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Ecological role of an offshore industry artificial structure

Ecological role of an offshore industry artificial structure
Ecological role of an offshore industry artificial structure
Decommissioning of oil and gas infrastructure globally has focused attention on its importance as hard substratum on continental shelf and slope habitats. Observational studies are needed to improve understanding of faunal assemblages supported by offshore infrastructure and better predict the effect of removal. Here, we present results from visual inspection and physical sampling of a small oil and gas industry structure decommissioned from an oil field in the North East Atlantic. This is supported by observations of similar structures nearby and by photographs of the surrounding seabed from environmental baseline surveys. The structure supported a reasonably high biomass and diversity of invertebrates (>10 kg and >39 macrofaunal and 17 megafaunal species) and fishes (>20 kg biomass and >4 species). The invertebrate megafaunal species present on the structure were a sub-set of the hard substratum fauna observed on surrounding seabed. Porifera were absent from the structure. Biological succession in the first 2 years occurred as follows. Sparse colonies of the hydroid Obelia sp. stet were early colonisers then subsequent development of thick hydroid turf (Obelia sp. stet. and Halecium sp. stet.) supported an invertebrate assemblage (2654 individuals kg wet mass–1) dominated by saddle oysters [Pododesmus squama (Gmelin, 1791) and Heteranomia sp. stet.)] and scale worms (Harmothoe spp.). Percentage cover of hydroid turf varied significantly over the structure, with most growth on sections exposed to strongest currents. Commercially important fish species present around the structure included Gadus morhua (Atlantic cod), Pollachius virens (saithe) and Lophius piscatorius (monkfish). Studies of artificial structures such as this provide much needed data to understand their role in the ecology of seafloor habitats and inform environmental decision making on all stages of industry from exploration to decommissioning. We show that the ecological role of the decommissioned three-dimensional structures was to enhance the biomass of a sub-set of epifaunal invertebrates found in the area. This supported diverse associated macrofaunal organisms, providing a food source for motile invertebrates and fishes in an area where background hard substratum can be lost through the impacts of drilling.
2296-7745
Gates, Andrew R.
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Horton, Tammy
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Serpell-Stevens, Amanda
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Chandler, Chester
c5e822b8-68eb-4803-a7a5-724e2923a19f
Grange, Laura J.
8de65684-8e14-4cc2-89d1-ca20322714e4
Robert, Katleen
49e4bfa2-0999-41ec-b50d-65c0f8896583
Bevan, Alexander
96653c99-6f66-4e96-ae24-44c897a74248
Jones, Daniel O. B.
44fc07b3-5fb7-4bf5-9cec-78c78022613a
Gates, Andrew R.
327a3cc6-2e53-4090-9f96-219461087be9
Horton, Tammy
c4b41665-f0bc-4f0f-a7af-b2b9afc02e34
Serpell-Stevens, Amanda
99c88c27-8478-479c-a1e2-eccfc36138f6
Chandler, Chester
c5e822b8-68eb-4803-a7a5-724e2923a19f
Grange, Laura J.
8de65684-8e14-4cc2-89d1-ca20322714e4
Robert, Katleen
49e4bfa2-0999-41ec-b50d-65c0f8896583
Bevan, Alexander
96653c99-6f66-4e96-ae24-44c897a74248
Jones, Daniel O. B.
44fc07b3-5fb7-4bf5-9cec-78c78022613a

Gates, Andrew R., Horton, Tammy, Serpell-Stevens, Amanda, Chandler, Chester, Grange, Laura J., Robert, Katleen, Bevan, Alexander and Jones, Daniel O. B. (2019) Ecological role of an offshore industry artificial structure. Frontiers in Marine Science, 6. (doi:10.3389/fmars.2019.00675).

Record type: Article

Abstract

Decommissioning of oil and gas infrastructure globally has focused attention on its importance as hard substratum on continental shelf and slope habitats. Observational studies are needed to improve understanding of faunal assemblages supported by offshore infrastructure and better predict the effect of removal. Here, we present results from visual inspection and physical sampling of a small oil and gas industry structure decommissioned from an oil field in the North East Atlantic. This is supported by observations of similar structures nearby and by photographs of the surrounding seabed from environmental baseline surveys. The structure supported a reasonably high biomass and diversity of invertebrates (>10 kg and >39 macrofaunal and 17 megafaunal species) and fishes (>20 kg biomass and >4 species). The invertebrate megafaunal species present on the structure were a sub-set of the hard substratum fauna observed on surrounding seabed. Porifera were absent from the structure. Biological succession in the first 2 years occurred as follows. Sparse colonies of the hydroid Obelia sp. stet were early colonisers then subsequent development of thick hydroid turf (Obelia sp. stet. and Halecium sp. stet.) supported an invertebrate assemblage (2654 individuals kg wet mass–1) dominated by saddle oysters [Pododesmus squama (Gmelin, 1791) and Heteranomia sp. stet.)] and scale worms (Harmothoe spp.). Percentage cover of hydroid turf varied significantly over the structure, with most growth on sections exposed to strongest currents. Commercially important fish species present around the structure included Gadus morhua (Atlantic cod), Pollachius virens (saithe) and Lophius piscatorius (monkfish). Studies of artificial structures such as this provide much needed data to understand their role in the ecology of seafloor habitats and inform environmental decision making on all stages of industry from exploration to decommissioning. We show that the ecological role of the decommissioned three-dimensional structures was to enhance the biomass of a sub-set of epifaunal invertebrates found in the area. This supported diverse associated macrofaunal organisms, providing a food source for motile invertebrates and fishes in an area where background hard substratum can be lost through the impacts of drilling.

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fmars-06-00675 - Version of Record
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Accepted/In Press date: 17 October 2019
Published date: 12 November 2019

Identifiers

Local EPrints ID: 435928
URI: http://eprints.soton.ac.uk/id/eprint/435928
ISSN: 2296-7745
PURE UUID: 467cacfc-4300-4f90-959b-f4db507ddcc5
ORCID for Laura J. Grange: ORCID iD orcid.org/0000-0001-9222-6848

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Date deposited: 25 Nov 2019 17:30
Last modified: 04 Dec 2019 01:31

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Contributors

Author: Andrew R. Gates
Author: Tammy Horton
Author: Amanda Serpell-Stevens
Author: Chester Chandler
Author: Laura J. Grange ORCID iD
Author: Katleen Robert
Author: Alexander Bevan
Author: Daniel O. B. Jones

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