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Original Research - Human Influences - 16/10/24

Records reveal the vast historical extent of European oyster reef ecosystems

Anthropogenic activities have impacted marine ecosystems at extraordinary scales. Biogenic reef ecosystems built by the European flat oyster (Ostrea edulis) typically declined before scientific monitoring. The past form and extent of these habitats thus remains unknown, with such information potentially providing valuable perspectives for current management and policy. Collating >1,600 records published over 350 years, we created a map of historical oyster reef presence at the resolution of 10 km2 across its biogeographic range, including documenting abundant reef habitats along the coasts of France, Denmark, Ireland and the United Kingdom. Spatial extent data were available from just 26% of locations yet totalled >1.7 million hectares (median reef size = 29.9 ha, range 0.01–1,536,000 ha), with 190 associated macrofauna species from 13 phyla described. Our analysis demonstrates that oyster reefs were once a dominant three-dimensional feature of European coastlines, with their loss pointing to a fundamental restructuring and ‘flattening’ of coastal and shallow-shelf seafloors. This unique empirical record demonstrates the highly degraded nature of European seas and provides key baseline context for international restoration commitments.

Ruth H. Thurstan, Hannah McCormick, Joanne Preston, Elizabeth C. Ashton, Floris P. Bennema, Ana Bratoš Cetinić, Janet H. Brown, Tom C. Cameron, Fiz da Costa, David W. Donnan, Christine Ewers, Tomaso Fortibuoni, Eve Galimany, Otello Giovanardi, Romain Grancher, Daniele Grech, Maria Hayden-Hughes, Luke Helmer, K. Thomas Jensen, José A. Juanes, Janie Latchford, Alec B. M. Moore, Dimitrios K. Moutopoulos, Pernille Nielsen, Henning von Nordheim, Bárbara Ondiviela, Corina Peter, Bernadette Pogoda, Bo Poulsen, Stéphane Pouvreau, Callum M. Roberts, Cordula Scherer, Aad C. Smaal, David Smyth, Åsa Strand, John A. Theodorou & Philine S. E. zu Ermgassen
Original Research - Human Influences - 16/08/24

Georectifying drone image data over water surfaces without fixed ground control: Methodology, uncertainty assessment and application over an estuarine environment

Light-weight consumer-grade drones have the potential to provide geospatial image data to study a broad range of oceanic processes. However, rigorously tested methodologies to effectively and accurately geolocate and rectify these image data over mobile and dynamic water surfaces, where temporally fixed points of reference are unlikely to exist, are limited. We present a simple to use automated workflow for georectifying individual aerial images using position and orientation data from the drone’s on-board sensor (i.e. direct-georectification). The presented methodology includes correcting for camera lens distortion and viewing angle and exploits standard mathematics and camera data processing techniques. The method is…

Jennifer Watts, Thomas Holding, Karen Anderson, Thomas G. Bell, Bertrand Chapron, Craig Donlon, Fabrice Collard, Neill Wood, David Walker, Leon DeBell, James P. Duffy, Jamie Shutler