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Title Effects of bottom trawling on the ecological integrity of macrobenthos off Veraval, Gujarat
 
Names Usha Bhagirathan
Panda, S.K.
Meenakumari, B.
Madhu, V.R.
Vaghela, D.T.
Date Issued 2012 (iso8601)
Abstract 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
to assess the impact of bottom trawling on the macrobenthic
fauna off Veraval coast. 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 groups of
fauna present were polychaetes, gastropods, bivalves,
scaphopods, amphipods, isopods, copepods, cumaceans,
ostracods, shrimps, crabs, squilla, balanids, foraminiferans,
octocorals, sipunculids, nemerteans, pogonophores,
pterobranchia, brittle stars and teleost fishes. A total of 81
species of polychaetes belonging to order Errantia (36 species)
and Sedentaria (45 species) were identified. The molluscs were
represented by 15 species of gastropods, 13 species of bivalves
and one species of scaphopod. One octocoral genus was also
identified. The abundance and biomass of the fauna were
recorded. The numerical density of macrofauna increased after
trawling, exposing them from their natural habitat. The numerical
density of macrofauna increased after trawl ban showing that
trawl ban is giving some respite to the fauna for rejuvenation.
The biodiversity indices were found to be significantly different
before and after experimental trawling at 15-20 m and 21-25
m. The ABC curve and w-statistic of the total macrofauna
showed that the fauna of the area studied were moderately or
grossly stressed. It was also possible to delineate the impact on
the fauna by MDS plots. The present study confirms the
deleterious effects of bottom trawlers on macrobenthos off
Veraval. Cataloguing the biodiversity of macrobenthos,
identification of indicator species and updating the new data
generated will aid in taking up steps towards conservation of
macrobenthos. Suggestions are made for the promotion of ecofriendly
gears and for conducting studies on appropriate
un-trawled control sites for comparative assessment.
Genre Article
Topic macrobenthos
Identifier J. Marine Biol. Assoc. India 54(1): 5-12