Abstract
Understanding how fish associate with habitats across marine landscapes is crucial to developing effective marine spatial planning (MSP) in an expanding and diversifying ocean economy. Globally, anthropogenic pressures impact the barely understood temperate mesophotic ecosystems and South Africa’s remote Amathole shelf is no exception. The Kei and East London region encompass three coastal marine protected areas (MPAs), two of which were recently extended to the shelf-edge. The strong Agulhas current (exceeding 3 m/s), which runs along the narrow shelf exacerbates sampling challenges. For the first time, a remotely operated vehicle (ROV) surveyed fish and their associated habitats across the shelf. Results indicated fish assemblages differed between the two principle sampling areas, and across the shelf. The number of distinct fish assemblages was higher inshore and on the shelf-edge, relative to the mid-shelf. However, the mid-shelf had the highest species richness. Unique visuals of rare Rhinobatos ocellatus (Speckled guitarfish) and shoaling Polyprion americanus (wreckfish) were collected. Visual evidence of rhodolith beds, deep-water lace corals and critically endangered endemic seabreams were ecologically important observations. The ROV enabled in situ sampling without damaging sensitive habitats or extracting fish. This study provided information that supported the Amathole MPA expansions, which extended protection from the coast to beyond the shelf-edge and will guide their management. The data gathered provides baseline information for future benthopelagic fish and habitat monitoring in these new MPAs.
Highlights
Understanding how fish associate with habitats across marine landscapes is crucial to developing effective marine spatial planning (MSP) in an expanding and diversifying ocean economy
A total of 54 h of footage was collected from 42 remotely operated vehicle (ROV) transect dives (Supplementary Table S1) which translates to a total of 117 sampling sites
This study collected unprecedented observations of Polyprion americanus (Wreckfish) schooling as well as Rhinobatos ocellatus (Speckled guitarfish), which were both listed as data deficient by the IUCN red list[30] (Fig. 2e,f)
Summary
Understanding how fish associate with habitats across marine landscapes is crucial to developing effective marine spatial planning (MSP) in an expanding and diversifying ocean economy. If fish assemblages are associated with specific habitats and environmental features, this information can be used for fish distribution p rojections[2] This understanding is valuable for marine spatial planning (MSP), where information from different models can help strategize to mitigate the effects of anthropogenic pressures[3]. Anthropogenic pressures are rapidly altering marine ecosystems, including the scarcely understood mesophotic (between 30 and 150 m deep)[4] and the ‘rariphotic’ (150–300 m depth) z one[5]. A better understanding of the distribution of fish and habitat through the mesophotic zone[10,14] without causing damage to the habitat or extracting s pecies[15] This makes it an ideal method for sampling areas of potential conservation value or protected areas[15]. The new Amathole Offshore MPA extends protection to the mesophotic ecosystems in the region for the first t ime[22] (Fig. 1)
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