Critical Thinking

The and its ecological aspects. Khatri et al.

The present study was carried out in a
pond at Nal village located at North-West of Bikaner District of Rajasthan
during September 2010 to November 2011. The main objective of the study was to
know the impact of abiotic factors on gastropods population. During the study three species of gastropods Gabbia orcula, Digoniostoma pulchella and Indoplanorbis exustus were recorded. Among these Digoniostoma pulchella show significant
correlation with pH, Gabbia orcula show
high significant correlation with water temperature and significant correlation
with Electrical Conductivity and Total Dissolved Solid of soil. Indoplanorbis exustus significantly
correlated with pH of water. Total gastropods population show significant
correlation with EC and TDS of soil. Desert waters always have high electrolyte
concenteration, but this study revealed that gastropods species in desert pond
undergo some adaptations and even survive during dry period of pond.

 

Keywords:
gastropods, pond, species, abiotic factor, desert

INTRODUCTION

Phylum
mollusca occupy diverse group of animals having different shape, sizes, habit
and habitat (Subba Rao, 1993). Around 8,765 species of fresh water molluscs
available in all over world, of which 284 species are reported from India and
adjacent countries. Among them, 171 species are of class gastropods
(Punithavela and Raghunathan, 2006) found in India. This is one of the
important components of aquatic food chain, acting as an energy flow bridge in
aquatic ecosystem because of detritus feeding habits. The ultimate extirpation
and extinction of molluscan populations have profound effects on the wider
ecosystem (Sharma et al. 2010).  Freshwater molluscs are the bioindicators of
freshwater pollution (Harman, 1974).

Fresh
water gastropods species have some economical and biological importance.
Economy of North-West of state partially based on dairy farming, and snails
also acts as intermediate hosts for Platyhelminthes parasites of animals,
birds, men, fishes and other trematode infection (Kandel, 1954). This caused
morbidity and mortality in livestock and creates economic burdens on farmers.

Past
studies on molluscs in Jodhpur was
carried out by Ray
& Mukherjee (1969), Rathore
& Bohra (1987). In Bikaner region Singh et al. (2007) and Rathore et al. (2007) studied growth rate in
some gastropods and its ecological aspects. Khatri et al. (2007) studied the incidence of trematode infestation in
snail Indoplanorbis exustus. Singh et al. (2010) studied the ecology and
diversity of prosobranch snails of Indian desert. Khanam (2012), Khanam &
Singh (2012 a, b) studied the ecology, population density and biometery of prosobranch
snails of desert region. Sharma et al. (2013) studied seasonal variation in population
density of gastropods.

The
aim of the study was to know the impact of abiotic factors on gastropods
population in desert pond in District Bikaner of Rajasthan.

MATERIALS AND METHOD

STUDY AREA

Rajasthan
the Desert state, lies between 2303′ to 30012′ N
latitudes and 69030′ to 78017′ E longitudes, having
largest area (132,139 mi2) among all Indian states. Bikaner, a part north-west
desert region having geographical location 28o N and 75o 17’E,
MSL 228 m. The present study was carried out from September 2010 to November
2011, in Nal pond located at E 730
12? and N 280 4? and MSL 229m in Bikaner
District of Rajasthan, covering an area of 2300 m2. During the study
period water depth of the pond was 6.09 meter. The pond remains dry in during
summer months May and June every year. It is situated in low land, and receives
rain water from surrounding areas. For Physico-Chemical analysis of water
sample APHA-AWWA-WPCF (1981) and Saxena (2001) were followed. Sampling was
conducted monthly as well as seasonally between 7 A.M. to 2 P.M. 

For
gastropod identification soil samples were collected from three location of the
pond with the help of quadrate having dimensions 25 × 20 × 10 cm and sieved
mesh size 2 mm, the methods prescribed by Saxena (2001) and Sharma et al. (2013). For qualitative analysis,
stereo microscope and for identification bull lens and standard keys (Subba
Rao, 1989) were followed.  Population
density was calculated by formulae prescribed by Saxena (2001).