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| Girisch, H.B.; Dieleman, J.C.; Petersen, G.W.; Pinkster, S.. |
| 1. The migration of two sympatric estuarine species has been studied over a period of one year in the estuary of the river Dourduff, a small river draining into the Bay of Morlaix (Brittany, France). One species, Gammarus zaddachi, is a boreal species and the other, Gammarus chevreuxi, is a lusitanian species. Both species live near the limits of their distribution area. 2. Both species show a migration pattern with an anadromous and a catadromous phase. The migration is an active process. The animals use the tidal movements for their upstream and downstream migration. 3. Migration activities of both species show a diurnal rhythm, the activity peak occurring at night. 4. Downriver migration of both species can be observed throughout the whole year.... |
| Tipo: Article / Letter to the editor |
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| Ano: 1974 |
URL: http://www.repository.naturalis.nl/record/504507 |
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| Girisch, H.B.; Dennert, H.G.. |
| The migratory activity of Gammarus zaddachi and Gammarus chevreuxi is investigated in a current chamber, in which a tidal cycle can be simulated. In fresh running water the number of animals drifting with the current is of about the same magnitude as the number of animals actively swimming against the current. A diurnal periodicity is recorded in the migratory activity. The migratory activity is influenced by the population density and the food supply. In the current chamber a tidal cycle can be simulated by varying the factors current velocity, current direction, salinity, and temperature. The combination of a decrease in current velocity, followed by a slow current in the opposite direction, an increase in the salinity, and a rise in the temperature of... |
| Tipo: Article / Letter to the editor |
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| Ano: 1975 |
URL: http://www.repository.naturalis.nl/record/504600 |
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