Primary Research Paper

Hydrobiologia

, Volume 680, Issue 1, pp 265-284

First online:

High resolution mapping of sediment organic matter from acoustic reflectance data

  • Natalia SerpettiAffiliated withMarine Scotland – Science Laboratory AberdeenOceanlab, Institute of Biological and Environmental Sciences, Ecology, University of Aberdeen Email author 
  • , Mike HeathAffiliated withMarine Scotland – Science Laboratory AberdeenDepartment of Mathematics and Statistics, University of Strathclyde
  • , Malcolm RoseAffiliated withMarine Scotland – Science Laboratory Aberdeen
  • , Ursula WitteAffiliated withOceanlab, Institute of Biological and Environmental Sciences, Ecology, University of Aberdeen

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Abstract

Spatial mapping of the marine environment is challenging when the properties concerned are difficult to measure except by shore-based analysis of discrete samples of material, usually from sparsely distributed sites. This is the case for many seabed sediment properties. We developed an indirect approach to mapping the organic content of coastal sediments from hydro-acoustic reflectance data. The basis was that both organic matter and acoustic reflectance are related to sediment type and grain size composition. Hence there is a collateral relationship between organic matter content and reflectance properties which can be exploited to enable high resolution mapping. We surveyed an area of seabed off the east coast of Scotland using a vessel mounted single beam echosounder with RoxAnn signal processing. Organic carbon, nitrogen and phytoplankton pigment contents were then measured in material from grab and core samples collected at intervals over a year. Relationships between the organic components and hydro–acoustic characteristics were derived by general additive models, and used to construct high resolution maps from the acoustic survey data. Our method is an advance on traditional interpolation techniques sparse spatial data, and represents a generic approach that could be applied to other properties.

Keywords

Single beam RoxAnn Ground truthing survey Hardness Roughness Total organic carbon (TOC) Total nitrogen (TN) Chlorophyll-a Pheophytin-a Scotland UK