Vertical migration of zooplankton groups in an Eutrophic bay, Dekhaila harbor, Alexandria, Egypt
Diel vertical migration of different zooplankton groups in Dekhaila Harbor was studied monthly from May 2003 to April 2004. Generally, more groups were found in the surface layer (0-10 m.) than the deeper one (10-20 m.). Some zooplankton groups undergo significant vertical migration at certain time of the year, others showed no clear differences in distribution patterns and exhibited no directed movement patterns. Some species stayed a part of the day within certain layer of the water column, others were randomly dispersed in the whole water column during different hours. Responses appear to depend also on the life stages of each zooplankton group, as well as other ecological conditions such as temperature, light and amount of food. Population budget indicates that the abundance of some groups was greater at the morning time, others at the sunset time. While the noon time often showed lower density. The time of the day which showed the lowest count of each group is known as the day deficit, which is probably due to diel horizontal migrations.
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| Format: | Journal Contribution biblioteca |
| Language: | English |
| Published: |
National Institute of Oceanograhy and Fisheries (NIOF)
2006
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| Subjects: | Hydrobiology, Zooplankton, Vertical migrations, Ecology, |
| Online Access: | http://hdl.handle.net/1834/1455 |
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| Summary: | Diel vertical migration of different zooplankton groups in Dekhaila Harbor was studied monthly from May 2003 to April 2004. Generally, more groups were found in the surface layer (0-10 m.) than the deeper one (10-20 m.). Some zooplankton groups undergo significant vertical migration at certain time of the year, others showed no clear differences in distribution patterns and exhibited no directed movement patterns. Some species stayed a part of the day within certain layer of the water column, others were randomly dispersed in the whole water column during different hours. Responses appear to depend also on the life stages of each zooplankton group, as well as other ecological conditions such as temperature, light and amount of food. Population budget indicates that the abundance of some groups was greater at the morning time, others at the sunset time. While the noon time often showed lower density. The time of the day which showed the lowest count of each group is known as the day deficit, which is probably due to diel horizontal migrations. |
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