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Diurnal variations in the vertical distribution and abundance of zooplankton in the continental shelf waters off Cochin during April 1991

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Title Diurnal variations in the vertical distribution and abundance of zooplankton in the continental shelf waters off Cochin during April 1991
 
Creator Selvaraj, G S D
Mathew, K J
Varghese, Molly
 
Subject Zooplanktons
 
Description The present study is based on zooplankton samples collected by vertical hauls
from 0-30, 30-60 and 60-90 m depths from a 100 m depth station in the continental
shelf (09° 44' N, 75° 42*8) off Cochin for two days at three hourly interval. The mean
displacement volume of zooplankton biomass at these depth zones were 6.24, 6.70
and 6.07 ml/100 m water while their numerical counts were 14490,13355 and 11290
no/100 m respectively. The overall mean volume (ml) and number per 100 m in the
endre water column (0-90 m) were 6.34 and 13045 respectively and were distributed
as 5.89 ml and 11715 no/100 m^ in the daytime and 6.79 ml and 14376 no/100 m^
during night hours respectively. The biomass was dominated by copepods (75.6%),
decapod larvae (12.2%), chaetognaths (6.5%) and appendicularians (2.4%) in April.
In general, copepods, decapod larvae and appendicularians showed increasing trend
in number from the bottom (60-90 m) to the surface layer (0-30 m); chaetognaths,
medusae, pteropods, heteropods, salps and doliolids were distributed more in the
middle zone (30-60 m); while ostracods and planktonic polychaetes were more in the
bottom zone (60-90 m). Distribution of amphipods and ostracods indicated significant
diurnal vertical migration. The phenomenon of mid- night sinking was noticed
in the case of copepods, chaetognaths, appendicularians, medusae, siphonophores,
salps and doliolids.
 
Date 1996
 
Type Conference or Workshop Item
PeerReviewed
 
Format application/pdf
 
Language en
 
Identifier http://eprints.cmfri.org.in/5150/1/15.pdf
Selvaraj, G S D and Mathew, K J and Varghese, Molly (1996) Diurnal variations in the vertical distribution and abundance of zooplankton in the continental shelf waters off Cochin during April 1991. In: Second workshop on scientific results of FORV Sagar Sampada, 15-17 February 1994, Kochi.