We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
EXPERIMENTAL STUDIES ON THE ECOLOGY OF CERATIA.
- Authors
Nordli, Erling
- Abstract
1. The organisms used in the experiments were Ceratium tripos, C. fusus, C. furca and C. lineatum. 2. The methods for cultivation are described in detail, the more important points of which are: Ceratia must be handled more carefully than other dino-flagellates owing to the size and shape. They should not be subjected to temperature or salinity shocks during isolation and other transfers. 3. The growth rate in unicellular and multicellular cultures was investigated together with the effect of culture density upon growth rate. The division rate in cultures was found to lie within the ranges found in natural populations, and the Ceratium cultures behaved more or less like other cultures with exponential growth phases. 4. The optimal salinity for the Ceratium species in question was found to lie at 15-25‰ with a fairly large tolerance range. 5. The optimal temperature lay at 15-20°C, but the tolerance for lower temperatures varied considerably with the species. 6. The optimal light intensity was found to lie at approximately 5000 Lux for C. tripos and C. lineatum, and 2500 Lux for C. fusus and C. furca, intermediate values not investigated. Owing to the unchecked effects of phototaxis, the values given may be more or less erroneous. 7. Experiments with oceanic and neritic water for culture solutions revealed that ocean water is not satisfactory for preparation of Schreiber's solution. This medium, however, was considerably improved by an addition of soil extract. This was also true with neritic water. In aged water from the Oslofjord the addition of P + N did not improve the solution, indicating that this water contains enough of these elements for phytoplankton growth. 8. An investigation on the variation of the length of cells grown under different culture conditions showed that the average cell lengths of C. fusus, C. furca and C. lineatum were shorter in cultures than in natural populations, decreasing with increasing temperature and culture density. The cell lengths were also shorter in neritic than in oceanic water. 9. The variation of cell forms in clone cultures was demonstrated, with examples given indicating that abnormal nuclear fission is characteristic of aberrant cell forms. 10. An observation of bioluminescence in Ceratium fusus cultures was reported. 11. A comparison of temperature and salinity experiments and observations from Northern European coastal waters was undertaken. The results support the assumption that: 1) in the Baltic low salinity restricts the distribution of the Ceratium species in question; 2) the mass occurrence of ceratia in the Oslofjord in summer partly may be ascribed to the favourable temperature and salinity conditions in this locality; 3) the Norwegian coastal waters, Gran's "Tripos-region", is a biographical area which offers ceratia better growth conditions than the colder and saltier oceanic water to the west.
- Subjects
SALINITY; ECOLOGY education; PHOTOBIOLOGY; ENVIRONMENTAL sciences; POPULATION biology; NUCLEAR fission
- Publication
Oikos, 1957, Vol 8, Issue 2, p200
- ISSN
0030-1299
- Publication type
Article
- DOI
10.2307/3564999