Diversity of Zooplankton in River Siang of Arunachal Pradesh, India
Biplab Kumar Das1* and Devashish Kar2
1Department of Life Science and Bioinformatics, Assam University, India
2Department of Life Science and Bioinformatics and School of Life Sciences, Assam University, India
Submission: September 20, 2016; Published: October 20, 2016
*Corresponding author: Biplab Kumar Das, of Life Science and Bioinformatics, Assam University, Silchar- 788011, Assam, India.
How to cite this article: Biplab K D, Devashish K. Diversity of Zooplankton in River Siang of Arunachal Pradesh, India t. Ocean & fish Open Access J. 2016; 1(2): 555558. DOI: 10.19080/OFOAJ.2016.01.555558
Zooplankton is a group of micro-organisms which do not have strong power of locomotion and usually move by being drifted by water current. In up-stream region of River Siang, they were less in numbers in most of the sampling sites. During the study period, 24 different genera of zooplankton were recorded from the River Siang. The recorded zooplanktons were classified into 5 different groups, among which, Protozoans were represented by 6 genera (22%); Rotifera by 7 genera (30%); Cladocera by 5 genera (22%); Ostracoda by 1 genus (4%) and Copepoda were represented by 5 genera (22%).
Keywords: Zooplankton; Seasonal Variations; Diversity; River Siang; Arunachal Pradesh
Limnology is an inter-disciplinary science which involves a great deal of detailed field as well as laboratory studies to understand the structural, functional aspects and problems associated with the fresh water environment, from a holistic point of view . Aquatic biodiversity is threatened primarily by human abuse and mismanagement of both living resources and the ecosystems that support them. Most of the ponds are getting polluted due to domestic waste, sewage, industrial and agricultural effluents. The requirement of water in all lives, from micro-organisms to man is a grave problem today because all water resources have reached a point of crisis due to unplanned urbanization and industrialization.
Floodplain lakes are common features of the river systems in North East India. The floodplain lake of Assam is a highly productive system producing around 100 kg ha1yr1 from Indian reservoirs . The floodplain lakes form an important component of inland aquatic resources of northeastern India, exhibit significant fishery potential and are mainly located in the states of Assam. Little is known so far about biological productivity of these interesting ecotones in general, and about composition, abundance and ecology in zooplankton in particular  from certain floodplains lake of Assam. While
Sharma  studied their ecology in Deepor Beel (Ramsar Site), some of the workers who made significant contributions in zooplankton and phytoplankton are Edmondson, Boney, Hobro and Willen, Pennak, Ramakrishnan and Sarkar, Bhati and Rana, Islam et al., Acharjee et al., Daimari et al., Kar and Barbhuiya, Salve and Hiware, Nikam, Veerrendra et al, Singh and Sharma, Rajagopal et al. [5-19]
The River Siang is the largest river of Brahmaputra river system, originating from Chema Yungdung Glacier near Kubi at 5150 m in Tibet. Popularly known as Tsang-Po in Tibet, it flows in the West–East direction. After traversing a distance of about 1625 km in Tibet, it takes a turn in south direction, enters the territory of India near Tuting in the Upper Siang district of Arunachal Pradesh, and flows through North–South direction in East Siang district towards Assam and finally merges with Lohit and Dibang in Assam, becoming the mighty River Brahmaputra (Das et. al. 2014a, Das et. al. .2014b, Das and, 2015) [20-23].
Plankton samples, from the River Siang, were collected using plankton net made of bolting silk cloth (Nylobolt No 25 standard) having a mesh size of 0.2 mm. The plankton net was first tied to a weight and attached to a stick marked at 50 cm.
The net was allowed to dip till it reached the mark and dragged
for a distance of 24.39 m. The plankton samples were collected
by filtering 6 litres of water from the studied site in the river
and preserved in 5 % formalin in 50 ml capacity plankton
sampling tube. The planktons were studied by the Lackeys drop
method under a LABOMED- make binocular light microscope in
the laboratory and first sorted out into different groups using
a Microscope; detailed taxonomic identification was done with
the help of following standard keys and literature. Counting was
done by using Sedgwick- Rafter Counting Cell [24-27].
River Siang is Hill-Stream first order river; has colluvial
(landslide from adjacent hill slopes delivering sediments and
organic matter) valley segment and pool-riffle type of reach.
This reach type is most commonly associated with small to
mid-size streams and is a quite prevalent type of reach in the
rheophilic zones. On the other hand, runs are generally laminar
flow of water with sandy substratum. Pools, riffles and runs
are generally found to dominate the micro-habitat type with
frequent occurrence of trench pools. This river is said to be more
entrenched based on V-shaped valley segment. The substrate
type has been found to be dominated by gravels and cobbles
with frequently-occurring quite large number of boulders and
some bed rocks.
In River Siang, it had been observed that Rotifers were
found to be dominant group; while, Ostracoda were found to be
a less abundant group during the whole study period (Figures
1-3). The study revealed that the increase in the number of
zooplankton was in accordance with the temperature and its
habitat. This study also showed that zooplankton species survive
in the neutral condition in River Siang. It has been observed that
fish density and plankton number are having relationship with
water temperature which is in conformity with Chakravarty
et al. . Variation in bio chemical activity, velocity, volume,
substrate, cover, water sources and a number of additional
features operating seasonally  may be possible factor for
variation in temperatu
During monsoon season, adverse effect on planktonic forms
has been recorded particularly at certain gradient zones. It is
apparent that sudden influx of water in the river during that
season should be the causative factor for such phenomenon.
The same view was also observed by Barner . Occurrence
of zooplankton in rapids and upstream and some portion of mid
stream of River Siang have been found to be very less. It has been
observed that increase in water current and turbidity affects
In River Siang, the highest population of zooplankton
(453) is found in monsoon season, while the lowest (296) in
the winter season. Species richness (S) was highest (24) in
monsoon and lowest as (20) in both winter and pre-monsoon
seasons. Species diversity index (H/) recorded between 3.004 and 2.711; maximum in post monsoon and minimum in winter.
Simpson index of dominance (D) ranged between 0.07843 and
0.5644 maximum in winter and minimum in post monsoon.
Simpson index of diversity (1-D) recorded 0.9436 post monsoon
and 0.9216 in winter season. Evenness (e^H/S) ranged between 0.8766 and 0.7523; maximum in post monsoon and minimum in
winter seasons. Margalef index (D) was recorded between 3.761
and 3.268; maximum in monsoon and minimum in pre-monsoon
seasons (Tables 1-3) .
The study revealed that the increase in the number of
zooplanktons was in accordance with temperature and its
habitat. This study also showed that zooplankton species
survive in neutral condition. The status of the River Siang could
said to be eutrophic as indicated by the diversity of zooplankton;
it can be concluded that the zooplankton are enough to enrich
the water quality of River Siang and suitable for fish production.