The Western Ghats of India is a UNESCO World Heritage Site and is one of the
eight “hotspots” of biological diversity in the world. It is also referred
to as the “Great Escarpment of India”. This paper provides information on
the diversity of freshwater fish fauna of six river systems of the southern
Western Ghats. The study area has been identified geographically using a GPS,
and the respective topographic map has been digitized using ArcGIS software.
The fish fauna were collected from various streams and rivers using cast
nets, dip nets, gill nets and drag nets. Among the 31 georeferenced sites
sampled from the rivers of the southern Western Ghats, a total of 64 species,
belonging to 6 orders, 14 families and 31 genera, were recorded. Among them,
the order Cypriniformes was dominant, with 3 families, 18 genera and 49
species (76.6 %). Principal component analysis and cluster analysis were
performed to express the contribution of the variables and their influence on
the species diversity. Interestingly, of the 31 sites, Thunakadavu stream,
Gulithuraipatti, Athirapally,
Naduthotam, Nadathittu, Mullaithodu, Thonanthikla, Noolpuzha and
Sinnaru exhibited
high variation in species diversity. Nearly 15 species were found to be
threatened in the Western Ghats.
The Western Ghats of India is a UNESCO World Heritage Site and is one of the eight “hotspots” of biological diversity in the world. It is also known as the “Great Escarpment of India” (Myers et al., 2000). The range of the Western Ghats runs from north to south along the western edge of the Deccan Plateau, and separates the plateau from a narrow coastal plain, called Konkan, along the Arabian Sea (Fig. 1, Bhavani river system). Of a total of 39 World Heritage Sites in India, which include national parks, wildlife sanctuaries and reserve forests, 20 are in Kerala, 10 in Karnataka, 5 in Tamil Nadu and 4 in Maharashtra; these have to be protected and conserved. The Western Ghats of India has rich freshwater fish fauna with a high level of endemism (Dahanukar et al., 2004). At present, a major part of the faunal diversity of the Western Ghats is threatened by human activities and invasive species (Dahanukar et al., 2004). Hence, knowledge of the diversity and distribution of the fish fauna is essential for designing and implementing conservation strategies. However, data on the fish fauna of the Western Ghats have limitations as most of the rivers have not been surveyed extensively with georeferenced data, and checklists for individual rivers are not available.
Location of collection sites in six river systems.
The history of Indian freshwater fish fauna goes back to Hamilton (1822), who
studied fish fauna found in the river Ganges and its tributaries.
Documentation and listing of fish fauna from different parts of India was
mainly carried out by Jerdon (1848). A comprehensive and authoritative
account on the freshwater fish fauna has been provided by Day (1865, 1871,
1878). Further investigations on the freshwater fish fauna of India,
especially in the Western Ghats, were initiated by Hora (1921, 1937, 1941,
1949) and Hora and Misra (1938), and Hora also enunciated the Satpura
Hypothesis. Silas (1951) listed 25 fish species from the Anamalai Hills and
10 species from the Nelliampathi Hills. His study extended the distribution
of several species earlier known only from the central division of the
Western Ghats to the southern division beyond the Palghat Gap. These led to
new descriptions, initiating elaborate discussions on the endemism and other
zoogeographical relevance of the area, and several new taxa were added from
Kerala during this period. Studies on the endemic fish fauna from various
streams and rivers in the Western Ghats mountain range have been compiled.
Fish diversity in selected streams in northern Karnataka (Arunachalam et
al., 1997) and the central Western Ghats (Arunachalam et al., 2000) has been
reported. Manimekalan and Das (1998) described a new species,
Study site and their habitat characteristics.
Velocity (m s
List of freshwater fauna recorded during the present study.
Continued.
The study area has been identified geographically (the latitude and longitude coordinates) using a GPS, and the respective topographic map has been georeferenced and digitized using ArcGIS 9.3 version software. Fish fauna were collected using cast nets, dip nets, drag nets and gill nets of different mesh sizes ranging from 8 to 22 mm. Proper care was taken to avoid damage to the specimens during collection. A total of five specimens from each species were collected from the georeferenced sampling locations, and fish fauna were photographed before being preserved in formalin so that they could be photographed in their original colour. Further, for smaller samples, specimens were preserved in 10 % formalin, and for larger samples, formalin was injected into the abdominal cavity so that the internal organs could be preserved well for further taxonomic studies. The specimens were tagged, reference numbers were given for specimen identification, and they were transported to the lab. The species were identified based on the key given by Talwar and Jhingran (1991), Menon and Devi (1992) and Jayaram (1999, 2010). The holotype and paratype species were examined at the Zoological Survey of India (Chennai and Kolkata) for species confirmation. Voucher specimens were made for each species and were deposited at the Biodiversity and Molecular Lab, Dept. of Environmental Sciences, Bharathiar University, Coimbatore, Tamil Nadu, India.
Water samples were collected from all the sampling stations during the post-monsoon period (February to June) at a depth of 10 cm. Water quality analyses such as pH, conductivity, turbidity, total dissolved solids (TDS), resistivity, salinity, dissolved oxygen (DO), and water temperature were done as per the regulations of APHA (1995). Field analysis of the samples was done using a portable water analyzer (X tech, Nagman Instruments Electronics, India) (Gurumurthy and Tripti, 2015; Thomas et al., 2015; Anushiya and Ramachandran, 2015).
To quantify species diversity, a number of indices were applied. To measure
the species diversity (
The fish fauna were surveyed from the streams and rivers of the southern Western Ghats. The collection sites were selected based on the earlier faunal distribution published in literature. The Western Ghats is a mountain range that runs almost parallel to the western coast of the Indian peninsula. The study sites and their characteristics are recorded and presented in Table 1 and Fig. 1. In the present work, a total of 31 sites of six river systems of the southern Western Ghats were studied, of which a total of 64 species, belonging to 6 orders, 14 families and 31 genera, were recorded (Table 2). Among them, the order Cypriniformes was dominant, with 3 families, 18 genera and 49 species (76.6 %), compared to other orders (Figs. 2, 7).
Among the 31 sampling locations, high species diversity was recorded at
Sinnaru of the Cauvery river system (
Indices of diversity of fish fauna and respective altitudes of six river systems.
Species similarity between the sites was very low among 31 sites of six river systems. Cluster analysis exhibited similar species composition between the sites (Table 4, Fig. 6). A total of five clusters were grouped, which clearly demonstrate the similarity of species composition among the sites. The cluster group separation is based on the following reasons: (1) rare species forms, (2) low water temperature and (3) prevalence of human disturbances.
Representation of fish fauna orders among the six river systems.
Species diversity among 31 sites.
Species richness among 31 sites.
Species abundance among 31 sites.
Cluster dendogram expressing the dissimilarity.
Water quality parameters are recorded and presented in
Table 6. It is found that the parameter values lie within the IS:
10500 Permissible limits (Table 6 of BIS, 2012). The selected sites of the
Western Ghats has a water pH ranging from 6.5 to 8.5. A pH of 9 was recorded
at Kadapilliyarthittu of the Cauvery river system, and 7.2 was recorded at
various sites like Anjurily, Athirappilly and Urilikal. A minimum
conductivity value of 27.8 mS was recorded in the Chalakudy river system,
and a maximum conductivity value of 85.2 mS was recorded at Noolpuzha of the
Nugu river system. Total dissolved solids (TDS) are a measure of inorganic
salts dissolved in water. These dissolved solids come from both natural and
human sources. Mitchell and Stapp (1992) have suggested that changes in TDS
concentrations can be harmful. If TDS concentrations are too high or too low,
the population of aquatic life can be limited. Thenkasithodu of the Periyar
river system witnessed a low value of TDS content of 13.7 mg L
Stream habitat was measured in dimensions like length, width, depth,
substratum and current. Large proportions (
Species composition among the 31 sites.
For the present study, the fish species diversity and the habitat quality
assessments of the river systems have been considered as major criteria.
The results exhibit that flora and fauna flourish in the study area. This proves that the habitat provides food and shelter suitable for the
fish fauna and other aquatic organisms. The habitat assessment of the study area
shows that there are four habitat types (pool, riffle, run and glide) with six
substratum types (fine sand, debris, silt, bedrock, gravel, rubble and
boulders). The shoreline also has a sandy border and a strong rigid bottom made up of rocks, which
creates a good habitat for the aquatic organisms. Moreover the water
quality, substratum type and vegetation provide a good and healthy habitat
and high food resource availability, which plays a key role in species
diversity. The river habitat is utilized by tribal people for catching
fish for their source of protein food. In the present study, the substratum types of rubble and boulders were dominant,
representing 80 % in Mullaithodu of the Periyar river system. At Anjurily of the Periyar
river system, gravel is the dominant substratum, representing
70 %. Moreover, substratum types like sand and silt are equally
represented in all the study sites. Debris is the biological matter that
occupies a major part the stream habitat and is important for providing good shelter and
a feeding habitat for the fish fauna. Mostly bottom feeders like
Distribution and abundance of fish fauna of six river systems.
Continued.
Water quality of 31 study sites of six river systems.
Contribution of the variables (%) after varimax rotation for habitat characteristics.
Stream width and volume were high at Belikoondu of the Cauvery river system
(80 m, 80 000 m
Principal component analysis was used to illustrate the influence of the
variables and its importance for the ecological structure of the river system
and the fish species. The various habitat characteristics, like water
quality, channel morphology and the substratum type, influence the species
distribution. Factors like altitude (6.940), area (21.449) and volume
(58.428) influence the species diversity (Table 7). All other characteristics
play a supportive role in expressing the variations among the study sites.
Based on the contributions, study sites like Belikoondu, Kallampalayam,
Sorrakottaodai, Anjurily, Thenkasithodu, Belemeenthurai, Kovaikutralam,
Naduthotam, Nadathittu, Kadapilliyarthittu and Sinnaru exhibit more
variations. The results obtained conclude that altitude plays a major role in
species diversity and species abundance, which supports the proposed theory
that diversity changes with altitude on mountainsides, being lowest at higher
elevations (Colinvaux, 1930). The present findings support the above theory
as the results express that species diversity and abundance are low at high
altitudes. Among the 31 sites, high species diversity was recorded at Sinnaru
of the Cauvery river system (
Rajan (1955) studied the fish fauna from the Moyar river system and reported
48 species. Manimekalan (1998) reported 38 species in the Mudumalai wildlife
sanctuary. Manimekalan stated that species like
Silas (1951), in his faunal account, discussed the extension of the range of
The Periyar River originates near Moolavaigae and reaches the Mullaperiyar
reservoir, located in the premises of Periyar Tiger Reserve, which is one of
the most biodiversity-rich zones in the southern Western Ghats (Silas, 1950,
1952; Kurup et al., 2004). Earliest studies on the fish fauna of the PTR date
back to 1948, when Chacko (1948) listed 35 species from the Periyar Lake,
including the critically endangered small-scale
Smith and Smith (1990) stated that habitat selection of the fish fauna is
influenced by the body structure, by food and shelter and by physiological
processes. Moreover the fish adapt and respond to the characteristics of the
rivers and streams, thereby helping the survival of the fittest. Hence it is
reliable information that the micro- and macrohabitat play a key role in the
morphology and physiological characteristics and modifications of the
species. The fish prefer habitats where the nature of the river or stream
substratum type is a muddy bottom with debris; this increases high species
richness of the bottom feeders. Odum (1945) stated that the flow of the water
in the channel is an important factor controlling the distribution of fish
fauna; species like
Conservation of India's vast and diverse aquatic genetic resources is essential to maintain ecological as well as socio-economic equilibrium (Lakra et al., 2007). Fisheries and aquaculture have a promising role to play in social development by providing nutritional security for the Indian population and contributing to the economic advancement of farmers and fishery workers (Ambili, 2013). The concept of fish conservation is not new to India. Fishing was prohibited during the third Chatturmass (July–October) to protect the pre-spawning brood stock and juveniles. King Ashoka's prohibition period extended up to the middle of November. Renowned fisheries taxonomist Francis Day drew the attention of the government of India to the large-scale slaughter of fish and pleaded for urgent conservation measures. After persistent pressure, the Indian Fisheries Act was enacted in 1897. Destructive fishing methods, the creation of fixed engines (dams, weirs etc.) for catching fish and the use of small sized nets were banned by the law. The main threats impacting freshwater biodiversity in the Western Ghats include pollution (urban and domestic pollution ranking as the worst threats, followed by agricultural and industrial sources of pollution), residential and commercial development, dams and other natural system modifications, invasive species, agriculture and aquaculture and energy production and mining (IUCN, 2015). The anthropogenic perturbations to fresh water systems over the past years have escalated to enormous proportions, and it is estimated that about 3000 species will become extinct within the next 20 to 30 years (Das, 1994; Prasad, 2010).
The threat to the endangered fish species from our aquatic ecosystem can be minimized by employing both preventive and protective measures. The preventive measures may include removal of causative factors and provision of suitable legislation. The protective measures would include identification of suitable areas to declare as sanctuaries and the development of new technologies for the protection of the genetic resources of threatened and vulnerable fish species. Keeping this in view, the present investigation highlights some of the main causative factors of the decline of various fish species and some remedial measures for preserving the fish population. Degradation of aquatic systems, indiscriminate fishing of brood fish and juveniles, anthropogenic intervention, use of explosives and poisons and intrusion of exotic species are the major possible factors noticed in the present study which cause the depletion of fish population in the study area. Several authors have observed that a sharp decline in the fish population has been recorded in Indian rivers due to the indiscriminate fishing of brood stock and juveniles, fast degradation of aquatic ecosystems and the construction of dams, barrages, weirs, etc. Indiscriminate fishing of brood fish and juveniles and the use of explosives, poisons and electrocution are some of the major possible factors that cause the depletion of fish in Indian waters.
The indigenous fishermen have more preference towards fish species of large
size and with medicinal properties. The use of different types of plant
products by indigenous fishermen for fishing was observed, which kill all the
fish fauna including juveniles.
Fish collected from various waterbodies of the southern Western Ghats.
The pristine riverine systems along the Western Ghats have been altered by
anthropogenic activities such as dam constructions and road building, which
have affected the ecology and habitat of these fish fauna. The tourist
resorts starting down at Athirappilly on the bank of the Chalakudy River are
altering the habitat in many ways. Sholayar Hydro Electric Project and
Peringalkuthu Hydro Electric Project are the hydroelectric projects on the
Chalakudy River. There are about seven dams built on the river. Peringalkuthu
Dam in this river prevents the local migration of
The fish population is declining rapidly among the streams and rivers of the southern Western Ghats. Hence the following immediate conservation measures will help to conserve these precious species. Awareness among the tribes is very important for the conservation of fish species. Awareness can be increased about the impact of using chemicals for mass poisoning, dynamiting for catching fish, fishing during breeding seasons and the use of poisonous plant products for mass poisoning. Students, social workers, fishermen and local people should be educated about the importance of conservation of fish fauna in their area so that they can create awareness among the people in the area. More exclusive projects should be started with the co-operation of local people and students to protect the fish population. Action can be taken to change the fishing profession of those who only depend on fishing for their livelihood, which will help to reduce the fishing pressure.
In order to conserve fish genetic resources and provide adequate living
space, shelter and habitat for valuable threatened fish fauna, certain areas
can be declared fish sanctuaries, like national parks and wildlife
sanctuaries. Menon et al. (2000) suggested that suitable segments of the
rivers with fish species should be identified for the establishment of fish
sanctuaries and that such sanctuaries must be heavily stocked every year with
fish fingerlings. There are two fish sanctuaries protecting the
Captive breeding is a technique widely used throughout the world for a
variety of endangered animals including fish (Maitland and Evans, 1986;
Keshavanath et al., 2006). It could be an important last resort measure for
endangered and endemic species, which may otherwise become extinct in the
wild (Reid, 1990). Fishery departments should take steps for the breeding and
caring of the endangered
The monitoring and documentation of fish stocks are becoming significantly important to carry out regular reviews of the distribution and status of all fish species, and this will be possible by maintaining records (Koljonen and Nyberg, 1991). The documentation of genetic resources for aquaculture is also a part of the coverage of the FishBase database (Froese and Pauly, 2013). The comprehensive listing of fish species' distribution as well as the continuous monitoring of fish species are a critical need for the protection of fish fauna.
The data have been submitted in the Pangaea data bank and
they
can be accessed by the following link
(
In the present study, from the fish fauna that were
collected from various river systems of the southern Western Ghats, like
Bhavani, Moyar, Chalakudy, Periyar, Cauvery and Kabini, it is noted that the
order Cypriniformes was the most dominant order, with 3 families, 18 genera
and 49 species (76.6 %), compared to other orders. Interestingly, sites
like Thunakadavu stream, Gulithuraipatti, Athirappilly, Naduthotam,
Nadathittu, Mullaithodu, Thonanthikla, Noolpuzha and Sinnaru revealed high
species diversity. The results indicated that the species from the southern
Western Ghats have an ambiguity in their taxonomy among the fishing
communities. The data analyses suggested that species like
Both the authors have equally taken part in all aspects of the work and manuscript preparation.
The authors declare that they have no conflict of interest.
The authors gratefully acknowledge the University Grants Commission for providing the funding for this research, Tamil Nadu, Kerala and Karnataka forest departments for the permission and logistic support and the Department of Environmental Sciences, Biodiversity and Molecular Laboratory, Bharathiar University, Coimbatore, Tamil Nadu, India, for providing laboratory facilities for the research. Edited by: Falk Huettmann Reviewed by: two anonymous referees