COMPARATIVE ANALYSES OF THE FOOD SPECTRA OF THE FISH

Analele Ştiinţifice ale Universităţii „AL. I. CUZA” Iaşi, s. Biologie animală, Tom LII, 2006

COMPARATIVE ANALYSES OF THE FOOD SPECTRA OF THE

FISH POPULATIONS LIVING IN THE RIVERS OITUZ AND CASIN

MIRCEA NICOARĂ1, DOREL URECHE2, GABRIEL PLĂVAN1 and

MIHAI ERHAN1 1 “Al. I. Cuza” University Iaşi, Faculty of Biology, Bd. Carol I 20A, 700505 Iaşi, Romania;

e-mail: [email protected] 2 University of Bacău, Faculty of Science, Str. Mărăşeşti 157, 600115 Bacău, Romania;

e-mail: [email protected]

Abstract. Food spectra of the four fish species common for the basins Oituz and Casin, respectively: Alburnoides bipunctatus (chub), Barbus petenyi (mediterranean barbel), Orthrias barbatulus (stone loach) and Phoxinus phoxinus (Eurasian minnow), were compared. Fish were sampled in 1998, 1999 and 2004. Comparison made regarded both fish food composition and food behaviour. Keywords: fish, food spectrum, River Oituz, River Casin Rezumat. Analiza comparativă a spectrelor trofice ale speciilor de peşti care populează râurile Oituz şi Caşin. Au fost comparate spectrele trofice ale celor patru specii de peşti comune bazinelor râurilor Oituz şi Caşin, respectiv: Alburnoides bipunctatus (beldiţă), Barbus petenyi (moioagă), Orthrias barbatulus (grindel) şi Phoxinus phoxinus (boiştean). Pescuitul s-a făcut în anii 1998, 1999 şi 2004. Analiza comparativă a avut în vedere atât compoziţia hranei speciilor de peşti, cât şi comportamentul alimentar al acestora. Cuvinte cheie: peşti, spectrul trofic, râurile Oituz şi Caşin

Introduction The goal of the study was a compared analysis of the food spectra in fish

populations living in River Casin and in its tributaries (Curita and Bucium brooks), respectively in River Oituz and in its tributaries (Halos, Lesuntu Mare), as well as in Lesuntu Mic and Slatina – tributaries of the river Lesuntu Mare.

Food composition and food behaviour of the fish species captured were compared. Fishing occurred in 1998, 1999 and in 2004. Fish species captured were: Salmo fario, Cottus gobio, Alburnoides bipunctatus, Alburnus alburnus, Gobio obtusirostris, Barbus petenyi, Phoxinus phoxinus, Pseudorasbora parva, Squalius cephalus, Orthrias barbatulus and Sabanejewia aurata balcanica.

Material and Methods Food spectra of the fish species common in the two basins (Oituz and Casin):

Alburnoides bipunctatus (chub), Barbus petenyi (mediterranean barbel), Orthrias barbatulus (stone loach) and Phoxinus phoxinus (Eurasian minnow) were studied, checking how the food spectra of these species varies from one basin to another, according to the particular food offer. Environmental food offer was established based upon the analyses of the stomach content of all specimens captured, by the means of a stereomicroscope. A qualitative analysis was performed, trying to identify till the lowest taxa possible the invertebrates existing in the stomach content of each individual, while the different prey categories were quantified. Results were statistically processed, using a range of ecological indices.

The relative abundance was calculated using the formula:

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Mircea Nicoară et al.

Ra = No. of individuals of the species A / total no. of individuals x 100 The ecological similitude coefficient (Sörensen coefficient -Ss) was calculated

using the formula: Ss = 2 x No. of species common in samples A and B / No. of species in sample A + No. of species in

sample B.

This coefficient has values between 0 and 1. According to the presence / absence of the species, this indicator shows the degree of similitude between the two samples / communities / biocoenoses etc.

Ivlev electivity index (Ivlev, 1961) was calculated according to the formula: Ei = ri – ni / ri + ni where: ri – percentage of certain species in the consumer’s diet (relative abundance) ni – percentage of the same species from the total resources (relative abundance).

Index positive and close to 1 values show the preference while values between 0

and -1 show the avoiding of the respective resource. Results and Discussion

Environmental food offer is given by the preys identified in the stomach content of all specimens belonging to the 11 fish species present in the captures. A total number of 47 prey species and groups were found in the fish stomachs as suits: 34 types in the fish specimens captured from River Casin while 33 taxa in River Oituz (Table 1).

Twenty prey types were common for the two rivers. Dominant were families Baetidae (Insecta, Ephemeroptera) and Chironomidae (Insecta, Diptera) with different percentages in the two basins. Simuliidae (Insecta, Diptera) and Trichoptera specimens were also well represented.

Table 1. Food offer (macroinvertebrates) in the rivers Casin and Oituz (l = larvae; n = nymphs).

Casin Oituz

No.

Preys No. of

individuals Relative

abundance (%) No. of

individuals Relative

abundance (%) 1. Araneida 5 0.36

2. Antocha sp. 8 0.59

3. Baetidae 385 19.53 794 58.90

4. Bezzia sp. 1 0.05

5. Brachycera (n) 4 0.20

6. Carabidae 1 0.05 1 0.07

7. Chironomidae 1024 51.95 193 14.31

8. Chironomus tricolor 10 0.50

9. Coleoptera 5 0.25 18 1.33

10. Coleoptera (Staphylinidae) 1 0.05

11. Dicranota sp. 1 0.05

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12. Diptera adults 1 0.07

13. Diptera adults (Brachycera) 1 0.05 3 0.22

14. Diptera (Nematocera) 2 0.10 2 0.14

15. Diptera (Nematocera - n) 3 0.15

16. Diptera (n) 20 1.01

17. Dixa sp. (Dixidae) 1 0.07

18. Ecdyonurus sp. (Heptageniidae)

6 0.30 31 2.29

19. Limnius sp.(Elmidae) 1 0.05 4 0.29

20. Elmis sp. 20 1.01 7 0.51

21. Ephemeroptera 37 1.87 19 1.40

22. Ephemeroptera (n) 7 0.35

23. Caenis sp. (Ephemeroptera) 2 0.10

24. Forficula auricularia (Dermaptera)

1 0.07

25. Formicidae 49 2.48 19 1.40

26. Gammaridae 1 0.05 2 0.14

27. Heteroptera 2 0.14

28. Hydraena sp. 1 0.05

29. Hymenoptera 3 0.22

30. Insecta (l) 3 0.15 1 0.07

31. Insecta (n) 50 2.53 6 0.44

32. Insecta unidentified 6 0.30 11 0.81

33. Isogenus sp. (Plecoptera) 11 0.81

34. Lepidoptera (l) 4 0.29

35. Unidentified 4 0.20 9 0.66

36. Nematoda 21 1.06 1 0.07

37. Odonata (Platycnemis sp.) 1 0.05

38. Oligochaeta 6 0.30 9 0.66

39. Orthoptera 1 0.07

40. Perla sp. 2 0.14

41. Platambus sp. (Dytiscidae) 1 0.07

42. Plecoptera 1 0.07

43. Simuliidae 191 9.69 49 3.63

44. Siphlonurus sp. 5 0.25

45. Tanypus sp. 10 0.50

46. Trichoptera 89 4.51 128 9.49

47. Trichoptera (n) 3 0.15

Total 1971 100 1348 100

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In the 4 fish species, common for the two rivers, a total number of 21 prey species and groups were found. 12 types of preys were found in the stomachs of Alburnoides bipunctatus; 12 taxa were found in the stomachs of Barbus petenyi; 11 taxa were found in the stomachs of Orthrias barbatulus; 14 taxa were found in the stomachs of Phoxinus phoxinus in River Casin (Table 2).

Table 2. Digestive content of the four fish species compared, in River Casin (l = larvae; n = nymphs).

Fish species

Alburnoides bipunctatus

Barbus petenyi Orthrias barbatulus

Phoxinus phoxinus

Preys

No. % No. % No. % No. % Baetidae 19 20.21 123 18.75 214 35.19 18 15.78 Brachicera (n) 4 0.65 Chironomidae 19 20.21 290 44.20 345 56.74 Chironomus tricolor 3 0.49 4 3.50 Coleoptera (Staphylinidae)

1 0.87

Coleoptera 2 2.12 Dicranota sp. 1 0.87 Diptera (n) 1 0.15 15 2.46 Ecdyonurus sp. 5 5.31 2 0.30 Ephemeroptera 1 1.06 5 0.76 5 0.82 22 19.29 Ephemeroptera (n) 7 7.44 Elmis sp. 12 1.82 7 6.14 Formicidae 7 7.44 6 5.26 Hydraena sp. 1 0.87 Insecta (l) 2 2.12 1 0.15 Insecta (n) 12 12.76 6 0.91 1 0.16 18 15.78 Insecta indeterminate 2 2.12 4 3.50 Indeterminate 1 0.16 Nematoda 6 0.91 Odonata – Platycnemis sp.

1 1.06

Oligochaeta 6 5.26 Simuliidae 179 27.28 Siphlonurus sp. 2 0.30 2 0.32 Tanypus sp. 9 1.48 1 0.87 Trichoptera 17 18.08 29 4.42 9 1.48 22 19.29 Trichoptera (n) 3 2.63

Total 94 100 656 100 608 100 114 100

A total number of also 21 prey species and groups were found in River Oituz in the 4 common fish species. 9 types of preys were found in the stomachs of Alburnoides bipunctatus; 10 taxa were found in the stomachs of Barbus petenyi; 10 taxa were found in the stomachs of Orthrias barbatulus; 19 taxa were found in the stomachs of Phoxinus phoxinus (Table 3).

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Table 3. Digestive content of the four fish species compared, in River Oituz (l = larvae; n = nymphs).

Fish species


Barbus petenyi Orthrias barbatulus

Phoxinus phoxinus

Preys

No. % No. % No. % No. % Antocha sp. 4 1.96 1 0.33 Araneida 1 0.33 Baetidae 8 8.79 36 34.95 141 69.11 160 53.33 Chironomidae 50 54.94 27 26.21 20 9.8 51 17 Coleoptera 1 1.09 4 3.88 7 2.33 Ecdyonurus sp. 3 2.91 4 1.96 11 3.66 Ephemeroptera 14 15.38 1 0.97 4 1.33 Elmidae (Limnius sp.) 2 0.66 Elmis sp. 3 2.91 3 1 Forficula auricularia (Dermaptera)

1 0.33

Formicidae 3 3.29 1 0.97 5 1.66 Gammaridae 1 0.49 1 0.33 Insecta (l) 1 0.49 Insecta (n) 5 5.49 1 0.33 Insecta unidentified 3 1 Isogenus sp. 2 0.98 Unidentified 1 1.09 5 1.66 Oligochaeta 1 0.97 1 0.49 3 1 Plecoptera 1 0.33 Simuliidae 1 1.09 3 2.91 18 8.82 8 2.66 Trichoptera 8 8.79 24 23.3 12 5.88 32 10.66

Total 91 100 103 100 204 100 300 100

The highest values of the ecological similitude coefficient (Ss) were recorded for the species Alburnoides bipunctatus and Barbus petenyi, revealing a similar feeding no matter the host river, while the lowest value - 0.28 characterized Orthrias barbatulus (Table 4) showing important differences in the feeding of this last species, related to the water body.

Table 4. Values of the ecological similitude coefficient (Ss) for the rivers Casin and Oituz.

Species Ecological similitarity coefficient Alburnoides bipunctatus 0.66

Barbus petenyi 0.63 Orthrias barbatulus 0.28 Phoxinus phoxinus 0.48

Alburnoides bipunctatus showed a differentiated feeding way according to the

host river, preferring a prey type in one river, while avoiding it in the other. Barbus petenyi constantly rejected Baetidae and preferred Elmis sp. Orthrias barbatulus showed a constant feeding preference for Baetidae and avoided Trichoptera. Phoxinus phoxinus, with a larger range of prey types in both rivers, constantly preferred Elmis sp., Oligochaeta and Trichoptera while rejected Baetidae (Table 5).

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Table 5. Values of Ivlev electivity index for rivers Casin and Oituz (l = larvae; n = nymphs).

Fish species


Barbus petenyi Orthrias barbatulus Phoxinus phoxinus

Preys

Casin Oituz Casin Oituz Casin Oituz Casin Oituz Antocha sp. 0.53 - 0.28 Araneida 0.65 Baetidae 0.01 - 0.74 -0.02 - 0.25 0.28 0.07 -0.10 - 0.04 Brachicera (n) 0.52 Chironomidae -0.43 0.58 -0.08 0.29 0.04 - 0.18 0.08 Chironomus tricolor -0.01 0.75 Coleoptera (Staphylinidae)

0.89

Coleoptera 0.78 - 0.09 0.48 0.27 Dicranota sp. 0.89 Diptera (n) -0.74 0.41 Ecdyonurus sp. 0.89 0 0.11 - 0.07 0.23 Ephemeroptera -0.27 0.83 -0.42 0.31 -0.39 0.82 - 0.02 Ephemeroptera (n) 0.91 Elmidae (Limnius sp.) 0.38 Elmis sp. 0.28 0.35 0.71 0.32 Forficula auricularia (Dermaptera)

0.65

Formicidae 0.5 0.40 - 0.18 0.35 0.08 Gammaridae 0.55 0.40 Hydraena sp. 0.89 Insecta (l) 0.86 0 0.75 Insecta (n) 0.85 - 0.14 Insecta Unidetified 0.75 0.84 0.10 Isogenus sp. (Plecoptera)

0.09

Unidentified 0.24 -0.11 0.43 Nematoda -0.07 Odonata – Platycnemis sp.

0.90

Oligochaeta 0.19 - 0.14 0.89 0.20 Plecoptera 0.65 Simuliidae - 0.53 0.47 - 0.11 0.41 - 0.15 Siphlonurus sp. 0.09 0.12 Tanypus sp. 0.49 0.27 Trichoptera 0.60 - 0.03 -0.01 0.42 -0.50 - 0.23 0.62 0.05 Trichoptera (n) 0.89

Conclusions Environmental food offer, given by the preys identified in the stomachs of all

fish specimens, consisted of 47 prey types: 34 types for River Casin, while 33 taxa for River Oituz. A total number of 21 prey species and groups were found in the 4 common fish species in both rivers.

Twelve types of preys were found in Alburnoides bipunctatus, 12 taxa in Barbus petenyi, 11 taxa in Orthrias barbatulus, and 14 taxa in Phoxinus phoxinus in River Casin.

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Nine types of preys were found in Alburnoides bipunctatus; 10 taxa in Barbus petenyi; 10 taxa in Orthrias barbatulus, and 19 taxa in Phoxinus phoxinus in River Oituz.

Alburnoides bipunctatus and Barbus petenyi revealed a similar feeding in the two rivers, while Orthrias barbatulus showed important differences in feeding related to the water body. Most paradoxical feeding way characterized the species Alburnoides bipunctatus that preferred a prey type in one river and avoided it in the other. Barbus petenyi and Orthrias barbatulus showed a more constant preference/rejection for certain prey types, while Phoxinus phoxinus had the largest food niche in both rivers, constantly preferring/rejecting certain prey types.

References Bănărescu, P., 1964. Fauna R.P.R., Pisces-Osteichthyes, XIII. Ed. Academiei R.P.R., Bucuresti. Du Chatenet, G., 1990. Guide des coléoptères d’Europe. Delachaux & Niestle, Paris. Hurlbert, S. H., 1978. The measurement of niche overleap and some relatives. Ecology, 59(1): 67-77. Magurran, A. E., 1988. Ecological Diversity and its Measurement. Croom Helm, London. Tachet, H., Bournaud, M. & Richoux, Ph., 2001. Introduction a l'étude des macroinvertebres des eaux douces.

Ed. Univ. Lyon. Tachet, H., Richoux, Ph., Bournaud, M. & Usseglio-Polatera, Ph., 2001. Invertébrés d’eaux douce. Systématique,

biologie, écologie. Ed. CNRS, Paris. Ureche, D., Battes, K.W., Pricope, F. & Stoica, I., 2004. Prospective monitoring of fish communities from Buzau

River’s basin. Analele Ştiinţifice ale Universităţii “Al. I. Cuza” Iaşi, s. Biologie Animală, L: 229-242.

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COMPARATIVE ANALYSES OF THE FOOD SPECTRA OF THE FISH