Joop W.P. Coolen

Marine Fouling Assemblages on Offshore Gas Platforms in the Southern North Sea: Effects of Depth and Distance from Shore on Biodiversity

Offshore platforms are known to act as artificial reefs, though there is on-going debate on whether this effect is beneficial or harmful for the life in the surrounding marine environment. Knowing what species exist on and around the offshore platforms and what environmental variables influence this species assemblage is crucial for a better understanding of the impact of offshore platforms on marine life. Information on this is limited for offshore platforms in the southern North Sea. This study aims to fill this gap in our knowledge and to determine how the composition and the abundance of species assemblages changes with depth and along a distance-from-shore gradient. The species assemblages on five offshore gas platforms in the southern North Sea have been inventoried using Remotely Operated Vehicles inspection footage. A total of 30 taxa were identified. A Generalised Additive Model of the species richness showed a significant non-linear relation with water depth (p = 0.001): from a low richness in shallow waters it increases with depth until 15–20 m, after which richness decreases again. Using PERMANOVA, water depth (p≤0.001), community age (p≤0.001) and the interaction between distance from shore and community age (p≤0.001) showed a significant effect on the species assemblages. Future research should focus on the effect additional environmental variables have on the species assemblages.

First record of Caryophyllia smithii in the central southern North Sea: artificial reefs affect range extensions of sessile benthic species

In the North Sea, observations of the solitary coral Caryophyllia smithii are mostly limited to the north-east coast of the United Kingdom including the Shetland and Orkney islands. To date, C. smithii has not been reported from far offshore locations in the North Sea south of 57.78N. Distribution of this species appears limited by the restricted availability of natural hard substrata in the central southern North Sea. There are, however, many artificial hard substrata in this area in the form of shipwrecks and offshore oil and gas installations. These may provide stepping stones for C. smithii to expand its distribution. Here we report the first sighting of C. smithii in the central southern North Sea on an unidentified wreck on the Dogger Bank. This is the first offshore observation of any hard coral in the central southern North Sea.

First record of Syllis vittata (Polychaeta: Syllidae) in the Dutch North Sea

BackgroundSyllis vittata is present from British Waters to the Mediterranean Sea, Morocco and the Canary Islands and recorded from the South African coast and Indian Ocean.Results and conclusionIn this paper, S. vittata is reported for the first time in the Dutch EEZ.

Records of five bryozoan species from offshore gas platforms rare for the Dutch North Sea

This study reports on bryozoan species collected at three offshore gas platforms in the Dutch part of the North Sea. Four out of thirteen observed species are considered as rare in the Netherlands, whereas Cribrilina punctata is a new species for Dutch waters.