Search

As agencies shift from single-species management to ecosystem-based fisheries management, ecosystem models are gaining interest for understanding species dynamics in relation to oceanographic and ecological processes and human marine uses. However, information on community structure or distribution of many species that occupy deep (>30 m) waters is largely unavailable. We amassed a total of 24 686 fish observations of 523 species/taxa for the 30−410 m depth areas surrounding the main Hawaiian Islands (MHI). We also obtained estimates of geomorphological variables, including substrate type, slope, rugosity, and ridge-like features. Using these 2 data sources, we (1) identified distinct fish communities along the 30−410 m depth gradient, and (2) generated relative biomass maps for fish functional groups. We showed that the mesophotic zone ranges between 30 and 129 m, with a fish faunal break at 60 m. Beyond this zone, 4 subphotic zones were identified: upper rariphotic (130−169 m), mid-rariphotic (170−239 m), lower rariphotic (240−319 m), and upper bathyal (320−410 m). We assigned fish species to functional groups partly based on identified depth ranges and fitted general additive models (GAMs) integrating geomorphological covariates to the functional group relative biomass estimates to determine the environmental variables that best predict the probability of encounter and relative biomass of each fish functional group. Finally, GAM predictions were employed to map functional group relative biomass distributions. These distribution maps showed a high relative biomass of many groups in the center of the MHI chain. This study contributes to a better understanding of fish community structure around the MHI and will inform ecosystem model parameterization.

An integrated geophysical, geological, and geochemical investigation of seabed fluid venting was carried out in upper Bantry Bay, a large marine inlet on the southwest coast of Ireland. The results provide evidence of the seafloor venting of gas rich fluids, resulting in the formation of a pockmark field identified here for the first time. The pockmarks occur in an area where sub-bottom profiles provide evidence of chimney-like features interpreted to record upward gas migration through Quaternary sediments to the seafloor. Three vibrocores up to 6 m long were acquired in water depths of 24–34 m, two from the pockmark field and one from outside. Methane of predominantly biogenic origin was quantified in all three cores by headspace analysis of sediment sub-samples. Well-defined sulfate methane transition zones (SMTZs) were observed in two of the cores, the shallowest (1.25 m below sea floor (mbsf)) inside the pockmark field and the other (3.75 mbsf) outside. It is likely that an SMTZ occurs at the location of the third core, also within the pockmark field, although deeper than the samples obtained during this study. Gas migration towards the seafloor is suggested to involve both diffuse pore fluid migration across wide areas and focused flow through the pockmarks, together driven by methanogenesis of pre-glacial lacustrine sediments preserved in a bedrock basin, and possible gas release from the Owenberg River Fault. Analysis of phospholipid fatty acids (PLFAs) and archaeal isoprenoid hydrocarbons was used to investigate the microbial ecology of these sediments. Anaerobic oxidation of methane (AOM) may play a role in controlling release of CH4 to the water column and atmosphere in this shallow gas setting, potentially mediated by syntrophic sulfate reducing bacteria (SRB) and anaerobic methanotrophic archaea (ANME).

High-resolution bathymetric data have been central to recent advances in the understanding of past dynamics of the former British–Irish Ice Sheet (BIIS). As approximately two-thirds of the former BIIS was probably marine-based during the Last Glacial Maximum (LGM) (c. 29–23 ka), geomorphic observations of the seabed are required increasingly to understand the extent, pattern and timing of past glaciation. Until recently, glacial reconstructions for the Inner Hebrides, offshore of western Scotland, have been based primarily on terrestrial observations. Previous workers have proposed generalized reconstructions in which the Inner Hebrides are located within a significant former ice-sheet flow pathway that drained the western Scottish sector of the BIIS, feeding the Barra Fan during the LGM and earlier glaciations (Fig. 1). Results from numerical ice-sheet modelling suggest that former ice-flow velocities within the region were on the order of hundreds to thousands of metres per year, but yield further insight by demonstrating how dynamic binge/purge cycles may have affected ice-sheet mass balance over time (Hubbard et al. 2009). Following the LGM, ice-sheet retreat through the area is estimated to have been in the order of 20 m per year (Clark et al. 2012). Here we present swath-bathymetric data from the Inner Hebrides that provide in situ constraints on ice-sheet flow and subsequent retreat dynamics from within this important sector of the BIIS.

The BGS has developed a two- part classification system (‘Morphology’ and ‘Geomorphology’) to facilitate work on a new ‘S eabed Geomorphology’ mapping initia tive, and this classification system is the focus of this report. As stated in the Foreword, the rationale and the basic framework of the classification system were conceived and es tablished within BGS, but recent collaboration within the MAREANO -Norway, INFOMAR -Ireland, and MAREMAP -UK (MIM) partnership has led to significant improvement of the classifi cation system, and this report. To further support this effort, existing BGS GIS tools (SIGMA) ha ve been adapted to apply this two-part classification system for more efficient geom orphological mapping in the marine environment. This report:  provides a brief background on seabed mapping and characterisation, as well as how this science has been addressed historically within BGS;  describes the current motiva tion to conduct seabed geom orphological mapping, and the requirement for a new set of t ools to facilitate this work;  describes the logical framework that underpins the classification system;  outlines the attributes of the classification system, how it can be applied, and discusses the advantages and limitations of the approach. It is anticipated that through testing and usage, the classification syst em will be revised and improved over time, with updated versions released through MIM partnershi p. It is also planned that a further ‘user guide’ report will be produced for the classifi cation system and the GIS tools, including thematic details (e.g. background information on ‘coastal’ or ‘glacial’ features) and a feature glossary.

We briefly describe three methods of seabed characterization which are ‘fit for purpose’, in that each approach is well suited to distinct objectives e.g. characterizing glacial geomorphology and shallow glacial geology vs. rapid prediction of seabed sediment distribution via geostatistics. The methods vary from manual ‘expert’ interpretation to increasingly automated and mathematically based models, each with their own attributes and limitations. We would note however that increasing automation and mathematical sophistication does not necessarily equate to improve map outputs, or reduce the time required to produce them. Judgements must be made to select methodologies which are most appropriate to the variables mapped, and according to the extent and presentation scale of final maps.

The Dogger Bank zone is the largest of the Round 3 offshore wind zones extending over ~8660km2. It is located between 125km and 290km northeast of Yorkshire on the Dogger Bank, a topographic high point in the middle of the North Sea, with water depths of 18–63m. The sheer size of this zone is considerably greater than that of standard shallow-water oil and gas site investigations, leading to the generation of extremely large data volumes to manage, interpret and move between partners. This paper outlines the methodologies that Forewind, a consortium of energy companies, is utilising to prepare for the zone's development. This includes activities undertaken to date to develop a 3D model of the geology, stratigraphy and geotechnical conditions to assist in optimal selection of wind turbine foundations, both location and type. Survey programmes and preliminary results also are presented and discussed, illustrating experiences with ultra-high resolution multichannel sparker, shallow gas, glacial tectonics and fractured clays.

The Humber Regional Environmental Characterisation (REC) is a multidisciplinary marine study of the geology, biology and archaeology of an area of 11 000 km2 off the east coast of England. It was funded by the Marine Aggregate Levy Sustainability Fund (MALSF). 2. Within the REC area, there are 12 active aggregate licences with applications submitted for 10 more. Within the region there is also gas production, wind energy development, and intensive shellfish harvesting. Without proper management of the sea bed areas there could be conflict over development of resources in the area. 3. The overall objective of the REC project was to provide integrated broadscale seabed maps in order to support the sustainable management of offshore resources now and into the future. The basis of the maps is a regional assessment of the physical, biological and archaeological environment. Here for the Humber REC area we present the results of each individual project element together with their integration into a holistic overview of the marine environment. 4. In addition to SeaZone single beam bathymetry, data from three geophysical and one sampling survey provided the basis for the interpretation. BGS legacy data supplemented the new data set. In total these data provided a sound basis for reporting on the regional character of the geology, biology and archaeology of the area. 5. The geology of the Humber REC area is characterised by a western gravelly region, a sandy eastern one and a transitional area in between. Outside of large sand banks and areas of sand waves the mobile sediment cover is thin. The terminations of the outer Norfolk Banks are located in the southeast of the area, and a series of low amplitude sinuous and linear banks are found in the southwest and centre. A number of arcuate and linear deeps, with a radial pattern incise the seabed. 6. The morphology and sediment distribution are attributed to a number of episodes; initially the region was glaciated and the Bolde