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Top-down Effect of Fish Predation in Virginia Headwater Streams
Elise Wach and Randolph M. Chambers

Northeastern Naturalist, Volume 14, Issue 3 (2007): 461–470

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2007 NORTHEASTERN NATURALIST 14(3):461–470 Top-down Effect of Fish Predation in Virginia Headwater Streams Elise Wach1 and Randolph M. Chambers2,* Abstract - We completed laboratory-feeding studies that demonstrated preference of the headwater stream fishes Gambusia holbrooki (Mosquitofish) and Clinostomus funduloides (Rosyside Dace) for smaller Gammarus pseudolimnaeus (amphipods) over larger ones. We also submerged oak leaf-litter bags in sections of streams with and without these fish predators. After three weeks, the mean number ± s.e. of amphipods per litter bag in streams with fish was significantly lower (289 ± 50 vs. 978 ± 122) and the average size of amphipods was significantly larger (13.9 ± 0.1 mg vs. 8.1 ± 0.1 mg), relative to streams without fish. The quantity and quality of leaf litter, however, were not significantly different. Top-down predation may have altered the population structure of stream-dwelling amphipods, but did not change leaf decomposition over the time of the study. Introduction Headwater stream ecosystems are predominantly heterotrophic (Fisher and Likens 1972), where food-web dynamics and maintenance of community structure are dependent upon the input of organic matter—primarily as leaf litter—from adjacent terrestrial environments (Cummins et al. 1972, Short and Maslin 1977, Wallace et al. 1997, Webster et al. 1995). In these detritus-based streams, factors that control the decomposition of allochthonous organic matter determine the transfer of energy and nutrients to higher trophic levels (Creed and Reed 2004, Hall et al. 2000, Wallace et al. 1999). For example, the action of invertebrate “shredder” organisms that break down leaf litter into smaller physical pieces is dependent on litter quality (Motomori et al. 2001) and can account for 25% of the loss of leaf mass (Cuffney et al. 1990, Newman 1990, Peterson and Cummins 1974). Shredder feces and small leaf fragments are rich substrates for microbes and constitute a high-quality food source for filter-feeding organisms that remove these particles from the water column (Cummins et al. 1972). Shredder biomass, in turn, is food for higher trophic levels such as fish (Dahl and Greenberg 1996, Wipfli 2005). In addition to the bottom-up controls of food-web dynamics, top-down regulation in freshwater streams has been demonstrated by several studies (Gibson et al. 2004, Malmqvist 2002, Peckarsky and Dodson 1980, Walde and Davies 1984). Fish predation can reduce stream invertebrate volume up to 90%, relative to sections of stream without fish (Gilliam et al. 1989). 1Biology Department, University of Southern California, Los Angeles, CA. 2Biology Department and Keck Environmental Lab, College of William and Mary, Williamsburg, VA . *Corresponding author - rmcham@wm.edu. 462 Northeastern Naturalist Vol. 14, No. 3 Some fish species exhibit size preferences for smaller invertebrates (Schlosser and Ebel 1989) or larger invertebrates (Gilliam et al. 1989), whereas other species are thought to maintain a mixed-size diet of invertebrates, regardless of relative or absolute abundance of different prey sizes (Bence and Murdoch 1986). Because fish predation can alter the distribution of shredders in streams, the influence of fish predation could extend down two trophic levels and change the rate of leaf-litter breakdown (Konishi et al. 2001, Obendorfer et al. 1984, Ruetz et al. 2002). The objective of the present study was to determine the potential influence of fish predation on food-web dynamics in three headwater streams on the southeastern Virginia coastal plain. In all streams, the most abundant macroinvertebrate was the leaf-shredding amphipod Gammarus pseudolimnaeus Bousfield. We determined experimentally the abundance and sizes of amphipods occupying leaf litter in sections of streams with and without fish, for comparison with laboratory determinations of fish-feeding preferences on different sizes of amphipods. We also compared changes in leaf-litter biomass and quality, to determine whether top-down controls of shredder populations might extend to the base of the food web. Methods Study site This study was conducted in three headwater streams leading into Lake Matoaka in Williamsburg, VA: Strawberry Creek, Pogonia Creek, and Berkeley Creek (Fig. 1). Each of the stream sub-watersheds is dominated by second-growth hardwood forest > 100 years old (Table 1). Stream water quality was determined on a single date in June 2005 from spot sampling and analysis for dissolved nutrients using standard analytical methods (Parsons et al. 1984). Two sites per stream were chosen for the study based on the presence or absence of fish in downstream and upstream locations, respectively (Fig. 1). In both locations, stream depth was < 10 cm, and the water was clear. Besides the presence of fish, downstream locations in closer proximity to Lake Matoaka were characterized qualitatively by slightly broader stream channels, finer sediment in the streambed, and slower moving water. The primary source of organic matter in these streams is leaf litter from the surrounding forest, and instream algal production is very low (Mahon Table 1. Sub-watershed area, forest coverage, and water quality in the Lake Matoaka drainage basin in southeastern Virginia. SRP = soluble reactive phosphorus. BD = below detection. Water quality (􀂗g/L) Sub-watershed Area (km2) % forest SRP NO2 -+NO3 - NH4 + Strawberry Creek 0.61 72 39 421 53 Pogonia Creek 0.33 96 BD 76 36 Berkeley Creek 0.71 84 BD 560 94 2007 E. Wach and R.M. Chambers 463 1997). The most abundant stream invertebrate by far is the amphipod Gammarus pseudolimnaeus, a leaf shredder (Zehmer et al. 2002) that numerically comprises >95% of individuals from all species (G.M. Capelli, College of Williams and Mary, Williamsburg,VA, pers. comm.). From sweep-net sampling, Gambusia holbrooki Girard (Mosquitofish) and Clinostomus funduloides Girard (Rosyside Dace) were the most abundant fish in the streams, with fewer Lepomis spp. (Sunfish) and Semotilus atromaculatus Mitchill) (Creek Chub) (Saerom Park, Williams College,Williamstown, MA, pers. comm.). The upstream absence of fish was indicated by extensive, unsuccessful seining and sweep netting throughout the stream channel and along undercut creekbanks. Fish predation on amphipods Rosyside dace and mosquitofish were collected during the second week of June 2005 and held in aquaria at the laboratory. Amphipods were collected from Strawberry Creek and held in a separate aquarium. For fishpredation experiments, a single fish was measured for total length to the nearest mm and placed into a 600-ml beaker filled with stream water and containing 10 live amphipods that had been blotted dry and measured individually for mass to the nearest 0.1 mg (wet weight). Weighing amphipods after blotting with absorbent paper is a repeatable measure with <0.05% error (Zehmer et al. 2002). In each beaker, we provided the fish a range of amphipod sizes, from as small as 0.4 mg to as large as 19.5 mg. After 24 Figure 1. Site map of the Lake Matoaka watershed on the Virginia coastal plain (76.72ºW, 37.27ºN) showing the location of sub-watershed boundaries (solid lines), headwater streams (dashed lines), and mesh bags (crosshatched circles) in areas with and without fish (downstream and upstream, respectively). 464 Northeastern Naturalist Vol. 14, No. 3 hours, the fish was removed and any remaining amphipods were blotted dry and weighed to determine which ones had been consumed by the fish. A total of 30 Rosyside Dace and 22 Mosquitofish were tested. Three separate beakers containing 10 amphipods and no fish lost no amphipods over the 24 hours, demonstrating that amphipod loss was likely due to consumption by fish. The average weights of live amphipods eaten and uneaten by Rosyside Dace and Mosquitofish were compared using t-tests. Amphipod abundance and size in streams Nylon bait bags (0.25” mesh size) were filled with 50 grams of air-dried, mixed leaf litter of Quercus alba L.(white oak), Q. rubra L. (red oak) and Q. michauxii Nutt. (swamp chestnut oak) collected from the forest floor in the Lake Matoaka watershed. In each of the three streams, three bags were tethered and submerged in a line across the stream channel in both upstream and downstream locations. Twice per week, all bags were lifted off the sandy streambed and flipped over to keep bags from being buried. In the laboratory, three additional control bags were placed in deionized water, and the water was changed every week. After three weeks, all bags from each upstream and downstream location and the three control bags were harvested. Each bag was shaken for a total of one minute in three separate buckets of water containing a mesh-screen bottom to remove sand and isolate amphipods. All amphipods from the rinses were blotted dry and weighed as a group, then a 10-cm3 sub-sample was weighed, and all amphipods in the sub-sample were counted to calculate average amphipod weight. The sub-sample measurements of number and weight were used with group weight to calculate the total number of amphipods per bag. Amphipod weight and abundance between upstream and downstream locations were compared using t-tests. Litter weight and CNP analysis After rinsing to remove amphipods and sand, the harvested bags of litter were then dried in an oven at 80 ºC and weighed. Elemental analysis for total carbon (C) and nitrogen (N) was completed on milled litter using a Perkin- Elmer 2400 Analyzer. Total phosphorus (P) was determined using an ashing/ acid-extraction method after Chambers and Fourqurean (1991). Upstream and downstream litter weights were compared using a t-test. ANOVA with post-hoc comparisons was used to test the differences in average C, N, and P content among control, upstream, and downstream litter. Results Fish predation on amphipods For both Rosyside Dace and Mosquitofish, smaller amphipods were consumed relative to larger ones (t-tests, P < 0.01, Fig. 2). Twenty-two Mosquitofish, ranging in size from 20 to 45 mm, consumed a total of 178 amphipods weighing an average ± s.e. of 4.9 ± 0.3 mg. The 70 uneaten 2007 E. Wach and R.M. Chambers 465 amphipods weighed an average of 9.6 ± 0.6 mg. Similarly, for 28 trials with Rosyside Dace, ranging in size from 44 to 52 mm, the fish consumed 224 amphipods weighing an average of 5.8 ± 0.3 mg. The 62 uneaten amphipods weighed an average of 11.4 ± 0.4 mg. Amphipod abundance and size in streams Averaged across all three streams, more than three times as many amphipods were recovered from nine litter bags collected upstream in the absence of fish than downstream in the presence of fish: an average ± s.e. of 978 ± 122 amphipods upstream versus 289 ± 50 amphipods downstream (P < 0.001). The pattern of greater average numbers of amphipods was observed for all three streams individually (Fig. 3). Further, the average weight of amphipods collected from nine upstream litter bags in the absence of fish was significantly smaller than for amphipods collected from downstream litter bags in the presence of fish (N = 9, average ± s.e. of 8.1 ± 0.1 mg upstream versus 13.9 ± 0.1 mg downstream, P < 0.01). Litter bags from downstream locations in the presence of fish contained fewer, larger amphipods relative to upstream locations, which contained more abundant, smaller amphipods. The difference in amphipod size paralleled the pattern of fish predation on amphipods, for which smaller amphipods were consumed preferentially to larger amphipods (Fig. 2). Figure 2. Mean weight (+ standard error) of amphipods eaten and uneaten by G. holbrooki (Mosquitofish) and C. funduloides (Rosyside Dace), and of amphipods collected in field litter bags from upstream (fish absent) and downstream (fish present) locations. 466 Northeastern Naturalist Vol. 14, No. 3 Litter weight and CNP analysis After three weeks of submergence in streams, dry-litter weight was not significantly different between upstream and downstream locations (N = 9, average ± s.e. of 47.4 ± 1.2 g upstream versus 46.2 ± 2.1 g downstream, t-test P > 0.05). Some of the litter bags weighed more than the initial 50 g, which we attributed to fine sand that could not be fully washed out of the bags. Litter that had been submerged for three weeks in deionized water in the lab had, on average, 6% higher carbon and 25% lower nitrogen and phosphorus content, relative to litter submerged in streams (Fig. 4). Despite these significant differences between control and field litter (ANOVA, P < 0.05), there were no significant post-hoc differences in elemental content between upstream and downstream locations. Discussion Results of the current study demonstrate the impact of fish on trophic structure in headwater streams on the coastal plain of Virginia. Both amphipod size (Fig. 2) and number (Fig. 3) were shown to be altered by fish predation, revealing a top-down influence of fish predation on the dominant invertebrate food source in the streams (Zehmer et al. 2002). The downstream presence of fish influences energy processing and resource utilization in headwater stream communities (Baxter et al. 2004, Vannote et al. 1980). Although many studies have shown effects of fish predation on prey populations in streams (Gibson et al. 2004, Malmqvist 2002, Peckarsky et al. Figure 3. Mean number (+ standard error) of amphipods per litter bag in upstream and downstream locations from all three streams, after three weeks (N = 9). 2007 E. Wach and R.M. Chambers 467 Figure 4. Posthoc comparison of elemental content of litter bags from upstream and downstream locations relative to laboratory c o n t r o l s (mean + standard error). Asterisks denote values significantly different from controls (P less than 0.05). No comparisons between upstream and downstream samples were significantly different. 468 Northeastern Naturalist Vol. 14, No. 3 2005, Zhao et al. 2006), fewer studies have demonstrated how alteration of prey density can impact lower trophic levels (Konishi et al. 2001, Obendorfer et al. 1984, Ruetz et al. 2002). In the current study, we saw no difference in leaf-litter quantity or quality in sections of streams with and without fish (Fig. 4), nor among streams with different water-quality characteristics (Table 1). In the absence of large populations of other invertebrate detritivores, our data suggest that the shredding of leaves by fewer, larger amphipods in the presence of fish is similar to the action by more abundant but smaller amphipods in the absence of fish. Leaf breakdown by macroinvertebrates, however, can vary due to many factors including shredder density (Chaffin et al. 2005), shredder size (Cummins et al. 1972), leaf type (Lecerf et al. 2005), and water-borne chemical cues (DeLange et al. 2005). Also, leaf breakdown can be driven largely by physical action, although the large numbers of G. pseudolimnaeus and the ability of this species to digest cellulose (Chamier 1991) suggest the strong influence of biological activity. A longer-term study of litter changes might detect changes in breakdown rate as a function of amphipod number and size. Finally, downstream drift can reduce the upstream amphipod population size, with amphipods using litter both as a source of food and as potential refuge from predators downstream (Friberg and Jacobsen 1994, Hoffmann 2005). Stream invertebrate populations must offset losses to downstream drift through both upstream migration and local reproduction (Kopp et al. 2001, Williams and Williams 1993). The observed pattern of greater amphipod number and smaller size upstream is consistent with these general life-history characteristics of drift organisms. Thus, both top-down regulation by fish and bottom-up control by leaf litter appear to influence G. pseudolimnaeus populations in Virginia headwater streams. Acknowledgments This research using live vertebrate animals was completed under IACUC project #0418 at the College of William and Mary. Thanks to Timothy Russell and Sarah Gruber for laboratory assistance. The first author was an undergraduate REU student funded by NSF-EAR grant #0243751—Interdisciplinary Watershed Studies at the College of William and Mary. Literature Cited Baxter, C.V., K.D. Fausch, M. Murakami, and P.L. Chapman. 2004. Fish invasion restructures stream and forest food webs by interrupting reciprocal prey subsidies. Ecology 85:2656–2663. Bence, J.R., and W.W. Murdoch. 1986. Prey-size selection by the Mosquitofish: Relation to optimal-diet theory. Ecology 67:324–336. Chaffin, J.L., H.M. Valett, J.R. Webster, and M.E. Schreiber. 2005. Influence of elevated arsenic on leaf breakdown in an Appalachian headwater stream. Journal of the North American Benthological Society 24:553–568. Chambers, R.M., and J.W. Fourqurean. 1991. Alternative criteria for assessing nutrient limitation of a wetland macrophyte (Peltandra virginica (L.) Kunth). Aquatic Botany 40:305–320. 2007 E. Wach and R.M. Chambers 469 Chamier, A.C. 1991. Cellulose digestion and metabolism in the freshwater amphipod Gammarus pseudolimneus Bousfield. Freshwater Biology 25:33–40. Cuffney, T.F., J.B. Wallace, and G.J. Lugthart. 1990. Experimental evidence quantifying the role of benthic invertebrates in organic-matter dynamics of headwater streams. Freshwater Biology 23:281–299. Cummins, K.W., R.C. Peterson, F.O. Howard, J.C. Wuycheck, and V. Holdt. 1972. The utilization of leaf litter by stream detritivores. Ecology 54:336–345. Creed, R.P., and J.M. Reed. 2004. Ecosystem engineering by crayfish in a headwater stream community. Journal of the North American Benthological Society 23:224–236. Dahl, J., and L. Greenberg. 1996. Impact on stream benthic prey by benthic- vs. driftfeeding predators: A meta-analysis. Oikos 77:177–181. De Lange, H.J., M. Lurling, B. Van den Borne, and E.T.H.M. Peeters. 2005. Attraction of the amphipod Gammarus pulex to water-borne cues of food. Hydrobiologia 544:19–25. Fisher, S.G., and G.E. Likens. 1972. Stream ecosystem: Organic energy budget. Bioscience 22:33–35. Friberg, N., and D. Jacobsen. 1994. Feeding plasticity of 2 detritivore-shredders. Freshwater Biology 32:133–142. Gibson, C.A., R.E. Ratajczak, and G.D. Grossman. 2004. Patch-based predation in a southern Appalachian stream. Oikos 106:158–166. Gilliam, J.F., D.F. Fraser, and A.M. Sabat. 1989. Strong effects of foraging minnows on a stream benthic invertebrate community. Ecology 70:445–452 Hall, R.O., J.W. Wallace, and S.L. Eggert. 2000. Organic-matter flow in stream food webs with reduced detrital resource base. Ecology 81:3445–2463. Hoffmann, A. 2005. Dynamics of fine particulate organic matter (FPOM) and macroinvertebrates in natural and artificial leaf packs. Hydrobiologia 549:167–178. Konishi, M., S. Nakano, and T. Iwata. 2001. Trophic cascading effects of predatory fish on leaf-litter processing in a Japanese stream. Ecological Research 16:415–422. Kopp, M., J.M. Jeschke, and W. Gabriel. 2001. Exact compensation of stream drift as an evolutionarily stable strategy. Oikos 92:522–530. Lecerf, A., M. Dobson, C.K. Dang, and E. Chauvet. 2005. Riparian plant species loss alters trophic dynamics in detritus-based stream ecosystems. Oecologia 146:432–442. Mahon, S. 1997. Distribution and ecology of freshwater amphipoda in the Lake Matoaka/College Woods area, Williamsburg, Virginia. M.A. Thesis. The College of William and Mary, Williamsburg, VA. 39 pp. Malmqvist, B. 2002. Aquatic invertebrates in riverine landscapes. Freshwater Biology 47:679–694. Motomori, K., H. Mitsuhashi, and S. Nakano. 2001. Influence of leaf-litter quality on the colonization and consumption of stream invertebrate shredders. Ecological Research 16:173–182. Newman, R.M. 1990. Effects of shredding-amphipod density on watercress Nasturtium officinale breakdown. Holarctic Ecology 13:293–299. Obendorfer, R.Y., J.V. McArthur, J.R. Barnes, and J. Dixon. 1984. The effect of invertebrate predators on leaf-litter processing in an alpine stream. Ecology 65:1325–1331. Peckarsky, B.L., and S.I. Dodson. 1980. Do stonefly predators influence benthic distributions in streams? Ecology 61:1275–1282. Peckarsky, B.L., J.M. Hughes, P.B. Mather, M. Hillyer, and A.C. Encalada. 2005. Are populations of mayflies living in adjacent fish and fishless streams genetically differentiated? Freshwater Biology 50:42–51. 470 Northeastern Naturalist Vol. 14, No. 3 Parsons, T.R., Y. Maita, and C.M. Lalli. 1984. A Manual of Chemical and Biological Methods for Seawater Analysis. Pergammon Press, New York, NY. Peterson, R.C., and K.W. Cummins. 1974. Leaf processing in a woodland stream ecosystem. Freshwater Biology 4:343–368. Ruetz, C.R., R.M. Newman, and B. Vondracek. 2002. Top-down control in a detritus-based food web: Fish, shredders, and leaf breakdown. Oecologia 132:307–315. Schlosser, I.J., and K.K. Ebel. 1989. Effects of flow regime and cyprinid predation on a headwater stream. Ecological Monographs 59:41–57. Short, R.A., and P.E. Maslin. 1977. Processing of leaf litter by a stream detritivore: Effect on nutrient availability to collectors. Ecology 58:935–938. Vannote, R.L., G.W. Minshall, K.W. Cummings, J.R. Sedell, and C.E. Cushing. 1980. The river-continuum concept. Canadian Journal of Fisheries and Aquatic Sciences 37:130–137. Walde, S.J., and R.W. Davies. 1984. Invertebrate predation and lotic prey communities: Evaluation of in situ enclosure/exclosure experiments. Ecology 65:1206–1213. Wallace J.B., T.F. Cuffney, S.L. Eggert, and M.R. Whiles. 1997. Stream organic matter inputs, storage, and export for Sattelite Branch at Coweeta Hydrologic Laboratory, North Carolina, USA. Journal of the North American Benthological Society 16:67–74. Wallace, J.B., S.L. Eggert, J.L. Meyer, and J.R. Webster. 1999. Effects of resource limitation on a detrital-based ecosystem. Ecological Monographs 69:409–442. Webster, J.R., J.B. Wallace, and E.F. Benfield. 1995. Streams and rivers of eastern United States. Pp. 117–187, In C.E. Cushing, K. Cummins, and G.W. Minshall (Eds.). River and Stream Ecosystems. Elsevier Press, Amsterdam, The Netherlands. Williams, D.D., and N.E. Williams. 1993. The upstream–downstream movement paradox of lotic invertebrates: Quantitative evidence from a Welsh mountain stream. Freshwater Biology 30:199–218. Wipfli, M.S. 2005. Trophic linkages between headwater forests and downstream fish habitats: Implications for forest and fish management. Landscape and Urban Planning 72:205–213. Zehmer, J.K., S.A. Mahon, and G.M. Capelli. 2002. Calcium as a limiting factor in the distribution of the amphipod Gammarus pseudolimnaeus. American Midland Naturalist 148:350–362. Zhao, X.X., M.G. Fox, and D.C. Lasenby. 2006. Effect of prey density, prey mobility, and habitat structure on size selection and consumption of amphipods by a benthic-feeding fish. Archiv Für Hydrobiologie 165:269–288.