17 May 2021

17 May 2021

Review status: this preprint is currently under review for the journal ESSD.

Modelling seabed sediment physical properties and organic matter content in the Firth of Clyde

Matthew C. Pace1, David M. Bailey1, David W. Donnan2, Bhavani E. Narayanaswamy3, Hazel J. Smith4, Douglas C. Speirs4, William R. Turrell5, and Michael R. Heath4 Matthew C. Pace et al.
  • 1Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
  • 2NatureScot, Perth, PH1 3EW, UK
  • 3Scottish Association for Marine Science, Oban, PA37 1QA, UK
  • 4Department of Mathematics and Statistics, University of Strathclyde, Glasgow, G1 1XH, UK
  • 5Marine Scotland Science, Aberdeen, AB11 9DB, UK

Abstract. High quality quantitative maps of seabed sedimentary physical and geochemical properties have numerous research and conservation applications, including habitat and ecosystem modelling, marine spatial planning and ecosystem service mapping. However, such maps are lacking for many ecologically and economically important marine areas. Using legacy data supplemented by measurements from recent benthic surveys, modelled hydrodynamic variables and high resolution bathymetry, quantitative maps for the top 10 cm of seabed sediment were generated via a combination of statistical and machine-learning techniques for the Firth of Clyde, a semi-enclosed coastal sea on the west coast of Scotland. The maps include sediment fractions of mud, sand and gravel, whole-sediment median grain size, sediment permeability and porosity, rates of natural seabed abrasion, and sediment particulate organic carbon and nitrogen content. Properties were mapped over an unstructured grid, so that very high resolutions were achieved close to the coastlines, where sediments may be expected to be spatially heterogeneous.

Overall, the maps reveal extensive areas of very low sediment permeability coupled with low rates of natural seabed disturbance. Moreover, muddy sediments in the inner Firth of Clyde, Inchmarnock Water and the sea lochs are enriched in organic carbon and nitrogen relative to the sediments of the outer Firth of Clyde. As a demonstration of the value of these maps, the standing stock of organic carbon and nitrogen in the surficial sediments of the Clyde was calculated. The Clyde stores 3.42 and 0.33 million tonnes of organic carbon and nitrogen in the top 10 cm of seabed sediment, respectively, substantially contributing to Scotland’s coastal and shelf blue carbon stocks. Data products are available from:

Matthew C. Pace et al.

Status: open (until 15 Jul 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on essd-2021-23', Craig Smeaton, 30 May 2021 reply
  • RC1: 'Comment on essd-2021-23', Anonymous Referee #1, 02 Jun 2021 reply

Matthew C. Pace et al.

Data sets

High resolution seabed sedimentology data for the Firth of Clyde Heath, M. and Pace, M.

Matthew C. Pace et al.


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Short summary
We present synthetic maps of continuous properties of seabed sediments in the Firth of Clyde, SW Scotland. The data include proportions of mud, sand and gravel fractions, whole-sediment median grain size, permeability, porosity, organic carbon and nitrogen content, and rates of natural disturbance by tidal currents. We show that the Firth stores 3.42 and 0.33 million tonnes of organic carbon and nitrogen respectively in the upper 10 cm of sediment.