scholarly journals Ecological implications of removing a concrete gas platform in the North Sea

2020 ◽  
Author(s):  
Joop W.P. Coolen ◽  
Oliver Bittner ◽  
Floor M.F. Driessen ◽  
Udo van Dongen ◽  
Midas S. Siahaya ◽  
...  
Keyword(s):  
North Sea ◽  
Local Community ◽  
Rocky Reef ◽  
Taxonomic Structure ◽  
Indigenous Species ◽  
Feeding Mode ◽  
Artificial Structures ◽  
The North ◽  
Species Invasions ◽  
The North Sea

ABSTRACTArtificial structures such as offshore oil and gas platforms can significantly alter local species communities. It has been argued that this effect should be considered during decisions over their removal during decommissioning. In the North Sea, leaving such structures in place is prohibited but derogations are allowed for large concrete installations. To assess removal options for one such installation, the Halfweg GBS (gravity-based structure) a concrete platform foundation off the Dutch coast, we studied the resident fouling macrofauna community. The faunal structure, biomass and trophic composition of the Halfweg was then compared with those from the surrounding seabed sediments, other local artificial structures and a natural rocky reef.In total, 65 macrofaunal species were observed on the concrete (52 species), steel legs (32) and surrounding rock dump (44) of Halfweg. Mean Simpson diversity per sample was highest on the rock dump (0.71) but concrete (0.54) and steel (0.60) of the GBS were lower than seabed (0.69). Ten of the species observed on the concrete were not reported on other substrates while 10 of the species were also observed in the surrounding seabed. The GBS structure was numerically dominated by Arthropoda which comprised 98% of the total abundance. Mean ash free dry weight (AFDW) was significantly higher (p<0.001) on the Halfweg substrates (204 g AFDW per m2) than in the surrounding seabed (65 g AFDW per m2). Over 94% of the biomass on Halfweg consisted of the plumose anemone Metridium senile. While common on other reefs, this species was absent from the surrounding seabed. Macrofaunal feeding mechanisms of the concrete and rock dump communities on the GBS were similar to those of nearby sediments, although these differed from those on the Halfweg steel legs. Therefore, the presence of Halfweg alters the local community feeding modes. Multivariate analysis revealed that taxonomic structure of the GBS and other artificial structures significantly differed from that of the sedimentary habitats. Low numbers of non-indigenous species on Halfweg indicated that the structure does not act as a stepping stone for species invasions.Our data show that the Halfweg structures significantly increase local biodiversity and biomass. Removal of the concrete and steel legs of the GBS (leaving the rock dump) will significantly reduce local macrofauna biodiversity. The long-term impact on macrofaunal biomass is low. Leaving the complete Halfweg structure in place will result in an enriched local macrofaunal biodiversity and feeding mode diversity.

Structure in a sea of sand: fish abundance in relation to man-made structures in the North Sea

2018 ◽  
Vol 77 (3) ◽  
pp. 1206-1218 ◽  
Author(s):  
Serena R Wright ◽  
Christopher P Lynam ◽  
David A Righton ◽  
Julian Metcalfe ◽  
Ewan Hunter ◽  
...  
Keyword(s):  
North Sea ◽  
Gadus Morhua ◽  
Oil And Gas ◽  
Generalized Additive Models ◽  
Strong Association ◽  
Additive Models ◽  
Artificial Structures ◽  
Habitat Alterations ◽  
The North ◽  
The North Sea

Abstract Artificial structures in the marine environment may have direct and/or indirect impact on the behaviour and space use of mobile foragers. This study explores whether environmental and physical features in the North Sea—including artificial structures (wrecks, wind turbines, cables, and oil and gas structures) were associated with local abundance of three fish species: cod (Gadus morhua), plaice (Pleuronectes platessa), and thornback ray (Raja clavata). Generalized additive models (GAMs) were used to compare distributions between data collected by fisheries surveys and electronic tags. Distributions of cod, plaice, and ray were correlated with environmental variables including temperature, depth, and substrate, matching findings from previous studies. All species showed seasonal increases in their abundance in areas with high densities of artificial structures, including oil and gas platforms and wrecks. Independent of whether fish purposefully associate with these features or whether structures happen to coincide with locations frequented by these populations, the strong association suggests that greater consideration needs to be given to regulation of habitat alterations, including decommissioning.

scholarly journals A reliable DNA barcode reference library for the identification of benthic invertebrates: essential for biomonitoring of the North Sea

2021 ◽  
Vol 4 ◽  
Author(s):  
Magdalini Christodoulou ◽  
Berry van der Hoorn ◽  
Laure Van den Bulcke ◽  
Sofie Derycke ◽  
Annelies De Backer ◽  
...  
Keyword(s):  
North Sea ◽  
High Throughput Sequencing ◽  
Dna Barcode ◽  
Morphological Identification ◽  
Indigenous Species ◽  
Reference Library ◽  
The North ◽  
Sampling Campaign ◽  
The North Sea ◽  
Cost Efficient

Benthic macroinvertebrates are key components in environmental impact assessments. Nevertheless, their use as bioindicators can be constrained by the time- and cost-consuming processes needed for their morphological identification. The recent advances in high-throughput sequencing, particularly DNA metabarcoding can provide an alternative to morphology-based approaches. The main limitation for DNA-based tools to be implemented in biomonitoring projects is the considerable investment needed to build high-quality and curated taxonomic reference DNA sequence libraries for species identification. To begin addressing this shortage, Interreg NSR project GEANS aim in developing a curated DNA reference library based on mitochondrial cytochrome c oxidase subunit I (COI) for the North Sea macrobenthos that will serve as the backbone of all the molecular protocols. For the collection of the macroinvertebrates, a targeted sampling campaign is underway across the North Sea Region, while existing collections are being scanned. Macrobenthic specimens are being processed following a series of standardised work flows covering sampling, morphological identifications, molecular lab processing and data handling. GEANS' reference library, currently holds DNA barcodes for 3443 specimens collected from various areas of the North Sea. In total 11 phyla, 28 classes, 80 orders, 280 families, 428 genera and 586 species (37 non-indigenous species) are represented within the library. Species-level identification is taxonomically verified for over 90 % of the species, while genus-level identifications are verified for almost 100 % of the genera. GEANS reference library covers so far over 30 % of North Sea species and its constantly enriched. All specimens are photographed and together with the accompanying sequences, collection and taxonomic data are archived in a dedicate BOLD project. Voucher specimens and DNA extracts are archived at three different institutes in Germany (Senckenberg am Meer), the Netherlands (Naturalis) and Belgium (ILVO). Once available, this DNA-library will be based on taxonomically well-curated specimens and it will support the implementation of fast, cost-efficient and reliable DNA-based identifications and subsequently environmental health assessments in the North Sea.

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