BIOLOGIA (PAKISTAN) 2014, 60 (1), 73-80 PKISSN 0006 – 3096 (Print)
ISSN 2313 – 206X (On-Line)
Temporal variations in Commercial Fish Community of a Floodplain of the River Ravi, Pakistan *ALTAF HUSSAIN1, ABDUL QAYYUM KHAN SULEHRIA2, MUHAMMAD EJAZ1, ASMA MAQBOOL1 & MUHAMMAD RAMZAN MIRZA1 1
Department of Zoology, GC University, Lahore, Pakistan Department of Zoology, Govt. Islamia College, Civil Lines Lahore, Pakistan
2
ABSTRACT Temporal distribution of commercial fish community of a floodplain lake situated on River Ravi near Balloki Head Works was investigated. Survey was conducted by taking monthly samples from August 2012 to May 2013. In total, 1703 fishes were collected and identified which belonged to 19 species, 14 genera, 8 families and 7 orders. Cypriniformes was the most abundant order with a largest number of representatives. The most abundant species were Labeo rohita (229), Wallago attu (225) and Cirrhinus mrigala (214) whereas Xenentodon cancila was present in lowest number (5). Shannon- Weaver index (H) was highest in December (2.67581) and lowest in May (1.80945), Simpson index of dominance (D) was highest in May (0.21893) and lowest in December (0.08306), Simpson index of diversity (1-D) was highest in December (18.9169) and lowest in May (18.781). Species richness (SR) was maximum in February (3.4206) and minimum in April (2.1722) while Species evenness (E) was highest in August (0.95691) and lowest in May (0.82351). Key words: Floodplain, River Ravi, Balloki Headworks, Density of fishes, Diversity of fishes.
_______________________________________________________________________________________ INTRODUCTION Floodplains of many tropical rivers are receiving scientific as well as conservational interest as they are essential feeding, breeding and rearing places of a majority of freshwater fish species (Keddy, 2010). Floods provide connections between lake and main river channel. Periodic flooding facilitates nutrient exchange between the river and floodplain, helps in sediment deposition in floodplain habitats, and homogenizes fish communities by allowing mixing of river and floodplain water (Miranda, 2005; Schramm & Eggleton 2006). Floodplains inundated during monsoons are nutrient rich and play a significant role as nurseries for many larvae and juvenile fish species (Ramberg, et al., 2006; Lindholm, et al., 2007). Floodplains generally accumulate and store nutrients during low flow seasons and release these nutrients into the main river during high flows and floods. Floodplains also help in decreasing the impacts of seasonal flood events by spreading large amounts of water over large spatial areas (Walbridge, 1993). Some fish species use floodplain channel as spawning grounds during high water flow periods whereas juveniles utilize them as nursery grounds (Shaeffer & Nickum, 1986; Copp, 1989). Fish species richness in floodplain lakes is positively correlated with degree of flooding and with linear distance between the floodplain and the main river channel. Improved connectivity between mainstream and floodplain habitats and increased *Corresponding author:
[email protected]
inundation of floodplains has been shown to increase some fish populations (Rood, et al., 2003). Changes in the natural flow regimes of main rivers and alterations to the floodplain channel mainstream connectivity may lead to decreased diversity of fishes in river ecosystems. Disrupting connections between river and its floodplain channel may impact fish communities by disrupting food, spawning and rearing resources required by riverine fish populations (Bayley, 1995; Grift, et al., 2001). Seasonal inundations are supposed to increase the natural productivity and animal diversity of floodplain ecosystem (Junk, et al., 1989). Seasonal inundation has been linked with the increased yield of fishes in riverine systems (Bayley, 1991; Agostinho & Zalewski, 1995). The growth of fish in floodplain is fast and strongly related to flood season (Dudley, 1972). Growth of fish can vary significantly between years and is correlated with flooding intensity and duration (Halls, 1998; Halls, et al., 1999). Few studies are available for the spatiotemporal distribution of adult fishes in floodplain in relation to their improved spawning behaviour. As demand for water resources has increased, the importance of floodplain for fish spawning and juveniles nursery has also been increased to a large extent. In the present studies, the importance of floodplain of River Ravi near Balloki Head Works was investigated for density and diversity of cultureable fishes. The floodplain on River Ravi is a highly dynamic environment. The main emphasis of
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this study was to explore the importance of floodplain for the development of aquaculture in Pakistan. MATERIALS AND METHODS Study area The floodplain under study is situated on the River Ravi near Balloki Headworks in District Kasur, Punjab Pakistan, and 65 Km away from Lahore. It is lying at a Latitude: 31° 11' 25" North, and at Longitude: 73° 52' 40" East. The total area of the floodplain, under study, comprises about 8.6 Km. It has distinct tropical climate with a marked monsoonal effect with an average rainfall of 52.01mm, humidity 70.40% and average atmospheric temperature ranges from a minimum of o o 5 C in winter to a maximum of 50 C in summer. Water level varies in different months of the year, being highest in summer (May to August) and lowest in winter (October to April) every year. Fish Sampling Fish fauna of the study area was collected on monthly basis from August 2012 to May 2013, using a variety of fishing nets like cast net, drag net and gill nets of various mesh sizes (Bhat, 2003). The samples were fixed in 10 percent buffered commercial grade formalin. Samples were packed separately with appropriate labels indicating the date, time, locality, and the name of collector. Sampling in the months of June and July was not done, due to ban imposed by Fisheries Department on fishing activities in breeding season. This corresponded to our temporal scale of analysis. Identification and Classification The specimens were identified and classified on the basis of morphometry using the standard keys (Mirza & Sharif, 1996; Mirza & Sandhu, 2007). Diversity Indices and Cluster Analysis The data was analyzed by using the Shannon-Weaver index (H’), Simpson index of dominance (D) and Simpson index of diversity (1-D) to calculate the species diversity. To study the distribution of fish species and type of food chain, the species richness (SR) and evenness (E) was calculated. Cluster Analysis was performed to observe and sort the different sets of species. Species Abundance curve was plotted to know the most abundant and rare species present in the specific locality (Sulehria et al., 2009a, 2009b). RESULTS The fishes collected from the reservoir are shown in Table 1. Total number of fishes varied widely during
BIOLOGIA (PAKISTAN)
current period of study in this reservoir. In total, 1703 fish specimens were collected which belonged to 19 species, 14 genera, 8 families and 7 orders (Table 2). Labeo rohita showed the highest catch with a total number of 229 (13.5 ± 4.3 %) specimens. Wallago attu showed the second largest catch with a total number of 225 (13.2 ± 1.8 %) fishes and Cirrhinus mrigala stood at number three with a total count of 214 (12.6 ± 3.6 %) throughout the period of study. Xenentodon cancila showed the lowest catch of only 5 (0.29 ± 0.3 %) fishes during the whole period of studies. No species numerically dominated in the present reservoir. Species wise order of catch from highest to lowest is Labeo rohita˃ Wallago attu˃ Cirrhinus mirigala˃ Labeo calbaso ˃Oreochromis mossambicus ˃Sperata sarwari˃ Cirrhinus reba˃ Notopterus notopterus˃ Channa marulia˃ Channa punctata˃ Catla catla˃ Labeo boga˃ Cyprinus carpio˃ Chitala chitala˃ Ctenopharyngodon idella˃ Hypophthalmichthys molitrix˃ Mastacembelus armatus˃ Mastacembelus pancalus˃ Xenentodon cancila. It was observed that large number of fishes were present during winter i.e., in the months of low water level (From October to December) than summer i.e., the months of high water level. The results showed that highest catch of 309 fishes was recorded in the month of December whereas the lowest catch of 26 was recorded in the month of May (Table 1). Month wise relative percentage of fishes is shown in figure 1. Highest percentage of fishes (18%) was found in the month of December. In October 14% fishes were found. Lowest percentage of fishes (1.5) was found in May. The contribution of some exotic fishes, Hypophthalmichthys molitrix, Ctenopharyngodon idella and Oreochromis mossambicus has also been shown during the present period of studies, which confirmed the overflow of water from River Ravi during the flooding season. Numerically the most abundant order was Cypriniformes represented by 47.37% of the total individuals followed by Osteoglossiformes, Siluriformes, Channiformes, Mastacembeliformes was represented by 10.53% and Biloniformes and Perciformes were represented by 5.26% respectively (Table 2, Figure 2). Taxonomically the most abundant family was Cyprinidae which was represented by six genera, followed by Notopteridae represented by two genera and Bagridae, Siluridae, Beloninidae, Channidae, Cichlidae and Mastacembelidae each represented by one genera. The rank abundance curve of fish species was plotted to display the relative species abundance of the fish species collected (Figure 3). According to this Labeo rohita (229) stood first in rank i.e., found in large number, Wallago attu (225)
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stood second and Cirrhinus mirigala (214) was third. According to this curve Xenentodon cancila (5) was present at last stage in rank with the lowest number. The species rank abundance plot showed a greater proportion of intermediate abundant species. In order to show the sampling similarities in different species, the data was subjected to Multivariate Cluster Analysis for preparation of Dendrogram using Euclidian distance. The results (Figure 4) showed that at Eucladian distance of almost 16, all the fish species were arranged in five different groups on the basis of their abundance and similarities. Labeo boga, Cyprinus carpio, Notopterus notopterus, Ctenopharyngodon idella and Hypophthalmichthys molitrix formed the first group with less number of fishes. Xenentodon cancila, Mastacembelus armatus and Mastacembelus puncalus formed second group in this particular reservoir. Lowest number of fishes was found in this group. Xenentodon cancila was represented by only 5 individuals throughout the year. Catla catla, Channa marulia, Channa punctata, Chitala chitala and Cirrhinus reba formed the third group with moderate number of fishes in the present studies. Labeo calbaso, Sperata sarwari and Oreochromis mossambicus formed the fourth group. Labeo rohita, Wallago attu and Cirrhinus mrigala formed the last cluster with highest number of fishes in the present studies. The value of Shannon-Weaver index was highest in December (2.67581) and lowest in May (1.80945). Similarly Simpson index of dominance (D) was highest in May (0.21893) and lowest in December (0.08306). Simpson index of diversity (1D) was highest in December (18.9169) and lowest in May (18.781). The species richness (SR) was highest in February (3.4206) and lowest in April (2.1722) and species evenness (E) was highest in August (0.95691) and lowest in May (0.82351) (Table 3). The total discharge of water (Cusecs) in River Ravi at Balloki Headworks was measured by Flood and Drainage division, Punjab Irrigation Department, Lahore. The highest discharge was in August (45370 Cusecs) whereas the lowest discharge was in the month of January (6614) in the River Ravi at Balloki Headworks (Figure 5). DISCUSSION Seasonal fluctuations of water level in floodplains seemed to influence the fish composition in the floodplain. The greater number (309) of individual fish caught and species composition were observed during the low water season i.e., in the month of December. The lowest catch (26) was
75
recorded in the month of May when water level started to increase with the onset of melting of ice on mountain caps. The water level was highest in the month of August when floods were at their peak during Monsoon in Pakistan. In present studies an inverse relationship was seen between the water level and the total number of fishes caught (Figure 5). Boujard (1992) reported that the behaviour of freshwater fishes from French Guiana was supposed to be strongly influenced by seasonal variations in water level. Renato, et al. (2000) studied that fish abundance and species richness at the upper Juru´a were greater in the dry season. During that season, fishes might be concentrated due to the low water level being more easily caught by gillnets whereas during high water level, the fishes probably dispersed along the inundated floodplain. Goulding, et al., (1988) also reported the similar results for other Amazonian Rivers. In general the amount of total commercial fish catches inversely followed the pattern of water fluctuation in the floodplain. Flood water recession reduced the availability of aquatic habitats for fish resulting in fish densities and biotic interactions (Winemiller, 1989; Rodr’iguez & Lewis, 1994; 1997). Our floodplain is situated on River Ravi near Balloki Headworks. During monsoon when water level was highest in river, water flowed in the adjacent floodplain areas. From July to August the floodplain was well connected with the river. This allowed the influx of large number of fishes from river to the present floodplain. Miranda (2005) hypothesized that lakes with higher degrees of connectivity (i.e., greater flooding) are expected to contain a lotic and lentic species that periodically mixed during flood pulses, whereas lakes with lower degrees of connectivity would contain mostly lentic species. There was some evidence of this possibility in the present study. For example, our Major carps Labeo rohita, Cirrhinus mrigala, and Catla catla and the Chinese carps Hypophthalmichthys molitrix and Ctenopharyngodon idella are mostly lotic species and are in the habit to lay their eggs in running water (Mirza, 2004). The presence of these fishes in lentic system indicated that these fishes migrated from nearby river i.e., lotic system through Flood pulse. Relative % age representation of fishes in the monthly catches showed that the different species of fishes were present in moderate to large number. Diversity indices were found highest in low water level seasons i.e., from October-December. Highest value of Shannon-Weaver index (H), and Simpson index of diversity (1-D) are an indication of greater distribution of fishes in the months of October, November, and December. Highest value
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of species richness (SR) in the month of February expressed high food chain. Highest value of species evenness in August represented even distribution of fishes in this month. These results showed that the flood plain was rich in fish communities and all the species were evenly distributed throughout the floodplain. The rank abundance curve expressed that the fish fauna was diverse in this specific reservoir. The curve had relatively steep slope. It further showed the Labeo rohita, Wallago attu and Cirrhinus mrigala were the most common species represented by 13.44%, 13.21% and 12.56% respectively. Similarly Xenentodon cancila is a rare species with least representation of only 0.29% only. Lowe-McConnell (1987) said that seasonal environments tended to have diverse fish communities with a few dominant species. The high numerical dominance of some fish species in the present reservoir might be related to seasonal disturbances, such as large and unpredictable variations in water level during May to June and temperature difference that favoured some species better adapted to such conditions. Similar results had been reported by Jepsen (1997). The Multivariate Cluster Analysis performed for the sampled fishes had arranged them in five different groups (Figure 4). There might be different reasons assigned to these groupings, including the similarity of feeding, breeding and living habits. There are different factors which were responsible for controlling the distribution and diversity of fishes in the flood plains. Rainfall was
BIOLOGIA (PAKISTAN)
one of them which played a significant role in deceasing and increasing water level in the Flood plain. The hydrological cycles of the lake also affected the distribution and abundance of fishes in floodplains. The hydrological cycle in Pakistan mostly started in May which raised the water level in rivers, thereby filling the lake quickly. The maximum level reached in August when the floods were in full swing. After that the water level began to fall slowly and reached to minimum in December. There was no increase in water level from December to May. Additionally, a number of other factors also played their role in the alteration of ecological conditions of the reservoir during the last two decades. These were the increased sewerage/industrial pollution, sedimentation, over-fishing and introduction of exotic species in the reservoir. Discussions with some fishermen revealed that the population of these fishes had drastically declined during the last decade or so, owing to the increasing level of pollution in River Ravi. Apparently, these factors individually or in concert manner may have caused the changes in ecology of the flood plain resulting in the changes in fish fauna and commercial catches (Mirza, et al., 2012). The fishing contractor was solely responsible for the exploitation of the fisheries resources of the water body for the period leased out. It was observed that in order to maximize his profits, the fishing contractor tried to scoop maximum quantities of fish during the year especially in the months of low/dead water level which decreased the monthly catch in preceding months.
Fig., 1: Month wise relative % of fish species in the flood plain during the present studies.
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Table 1: Density and diversity of fish species in a flood plain of River Ravi. Species
Au
S
O
N
D
J
F
Mr
Ap
Ma
Total
% age
MEAN
STDV
VAR
SEM
Chitala chitala
0
3
7
18
20
15
17
3
0
0
83
5
8.3
8.27
68
2.6
Labeo rohita
25
24
30
35
45
33
17
10
7
3
229
13.5
22.9
13.5
183
4.3
Labeo calbaso
15
21
21
20
25
21
16
12
10
1
162
9.51
16.2
7.07
50
2.2
Labeo boga
10
8
4
5
7
6
3
7
0
0
50
2.94
5
3.3
11
1
Catla catla
10
8
6
7
10
9
6
4
2
0
62
3.64
6.2
3.36
11
1.1
Cirrhinus mrigala
15
18
25
30
43
30
21
20
9
3
214
12.6
21.4
11.4
130
3.6
Cirrhinus reba
15
11
17
15
17
15
3
2
0
0
95
5.58
9.5
7.34
54
2.3
Cyprinus carpio
6
3
5
4
7
6
4
3
3
1
42
2.47
4.2
1.81
3.3
0.6
Sperata sarwari
11
7
15
20
25
17
10
8
5
5
123
7.22
12.3
6.75
46
2.1
Wallago attu
20
23
25
28
30
27
23
20
19
10
225
13.2
22.5
5.72
33
1.8
Xenentodon cancila
0
1
0
0
3
0
1
0
0
0
5
0.29
0.5
0.97
0.9
0.3
Channa marulia
10
13
8
9
10
8
7
6
3
1
75
4.4
7.5
3.5
12
1.1
Channa punctata
15
15
10
6
15
3
3
2
2
1
72
4.23
7.2
5.96
36
1.9
Mastacembelus armatus
0
2
3
5
5
0
1
1
0
0
17
1
1.7
2
4
0.6
Mastacembelus pancalus
0
0
0
1
5
3
2
3
0
0
14
0.82
1.4
1.78
3.2
0.6
Total
195
188
241
222
309
206
145
108
63
26
1703
100
170.3
Percentage
11
11
14
13
18
12
9
6.3
4
1.5
100
Au=August; S=September; O=October; N=November; D=December; J=January; F=February; Mr=March; Ap=April; Ma=May; STDV = Standard Deviation; VAR = Variance; SEM = Standard Error of Mean.
Table 2: Relative % representation of fish orders in present floodplain Relative % No.
No. Of
No. of
No. of
families
genera
species
No. Of Orders
representation of order
1
Osteoglossiformes
1
1
2
10.53
2
Cypriniformes
1
6
9
47.37
3
Siluriformes
2
2
2
10.53
4
Beloniformes
1
1
1
5.26
5
Channiformes
1
1
2
10.53
6
Perciformes
1
1
1
5.26
7
Mastacembeliformes
1
1
2
10.53
Total
7
8
14
19
100
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A. HUSSAIN ET AL
BIOLOGIA (PAKISTAN)
Table 3: Seasonal fluctuations of diversity indices, Species richness and Species evenness of fish species in the present studies.
ShannonMonths
Weaver Index (H)
Simpson
Simpson
Index of
Index of
Dominance
Diversity
(D)
(1-D)
Species Richness (SR)
Species Evenness (E)
Aug.12
2.52534
0.08865
18.9113
2.4653
0.95691
Sep.12
2.57466
0.08725
18.9127
3.0555
0.90874
Oct.12
2.54227
0.10081
18.8991
3.0925
0.87956
Nov.12
2.58898
0.091
18.909
3.1362
0.89572
Dec.12
2.67581
0.08306
18.9169
3.1413
0.90876
Jan.13
2.48265
0.10001
18.8999
3.0058
0.87626
Feb.13
2.48652
0.10146
18.8985
3.4206
0.86027
Mar.13
2.36139
0.11649
18.8835
2.799
0.89478
Apr.13
2.03085
0.16402
18.8359
2.1722
0.88198
May.13
1.80945
0.21893
18.781
2.4554
0.82351
Fig., 2: Percentage contribution of different orders during the current period of study
Fig., 3: Rank abundance curve of fish species in a flood plain during the period of studies.
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79
REFERENCES
Fig., 4: Dendrogram of fish species in a flood plain during the period of studies.
Fig., 5: Seasonal fluctuations in the Number of fishes/Month and total discharge (Cusecs) in the present studies. Increasing human population and urbanization are continuously posing threats to the already fragile fisheries resources. Strengthening of existing facilities and proper implementation of fisheries rules are needed to increase the natural productivity of the floodplains. It is recommended that further studies regarding the controlling factor should be carried out to increase the potential of fish production in the present floodplain of River Ravi near Balloki Headworks.
ACKNOWLEDGEMENTS The authors are thankful to Fisheries Department Punjab, Lahore for providing help in sampling and Punjab Irrigation Department for providing the valuable flood data.
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