Marine fouling

1992 ◽  
Vol 100 ◽  
pp. 169-184 ◽  
Author(s):  
David Sell
Keyword(s):  
North Sea ◽  
Offshore Structures ◽  
Fouling Communities ◽  
Geographical Differences ◽  
The North ◽  
The North Sea ◽  
Fouling Organisms ◽  
Fouling Assemblages

SynopsisA comparison of macrofouling assemblages on offshore structures in the North Sea has revealed some similarity in their general characteristics, with a predominance in climax communities of relatively few species, such as the plumose anemone Metridium senile (L.) and the soft coral Alcyonium digitatum L., covering large proportions of the substratum. Specific geographical differences in community composition, diversity and successional development have been identified, however, and these are discussed in relation to environmental conditions and larval dispersal. In practical terms, the conservation of offshore fouling communities depends upon the fates of structures supporting these assemblages. Since the U.K.'s approach to platform decommissioning could ultimately involve the in situ toppling of structures in sea depths greater than 100 m, there would appear to be little threat to the long-term existence of offshore habitats for deep-water fouling assemblages. Moreover, an abundance of largely uninvestigated habitats for fouling organisms exists on submerged wrecks and other man-made structures. Thus, there appears to be no basis for a conservation requirement in relation to the fouling communities on fixed structures in the North Sea.

Long-term dynamics of fouling communities found on offshore installations in the North Sea

2003 ◽  
Vol 83 (5) ◽  
pp. 897-901 ◽  
Author(s):  
P. Whomersley ◽  
G.B. Picken
Keyword(s):  
North Sea ◽  
Offshore Platforms ◽  
Fouling Communities ◽  
The North ◽  
Offshore Installations ◽  
Oil Export ◽  
The North Sea ◽  
Northern North Sea ◽  
Fouling Organisms

Inspection videos of four offshore platforms in the central and northern North Sea were used to study the development of fouling communities on clamps and guides of oil export risers over an 11-y period (1989–2000). Results from multivariate analyses (multi-dimensional scaling and analysis of similarities) indicated that distinct assemblages developed in different geographical locations. These differences were mainly due to the protracted development of theMetridium senile(Cnidaria: Actinaria) zone on the northern sector platforms. The vertical zonation of fouling organisms was similar on all installations, although the water depth at platform locations varied from 80 to 169 m, indicating that fouling organisms display a wide bathymetric tolerance. This study has highlighted the value of long-term data present in operational inspection videos for the study of fouling communities.

Development of Fatigue Design Standards for Marine Structures

2017 ◽  
Author(s):  
Inge Lotsberg
Keyword(s):  
North Sea ◽  
Wind Turbines ◽  
Offshore Structures ◽  
Support Structures ◽  
Marine Structures ◽  
Design Standards ◽  
The North ◽  
Fatigue Design ◽  
The North Sea

Fatigue design standards for offshore structures became needed with development of offshore structures in harsh environments like the North Sea during the 1970s. The Ultimate Limit State had earlier been the most significant design requirement for similar platforms in the Mexican Gulf being less utilized with respect fatigue. The need for fatigue design of ship structures became increased as more high strength steel was being used in these structures during the 1970s. The analysis method for long term loading and assessment of fatigue capacity has been improved over the years and this has also resulted in need for new and revised design standards. New types of structures and structural components have been developed like tension leg platforms and support structures for wind turbines. These structures are subjected to significant dynamic loading such that fatigue design becomes the main issue and relevant fatigue design standards are needed. Fatigue assessment of fixed offshore structures in the North Sea has been standard practice since the 1970s. Fatigue of floating platforms became a requirement after the accident with the Alexander Kielland platform in 1980. Later new types of structures have been installed in the North Sea such as tension leg platforms and floating production ships where fatigue has been an important part of the design. A further challenge with respect to fatigue came with the development of support structures for wind turbines to be installed in the sea. This paper gives an overview of the development of fatigue design standards for marine structures over the last 40 years. This includes the significance of refined calculation of long term stress range distribution, calculation of hot spot stress, size effect and effect of mean stress effect on fatigue design of ship structures.

Pipeline Decommissioning: Comparative Study of Pipeline Corrosion in the North Sea and the Gulf of Thailand

2021 ◽  
Author(s):  
Jose Campins Bravo
Keyword(s):  
Carbon Steel ◽  
Corrosion Rate ◽  
North Sea ◽  
Marine Environment ◽  
Gulf Of Thailand ◽  
The North ◽  
The North Sea ◽  
The Gulf Of Thailand

Abstract The long-term degradation of decommissioned pipelines left in situ is an important topic in decommissioning projects. These constitute a long-term health and safety challenge in the form of snagging risk to other users of the sea. An accurate forecast of the long-term behavior of the pipelines in the marine environment would allow to make an informed decision regarding the feasibility of leave in place option for pipeline decommissioning. This paper aims to summarize the effect that individual environmental factors in marine corrosion have on the corrosion rate and to discuss in detail a chosen corrosion model that could be used to predict the long-term corrosion of in situ decommissioned subsea carbon steel pipelines in the marine environment. In addition, the long-term degradation will be predicted with the chosen corrosion model and the results will be compared for a range of subsea pipelines to be decommissioned in the North Sea and the Gulf of Thailand. With the chosen corrosion loss model, considering the higher average annual seabed temperature in the Gulf of Thailand in comparison with the North Sea, the predicted long-term corrosion rate of unprotected carbon steel is 0.053 mm/y for the North Sea and 0.069 mm/y for the Gulf of Thailand.

scholarly journals Long-term series in ichthyoplankton: sole and sprat at French coast of the North Sea from 1975 to 1994

1998 ◽  
Vol 21 (1) ◽  
pp. 113-121 ◽  
Author(s):  
Daniel Woehrling ◽  
Geneviève Le Fèvre-Lehoërff
Keyword(s):  
North Sea ◽  
The North ◽  
The North Sea

scholarly journals Observing and modelling phytoplankton community structure in the North Sea

2017 ◽  
Vol 14 (6) ◽  
pp. 1419-1444 ◽  
Author(s):  
David A. Ford ◽  
Johan van der Molen ◽  
Kieran Hyder ◽  
John Bacon ◽  
Rosa Barciela ◽  
...  
Keyword(s):  
Community Structure ◽  
North Sea ◽  
Phytoplankton Community ◽  
Marine Biodiversity ◽  
Phytoplankton Community Structure ◽  
Pigment Analysis ◽  
The North ◽  
The North Sea ◽  
In Situ Observations

Abstract. Phytoplankton form the base of the marine food chain, and knowledge of phytoplankton community structure is fundamental when assessing marine biodiversity. Policy makers and other users require information on marine biodiversity and other aspects of the marine environment for the North Sea, a highly productive European shelf sea. This information must come from a combination of observations and models, but currently the coastal ocean is greatly under-sampled for phytoplankton data, and outputs of phytoplankton community structure from models are therefore not yet frequently validated. This study presents a novel set of in situ observations of phytoplankton community structure for the North Sea using accessory pigment analysis. The observations allow a good understanding of the patterns of surface phytoplankton biomass and community structure in the North Sea for the observed months of August 2010 and 2011. Two physical–biogeochemical ocean models, the biogeochemical components of which are different variants of the widely used European Regional Seas Ecosystem Model (ERSEM), were then validated against these and other observations. Both models were a good match for sea surface temperature observations, and a reasonable match for remotely sensed ocean colour observations. However, the two models displayed very different phytoplankton community structures, with one better matching the in situ observations than the other. Nonetheless, both models shared some similarities with the observations in terms of spatial features and inter-annual variability. An initial comparison of the formulations and parameterizations of the two models suggests that diversity between the parameter settings of model phytoplankton functional types, along with formulations which promote a greater sensitivity to changes in light and nutrients, is key to capturing the observed phytoplankton community structure. These findings will help inform future model development, which should be coupled with detailed validation studies, in order to help facilitate the wider application of marine biogeochemical modelling to user and policy needs.

scholarly journals The ‘Yellow Danger’? Global forces and global fears in the North Sea and beyond (1600–1950)

2015 ◽  
Vol 27 (4) ◽  
pp. 743-754
Author(s):  
Matthias van Rossum
Keyword(s):  
Labour Market ◽  
North Sea ◽  
Labour Markets ◽  
Labour Relations ◽  
The North ◽  
15Th Century ◽  
Global Connections ◽  
The North Sea

Since direct shipping routes between Europe and Asia opened up at the end of the 15th century, the growing intercontinental and regional shipping connections resulted in increasing entanglements between European and Asian maritime labour markets. This article analyses the long term development of the connections between European and Asian maritime labour markets and its impact on socio-cultural (and labour) relations through three elements: first, the changing connections between European and Asian maritime labour markets; second, the changing nature of European and Asian maritime labour markets and its influence on the positions of sailors; and third, the changing relations between European and Asian sailors and its effects on the reactions and interactions in a globalising maritime labour market. It explores how these changing global connections shaped encounters between European and Asian sailors on (intercontinental) shipping in and from the North Sea region, and how it affected the positions and reactions of its workers.

scholarly journals Connectivity of larval stages of sedentary marine communities between hard substrates and offshore structures in the North Sea

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Johan van der Molen ◽  
Luz María García-García ◽  
Paul Whomersley ◽  
Alexander Callaway ◽  
Paulette E. Posen ◽  
...  
Keyword(s):  
North Sea ◽  
Offshore Structures ◽  
Marine Communities ◽  
Larval Stages ◽  
The North ◽  
The North Sea ◽  
Hard Substrates
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