WA Native Fish Strategy: Freshwater fish distribution database and
FRESHWATER FISH SURVEY OF HOMADOLA-NAKIYADENIYA …
Transcript of FRESHWATER FISH SURVEY OF HOMADOLA-NAKIYADENIYA …
FRESHWATER FISH SURVEY OF HOMADOLA-NAKIYADENIYA ESTATES, SRI LANKA.
Prepared by Hiranya Sudasinghe BSc. (Hons) Zoology, M.Phil. reading (University of Peradeniya)
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INTRODUCTION
The diversity of freshwater fishes in Sri Lanka is remarkably high, with a total of 93 indigenous
fishes being recorded from inland waters, out of which 53 are considered to be endemic
(MOE, 2012; Batuwita et al., 2013). Out of these, 21 are listed as Critically Endangered, 19 as
Endangered and five as Vulnerable in the National Red List (MOE, 2012). In addition, several
new species of freshwater fishes have been discovered in the recent past which have not yet
been evaluated for Red Listing (Batuwita et al., 2017; Sudasinghe 2017; Sudasinghe &
Meegaskumbura, 2016; Sudasinghe et al., 2016). Out of the 22 families that represent the Sri
Lankan freshwater ichthyofauna, the family Cyprinidae dominates, representing about 50%
of the species, followed by the families Gobiidae, Channidae and Bagridae, which represent
seven, five and four species, respectively. The remainder of the other families are each
represented in Sri Lanka by three species or less.
Four major ichthyological zones, viz. Southwestern zone, Mahaweli zone, Dry zone and the
Transition zone were identified by Senanayake and Moyle (1982) based on the distribution
and the endemism of the fish. The Southwestern zone shows the greatest diversity, followed
by the Mahaweli zone, with the least diversity observed in the Dry zone. About 60% of the
freshwater fishes occur both in the dry and the wet zones of the island while the rest are more
or less restricted to the wet zone. Of the endemic fishes, more than 60% are restricted to the
wet zone of the island while about 30% occur in both the dry and the wet zones. Thirteen
species are considered to be micro-endemics, with highly restricted distributions within the
island.
As part of my ongoing research, I first visited the Homadola estate on 26/Sep/2017 to sample
a recently described species: Devario udenii. Upon my first visit, I was invited to carry out an
extensive study on the freshwater fish fauna to facilitate the ongoing RSPO projects being
carried out in these estates. Thus, herewith I provide the information gathered during my
brief field sampling and recommendations to enrich the freshwater habitats inside these
estates.
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MATERIALS AND METHODS
Field work was carried out on 26/Sep/2017 and 15-17/Dec/2017 in aquatic habitats inside the
Homadola and Nakiyadeniya estates belonging to the Watawala Plantations PLC. Habitat
characteristics of the sampled sites are provided in Table 1. Sampling sites were selected to
represent a variety of different habitat characteristics (Appendix 1). Garmin® Map GPS 64 was
used to obtain GPS coordinates of the locations. Fishes were observed underwater using a
mask and a snorkel where applicable and netting was done either using a drag net (3 m × 1.5
m) and hand net (0.5 m ×0.5m). Fishes were photographed underwater using Olympus TG4
camera and some were captured and photographed in a glass aquarium using a Canon 7D
camera with a 100 mm macro lens.
Table 1. Sampling localities and habitat characteristics of sites at Homadola and
Nakiyadeniya estates
Habitat A B C D E F
Local name Homadola
estate
Homadola
estate
Homadola
estate
Madola,
Homadola estate
Nakiyadeniya
estate
Seethala dola,
Nakiyadeniya
estate
GPS
coordinates
6.2137,
80.34956
6.21576,
80.34361
6.22542,
80.33901
6.22953,
80.36664
6.16996,
80.35834
6.15178,
80.31023
Habitat type Large stream Large stream Small river Small river Small streams stream
Surrounding Disturbed
secondary
forest
Disturbed
secondary
forest/ palm
oil
Disturbed
secondary
forest/tea
Undisturbed
secondary forest
Anthropogenic
/palm oil
Palm oil
Flow rate Fast Moderate Moderate/Fast Moderate/Fast slow Moderate/
Fast
Bottom
substrate
Pebbles/sand
/boulders
Pebbles/sand Pebbles/sand/
boulders
Boulders/pebbles Sand/silt Pebbles/sand/
boulders
Canopy
cover
50-70% 50-60% 50-60% 50-70% open 20-30%
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RESULTS
A total of 29 species of freshwater fishes belonging to 12 families were recorded during the
survey (Table 2). Family Cyprinidae dominated with 15 species followed by family Gobiidae
(three species) and Osphronemidae (two species). The rest of the families Cobitidae,
Nemacheilidae, Bagridae, Claridae, Belonidae, Aplocheilidae, Channidae, Mastacembelidae
and Poecilidae were represented by a single species each (Figure 1). Out of the 29 species
recorded, 16 species were endemic. The freshwater fish species recorded included a Critically
Endangered species (Sicyopterus griseus), eight Endangered species (Pethia cumingii, Pethia
nigrofasciata, Puntius kelumi, Puntius titteya, Systomus pleurotaenia, Mystus ankutta,
Aplocheilus werneri, and Sicyopus jonklaasi), a Vulnerbale species (Garra ceylonensis) and an
exotic species (Poecilia reticulata: Figure 2).
In terms of species richness, the most number of species were recorded at Habitat C (19
species) and the least number of species were recorded at Habitat B (4 species: Figure 3).
Figure 1. Freshwater fish families recorded during the fish survey.
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Table 2. List of freshwater fish species recorded in the streams of Homadola and
Nakiyadeniya estates during the survey. Species in bold-face are endemic.
Family
Species Common Name Habitat Conservation Status
A B C D E F
Cyprinidae Dawkinsia singhala Sri Lanka
Filamented barb
- - + + + - Least Concerned
Cyprinidae Devario udenii
Udenii’s Danio + + + + - - Not Evaluated
Cyprinidae Garra ceylonensis Sri Lanka Stone
Sucker
+ - + + - + Vulnerable
Cyprinidae Pethia cumingii
Cuming’s Barb - - + - - - Endangered
Cyprinidae Pethia nigrofasciata
Black Ruby Barb - - + + - - Endangered
Cyprinidae Puntius bimaculatus
Red-side barb - - - - + - Least Concerned
Cyprinidae Puntius dorsalis Long-snouted
barb
+ + + + + - Least Concerned
Cyprinidae Puntius kelumi
Kelumi’s barb - - + + - - Endangered
Cyprinidae Puntius titteya
Cherry barb - - - - + + Endangered
Cyprinidae Puntius vittatus
Silver barb - - - - + + Least Concerned
Cyprinidae Rasbora dandia Broad-lined
rasbora
- + + + + + Least Concerned
Cyprinidae Rasboroides
pallidus
Golden rasbora - - - + - - Not Evaluated
Cyprinidae Systomus
pleurotaenia
Black-lined barb + + + + - - Endangered
Cyprinidae Systomus sarana Olive barb - - + - - - Least Concerned
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Cyprinidae Tor khudree
Mahseer + - + + - - Near Threatened
Cobitidae Lepidocephalichthys
thermalis
Common spiny
loach
- - - - + - Least Concerned
Nemacheilidae Schistura
notostigma
Banded mountain
loach
+ - + + - + Near Threatened
Bagridae Mystus ankutta
Dwarf catfish - - + - - - Endangered
Claridae Clarias brachysoma
Walking catfish - - - - + - Near Threatened
Belonidae Xenentodon cancila Freshwater gar
fish
- - + - - - Near Threatened
Aplocheilidae Aplocheilus werneri Werner’s killifish
- - - - + + Endangered
Gobiidae Awaous
melanocephalus
Scribbled goby + - + + - + Least Concerned
Gobiidae Sicyopterus griseus
Stone goby - - + - - - Critically Endangered
Gobiidae Sicyopus jonklaasi Lipstick goby
+ - + + - - Endangered
Osphronemidae Belontia signata Combtail
+ - + + + + Near Threatened
Osphronemidae Pseudosphromenus
cupanus
Spike-tailed
paradise fish
- - - - + - Least Concerned
Channidae Channa gachua
Brown snakehead - - - - + - Least Concerned
Mastacembelidae Mastacembelus
armatus
Marbled spiny eel - - + + - - Least Concerned
Poecilidae Poecilia reticulata Guppy
- - - - + - Exotic
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Figure 2. Conservation status of freshwater fish species recorded during the survey.
Figure 3. Species richness in different sampling localities during the survey.
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DISCUSSION
Recording of 29 species of freshwater fish species based on the brief survey carried out during
only four days of field work, suggest that the aquatic habitats are quite diverse and rich in
terms of freshwater fishes. Though not recorded from this survey, there are several other
confirmed records of some freshwater fish species in the collection of the Wildlife Heritage
trust (WHT) now at the National Museum of Sri Lanka recorded from this area. This include a
Critically Endangered species called Lepidocephalycthys jonklaasi (Jonklas’s loach) recorded
from “Udugama ela” (Figure 4). This species is likely recorded around the Habitat C in small
shady streams flowing to the site that I sampled. Thus, close inspection in small streams
around habitat C is highly recommended to confirm the presence of this species.
Lepidocephalycthys jonklaasi is recorded only in few localities in the lowland wet zone mainly
around rainforests and prefers slow flowing, well shaded, small streams with clear water.
Thus, if this species is recorded from the small streams inside the Homadola estates, an in-
situ conservation plan can be initiated inside the estate.
Figure 4. WHT30661, A specimen of Lepidocephalycthys jonklaasi collected from “Udugama
ela” in 2000.
Other freshwater fish species not recorded during my brief survey but are known to occur
around Homadola area include Channa orientalis (Smooth breasted Snakehead: Endemic,
Vulnerable), Ompok argestes (Mottled Butter catfish: Endemic, Not evaluated) and
Heteropneustes fossilis (Stinging Catfish: Native, Least Concerned). If these species are also
taken into account, the total number of species recorded around Homadola-Nakiyadeniya
sites would be 33 species of which 19 would be endemic. If more number of sampling
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localities and night sampling were carried out, it is likely that several more species of
freshwater fish are to be recorded from Homadola-Nakiyadeniya estates.
When comparing the species richness and endemicity at different sampling sites, habitats C
and D harbored most number of species as well as most number of endemic species. Both
these habitats had a relatively undisturbed buffer zone consisting of secondary rainforest.
These habitats also harbored the most number of threatened species (Figure 5).
Figure 5. Endemicity and number of threatened species recorded in the different habitats
sampled.
Sicyopterus griseus, one of the rarest species of gobies in Sri Lanka were recorded at Habitat
C. It is a Critically Endangered species recorded only from few localities within the south-west
region of Sri Lanka. They are found only in the clear, fast flowing, with rocky boulders, usually
in large streams or rivers. This species has an amphidromous life cycle, in which the adults
grow and reproduce in freshwater, the larvae hatch in freshwater but migrate downstream
to the sea and again migrate back to freshwater as adults. Therefore the continuation of an
uninterrupted flow of the water bodies are critical to the life cycle of this species.
The record of Rasboroides pallidus at habitat D is also important highlighting the pristine
nature of these habitats. Rasboroides pallidus are very sensitive to changes in water quality
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and are found only in clear, well shaded streams around lowland rainforests. There are only
two endemic genera of freshwater fishes in Sri Lanka and the genus Raboroides is one of
them.
The population of hill stream loaches of the genus Schistura, I recorded from the habitat F at
Seethala-dola in Nakiyadeniya is quite different from the typical Schistura notostigma that is
found in fast flowing streams in Sri Lanka (Figure 6). I am currently examining and comparing
the samples I’ve collected with the reference specimens. If in fact, I conclude this population
to be a hitherto unknown new species and describe it in a scientific article, I strongly
recommend to carry out an in-situ conservation program and an ecological study for this
species. As it is found outside any protected area, a proper conservation plan would ensure
its survival.
Figure 6. A, population of Schistura recorded from Seethaladola, Nakiyadeniya; B, typical
coloration of Schistura notostigma.
The occurrence of Guppy (Poecilia reticulata) in the site E were mainly disturbed habitats
close to anthropogenic activities. Guppies are able to survive in very harsh conditions and
their high rate of reproduction ensures their survival even in extreme conditions. The native
species recorded at site E, too were mainly the most common species excluding Puntius
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titteya and Aplocheilus werneri that are encountered in diverse habitats. Though recorded,
the abundance of Puntius titteya and Aplocheilus werneri at site E was comparably low.
In conclusion, there is a remarkable species richness of freshwater fish species observed in
the habitats sampled at Homadola and Nakiyadeniya estates including several rare, endemic
and threatened species. Few more species are likely to be added to the list, if more field
sampling is carried out.
ACKNOWLEDGMENTS
I am thankful to Mr Binesh Pananwala (CEO), Mr Chamika Naranapitiya (DGM- South) and
the staff (Mr Ruwan Gunaratne, Mr Malinda Jayasundara, Mr Dinuka Lanka and others) of
Watawala Plantations PLC, Sunshine Holdings for providing me the opportunity to carry out
field work at Nakiyadeniya and Homadola estates and for their kind hospitality during my
visits. I am grateful to Mr Kumudu Wijesooriya and Mr Tharindu Ranasinghe for providing
me with assistance during the field work.
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GENERAL RECOMMENDATIONS
1. Maintain a buffer zone of at least 2-5 m on both sides of aquatic habitats found inside
the estates as a proportion to the width of the aquatic habitat.
2. Buffer zones to be planted with native vegetation in disturbed habitats.
3. Planting species of Lagenandra (“Ketala”) and Aponogeton (“Kekatiya) along the
marginal vegetation of disturbed habitats which will provide suitable breeding
grounds and hiding places for most of freshwater fish species.
4. Identify Aplocheilus werneri, and Puntius titteya, as the key species found in slow
flowing, clear, shady, small streams. They are sensitive species and their presence in
such habitats indicate favorable habitat for most of other species as well.
5. Identify Rasboroides pallidus as the key species found in slow flowing, clear, shady,
large streams/rivers. Rasboroides pallidus is a very sensitive species and its presence
in such habitats indicate favorable habitat for most of other species as well.
6. Identify Systomus pleurotaenia, Sicyopterus griseus, and Sicyopus jonklaasi as the key
species found in fast flowing, clear, open, large streams/rivers. Systomus pleurotaenia
is a sensitive species and its presence in such habitats indicate favorable habitat for
most of other species as well, while Sicyopterus griseus, and Sicyopus jonklaasi are
habitat specialists found only in fast flowing, rocky regions of the streams/rivers.
7. Investigate the presence/absence of the Critically Endangered Lepidocephalycthys
jonklaasi in the slow flowing, clear, shady, small streams inside the estates, and if
present, plan an in-situ conservation plan for the species.
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REFERENCES
Batuwita, S., Silva, M. & Edirisinghe, U. (2013) A review of the danionine genera
Rasboroides and Horadandia (Pisces: Cyprinidae), with description of a new species
from Sri Lanka. Ichthyological Exploration of Freshwaters, 24 (2), 121-140.
Batuwita, S., de silva, M., & Udugampala, S. (2017) A review of the genus Devario in Sri Lanka
(Teleostei: Cyprinidae), with description of two new species. FishTaxa, 2(3), 156-179.
MOE (Ministry of Environment) (2012) The National Red List 2012 of Sri Lanka; Conservation
Status of the Fauna and Flora. Colombo: Ministry of Environment.
Senanayake, F.R. & Moyle, P.B. (1982) Conservation of freshwater fishes of SriLanka.
Biological Conservation, 22 (3), 181-195.
Sudasinghe, H. (2017) Schistura madhavai, a new species of hill-stream loach from Sri Lanka,
with redescription of S. notostigma (Teleostei: Nemacheilidae). Zootaxa, 4311(1), 96-
110.
Sudasinghe, H., & Meegaskumbura, M. (2016) Ompok argestes, a new species of silurid catfish
endemic to Sri Lanka (Teleostei: Siluridae). Zootaxa, 4158 (2), 261-271.
Sudasinghe, H., Pethiyagoda, R., Maduwage, K., & Meegaskumbura, M. (2016) Mystus nanus,
a new striped catfish from Sri Lanka (Teleostei: Bagridae). Ichthyological Exploration
of Freshwaters, 27 (2), 163-172.