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International Journal of Marine Science 2014, Vol.4, No.23, 210-218
http://ijms.biopublisher.ca
211
The shores of west coast of India, particularly Kerala
coast are famous for its enthralling beauty and
lustrous greenery. From north to south the topography
of Kerala coast (abutted on the west by Arabian Sea)
is distinctive and alters abruptly. The coastline of
Kerala is 560km long and endures several alterations
in the near shore processes. The coast of Kerala
embraces a great variety of shores according to the
coastal geography and form of the substrate.
Sandy beaches are very dynamic environment. Wave,
wind action, grain size and tide amplitude is the most
important factors in their physical characterization
(Nybakken, 1993). The intertidal macrofaunal studies
have been great interest to the researchers during the
mid of the 20
th
century. Between 1920s and 1980s
shore studies were at its peak. Studies on soft shores
were made by Dahl, 1952, Morton and Miller, 1968,
Stephenson and Stephenson, 1972, Dayton, 1971,
Menge, 1976, Peterson, 1977. In 1983 two researchers
McLachlan and Brown have studied about the
patchiness of sandy beach macrofauna. By following
this Thrush, 1991, Morrisey et al., 1992 have been
studied about the distribution and abundance of
organisms including soft sediment macrofaunal
patchiness. In India Seshappa, 1953, Kurian, 1953
were the first to carry out detailed studies on the bottom
fauna of Madras, Malabar and Travancore. The other
significant works have been done by McIntyre, 1968,
Govindan Kutti and Nair, 1966.Recent studies have
been done on intertidal faunal, physical and climatic
interactions by Quadros et al. 2001, Misra and Kundu,
2005, Vaghela et al. 2010.
In recent times several studies have been fashioned by
the researchers to investigate community structure and
diversity of the intertidal zones of India (Dutta et al.,
2010; Singh Gohil and Kundu, 2012). In Kerala as a
coastal state of India an approach to the study on
intertidal zones and their diversity has been exhibiting
a declining trend. Limited studies have been
accomplished in various beaches of Kerala, mainly in
southern part (Travallion et al., 1970; Philip, 1970). It
would be a point of interest to explore new intertidal
zones along the coast of Kerala. This as a purpose in
mind, a pioneer study was undertaken on a sandy
beach situated in the northern part of Kerala along the
South West coast of India.
1 Results
1.1 Environmental factors
The important environmental characteristics were as
follows: Tides are semi diurnal type with maximum
tidal amplitude of 1.3m and a minimum of 0.01m.The
speed of the long shore current varied from 0.023m/s –
0.034m/s. Among water quality parameters
temperature, pH, and salinity of sand varied from
25-34
0
c, 25.5-32
0
c, 7-8.31, 6.48-8.32 and 17.5-33ppt,
10-33ppt at station 1&2 respectively. The particle size
showed dominance of sandy grains. The percentage of
sand varied from 37.4-99.2%.
1.2 Distribution and abundance of macro fauna
Thirty four species of macro invertebrates were
obtained from the stations during sampling. Among
the identified samples, gastropods, tanaids, and
polychaetes formed the dominant organisms in order
of faunal composition. The number of tanaids (43.4%)
was highest at all months at station1 when compared
to other groups whereas in station 2, gastropods
(45.54%) were dominant. The obtained species and
their abundance from high to low water mark are
given in Table 1. The distribution of organisms from
high tide to low tide marks was almost consistent
throughout the sampling. Around high tide zone of the
studied sites were characterized with burrows of
ocypode crabs. The amphipod (
Pontocrates altamarinus
)
occurred in a zone around mean high water at the time
of the collection and the sea star,
Astropectan
irregularis
was spotted at about these tidal levels at
both the stations.
On the rocky fragments of high tide zone, gastropods
especially
Littorina
sp
.
was abundant at station 2. The
mid region of the intertidal zone was characterized by
several polychaete worms, commonly
Scolelepis
(Scolelepis) squamata
at both the stations, whose
distribution extends down into the surf zone. Mid tide
region was blessed with different kinds of macrofauna,
Donax
sp., mole crab larvae, and other crustaceans,
like mysids etc. Low tide region was dominated by
echinoderms, polychaetes and some gastropods like
Turricula
and
Nassarius
sp
.
1.3 Macrofaunal diversity based on diversity indices
Spatially community indices varied from month to
month at any given station. Species diversity varied
from month to month at both the stations. Highest