Marine Communities of North Sea Offshore Platforms, and the Use of Stable Isotopes to Explore Artificial Reef Food Webs

Stable isotope methods offer a powerful means of investigating trophic<br/>interactions, allowing assessment of the relative importance of multiple nutrient<br/>sources to biological assemblages, as well as estimation of the trophic positions of<br/>consumers. Differences in the isotope ratios of consumers between habitats can<br/>thus indicate differences in the structures of food webs, or the contributions of<br/>different food sources to those food webs.<br/>Isotope methods were used to compare the food web of an artificial reef located<br/>off the south coast of England with that of a nearby natural reef system, revealing a<br/>similarly complex food web, with similar trophic structure, and similar inputs from<br/>the available food sources. Isotope methods should be incorporated into more<br/>artificial reef studies, where they have been seldom applied.<br/>Offshore oil and gas platforms in the North Sea are artificial reefs, hosting<br/>substantial assemblages of sessile invertebrates and other associated fauna, and<br/>attracting large numbers of fish and motile invertebrates. Structural survey footage<br/>provided by the oil and gas industry allowed the investigation of the marine life<br/>associated with several of these structures, of varied ages and in various locations<br/>in the North Sea.<br/>At least thirty?six taxa of motile invertebrates and fish were observed in association<br/>with the structures, most of which were present on all platforms surveyed. While<br/>most reef?associated fish were observed around the base of the larger platforms,<br/>many thousands of fish were also observed in the water column around these<br/>structures at other depths. A small number of sessile taxa dominated the fouling<br/>assemblages, in places achieving total coverage of the available surfaces. Fouling<br/>composition changed with depth, but this pattern was not identical on all<br/>platforms. Platform age and location both affected the fouling assemblages<br/>present, but these two factors did not fully explain all the variation.

Name dc:type.qualificationname

Ph.D.

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of Southampton

Year dc:date.issued

2009

Author dc:creator

• Guerin, Andrew James