Diversity,
distribution and assemblage structure of fishes in streams of southern Western
Ghats, India
J.A. Johnson 1 & M. Arunachalam2
1 Wildlife Institute of India, P.BoxNo. 18, Chandrabani, Dehradun,Uttarakhand 248001, India
2 Sri Paramakalyani Centre for
Environmental Sciences, Manonmaniam Sundaranar University, Alwarkurichi,
Tamil Nadu 627412, India
Email: 1 jajohny@rediffmail.com
Date of publication
(online): 26 October 2009
Date of publication (print): 26
October 2009
ISSN 0974-7907 (online) |
0974-7893 (print)
Editor: Neelesh Dahanukar
Manuscript details:
Ms # o2146
Received 13 February 2009
Final received 16 October 2009
Finally accepted 17 October 2009
Citation: Johnson, J.A.
& M. Arunachalam (2009). Diversity, distribution
and assemblage structure of fishes in streams of southern Western Ghats, India.Journal of Threatened Taxa 1(10): 507-513.
Copyright: © J.A. Johnson
& M. Arunachalam 2009. Creative Commons
Attribution 3.0 Unported License. JoTTallows unrestricted use of this article in any medium for non-profit purposes,
reproduction and distribution by providing adequate credit to the authors and
the source of publication.
Author Details: Dr. J.A. Johnson, a freshwater fish ecologist, completed his PhD
from Sri Paramakalyani Centre for Environmental
Sciences, Manonmaniam SundaranarUniversity, AlwarkurichiTamil Nadu. He has a vast knowledge on taxonomy and ecology of freshwater
fishes of India. Presently he is working as a Scientist in the Wildlife
Institute of India, Dehradun.
Dr. M.
Arunachalamis a Professor and Head at Sri Paramakalyani Centre
for Environmental Sciences, Manonmaniam Sundaranar University, Alwarkurichi Tamil Nadu. He is a leading
ichthyologist working on taxonomy and ecology of hill stream fishes of Western
Ghats and conservation and management of wetlands.
Author Contribution: The study: JAJ
works on taxonomy, ecology and conservation of freshwater fishes of India. MA -
Supervision of taxonomy and ecology of freshwatterfishes of Western Ghats. Current paper: JAJ - involved in field sampling, data
analysis and prepared the manuscript. MA - assisted in field sampling and
technical guidance in data analysis.
Acknowledgements: JAJ is grateful
to the Department of Science and Technology, New Delhi for the financial
support under Fast Track Young Scientist scheme. Critical comments from an
anonymous reviewer in improving the quality of the manuscript are sincerely
appreciated.
Abstract: Diversity,
distribution and assemblage structure of fishes were studied in 10 selected
streams of southern Western Ghats. The
sampling was performed between April 2001 and March 2002. Sixty species of primary freshwater fishes
belonging to four orders, 13 families and 27 genera were recorded from the
study area. Cyprinids were the most
dominant assemblage members in all study streams. Maximum number of species, number of
individuals and cyprinids were recorded from Thalayanaistream. More specialized forms Homaloptera santhamparaiensis, Glyptothorax madraspatanum, Noemacheilus guentheri, N. keralensis,
N. semiarmatus and N. triangulariswere recorded in Panniyar stream. High diversity was observed in Achankoil stream. Evenness
index of similarity was uniform in all study streams. Similarity cluster
analysis showed streams from nearby basins had similar faunal assemblages. Principal Component Analysis was performed to
study the similarity of fish assemblages between the study streams. The analysis described clear pattern of
segregation between Thalayanai and Karaiyar (east flowing) and Kallarand Achankoil (west flowing) streams. Thirty-nine
Western Ghats endemic fishes were recorded from the study area. Current distribution
and threats to endemic fishes are discussed.
Keywords: Assemblage
structure, endemic fishes, fish diversity, species richness, Western
Ghats.
For Figures & Tables –
click here
Introduction
Freshwater habitats in
rivers, streams, springs and headwaters are heterogeneous due to variations in
altitude, flow rates, dissolved oxygen, physical substrate and the riparian
zones that provide food, shade and cover (Armantrout1990). As a result, freshwater habitats harbour diverse fauna, with fish serving as prime
indicators of ecosystem status (Karr et al. 1986). Riverine fauna show
a high degree of endemism, with most endemic fish species living in headwater
streams and/or short stretches of river (Groombridge1992; Kottelat & Whitten 1997). Thus riverinefreshwater habitats are among the least studied, and likely many species still
await discovery (Kottelat & Whitten 1997).
The Western Ghats biogeographic region of India is home to a highly diverse
fish fauna, consisting of 288 known species belonging to 12 orders, 41 families
and 109 genera (Dahanukar et al. 2004), of which 116
(53%) species are endemic to this region (Daniels 2001). Until recently few details on abundance and
assemblage organization were available for streams and rivers (Silas 1951;
1953; Rajan 1963; Johnsingh& Vickram 1987; Devi 1992; Devi & Menon 1994; Devi et al. 1997; Easa& Shaji 1997; Johnson & Soranam1999; Arunachalam & Johnson 2002; Arunachalam et al. 2002), however, recent studies have
examined diversity distribution and assemblage organization. Arunachalam (2000)
studied association of microhabitat variables to species diversity and habitat
usage, and diversity, endemism and distribution patterns of fishes have been
studied in the central (Bhat, 2003; 2004; Dahanukar et al. 2004) and Kerala regions (Raghavan et al. 2008). While reports on the fish assemblage and distribution patterns seem to
cover the Western Ghats fairly well, gaps remain with regard to assemblage
structure of the southern region. Thus
the main objective of this study is to describe fish assemblage structure in
streams of the southern Western Ghats, assess species diversity and similarity
of faunal assemblage between streams and evaluate endemism and current
conservation status of Western Ghats fish populations.
Materials and Methods
Study Area: The southern
Western Ghats lie between 80-120N & 760-780E. The region covers about 500km of mountain
valleys shared by Tamil Nadu and Kerala. The important ecoregionsof this area are Agasthyamalai, Anamalai,
Cardamom hills and Nilgiris. This hill chain is interrupted in the north
by the 30km wide Palghat gap at around 110N, and
south of this gap lies the Anamalairange of hills with its highest peak Anaimudi at
2695m. This area receives precipitation
from both southwest (June to September) and northeast (October to November)
monsoons and the average annual precipitation exceeds 2,800mm. Many torrential and perennial hill streams of
this region are the main source of major west and east flowing rivers. The western portion is drained by the Vamanapuram, Pamba, Periyar, Bharathapuzha and Chaliyar. In
addition to major rivers, number of quick flowing streams originate and quickly
discharge into Arabian Sea. The eastern
portion is drained by the Tamiraparani, Vaigai, Moyar, Bhavani and Cauvery rivers. In the present study ten streams covering major river basins in Tamil
Nadu and Kerala states were selected (Fig. 1) and the sampling was carried out
between April 2001 and March 2002. The
study streams and their general features are given in Table 1.
Data collection: Fish
sampling was performed in 100m reach of all study streams. In each stream the
sampling was made in different habitats such as pools, riffles, runs and
cascades using monofilament gill nets of different mesh sizes (10 to 34 mm),
drag, scoop and cast nets. Fish sampling followed the method of Arunachalam (2000). After collection fishes were examined, counted and released. A few
specimens (5-10) of unidentified species were preserved in buffered formalin
(10%) and transported to the laboratory for analysis. Species identification
and confirmation were carried out using standard fish taxonomy textbooks (Talwar & Jhingran 1991; Jayaram 1999). Data
on current conservation status was obtained from reports of the Conservation
Assessment and Management Plan workshop (Molur &
Walker 1998) on freshwater fishes of India.
Analysis: Information
about structure of assemblages was extracted by adopting different univariate indices, namely Margalef’sspecies richness index, Shannon diversity index and Shannon evenness
index. The calculation of these indices
was followed by the methods of Magurran (1988) and Padhye et al. (2006). Margalef’sspecies richness is calculated using the equation R = (S-1)/lnN, where S is the number of species, N is the total number of individuals. The Shannon index of diversity is obtained by
the following equation H’ = ∑ pi. In pi, where pi = ni/N; ni is the number of
individuals of ‘i’th species and N = ∑ni.
Evenness index is calculated by E = H’/lnS, where S
is the number of species. The indices
were used to compare the species richness, diversity and equitability across
the study streams. The quantitative data
of species along with the number of individuals belonging to each species were
used to calculate percent similarity index using Bray-Curtis similarity index
based on Padhye et al. (2006). Dendrograms were
constructed to understand the similarity between the sampling sites. This was done using Bray-Curtis similarity
index using non-transformed species abundance data (Anderson 2001). Further, Principal Component Analysis (PCA)
was performed to study the similarity of fish assemblage between the study
streams and understand which species contributed to the difference in fish
assemblage between east and west flowing streams.
Results
Fish assemblage structure, species diversity and similarity:
During the study a total of
60 species of primary freshwater fishes belonging to four orders, 13 families
and 27 genera were recorded from the study streams (Table 2). Number of species, total abundance, cyprinid
abundance and their percentage, richness index, Shannon diversity and evenness
index for study streams are given in Table 3. Maximum numbers of species and individuals were recorded in Thalayanai stream, while low number of species and
individuals were recorded in Hanumannadhi stream. In
the assemblage structure, cyprinids constituted the dominant group (72.6 to
92.3%) and the cyprinids Danio aequipinnatus, Garra mullya and Rasbora daniconius were represented in all the study
streams. The maximum number of cyprinid
individuals was recorded from Thalayanai stream,
which represented a number of big sized barbs such as Hypselobarbus curmuca, H. kolus, H. dubius, H. dobsoni, Tor khudree and Barbodes sarana. Low cyprinid populations was observed in Bhavalipuzha,
followed by Panniyar stream and these streams harboured some specilized forms
like Homaloptera santhamparaiensis, Glyptothorax madraspatanum,Noemacheilus guentheri, N. keralensis, N. semiarmatus andN. triangularis. Shannon diversity index showed high value
in Achankoil, Kallar and Bhavalipuzha streams. The evenness index of species distribution was uniformly similar in all
study streams except Thalayanai stream, where the
equitability of species was low.
Cluster analysis of species
composition showed that the streams from near by basins had similar faunal
assemblage when the dendrogram was drawn based on the
Bray-Curtis similarity index (Fig. 2). Among the east flowing streams, Karaiyar and Thalayanai had more
similarity in fish species assemblage. Similarly, in west flowing
streams, Bhavalipuzha and Thalipuzhahad similar fish assemblage. Principal Component Analysis showed a clear
pattern of similarity between the study streams with respect to the fish
assemblage (Fig. 3). PCA extracted three
significant factors with factor loading above one. These three factors together explained about
70% of total variation in the data. West
flowing rivers (S1, S6, S7 and S8) were separated from the east flowing rivers
mainly on the F2 axis (separated by a transparent plane in Fig. 3). Out of the total 60 fish species, 29 had
positive factor loading on F2 axis and were either restricted or had high
abundance in the west flowing streams while 31 had negative factor loading on
F2 axis and were either restricted or had low abundance to east flowing
rivers. Out of these, fishes like Puntius conchonius, Danio(Brachydanio) rerio, Garra gotyla stenorhynchus, Mystus armatus and Pseudambassis ranga, which were restricted to the east
flowing streams and Puntius denisonii and Etroplusmaculates, which were restricted while west flowing streams showed similar
pattern to the one documented by Easa & Shaji (1997). Other
fish species which were restricted to east flowing streams were Barbodes carnaticus,Horalabiosa joshuai,Hypselobarbus curmuca,H. dobsoni, H. dubius,H. kolus, H. micropogon,Puntius kannikattiensis,P. parrah, Rasbora caverii and Salmostoma clupeoides and those restricted to the west
flowing streams were Hypselobarbus kurali, Puntius fasciatus, Puntius arenatus, Homaloptera santhamparaiensis, Noemacheilus keralensis and Batasio travancoria.
Endemism and current conservation status:
Out of 60 species, 39
species are endemic to Western Ghats of Peninsular India (Table 4). Among the endemic species nine are strictly
endemic to west flowing systems of southern Western Ghats (Barilius bakeri, Batasio travancoria, Gara hughi, Horalabiosa arunachalami, Homaloptera santhamparaiensis, Hypselobarbus kurali, Puntius denisonii, Noemacheilus guentheri and N. keralensis)
and five are endemic to east flowing system of southern Western Ghats (Garra gotyla stenorhynchus, Horalabiosa joshuai, Hypselobarbus dubius, Puntius tambraparniei and Puntius kannikattiensis). Out of 39 endemic species, 25 (64%) are in threatened categories (Table
4), of which three species, Puntius tambraparniei, Puntius narayani and Silurus wynaadensis are Critically Endangered; 14 species
(Garra gotyla stenorhynchus, Bhavania australis, Garra hughi, Puntius denisonii, P. dorsalis, P. fasciatus, P. parrah, Hypselobarbus curmuca, H. kolus, H. kurali, H. dubius, H. micropogon, Noemacheilus keralensis and Botia striata) are
Endangered; eight species (Barbodes carnaticus, Barilius bakeri, Batasio travancoria, Clarias dussumieri, Glyptothorax madraspatanum, Proeutropiichthys taakree taakree, Tor khudree and Noemacheilus semiarmatus) are in Vulnerable categories (Molur & Walker 1998).
Discussion
The Western Ghats streams exhibit high
variability in fish assemblages and the assemblage composition is determined by
specific ecological conditions. Notable
highest diversity of species richness and endemic forms are encountered in Thalayanai, Kallar and Achankoil streams of southern Western Ghats. Ali & Ripley (1983) hypothesized that the
southernmost division of the Western Ghats (south of PalghatGap 80 - 90N) seems to be a natural pass which has played a significant role in
isolating a variety of organisms on either side for a long period of time. This proposition is supported by diversity
patterns in birds (Ali & Ripley 1983), amphibians (Daniels 1992; Bhatta 1997) and flora (Nayar1996). Moreover, the high hill ranges
(Malabar, Travancore hills of Kerala and Nilgiris, Anamalai, Palani and Tirunelveli hills of Tamil Nadu) are largely restricted to
south of 110N. Thus it is evident that
environmental conditions such as widespread rainfall (both south-west and
north-east monsoons) and cooler climate have played important roles in
diversity patterns and endemism in the southern Western Ghats (Daniels 1992; Dahanukar et al. 2004). The diversity of fish species observed in the present study is in line
with findings for other flora and fauna.
The species richness of river fauna may
be dependent on the accessibility of streams (Horwitz1978). The high species richness streams
of Thalayanai and Achankoilare located in well protected areas and less accessible to people. In addition to the stream accessibility,
diversity and distribution patterns of freshwater fishes are associated with
different sets of environmental gradients that have been well studied in streams
of the Western Ghats (Johnson 1999; Arunachalam 2000;Bhat 2003, 2004). In the present study streams from west flowing systems encountered more
endemic forms. These endemic fishes are
usually well specialized, and their movements along the river may be very
limited. For example, the species Puntius denisonii is endemic to Achankoil river, found only in rapids of the upstream
region. Moreover, the west flowing
streams originate from high hills and have short stretches with series of
rapids and pools, and the fauna of rapids are known to have a very high rate of
endemism (Easa & Shaji1997; Kottelat & Whitten 1997).
In the present findings, cyprinids
dominate the assemblage structure as they occupy all possible habitats in
Western Ghats streams due to their high adaptive variability. Four of the recorded species, Danio aequipinnatus, Garra mullya, Puntius filamentosus and P. conchonius have widespread distribution in India (Talwar& Jhingran 1991; Jayaram1999) and they are common and abundant species in Western Ghats streams. Such extensive distribution and their common
high abundance suggest that most of these species are capable of tolerating a
wide range of environmental conditions. Ajithkumar (1997) pointed out that the distribution of hill
stream loaches, Bhavania australis, Noemacheilus denisoni, N. guentheri, N. semiarmatus and N. triangularis are
restricted to Mysore, Nilgiris and in the central
part of Western Ghats. In this study
these species are recorded from various streams in the southern Western Ghats
(Table 2), showing that they have well established distribution. Moreover, the endangered big sized barbs Hypselobarbus curmuca (known
from Krishna, Godavari and Cauvery basin); H. dobsoni (known only from Krishna river basin); H. dubius (small population in Cauvery at Nilgiris); H. kolus (small numbers in Godavari, Krishna and Cauvery)
have very restricted distribution and small fragment of population exist in the
Western Ghats rivers (Talwar & Jhingran 1991; Menon 1992; Molur & Walker 1998; Jayaram1999). Viable populations of these
endangered species are found in the Thalayanaistream, new from the present study. These restricted and patchy distributions of species have led to small
and vulnerable populations.
The present work shows remarkable
species diversity and endemism in the southern part of the Western Ghats, and
the recent description of three new species (Horalabiosa arunachalami, Homaloptera santhamparaiensis and Puntius kannikattiensis) from the study area indicate
that our understanding of the diversity of fish in this area is still far from
being complete. Moreover, the study also
revealed that many species in the study area are being threatened by various
human activities. The major activities
are habitat modification, sand mining, removal of
riparian vegetation, agriculture activities and destructive fishing. Habitat modifications are very common in
southern Western Ghats streams where the channels are locally modified for
various purposes like extraction of water for drinking, agriculture etc. As a result there is low surface flow water
available in the downstream area and which creates threats tomany localized species. In addition,
increased sedimentation due to removal of riparian vegetation and entry of
agricultural runoff causes severe threats to Western Ghats fish diversity. These lead to silt deposition along the
stream bed, converting the heterogeneous stony substrate into homogenous sandy
substrates and ultimately results in loss of spawning habitat for many fish
species. Another major threat to
freshwater fish is sand mining along the stream channel which leads to
formation of more deeper pools and loss of run and riffle habitats. Moreover, along with sand the microbial and
other invertebrate communities in the stream bottom also get lost, as a result
the resource availability for stream fishes would affect. In addition to that, destructive fishing
methods like liming, mixing latex of euphorbia, poisoning in stream pool also
bring drastic effects on fish diversity. Special attention is to be given for conservation of these threatened
species, especially the highly threatened large barbs of the Western Ghats,
through captive breeding and ranching. Furthermore, habitat requirements of many of the threatened and endemic
species are poorly understood and more detailed studies are warranted.
References
Ajithkumar, C.R. (1997). Biodiversity of the Western Ghats in India, with special reference
to conservation of its fish fauna. Species (IUCN) 29: 13–14.
Ali, S. & S.D. Ripley (1983). Handbook of the Birds of India and Pakistan (compact).Oxford University Press, New Delhi, 737pp.
Anderson, M.J. (2001).Permutation tests for univariate or multivariate
analysis of variance and regression. Canadian Journal of Fisheries and Aquatic Sciences58: 626–639.
Armantrout,
N.B. (1990). Conservation in developing countries In: Daniel, J.C. & J.S. Serrao(eds). Problems and prospects,
Proceedings of the centenary seminar on the Bombay National History Society,
656pp.
Arunachalam,
M. (2000).Assemblage structure of stream fishes in the Western Ghats. Hydrobiology430: 1–31.
Arunachalam, M. & J.A.
Johnson (2002).A new species of Puntius (Hamilton)
from Tamiraparani river. Journal
of Bombay National History Society 99(3): 474–480.
Arunachalam,
M., J.A. Johnson & K. Rema Devi (2002). Homaloptera santhampariensis,
a new species of Balitorid fish (Teleostei:Balitoridae) from a Western Ghats stream of Kerala,
India. Acta Zoologica Taiwanica 13(1): 31-37.
Bhat, A. (2003). Diversity and composition of freshwater fishes in the river systems
of Central Western Ghats, India. Environmental Biology of Fishes68: 25–38.
Bhat, A. (2004). Patterns and distribution of freshwater fishes in rivers of Central
Western Ghats, India and their association with environmental gradients. Hydrobiologia 529: 83-97.
Bhatta, G. (1997). Caecilian
diversity of the Western Ghats: In search of the rare animals. Special section: Biodiversity of Western
Ghats. Current Science 73(2):
183–187.
Dahanukar,
N., R. Raut & A. Bhat(2004). Distribution, endemism and threat status of freshwater fishes
in the Western Ghats of India. Journal of Biogeography31(1): 123-136.
Daniels, R.J.R. (1992). Geographical
distribution patterns of amphibians in the Western Ghats, India. Journal of Biogeography 19: 521–529.
Daniels, R.J.R. (2001). Endemic fishes
of the Western Ghats and the Satpura hypothesis. Current
Science 81: 240–244.
Devi
K.R., T.J. Indra, M.B. Raghunathan,
M.M. Bai & M.S. Ravichandran(1997). Ichthyofauna of the Tamiraparani river system, Tamil
Nadu. Zoos’ Print Journal 12(7): 1-2.
Devi
K.R. & A.G.K. Menon (1994). Horalabiosa palaniensis,A new cyprinid fish from PalaniHills, Western Ghats, South India. Journal of Bombay Natural History &
Society 91: 110-111.
Devi K.R. (1992). Fishes of Kalakad Wildlife Sanctuary, Tirunelveli District, Tamil Nadu, India. Records
of Indian Museum 92(1-4): 193-209.
Easa,
P.S. & C.P. Shaji (1997). Freshwater fish diversity in Kerala part of NilgiriBiosphere Reserve. Current Science 73(2): 180 –182.
Groombridge, B. (ed.)
(1992). Global biodiversity status of earth’s living resources.Chapman and Hall, London, 585pp.
Horwitz, R.J. (1978). Temporal variability patterns and the distributional patterns of
stream fishes. Ecological Monograph 48: 307–321.
Jayaram, K.C. (1999). The Fresh Water Fishes
of Indian Region. Narendra Publication, New Delhi, India, 551pp.
Johnsingh,
A.J.T. & D. Vickram (1987). Fishes of Mundanthurai Wildlife
Sanctuary, Tamil Nadu. Journal of Bombay Natural History &
Society 84(3): 526-533.
Johnson, J.A. (1999). Diversity and ecological structure of fishes in selected
streams/rivers in Western Ghats. PhD, Thesis submitted to Manonmaniam SundaranarUniversity, Tamil Nadu, 142pp.
Johnson, J.A. & R. Soranam (2001). A new species of HoralabiosaSilas from a Kerala stream of the western Ghats. Journal
of Bombay Natural History Society 98(3): 392-395.
Karr, J.R., K.D.Fausch, P.L. Angermeier,
P.R. Yant & I.J. Schlosser (1986). Assessing
biological integrity in running waters : a method and
its rationale Ill. Natural History Survey 5: 28.
Kottelat, M. & T.
Whitten (1997). Freshwater biodiversity in Asia with special reference to
fishes. The world bank Technical Report No.
343, Washington DC, 59pp.
Magurran, A.E. (1988). Ecological Diversity and Its Measurement. Croom Helm Publication, London, 167pp.
Menon, A.G.K. (1992). Conservation of freshwater fishes of Peninsular India. Final
report Ministry of Environment and Forests, 1989-92, India, 136pp.
Molur, S. & S. Walker (1998). Report
of the Conservation Assessment and Management Plan. Workshop on freshwater fishes of India. Zoo outreach Organization/CBSG, Coimbatore,
India, 156pp.
Nayar, M.P. (ed.)
(1996). “Hot Spots” of Endemic
Plants of India, Nepal and Bhutan. Tropical Botanical Garden, Trivandrum, 252pp.
Padhye, A.D., N. Dahanukar, M. Panigankar, M. Deshpande & D.Deshpande (2006). Seasonal
and landscape wise distribution of butterflies in Tamhini,
northern Western Ghats, India. Zoos’ Print Journal 21: 2175-2181.
Raghavan,
R., G. Prasad, A. Ali & B. Pereira (2008). Fish fauna of
River Chalakudy part of Western Ghats biodiversity
hotspot (south India) - patterns of distribution, threats and conservation
needs. Biodiversity Conservation 17: 3119-3131.
Rajan, S.
(1963). Ecology of the fishes of the river Pykara and Moyar (Nilgiris), south India. Proceedings of Indian
Academy of Science 58(B): 291-323.
Silas,
E.G. (1951). On a collection of fishes from anamalai and Nelliampathi hill ranges
(Western Ghats) with notes on its Zoogeographical significance. Journal
of the Bombay Natural History Society 49: 670-681.
Silas,
E.G. (1953). New fishes from the Western Ghats, with notes
on Puntius arulius(Jerdon). Records of Indian Museum 51:
27-38.
Talwar,
P.K. & A.G. Jhingran (1991). Inland Fishes of India and Adjacent Countries - Vol. 1 & 2.Oxford IBH Publication, New Delhi, 1158pp.