Artemia swarming -
Mechanisms and suggested reasons
J. Gulbrandsen-2001
Journal of Plankton Research, 23(7): 659-669
(from Current Contents)
Abstract :
The hypotheses are proposed that Artemia swarming may
be attributed to either density, age, feeding, salinity or light regime.
Subsequent tests indicate that swarming patterns were affected by light
regime, age and salinity, and that some of the observed patterns may serve
to facilitate foraging and respiration. Swarming as such was influenced by
density, age and previous feeding, but seemed unaffected by availability of
food and salinity. Swimming activity among young Artemia was higher inside
swarms than outside, while activity generally decreased as salinity
increased. It is further indicated that the horizontal distribution of
swarms is affected by salinity and depletion of Artemia over time, while the
actual generation of swarms is a result of predisposition as well as chance.
It is also demonstrated that young Artemia swarm more readily than older
animals and that there is a critical density for immediate swarm formation.
The results imply that swarming may reduce the availability of enriched
Artemia in larvicultures of fish, and that older Artemia form less coherent
swarms than younger Artemia and therefore serve better as live feed.
(NOAA, NW Fisheries Sci Ctr, 2725 Montlake Blvd E,
Seattle, WA 98112, USA)