Abstract: The present investigation undertakes to study endemic and threatened fish species and its assemblage structure from rivers of Kolhapur district for the period July-2012 to December-2014. The study area is situated in the extreme Southern part of Maharashtra state. It contributes much more part of Western Ghats. A total of 23 species belonging to 7 families and 19 genera were reported. In which 9 species are threatened and 20 species are endemic to Western Ghats, we found that 6 species are threatened as well as endemic. Puntius sahyadriensis, Nemacheilus anguilla, Pterocryptis wynaadensis and Glyptothorax trewavasae are first time reported from Kolhapur district. High Shannon diversity index shows considerable variation and ranges from 1.34-2.43. Margalef’s diversity index and Evenness index for each sampling site were also recorded. The similarity in cluster analysis from nearby sampling site along the river has similar faunal assemblage. The problems related to various threats for aquatic biodiversity and conservation management strategies have been discussed.
INTRODUCTION
The significance of endemism was studied by some workers in plants as well as in animals. Endemic species are of both locally and globally important, because they increase the amount of genetic diversity and offer insight into biogeographical questions, like where certain species originated and how distribution patterns have changed over time (Skarbek, 2008; Muderhwa and Matabaro, 2010). They are related to biogeography that denotes the unique occurrence of a living species in the ecological state of a well defined geographic location that may be a small local area with unique niche characteristics (Venkataraman et al., 2013). The Western Ghats is one of the hotspots of biodiversity in the world and endowed with rare, endemic and threatened species of flora and fauna (Hanson et al., 2009). The freshwater fish fauna are one of the most important threatened and endemic taxonomic group of the Western Ghats that contribute critical ecological role in aquatic ecosystem (Holmlund and Hammer, 1999). Recently 320 freshwater fish species belonging to 11 orders, 35 families and 112 genera were reported from the Western Ghats and out of which 212 are endemic to the Western Ghats (Dahanukar and Raghavan, 2013). Due to the high number of endemic species there is need to study extensively, with the help of biotic and abiotic parameters; that may affects the diversity, community structure and species assemblages in lotic environment (Minns, 1989).
Variation in abiotic factors such as flow, depth, substrate and water quality along with various physicochemical parameters may have significant impact on both, assemblage structure and resource availability (Johnson et al., 2012) of freshwater fishes. In India, some studies have been undertaken for documentation of fish diversity and assemblage structure (Johnson, 1999; Bhat, 2003, 2004; Sreekantha et al., 2007; Shahnawaz et al., 2010). Most of these studies are reported from Central and Southern Western Ghats. From Northern Western Ghats, only one assemblage structure study is reported (Arunachalam, 2000).
From the conservation point of view, various threats and conservation strategies were reported by earlier researchers from Western Ghats. Important threats recorded by earlier researchers includes introduction of alien fish species, industrial and urban pollution, habitat loss, big dam constructions and unmanaged aquarium trade (Paingankar and Dahanukar, 2013; Katwate et al., 2013). In addition, some study also revealed that the global warming is an important major threat of endemic species from biodiversity hotspot (Malcolm et al., 2006). Therefore, there is a need to initiate conservation measures to protect the endemic and threatened species. Minimize human encroachment in aquatic habitat and sustainable utilization of aquatic resources.
The review of literature from study site shows that, Kalawar and Kelkar (1956) studied the fishes of Kolhapur and reported 72 species. After this attempt, Pawar (1988) studied the ichthyofauna from Panchganga river separately and he reported 48 species and concluded the decline in number of fish fauna of Kolhapur. Mohite and Samant (2013) studied the fish and fisheries in Warana river basin, they recorded 42 species. Thus, the main objective of this study is to study assemblage structure, assess abundance, diversity, distribution, richness of endemic and threatened fishes from Northern Western Ghats of Kolhapur district.
MATERIAL AND METHODS
The present study encompassed 14 sampling sites (Fig. 1) in main river basin of Kolhapur district. Namely Kodoli and Khochi on Wararna river, Bajar Bhogaon on Kasari river, Kale, Prayag chikhali and Kurundwad (Near Krishna river) on Panchganga river, Rashiwade on Bhogavati river, Kagal karnur on Doodhganga river, Bastwade on Vedganga river, Chandewadi on Hiranyakeshi river, Adkur on Ghatprabha river, Kowad on Tamraparni river, Gavashi on Dhamani river and Saitwade on Kumbhi river. Location of each sampling site was documented by using global positioning system (Table 1). The collection of fish sample was done with the help of local fishermen using gill nets, cast nets of different mesh sizes and type of river basins. Fish sampling protocol followed the method of Johnson and Arunachalam (2009). During the collection, fishes were examined, counted and released back into the basin, while unidentified species were brought to the laboratory, properly preserved in 10% buffered formalin and transported to lab for confirmation.
| Table 1: | Details of the sampling sites |
| Fig. 1: | Study map showing different sampling sites on river |
Identification of collected fish was done on the basis of morphological features with the help of standard keys (Jayaram, 1999, 2009, 2010). After catching, photographs of fishes were taken immediately as well as in the laboratory using DSLR Camera (EOS 60D, Canon inc, Japan). The confirmatory identification of species was done at Zoological Survey of India, Western Regional Centre, Pune. All identified specimens are deposited in Department of Zoology, Shivaji University, Kolhapur.
Statistical analysis: For statistical analysis different diversity indices were calculated, namely Shannon diversity index, Margalef’s index, Buzas and Gibson’s evenness and Simpson’s dominance index.
Shannon index (Shannon and Weaver, 1949): A diversity index, taking into account the number of individuals as well as number of taxa, varies from 0 for communities with only a single taxon to high values for communities with many taxa, each with few individuals:
where, ni is number of individuals of ‘i’ taxon and n is total number of individuals.
Margalef’s index (Margalef, 1958):
where, S is number of species and N total number of individuals.
Buzas and Gibson’s evenness index (Buzas and Gibson, 1969):
where, H refers to Shannon weaver index and S is species number.
Simpson dominance index (Simpson, 1949): Ranges from 0 (all taxa are equally present) to 1 (one taxon dominates the community completely):
where, ni is number of individuals of ‘i’ taxon.
Clustering analysis: Dendrogram were constructed to assess the resemblance of fish assemblage structure among the sampling sites by using the Bray-Curtis similarity index using non-transformed species abundance data (Anderson, 2001) using PAST Version 2.17 programme (Hammer et al., 2001).
RESULTS
A total of 23 species belonging to 7 families and 19 genera were recorded (Table 2). In which 6 species are endangered (26%), 3 species are vulnerable (13%), 2 species are near threatened (9%), 11 species are least concern (48%) and 1 species has data deficient (4%) as per IUCN red list of threatened species (Fig. 2).
| Table 2: | Check list of fish species collected from different rivers of Kolhapur district with IUCN redlist category |
| *E: Endemic to Western Ghats, NE: Not endemic to Western Ghats, I: Introduced. **LC: Least concern, NT: Near threatened, VU: Vulnerable, EN: Endangered, DD: Data deficient | |
Out of 23 fish species, 20 species are endemic to Western Ghats (Dahanukar and Raghavan, 2013). In the present study, cyprinids were the most dominant group represented by 9 species belonging to 8 genera followed by Bagridae (4 species from 2 genera), Nemacheilidae (4 species from 4genera), Schilbidae ( 2 species from 2 genera), Sisoridae (2 species from 2 genera), Cobitidae (1 species ) and Siluridae (1 species ) (Fig. 3). From study sites, Puntius sahyadriensis, Nemacheilus anguilla, Pterocryptis wynaadensis and Glyptothorax trewavasae are first time recorded from rivers of Kolhapur district (Table 3). Pterocryptis wynaadensis from the Hiranyakeshi river at Chandewadi, Glyptothorax trewavasae were recorded from Panchganga river at Prayag Chikhali sampling site.
| Fig. 2: | Percentage composition of conservation status (IUCN) of fish fauna |
| Fig. 3: | Percentage composition of families |
Three species namely Nemacheilus anguilla, Glyptothorax trewavasae and Puntius sahyadriensis were reported by Jadhav et al. (2011) from Koyna river at Wai. As per reviews and literature available, the Pterocryptis wynaadensis are presently reported from few localities namely Kabini, Kuttiyadi, Chandragiri, Tungabhadra, Bedti, Bhavani, Moyar, Tambraparni and Neerar River Systems (Raghavan et al., 2007). The highest number of individuals is observed from family Bagridae. A total of 161 individuals of Mystus malabaricus 25.63% were recorded followed by Mystus seengtee 15.60% (98) and Hypselobarbus curmuca 10.19% (64). The remaining species wise percent composition is also calculated (Fig. 4).
High Shannon diversity index showed considerable variation and ranged from 1.34-2.43 indicates a strong relationship with overall species richness. The maximum fish diversity index was observed in middle stretch as compared to lower and upper stretch. The highest fish diversity was recorded from Panchganga river on Prayag Chikhali sampling site i.e. 26.43%. The lowest diversity was recorded from Ghatprabha and Tamraparni river on Adkur and Kowad sampling site (3.50 and 3.18%), respectively. Margalef’s diversity index, Simpson dominance index and Evenness index for each sampling site was also recorded (Table 4).
| Table 3: | List of fish species recorded at each sampling site |
| Fig. 4: | Percentage composition of species |
The similarities in species composition among the sites were analyzed by using the Bray-Curtis similarity index. A positive relationship were observed from nearby sampling site along the river have similar faunal assemblage. The similarity in species composition across all sampling sites is shown in dendrogram (Fig. 5).
Notes on new records
Puntius sahyadriensis (Fig. 6a): Body short, compressed, head is more or less blunt, eyes large situated more towards the anterior half of the head. The barbels are absent. Body with seven vertical black bands. Pelvic fin shows black and white colouration.
| Table 4: | Summary of variation in species abundance, richness index, Shannon index, evenness index and dominance |
| Fig. 5: | Dendrogram resulting from Bray-Curtis similarities of species abundance data of study sites |
| Fig. 6(a-d): | (a) Puntius sahyadriensis, (b) Glyptothorax trewavasae, (c) Nemacheilus anguilla and (d) Pterocryptis wynaadensis |
Glyptothorax trewavasae (Fig. 6b): Head small, depressed and covered with thick skin. Mouth conical but not pointed. Lips thick, fleshy, papillated. Four pairs of barbels; one pair of maxillary, one pair of nasal and two pairs of mandibular. Adhesive apparatus well developed extending forward to a point between union of gill membranes with isthmus.
Nemacheilus anguilla (Fig. 6c): Body loach like, dorsal fin with eight branched rays, body with a row of black blotches running along midlateral line and extending up to the caudal fin. Small spots also present on dorsal and caudal fins.
Pterocryptis wynaadensis (Fig. 6d): Body laterally compressed, head somewhat flattened and broader than body. Eyes small situated just above the angle of the mouth. Snout with rounded anterior profile. Two pairs of mandibular barbels. Caudal fin rounded.
DISCUSSION
The present study revealed that the rivers of Kolhapur district have a diverse ichthyofauna of high conservation importance. In present study, 23 species were observed when we compare this data to previous available literature, the number of species are going to decline. As expected, the cyprinids dominate the assemblage structure as they occupy all possible habitats and due to their high adaptive property. We pointed that, number of endemic species like Tor khudree, Botia striata, Gagata itchkeea, Schismatorhynchos nukta and Pachypterus khavalchor become very rare. From Kolhapur district including Warana river, Kalwar and Kelkar (1956) got 71 species in which most of the species are abundant, after this attempt Mohite and Samant (2013) reported 42 species in which 19.04% species are become very rare when they compare the data to earlier. In our finding, Tor khudree, Botia striata, Gagata itchkeea, Schismatorhynchos nukta, Pachypterus khavalchor and Rita gogra become rare. Similar results were obtained from Panchganga river but the species namely Gagata itchkeea, Rita kuturnee, Rita gogra, Proeutropiichthys taakree, Garra bicornuta and Nemachilichthys ruppelli are very rare. Due to lack of fish diversity data from Dudhaganga, Vedganga, Hiranyakeshi, Ghatprabha and Tamraparni rivers, it is not possible to assess the rate of decline in endemic and threatened fish species from Kolhapur district. Another important finding is first report of Puntius sahyadriensis, Nemacheilus anguilla, Pterocryptis wynaadensis and Glyptothorax trewavasae from study sites.
The earlier researchers concluded that, the species richness, diversity and its abundance is increased from upstream to downstream (Welcomme, 1985; Bayley and Li, 1994; Lorencio, 2000). But the present results revealed that the middle stretch sampling site (Prayag chikhali) of Panchganga river has higher species richness, diversity and its abundance. Numbers of threats were recorded from tributaries of Panchganga that affects the assemblage structure of Kasari, Kumbhi, Dhamani and Bhogawati rivers. The main threats recorded includes drying of upper stretch during summer month and at the same time use of dynamites for fishing purpose, fragmentation due to construction of dams and weirs, sand mining, agriculture expansions and over fishing. All these factors collectively contributes the destruction of natural habitat of aquatic fauna. Due to all such factors, the species richness was high in middle stretch of Panchganga river at Prayag Chikhali sampling site as compared to lower and upper stretches sampling sites. Whereas, at remaining sampling sites namely Kagal karnur on Doodhganga river, Bastwade on Vedganga river, Chandewadi on Hiranyakeshi river, Adkur on Ghatprabha river and Kowad on Tamraparni river same threats were recorded that affects the assemblage structure.
The present attempt provides data concerning the assemblage structure and diversity of endemic and threatened fish species from Northern Western Ghats of Kolhapur district. From this small attempt it is concluded that, the number of threats to fish fauna from rivers of Kolhapur district is very high. There is an urgent need to take a concrete decision towards the conservation of ichthyofauna. If the present trend continues, the adverse conditions might lead to the loss of the ichthyofauna from Northern Western Ghats of Kolhapur district.
ACKNOWLEDGMENTS
The authors are thankful to DBT-IPLS programme (Grant No. BT/PR 4572/INF/22/147/2012), New Delhi for financial support and encouragement. We are thankful to Department of Zoology for providing laboratory facilities. We are thankful to Dr. Pankaj Bhatnagar, Officer-in-charge and Dr. Shrikant Jadhav, Zoological Survey of India, Western Regional Center, Pune for identification of fish species.