Feeding Ecology of Brook Silverside, Golden Shiner, and Subyearling Pumpkinseed in a Lake Ontario Embayment

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1 Notes Feeding Ecology of Brook Silverside, Golden Shiner, and Subyearling Pumpkinseed in a Lake Ontario Embayment James H. Johnson,* Marc A. Chalupnicki, Ross Abbett, Avriel R. Diaz, Christopher C. Nack U.S. Geological Survey, Tunison Laboratory of Aquatic Science, Great Lakes Science Center, 3075 Gracie Road, Cortland, New York, Abstract Fish feeding ecology has been shown to vary over a 24-h period in terms of the prey consumed and feeding intensity. Consequently, in order to best determine the interspecific feeding associations within a fish community, examination of the diet at multiple times over a 24-h period is often necessary. We examined the diel feeding ecology of three fish species that were numerically dominant in a Lake Ontario embayment during summer. The diet of each of the three species, young-of-year Pumpkinseed Lepomis gibbosus, Golden Shiner Notemigonus crysoleucas, and Brook Silverside Labidesthes sicculus, was distinct with no significant overlap in diet composition occurring within any of the 4-h time intervals. The diet composition of each species suggested that Brook Silverside were feeding at the surface (terrestrial invertebrates and aquatic surface dwelling hemipterans), whereas young-of-year Pumpkinseed (amphipods) and Golden Shiner (tipulids) were feeding on different benthic prey. Differences in feeding periodicity were most pronounced for young-of-year Pumpkinseed. Our findings provide valuable insights on interspecific feeding associations among these three fish species during summer in a Lake Ontario embayment. Keywords: Pumpkinseed; Brook Silverside; Golden Shiner; feeding ecology Received: September 26, 2015; Accepted: January 3, 2017; Published Online Early: January 2017; Published: June 2017 Citation: Johnson JH, Chalupnicki MA, Abbett R, Diaz AR, Nack CC Feeding ecology of brook silverside, golden shiner, and subyearling pumpkinseed in a Lake Ontario embayment. Journal of Fish and Wildlife Management 8(1): ; e x. doi: / jfwm-075 Copyright: All material appearing in the Journal of Fish and Wildlife Management is in the public domain and may be reproduced or copied without permission unless specifically noted with the copyright symbol &. Citation of the source, as given above, is requested. The findings and conclusions in this article are those of the author(s) and do not necessarily represent the views of the U.S. Fish and Wildlife Service. * Corresponding author: jhjohnson@usgs.gov Introduction Diel variation in both diet composition and feeding intensity of fishes has long been recognized (Keast and Welsh 1968), and identifying these patterns is considered important in understanding trophic linkages within fish communities. Because of these patterns, samples to describe diet that are taken at only one time period often do not provide a clear understanding of the feeding ecology for a fish species. In order to best describe the daily diet of a fish species, samples should be taken at regular intervals over a 24-h period (Beauchamp 1990). However, this process requires that multiple samples be taken that encompass diurnal, crepuscular, and nocturnal periods. Moreover, not only does diel sampling require considerably more effort in the field, it also substantially increases the number of samples that must be processed and examined in the laboratory. Although diel diet studies have been carried out on nongame species, more comprehensive diel assessments have been made on game species (Helfman 1981) because of their economic importance. Diel feeding studies are not only important to best understand the feeding ecology of an individual species, they are also useful in assessing interspecific species associations (Reebs 2002; Railsback et al. 2005). For example, syntopic species may feed on similar prey taxa during specific time intervals or may exhibit differences in periods of peak food consumption (Moyle 1973; Mendelson 1975). Both of these feeding strategies may reduce interspecific competition (Ward et al. 2006). Moreover, understanding the diel feeding ecology of syntopic native fish species is important to help Journal of Fish and Wildlife Management June 2017 Volume 8 Issue 1 240

2 determine how they share available food resources and how existing trophic interactions may be at risk from incursions by invasive species such as Round Goby Neogobius melanostomus. Consequently, we examined the diel feeding ecology of Brook Silverside Labidesthes sicculus, Golden Shiner Notemigonus crysoleucas, and young-of-year Pumpkinseed Lepomis gibbosus in a Lake Ontario embayment during summer. Our objectives were to determine 1) diel variation in diet composition and feeding periodicity for each species, and 2) examine interspecific diet overlap among the three species. Methods Sampling was carried out in Sterling Pond, a southcentral Lake Ontario embayment in Cayuga County, New York. Sterling Pond is a 42.5-ha embayment located at the confluence of Sterling Creek and Lake Ontario. Although Pumpkinseed, Golden Shiner, and Brook Silverside are the numerically dominant species, the fish community includes Brown Bullhead Ameiurus nebulosus, Largemouth Bass Micropterus salmoides, Northern Pike Esox lucius, Grass Pickerel E. americanus, and Yellow Perch Perca flavescens. The pond has a maximum depth of approximately 3 m and supports a diverse warm-water fish community. The shoreline is undeveloped and the substrate consists of sand and fine sediment with some rubble. Aquatic macrophytes were present in approximately 30% of the pond but were rare in the area sampled. We collected fishes with a 6.1-m bag seine (0.32-cm mesh) at 4-h intervals over a 24-h period in August We pulled the seine perpendicular to shore with each haul beginning at a depth of approximately 1.5 m. We conducted seining during each 4-h interval immediately adjacent to areas previously seined. Target sample size was 20 individuals of each species at each 4-h interval. We did not always meet this target, and in the case of Brook Silverside, we captured no individuals at 0400 h. Water temperatures ranged from 22.8 to 23.98C during the 24-h period. During the 24-h sampling period sunrise occurred at 0600 h and sunset at 2030 h. The moon was 11% illuminated and its phase was waning crescent. Mean air temperature was 20.68C and ranged from 15.6 to 25.68C. Atmospheric conditions were partly cloudy throughout the sampling effort. We considered samples collected at 1200 h and 1600 h diurnal, at 0800 h and 2000 h crepuscular, and at 2400 h and 0400 h nocturnal. Upon collection, we placed fish in 10% formalin. After 2 wk we transferred all fish to 70% ethyl alcohol. Prior to removing stomachs, we weighed all fishes to the nearest 0.01 g and measured them to the nearest mm total length. We quantified the entire stomach contents of Pumpkinseed and Brook Silverside. For Golden Shiner, which lacks a true stomach, we used only food in the anterior third of the intestinal tract for diet determination and feeding periodicity because this represented the most recent food ingested (Bowen 1996). We weighed the portion of the stomach or digestive tract that we excised (wet weight, nearest 0.1 mg) full and empty to determine feeding periodicity. We used ratios of the gut content weight to the total body weight for each 4-h period to determine feeding periodicity. We used feeding periodicity estimates for each 4-h interval to construct a 24-h diet for each species. We weighted diet composition at each 4-h interval by the feeding periodicity value for that period and then summed this value for all intervals for each taxon and divided by the number of feeding intervals. We examined diet information at 1200 h at the beginning and end of the study. The diet composition for each species was similar at each 1200-h period; therefore we combined it. However, we report feeding periodicity for each 1200-h period in order to represent closure over the 24-h period. We identified aquatic invertebrates to the lowest practical taxon (usually family), whereas we identified terrestrial invertebrates to order. We considered the larvae and pupa of some taxa (i.e., chironomids and tipulids) aquatic, whereas we considered adults of these taxa terrestrial. We derived dry weight estimates (1058C for 24 h) for all prey taxa to determine their relative contribution in the diet. Bootstrapping cluster analysis (McKenna 2003) compares multivariate diets based on a similarity index, and we used it to evaluate interspecific and intraspecific differences in the diet of fishes among 4-h intervals over the 24-h period. The cluster analysis objectively used the Bray Curtis similarity index, UPGMA linkage method, and 1,000 bootstrap samples to test for linkages among natural log-transformed diet at each 4-h interval. We arranged replicate samples by species diel period combination. Because the Shapiro Wilks test showed that diet data were not normally distributed, we assessed the significance of diet composition differences between each time period using the Kruskal Wallis 1-way analysis of variance (Statistix 10.0 Analytical Software, Tallahassee, Florida). We set a significance level of a ¼ 0.05 for all comparisons. Results We examined the diets of 444 fishes, including 170 young-of-year Pumpkinseed, 168 Golden Shiners, and 106 Brook Silversides (Table 1; TableS1, Supplemental Material). The 24-h diet of young-of-year Pumpkinseed was dominated by amphipods (41.4%), chironomids (34.9%), zooplankton (9.0%), and leeches (8.2%; Figure 1; Table S3, Supplemental Material). The zooplankton consumed consisted mainly of cladocerans (4.7%) and copepods (3.3%). Diel variation in diet composition of young-of-year Pumpkinseed occurred for both amphipods and chironomids. The contribution of amphipods in the diet ranged from 28.1% at 1600 h to 49.3% at 0800 h. Chironomids made up 18.7% of the diet at 0400 h and 43.9% at 0800 h (Figure 1). Golden Shiners had a diverse diet with six prey taxa contributing 8.8% of the 24-h diet. The diet of Golden Shiners consisted of tipulids (26.2%), chironomids (17.1%), zooplankton (16.1%), aquatic oligochaetes (12.0%), hydracarenids (8.9%), and amphipods (8.9%; Figure 1; Table S2, Supplemental Material). Ostracods (11.9%) were the primary zooplankton taxa consumed by Journal of Fish and Wildlife Management June 2017 Volume 8 Issue 1 241

3 Table 1. Number examined, mean size (total length [TL], [mm]), and size range of young-of-year Pumpkinseed Lepomis gibbosus, Golden Shiner Notemigonus crysoleucas, and Brook Silverside Labidesthes sicculus collected in August 2011 from Sterling Pond, Oswego County, New York. Pumpkinseed Golden Shiner Brook Silverside Time (h) No. examined Mean TL mm (range) No. examined Mean TL mm (range) No. examined Mean TL mm (range) (26 46) (36 48) (47 54) (20 41) (34 50) (41 58) (23 38) (35 56) (38 53) (24 42) (42 62) (47 55) (24 38) (30 55) (24 35) (35 56) (38 55) (21 32) (35 49) (38 47) Golden Shiners. Each of the major prey taxa of Golden Shiner exhibited diel variation in their contribution to the 24-h diet. The most extreme differences in diel contribution in the diet occurred for the two dominant prey taxa consumed by Golden Shiner. Tipulids contributed as little as 9.5% of the diet at 1200 h but as much as 77.8% at 0400 h, whereas chironomids were absent from the diet at 2000 h but contributed as much as 40.0% at 1600 h (Figure 1). The diet of Brook Silverside consisted mainly of terrestrial insects (58.5%), and was dominated by adult dipterans, adult culicids, and hymenopterans, which dominated the diet at each 4-h interval (Figure 1). Aquatic hemipterans (mainly dytiscids, notonectids, and gerrids), prey taxa that were rare in the diet of young-ofyear Pumpkinseed and Golden Shiner, were the secondranked prey of Brook Silverside (14.6%) in Sterling Pond. Aquatic invertebrates that would be expected to be consumed within the water column were largely absent from the diet of Brook Silverside. Chironomids, amphipods, and tipulids made up only 5.6%, 3.4%, and 2.3% of the 24-h diet of Brook Silverside. Two other aquatic ephemeropteran taxa, baetids (12.8%) and ephemerids (12.7%), were consumed at 2400 h (Figure 1). Cluster analysis showed clear distinction in the prey consumed by each species (Figure 2; Table S2, Supplemental Material). With the exception of Golden Shiner at 2000 h, intraspecific diet similarity among all 4-h time periods was greater than interspecific comparisons. Moreover, in all instances, interspecific diet similarity was significantly different (Table 2; Table S2, Supplemental Material). Over the 24-h period the diet of young-ofyear Pumpkinseed was similar at 0800 h and 1200 h and at 2000 h and 2400 h, whereas the diet of Brook Silverside was similar at 0800 h, 1600 h, and 2000 h. The diet of Golden Shiner was similar at 0800 h, 1200 h, and 2400 h (Figure 2). As mentioned previously, compared with other time periods, the diet of Golden Shiner was most dissimilar at 2000 h because of consumption of terrestrial invertebrates, hydracarinids, and gomphids. Young-of-year Pumpkinseed and Golden Shiner exhibited the most diel variation in feeding periodicity. Food consumption of young-of-year Pumpkinseed was greatest at 0800 h, 1600 h, and 2000 h and was significantly less at 0400 h, 1200 h, and 2400 h (Figure 3; Table S1, Supplemental Material). Conversely, Golden Shiner feeding periodicity was significantly greater at 0400 h, 1200 h, and 1600 h than at 0800 h, 2000 h, and 2400 h. Food consumption of Brook Silverside did not differ among time intervals but was slightly greater at 2000 h than at other time periods (Figure 3). The percentage of individuals with empty stomachs varied among species from 5% in Pumpkinseed, 29% in Brook Silverside, and 39% in Golden Shiner. The highest percentage of empty stomachs for each species was always associated with periods of less food consumption. Discussion Previous studies have found the summer diet of young-of-year Pumpkinseed to consist mainly of chironomids and zooplankton (Keast 1978; Rezsu and Specziár 2006). In Sterling Pond, amphipods were the primary prey consumed by young-of-year Pumpkinseed, which is consistent with observations on the diet of older age groups of Pumpkinseed that was carried out over all four seasons (García-Berthou and Moreno-Amich 2000). Studies examining the diel feeding ecology of Pumpkinseed are rare, with none that have targeted young-of-year fish. Declerck et al. (2002) observed little diel variation in the autumn diet composition of primarily Pumpkinseed, whereas Keast and Welsh (1968) and Collins and Hinch Table 2. Interspecific similarity values using the Bray Curtis similarity index between the diets of young-of-year Pumpkinseed Lepomis gibbosus, Golden Shiner Notemigonus crysoleucas, and Brook Silverside Labidesthes sicculus at 4-h intervals in August 2011 from Sterling Pond, New York. Values followed by an asterisk are significantly dissimilar. Time (h) Species Pumpkinseed Golden Shiner 0.267* 0.357* 0.242* 0.426* 0.444* 0.243* Pumpkinseed Brook Silverside 0.249* 0.208* 0.010* 0.261* 0.139* Golden Shiner Brook Silverside 0.264* 0.264* 0.049* 0.131* 0.135* Journal of Fish and Wildlife Management June 2017 Volume 8 Issue 1 242

4 Figure 1. Percent diet composition of young-of-year (A) Pumpkinseed Lepomis gibbosus, (B) Golden Shiner Notemigonus crysoleucas, and (C) Brook Silverside Labidesthes sicculus at 4-h intervals and over 24-h in Sterling Pond, New York, in August Journal of Fish and Wildlife Management June 2017 Volume 8 Issue 1 243

5 Figure 2. Dendrogram of cluster analysis results for young-of-year (PS) Pumpkinseed Lepomis gibbosus, (GS) Golden Shiner Notemigonus crysoleucas, and (BS) Brook Silverside Labidesthes sicculus at 4-h intervals in Sterling Pond, New York, August Bray Curtis similarity values are provided along the ordinate. A star (.) indicates a linkage between significant groups. (1993) concluded that Pumpkinseed were primarily diurnal foragers during summer. Our findings for young-of-year Pumpkinseed in Sterling Pond support diurnal feeding. However, in Sterling Pond Pumpkinseed also fed actively during crepuscular periods and exhibited substantial variation in diel diet composition. In Sterling Pond, Golden Shiners had the most diverse diet of the three species examined with six prey taxa contributing 8.8% of the diet. This contrasts with the findings of Divine (1968), who found that three or fewer prey taxa made up 90% of the diet of Golden Shiners. The diet of Golden Shiners in Sterling Pond also contrasted with the finding of previous researchers who reported that cladocerans were the primary prey taxa consumed (Pearse 1918; Keast and Webb 1966; Hall et al. 1979; Keast and Fox 1992). These same studies found that chironomids, terrestrial insects, and hydracarinids were also important in the diet of Golden Shiners. Prior to this study, only Cahn (1927) reported another taxa (amphipods) in addition to cladocerans that were the major dietary component of Golden Shiners. In fact, the major prey of Golden Shiners in Sterling Pond, tipulid larvae, is virtually absent in the reports of the diet of this species in other studies. Tipulids were consumed during each 4-h interval and their importance in the diet is most likely attributable to prey availability, which was not measured. Hall et al. (1979) reported that feeding activity of Golden Shiners was minimal at night, whereas Keast and Fox (1992) considered the species to be evening and night feeders. In Sterling Pond, Golden Shiners fed most heavily during diurnal periods and fed less during crepuscular and nocturnal periods. These observed differences in the feeding periodicity of Golden Shiners among studies could be related to prey availability (Hall et al. 1979) or predator avoidance (Helfman 1981). Golden Shiners exhibited more variation in feeding intensity within each 4-h feeding interval than did Pumpkinseed or Brook Silverside. Golden Shiners also had the highest percentage of empty stomachs (39%) among the three species. Even at 1200 h, when feeding periodicity of Golden Shiners was greatest, 30% of their stomachs were empty. Several studies have found zooplankton to be an important component in the diet of Brook Silverside (Ewers and Boesel 1935; Boesel 1937; Mullan et al. 1968; Strongin et al. 2011). However, Zimmerman (1970) reported limited consumption of zooplankton by Brook Silverside, which is similar to our observations in Sterling Pond. Also consistent with our observations, terrestrial invertebrates have previously been found to be important in the diet of Brook Silverside (Ewers and Boesel 1935; Boesel 1937; Mullan et al. 1968; Zimmerman 1970). We could find no diel feeding-ecology studies done previously on Brook Silverside. However, similar to our observations on diel feeding periodicity of Brook Silverside in Sterling Pond, Spraker and Austin (1997) reported that another athernoid species, Atlantic silverside Menidia menidia, fed continually over a 24-h period with greater consumption occurring during the day. The consistent differences in the diet of young-of-year Pumpkinseed, Golden Shiner, and Brook Silverside in Sterling Pond at all 4-h intervals was remarkable. At no Journal of Fish and Wildlife Management June 2017 Volume 8 Issue 1 244

6 Figure 3. Feeding periodicity estimates (6SE) of common young-of-year (A) Pumpkinseed Lepomis gibbosus, (B) Golden Shiner Notemigonus crysoleucas, and (C) Brook Silverside Labidesthes sicculus in Sterling Pond, New York, during August Different letters along the x-axis represent significant differences in feeding intensity between intervals. Journal of Fish and Wildlife Management June 2017 Volume 8 Issue 1 245

7 time was there a significant interspecific overlap in diet. In Sterling Pond, Brook Silverside were clearly surface feeders because their diet consisted mainly of terrestrial invertebrates and aquatic hemipterans, prey taxa that are found on the surface. Although young-of-year Pumpkinseed and Golden Shiner were feeding on benthic prey taxa, the relative contribution of these taxa in the diet was sufficiently different to create little overlap. Specifically, amphipods were the major prey of young-of-year Pumpkinseed but contributed little to the diet of Golden Shiner, whereas tipulids were the main prey of Golden Shiner but were absent from the diet of Pumpkinseed. Differences in prey use among these three species in Sterling Pond is likely due to interspecific variation in mouth and body form (Keast and Webb 1966), or feeding times (Keast and Welch 1968), which act to reduce competition (Keast 1965). Feeding periodicity among these three species broadly overlapped, so variation in mouth and body form may be more important in determining diet composition in similar lentic ecosystems where these species occur. Understanding the temporal feeding patterns of fishes is an important component of developing an understanding of interspecific associations within a fish community. The diel differences we observed in both feeding periodicity and diet composition in these three species in Sterling Pond may act to reduce competition for food resources. The fish community of Sterling Pond is typical of many small embayments contiguous to Lake Ontario, and perhaps other Great Lakes. Consequently, our observations on the summer diel-feeding ecology and interspecific feeding associations among these species may have application over a broader geographic area. Further studies, including examining the diel activity of potential predators such as esocids and largemouth bass would provide a more thorough understanding of fish community associations in Sterling Pond, as well as other Great Lakes embayments with similar fish communities. Moreover, because this study was carried out over a single 24-h period, further studies examining the diel feeding ecology of these species may be warranted. Supplemental Material Please note: The Journal of Fish and Wildlife Management is not responsible for the content or functionality of any supplemental material. Queries should be directed to the corresponding author for the article. Table S1. Number examined, mean total length (mm TL), and size range of young-of-year Pumpkinseed Lepomis gibbosus, Golden Shiner Notemigonus crysoleucas, and Brook Silverside Labidesthes sicculus collected from Sterling Pond, Oswego County, New York, during August JFWM-075.S1 (45 KB XLSX). Table S2. Interspecific similarity values between the diets of young-of-year Pumpkinseed Lepomis gibbosus, Golden Shiner Notemigonus crysoleucas, and Brook Silverside Labidesthes sicculus at 4-h intervals in Sterling Pond, Oswego County, New York during August Values followed by an asterisk are significantly dissimilar. JFWM-075.S2 (56 KB XLSX). Table S3. Percent diet composition of young-of-year Pumpkinseed Lepomis gibbosus, Golden Shiner Notemigonus crysoleucas, and Brook Silverside Labidesthes sicculus collected in August 2011 from Sterling Pond, Oswego County, New York. JFWM-075.S3 (66 KB XLSX). Reference S1. Bowen SH Quantitative description of the diet. Pages in Nielsen LA, Johnson DL, editors. Fisheries techniques. Bethesda, Maryland: American Fisheries Society. JFWM-075.S4 (12,139 KB PDF). Reference S2. Spraker H, Austin HM Diel feeding periodicity of Atlantic silverside (Menidia menidia), in the York River, Chesapeake Bay, Virginia. Journal of the Elisha Mitchell Scientific Society 113: JFWM-075.S5 (5,296 KB PDF). Acknowledgments Authorized by the Director, U.S. Geological Survey. We thank J. McKenna for advice on statistical analysis. We thank the Associate Editor and journal reviewers because their comments substantially improved the manuscript. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. References Beauchamp DA Seasonal and diel food habits of rainbow trout stocked as juveniles in Lake Washington. Transactions of the American Fisheries Society 119: Available: (1990)119,0475:SADFHO.2.3.CO;2 (September Boesel MW The food of nine species of fish from the western end of Lake Erie. Transactions of the American Fisheries Society 67: Available: org/ / (1937)67[215:tfonso]2.0.co;2 (September Bowen SH Quantitative description of the diet. Pages in Nielsen LA, Johnson DL, editors. Fisheries techniques. Bethesda, Maryland: American Fisheries Society. (see Supplemental Material, Reference S1, Found at JFWM-075.S4 (12,139 KB pdf). Journal of Fish and Wildlife Management June 2017 Volume 8 Issue 1 246

8 Cahn AR An ecological study of southern Wisconsin fishes. Illinois Biological Monographs 11. Available: handle/2142/25181/ecologicalstudyo11cahn.pdf? sequence¼1 (September Collins NC, Hinch SG Diel and seasonal variation in foraging activities of pumpkinseeds in an Ontario pond. Transactions of the American Fisheries Society 122: Available: (1993)122,0357:DASVIF.2.3.CO;2 (September Declerck S, Louette G, DeBie T, DeMeester L Patterns of diet overlap between populations of nonindigenous and native fishes in shallow ponds. Journal of Fish Biology 61: Available: onlinelibrary.wiley.com/doi/ /j tb02464.x/epdf (September Divine G A study of the smallmouth bass in ponds with special consideration of minnows and decapods as forage. Master s thesis. Columbia: University of Missouri. Available: xmlui/handle/10355/4915 (September Ewers LA, Boesel MW The food of some Buckeye Lake fishes. Transactions of the American Fisheries Society 65: Available: (1935)65[57:TFOSBL]2.0.CO;2 (September García-Berthou E, Moreno-Amich R Food of introduced pumpkinseed sunfish: ontogenetic diet shift and seasonal variation. Journal of Fish Biology 57: Available: doi/ /j tb00773.x/epdf (September Hall DI, Werner EE, Gilliam IF, Mittelbach GG, Howard D, Doner CG, Dickerman IA, Stewart AJ Diel foraging behavior and prey selection in the golden shiner (Notemigonus crysoleucas). Journal of the Fisheries Research Board of Canada 36: Available: /f (September Helfman GS Twilight activities and temporal structure in a freshwater fish community. Canadian Journal of Fisheries and Aquatic Sciences 38: Available: doi/abs/ /f81-187#.wd2anu27r5o (September Keast A Resource subdivision amongst cohabiting fish species in a bay, Lake Opinicon, Ontario. Pages in Proceedings, 8th Conference of the Great Lakes Research Division, University of Michigan, Ann Arbor. Available: (September Keast A Feeding interactions between age-groups of pumpkinseed (Lepomis gibbosus) and comparisons with bluegill (L. macrochirus). Journal of the Fisheries Research Board of Canada 35: Available: (September Keast A, Fox MG Space use and feeding patterns of an offshore fish assemblage in a shallow mesotrophic lake. Environmental Biology of Fishes 34(2): Available: %2FBF (September Keast A, Webb D Mouth and body form relative to feeding ecology in the fish fauna of a small lake, Lake Opinicon, Ontario. Journal of the Fisheries Research Board of Canada 23: Available: nrcresearchpress.com/doi/pdfplus/ /f (September Keast A, Welsh L Daily feeding periodicities, food uptake rates, and dietary changes with hour of day in some lake fishes. Journal of the Fisheries Research Board of Canada 25: Available: nrcresearchpress.com/doi/pdfplus/ /f (September McKenna JE Jr An enhanced cluster analysis program with bootstrap significance testing for ecological community analysis. Environmental Modelling and Software 18: Available: ftp://ftp.disi. unige.it/pub/person/rovettas/lab-inf-ii/ / articoli/ems-bootclus.pdf (September Mendelson J Feeding relationships among species of Notropis (Pisces: Cyprinidae) in a Wisconsin stream. Ecological Monographs 45: Available: (September Moyle PB Ecological segregation among three species of minnows (Cyprinidae) in a Minnesota Lake. Transactions of the American Fisheries Society 102: Available: (1973)102,794:ESATSO.2.0.CO;2 (September Mullan JW, Applegate RL, Rainwater WC Food of logperch (Percina caprodes), and brook silverside (Labidesthes sicculus), in a new and old Ozark reservoir. Transactions of the American Fisheries Society 97: Available: (September Pearse AS The food of the shore fishes of certain Wisconsin lakes. Bulletin of the United States Bureau of Fisheries 35: Available: google.com/books?hl¼en&lr¼&id¼hydoklfllfic&oi¼ fnd&pg¼pa249&dq¼theþfoodþofþtheþshoreþfishesþ ofþcertainþwisconsinþlakes.þ&ots¼yidvxs1uuf&sig¼ Q0Ufz_pQe4FOKKbgbbvDL5fu-HA#v¼onepage&q¼ The%20food%20of%20the%20shore%20fishes%20 of%20certain%20wisconsin%20lakes.&f¼false (September Railsback SF, Harvey BC, Hayse JW, LaGory KE Tests of theory for diel variation in salmonid feeding activity and habitat use. Ecology 86: Available: (September Reebs SG Plasticity of diel and circadian rhythms of fishes. Reviews in Fish Biology and Fisheries 12: Available: Journal of Fish and Wildlife Management June 2017 Volume 8 Issue 1 247

9 art%253a %252fa%253a pdf? originurl¼http%3a%2f%2flink.springer. com%2farticle%2f %2fa%3a & token2¼exp¼ ~acl¼%2fstatic%2fpdf% 2F684%2Fart%25253A %25252FA% 25253A pdf%3ForiginUrl%3Dhttp% 253A%252F%252Flink.springer.com%252Farticle% 252F %252FA%253A *~hmac¼ ff f45d020a45fbfbb1b2688b9b0 5b1fb339b0c22d508 (September Rezsu E, Specziár A Ontogenetic diet profiles and size-dependent diet partitioning of ruffe (Gymomcephalus cernuus), perch (Perca fluviatilis) and pumpkinseed (Lepomis gibbosus) in Lake Balaton. Ecology of Freshwater Fish 15: Available: researchgate.net/profile/andras_specziar/publication/ _Ontogenetic_diet_profiles_and_sizedependent_diet_partitioning_of_ruffe_ Gymnocephalus_cernuus_perch_Perca_fluviatilis_ and_pumpkinseed_lepomis_gibbosus_in_lake_ Balaton/links/54a66a400cf257a63608f2a4.pdf (September Spraker H, Austin HM Diel feeding periodicity of Atlantic silverside (Menidia menidia), in the York River, Chesapeake Bay, Virginia. Journal of the Elisha Mitchell Scientific Society 113: (see Supplemental Material, Reference S2, Found at DOI: org/ / jfwm-075.s5 (5,296 KB PDF). Strongin K, Taylor CM, Roberts ME, Neill WH, Gelwick F Food habits and dietary overlap of two silversides in the Tennessee Tombigbee waterway: the invasive (Menidia audens) versus the native (Labidesthes sicculus). The American Midland Naturalist 166: Available: (September Ward AJW, Webster MM, Hart PJB Intraspecific food competition in fishes. Fish and Fisheries 7: Available: profile/paul_hart6/publication/ _ Intraspecific_food_competition_in_fishes/links/ cf2d60c0e64c569.pdf (September Zimmerman CJ Growth and food of the brook silverside, (Labidesthes sicculus), in Indiana. Transactions of the American Fisheries Society 99: Available: (September Journal of Fish and Wildlife Management June 2017 Volume 8 Issue 1 248