Kamaruddin, I.S. (2011). Diversity and feeding guilds of fish populations in Pengkalan Gawi - Pulau Dula section of Tasik Kenyir Terengganu, Malaysia. Master of science thesis. Universiti Putra Malaysia. 94p.
CHAPTER 4
RESULTS
4.1 Species Diversity of Fish
A total of 274 fish individual comprising 13 species from 5 families were collected from Pengkalan Gawi– Pulau Dula section of Tasik Kenyir, Terengganu during the sampling period from February 2008 to January 2009 (Table 4.1). Cyprinidae was the most dominant family with 8 species comprising 56.19% of the total fish caught. Family Notopteridae contributed 27.37% meanwhile families Bagridae, Nandidae and Ophicephalidae each comprised approximately about 8% or less of the total sample.
Overall, the fish species diversity mean value using the Shannon-Weaver index showed a value of 1.41±0.23. The species evenness mean value using Pielou Evenness index was at 0.81±0.13 and the species richness mean value using Margalef index was 3.53±0.62 (Table 4.2). In terms of fish individual, the most abundant species was Barbodes schwanenfeldii (Lampam Sungai) with 98 individual fish comprising 35.77% of the total fish caught. The mean standard length was 15.8±2.4 cm with mean weight of 111.8±52.0 g. This was then followed by Notopterus sp. (Belida) (27.37%), Hampala macrolepidota (Sebarau) (16.06%) and Hemibagrus nemurus (Baung) (8.03%). The rest of the species each comprised about 5% or less from the total fish captured (Table 4.1).
Table 4.1: List of the family, species, common name, number of individual, percentage composition (in parentheses), mean length and mean weight of fish population during the sampling period from February 2008 to January 2009 in Pengkalan Gawi – Pulau Dula section of Tasik Kenyir, Terengganu.
Family | Fish species | Common name | No. of individual | Mean length (cm±SD) | Mean weight (g±SD) |
Cyprinidae | Barbodes schwanenfeldii (Bleeker) | Lampam Sungai | 98 (35.77) | 15.8±2.4 | 111.8±52.0 |
Hampala macrolepidota (Van Hasselt) | Sebarau | 44 (16.06) | 21.6±2.7 | 240.7±88.8 | |
Cyclocheilichthys apogon (C&V) | Temperas | 4 (1.46) | 14.2±0.7 | 79.1±13.4 | |
Osteochilus hasselti (C&V) | Terbol | 3 (1.09) | 15.3±0.4 | 121.5±6.3 | |
Osteochilus vittatus (C&V) | Rong | 2 (0.73) | 15.6±0.1 | 82.4±14.8 | |
Chela anomalura (Van Hasselt) | Lalang | 1 (0.36) | 13.8±0.0 | 23.2±0.0 | |
Labiobarbus lineatus (Sauvage) | Kawan | 1 (0.36) | 17.1±0.0 | 80.4±0.0 | |
Probarbus jullieni (Sauvage) | Temoleh | 1 (0.36) | 40.6±0.0 | 220.0±0.0 | |
Notopteridae | Notopterus sp. (Lacepede) | Belida | 75 (27.37) | 21.2±2.0 | 94.1±22.6 |
Bagridae | Hemibagrus nemurus (Valenciennes) | Baung | 22 (8.03) | 22.8±3.0 | 183.3±55.8 |
Nandidae | Pristolepis fasciatus (Bleeker) | Patong | 10 (3.65) | 11.9±0.7 | 80.9±11.4 |
Ophicephalidae | Channa micropeltes (C&V) | Toman | 12 (4.38) | 31.9±6.2 | 554.8±405.6 |
Channa striatus (Bloch) | Haruan | 1 (0.36) | 25.4±0.0 | 350.0±0.0 | |
Total | 274 |
Table 4.2: Three species diversity index at each month and station in Pengkalan Gawi – Pulau Dula section of Tasik Kenyir from February 2008 to January 2009.
Station and month | No. of species | No. of individual | Shannon-Weaver index | Pielou Evenness index | Margalef Richness index |
Mean values (mean±SD) Stations Pulau Dula (A) Sungai Ikan (B) Pulau Pupi (C) | - 9 11 7 | - 72 128 74 | 1.41±0.23 0.97 1.66 1.67 | 0.81±0.13 0.44 0.69 0.86 | 3.53±0.62 4.31 4.75 3.21 |
Months February 2008 March April May June July August September October November December January 2009 | 6 6 5 6 7 5 5 4 3 6 6 6 | 51 28 14 35 28 14 17 7 9 26 17 28 | 1.18 1.65 1.39 1.55 1.64 1.40 1.23 1.28 1.06 1.51 1.40 1.66 | 0.66 0.92 0.86 0.87 0.84 0.87 0.76 0.92 0.96 0.84 0.78 0.93 | 2.93 3.46 3.49 3.24 4.15 3.49 3.25 3.55 2.10 3.53 4.06 3.46 |
4.1.1 Spatial Species Diversity
In terms of number of fish species caught (S) at the study stations, there were 11 species of fish found in Sungai Ikan compared to only 9 species in Pulau Dula and 7 species found in Pulau Pupi (Table 4.3). The Shannon-Weaver diversity index showed very little difference between Pulau Pupi and Sungai Ikan (Table 4.2). The diversity index for Pulau Pupi was 1.67 whereas for Sungai Ikan it was 1.66. Meanwhile, Pulau Dula recorded with the least value at 0.97.
The Pielou evenness index was recorded the highest in Pulau Pupi at 0.86. This indicated that the number of individual fish for each species were more even in Pulau Pupi when compared to the other stations. Meanwhile, results for the Margalef index showed the highest in Sungai Ikan at 4.75 and the lowest was recorded in Pulau Pupi at 3.21.
In terms of number of individual fish (n), Sungai Ikan had the highest with 128 individual fish. This station was dominated by Notopterus sp. comprising 43.75% from the total fish caught at the station. In Pulau Dula, the total number of individual fish was 72 and B. schwanenfeldii (77.78%) was the most abundant species. Meanwhile Pulau Pupi was dominated by H. macrolepidota comprising 32.43% from the total of 74 individual fish (Table 4.3).
Table 4.3: Number of individual and mean standard length (cm±SD) (in parentheses) of different fish species at each station in Pengkalan Gawi – Pulau Dula section of Tasik Kenyir, Terengganu from February 2008 to January 2009.
Species | Pulau Dula (A) | Sungai Ikan (B) | Pulau Pupi (C) |
B. schwanenfeldii | 56 (15.1±2.5) | 28 (16.7±1.9) | 14 (17.2±1.9) |
Notopterus sp. | 4 (20.3±2.1) | 56 (21.5±2.1) | 15 (20.1±1.1) |
H. macrolepidota | 2 (21.4±2.6) | 18 (21.6±1.5) | 24 (21.7±3.4) |
H. nemurus | 2 (18.1±0.9) | 8 (23.7±3.4) | 12 (23.0±2.2) |
P. fasciatus | 3 (12.4±0.1) | 3 (11.8±1.1) | 4 (11.7±0.4) |
C. micropeltes | 1 (44.8±0.0) | 7 (28.2±2.2) | 4 (35.0±5.6) |
C. apogon | 1 (13.8±0.0) | 2 (14.8±0.2) | 1 (13.4±0.0) |
O. hasselti | - | 3 (15.3±0.4) | - |
O. vittatus | 2 (15.6±0.1) | - | - |
C. anomalura | - | 1 (13.8±0.0) | - |
L. lineatus | 1 (17.0±0.0) | - | - |
C. striatus | - | 1 (25.4±0.0) | - |
P. jullieni | - | 1 (40.6±0.0) | - |
Total | 72 | 128 | 74 |
4.1.2 Temporal Species Diversity
For monthly variations, the highest number of species caught (S) was recorded in the month of June with 7 species and the lowest was recorded in the month of October with only 3 species (Table 4.4). Six species of fish were caught in the months of February, March, May, November, December 2008 and January 2009 meanwhile 5 species of fish were caught during sampling in months of April, July and August 2008.
The Shannon-Weaver index was highest in the months of January 2009 at 1.66 and the lowest was recorded in October 2008 at 1.06 (Table 4.2). The month of October also showed that it was the highest in terms of Pielou evenness index at 0.92 but it was the lowest in terms of Margalef index at 2.10. In contrast to that, the lowest Pielou index was recorded in February (0.66) while the highest Margalef index was recorded in June (4.15).
In this study, the highest number of individual fish captured (n) was recorded in the month of February with 51 individuals. This month was dominated by B. schwanenfeldii with 47.36% from the total fish caught in the month. B. schwanenfeldii was also dominant in July, August, October, November 2008 and January 2009, and it presents every months except in September (Table 4.4). Besides this species, Notopterus sp. and H. macrolepidota were also present in the monthly samples. This clearly shows that this study area was dominated by these 3 species while the other species showed variation in their composition every month.
Table 4.4: Number of individual and mean standard length (cm±SD) (in parentheses) of different fish species each month in Pengkalan Gawi – Pulau Dula section of Tasik Kenyir, Terengganu from February 2008 to January 2009.
Species | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Jan | |
B. schwanenfeldii | 27 (15.8±2.6) | 5 (15.1±1.3) | 5 (15.1±0.9) | 9 (13.9±2.5) | 8 (14.9±1.9) | 6 (15.4±1.5) | 10 (14.2±1.7) | - | 4 (17.5±2.9) | 9 (18.1±1.0) | 6 (16.2±1.3) | 9 (18.1±2.2) | |
Notopterus sp. | 16 (21.4±1.8) | 7 (21.4±1.2) | 1 (18.2±0.0) | 14 (20.0±0.8) | 6 (21.8±3.4) | 3 (19.0±0.2) | 2 (19.5±0.7) | 2 (19.6±1.0) | 3 (23.0±3.9) | 7 (22.1±2.0) | 7 (21.6±1.5) | 7 (22.5±2.3) | |
H. macrolepidota | 4 (20.4±1.2) | 8 (23.4±2.7) | 2 (18.3±2.2) | 3 (20.1±1.7) | 8 (22.0±2.7) | 3 (21.3±2.6) | 2 (20.4±3.3) | 3 (21.4±0.6) | 2 (17.9±7.6) | 6 (22.7±1.6) | 1 (22.0±0.0) | 2 (23.9±1.1) | |
H. nemurus | 2 (26.6±5.7) | 4 (22.1±2.5) | 5 (21.9±2.2) | 4 (21.7±3.7) | 3 (24.0±1.6) | - | - | - | - | - | 1 (26.7±0.0) | 3 (21.8±2.0) | |
P. fasciatus | 1 (13.2±0.0) | - | 1 (11.6±0.0) | 2 (11.9±0.6) | 1 (11.0±0.0) | 1 (11.3±0.0) | - | - | - | - | 1 (11.4±0.0) | 3 (12.4±0.1) | |
C. micropeltes | - | 3 (40.4±6.4) | - | 3 (31.5±1.1) | 1 (31.7±0.0) | - | - | 1 (27.0±0.0) | - | - | - | 4 (26.9±1.2) | |
C. apogon | - | - | - | - | - | - | 1 (13.8±0.0) | 1 (13.4±0.0) | - | 2 (14.8±0.2) | - | - | |
O. hasselti | - | - | - | - | - | - | 2 (15.2±0.6) | - | - | - | 1 (15.4±0.0) | - | |
O. vittatus | - | - | - | - | 1 (15.7±0.0) | 1 (15.5±0.0) | - | - | - | - | - | - | |
C. anomalura | - | - | - | - | - | - | - | - | - | 1 (13.8±0.0) | - | - | |
L. lineatus | - | 1 (17.1±0.0) | - | - | - | - | - | - | - | - | - | - | |
C. striatus | 1 (25.4±0.0) | - | - | - | - | - | - | - | - | - | - | - | |
P. jullieni | - | - | - | - | - | - | - | - | - | 1 (40.6±0.0) | - | - | |
Total | 51 | 28 | 14 | 35 | 28 | 14 | 17 | 7 | 9 | 26 | 17 | 28 |
4.2 Feeding Habits of Fish
A total of 261 individuals fish belonging to 6 most dominant species were analyzed for feeding data in this study. The number of individual fish ranged from 10 individuals for P. fasciatus to 98 individuals for B. schwanenfeldii. Altogether, 4 species of fish namely B. schwanenfeldii, Notopterus sp., H. nemurus and P. fasciatus consumed Aquatic insect as the main food item. Meanwhile, Fish food item dominated the diets of H. macrolepidota and C. micropeltes. Plant materials although not the most abundant food item found in the stomach of any species, it was present in the stomach of all 6 species (Table 4.5).
In terms of the Trophic Level (Troph), the values for all species ranged from 2.74±0.36 for P. fasciatus to 3.56±0.63 for C. micropeltes (Table 4.5). Four species were categorized as omnivore species due to values less than 3 which were B. schwanenfeldii, Notopterus sp., H. macrolepidota and P. fasciatus, while H. nemurus and C. micropeltes were predators.
For B. schwanenfeldii, although the percentage composition of Aquatic insect in the stomach was high (62.7%), the occourrence of this food item was relatively low (22.5%). The other food item that was abundant in the diet of B. schwanenfeldii was Plant materials with 16.9% of the total food item consumed and it occurred about 22.1% from the total gut examined. This species was classified as omnivorous where both animal and plant origins of food items were equally consumed. Crustaceans (shrimp) food item was not found in the stomach of B. schwanenfeldii in this study.
The percentage composition of Aquatic insect for Notopterus sp. was 64.6% and it occurred about 21.6% from the total gut examined. Subsequently, about 14.8% of stomach occurred with Plant materials and 14.5% of stomach occurred with Detritus as the other type of diets of this species. Besides that, Notopterus sp. was the only species in this study which consumed all of the food items classified. Overall, this species was classified as omnivore species with Troph of 2.86±0.34.
P. fasciatus was also classified as omnivore species that contained mostly on Aquatic insect (37.9%) and Phytoplankton (40.5%) in the diets. It occurred in 22.6% and 45.2% of total stomach of this species respectively, and it was the only species that fed in high volume of Mollusks (snail) at 9.5%. On the other hand, although H. macrolepidota was ingested frequently on Fish food item, it was classified as omnivore species. This is due to the equal proportion of animal and plant origin of food item consumed by this species in total of 51.5% and 49.5% respectively.
The Troph value for H. nemurus was 3.11±0.41, thus it was categorized as insect feeder which contained 77.0% of Aquatic insect in the stomach. This species was also known as insectivore species. Other food items in H. nemurus were also abundant such as Crustaceans, Detritus and Fish food items.
C. micropeltes was numerically the most representative with Fish food item at 62.5% and it occurred from 71.4% of the stomach of this species. Therefore, these species was grouped under fish predator or piscivore species. The other food item consumed by C. micropeltes was Plant materials representing about 37.5% from the total of food item.
Meanwhile, mean Stomach Fullness (SF) for different fish species in this study ranged from 1.5±1.7 for C. micropeltes, to 3.4±0.7 for P. fasciatus, where most of the mean values were less than 2. One species, P. fasciatus showed that none of the stomach of this species was empty. Species like B. schwanenfeldii and Notopterus sp. were found with 14% and 1.3% of empty stomach respectively. Fullness degrees of these species are shown in Table 4.5.
Table 4.5: Percentage Composition of Food Item (%CFI), Frequency of Occurrence of Food Item (%FOFI), Stomach Fullness (SF) and the Trophic Level (Troph) for six most dominant species in Pengkalan Gawi – Pulau Dula Section of Tasik Kenyir from February 2008 to January 2009.
Species | Food item | %CFI | %FOFI | ||
B. schwanenfeldii | Fish | 0.1 | 0.7 | ||
(Troph= 2.85±0.33) | Aquatic insect | 62.8 | 22.5 | ||
(SF= 1.7±1.2) | Mollusks | 3.0 | 3.6 | ||
Crustaceans | - | - | |||
Plant Materials | 16.9 | 22.1 | |||
Detritus | 2.1 | 6.1 | |||
Copepods | 2.2 | 6.4 | |||
Cladocerans | 1.3 | 5.0 | |||
Rotifer | 1.5 | 5.0 | |||
Bacillariophyta | 3.2 | 8.2 | |||
Chlorophyta | 3.2 | 9.3 | |||
Euglenophyta | 0.8 | 3.6 | |||
Cyanophyta | 2.3 | 5.7 | |||
Unidentified | 0.6 | 1.8 | |||
Notopterus sp. | Fish | 0.9 | 2.2 | ||
(Troph= 2.86±0.34) | Aquatic insect | 64.6 | 21.6 | ||
(SF= 3.0±1.1) | Mollusks | 0.1 | 0.9 | ||
Crustaceans | 2.3 | 7.7 | |||
Plant Materials | 13.3 | 14.8 | |||
Detritus | 7.2 | 14.5 | |||
Copepods | 0.7 | 3.4 | |||
Cladocerans | 1.6 | 3.4 | |||
Rotifer | 1.1 | 3.7 | |||
Bacillariophyta | 1.9 | 4.9 | |||
Chlorophyta | 1.5 | 5.2 | |||
Euglenophyta | 0.5 | 3.1 | |||
Cyanophyta | 1.5 | 4.0 | |||
Unidentified | 2.8 | 10.5 | |||
H. macrolepidota | Fish | 24.3 | 31.3 | ||
(Troph= 2.96±0.47) | Aquatic insect | 13.5 | 14.1 | ||
(SF= 1.8±1.7) | Mollusks | 1.0 | 1.6 | ||
Crustaceans | 7.8 | 7.8 | |||
Plant Materials | 7.8 | 9.4 | |||
Detritus | 8.7 | 14.1 | |||
Copepods | 4.9 | 6.3 | |||
Cladocerans | - | - | |||
Rotifer | - | - | |||
Bacillariophyta | 8.7 | 4.7 | |||
Chlorophyta | 14.6 | 4.7 | |||
Euglenophyta | 1.0 | 1.6 | |||
Cyanophyta | 5.8 | 1.6 | |||
Unidentified | 1.9 | 3.1 | |||
H. nemurus | Fish | 3.4 | 11.4 | ||
(Troph= 3.11±0.41) | Aquatic insect | 77.0 | 38.6 | ||
(SF= 1.9±1.7) | Mollusks | - | - | ||
Crustaceans | 7.5 | 20.5 | |||
Plant Materials | 2.9 | 11.4 | |||
Detritus | 7.5 | 13.6 | |||
Copepods | - | - | |||
Cladocerans | - | - | |||
Rotifer | - | - | |||
Bacillariophyta | - | - | |||
Chlorophyta | - | - | |||
Euglenophyta | - | - | |||
Cyanophyta | - | - | |||
Unidentified | 1.7 | 4.5 | |||
C. micropeltes | Fish | 62.5 | 71.4 | ||
(Troph= 3.56±0.63) | Aquatic insect | - | - | ||
(SF= 1.5±1.7) | Mollusks | - | - | ||
Crustaceans | - | - | |||
Plant Materials | 37.5 | 28.6 | |||
Detritus | - | - | |||
Copepods | - | - | |||
Cladocerans | - | - | |||
Rotifer | - | - | |||
Bacillariophyta | - | - | |||
Chlorophyta | - | - | |||
Euglenophyta | - | - | |||
Cyanophyta | - | - | |||
Unidentified | - | - | |||
P. fasciatus | Fish | 0.9 | 3.2 | ||
(Troph= 2.74±0.36) | Aquatic insect | 37.9 | 22.6 | ||
(SF= 3.4±0.7) | Mollusks | 9.5 | 6.5 | ||
Crustaceans | - | - | |||
Plant Materials | 0.9 | 3.2 | |||
Detritus | 0.9 | 3.2 | |||
Copepods | 6.0 | 6.5 | |||
Cladocerans | 1.7 | 3.2 | |||
Rotifer | 1.7 | 6.5 | |||
Bacillariophyta | 15.5 | 16.1 | |||
Chlorophyta | 12.1 | 12.9 | |||
Euglenophyta | 2.6 | 6.5 | |||
Cyanophyta | 10.3 | 9.7 | |||
Unidentified | - | - |
4.2.1 Spatial Feeding Habits of Fish
Three species of fish namely B. schwanenfeldii, Notopterus sp. and H. macrolepidota were determined their feeding habits according to spatial data. These species present in abundance at each station throughout the sampling period from February 2008 to January 2009.
The Troph value for Notopterus sp. showed that it was omnivorous at all stations. Meanwhile B. schwanenfeldii was omnivorous in Pulau Dula and Sungai Ikan but it was herbivorous in Pulau Pupi. The highest value was recorded in Sungai Ikan for B. schwanenfeldii (2.91±0.35) and in Pulau Pupi for Notopterus sp. (2.88±0.36). This was different with H. macrolepidota where it was omnivorous in Sungai Ikan but it found to be carnivorous in Pulau Dula and Pulau Pupi (Table 4.6).
Different kind of feeding habits from different stations were observed. The feeding habits in Pulau Dula were categorized into 2 groups which were omnivorous and carnivorous groups. B. schwanenfeldii and Notopterus sp. were classified as omnivorous due to the Troph was at 2.91±0.37 and 2.78±0.32 although both fish fed primarily on Aquatic insect comprised of 62.6% and 57.1% respectively. H. macrolepidota at this station fed only on crustaceans (shrimp) thus it was categorized as shrimp predator species.
There was only one feeding type identified in Sungai Ikan which was omnivorous. Results for feeding habits of B. schwanenfeldii indicated that Plant materials occurred in fish stomach was higher (23.4%) than Aquatic insect (19.2%), but the composition of Plant materials consumed was lower (13.5%) when compared to Aquatic insect (71.7%). As such, B. schwanenfeldii was categorized as omnivorous in this station with Troph of 2.91±0.35. Notopterus sp. in this station was also omnivorous with Troph of 2.87±0.35. The highest proportion of food item was Aquatic insect and Plant Materials comprised about 64.8% and 15.7% from it diets respectively. Meanwhile, H. macrolepidota which fed mainly on Fish food item (23.5%) and Phytoplankton (56.9%) was recorded with Troph of 2.68±0.40.
Three feeding types were observed in Pulau Pupi including omnivorous, herbivorous and carnivorous. The feeding habits of Notopterus sp. was similar to the other stations (omnivore) although Aquatic insect was the main food item consumed (65.1%). B. schwanenfeldii at this station was different when compared to Pulau Dula and Sungai Ikan because it fed mainly on Plant Materials which composed about 64.8% of its diets and were categorized as herbivore species due to the low Troph value of 2.31±0.25. The only species categorized as carnivorous (Troph of 3.21±0.52) at this station was H. macrolepidota because it had highest composition of Aquatic insect and Fish food items (25.5% each) in the diets (Table 4.6).
Table 4.6: The Percentage Composition of Food Item (%CFI) and Frequency of Occurrence of Food Item (%FOFI) of three most dominant species at each station during the study period.
Station | Food item | B.schwanenfeldii | Notopterus sp. | H. macrolepidota | |||
%CFI | %FOFI | %CFI | %FOFI | %CFI | %FOFI | ||
Pulau | Fish | 0.1 | 0.7 | - | - | - | - |
Dula | Aquatic insect | 62.6 | 24.8 | 57.1 | 20.0 | - | - |
(A) | Mollusks | 5.7 | 3.3 | 1.3 | 6.7 | - | - |
Crustaceans | - | - | - | - | 100.0 | 100.0 | |
Plant Materials | 11.9 | 19.3 | 11.7 | 19.9 | - | - | |
Detritus | 1.0 | 3.3 | 16.9 | 20.0 | - | - | |
Copepods | 2.2 | 6.7 | - | - | - | - | |
Cladocerans | 1.0 | 3.3 | - | - | - | - | |
Rotifer | 2.5 | 7.3 | 1.3 | 6.7 | - | - | |
Bacillariophyta | 4.5 | 9.3 | - | - | - | - | |
Chlorophyta | 3.8 | 11.3 | 1.3 | 6.7 | - | - | |
Euglenophyta | 0.8 | 3.3 | - | - | - | - | |
Cyanophyta | 3.8 | 6.7 | 3.9 | 6.7 | - | - | |
Unidentified | 0.1 | 0.7 | 6.5 | 13.3 | - | - | |
Trophic Level | 2.91±0.37 | 2.78±0.32 | 3.37±0.58 | ||||
Sungai | Fish | 0.1 | 1.1 | 1.1 | 2.5 | 23.5 | 40.0 |
Ikan | Aquatic insect | 71.7 | 19.2 | 64.8 | 21.7 | 2.0 | 4.0 |
(B) | Mollusks | 0.3 | 2.1 | 0.1 | 0.8 | - | - |
Crustaceans | - | - | 2.7 | 9.4 | 5.9 | 8.0 | |
Plant Materials | 13.5 | 23.4 | 15.7 | 16.0 | 3.9 | 8.0 | |
Detritus | 2.3 | 6.4 | 6.2 | 13.9 | 7.8 | 16.0 | |
Copepods | 1.4 | 5.3 | 0.6 | 2.5 | - | - | |
Cladocerans | 1.5 | 7.4 | 1.5 | 3.3 | - | - | |
Rotifer | 0.8 | 3.2 | 0.8 | 3.7 | - | - | |
Bacillariophyta | 2.6 | 9.6 | 1.5 | 4.9 | 17.6 | 12.0 | |
Chlorophyta | 2.7 | 8.5 | 1.3 | 4.5 | 25.5 | 4.0 | |
Euglenophyta | 1.0 | 5.3 | 0.6 | 3.3 | 2.0 | 4.0 | |
Cyanophyta | 1.4 | 6.4 | 0.9 | 3.3 | 11.8 | 4.0 | |
Unidentified | 0.8 | 2.1 | 2.2 | 10.2 | - | - | |
Trophic Level | 2.91±0.35 | 2.87±0.35 | 2.68±0.40 | ||||
Pulau | Fish | - | - | 0.2 | 1.6 | 25.5 | 26.3 |
Pupi | Aquatic insect | 11.9 | 22.1 | 65.0 | 20.3 | 25.5 | 21.0 |
(C) | Mollusks | 3.1 | 8.3 | - | - | 2.0 | 2.6 |
Crustaceans | - | - | 1.0 | 3.1 | 7.8 | 5.3 | |
Plant Materials | 64.8 | 30.6 | 4.5 | 9.4 | 11.8 | 10.5 | |
Detritus | 7.0 | 16.7 | 9.2 | 15.6 | 9.8 | 13.2 | |
Copepods | 7.0 | 8.3 | 1.5 | 7.8 | 9.8 | 10.5 | |
Cladocerans | 2.3 | 5.6 | 2.5 | 4.7 | - | - | |
Rotifer | - | - | 2.2 | 3.1 | - | - | |
Bacillariophyta | - | - | 3.7 | 6.3 | - | - | |
Chlorophyta | 2.3 | 2.8 | 2.0 | 7.8 | 3.9 | 5.3 | |
Euglenophyta | - | - | 0.5 | 3.1 | - | - | |
Cyanophyta | - | - | 3.2 | 6.3 | - | - | |
Unidentified | 1.6 | 5.6 | 4.5 | 10.9 | 3.9 | 5.3 | |
Trophic Level | 2.31±0.25 | 2.88±0.36 | 3.21±0.52 | ||||
4.2.2 Temporal Feeding Habits of Fish
Variations on feeding habits between seasons were also observed in this study. Three most dominant species were determined their feeding habits according to temporal variations. These species were B. schwanenfeldii, Notopterus sp. and H. macrolepidota and they were present in the monthly samples throughout the study period from February 2008 to January 2009. Feeding habits of these species were computed quarterly and were grouped into February/April; May/July; August/October; and September/January.
Fish captured during February/April, May/July and August/October had Aquatic insect as the most dominant item, while those captured during September/January had Plant materials (Table 4.7). During February to April three groups of feeding habits were identified. These included insect feeder, omnivorous and fish predator. B. schwanenfeldii was an insect feeder with Troph value of 3.01±0.37. Aquatic insect was the highest food item consumed with 80.1% and it occurred in 31.3% of the stomach. Meanwhile, Notopterus sp. was categorized as omnivorous by having both Aquatic insect and Plant materials as the main contributor. The only fish predator during this season was H. macrolepidota with high Troph value of 3.73±0.65.
During May to July, three feeding habits were also observed. These included insect feeder, omnivorous and carnivorous. B. schwanenfeldii which fed in high proportion of Aquatic insect (80.5%) was classified as insect feeder (Troph value of 3.02±0.38). Notopterus sp. was categorized as omnivore species with Troph value of 2.96±0.38, while H. macrolepidota during this season consumed the most on Aquatic insect (41.6%) and Fish food item (33.3%) and was categorized as a carnivore fish species (Troph value of 3.48±0.55).
During August to October all of the species were categorized as omnivore species, feeding primarily on both Aquatic insect and Plant materials. B. schwanenfeldii during this season changed it feeding habits from insect feeder to omnivore species and the Troph value decreased to 2.53±0.23. Aquatic insect and Plant materials consumed by this species was at 28.7% and 18.7% respectively. Notopterus sp. during this season besides consumed on Aquatic insect (51.8%) was also consumed in high proportion of Detritus (15.0%). Meanwhile, H. macrolepidota changed it feeding strategy to omnivorous with Troph value of 2.42±0.28, fed mainly on Fish, Crustaceans (shrimp) and Phytoplankton.
Two types of feeding habits were categorized during September to January. These included herbivore and omnivore species. This season, B. schwanenfeldii changed their feeding strategy to herbivore species with Troph value of 2.39±0.21 which consumed largely on Plant Materials (53.9%). H. macrolepidota was also changed their diets fed primarily on Detritus (46.2%) and were classified as detritivore species. Meanwhile, Notopterus sp. remains as omnivorous with Troph of 2.90±0.35 (Table 4.7).
Table 4.7: Temporal data (quarterly) for the Percentage Composition of Food Item (%CFI), and Frequency of Occurrence of Food Item (%FOFI) of three most dominant species.
Station | Food item | B.schwanenfeldii | Notopterus sp. | H. macrolepidota | |||||||||||
%CFI | %FOFI | %CFI | %FOFI | %CFI | %FOFI | ||||||||||
February | Fish | 0.1 | 1.0 | 0.6 | 2.5 | 58.3 | 33.3 | ||||||||
to | Aquatic insect | 80.1 | 31.3 | 60.4 | 17.5 | 8.3 | 13.3 | ||||||||
April | Mollusks | 0.1 | 1.0 | 0.3 | 1.7 | - | - | ||||||||
Crustaceans | - | - | 1.8 | 7.5 | 8.3 | 13.3 | |||||||||
Plant Materials | 7.0 | 15.5 | 20.1 | 17.5 | 4.2 | 6.7 | |||||||||
Detritus | 1.5 | 1.9 | 7.1 | 15.0 | 4.2 | 6.7 | |||||||||
Copepods | 1.2 | 5.8 | 0.1 | 0.8 | 4.2 | 6.7 | |||||||||
Cladocerans | 1.2 | 5.8 | 1.5 | 5.0 | - | - | |||||||||
Rotifer | 1.2 | 5.8 | 1.0 | 5.0 | - | - | |||||||||
Bacillariophyta | 2.4 | 8.7 | 1.1 | 3.3 | 8.3 | 13.3 | |||||||||
Chlorophyta | 2.0 | 8.7 | 0.4 | 2.5 | - | -- | |||||||||
Euglenophyta | 1.1 | 5.8 | 0.6 | 4.2 | - | - | |||||||||
Cyanophyta | 1.4 | 6.8 | 1.8 | 5.8 | - | - | |||||||||
Unidentified | 0.7 | 1.9 | 3.2 | 11.7 | 4.2 | 6.7 | |||||||||
Trophic Level | 3.01±0.37 | 2.80±0.34 | 3.73±0.65 | ||||||||||||
May | Fish | - | - | - | - | 33.3 | 42.1 | ||||||||
to | Aquatic insect | 80.5 | 27.0 | 69.8 | 22.0 | 41.6 | 26.2 | ||||||||
July | Mollusks | 0.7 | 4.2 | - | - | 4.2 | 5.3 | ||||||||
Crustaceans | - | - | 4.9 | 14.3 | 4.2 | 5.3 | |||||||||
Plant Materials | 8.4 | 24.9 | 7.4 | 12.0 | - | - | |||||||||
Detritus | 0.4 | 2.1 | 3.4 | 11.0 | 8.3 | 10.5 | |||||||||
Copepods | 0.4 | 2.1 | 1.1 | 5.5 | 4.2 | 5.3 | |||||||||
Cladocerans | 1.8 | 6.3 | 1.8 | 3.3 | - | - | |||||||||
Rotifer | 1.4 | 6.3 | 1.4 | 3.3 | - | - | |||||||||
Bacillariophyta | 3.2 | 10.4 | 4.2 | 7.7 | - | - | |||||||||
Chlorophyta | 1.4 | 8.3 | 1.8 | 6.6 | - | - | |||||||||
Euglenophyta | 0.4 | 2.1 | 0.2 | 1.1 | - | - | |||||||||
Cyanophyta | 1.4 | 6.3 | 2.4 | 4.4 | - | - | |||||||||
Unidentified | - | - | 1.6 | 8.8 | 4.2 | 5.3 | |||||||||
Trophic Level | 3.02±0.38 | 2.96±0.38 | 3.48±0.55 | ||||||||||||
August | Fish | 0.6 | 1.8 | 5.0 | 7.7 | 4.9 | 15.4 | ||||||||
to | Aquatic insect | 28.7 | 9.1 | 51.8 | 11.9 | 2.5 | 7.6 | ||||||||
October | Mollusks | 2.9 | 5.5 | 0.6 | 3.8 | - | - | ||||||||
Crustaceans | - | - | 1.3 | 3.8 | 12.2 | 15.4 | |||||||||
Plant Materials | 18.7 | 18.2 | 6.9 | 7.7 | 4.9 | 7.7 | |||||||||
Detritus | 0.6 | 1.8 | 15.0 | 15.4 | - | - | |||||||||
Copepods | 5.8 | 9.1 | 1.9 | 7.7 | 7.3 | 15.4 | |||||||||
Cladocerans | 2.9 | 7.3 | 0.6 | 3.8 | - | - | |||||||||
Rotifer | 4.7 | 7.3 | 2.5 | 3.8 | - | - | |||||||||
Bacillariophyta | 11.7 | 12.7 | 1.9 | 3.8 | 17.1 | 7.7 | |||||||||
Chlorophyta | 10.5 | 14.5 | 5.0 | 11.5 | 34.1 | 15.4 | |||||||||
Euglenophyta | 1.2 | 3.6 | 0.6 | 3.8 | 2.4 | 7.7 | |||||||||
Cyanophyta | 11.7 | 9.1 | 0.6 | 3.8 | 14.6 | 7.7 | |||||||||
Unidentified | - | - | 6.3 | 11.5 | - | - | |||||||||
Trophic Level | 2.53±0.23 | 2.83±0.35 | 2.42±0.28 | ||||||||||||
November | Fish | - | - | 0.9 | 2.8 | 7.1 | 7.7 | ||||||||
to | Aquatic insect | 13.3 | 15.2 | 69.3 | 24.7 | 7.2 | 7.6 | ||||||||
January | Mollusks | 13.8 | 6.1 | - | - | - | - | ||||||||
Crustaceans | - | - | 0.6 | 2.8 | - | - | |||||||||
Plant Materials | 53.9 | 28.8 | 11.2 | 18.1 | 35.7 | 30.8 | |||||||||
Detritus | 6.4 | 19.7 | 8.8 | 16.7 | 42.9 | 46.2 | |||||||||
Copepods | 5.0 | 9.1 | 0.9 | 4.2 | - | - | |||||||||
Cladocerans | 0.4 | 1.5 | 1.9 | 1.4 | - | - | |||||||||
Rotifer | 0.7 | 1.5 | 0.4 | 2.8 | - | - | |||||||||
Bacillariophyta | 0.7 | 3.0 | 0.6 | 2.8 | - | - | |||||||||
Chlorophyta | 3.9 | 7.6 | 1.7 | 5.6 | 7.1 | 7.7 | |||||||||
Euglenophyta | 0.4 | 1.5 | 0.7 | 4.2 | - | - | |||||||||
Cyanophyta | 0.4 | 1.5 | 0.4 | 1.4 | - | - | |||||||||
Unidentified | 1.1 | 4.5 | 2.6 | 12.5 | - | - | |||||||||
Trophic Level | 2.39±0.21 | 2.90±0.35 | 2.26±0.24 | ||||||||||||
4.3 Length-Weight Relationship and Condition Factor of Fish
Results for the length-weight relationship of three most dominant species were computed using regression analysis. The length-weight equations were calculated as for B. schwanenfeldii, Log10W = Log10−1.322 + 2.784 Log10L (r2=0.879); Notopterus sp., Log10W = Log10−0.562 + 1.905 Log10L (r2=0.592); and H. macrolepidota, Log10W = Log10−1.704 + 3.043 Log10L (r2=0.936). The r2 values for all speices were greter than 0.5, while the b values (slopes) ranged from 1.905 for Notopterus sp. to 3.043 for H. macrolepidota. Table 4.8 showed the length-weight relationship parameters (a, b and r2) for three species during the study period.
Table 4.8: Length range and the length-weight relationship parameters (a, b and r2) of three most dominant species in the Pengkalan Gawi– Pulau Dula section of Tasik Kenyir, Terengganu from February 2008 to January 2009.
Species of fish | Length range (cm) | a | b | r2 |
B. schwanenfeldii | 10.5 - 22.9 | -1.322 | 2.784 | 0.879 |
Notopterus sp. | 18.0 - 28.5 | -0.562 | 1.905 | 0.592 |
H. macrolepidota | 12.5 - 29.0 | -1.704 | 3.043 | 0.936 |
Overall, data for the Condition Factor (K) were calculated for B. schwanenfeldii varied from 1.58 to 4.25, for Notopterus sp. the K varied from 0.31 to 1.89, while it was ranged from 1.84 to 3.61 for H. macrolepidota. The mean K data are shown in table 4.9. The temporal changes for these species were also analyzed. The results of K showed that seasonal variation occurred for the three species. The highest mean K was recorded during February/April for all species, while the lowest was recorded in November/January for B. schwanenfeldii and Notopterus sp., and August/October for H. macrolepidota.
Table 4.9: The overall mean and temporal data (mean±SD) of Condition Factor (K) for three species in Pengkalan Gawi – Pulau Dula section of Tasik Kenyir from February 2008 to January 2009.
Month | B. schwanenfeldii | Notopterus sp. | H. macrolepidota |
Mean | 2.66±0.43 | 0.99±0.15 | 2.27±0.28 |
February/April | 2.82±0.53a | 1.03±0.20a | 2.35±0.39a |
May/July | 2.68±0.28ab | 0.98±0.16a | 2.22±0.21a |
August/October | 2.55±0.18ab | 0.96±0.07a | 2.17±0.19a |
November/January | 2.48±0.39b | 0.95±0.10a | 2.28±0.19a |
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