EM2040C Multibeam sonar water-column data (200, 300, 400 kHz) acquired over an experimental patch of Giant kelp (Macrocystis pyrifera)

Multibeam sonar water-column data show potential for the detection of aquatic vegetation that extends significantly from the seabed, such as kelp, and may therefore contribute to improving marine habitat mapping. In order to determine if such data can be used to detect kelp and estimate their biomass, we acquired a comprehensive water-column dataset over a controlled kelp site.

The experimental site was a collection of fourteen Giant kelp (Macrocystis pyrifera) plants harvested from a nearby forest and arranged on an area of seafloor previously bare, after having been measured and weighed at port. The arrangement consisted in a 4 m by 4 m quadrat with individual 1 m wide cells, and one plant set at random per cell.

The water-column dataset was acquired with a Kongsberg EM2040C MBES at several frequencies (200, 300, and 400 kHz) and pulse lengths (25, 50, and 100 μs). For each combination of these settings, we acquired data by running the vessel three times on two parallel paths with opposite direction on either side of the surface canopy. These 3 replicates in 2 directions of data recorded with 9 different settings resulted in 54 data files. The data acquisition process was repeated after removing half of the plants, to simulate a thinner forest, leading to another set of 54 data files.

The Giant kelp plants produced evident echoes in the water-column data at all settings. This dataset may be used to develop water-column data processing methodologies (such as methods attempting at filtering the acoustic noise), or models to relate EM2040C water-column data to kelp biomass.

Multibeam sonar water-column data show potential for the detection of aquatic vegetation that extends significantly from the seabed, such as kelp, and may therefore contribute to improving marine habitat mapping. In order to determine if such data can be used to detect kelp and estimate their biomass, we acquired a comprehensive water-column dataset over a controlled kelp site.

The experimental site was a collection of fourteen Giant kelp (Macrocystis pyrifera) plants harvested from a nearby forest and arranged on an area of seafloor previously bare, after having been measured and weighed at port. The arrangement consisted in a 4 m by 4 m quadrat with individual 1 m wide cells, and one plant set at random per cell.

The water-column dataset was acquired with a Kongsberg EM2040C MBES at several frequencies (200, 300, and 400 kHz) and pulse lengths (25, 50, and 100 μs). For each combination of these settings, we acquired data by running the vessel three times on two parallel paths with opposite direction on either side of the surface canopy. These 3 replicates in 2 directions of data recorded with 9 different settings resulted in 54 data files. The data acquisition process was repeated after removing half of the plants, to simulate a thinner forest, leading to another set of 54 data files.

The Giant kelp plants produced evident echoes in the water-column data at all settings. This dataset may be used to develop water-column data processing methodologies (such as methods attempting at filtering the acoustic noise), or models to relate EM2040C water-column data to kelp biomass.

Disciplines

Environment

Keywords

multibeam, sonar, echosounder, water-column, water column, specular, seabed mapping, benthic habitat, Giant kelp, macrocystis

Location

-38.41N, -38.4S, 142.49E, 142.51W

Devices

Kongsberg EM2040C multibeam echo-sounder. Serial number 102.

Data

FileSizeFormatProcessingAccess
Kongsberg EM2040C raw data files (FULL dataset - 54 lines)
3 GoKongsberg .allRaw data
Experiment logbook
507 KoDOC, DOCX
Photos of the individual plants
90 MoIMAGE
Other photos of the experiment
69 MoIMAGE
Settings for each raw data file
5 KoCSV
Kongsberg EM2040C raw data files (dataset EXTRACT - 2 first lines)
80 MoKongsberg .allRaw data
How to cite
Schimel Alexandre, Daniel Ierodiaconou, Sean Blake, Mahala Ebery, Adam Pope (2023). EM2040C Multibeam sonar water-column data (200, 300, 400 kHz) acquired over an experimental patch of Giant kelp (Macrocystis pyrifera). SEANOE. https://doi.org/10.17882/72579

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