Menandro Pedro S, Misiuk Benjamin, Brown Craig J, Bastos Alex C
Marine Geosciences Lab (Labogeo), Departamento de Oceanografia E Ecologia, Universidade Federal do Espírito Santo, Vitória, ES, Brazil.
Seascape Ecology and Mapping Lab, Department of Oceanography, Dalhousie University, Halifax, NS, Canada.
Sci Rep. 2023 Nov 18;13(1):20220. doi: 10.1038/s41598-023-46240-7.
Acoustic backscatter has been used as a tool to map the seafloor in greater detail and plays an increasingly important role in seafloor mapping to meet multiple ocean management needs. An outstanding challenge to the use of backscatter for seafloor mapping is the distinction between acoustically similar substrates, such as mixed sediments from rhodoliths. Rhodolith beds are a biogenic substrate that provides important ecological services, and are typically classified as a single categorical substrate type-though nodules coverage may be spatially variable. Recently, multispectral acoustic backscatter has demonstrated great potential to improve thematic seafloor mapping compared to single-frequency systems. This work employs multispectral multibeam backscatter and underwater imagery to characterize and map rhodolith beds in the Costa das Algas Marine Protected Area (Brazil). A support vector machine classifier was used to classify multifrequency backscatter mosaics according to rhodolith classes identified from underwater imagery. Results suggest that multispectral backscatter is effective both in providing information for mapping different proportions of rhodolith coverage and in predicting the presence or absence of these nodules. The backscatter of the lowest frequency was the most useful for distinguishing variable proportions of rhodolith coverage, and the two higher frequencies were better predictors of presence and absence.
声学后向散射已被用作一种更详细绘制海底地图的工具，并且在满足多种海洋管理需求的海底测绘中发挥着越来越重要的作用。将后向散射用于海底测绘面临的一个突出挑战是区分声学特性相似的海底基质，例如来自红藻岩的混合沉积物。红藻岩床是一种提供重要生态服务的生物源基质，通常被归类为单一的分类基质类型，尽管结核覆盖率在空间上可能存在变化。最近，与单频系统相比，多光谱声学后向散射在改进海底专题测绘方面已显示出巨大潜力。这项工作利用多光谱多波束后向散射和水下图像来表征和绘制巴西阿尔加斯海岸海洋保护区的红藻岩床。使用支持向量机分类器根据从水下图像识别出的红藻岩类别对多频后向散射镶嵌图进行分类。结果表明，多光谱后向散射在为绘制不同比例的红藻岩覆盖率提供信息以及预测这些结核的存在与否方面均有效。最低频率的后向散射对于区分红藻岩覆盖率的不同比例最有用，而两个较高频率在预测存在与否方面表现更好。
