Effect of photophase on feeding rhythm
The optimal illumination intensity for feeding varies
with fish species. For example, Ellertsen et al.
(1981) reported that the larval Atlantic cod (Gadus
morhua L.) could ingest the nauplius of Artemia at
illumination intensity for 0.l-0.4 lx. He and Yu (1984)
revealed that the largest feeding intensity of Engraulis
enerasicholus and young Aspiusa aspiusa (Linnaeas)
occurred at 10-1 lx, when the larval would sink to the
water bottom. Under natural conditions, rhythmic
changes of feeding intensity were demonstrated in
many larval and young fish (Zhang, 1965; Li et al.,
1980; Wang, 1990). The change of feeding intensity is
related to illumination intensity, amount of dissolved
oxygen and the diurnal change of water temperature.
Among these factors, the influence of the illumination
intensity plays a major role as it directly affects the
amount of dissolved oxygen and indirectly periodic
change of water temperature.
Acknowledgment