Hydrodynamics and hydroacoustic mapping of a benthic seafloor in a coarse grain habitat of the German Bight
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Coarse-grained hard substrate areas with grain sizes up to very coarse boulder (> 2 m) are very rare in the German North Sea. The “Helgoländer Steingrund” is one of such highly biodiverse areas: it is characterized by a half-moon-shaped hard substrate ridge, which subdivides the site into a more exposed (westerly) and a less exposed (easterly) flank, characterized by a mixture of sand and gravel deposits. Sonar systems, underwater videos, and bottom samples were used for mapping and classifying the abiotic and biotic components in such very patchy and coarse-grained habitat. Three main seabed types (sand, gravel, and hard substrate) were identified, based on acoustic backscatter data. The additional information coming from underwater videos and sediment bottom sample analysis allowed the description of six different seabed types, which included both the abiotic (sediments, morphology, etc.) and biotic components. The flanks of the ridge and their transition to the surrounding soft-ground areas were characterized by a distinct dominance of the bryozoa F. foliacea and A. diaphanum on the western and on the eastern side, respectively. Morphology and hydrodynamics are likely responsible for such zonation. This is proved by the outcomes of the Acoustic Doppler Current Profiler data, which showed the general flow pattern across the ridge and even resolved the local variability of current pattern, dependent on the tidal stage and bottom relief.
This study is financed by the German Research Foundation (DFG) and is part of the INTERCOAST project, which is a collaboration of the University of Bremen, the Senckenberg Institute in Wilhelmshaven, and the University of Waikato.
The authors would like to thank the crew of the RV Senckenberg for the support on the vessel.
Many thanks go to the Federal Maritime and Hydrographic Agency (BSH) Hamburg which provided the (MBES) multibeam data for the bathymetry.
The authors are grateful to Astrid Raschke for the grain-size analysis, to Maik Wilsenack for the technical support, and to our student assistant Vanessa Köhler.
The data reported in this paper will be archived in Pangaea (www.pangaea.de).
- Arendartchuk F, Prado MFV, Bonetti J (2017) Classification of geomorphological in Pântano do Sul Bay (SC) from side-scan sonar images. 2017 IEEE/OES Acoustics in Underwater Geosciences Symposium (RIO Acoustics)Google Scholar
- Bartholomä A, Holler P, Schrottke K, Kubicki A (2011) Acoustic habitat mapping in the German Wadden Sea - comparison of hydro-acoustic devices. J Coast Res Spec Issue 64:1–5Google Scholar
- BFN (Federal Agency for Nature Conservation) (2018) Die Meeresschutzgebiete in der deutschen ausschließlichen Wirtschaftszone der Nordsee - Beschreibung und Zustandsbewertung, (2. überarb. Auflage). BfN-Report, 477, 486 pGoogle Scholar
- Brezina J (1979) Particle size and settling rate distributions of sand-sized materials. PARTEC - 2nd European Symposium on Particle Characterization. Nürnberg, 1-47Google Scholar
- Dederer G, Boos K, Kanstinger P, Krone R, Schneider C, Beher J, Kuhlenkamp R, Kind B (2015) Tauchuntersuchung des “Steingrund” bei Helgoland (FFH DE 1714 - 391) und Konzeptentwicklung eines Tauch Monitorings für den FFH Lebensraumtyp Riff. Final report, 74 pGoogle Scholar
- Dyrynda P (1994) Hydrodynamic gradients and bryozoan distributions within an estuarine basin (Poole Harbour,UK). Olsen & Olsen, FredensborgGoogle Scholar
- Ellingsen KE, Gray JS, Bjørnbom E (2002) Acoustic classification of seabed habitats using the QTC VIEW system. J Mar Sci 59(4):825–835Google Scholar
- Feldens P, Schulze I, Papenmeier S, Schönke M, Schneider von Deimling J (2018) Improved interpretation of marine sedimentary environments using multi-frequency multibeam backscatter data. GeosciencesGoogle Scholar
- Freitas R, Silva S, Quintino V, Rodrigues AM, Rhynas KP, Collins WT (2003) Acoustic seabed classification of marine habitats: studies in the western coastal-shelf area of Portugal. J Mar Sci 60:599–608Google Scholar
- Holler P, Markert E, Bartholomä A, Capperucci R, Hass CH, Kröncke I, Mielk F, Reimers CH (2017) Tools to evaluate seafloor integrity: comparison of multi-device acoustic seafloor classifications for benthic macrofauna-driven patterns in the German Bight, southern North Sea. Geo-Mar Lett 37(2):93–109CrossRefGoogle Scholar
- Lurton X (2002) An introduction to underwater acoustics. Principle and applications, Springer, 347 ppGoogle Scholar
- Migné A, Davoult D (2002) Experimental nutrition in the soft coral Alcyonium digitatum (Cnidaria: Octocorallia): removal rate of phytoplankton and zooplankton. Cah Biol Mar 43(1):9–16Google Scholar
- Preston JM, Collins WT (2000) Bottom classification in very shallow water by high-speed data acquisition. Oceans Conference Record (IEEE), 2, 1277, 1282 vol.2. https://doi.org/10.1109/OCEANS.2000.881778
- Quester Tangent (2004) QTC IMPACT user manualGoogle Scholar
- Rachor E & Nehmer P (2003) Erfassung und Bewertung ökologisch wertvoller Lebensräume in der Nordsee-Abschlussbericht für das F + E-Vorhaben FKZ 899 85 310. Report, Bundesamt für Naturschutz, 175 ppGoogle Scholar
- Schulz H (1983) Der Steingrund bei Helgoland - Restsedimente einer saaleeiszeitlichen Endmoräne. Meyniana 35:43–53Google Scholar
- Schwarzer K, Ricklefs K, Bartholomä A, Zeiler M (2008) Geological development of the North Sea and the Baltic Sea. Die Küste 74:1–17Google Scholar
- Zeiler M, Schwarzer K, Bartholomä A, Ricklefs K (2008) Seabed morphology and sediment dynamics. Die Küste 74:31–44Google Scholar