The value of multibeam bathymetry in marine spatial planning in South Africa: A review

Abstract

Given a growing global population and shift to embrace the blue economy, a need for marine spatial planning (MSP) has emerged in  South Africa to sustainably resolve the rising conflicts over the use of marine and seabed resources and services. A well-developed  marine spatial plan yields numerous ecological, social and economic benefits. These are achieved through mediating between spatially  conflicting economic drivers’ interests (e.g. commercial fishing, tourism, mining), preventing their activities from compromising  thresholds of an environment’s sustainability. Within the MSP framework, high-resolution geospatial datasets are required to document  and describe the seabed in the highest possible detail. At any scale, integrated analysis of seabed geomorphology and habitats is  anticipated to greatly improve the understanding of ecosystem functioning from a multidisciplinary perspective, whilst improving MSP procedures and management of marine space. South Africa is the first of few African countries to have an approved and implemented  MSP framework, but is still somewhat behind globally in implementing large-scale regional hydroacoustic surveys to cover the country’s  vast offshore territory. The deficiency of hydroacoustic surveys is perhaps due to a relative lack of funds and poor communication about  the value of multibeam echo-sounder (MBES) derived data, whilst marine geoscience remains a scarce skill in the country. This review  paper presents a geological perspective of MSP and explores (1) the value that seabed mapping offers MSP specifically and (2) the need  to increase seabed mapping with MBES, using a recently initiated project from the South African east coast as a case study.

Significance: The collected MBES data (our case study) provides unprecedented seabed detail of the complex reef habitat and adjacent areas within  specific management zones of the uThukela Banks Marine Protected Area. We reveal seabed features and their spatial distribution at a  scale not possible using earlier (singlebeam) seabed mapping techniques. These high-resolution data will enable a better understanding  of east coast marine habitats whilst contributing to improved spatial management of areas within and around the uThukela Banks    Marine Protected Area.