Abstract: Over the last century, riverine ecosystems have suffered from intense human intervention resulting in habitat loss and degradation and as a consequence, many fish species have become highly endangered, particular in rivers where heavy demand is placed on freshwaters. In present study three study sites were selected along the stretch of river Tons. The study was carried out during December, 2007 to November, 2009. Water samples were collected each month and brought to the laboratory and analyzed with the standard methods. Fish sampling was carried out at all the three sites on monthly basis at day as well as at night time during the course of study. Statistical correlation between fish species richness and selected hydrological attributes showed that air temperature, water temperature, pH, Dissolved oxygen and free CO2 highly influenced the fish species distribution. Total 19 species of fishes belonging to five sub-families and two orders (Cypriniformes and Perciformes) and six genera were collected from the selected study sites. The Shannon-Weiner diversity index of three different sampling indicated a strong relationship with overall species richness, showed variation and ranged from 0.036-0.173. The highest fish diversity was recorded at site-III followed by sites-II and I. The low fish diversity at site. I may be due to high altitude (1563 m) as compared to the sites II (284 m) and site-III (217 m). Hence, it may be inferred that there is inverse relationship between fish diversity and altitude of the river.
INTRODUCTION
Among the organisms, fishes are the best known species of aquatic organisms and they are the only food source harvested from natural populations. Furthermore, fishes exist at or near the top of the food chain and can serve as an indicator of a balanced aquatic ecosystem (Gorman and Karr, 1978). Fish diversity comprises of species richness (number of species in a defined area), species abundance (relative number of species) and phylogenetic diversity (relationships between different groups of species) (Gorman and Karr, 1978). Today the fish diversity and associated habitats management is a great challenge and the ability to evaluate the effects of habitat change and other impacts on the fish population required extensive surveying of the fish population before and after the change occur (Lester et al., 1996; Dudgeon et al., 2006). In the recent year, several broad scale studies have identified modification and loss of aquatic habitat as primary factor threatening the conservation of freshwater fishes and communities (Hewitt et al., 2008; Allen and Flecker, 1993). The fish diversity, community structure and species assemblages in the streams and rivers are interdependent on many abiotic and biotic factors. These factors determine the success or failure of fish species assemblages in the rivers or streams within the range of spatial distribution limits (Minns, 1989). Parameters such as species composition, species richness, abundance have been used in many studies to describe and assess fish community and diversity (Smith, 1978; Hewitt et al., 2008; Friedlander and Parrish, 1998). In the present investigation, habitat ecology, species diversity, distribution and different indices of fish diversity management were studied in Tons river, a tributary of Yamuna river, located in Uttrakhand, India to recommend conservation management measures.
MATERIALS AND METHODS
The present study was done in the Tons river which is the largest tributary of Yamuna River and flows through Garhwal region in Uttrakhand. The source lies in the 20720 feet (6315 m) high Bandrapunch mountain and one of the most major perennial Indian Himalyan rivers which confluence with Yamuna below Kalsi (30°32’N Latitude, 77°51’E Longitude) near Dehradun, Uttrakhand (Fig. 1). Three study sites were selected along the stretch of river Tons. The study was carried out during December, 2007 to November, 2009. Site-I is situated near village Bhatta (latitude N 30°26’ and longitude E 78°04’), site-II at 12 km distance from the Dehradun at Jamoliwala (latitude N 30°23’ and longitude E 78°03’) and site-III at Kandli 9 kilometers from the Dehradun, (latitude N 30°21’ and longitude E 78°00’). The location of sampling sites was documented using global positioning system. Water samples were collected each month and brought to the laboratory and analyzed with the standard method of APHA (1998). The dominant substrate material for each sampling site was determined by inspection and stroking the river bottom with a bamboo pole. The dominant substrate was expressed in with a numeric code: 0 for silt and clay, 1 for sand, 2 for gravel, 3 for pebble and 4 for cobble. Fish sampling was carried out at all the three sites on monthly basis at day as well as at night time during the course of study. For sample collection at day time, different types of gears including the cast net (1-2 m diameter with mesh size of 0.05 cm) and scoop net (mesh size of 0.25 cm) at all the study sites. During night time, fishing mosquito net was spread on the water ground and large boulders were placed over it. The net was placed close to the ground at one side and was lifted slightly up at other three sites so as to catch fishes. The represented fish samples were preserved in the 5% formaldehyde and brought to the laboratory and identified with the help of standard reference books (Talwar and Jhingaran, 1991; Day, 1978; Jayaram, 1999). Relative abundance (RA) of fish across different sites was worked out.
RA of individual species was calculated by the following formula: Number of specimens of particular species x100/Total number of specimens of all Species Distributed area occurrence = number of sites for each species x100/total number of individual s of all species.
The fish diversity indices were calculated as per standard method (Shannon and Weaver, 1963):
| H | = | Shannon-Wiener index of diversity |
| ni | = | Total No. of individuals of a species |
| N | = | Total No. of individuals of all species |
| Fig. 1: | Map showing the location of Tons river and selected study sites |
Similarity of species of fish community was calculated by using Jaccard’s measures (Southwood, 1978):
| Cj | = | Similarity between any two zones a and b |
| j | = | No. of species common to both zones a and b |
| a | = | No. of species at zone a |
| b | = | No. of species at zone b |
| if Cj | = | 1= complete similarity |
| 0 | = | Complete dissimilarity |
RESULTS
Physico-chemical parameters: Statistical correlation between fish species richness and selected hydrological attributes ( air temperature, water temperature, pH, dissolved oxygen, free CO2 , total hardness, nitrate, phosphate, silicate) indicated (Table 1) that air temperature, water temperature, pH, Dissolved oxygen and free CO2 highly influenced the fish species distribution.
Based upon the present investigation, two major types of fish habitats have been identified along the selected stretch of the river (Table 2).
Species diversity, abundance and distribution of fish community: Total 19 species of fishes belonging to five sub-families and two orders (Cypriniformes and Perciformes) and six genera were collected from the selected study sites.
| Table 1: | Correlation coefficient (r) of fish species with different abiotic parameters |
| **Correlation is significant at the 0.01 level (2-tailed), *Correlation is significant at the 0.05 level (2-tailed) | |
| Table 2: | Details of geomorphological attributes and fishing methods involved of Tons river |
Fish species composition recorded during the present investigation is documented in Fig. 2 and genus wise fishes recorded at three sites are presented in Fig. 3. Site wise percentage composition and distribution area of occurrence and IUCN status of fishes is documented in Table 3.
| Fig. 2: | Number of individuals of different species reported in the all three study site during 2007-2009 from Tons river |
| Table 3: | Species abundance and IUCN status of species reported during 2007-2009 in the Tones River |
| Vu: Vulnerable, LR-nt: Low risk near threatened, DD: Data deficient, En: Endangered, LR-lc: Low risk-least concerned | |
| Fig. 3: | Genus wise individuals reported in all study sites during 2007-2009 from Tons river |
| Table 4: | Site wise species diversity, Shannon-wiener index |
| Table 5: | Jaccard’s similarity index of fish species in different sites of Tons river |
The Shannon-Weiner diversity index of three different sampling indicated a strong relationship with overall species richness, showed variation and ranged from 0.036-0.173 (Table 4). The highest fish diversity was recorded at site-III followed by site-II and site-I. The low fish diversity at site-I may be due to high altitude (1563 m) as compared to the sites II (284 m) and site-III (217 m). Hence, it may be inferred that there is inverse relationship between fish diversity and altitude of the river.
Jaccard’s coefficient, a similarity index used to evaluate the faunal similarities between study sites showed that the fauna of sites I and III were similar (1.0) than those of sits I and II (0.93) and station I and III (0.29) site II was significant dissimilar to site I and III (Table 5).
Maximum number of individuals from the genus Barilius were recorded which includes four species of this genus Barilius. The sub-family Cyprininae emerged as the most dominant group with a total number of 8 species (genus Puntius and Tor) constituting highest percentage composition with 42% species record followed by Rasborinae (4, 21%), Nemacheilinae (3, 16%), Garrinae (2, 11%), Schizothoracinae (1, 5%) and Channidae (1, 5%) respectively (Fig. 4). The occurrence percent of genus Puntius and Barilius was 0 in the site I while Nemacheilus species showed maximum occurrence (69.20%). At site II, occurrence percent were ranged from 0-26.75 and 0-33.63 for the site III. Barilius bendelisis was found with highest percentage of occurrence as 26.75 and 33.63 % at site I and II respectively (Table 3). Among the all study sites maximum number of individuals was found of genus Barilius species whereas minimum were that of Tor species (Fig. 1). In case of sub-family Cyprininae, all the species of genus Puntius i.e. P. chola, P. ticto, P. sarana sarana, P. phutunio and P. chonchonius were reported at site-II and III while only P. chonchonius was reported at site-I. Among genus Tor, T. putitora, T. tor and T. chelynoides were reported at site-II, Tor tor, Tor putitora at site-III and Tor putitora at site-I (Fig. 2).
| Fig. 4: | Percentage composition and abundance of fish species recorded at three selected sites during the two year period from Dec., 2007-Nov., 2009 |
Among sub-family Garrinae, Garra lamta was reported only at site-I while Garra gotyla gotyla was recorded at site-II. The sub-family Schizothoracinae represented by Schizothorax richardsonii was recorded only at site-I. In case of sub-family Nemacheilinae, N. montanus and N. rupicola were reported at sites I and III while N.carletoni was reported only at site-III. Among sub-family Channidae, only Channa punctatus was found to be reported at all the sites (Fig. 2).
At site-I, Nemacheilus montanus was dominant and Nemacheilus rupicola was abundant and were recorded throughout the year, with maximum occurrence during winter season. Other species P. conchonius, T . putitora, G. lamta, S. richardsonii and C. punctatus were reported occasionally. At site-II, B. bendelisis and C. punctatus were dominant species while B.vagra, P. chola, P.conchonius, T. putitora, T. chelynoides and N. montanus were recorded in abundance. B. barna, B. barila, P. phutunio, P. ticto, P. sarana, T. tor, G. gotyla were recorded occasionally. Almost all the species showed maximum abundance during winter season along with P. conchonius which was collected in good numbers during post-monsoon season.
At site-III, B. bendelisis and T. putitora were dominant species while B. barila, B. vagra, P. chola, P. ticto, N. montanus and C. punctatus were abundant species. B.barna, P. sarana, P. phutunio, P.conchonius, T. tor, N. rupicola and N. carletoni were reported occasionally. Channa punctatus showed maximum abundance during post monsoon season while all the other species showed maximum abundance during winter season.
Conservation status: Out of the 19 species of fishes collected from study area the genus Barilius was collected in good numbers and was considered in the IUCN category of low risk least concerned (LR-nt), while the genus Tor, Channa and Nemacheilus were moderately collected and were considered low risk near threatened. The species of genus Schizothorax and Garra were collected occasionally and in small number thus they showed vulnerable (Vu) status (Table 3).
DISCUSSION
The present investigation revealed that the physical habitat variables play a key role in the distribution of fishes in the river Tons and habitat alteration brought about a threat to freshwater fish fauna. It was also observed that among physico-chemical attributes, air temperature, water temperature, dissolved oxygen, pH and free CO2 are positively correlated with fish assemblages and influenced the fish distribution. Similar pattern was observed by Gorman and Karr (1978), Stalnaker (1979), Bovee (1982) and Baltz et al. (1987) who attributed the fish assemblage structure variation on various factors like river depth, velocity of water, water temperature, substrate and water quality. Recently significance of habitat variables was endorsed by Shrestha et al. (2009) who suggested that various water quality parameters must be watched regularly to keep the aquatic habitat favorable for existence of fish. The present study is the first of its kind for the river Tons on fish diversity and conservation priority. The study depicted presence of 19 species contributing about 55.88% of total fish diversity published from western Doon valley (Mehta and Gupta, 2007) and about 40.4% of total fish species from entire doon valley (Singh, 1964). During the present investigation, Barilius species has emerged as the most abundant group. This finding was in accordance to the findings of Uniyal (2007) and Husain (1995) who reported the Barilius species as the most abundant group with a total catch of 35% and Negi et al. (2007) who reported the cypriniformes as the most abundant order. Recently Negi and Negi (2010) reported cyprinids as the most dominant group during the study of the fish assemblage structure in the streams of Kumaon Himalayas of Uttrakhand state. During the present findings, a total of 19 species of fish have been reported from three selected sites of Tons river. Among which the maximum diversity was recorded from site II and site III whereas least number of species were recorded from site I which clearly indicates that there is negative co-relation between altitude and fish species diversity. The present finding favors the concept of Tripe (1998) and Reves-Gavilan et al. (1996). According to them the altitude of the stream or the river shows inverse relationship with fish biodiversity level. The more the altitude the less will be the evenness and abundance of fish species. According to Nautiyal (2001) fish assemblage is less at the origin because of high water current but is more towards the confluence of the river as the water content is more at that point. Besides this, he also suggested that the fish species abundance and distribution is highly influenced by altitudinal and longitudinal zonation of any particular river system. FAO (1985), Bayley and Li (1994) and Grando (2000) also documented that fish communities in riverine system typically follow a pattern of increasing species richness, diversity and abundance from upstream to downstream.
CONCLUSION
Species diversity in different sampling sites indicated that altered habitat and high altitude support less fish species while variety habitat like shallow pool and deep pools are the primary habitats contributing to the maximum diversity, sub-family Cyprininae emerged as the most dominant group therefore, protection of these particular habitats is recommended for conservation and management of the fish biodiversity.
ACKNOWLEDGMENT
Authors are thankful to Head Department of Zoology and Environmental Sciences, Gurukula Kangri University Haridwar for providing laboratory facility to conduct this work.