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Table 3 Selectivity index (Ivlev) of prey in the diet of rainbow trout ( Oncorhynchus mykiss )

From: Selective foraging by non-native rainbow trout on invertebrates in Patagonian streams in Argentina

   Early autumn Late winter Late spring Late summer
Order Species NyF CVA NyF CVA NyF CVA NyF CVA
Oligochaeta Lumbriculidae sp.* −1 −1 −1 −1 −1 −1 −1 −1
Gasteropoda Chilina patagonica 0.11 0.91 −1 --- −1 0.95 −1 0.41
Biomphalaria peregrina --- --- --- --- --- --- 1 ---
Crustacea Hyalella araucana 0.75 --- 0.98 --- 0.31 --- 1 ---
Isopoda* --- 1 --- ---   --- --- ---
Araneae Arachnidae* --- --- 1 --- 1 --- --- ---
Cladocera Daphnia daphnia --- --- 1 --- --- --- --- ---
Plecoptera Aubertoperla illiesi --- 1 −0.30 0.71 --- −1 --- −1
Limnoperla jaffuelli −1 --- −0.20 −1 0.57 −1 --- ---
Antarctoperla michaelseni −1 0.12 --- −1 −1 −1 −1 0.76
Notoperlopsis femina −0.70 1 −1 --- --- --- −1 −1
Pelurgoperla personata --- 0.95 --- −1 --- −1 --- 0.93
Potamoperla myrmidon --- --- --- --- --- --- --- 1
Udamocercia arumífera --- --- --- --- --- −1 --- 1
Adult* --- --- --- --- 1 --- --- ---
Ephemeroptera Nousia crena 0.41 −1 --- −1 −1 −1 −1 0.85
Meridialaris chiloeensis 1 0.64 −1 0.73 1 --- --- −1
Meridialaris laminata −1 --- 1 --- −1 −1 --- ---
Penaphlebia chilensis −1 −1 −0.30 --- 0.74 −1 −1 1
Penaphlebia flavidula --- --- 1 --- --- --- --- ---
Penaphlebia (A)* --- --- --- --- 1 --- --- ---
Andesiops torrens 0.35 0.78 −1 --- −1 −1 0.34 0.03
Andesiops ardua −0.90 −1 −1 −1 1 −1 −1 −1
Ephemeroptera sp. 1 --- --- --- 1 --- --- ---
Parasericostoma ovale 0.38 0.96 −0.80 −1 −0.70 1 0.48 1
Trichoptera Hudsonema flaminii 0.50 0.72 1 −1 −1 −1 --- 0.89
Brachysetodes sp. −0.30 0.46 −1 −1 −1 0.14 −1 0.94
Triplectides sp. --- −1 1 --- --- −1 --- −1
Oxyethira bidentata 1 --- 1 --- −1 --- 1 ---
Neoatopsyche unispina −1 0.97 −1 −1 1 −1 −1 −1
Neoatopsyche brevispina −1 −1 −1 --- --- --- −1 0.14
Cailloma sp. 1 −1 −1 --- --- --- −1 0.93
Smicridea annulicornis 0.45 0.04 −1 0.90 0.53 0.90 −0.60 0.64
Smicridea frequens −1 −1 −1 --- --- --- −1 ---
Limnephilidae --- --- 1 --- --- --- --- ---
Adult* --- --- --- --- 1 --- --- ---
Stethelmis kaszabi 1 1 −1 --- −1 --- −1 1
Coleoptera Luchoelmis sp. −1 1 −1 −1 −1 −1 −1 −1
Elmidae (L) −1 −1 --- 1 −1 −1 −1 −1
Luchoelmis cekalovici −1 −1 −1 −1 −1 −1 −1 −1
Austrolimnius sp. −1 −1 −1 −1 --- −1 −1 −1
Rhantus signatus --- --- --- --- --- --- 1 ---
Tropisternus setiger --- --- --- --- --- --- 1 ---
Staphynilidae (A) * 1 --- --- --- --- --- --- ---
Nitidulidae (A) * --- --- --- --- 1 --- --- ---
Scirtidae (L) --- --- --- --- 1 --- --- ---
Coleoptera sp. * --- 1 0.32 1 --- --- --- ---
Athericidae (L) −1 0.57 0.45 1 −1 −1 −1 ---
Diptera Muscidae (L) --- 1 --- 1 1 --- --- ---
Simuliidae (L) −0.70 −0.20 −0.80 −0.30 1 −1 −1 −0.50
Empididae (L) −1 −1 −1 −1 −1 −1 −1 1
Paratrichocladius sp. −0.30 1 −1 −0.70 0.68 −1 −1 −1
Parapsectocladius sp. −1 --- --- --- −1 −1 −1 −1
Pseudochironomus sp. --- --- --- −1 −1 −1 −1 ---
Thienemanniella sp. 1 −1 --- −1 --- −1 −1 −1
Orthocladius sp. 1 --- −1 --- --- −1 --- ---
Lopescladius sp. --- −1 --- −1 --- 1 --- −1
Ceratopogonidae sp. --- --- −1 −1 −1 −1 --- −1
Pupae sp. 1     1    
Adult sp.* 1 1 1   1   1  
Odonata Cyanallagma interruptum --- --- 1 --- --- --- --- ---
Homoptera Homoptera sp.* 1 1      1  
Hymenoptera Hymenoptera sp.* 1       1 1
Orthoptera Orthoptera sp.*        1  
Hemiptera Hemiptera sp.* --- --- --- --- --- --- 1 ---
Fish fragment Eggs    1      
  1. From Nant y Fall (NyF) and Cabeza de Vaca (CVA) streams (Patagonia, Argentina) during the study period (early autumn, late winter, late spring of 2005, and late summer of 2006). Taxa absence at both environment and trout stomach were represented by --- and terrestrial prey (*).