Great Basin Naturalist
Volume 54 Number 1 Article 2
2-25-1994
Effects of cobble embeddedness on the microdistribution of the sculpin Cottus beldingi and its stonefly prey
Roger J. Haro College of Agriculture, University of Idaho, Moscow, Idaho
Merlyn A. Brusven College of Agriculture, University of Idaho, Moscow, Idaho
Follow this and additional works at: https://scholarsarchive.byu.edu/gbn
Recommended Citation Haro, Roger J. and Brusven, Merlyn A. (1994) "Effects of cobble embeddedness on the microdistribution of the sculpin Cottus beldingi and its stonefly prey," Great Basin Naturalist: Vol. 54 : No. 1 , Article 2. Available at: https://scholarsarchive.byu.edu/gbn/vol54/iss1/2
This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Great Basin Naturalist 54(1), © 1994, pp. 64-70
EFFECTS OF COBBLE EMBEDDEDNESS ON THE MICRODISTRIBUTION OF THE SCULPIN COTTUS BELDINGI AND ITS STONEFLY PREY
Roger J. Haro1,2 and Merlyn A. Brusven1,3
AlwrnACT.-Laboratory experiments were undertaken to assess the effects of three levels of cobble embeddedness on the microdistribution of the sculpin Cottus beldingi and its stoncfly prey, Skwala americana. Experiments were con ducted separately and together as predator and prey in temperature- and flow-controlled artificial streams. Whcn tested either separately or together, both the predator sculpin and its stoneHy prey occurred in significantly greater number,~ on substrata having unemhedded cobbles than substrata having half- or completely cmbedded cobbles. Sloncfly densi ties were greater in substrata having unembedded cobbles even though predator densities within the more embedded cobble patches were significantly lowcr. These findings support the hypothesis that higher predator densities influence prey den"itie" less than the structural habitat quality oflInembedded-cobhle patches.
Key words: predator-prey, cobble embeddedness, nonletfwl effects, stonejlies, sculpins, nonpoint source sedimenta tum, COUllS beldingi.
Reduced summer flows and increased sedi that, under laboratory conditions, Paragnetina mentation in many western North American media (Plecoptera, Perlidae) selected larger streams may significantly diminish the size substrata over smaller ones in the presence of and availability of adequate microhabitat rainbow trout. patches for benthic fish and insects. Sedimen Sculpins hold a significant position in the tation from agricultural sources has been food web of Pacific Northwest stream commu linked to pronounced changes in the trophic nities and have been shown to reduce food structure of lotie fish assemblages (Berkman resources, food consumption, and the produc aud Rabeni 1987) and may affect macroinvcr tion of trout (Brocksen et aJ. 1968). Cottus tebrate community structure, further altering beldingi, the Paiute sculpin, is the most abun trophic relations within the lotic food web. dant fish species in Lapwai Creek (Kucera et Such trophic changes, in part, may result aJ. 1983), the stream investigated in this study. from alterations in prey rcfugia brought about This ambush predator feeds almost exclusive by the embeddedncss of cobble snbstrata. lyon benthic macroinvertebrates (Johnson Brusvcn and Rose (1981) found that cobble 1985). Finger (1982) reported that adult C. embeddedness significantly influeuccd the beldingi preferred coarse-grained substrata in vulnerability of two insect predators, Hesper an Oregon stream. In California, Card and operla pacifica (Plccoptcra, Pcdidae) aud Rhy Flittner (1974) found the highest densities of acophila vaccua (Trichoptera, Rhyacophili C. beldingi in rubble or gravel substrata. dae), to predation by Coitus rhotheus. They Skwala americana (Plecoptera, Perlodidae) is suggested high sculpin predation success in a common lotic stonefly found throughout west the embedded substrata was due to the loss of ern North America (Baumann et aJ. 1977). macroinvertebrate refugia under cobbles. Nymphs are important prey of C. beldingi Microhabitat shifts by macroinvertebrate (Johnson 1985) and are normally found in rel prey in response to vertebrate and macroin atively unsedimented, unembedded-cobble vertebrate predators have been reported by riffles (Short and Ward 1980). Tbey commonly several workers (Stein and Magnuson 1976, feed on small mayflies and midges (Fnller and Stein 1977, Peckarsky and Dodson 1980, Stewart 1977, Richardson and Gaufiu 1971). Peckarsky 1983). Feltmate et al. (1986) found Skwala americana is univoltine, with adult
j Department ofPlnnt, Soil a",1 Entomologieal Scien,"",,,, Collogo ofAgl'icnltun,. Univon;;ly ofIdaho, Mom:Jw. Idaho 1'3844-2.3.19. 21'n,,' 64 1994] PREDATOR AVOIDANCE AND STREAM SEDIMENTATION 65 emergence occurring from February through oratory. The streams were partitioned into July (Baumann et al. 1977). three 0.19-m2 sections bordered by a 0.04-m2 The purpose ofthis study was to determine sand area at each end (Fig. 1). the microdistribution of C. beldingi and UnchJorinated tapwater was recirculated Skwala americana, both separately and through tbe channels by electrical pumps together as predator and prey, when given (mean velocity, 2.44 cm s·I). Water tempera choices among three levels of cobble embed ture was maintained at 13.9°C with thermo dedness in an artificial stream. static refrigeration units placed within recir culating sumps. Water depth was held at 13.0 MATERIALS AND METHODS cm above the base substrate, thus assuring that all cobbles were fully submersed. Field Collection Substrate Treatments Lapwai Creek (46' 18'N, 116'43'W) drains Natural stream cohbles (62.0-127.0 mm, agricultural land in the Columhia River Basin principal axis) were collected from Lapwai 20 km east of Lewiston, Idaho. Field esti Creek. Cobhles were scrubbed with a hrush mates of sculpin density were made in Sep under hot tap water, dried, and labeled wi!b tember 1987 from riffles in Lapwai Creek and an identification number and orientation its tributaries. Sculpins were frightened into a arrow to enable replication of their spatial drift net attached to two wire-mesh side arrangement in either an unembedded or wings that sampled a rectangular 0.44-m2 half-embedded condition. Fifteen cobbles area. Adult sculpins (66.1 ± 9.4 mm) used in were randomly positioned in each of !be test the experiment were collected during Sep sections of the stream except for the simulat tember and October 1987. ed, fully embedded condition, which had no Late-instar stonefly nymphs (Skwala amer visible surface presence of cobbles. The cob icana) were collected with kick nets from !be bles covered ca. 60% of the two-dimensional same riffles from which sculpins were collect area of the unembedded and 50%-embedded ed. The nymphs were transported to the labo sections. ratory. To simulate a 50%-embedded condition, Preconditioning of Test Organisms balf ofeacb cobble's principal axis was c-ast in plaster of paris. The casts were later Riled Sculpins and stoneflies were acclimated in with a mixture of concrete and natural stream laboratory streams like those described by sand. After drying, the "half-casts were tex Brusven (1973). Ccbbles were placed in the tured with a wire brush and assigned an iden streams to provide cover, All organisms were tification number and directional arrow that acclimated for at least 48 h in holding streams corresponded to their natural-rock counter before each experiment. Sculpins were ran parts. domly selected 24 h before each expeliment, Two centimeters of washed stream sand isolated, and starved to better elicit hunger was spread over the bottom of eacb artiRcial and foraging behavior. stream to serve as a base substratum. Three cobble-embeddedness conditions were ran Experimental Stream Channels domly assigned among three stream sections. Two Plexiglas® streams (3.35 X 0.25 x In one section cobbles were placed on top of 0.20 m) were arranged side by side in the lab- the sand. In another section the "balf-casts" 1111 • SlIIIII 11.1 • SIIIIII 1. Ill Ilt. ''''' Fig. 1. Schematic diagram of an artificial channel .showing the stream sections and one cobble-cmbeddedness llrrangement: (U) = unemhedded cobbles. (II) = 5Q%.emhedded cobhles, (S) = lOO%·embedded cobbles. and (B) = sand buffer zooes. 66 GREAT BASIN NATURALIST [Volume 54 were positioned in the identical arrangement (i.e., upstream, midstream, and downstream). and orientation as their natural unembedded Each possible cobble arrangement was repli counterparts. They were placed directly on cated randomly in time (three times) for a the sand, thereby limiting access to their total of nine trials for each organism. A non under surfaces by the organisms studied. The parametric Kruskal-Wallis test with a posteri remaining section was left as a 2.0~cm layer of ori pairwise comparisons (Conover 1980) was sand and simulated a 100% cobble-embedded used to detect significant differences among condition with no cobbles evident on the sur mean-ranked numbers of organisms recov face. ered from three cobble-embeddedness condi Experimental Trials tions (Conover 1980). PREDATOR AND PREY-INTERACTIVE.-This Experimental trials ran for 20 h and were experiment examined predator-prey interac terminated at sunrise (photoperiod, 9 light: 11 tion when both the predator and prey were dark). Upon completion of a trial, water flow introduced into a common stream, Four stone was shut off and partitions were placed flies were placed into each ofthree sections 1 h between stream sections. Test organisms were prior to the introduction of sculpins (2/sec recovered from each section and counted. tion, 6/stream), In this experiment, trials were Animals recovered from the buffer sections run concurrently in two parallel streams, were not included in the statistical analysis. Each possible cobble arrangement (three) was Two experiments were conducted: (1) preda tor and prey were tested independently to replicated in time (four times) for a total of 24 assess noninteractive distribution, and (2) trials. This experiment assessed whether dis predator"and prey were tested together to tribution of either the sculpin predator or its assess interactive distribution. prey was altered in the presence of the other PREDATOR AND PREY-NONINTERACTIVE. species. Statistical tests similar to those This experiment examined habitat selection described in the first experiment were used to by the predator (sculpin) and prey (stonefly) detect significant differences among mean in absence of each other. Two parallel streams ranked numbers of organisms from three cob~ were used, one for the predator and one for ble-embeddedness conditions. the prey. Equal numbers of sculpins (2) and stoneflies (4) were introduced into each sec RESULTS tion (3 sections/stream) of the respective streams and allowed to freely distribute Predator and Prey-Noninteractive among the sections for 20 h. Sculpin stocking density in the artificial channel (6 fish/chan Sculpin numbers (Table 1) were signifi nel) approximated sculpin density in the field, cantly different between substrate-embed i.e., 6.9 fish m-2 (Haro 1988). dedness conditions (P < .001) when tested Three cobhle-embedded conditions were in absence of stonefly prey. Multiple com randomly assigned among stream sections parisons showed that mean-ranked sculpin TABLE 1. Kruskal-Wallis test statistic (1') and mean-ranked sculpin and stonefly counts (R/n;) among cobble-embed dedness conditions, Unique lowercase letters denote significantly different counts within both noninteractive and inter active predator and prey experiments. Sculpin Stonefly Treatment T R/n j T R/n; Noninteractive (n i = 18) 53,03*** 53.16"'** Unemhedded 4.88a 8.06a 50%-embedded 1.50b 3.17b lOO%-embedded 1.33b 1.39c Interactive (OJ = 24) 71.05*** 71.10*** Unembedded 5.83a 5.63a 500/o-emhedded 1.58b 2.75b 100%-embedded 1.38b 1.33c *••Kruskul- \\\,]Ii, tc~t (J'Tor rate, P s; .0001. Multiple c0111pal"iwn e'Tor nttc, P s; .005. 1994] PREDATOR AVOIDANCE AND STREAM SEDIMENTATION 67 10 o Unembedded iii 50%-embedded A I B III lOO%-embedded 8 ! ," ,,. i I , ...... , " ...... , . 6 j ! 4 ...... 1,...... i, , ! i 2 ...... "...... , , I o ! SCULPINS STONEFLIES Fig. 2. Mean numbers of (A) Cottus heldingi and (B) Skwala arnericana recover~d fr?JH t~\re: cobble·embeddedness conditions (n = 18) when tested noninteractively in separate stream channels. VertIcal hnes m(hcate 1 SD. numbers in unembedded-cobble sections Predator and Prey-Interactive were signiflcantly greater (P < .005) than in When placed together, sculpins and stone either the 50%- or 100%-embedded sections flies were distributed similarly, in proportion (Tahle 1, Fig. 2A); however, there was no dif ate numbers, among three cobble-embedded ference in ranked sculpin numbers between ness conditions as when tested separately the latter cobble-embedded conditions. When (Table 1). Greatest densities of sculpins and substrate effects were discounted, no differ stoneflies were in the unembedded-cobble ences were found when sculpin numbers sections (Fig. 3A, B). were analyzed by stream section. Stonefly numbers were 35, 20, and 15% Ranked stoneHy numbers were also signifi lower, respectively, than numbers recorded cantly different among substrate-embedded from unembedded, 50%, and 100% cobble-em ness conditions (P < .001) when tested in bedded sections without predators. Although absence of sculpin predators (Table 1). Fur stonefly densities were altered by predation, thennore, all multiple comparisons between numbers of stoneflies occupying the unem substrate conditions were significant (P < bedded-cobble substrata were more than dou .005). Like sculpins, stonefly nymphs were ble those found in the cobble-embedded sec most abundant in unembedded-cobble sub tions during the tests conducted without strata followed by 50% and 100% cobble predators. Furthermore, mean stonefly num embedded conditions (Fig. 2B). Nymphs were bers from the 50%- and 100%-embedded sub most often found on the undersides of unem strata were nearly identical between the two bedded cobbles and on tbe sides of 50% experiments. embedded cobbles. As with sculpins, when substrate effects were discounted, stoneHies DISCUSSION did not distribute themselves differentially within any particular section in the channel. Unembedded-cobble substrata supported At the conclusion of the experiment, nearly all the highest densities ofsculpins and stoneflies (99%) stonefly nymphs introduced were when tested botb independently and interac recovered alive. tively. We propose that spatial refugia afforded 68 GREAT BASIN NATURALIST [Volume 54 10 o Unembedded i B III SO%-embedded AI EI lOO%-embedded I 8 ...... , 6 .. " ...... , , " "" , "" . I ; 4 ...... ·····························r······; ...·· ...... i ; 2 " ...... m ...... i ...... ···.....· ...... " . :.1 iiiilii:,i!:::i;: mlli:;i:::!!:'; o .: ,. ",1;: 12.!j,.~,.1.l'~' L __l1,__1__ :;~jlf!l!i~)~:iij '~''''b'' SCULPINS STONEFLIES Fig. 3. Mean numbers of (A) Cottus beldingi and (B) Skwala americana recovered from three cohble-embeddedness conditions (n = 24) when tested interactively in streams. Vertical lines indicate 1 SD. by the unemhedded-cobble substrata influ Predators have been shown to have non enced the distribution of S. americana more lethal effects on prey by altering prey distri than the presence of vertebrate predators bution (Power and Matthews 1983, Sih 1987, occupying mutually similar habitats. We sub Kohler and McPeek 1989). However, results mit that if the probability of prey escapement from our study generally do not support this increases in unembedded cobbles because of type of response to predation. Our findings expeditious access to refugia, then the stone more closely approximate those of Sih et al. fly may tolerate a greater risk of predatory (1992), who reported that relative changes in attack. In theory, habitat-specific escape prey density were attributed almost entirely behavior can reinforce a prey's preference for to predation rather than predation-induced habitats shared by coevolved predators (Lima emigration. 1992). According to Peckarsky (1982), prey While we did not conduct stomach analysis that are smaller than their predators can effec on the sculpin predator to confinn prey con tively occupy interstitial spaces not habitable sumption in this study, earlier studies by by predators. Tbis hypothesis is supported by Johnson (1985) in Lapwai Creek reported the fact that significantly more stoneflies extensive predation of S. americana by C. occupied the 50%- tban 100%-embedded cob beldingi. Accordingly, we surmised that ble substrata, whereas sculpin densities found reduced densities of prey at the conclusion of within these embedded substrata were nearly an experiment having seulpins present were identical. Further, Davis and Warren (1965) due to predation alone. found that, in a laboratory channel similar to In the Held unembedded-cobble substrata one used in this study, prey consumption by likely offer better foraging conditions for S. Cottus perplexus signifIcantly decreased as americana, offsetting potential risks of sculpin Cott-us densities increased. High densities of predation. Siltation in rime hahitats reduces C. beldingi in the unemhedded-cobble sub macroinvertebrate prey densities, especially strata may have produced a similar interfer mayflies (McClelland and Brusven 1980, ence response, thereby reducing the potential Lenat et al. 1981, Peckarsky 1984), am! may predation pressure on S. americana. lower stonefly residence time within cobble- 1994] PREDATOR AVOIDANCE AND STREAM SEDIMENTATION 69 embedded patches. Short and Ward (1980) BERK1\'JAN, H. K, AND C. F. RABENJ. 1987. Effect of silta noted that low densities of S. americana in a tion on stream fish communities. Environmental Biology ofFishes 18: 285-294. Colorado mountain stream were not the result BROCKSEN, R. W., G. E. DAVIS, AND C. E. WARHEN. 1968. oflimited food, but of siltation from bank ero Competition, food consumption, and production of sion that rednced suitable habitat. sculpins and trout in laboratory stream commlmi· Macroinvertebrate densities from Lapwai ties. Journal ofWildlife Management 32: 51-75. Creek were much lower when the cobbles BRUSVEN, M. A. 1973. A closed system plexiglass stream for studying insect-fish-substrate relationships. Pro were 50-75% embedded than 0-25% embed gressive Fish Culturist 35: 87-89. ded (Haro 1988). However, differences in BHUSVEN, M. A., A.J.~D S. T. ROSE. 1981. Influence of sub macroinvertebrate abundance were not so strate composition and suspended sediment on great as to suggest prey was limiting to insect predation by the torrent sculpin, COtttlS rhotheus. Canadian Journal of Fisheries and Aquatic sculpins in these cobble-embedded substrata. Sciences 38: 1444-1448. In conclusion, unembedded-cobble sub CONOVER, W. J. 1980. Practical nonparametric statistics. strata in artificial streams provided spatial John Wiley and Sons, New York. 493 pp. refugia for macroinvertebrates from sculpin DAVIS, C. K, AND C. E. WARRE/';. 1965. Trophic relations predation. Stonellies continned to select this ofa sculpin in laboratory stream communities. Jour nal of Wildlife Management 29: 846-871. microhabitat even though it harbored poten FELTMATE, B. W., R. L. BAKER, AND P. J. POINTING. 1986. tially dangerous sculpin predators. Cobble Distribution of the stonefly nymph Paragnetina substrata can be greatly altered in sediment media (Plecoptera: Perlidae): influence of prey, laden, midorder streams draining agricultural predators, current speed, and substrate composi tion. Canadian Journal of Fisheries and Aquatic Sci lands (Haro 1988). Cobble impaction resulting ences 43: 1582-1587. in habitat degradation may destabilize ecolog FELTMATE, B. W., A/,;D D. D. WILLlAl\·lS. 1989. A test of ical relationships between organisms that crypsis and predator avoidance in the stonefly have coevolved in relatively silt-free and Paragnetina media (Plecoptera, Perlidae). Animal unembedded-cobble riffles. The importance Behavior 37: 992-999. FINGER, T. R. 1982. Interactive segregation among three of substrate condition in mediating predator species of sculpins (Cottus). Copeia 1982: 68Q.....694. prey interactions in streams is becoming more FULLER, R. L., AND P. S. RAND. 1990. Influence of sub evident (Feltmate and Williams 1989, Gilliam strate type on vulnerability of prey to predacious et a!. 1989, Fuller and Rand 1990). Thus, the aquatic insects. Journal oftbe North American Ben mechanisms by which and the extent to which thological Society 9: 1-8. FULLEH, R. L., AND K. \V. STEWART. 1977. The food nonpoint source sediment perturbations alter habits of stoneflies (Plecoptera) in the Upper Gun lotic food-web dynamics warrant careful con nison River, Colorado. Environmental EntomoJos'Y sideration when evaluating stream ecosystems 6,293-302. in the future. CARD, R., AND C. A. FLIrfNER. 1974. Distribution and abundance of fishes in Sagehen Creek, California. Journal of Wildlife Management 38: 347-358. ACKNOWLEDC:\IENTS GILLIA\.f, J. F., D. F. FRAZER, AND A. M. SABAT. 1989. Strong effects offoraging minnows on a stream ben The help of Russell Biggam and Ian Waite thic invertebrate community. EcoloS')' 70; 445-452. in the field and laboratory was indispensable. HARO, R. J. 1988. Agricultural nonpoint source pollution Statistical aid by Drs. Kirk Steinhorst, Uni impacts on macrobenthic fauna within the Lapwai versity of Idaho, and Gary Fowler, University Creek watershed, Idaho. Unpublished master's the of Michigan, was greatly appreciated. This sis, University of Idaho, Moscow. 237 pp. JOHNSON, J. H. 1985. Comparative diets of Paiute sculpin, research was supported in part by a grant speckled dace, and subyearling steelhead trout in from the Idaho Water Resources Research tributaries of the Clemwater River, Idaho. North Institute, Project No. 14-08-000l-G1419-03. west Science 59: 1-9. It is published as research paper number KOHLER, S. 1., AND M. A. MCPEEK. 1989. Predation risk 89718, Idaho Agricultural Experiment Sta and the foraging behavior of competing stream insects. Ecology 70: 1811-1825. tion, University ofIdaho. KUCERA, P. A., J. H. JOHNSON, AND M. A. BEAlL 1983. A biological and physical inventory of the streams LITERATURE CITED within the Nez Perce Reservation. Bonneville Power Administration, Final Report, Lapwai, Idaho. BAUMANN, R. W., A. R. GAUFIN, AND R. F. SURDICK. 159 pp. 1977. The stoneflies (Plecoptera) of the Rocky LENAT, D. R., D. L. PENROSE, AND K. W. EAGLESON. Mountains. Memoirs of the American Entomologi 1981. Variable effects of sediment addition on cal Society 31: 1-208. stream benthos. Hydrobiologia 79: 187-194. 70 GREAT BASIN NATURALIST [Volume 54 LIMA, S. L. 1992. Strong preferences for apparently dan RICHARDSON, J. W., AND A. R. GAUFIN. 1971. Food habits gerous habitats? A consequence of differential of some western stonefly nymphs. Transactions of escape from predators. Dikos 64: 597-600. the American Entomological Society 97: 91-121. MCCLELI...... ND, W. T., AND M. A. BUDSVEN. 1980. Effects SnORT, R. A., AND J. V. WARD. 1980. Life cycle and pro ofsedimentation on the behavior and distribution of duction of Skwala rarallela (Frison) (Plecoptera: rime insects in a laboratory stream. Aquatic Insects Perlodidae) in a Colorado montane stream. Hydro 2,161-169, biologia 69: 273-275. PECKt\I\SKY, B. L. 1982. Aquatic insect predator-prey rela Sm, A. 1987. Predators and prey lifestyles: an evolution tions. Bioscience 32: 261-266. ary and ecological overview. Pages 203-224 in C. W. __,.1983. Use of behavioral experiments to test eco Kerfoot and A. Sih, eds., Predation-direct and in logical theory in streams. Pages 79-98 in J. R. direct impacts on aquatic communities. University Barnes and G. W. Minshall, eds., Stream ecology; Press ofNew England, Hanover, New Hampshire. application and testing of general ecological theory. Sm, A., L. B. KATS, AND R. D. MOORE. 1992. Effects of Plenum Press, New York. predation of sunfish on density, drift, and refuge use --c-" 1984. Predator-prey interactions among aquatic of stream salamander larvae. Ecology 73: insects. Pages 196-254 in V. H. Resh and D. M. 1418-1430, Rosenberg, eds., The ecology of aquatic insects. STEIN, R. A. 1977. Selective predation, optimal foraging, Praeger, New York. and the predator-prey interaction between fish and PECKAl{SKY, B. L., AND S. I. DODSON. 1980. Do stonefly crayfish. Ecology 58: 1237-1253. predators influence benthic distribution in streams? STEIN, R. A, AND J. J. MAGNUSON. 1976. Behavioral Ecoloh'Y 61: 1275-1282. response of crayfish to a fish predator. Ecology 57: POWEl'., M. E., AND W. J. MKrnmws. 1983. Algae-grazing 571-561. minnows (Campostoma anoma!um), piscivorous bass (Microptcrus spp.), and the distribution of attached algae in small prairie-margin stream. Oecologia 60: Received 23 November 1991 328-332, Accepted 24 August 1993