The Doggerbank is the largest sandbank in the North Sea, covering an area of about 18 000 km2. It belongs to the EEZs of the United Kingdom, the Netherlands, Germany and Denmark. The German part of the Doggerbank only covers 1624 km2 and ranges from 29 to 40 m water depth (BfN, 2008b; Sell et al., 2011). Its habitat is classified as "sandbank with low permeant flooding by seawater" and divides two ecologically distinct southern and northern community types (Sell et al., 2011). It is an important habitat for endofauna adapted to substrate rearrangements, such as Bathyporaia-Fabulina communities (BfN, 2008b).
The Doggerbank is an important stepping stone for different fauna elements throughout the North Sea (Sell et al., 2011). It is an important foraging and reproduction ground for many fish species and therefore, an important foraging ground for seabirds and marine mammals such as harbour porpoises and seals. Additionally to these more frequent visitors, common minke whales, white-beaked and Atlantic white-sided dolphins have also been sighted at the Doggerbank (Sell et al., 2011).
The whole area gets disturbed by four fishing events per year (Sell et al., 2011). The biggest negative effect comes from the Sea Beam fishery that targets flat fish such as European plaice and common dap. The fisheries exclusion could result in the recovery of benthic communities which in turn would lead to an increase in prey for many fish species. In addition, a recovery in fish stocks would also have a positive effect on marine mammal populations.
Borkum Reef Ground
The Borkum Reef Ground lies in the south-west of the German EEZ. With 625 km2 it is a comparatively small but very diverse marine protected area. It is characterized by a large sandbank that covers around 80% of the area, with many dispersed reef areas (BfN, 2008c). The Borkum Reef Ground stretches from 18 m to 33 m depth and has a large substrate and habitat diversity and is populated by small-scale benthic communities such as the Fabulina fabula or the Goniadella-Spisula communities (BfN, 2008c; Sell et al., 2011).
The ecological relevance of this marine protected area is based on the high biodiversity supported by its habitat complexity.165 species have been identified in the macrozoobenthos, many of which are threatened species (www.bfn.de, „Das Schutzgebiet Borkum-Riffgrund“).
Sightings of harbour porpoises with calves have become more common. In additon, harbour and grey seals frequently use the Borkum Reef Ground as foraging area and pass through on their migratory routes (BfN, 2008c). Due to the many reefs distributed through out the Borkum Reef Ground, fishing pressure in the area is rather low, but a fishery exclusion will presumably have positive effects on this marine protected area, too.
Sylter outer reef - Eastern German bight
The Sylter outer reef covers an area of about 5314 km2 in the southern North Sea (BfN, 2008a; Sell et al., 2011). The marine protected area overlaps with another protected area the "Eastern German Bight", which falls under the birds directive, mainly due to the abundance of red and black-throated loons in this area (Sell et al., 2011). The Sylter outer reef is characterized by a high diversity of sediment and habitat structures. The western edge of the Sylter outer reef is the flank of the Elbe glacial valley. Coarse sand and gravel surfaces often protrude through the sand layer, as do individual stones and reefs. In the south-east one of the largest sandbanks in the German EEZ is located, the Amrumbank.
The two dominant habitat types at the Sylter outer reef are sandbanks and reef structures. The sandbank habitat is dominated by the Amrumbank. Here, typical sandbank communities inhabit the sediment, such as the Goniadella-Spisula community (BfN, 2008a). The Amrumbank also has an important interrelationship with the Macoma-balthica community from the Wadden Sea. This makes the Amrumbank communities unique in the German EEZ. The reef structures on the Sylt outer reef are characterized by large, contiguous moraine ridges and relic sediments (BfN, 2008; Sell et al., 2011). There are stone fields that protrude through the seabed in the central area of the Amrumbank and also contiguous, ribbon-like stone fields along the flanks of the Elbe glacial valley. Adding to the habitat complexity, scattered boulder fields are also characteristic for the seabed at the Sylter outer reef. Frequent sightings of harbour porpoises at the Sylter outer reef indicate the biggest resident population and highlight ts importance as a rearing and breeding ground, which has an enormous ecological relevance within the German EEZ (Sell et al., 2011).
The fishing pressure within the area of the Sylter outer reef varies. While the boulder fields and reef areas stay mostly untouched by fisheries, the eastern part is strongly influenced by fishing impacts. especially the Amrumbank is frequently being fished, where in some areas sensitive benthic communities have been strongly reduced (Sell et al., 2011). The fishery exclusion would therefore not only benefit fish populations, but could also lead to the recovery of benthic communities.
BfN. Erhaltungsziele für das FFH-Gebiet „Sylter Außenriff “ ( DE 1209-301 ) in der deutschen AWZ der Nordsee2008a:1–22.
BfN. Erhaltungsziele für das FFH-Gebiet „Doggerbank“(DE 1003-301) in der deutschen AWZ der Nordsee 2008b:1–11.
BfN. Erhaltungsziele für das FFH-Gebiet „Borkum-Riffgrund“ (DE 2104-301) in der deutschen AWZ der Nordsee 2008c:1–19.
Sell A, Pusch C, von Dorrien C, Krause J, Schulze T, Carstensen D. Maßnahmenvorschläge für das Fischereimanagement in Natura 2000-Gebieten der deutschen AWZ der Nord- und Ostsee. 2011