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Title Impact of bottom trawling on sediment characteristics - A study along inshore water off Veraval coast, India
 
Names Usha Bhagirathan
Meenakumari, B.
Jayalakshmy, K.V.
Panda, S.K.
Madhu, V.R.
Vaghela, D.T.
Date Issued 2010 (iso8601)
Abstract The present communication is a study
on the impact of bottom trawling on the sediment
characteristics along Veraval coast, which is the
largest trawler port of India. Experimental bottom
trawling was conducted from MFV Sagarkripa
at five transects of water depths 15–20 m, 21–
25 m, 26–30 m, 31–35 m and 36–40 m in commercial
trawling grounds. Trawling was conducted
for 12 months in a span of 15 months (September
2005–November 2006) excluding the trawl ban period
(June to August). The sediment texture was
analysed by pipette analysis and organic matter by
wet oxidation method. The variations in organic
matter and sediment texture were prominent between
the stations selected at different depths.
The sedimentary organic matter exhibited variations
with different water depths and seasons.
The organic matter content decreased with depth.
Experimental trawling considerably reduced the
organic matter content at all depths. Continued
and incessant trawling operation can cause even
more drastic reductions, where organic matter
(OM) content is already very small. The sand
proportion showed depth-wise variation; but seasonal
and trawling effect was not significant showing
highest values at 36–40 m depth. The silt
proportion did not exhibit significant depth-wise
variation. The seasonal variation of silt was significant
whereas trawling effect imparted to silt
was not evident. Trawling has no significant effect
on clay concentration. But seasonal variation had
great influence on the clay distribution and indicated
significantly high depth–season interaction.
The sediment of the study area was predominant
in silt proportion. It was observed that the
seasonal/natural variations were more prominent
masking the trawling effect on silt.
Genre Article
Identifier Environ. Monitor. Asess. 160:355-369