of a for assessin sufficiente gb recovert no y . yma Fur - similar large-scale disturbance importance th , f eo thermore, assemblage n regioni s s where large- FISH RECOVERY AFTER DISTURBANCE 907

scale perturbations occur infrequentle b y ma y nadian Journa f Fisherieo l d Aquatian s c Sciences more vulnerable to the cumulative impacts of re- 45:834-844. peated small-scale disturbances (e.g., siltation- pe , . GrossmanD Hill. G ,d J.an ,. 1987. Home range esti- mates for three North American stream fishes. Co- riodic flow reductions, etc.) becaus frequence eth y peia 1987:376-380. of disturbance need not be as great to prevent com- Hughes, R. M., T. R. Whittier, C. M. Rohm, and D. P. plete population recovery. Larsen. 1990. A regional framework for establish- ing recovery criteria. Environmental Management Acknowledgments 14:673-683. . BurkheadM Jenkins . N d . E.R ,an ., 1994. Freshwater Funds for this project were provided by the Vir- fishes of Virginia. American Fisheries Society. Be- ginia Department of Game and Inland Fisheries thesda, Maryland. anU.Se dth . FisWildlifd han e Service througn ha Larimore, R. W., W. F. Childers, and C. Heckrotte. 1959. 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Environmental Management 14:737- es: implications for population regulation. Canadian 753. Journal of Fisheries and Aquatic Sciences 49:2196- . ReevesHankinH . G . d G.. D ,1988an , . Estimating total 2218. fish abundanc d totaan e l habitat are n smali a l Received Septembe , 19922 r 4 streams base n visuao d l estimation methods- Ca . Accepted June 2, 1997