|Seabirds recorded in the northern North Sea in July: the ecological implications of their distribution|
Joiris, C. (1977). Seabirds recorded in the northern North Sea in July: the ecological implications of their distribution, in: Elskens, I. et al. (Ed.) Studie en Beheer van het Mariene Systeem: 4de Colloquium E4-77, Louvain-la-Neuve, 18 juli-5 augustus 1977, vol. 1. pp. 195-217
In: Elskens, I.; Sanfeld, A.; Vigneron, J. (Ed.) (1977). Studie en Beheer van het Mariene Systeem: 4de Colloquium E4-77, Louvain-la-Neuve, 18 juli-5 augustus 1977, vol. 1. Vrije Universiteit Brussel: Brussel. 393 pp., more
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VLIZ: Proceedings 
|Document type: Conference paper|
The distribution of seabirds in the northern North Sea in July 1975 clearly shows a 2 zone pattern. In the northwest, zone 1 englobes the great majority of offshore seabirds ( Alcids, Skuas and Gannet), is characterized by high numbers of Fulmars and corresponds with Atlantic water intruding into the North Sea. Zone 2 is characterized by lower numbers of birds, including less fulmars and corresponds with typical North Sea water. Important groups of moulting sub-adult Kittywake are accumulating in subzone 2a, close to the limit of zone 1. This distribution of seabirds probably reflects the abundance of their food, mainly zooplankton and small fish. Because the primary production is of the same order of magnitude in the 2 zones, it is suggested that the main difference lies in the structure of the food web, the northern zone 1 being characterized by a complete food chain: phytoplankton, zooplankton, fish, birds. In zone 2, on the contrary, the phytoplanktonic organic matter is recycled through the by-pass of the heterotrophic bacteria and the higher steps are partially suppressed. The first available results on other parameters (nutrients, bacteria, zooplankton) can fit within this scheme.