Net avoidance behaviour among larval, juvenile and adult euphausiids

Mathew, K J (1988) Net avoidance behaviour among larval, juvenile and adult euphausiids. Journal of the Marine Biological Association of India, 30 (1&2). pp. 93-98.

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Abstract

During the present investigations all attempt was made to assess the degree of net avoidance capability of euphausiids at the larval, juvenile and adult levels. The study was faciliated by a series of zooplankton samples collected during both day and night from 5 m above bottom to the surface. In spite of sampling from' almost' bottom, striking difference in the avilability was observed especially for the adults of several species being, in most of the cases, more in the night samples. The results obtained have led to derive some conclusions on the behaviour of euphausiids. The present studies indicated that as far as the larvae were concerned, the degree of variation in abundance was least between day and night and this speaks for their inability to avoid an approaching net in the da> light. However, marked increase in number was osbserved with the juveniles in the night samples. A night time increase by 57 times was observed with the juveniles of Euphausia diomedeae, a surface shoaling species, whereas Stylocheiron affine, a mesopelagic species showed an increase by 0.21 times only in the night samples. The adults also showed marked difference of occurrence between day and night. An increase in number by 65.7 times was noticed in the night abundance of Euphausia sibogae, again a surface swarming species, over the day time occurrence. However, in the case of S. affine the night time increase was of the magnitude of 2.3 times only.

Item Type:Article
Uncontrolled Keywords:euphausiids
Subjects:Marine Biology > Phytoplanktons
Divisions:CMFRI-Cochin > Fishery Environment
ID Code:1083
Deposited By:Geetha P Mrs
Deposited On:17 Jun 2010 17:40
Last Modified:17 Jun 2010 17:40
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