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Vicky West

+44 (0)23 8071 1851

Measuring dredging impact on black bream

Tarmac Marine, CEMEX UK, Hanson Marine

Ecological Survey
Hydrographic-Geophysical Survey

Any aggregate producers operating in the locality of Kingmere Marine Conservation Zone (MCZ) are required to monitor black bream nest viability and densities to ensure dredging causes no significant negative impacts.

Tarmac Marine and CEMEX UK Marine commissioned ABPmer to undertake an assessment of black bream (Spondyliosoma cantharus) nesting activity in survey areas within, and in the vicinity of, the Kingmere MCZ, to contribute to annual monitoring requirements for Areas 453 and 488 licences.

A geophysical survey was undertaken to record the multibeam backscatter data, providing an interpretation of the location and density of the bream nests.

ABPmer’s surveyors used a survey vessel mobilised with a high-resolution Kongsberg 2040C multibeam echosounder interfaced with an Applanix PosMV inertial positioning system. Multibeam data was acquired in 9 survey areas in and around the Kingmere MCZ, during the peak breeding season, to identify and locate black bream nests.

The multibeam was processed for bathymetry and backscatter, providing imagery at 10cm resolution, enabling nest identification (approximately 1m in diameter) due to risen sediment around the nest and the cleared hard rock surface. The data was interpreted, and nests classified in terms of density.

Post-processing of the geophysical data determined transects for subsequent drop-down video (DDV) surveys. Three DDV surveys were undertaken over three months to ground truth the multibeam results and to determine the seasonal extent of black bream spawning.

The ABPmer DDV system was used for all surveys, utilising a C-Tecnics CT3020 SLV video and digital stills camera to capture high-resolution imagery. To provide wider coverage of the seabed, three Go-Pro Hero 7 cameras were attached to the sides of the DDV frame.

The video and photographic data from the surveys were assessed for the distribution and abundance of black bream nests and the presence of black bream eggs, where present, during the spawning season.

ABPmer's surveyors support marine developments with a comprehensive understanding of habitats, species and the seabed, delivering a tailored survey programme to suit project requirements. Learn more about our ecological survey and hydrographic-geophysical survey capability.

Vicky West

+44 (0)23 8071 1851

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