**3. Results**

 μ<sup>3</sup> ),

> μ<sup>3</sup> )

*quadrangularis, Alona guttata, Coronatella rectangula, Pleuroxus aduncus* and Nauplii (5.0 × 107

), *Daphnia cucullata* (1.0 × 108

classes according to fork length (FL) measuring 6.0–6.9 cm, 7.0–7.9 cm, 8.0–8.9 cm, 9.0–9.9 cm, 10.0–10.9 cm and 11.0–11.9 cm. Fish weight were classified into four groups: ≤5.0 g, 5.1–9.9 g,

the fish. Percentage and frequency of occurrence were used to estimate the dietary importance of each prey category [52, 53]. The percentage of the relative importance index [54] and three-dimensional graphical representations [55] were used to express prey importance.

uate the variety of foods in stomach. This index provides a general indication of changes in species diversity [56]. In the first step of statistical analysis, the normality of data was tested for each parameter using the Shapiro-Wilk test, and it was shown that dataset was

μ<sup>3</sup>

). All topmouth gudgeon caught were divided into six size

are the total net weight and number of prey and

), *Gomphonema* sp., (6.0x104

)\*10,000 [51]. Where,

) were used to eval-

is the weight of

μ<sup>3</sup>

**Figure 1.** Location of the Lake Eğirdir and sampling sites.

%, where W<sup>i</sup>

μ<sup>3</sup>

Feeding intensity (stomach fullness) was estimated by I<sup>F</sup> = (WSC/W<sup>F</sup>

is the fullness index, WSC is the weight of the stomach contents and W<sup>F</sup>

and N<sup>i</sup>

is the number of stomachs containing prey i. Shannon-Weaver (H′

*Bosmina longirostris* (4.0 × 107

and *Pediastrum* sp. (8.0 × 103

10.0–14.9 g and ≥15.0 g.

360 Selected Studies in Biodiversity

% + W<sup>i</sup>

%) \* O<sup>i</sup>

IF

Oi

IRI<sup>i</sup> = (N<sup>i</sup>

#### **3.1. The size and weight ranges of topmouth gudgeon**

In this study, topmouth gudgeon ranged from 6.1 to 11.1 cm in fork length (FL) with an average value of 7.71 ± 0.18 cm and their total weight ranged from 3.52 g to 25.49 g, with an average value of 8.13 ± 0.78 g. The number of species, minimum and maximum fork length and minimum and maximum weights from different months in the lake are presented in **Table 1**.


**Table 1.** Number of the fish caught during the study, their minimum, maximum and average fork length and minimum, maximum and average weight.

#### **3.2. The diet composition of topmouth gudgeon**

The diet of topmouth gudgeon in the lake was found to consist of phytoplankton, zooplankton, Insecta, Malacostraca, Annelida and unidentified eggs (**Table 2**).

HSD, p < 0.05). In addition, Tukey-Kramer HSD showed a significant difference between the length group of 6.0–6.9 cm and 7.0–7.9 cm together with 8.0–8.9 cm (p < 0.05). The longer groups (*P.parva*) in whose stomach contents *N. hibernica* was not recorded were not significantly dif-

Prey Selection of *Pseudorasbora parva* (Temminck and Schlegel, 1846) in a Freshwater Ecosystem (Lake Eğirdir/Turkey)

*Alona guttata* 54 3.78 15 16.85 0.0027 0.0318 64.31 0.985 *Alona quadrangularis* 14 0.98 8 8.99 0.0007 0.0082 8.89 0.136 *Coronatella rectangula* 6 0.42 4 4.49 0.0003 0.0035 1.91 0.029 *Daphnia cucullata* 13 0.91 1 1.12 0.0013 0.0153 1.04 0.016 *Disparalona rostrata* 2 0.14 1 1.12 0.0001 0.0012 0.16 0.002 *Graptoleberis testudinaria* 32 2.24 14 15.73 0.0016 0.0188 35.57 0.545 *Pleuroxus aduncus* 2 0.14 1 1.12 0.0001 0.0012 0.16 0.002 *Bosmina longirostris* 17 1.19 4 4.49 0.0006 0.0080 5.39 0.083 *Chydorus sphaericus* 43 3.01 16 17.98 0.0004 0.0050 54.26 0.831 *Mesocyclops leuckarti* 3 0.21 2 2.25 0.0000 0.0004 0.47 0.007 *Nitocra hibernica* 480 33.64 30 33.71 0.0048 0.0565 1135.74 17.397 Nauplii 1 0.07 1 1.12 0.0000 0.0000 0.08 0.001

*Trichoptera* larvae 7 0.49 7 7.87 0.6200 7.3020 61.29 0.939 *Chironomus* sp. 616 43.17 39 43.82 4.0260 47.4161 3969.39 60.801 *Chironomus* (pupa) 37 2.59 12 13.48 1.0020 11.8010 194.07 2.973

*curvispinum* 63 4.41 28 31.46 2.2300 26.2638 965.17 14.784

Annelid 15 1.05 3 3.37 0.6000 7.0664 27.36 0.419

*Gomphonema* sp. 19 1.33 2 2.25 0.0000 0.0000 2.99 0.046 *Pediastrum* sp. 2 0.14 1 1.12 0.0000 0.0000 0.16 0.002

 Unidentified egg 1 0.07 1 1.12 0.0000 0.0005 0.08 0.001 **Total** 1427 100 190 8.49 100 6528.51 100

N, prey number; W, prey weight; O, frequency of occurrence and IRI, Relative Importance Index.

**Table 2.** Diet composition of topmouth gudgeon in Lake Eğirdir between 2010 and 2011.

**N %N O %O W %W IRI %IRI**

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363

ferentiated than length group of 6.0–6.9 cm.

**Zooplankton taxa**

**Insecta**

**Malacostraca** *Chelicorophium* 

**Annelida**

Phytoplankton

Unidentified

Total weight of 1427 prey items was 8.49 g. Insects were the most frequently ingested prey with 66.52% by weight. *Chironomus* sp. (47.42%) was the dominant prey insects followed by *Chelicorophium curvispinum* (26.26%) and *Chironomus* pupa (11.80%) in terms of weight. Relative Importance Index (IRI) showed that prey Insecta (64.71%) had more importance than the zooplankton prey categories (20.03%) and *C. curvispinum* (14.78%). *Chironomus* sp. had the highest index value (IRI = 60.80%) followed by *N. hibernica* (IRI = 17.40%). In April and May, the main diet of topmouth gudgeon was composed of zooplankton, Insecta and Malacostraca. Insecta was particularly consumed in relatively high numbers. Insecta was also the main prey item of topmouth gudgeon in June. The main diet of topmouth gudgeon consisted of insect together with zooplankton. However, in August, members of Insecta, Annelida, zooplankton and phytoplankton were the main prey items of topmouth gudgeon (**Figure 2**).

#### **3.3. Fullness, diversity and similarity indices**

Maximum fullness index was in April, whereas minimum fullness index was observed in July (**Figure 3**). According to Shannon-Weaver index (H′ ), the maximum values (H′ =1.80) were found in May and the minimum values (H′ =0.79) were determined in April. A Wilcoxon matchedpairs signed rank test was conducted to determine whether there was a spatial difference in the ranking of two stations. The results revealed significant effects of spatial variation on occurrence of *Mesocyclops leuckarti* and nauplii in stomach content (Z = 3.39, p < 0.001 and Z = 2.37, p < 0.05, respectively). A post-hoc test using Tukey-Kramer HSD tests showed the significant differences between Station 1 and 2 (p < 0.05). The results showed spatial changes of *M. leuckarti* and nauplii in the lake that they were only recorded in stomach content of fishes at Station 1.

A Kruskal-Wallis test was operated to determine whether there was a temporal difference in occurrence of taxa in stomach content. The results of analysis revealed significant differences in occurrence of *C. curvispinum*, *M. leuckarti* and *N. hibernica* (*x*<sup>2</sup> (4) = 18.54, p < 0.01; *x*<sup>2</sup> (4) = 15.78, p < 0.01 and *x*<sup>2</sup> (4) = 24.09, p < 0.001, respectively). A post hoc rank sums test indicated that there were significant differences between April and all other months for *N. hibernica* and *C. curvispinum*, whereas significant differences occurred between July and April, May, August for *M. leuckarti* (Tukey–Kramer HSD, p < 0.05). Indeed, the ratios of *N. hibernica* and *C. curvispinum* in stomach content were significantly higher in April, and *M. leuckarti* only occurred in July. This analysis showed that there was a clear temporal variation in occurrence of species. A Kruskal-Wallis test also showed the significant monthly differences for *Alona guttata*, *Chironomus* sp., *Chironomus* (pupa), *Chydorus sphaericus* and *Graptoleberis testudinaria* whose ratios in stomach content were significantly higher in May than the other months. However, a post-hoc test did not correct the significant differences (Tukey-Kramer HSD, p > 0.05). A Kruskal-Wallis test revealed that there were significant effects on occurrence of *N. hibernica* in stomach content due to both fish weight and length (*x*<sup>2</sup> (3) = 24.57, p < 0.001 and *x*<sup>2</sup> (5) = 26.88, p < 0.001, respectively). A post hoc rank sums test also corrected that there was a significant difference between the group ≤5 g and all other weight groups for *N. hibernica* (Tukey-Kramer HSD, p < 0.05). In addition, Tukey-Kramer HSD showed a significant difference between the length group of 6.0–6.9 cm and 7.0–7.9 cm together with 8.0–8.9 cm (p < 0.05). The longer groups (*P.parva*) in whose stomach contents *N. hibernica* was not recorded were not significantly differentiated than length group of 6.0–6.9 cm.

**3.2. The diet composition of topmouth gudgeon**

362 Selected Studies in Biodiversity

**3.3. Fullness, diversity and similarity indices**

in May and the minimum values (H′

p < 0.01 and *x*<sup>2</sup>

(**Figure 3**). According to Shannon-Weaver index (H′

in occurrence of *C. curvispinum*, *M. leuckarti* and *N. hibernica* (*x*<sup>2</sup>

stomach content due to both fish weight and length (*x*<sup>2</sup>

ton, Insecta, Malacostraca, Annelida and unidentified eggs (**Table 2**).

and phytoplankton were the main prey items of topmouth gudgeon (**Figure 2**).

The diet of topmouth gudgeon in the lake was found to consist of phytoplankton, zooplank-

Total weight of 1427 prey items was 8.49 g. Insects were the most frequently ingested prey with 66.52% by weight. *Chironomus* sp. (47.42%) was the dominant prey insects followed by *Chelicorophium curvispinum* (26.26%) and *Chironomus* pupa (11.80%) in terms of weight. Relative Importance Index (IRI) showed that prey Insecta (64.71%) had more importance than the zooplankton prey categories (20.03%) and *C. curvispinum* (14.78%). *Chironomus* sp. had the highest index value (IRI = 60.80%) followed by *N. hibernica* (IRI = 17.40%). In April and May, the main diet of topmouth gudgeon was composed of zooplankton, Insecta and Malacostraca. Insecta was particularly consumed in relatively high numbers. Insecta was also the main prey item of topmouth gudgeon in June. The main diet of topmouth gudgeon consisted of insect together with zooplankton. However, in August, members of Insecta, Annelida, zooplankton

Maximum fullness index was in April, whereas minimum fullness index was observed in July

pairs signed rank test was conducted to determine whether there was a spatial difference in the ranking of two stations. The results revealed significant effects of spatial variation on occurrence of *Mesocyclops leuckarti* and nauplii in stomach content (Z = 3.39, p < 0.001 and Z = 2.37, p < 0.05, respectively). A post-hoc test using Tukey-Kramer HSD tests showed the significant differences between Station 1 and 2 (p < 0.05). The results showed spatial changes of *M. leuckarti* and nauplii in the lake that they were only recorded in stomach content of fishes at Station 1. A Kruskal-Wallis test was operated to determine whether there was a temporal difference in occurrence of taxa in stomach content. The results of analysis revealed significant differences

there were significant differences between April and all other months for *N. hibernica* and *C. curvispinum*, whereas significant differences occurred between July and April, May, August for *M. leuckarti* (Tukey–Kramer HSD, p < 0.05). Indeed, the ratios of *N. hibernica* and *C. curvispinum* in stomach content were significantly higher in April, and *M. leuckarti* only occurred in July. This analysis showed that there was a clear temporal variation in occurrence of species. A Kruskal-Wallis test also showed the significant monthly differences for *Alona guttata*, *Chironomus* sp., *Chironomus* (pupa), *Chydorus sphaericus* and *Graptoleberis testudinaria* whose ratios in stomach content were significantly higher in May than the other months. However, a post-hoc test did not correct the significant differences (Tukey-Kramer HSD, p > 0.05). A Kruskal-Wallis test revealed that there were significant effects on occurrence of *N. hibernica* in

p < 0.001, respectively). A post hoc rank sums test also corrected that there was a significant difference between the group ≤5 g and all other weight groups for *N. hibernica* (Tukey-Kramer

(4) = 24.09, p < 0.001, respectively). A post hoc rank sums test indicated that

), the maximum values (H′

=0.79) were determined in April. A Wilcoxon matched-

(4) = 18.54, p < 0.01; *x*<sup>2</sup>

(3) = 24.57, p < 0.001 and *x*<sup>2</sup>

=1.80) were found

(4) = 15.78,

(5) = 26.88,


**Table 2.** Diet composition of topmouth gudgeon in Lake Eğirdir between 2010 and 2011.

**Figure 2.** Monthly diet variations of topmouth gudgeon in Lake Eğirdir between 2010 and 2011 (IRI: Relative importance index).

**Figure 3.** Variations in fullness index and empty stomach of topmouth gudgeon.

Although similar differences were determined for *N. hibernica* and *Chironomus* sp. with a Wilcoxon test, a post-hoc test did not correct the significant differences (Tukey-Kramer HSD, p > 0.05). Topmouth gudgeon was significantly different for months because of high Schoener Overlap Index (C < 0.80). Diet composition showed similarities between 7.0–7.9 cm and 10.0– 10.9 cm (C = 0.80) and 8.0–8.9 cm and 10.0–10.9 cm (C = 0.87) size classes of topmouth gudgeon.

**Figure 4.** Stomach contents in different size classes of topmouth gudgeon in Lake Eğirdir between 2010 and 2011. Zoo, zooplankton; Chr, *Chironomus* sp.; Chr. (pup), *Chironomus* (pupa); Cor, *C. curvispinum*; Tr, Trichoptera larvae; An,

Prey Selection of *Pseudorasbora parva* (Temminck and Schlegel, 1846) in a Freshwater Ecosystem (Lake Eğirdir/Turkey)

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365

Annelida; Ph, phytoplankton and Un.eg., unidentified egg.

**Figure 4.** Stomach contents in different size classes of topmouth gudgeon in Lake Eğirdir between 2010 and 2011. Zoo, zooplankton; Chr, *Chironomus* sp.; Chr. (pup), *Chironomus* (pupa); Cor, *C. curvispinum*; Tr, Trichoptera larvae; An, Annelida; Ph, phytoplankton and Un.eg., unidentified egg.

Although similar differences were determined for *N. hibernica* and *Chironomus* sp. with a Wilcoxon test, a post-hoc test did not correct the significant differences (Tukey-Kramer HSD, p > 0.05). Topmouth gudgeon was significantly different for months because of high Schoener Overlap Index (C < 0.80). Diet composition showed similarities between 7.0–7.9 cm and 10.0– 10.9 cm (C = 0.80) and 8.0–8.9 cm and 10.0–10.9 cm (C = 0.87) size classes of topmouth gudgeon.

**Figure 3.** Variations in fullness index and empty stomach of topmouth gudgeon.

**Figure 2.** Monthly diet variations of topmouth gudgeon in Lake Eğirdir between 2010 and 2011 (IRI: Relative importance

index).

364 Selected Studies in Biodiversity

**3.5. Prey selection**

shown in **Figure 6**.

**4. Discussions**

Feeding rates was compared in the diet and in the ecosystems in 2010. *Chironomus* sp. was the commonly abundant prey in the ecosystem; it was a positively selected food item and was not statistically significant. Also, *A. guttata* (V = 0.062, X2 = 0.781, p > 0.05), *A. quadrangularis* (V = −0.024, X2 = 0.123, p > 0.05), *C. curvispinum* (V = −0.037, X2 = 0.277, p > 0.05)*, C. rectangula* (V = 0.098, X2 = 1.931, p > 0.05), *G. testudinaria* (V = 0.055, X2 = 0.616, p > 0.05), *M. leuckarti* (V = 0.049, X2 = 0.499, p > 0.05) and nauplii (V = 0.015, X2 = 0.047, p > 0.05) were found in the ecosystems, but was not preferred by topmouth gudgeon. Similarly, *Pediastrum* sp. (V = −0.141, X2 = 4.016, p < 0.01) and *N. hibernica* (V = −0.221, X2 = 9.818, p < 0.01) were avoided by topmouth gudgeon despite their high abundance in the lake Eğirdir ecosystem (**Figure 5**). Some organisms in the diet of topmouth gudgeon are

Prey Selection of *Pseudorasbora parva* (Temminck and Schlegel, 1846) in a Freshwater Ecosystem (Lake Eğirdir/Turkey)

http://dx.doi.org/10.5772/intechopen.70471

367

The fish fauna of Lake Eğirdir was previously reported to consist of *Cyprinus carpio, Carassius gibelio, Tinca tinca, Vimba vimba, Capoeta pestai, Sander lucioperca, Alburnus chalcoides,* 

**Figure 6.** Some organisms in the diet of topmouth gudgeon (a) *G. testudinaria,* (b) *D. cucullata,* (c) *C. curvispinum,*

(d) *N. hibernica,* (e) *B. longirostris* and (f) *C. sphaericus* (scale: 100 micron).

**Figure 5.** Percentages of the lake ecosystems and diet of topmouth gudgeon in Lake Eğirdir in 2010 (May, June, July, August).

#### **3.4. Different size classes of diet composition**

Different size classes of topmouth gudgeon were characterized by different diet compositions (**Figure 4**). Prey zooplankton species was consumed by 58.90% of the 6.0- to 6.9-cm sized topmouth gudgeon, with a large weight (0.39%) percentage. However, it consumed in the 6.0–6.9 cm size class in the diet in terms of numbers (75.12%). In the stomachs of topmouth gudgeon of the 8.0–8.9 cm size class, only phytoplankton species was determined. In >10 cm sized topmouth gudgeon prey, Insecta species was identified (**Figure 4**).

Prey Selection of *Pseudorasbora parva* (Temminck and Schlegel, 1846) in a Freshwater Ecosystem (Lake Eğirdir/Turkey) http://dx.doi.org/10.5772/intechopen.70471 367

#### **3.5. Prey selection**

Feeding rates was compared in the diet and in the ecosystems in 2010. *Chironomus* sp. was the commonly abundant prey in the ecosystem; it was a positively selected food item and was not statistically significant. Also, *A. guttata* (V = 0.062, X2 = 0.781, p > 0.05), *A. quadrangularis* (V = −0.024, X2 = 0.123, p > 0.05), *C. curvispinum* (V = −0.037, X2 = 0.277, p > 0.05)*, C. rectangula* (V = 0.098, X2 = 1.931, p > 0.05), *G. testudinaria* (V = 0.055, X2 = 0.616, p > 0.05), *M. leuckarti* (V = 0.049, X2 = 0.499, p > 0.05) and nauplii (V = 0.015, X2 = 0.047, p > 0.05) were found in the ecosystems, but was not preferred by topmouth gudgeon. Similarly, *Pediastrum* sp. (V = −0.141, X2 = 4.016, p < 0.01) and *N. hibernica* (V = −0.221, X2 = 9.818, p < 0.01) were avoided by topmouth gudgeon despite their high abundance in the lake Eğirdir ecosystem (**Figure 5**). Some organisms in the diet of topmouth gudgeon are shown in **Figure 6**.

**Figure 6.** Some organisms in the diet of topmouth gudgeon (a) *G. testudinaria,* (b) *D. cucullata,* (c) *C. curvispinum,*

(d) *N. hibernica,* (e) *B. longirostris* and (f) *C. sphaericus* (scale: 100 micron).
