BO, T

FENOGLIO, S

MALACARNE, G

PESSINO, M

English

Fenoglio, S

Bo, Tiziano

Malacarne, G

Institutional Research Information System University of Turin

 1   1 Feeding of Perla grandis nymphs (Plecoptera, Perlidae)  2 in an apennine first order stream (Rio Berga, NW Italy) 3  4  5  6  7 Stefano Fenoglio *, Tiziano Bo, Massimo Pessino and Giorgio Malacarne 8  9 University of Piemonte Orientale, Di.S.A.V., Via Bellini n. 25, 15100 Alessandria, Italy 10 * Corresponding author: fenoglio@unipmn.it 11  12  13 Running title:  14 Feeding of Perla grandis in an apennine stream 15  16  17  18  19  20 21  2  Abstract 21  22 Feeding habits of Perla grandis nymphs have been investigated in the Rio Berga, an 23 Apenninic stream of Northwestern Italy. In this study, we analysed gut contents of 50 nymphs 24 of this species, with the aim to investigate feeding preferences. Nymphs were collected from a 25 single riffle, whose benthic coenosis was also determined. We detected a change in the diet 26 during ontogenesis, with small instars feeding mainly on detritus and large instars strictly 27 carnivorous. We also detected the existence of an evident trophic selection: diet was almost 28 entirely dominated by Chironomidae, independently from their availability on the substratum. 29 This finding is discussed on the basis of ecological and ethological considerations. 30  31 Keywords: Perla grandis, gut contents, diet, Plecoptera, NW Italy 32  33  34  35 36  3  	36 The use of benthic invertebrates in biological monitoring has produced an evident increase in 37 the knowledge of taxonomy and systematic of these organisms (Merritt & Cummins 1996). 38 Unfortunately, the knowledge of great part of their ecology is still incomplete. In particular, 39 the analysis of the diet and the study of trophic ecology could represent important source of 40 data, that can be employed to improve our knowledge of the ecology of different species 41 (Elliott 2000), the structure of stream food webs (Huhta et al. 1999), and the functional 42 organization of lotic systems (Rosi-Marshall & Wallace 2002).   43 Plecoptera constitute a numerically and ecologically significant component in freshwater 44 ecosystem, mainly in running waters of all sizes, all over the world (Zwick 2004). For the 45 most part, larvae are either primarily carnivores (feeding largely upon other stream 46 invertebrates), as are many Systellognatha stoneflies and Euholognatha, or primarily leaf 47 shredders and detritivores, as are many Euholognatha (McCafferty 1998; Pattée et al. 2000). 48 Large sized stoneflies, such as Perlidae and Perlodidae, represent the main group of predators 49 in many  small, fishless lotic systems where they act as top-down control elements in the 50 benthic community (Wipfli & Gregovich 2002). Among this group, feeding seems to have 51 little or no importance in the adult life (Tierno de Figueroa & Sánchez-Ortega 1999; Tierno 52 de Figueroa & Fochetti 2001), because no solid food has been found in the gut of any perlid 53 or large perlodid species (Tierno de Figueroa & Fochetti 2001; Fenoglio & Tierno de 54 Figueroa 2003). Apparently, adults rely on the rich diet of the preimaginal stages (Fenoglio 55 2003).   56 Perla grandis (Rambur, 1841) (= P. maxima sensu Auctorum nec Scopoli, 1763) is a typical 57 rheophilous-mesothermal species. This species belonging to the Middle-Sud-European 58 chorological group and is widely distributed in the Apennines of northwestern Italy (Ravizza 59 1974; Ravizza & Ravizza Dematteis 1977; Ravizza Dematteis & Ravizza 1994).  60  4  The aim of our study was to investigate the diet of the nymphs of P. grandis in a fishless, first 61 order Apenninic stream, where this species constitutes the top predator taxon. 62  63 Material and Methods 64 In the days 09-10 January 2006, 50 P. grandis nymphs were collected in a 150 m uniform 65 riffle of the Berga stream (Carrega Ligure, High Borbera Valley, UTM 509.852 - 4.939.795; 66 780 m a.s.l, fig.1). In the sampling station, Rio Berga is a typical Apennine lotic environment, 67 characterized by elevate slope, coarse riverbed and fast-swallow flowing waters. Riparian 68 vegetation is mainly constituted by Quercus sp., Castanea sativa, Alnus glutinosa and some 69 specimens of Fagus sylvatica. In the upper Rio Berga catchment there are no anthropic 70 activities, so that this lotic system shows a good environmental quality, corresponding to an 71 environment without trace of human-inducted alteration (first class in the Italian Extended 72 Biotic Index, Ghetti 1997). Main environmental characteristics and abiotic parameters 73 (measured by Eijkelkamp 13.14 and 18.28 portable instruments) are reported in tab. 1. 74 Samplings were realized early in the morning, because Systellognatha are considered to be 75 chiefly nocturnal feeders (Vaught & Stewart 1974). Moreover, using a Surber net (20 x 20 76 cm; mesh 255 m), we collected 13 samples in the same reach to assess the presence and 77 abundance of the taxa of the natural benthic invertebrate population. Samples were preserved 78 in 90% ethanol. In the laboratory, all organisms were counted and identified to genus or 79 species level, except for: Lumbricidae, Lumbriculidae, Niphargidae and early instars of some 80 Diptera, which were identified to family or sub-family level. 81 Total length of P. grandis nymphs was measured (0.1 mm accuracy) and processed to assess 82 food consumption by means of gut content analysis. The most common method to measure 83 patterns of differential predation by aquatic insects is the examination of relative numbers of 84 prey remains in predator stomach contents, and the comparison of those numbers to prey 85  5  density estimated from samples from the predator’s habitat (Peckarsky 1984; Peckarsky & 86 Penton 1989).  87 To analyze the dimensional shift in food preference, we separately considered gut contents of 88 smaller nymphs (body length < 15.0 mm) and larger nymphs (body length > 15.0 mm). 89 During the analysis of small specimens, gut content of nymphs was studied using a 90 trasparency technique which has also been used to study feeding in imaginal stages (Fenoglio 91 & Tierno de Figueroa 2003). We use Hertwig’s liquid, a modification of Hoyer’s liquid, 92 which clears the body wall, thus allowing direct examination of the gut content without 93 dissection. To examine larger specimens we removed guts and the contents of the alimentary 94 canal were analysed by using the transparency method for slides. Fragments of animal prey 95 were identified to the lowest taxonomic level possible. Identification of prey was based on 96 sclerotized body parts, particularly head capsules, mouthparts and leg fragments. We also 97 differentiated four fractions: vegetable matter (diatoms, algae and fungi), animal matter, 98 unidentified organic matter (FPOM-fine particulate organic matter) and mineral matter (sand).  99 During the laboratory-phase of the study we use a NIKON SMZ 1500 light microscope (60-100 100 x) with JVC TK-C701EG videocamera. 101 To investigate the existence of feeding preferences, gut contents were compared with the 102 natural composition and abundance of macroinvertebrate communities in the riverbed using 103 the trophic electivity index of Ivlev (1961): 104 E = (ri-pi)/(ri+pi) 105 where ri = the proportion of ingested species and pi = the relative abundance in the benthic 106 community. The index ranges from −1.0 to 1.0. A value of −1.0 means total avoidance, 1.0 107 indicates preference and 0 indicates indifference. The presence of algae and detritus (e.g. 108 fragments of terrestrial vegetation) was recorded and quantified on a scale of 0-3 (0 = no 109 presence; 3 = the highest abundance class). 110  6   111 Results 112 We examined the gut contents of 50 Perla grandis nymphs; medium length of P. grandis 113 immature stages was 19.4 mm, with a minimum of 5.0 mm and a maximum of 27.2 mm. We 114 divided the nymphs in two dimensional classes: “small specimens” (n=13, total length < 15.0 115 mm) and “large specimens” (n=37, total length >15.0 mm).  116 In total we collected and identified 1115 aquatic invertebrates belonging to 38 taxa. 117 Taxonomical list and relative abundance are reported in tab. 2. Analysing the entire dataset, 118 we found that 6% of guts contained sand and that 12 % of guts were completely empty. 119 Considering the two dimensional classes, we detected an evident difference: smallest nymphs 120 showed a detritivorous diet (53.8 % of guts), with sporadic ingestions of midges and small 121 mayflies while largest ones are carnivorous, feeding on different invertebrate species (fig. 2). 122 In largest individuals we detected an evident trophic preference for Chironomidae. Midges 123 represented the most abundant item in the diet of P. grandis, with a relative importance that is 124 noticeably greater than their abundance in the substratum, and an high value of the Ivlev’s 125 electivity index (47.8 – fig. 3). Gut content analysis revealed that Chironomidae were ingested 126 also entire, without chewing: in facts, we found head capsules and fragments but also 13 127 complete larvae. Ephemeroptera Baetidae and Plecoptera Leuctridae, also if well represented 128 and abundant in the river bottom, were ingested with a minor frequency, such as 129 Ephemeroptera Heptageniidae, Leptophlebiidae and Trichoptera Hydropsychidae. Other 130 groups, also if well represented in the natural environment, were always avoided, such as 131 different families of Coleoptera (Hydraenidae and Dryopidae, for example) and Crustacea 132 Niphargidae. 133  134  135  7  Discussion 136 Many studies noticed that some predaceous stoneflies undergo changes in feeding pattern as 137 they grow, moving from a detritus based diet to a strictly carnivorous alimentation (Bo & 138 Fenoglio 2005). Our study confirms this findings, providing new data about the increase of 139 trophic spectrum during the ontogenesis of great Systellognatha nymphs. The increase in 140 number and type of preys is probably related not only to a dimensional increase of the 141 nymphs (and the related ability in to catch more prey types) but also to an increase in the 142 energetic demand in organisms that don’t feed in the adult stage and rely on the preimaginal 143 stages diet to perform gametogenesis.  144 Another interesting finding of this study is the evidence of clear trophic selection 145 mechanisms: Chironomidae, also if represented only a little component of the benthic 146 coenosis of Rio Berga, resulted the most present item in the food of P. grandis nymphs. The 147 importance of Chironomidae as food resource were also underlined in Neotropical 148 environments by Fenoglio (2003) in the genus Anacroneuria sp. (Perlidae), and in Neartic 149 environments in Acroneuria californica (Perlidae), as reported by Monakof 2003. This latter 150 species feed mainly on Chironomidae, various Ephemeroptera and Trichoptera, but electivity 151 index result positive only for midge larvae. 152 This result led to formulate the hypothesis that midges represent the preferred food item for 153 many Systellognatha: probably they offer a good combination of different elements, such as 154 mobility, dimensions and microhabitat overlap. 155  156 Acknowledgments 157 We thank Dr. G. Ferro for kind help in Hydraenidae determination and F. Bo for technical 158 support. We would also thank Dr. E. Guafa for continuous support and useful suggestions.  159  160  8  References 161 Bo T., Fenoglio S. 2005. Age-related shift in the diet of Perla marginata in a woodland 162 Apenninic creek (NW Italy) (Plecoptera: Perlidae). Entomologia Generalis 28: 147-154 . 163 Elliott J.M. 2000. Contrasting diel activity and feeding patterns of four species of 164 carnivorous stoneflies. Ecological Entomology 25: 26-34. 165 Fenoglio S. 2003. Feeding habits of Anacroneuria nymphs (Plecoptera Perlidae).Bollettino 166 della Società Entomologica Italiana 135: 15-17. 167 Fenoglio S., Tierno de Figueroa J.M. 2003. Observations on the adult feeding of some 168 Neoperla and Anacroneuria species (Plecoptera, Perlidae). African Entomology 11: 138-139 169 Ghetti P.F. 1997. Manuale di applicazione dell’Indice Biotico Esteso. Provincia Autonoma di 170 Trento, Trento, 222 p. 171 Huhta A., Muotka T., Juntunen A., Yrjonem M. 1999. Behavioural interaction in stream 172 food webs: the case of drift-feeding fish, predatory invertebrates and grazing mayflies. 173 Journal of. Animal Ecology 68: 917-927. 174 Ivlev V.S. 1961. Experimental ecology of the feeding of fishes. Yale University Press., New 175 Heaven.  176 McCafferty W.P. 1998. Aquatic Entomology. The fishermen’s and ecologists’ illustrated 177 guide to insects and their relatives. Jones and Barlett Publishers, 448 p. 178 Merritt R.W., Cummins K.W. 1996. An introduction to the aquatic insects of North 179 America. Kendall / Hunt. Dubuque, Iowa, 860 p. 180 Monakov A.K. 2003. Feeding of freshwater invertebrates. Kenobi Prod.Ghent, Belgium, 373 181 p. 182 Pattee E., Maamri A., Chergui H. 2000. Leaf litter processing and its agents in a temporary 183 Moroccan river. Verhandlungen Internationale Vereinigung für theoretische und angewandte 184 Limnologie 27: 3054-3057. 185  9  Peckarsky B.L. 1984. Predator-prey interactions among aquatic insects. P. 196-254 in: Resh 186 V.H., Rosenberg D.M. (ed.) Ecology of aquatic insects. Praeger, New York. 187 Peckarsky B.L., Penton M.A. 1989. Mechanisms of prey selection by stream-dwelling 188 stoneflies. Ecology 70: 1203-1218.  189 Ravizza C. 1974. Ricerche ecologico-faunistiche sui Plecotteri della Val Staffora (Appennino 190 Lombardo). Bollettino del Museo Civico di Storia Naturale di Verona 1: 195-248. 191 Ravizza C., Ravizza Dematteis E. 1977. La plecotterofauna dell’alta valle del Tanaro (Alpi 192 Liguri). Memorie della Società Entomologica Italiana 55: 183-215. 193 Ravizza Dematteis E., Ravizza C. 1994. Altitudinal zonation and coenotic patterns of 194 Plecoptera in a northern apennine stream. Bollettino della Società Entomologica Italiana 126: 195 51-60. 196 Rosi-Marshall E.J., Wallace J.B. 2002. Invertebrate food webs along a stream resource 197 gradient. Freshwater Biology 47: 129-141. 198 Tierno de Figueroa J.M., Sanchez-Ortega A. 1999. Imaginal feeding of certain 199 systellognathan stonefly species (Insecta, Plecoptera).  Annales of the Entomological Society 200 of America 92: 218–221. 201 Tierno de Figueroa J.M ., Fochetti R. 2001. On the adult feeding of several European 202 stoneflies (Plecoptera). Entomological News 112: 130–134. 203 Vaught G.L., Stewart K.W. 1974. The life history and ecology of the stonefly Neoperla 204 clymene (Newman) (Plecoptera: Perlidae). Annales of the Entomological Society of America 205 67: 167–178. 206 Wipfli M.S., Gregovich D.P. 2002. Export of invertebrates and detritus from fishless 207 headwater streams in southeastern Alaska: implications for downstream salmonid 208 production. Freshwater Biology 47: 957-969. 209  10  Zwick P. 2004. Key to the west Palaearctic genera of stoneflies (Plecoptera) in the larval 210 stage. Limnologica 34: 315-348. 211 212  11  Table 1: Some environmental characteristics and abiotic parameters of stream reach during 212 field sampling 213  214 __________________________________________ 215 Stream order    1th 216 Altitude (m asl)   800 217 Width (cm)    170 ± 20 218 Depth (cm)    15 ± 5  219 Water temperature (°C)  3.8 ± 0.5 220 Air Temperature (°C)   - 2.0 ± 1.0 221 pH     7.9 222 Conductivity (µS/cm)  25.0 223 O2 (mg/l)    102.0 224 __________________________________________ 225  226  227  228 229  12  Table 2: Percent relative abundance (% value in the community) for macroinvertebrates 229 collected in the natural riverbed in the Rio Berga (NW Italy).  230 __________________________________________________________________________ 231  232 Taxa  relative  233   abundance % FFG* 234 __________________________________________________________________________ 235 Plecoptera    236 Perlidae Perla grandis 4,48 P 237  Perla marginata 0,90 P 238  Dinocras cephalotes 3,41 P 239 Perlodidae Isoperla sp. 7,00 P 240 Leuctridae Leuctra sp. 14,53 Sh 241 Nemouridae Nemoura sp. 8,70 Sh 242  Protonemura sp. 0,18 Sh 243  Amphinemura sp. 1,35 Sh 244 Chloroperlidae Chloroperla sp. 1,08 P 245 Taeniopterygidae Brachyptera sp. 1,88 Sh 246 Ephemeroptera    247 Heptageniidae Ecdyonurus sp. 7,62 Sc 248  Rhithrogena sp. 6,46 Sc 249  Epeorus sylvicola 2,06 Sc 250 Baetidae Baetis sp. 15,61 Cg 251 Ephemerellidae Torleya major 0,54 Cg 252 Leptophlebiidae Habroleptoides sp. 5,20 Cg 253 Trichoptera    254 Hydropsychidae Hydropsyche sp. 7,09 F 255 Philopotamidae Philopotamus sp. 0,18 F 256 Rhyacophilidae Rhyacophila sp. 0,72 P 257 Sericostomatidae Sericostoma sp. 0,27 Sh 258 Odontoceridae Odontocerum albicorne 0,09 Sh 259 Limnephilidae Potamophylax cingulatus 1,70 Sh 260  Undet. 0,18 Sh 261 Diptera    262 Chironomidae Tanypodinae 0,36 P 263  Chironominae 1,43 Cg 264 Tipulidae Tipula sp. 1,08 Sh 265 Athericidae Atherix sp. 1,61 P 266 Empididae Emerodrominae 0,09 P 267 Limoniidae  0,18 P 268 Coleoptera    269 Hydraenidae Haenydra devillei 0,54 Sc 270 Helodidae (larvae)  0,18 Sh 271 Dryopidae Helichus substriatum 0,09 Sh 272 Crustacea    273 Niphargidae  1,61 Cg 274 Annellidae    275 Erpobdellidae Dina lineata 0,45 P 276 Lumbriculidae  0,54  277 Lumbricidae  0,09  278 Lumbricidae Eiseniella tetraedra 0,36 Cg 279 Arachnida    280 Hydracarina  0,18 P 281 __________________________________________________________________________ 282  283 (*) FFG: functional feeding groups (Cg=collectors-gatherers; F=filterers; P=predators; Sc=scrapers; 284 Sh=shredders. See Merritt and Cummins, 1996). 285  13  Fig. 1: Rio Berga and sampling station. 286  287  288  289  290  291  292  293  294  295  296  297  298  299  300  14  Fig. 2: Relative abundance of prey items in the Perla grandis nymphs.  301  302  303 ChironomidaeEpeorusEcdyonurusHabroleptoidesBaetis LeuctraPlecopteraNemouraDipteraRhithrogenaEphemeropteraHydropsychidaeTrichoptera 304 305  15  Fig. 3: Electivity index (E*) for the macroinvertebrate taxa in the guts of the three size groups 305 of Perla grandis nymphs.  306  307  308  309 Electivity Index (E*)-1,00 -0,75 -0,50 -0,25 0,00 0,25 0,50 0,75 1,00PlecopteraNemouraLeuctraBaetis HabroleptoidesEcdyonurusEpeorusRhithrogenaEphemeropteraHydropsychidaeTrichopteraChironomidaeDiptera 310 

Feeding of Perla grandis nymphs (Plecoptera : Perlidae) in an apennine first order stream (Rio Berga, NW italy)

https://iris.unito.it/bitstream/2318/1728547/1/ASEF_Fenoglio_Perla_2006.pdf

Feeding of Perla grandis nymphs (Plecoptera : Perlidae) in an apennine first order stream (Rio Berga, NW italy)

Abstract

Similar works

Full text

Available Versions

Institutional Research Information System University of Turin