First mesophotic Ecklonia radiata (Laminariales) records within the iSimangaliso Wetland Park marine-protected area, east coast, South Africa

Abstract

A dense Ecklonia radiata (Laminariales) kelp forest extending at least 35 km has been found between 45 and 60 m depth range within the mesophotic zone inside the iSimangaliso marine-protected area (MPA) at the iSimangaliso Wetland park World Heritage Site on the east coast of South Africa. This is the first visual confirmation of the occurrence of E. radiata beds in subtropical South Africa, in an area situated between the tropical and subtropical bioregions, in an area that spans the Natal and Delagoa bioregions of the south-western Indian Ocean, more than 350 km north of its previously documented South African range. The kelp was found to be present across the length of the MPA, but dense beds were present only in the southern Natal bioregion, with sparse occurrences observed elsewhere on soft-coral and sponge-dominated reefs in the upper mesophotic zone. The footage was collected in November 2020, May 2021 and November 2022 during remotely operated vehicle and drop camera surveys of the mesophotic zone inside the MPA. This discovery adds to the body of knowledge on the global distribution of Laminariales populations in deep tropical and subtropical settings and the diversity of habitats within South Africa's largest coastal MPA.

Well-known mesophotic kelp populations in the iSimangaliso Wetland Park marine-protected area, east coast, South Africa

“…In a recent short communication titled ‘First mesophotic Ecklonia radiata (Laminariales) records within the iSimangaliso Wetland Park marine-protected area, east coast, South Africa’ by Qwabe et al . (2023), the assertion of discovering a mesophotic population of kelp in the iSimangaliso Wetland Park is made by the authors. However, contrary to this claim, published literature has long recognized the presence of a mesophotic population of Ecklonia radiata in the extreme northeast of South Africa, where the iSimangaliso Wetland Park is situated.…”

“…Qwabe et al . (2023) make a sweeping claim that the species is recorded for the first time north of its recognized range, erroneously citing Port Edward as the eastern distribution limit for the species in southern Africa. Bolton and Anderson (1987) posit that pinpointing the eastward range limit of E. radiata in South Africa is challenging, based on observations in deeper waters off Natal (now Kwa-Zulu Natal).…”

“…It is worth noting that Qwabe et al . (2023) cite a chapter from De Clerck et al . (2005), but appear not to have consulted it thoroughly, as the pertinent information is clearly present in the cited literature.…”

“…Qwabe et al . (2023) proceed to formulate hypotheses regarding the dispersal history and origin of the supposedly newly discovered population, relying on mtDNA barcodes as published in Coleman et al . (2022).…”

“…Additionally, the study by Qwabe et al . (2023) is marked by numerous inaccuracies, with many instances where source information is incorrectly cited. Facts are often misattributed, and sources are either incorrectly cited or do not cite the primary literature.…”