Deaths of overwintering Nanorana spp. tadpoles due to desiccation during check dam maintenance in a western Himalayan stream, India

Abstract

We report the deaths of overwintering tadpoles of Nanorana spp. during check dam maintenance events causing localised droughts along the Dhobhighat (Ringali Gad) stream, flowing through the Mussoorie Wildlife Sanctuary, Uttarakhand, India; and discusses the conservation issues and further research required in the scenario.

Full text

All amphibian life stages may be directly or indirectly
aected by drought, although many amphibians exhibit
plascity in the duraon of tadpole development, in response
to drought condions, with trade-os such as reduced body
condion, survival etc. (Cayuela et al., 2016; Yeung, 2021).
Droughts may be induced by human acvity such as when
check dams are drained for maintenance purposes. Check
dams are important civil engineering structures built for soil
conservaon, groundwater recharging and water extracon,
and are very common in Indian streams (Agoramoorthy et al.,
2008). Here, we report the rst observaons of the deaths of
overwintering tadpoles of two species of Nanorana during
check dam maintenance. It is known that check dams have
negave impacts on stream channel morphology (Fortugno
et al., 2017), water quality, velocity, and substrate neness
(Kang & Kazama, 2012), cause loss of larval microhabitat
(Thomas et al., 2019), and inuence the breeding ecology of
frogs (Lind et al., 1996). However the inuence of check dam
maintenance has been lile documented.
Our observaons concern two dicroglossid frog species.
The small paa frog Nanorana minica (Dubois, 1975) that is
associated with montane subtropical forests and streams
distributed in Nepal, Uarakhand and Himachal Pradesh at
1000–2400 m a.s.l. (Ohler et al., 2004; Bhaarai et al., 2020;
Frost, 2021). It is listed as Vulnerable on the IUCN Red List
and major conservaon threats are waterway management
and loss of habitat through forest clearance (Ohler et al.,
2004). The other species is the Himalaya paa frog Nanorana
vicina (Dubois, 1976) that is distributed in the Himalayan
front of India, north-central Pakistan from Kashmir,
Himachal Pradesh to Punjab, and Uarakhand ranging
from 2000–3000 m a.s.l. and is associated with montane
streams, springs, fountains and other running water within
open forest and grassland habitats (Ohler & Dua, 2004;
Frost 2021). Apart from morphological descripons and
other natural history records, lile is known of the larval
ecology of either species (Das & Dua, 2007; Sircar, 2010;
Banerjee et al., 2020; Gill et al., 2020; Jithin, 2021). Jithin
(2021) reported overwintering tadpoles of N. minica and N.
vicina from the western Himalaya, India. The overwintering
tadpoles feed on periphyton growing on check dam walls,
bedrocks, boulders, cobbles, leaf lier surface, submerged
logs in the pool; humus and animal carcasses; the check dam
pools also oer a temperature gradient (Boix-Fayos et al.,
2007: Banerjee et al., 2020; Jithin, 2021).
We recorded tadpole mortality at two check dam
maintenance events along the Dhobhighat (Ringali Gad)
stream, owing through the Mussoorie Wildlife Sanctuary.
This second-order stream ows through private resorts,
Herpetological Bullen 162 (2022) 23
The Herpetological Bulletin 162, 2022: 23–25
Deaths of overwintering Nanorana spp. tadpoles due to desiccaon
during check dam maintenance in a western Himalayan stream,
India
VIJAYAN JITHIN1* & ABHIJIT DAS2
1Post-Graduate Programme in Wildlife Science, Wildlife Instute of India, Chandrabani, Dehradun, Uarakhand, 248001, India
2Endangered Species Management Department, Wildlife Instute of India, Chandrabani, Dehradun, Uarakhand, 248001,
India
*Corresponding author e-mail: jithinvjyothis@gmail.com
hps://doi.org/10.33256/hb162.2325
SHORT COMMUNICATION
Figure 1. A. Example of a check dam pool with wider broad-crested
weir, and B. Overwintering tadpoles feeding on the periphytons
growing on the check dam walls in the Mussoorie Wildlife Sanctuary,
Uarakhand, India

24 Herpetological Bullen 162 (2022)
Vijayan Jithin & Abhijit Das
agricultural elds, and human habitaons and is dammed
in several places creang large check dam pool habitats.
These check dams were built during the 1960s and are
presently used for torrent control, water recharge and
extracng drinking water for Mussoorie town. The check
dams are managed by the Uarakhand Jal Sansthan and
a pump house is situated in the sanctuary (Management
Plan, 2010). Concrete or stone-mortar walls are present
with wider broad-crested weirs in the check dam pools.
Filtered water goes directly to a pump house via long
underground pipes from the check dams. The dams are used
by overwintering tadpoles, sh: snow trout (Schizothorax
richardsonii; Cyprinidae), stone loach (Schistura rupecula;
Nemacheilidae) and other aquac organisms (Management
Plan 2010; Jithin, 2021).
Annual maintenance of check dams is essenal. Water is
usually diverted from the original channel making the area
dry apart from a few shallow pools that act as refugia for
aquac organisms. Then broken walls are renovated, pipes
repaired and silt removed, aer which the boom is cleaned
and pebbles and small boulders from other natural pools are
deposited in the dam pool bed to facilitate water ltraon.
These maintenance acvies usually take 2–3 days to nish
and by this me, tadpoles, sh and crabs are either dead or
are predated by birds. During one such maintenance event
on 16 March 2021 at 12:32 h in a check dam pool (30° 28’
2.06” N, 78° 01’45.19” E, 1645 m a.s.l.) we quaned the
death of overwintering tadpoles. There were a total of ~150
tadpoles in an area of 2.5 m2 (Fig. 2 and Fig. 3D) of which 32
were found dead (21.3 %) and 61 alive, but stuck in the silt
(40.7 %).
We collected a representave sample of the dead
tadpoles and deposited it at the Wildlife Instute of India
Herpetofauna Collecon (N=14, WIIAD T-175-188). The
size of these tadpoles ranged from 25.32 to 63.4 mm (total
length) and stages from 26 to 36 (Gosner, 1960). We could
not quanfy the deaths of two species separately as eld
idencaon is dicult (Jithin, 2021). Apart from the
mortality of tadpoles, newly laid egg strings of Himalayan
toad Duaphrynus himalayanus were also found in the
dried stream bed.
On 20 March 2021 at 17:00 h, we recorded another
maintenance event in another stream poron (30°
27’57.90” N; 78° 01’46.40” E; 1751 m a.s.l.) where the death
of tadpoles resulted from deposion of silt, which was dug
out while cleaning a cement-lined tank built near the stream
for water ltraon (Fig. 3A-C, BHS video, 2022). The silt
ow made the water downstream turbid; we measured pH
and Total Dissolved Solids (TDS) using a portable pH meter
(Aquasole Digital Pen Type Meter, AM-P-PH) and a portable
EC/TDS meter (Aquasole Digital Pen Type Meter, AM-P-
EC) and Dissolved Oxygen (DO) levels using the modied
iodometric (Winkler) method (Jithin, 2021). These values
were compared with a dataset we generated from other
check dams and natural pools in the same stream (Jithin,
2021). All parameters were above mean [± 95 % CI] values
for the month of March (pH: 8.7 [8.356±0.063], DO: 10.145
[7.736±0.471] mg/L), but TDS showed a very high value (275
ppm), beyond the measurement range recorded (205–228
ppm) in the whole month from similar check dam pools.
Considering the large-scale killing of overwintering
tadpoles in check dam pools during maintenance, we
discourage complete draining of pools as this could lead
to the loss of refuge areas for the tadpoles. A reasonable
water volume should be le in the pools in such cases.
When complete draining operaons are required during
maintenance, aquac organisms (including tadpoles, sh,
crabs etc.) must be carefully transferred to nearby pools
to avoid large-scale deaths due to desiccaon. A standard
protocol for this procedure should be developed in
collaboraon with the Forest Department and Water Supply
Department.
Figure 2. Tadpole mortality during check dam maintenance and
renovaon - A. The pool before maintenance when the water ow
had been stopped and diverted, circles showing close-up images of
dead overwintering tadpoles, B. The check dam aer maintenance
Figure 3. Tadpole mortalies in a stream clogged with silt from the
maintenance of a check dam - A. Poron of stream clogged with
silt deposion, B. The cement-lined tank from where the silt was
removed, C. White circles showing dead overwintering tadpoles
of Nanorana spp. embedded in silt, D. Image showing the size
range among dead overwintering tadpoles of Nanorana spp. and
a dead stone loach Schistura rupecula sh at boom centre of the
photograph

Accepted: 26 June 2022
Herpetological Bullen 162 (2022) 25
Deaths of overwintering tadpoles due to desiccaon during check dam maintenance in India
ACKNOWLEDGMENTS
We thank the Chief Wildlife Warden, Uarakhand, for the
Research Permit (No: 2144/5-6, 21 January 2021) and WII
M.Sc. Dissertaon Grant for nancial support to VJ for
eldwork during which we made these observaons. We
thank Jeyaraj Antony Johnson for encouragement and
support; and Shanul Naual for assisng with the eldwork.
We are thankful for the logiscal support from the Wildlife
Instute of India (WII) grant-in-aid ‘Torrent frog project’, and
the Long-Term Ecological Observatories (LTEO) programme
by the Ministry of Environment, Forest and Climate Change,
Government of India and Centre for Ecological Sciences,
Indian Instute of Science, Bengaluru. We thank the Divisional
Forest Ocer, Mussoorie and Range Ocer, Mussoorie
Wildlife Sanctuary and Forest Department of Uarakhand
for facilitang our research by providing eldwork permits
and logiscal support.
REFERENCES
Agoramoorthy, G., Chaudhary, S. & Hsu, M.J. (2008). The
check-dam route to migate India’s water shortages.
Natural Resources Journal 48(3): 565–583.
Banerjee, K., Boruah, B. & Das, A. (2020). First record of
carrion feeding by tadpoles of Duaphrynus himalayanus
and Nanorana vicina from Western Himalaya, India.
Tropical Natural History 20(3): 268–271.
Bhaarai, S., Gurung, A., Lamichhane, B.R., Regmi, R.,
Dhungana, M., Kumpakha, B. & Subedi, N. (2020).
Amphibians and Reples of Chure Range, Nepal. President
Chure Terai-Madhesh Conservaon Development Board
and Naonal Trust for Nature Conservaon, Nepal, 60 pp.
BHS video (2022) Deaths of overwintering Nanorana spp.
tadpoles during check dam maintenance. Filmed by V.
Jithin. hps://youtu.be/cVZbP4qgdro.
Boix-Fayos, C., Barberá, G.G., López-Bermúdez, F. & Casllo,
V.M. (2007). Eects of check dams, reforestaon and land-
use changes on river channel morphology: Case study of
the Rogava catchment (Murcia, Spain). Geomorphology
91(1–2): 103–123.
Cayuela, H., Arsovski, D., Bonnaire, E., Duguet, R., Joly, P.
& Besnard, A. (2016). The impact of severe drought on
survival, fecundity, and populaon persistence in an
endangered amphibian. Ecosphere 7(2): e01246.
Das, I. & Dua, S.K. (2007). Sources of larval idenes for
amphibians of India. Hamadryad 31(2): 330.
Fortugno, D., Boix-Fayos, C., Bombino, G., Denisi, P.,
Quinonero Rubio, J.M., Tamburino, V. & Zema, D.A.
(2017). Adjustments in channel morphology due to land-
use changes and check dam installaon in mountain
torrents of Calabria (southern Italy). Earth Surface
Processes and Landforms 42(14): 2469–2483.
Frost, D.R. (Ed.). (2021). Amphibian Species of the World: an
Online Reference. Version 6.1 (accessed 17 December
2021). hps://amphibiansoheworld.amnh.org/index.
php. American Museum of Natural History, New York,
USA.
Gill, S., Rais, M., Saeed, M., Ahmed, W. & Akram, A. (2020).
The tadpoles of Murree Hills frog Nanorana vicina (Anura:
Dicroglossidae). Zootaxa 4759(3): 440–442.
Gosner, K.L. (1960). A simplied table for staging anuran
embryos and larvae with notes on idencaon.
Herpetologica 16(3): 183–190.
Hsu, J.L., Kam, Y.C. & Fellers, G.M. (2012). Overwintering
tadpoles and loss of tness correlates in Polypedates
braueri tadpoles that use arcial pools in a lowland
agroecosystem. Herpetologica 68(2): 184–194.
Jithin, V., Johnson, J.A. & Das, A. (2022). Inuence of check
dams on the acvity paern and morphometric traits
of overwintering tadpoles in the Western Himalaya.
Limnologica: 125992.
Jithin, V. (2021). Tadpoles with a trick: Overwintering Ecology
of Tadpoles in a Himalayan Stream, Uarakhand, India.
M.Sc. Dissertaon, Saurashtra University, Rajkot &
Wildlife Instute of India, Dehradun, India. xviii + 107 pp.
Kang, J.H. & Kazama, S. (2012). An ecological assessment of
a dammed pool formed by a slit check dam. Internaonal
Journal of River Basin Management 10(4): 331–340.
Lind, A.J., Welsh, H.H. & Wilson, R.A. (1996). The eects of a
dam on breeding habitat and egg survival of the Foothill
Yellow-legged Frog (Rana boylii). Herpetological Review
27(2): 62–67.
Management Plan. (2010). Management Plan of Mussoorie
Wild Life Sanctuary for the period (2010-11 to 2019-
20). Mussoorie Forest Division, Yamuna Circle, Forest
Department, Uarakhand, India. 230 pp.
Ohler, A. & Dua, S. (2004). IUCN Red List of Threatened
Species: Nanorana vicina. IUCN Red List of Threatened
Species. e.T58443A11781868. Accessed on 17 December
2021.
Ohler, A., Dua, S. & Shrestha, T.K. (2004). IUCN Red List of
Threatened Species: Nanorana minica. IUCN Red List of
Threatened Species. e.T58432A11780511. Accessed on
17 December 2021.
Sircar, G. (2010). Reproducve mode of Himalayan Paa frog -
Nanorana vicina. Unpublished M.Sc. Dissertaon, School
of Environmental Studies, University of Delhi, India. 33
pp.
Thomas, A., Das, S. & Manish, K. (2019). Inuence of stream
habitat variables on distribuon and abundance of
tadpoles of the endangered Purple frog, Nasikabatrachus
sahyadrensis (Anura: Nasikabatrachidae). Journal of Asia-
Pacic Biodiversity 12(2): 144–151.
Yeung, C.H.Y. (2021). Eects of drought on the larvae of the
short-legged horned toad, Boulenophrys brachykolos
(Inger and Romer, 1961) (Anura: Megophryidae), and the
lesser spiny frog, Quasipaa exilispinosa (Liu and Hu, 1975)
(Dicroglossidae) in Hong Kong. Reples & Amphibians
28(2): 352–354.