Etude des migrations nycthémérales du zooplankton dans un milieu marin peu profond
Daro, M.H. (1974). Etude des migrations nycthémérales du zooplankton dans un milieu marin peu profond. Hydrobiologia 44(1-2): 149-160
In: Hydrobiologia. Springer: The Hague. ISSN 0018-8158; e-ISSN 1573-5117, more
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| Keywords |
Aquatic communities > Plankton > Zooplankton
Behaviour > Migrations
Biological phenomena > Biological rhythms > Nyctimeral rhythms
Water > Shallow water
ANE, Belgium, Oostende, Sluice Dock [Marine Regions]
Marine/Coastal; Brackish water |
| Abstract |
The Sluice-dock of Ostend, a shallow (1.5 m) marine biotope of 86 ha stays closed during some 6-7 months of the year and is not influenced by the tides. During 24 h cycles the nycthemeral migrations of the zooplankton at 5 depths in a watercolumn of 1 meter were studied in relation to several environmental factors: water temperature, dissolved oxygen, pH and chlorophyll content. The photosynthesis shows a minimum during the night and shows a maximum during the late afternoon, at which time the water-temperature is also maximal. Holo- and meroplanktonic organisms migrate towards the surface around 3-5 o'clock a.m., at which time the chlorophyll content is minimal, hence our hypothesis of nocturnal grazing, this phenomenon perhaps combined with a nocturnal division of phytoplankton cells. Each observed species has its own characteristic behaviour in relation to its negative diurnal phototropism and its own diurnal bottomward migration speed. |
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