Temporal variation in the hydrography and biodiversity of the Cochin backwaters of Puduveypu region.
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Date
2011
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Department of Fishery Hydrography, College of Fisheries, Panangad
Abstract
The study was carried out to find out the temporal
variation in the hydrography of the Cochin backwaterS of
Puduveypu region and to find out the richness of the biodiversity
of the area. The study was conducted from April, 2010 to Apil,
2011. The present study was carried out to find out the temporal
variation in the hydrography of the Cochin backwater of
Puduveypu region and to find out the richness of the biodiversity
of the area.
The value of salinity in the backwaters of Puduveypu
showed a wide fluctuation. The maximum value was recorded in
the second half of January. The salinity showed considerable
reduction during the period of March-April, 2011 due to Premonsoon
showers. . Water temperature showed peak values
during pre-monsoon period and with the onset of monsoon the
value decreased. High pH was observed during the monsoon
season while low values were observed during N.E. monsoon
and pre-monsoon period. Alkalinity showed an increasing trend
during the pre-monsoon, post monsoon and N.E. monsoon
seasons but a decreasing trend was observed during monsoon
season. Total hardness ranged between 22.22 mg CaCO3/l and
710.01 mg CaCO3/l. Dissolved oxygen showed high values
during monsoon and post monsoon period. During the N.E.
monsoon period the dissolved oxygen showed a decreasing
pattern and reached a minimum of 2.1mg/l in the second half of
February. The higher values of nitrate-N were observed during
post monsoon and monsoon season. Seasonal variation of nitrite
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was not that much pronounced. The phosphate value ranged
between 2.2 μg at/l and 5.8 μg at/l during the study period. The
maximum value of silicate-Si was recorded during the last phase
of the monsoon.
Turbidity ranged between 11.11 NTU and 40.4 NTU. It
showed a negative correlation with transparency. Transparency
value of the study region falls within a range of 30 cm. to 47 cm.
Primary productions showed a wide range from 32 mgC/m3/day
to 3707 mgC/m3/day. The highest value of chlorophyll was
observed during the second half of July and the minimum value
was observed during the second half of October.
The sediment pH value ranged between 7.02 and 8.3 with
an average of 7.78. The analysis revealed that sediment of the
Puduveypu region contains maximum sand followed by silt and
clay.
Mangrove species like Rhizophora mucronata,
Rhizophora apiculata, Rhizophora conjugate, Brugiuera
cylindrical, Brugiuera gymnorhiza, Sonerasia caseolaris,
Sonerasia alba, Avicennia officianalis, Exocearia agallocha,
Acanthus ilicifolius, Clerodenterum innerme, Premma latifolia,
and Acrostichum aureum were found in the study area. ,
Avicennia officianalis contribute 70% of the total population of
mangrove. Penaeus monodon, P. indicus, Metapenaeus dobsonii,
M. monoceros, Feneropenaeus indicus, Penaeus semisulcatus,
Macrobrachium equidens, M. idella have been identified from
the study area. Crabs in the study area include Scylla serrata,
Scylla tranquebarica, Thalamita creneta, Charybdis annulata,
Sesarma quadratum, Uca vocans. Bivalves includes Lamellidens
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sp., Villorita Sp. and Cirriped in the study region include
Balanus. 36 species of finfishes were collected during the study
period. The fishes can be categorized into 10 order and 26
families.
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173075