Sand waves are well known indicators of a mobile seabed. What do we expect of these features in terms of migration rates and seabed scour? We discuss these effects on seabed structures, both for the Oil and Gas and the Windfarm Industries, and consider how these impact on turbines and buried cables. Two case studies are presented. The first concerns a windfarm with a five-year gap between the planning survey and a subsequent cable route and environmental assessment survey. This revealed large-scale movements of sand waves, with the displacement of an isolated feature of 155 m in five years. Secondly, another windfarm development involved a re-survey, again over a five-year period, but after the turbines had been installed. This showed movements of sand waves of ∼50 m in five years. Observations of the scour effects on the turbines are discussed. Both sites revealed the presence of barchans. Whilst these have been extensively studied on land, there are few examples of how they behave in the marine environment. The two case studies presented show that mass transport is potentially much greater than expected and that this has implications for choosing turbine locations, the effect of scour, and the impact these sediment movements are likely to have on power cables.

Predictive modelling of deep-sea species and assemblages with multibeam acoustic datasets as input variables is now a key tool in the provision of maps upon which spatial planning and management of the marine environment can be based. However, with a multitude of methods available, advice is needed on the best methods for the task at hand. In this study, we predictively modelled the distribution and extent of three vulnerable marine ecosystems (VMEs) at the assemblage level (‘Lophelia pertusa reef frameworks’; ‘Stylasterids and lobose sponges’; and ‘Xenophyophore fields’) on the eastern flank of Rockall Bank, using three modelling methods: MaxEnt; RandomForests classification with multiple assemblages (gRF); and RandomForests classification with the presence/absence of a single VME (saRF). Performance metrics indicated that MaxEnt performed the best, but all models were considered valid. All three methods broadly agreed with regard to broad patterns in distribution. However, predicted extent presented a variation of up to 35 % between the different methods, and clear differences in predicted distribution were observed. We conclude that the choice of method is likely to influence the results of predicted maps, potentially impacting political decisions about deep-sea VME conservation.

Recent advances in marine acoustic survey and land-based topographic monitoring technologies have resulted in increasingly cost-effective data acquisition in coastal areas. The DEFRA-funded National Network of Regional Coastal Monitoring Programmes of England are, for example, utilising swath bathymetry and airborne light detection and ranging (LiDAR) technology more routinely to survey the coastal zone around the coastline of England. The demand for data processing, visualisation and interpretation techniques to keep pace with such advances in data acquisition is clear. This study discusses collection and processing techniques for such data on the south coast of Dorset, England, which have enabled the production of a seamless, high spatial resolution digital elevation model across the coastal zone. Case studies demonstrate how this elevation model can be viewed and analysed using state-of-the-art digital techniques to allow geological mapping to be extended from onshore to offshore in unprecedented detail, effectively eliminating what is known as the ‘White Ribbon’ for coastal geological mapping. The potential for rolling out such techniques for wider surveying programmes across many environmental disciplines is significant, which could contribute towards improving the multi-disciplinary scientific evidence base in the complex coastal zone.

This paper presents recently collected swath bathymetry from the Firth of Lorn. 553 km2 of data were collected during 2012–2013 as part of the INIS Hydro (Ireland, Northern Ireland and Scotland Hydrographic Survey) programme.

The area proves to consist of bedrock-dominated seabed, divided into narrow, stratigraphically-constrained and glacially-over-deepened basins. The bedrock is composed of late Proterozoic Dalradian metasediments overlain unconformably by Old Red Sandstone (ORS) sediments and lavas of ?Silurian-age. The central region of the Firth of Lorn is dominated by a vertical cliff, up to 150 m high and extending for approximately 24 km. This feature, here termed the Insh Fault, may have originated as a Dalradian extensional fault, been reactivated as an ORS feature and now forms a fault-line scarp with resistant ORS rocks on the downthrown side, flanking the more deeply eroded metasediments exposed in the basin. Tertiary intrusives are common, in particular, swarms of Paleocene dolerite dykes exposed on the sediment-free bedrock surfaces, and can be traced for many kilometres.

Evidence for past glaciation is widespread, manifest in the extensive erosion of the bedrock platforms and the abundance of well-preserved moraines and over-deepened basins. The survey region includes the Corryvreckan Whirlpool and Great Race, beneath the tidal flows of which occur submarine dunes.

Fifty six sediment cores were collected along a 100 km longitudinal transect of the Thames estuary. Total Hg ranged from 0.01 to 12.07 mg/kg, with a mean of 2.10 mg/kg (n=351). Concentrations of the toxic metal decreased downstream from London to the outer estuary and were positively correlated to total organic carbon (TOC) content. Many Hg profiles showed a clear rise, peak and fall, reflecting changing anthropogenic input through time. Surface concentrations averaged 1.27 mg/kg, confirming the effectiveness of recent environmental legislation and improved river management. Sediments at >40 cm depth from London reaches of the river (Waterloo Bridge, Cuckolds Point (Rotherhithe), Butlers Wharf (Tower Bridge), Millwall, Deptford and Millennium Dome) were highly contaminated, with levels of Hg of >7 mg/kg. The outer Thames had lower Hg, with the exception of Rainham, Crossness and Cliffe. Benchmarking against UK guidelines for the disposal of dredged material revealed that 88 samples from 21 sites exceeded the 3 mg/kg criteria (unsuitable for disposal at sea); 173 fell between 0.3 and 3 mg/kg (further assessment required); and 90 were of no concern. Using Hg as a generic pollution marker, the tidal Thames is one of the world's most contaminated river–estuarine sediment systems.

This study uses marine geophysical data, principally single-beam and high-resolution multibeam echo sounder bathymetry, combined with seismic sub-bottom profiles, and existing Quaternary geological information, to map the glacial geomorphology of a large area of seafloor (∼50,000 km2) on the continental shelf around northern Scotland, from west of Lewis to north of the Orkney Islands. Our new mapping reveals the detailed pattern of submarine glacial landforms, predominantly moraines, relating to ice sheets that covered Scotland and much of the continental shelf during the Late Weichselian glaciation and earlier in the Mid to Late Pleistocene. The reconstructed retreat pattern based on geomorphological evidence highlights the large number of different retreat stages and the asymmetric, non-uniform evolution of this ice sheet sector during Late Weichselian deglaciation. Time-equivalent ice-front reconstructions show that marine sectors of the ice sheet, such as the Minch, changed their geometry significantly, perhaps rapidly; whilst other sectors remained relatively unchanged and stable. We suggest that this behaviour, governed principally by bed topography/bathymetry and ice dynamics, led to reorganisation of the Late Weichselian ice sheet as it retreated back to two main ice centres: one in Western Scotland and the other over Orkney and Shetland. This retreat pattern suggests relatively early deglaciation of NW Lewis (ca. 25 ka BP) and the mountains of far NW Scotland – the latter possibly forming a substantial ice-free land corridor. Our reconstructions differ from most previous syntheses, but are strongly supported by the independently-mapped offshore Quaternary succession and key onshore dating constraints.