ISSN:
1432-1793
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract In July 1988 a survey was made in the Dogger Bank area of the North Sea. As a result of wind stress the area was found to be frequently well mixed. At the northerly slope a transition zone was observed between the stratified central North Sea and the well-mixed Dogger Bank area. Low nutrient concentrations were observed in surface waters; especially for nitrate (〈0,1µM). High concentrations of phosphate (〉0,5µM), nitrate (〉1µM), ammonium (〉2µM) and silicate (〉2µM) only prevailed below the thermocline. Chlorophylla values were below 1µg l−1 near the surface. Enhanced values (up to 4µg l−1) were observed in the deeper layer at the transition zone and just below the thermocline at well-stratified locations. At the transition zone high specific C-fixation rates (up to 100 mg C mg−1 chla d−1) at the surface indicated the presence of enhanced productivity. The compensation depth for primary production was found to coincide with a specific C-fixation rate of 5 mg C mg−1 chla d−1. At greater depths, phytoplankton was only found where tidally induced vertical mixing allowed a regular exposure to higher light intensities. Storms resulted in a rapid redistribution of chlorophylla and enhancement of the C-fixation rate in the upper layer of the water column.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01344303
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