Rhodolith Bed Discovered off the South African Coast

Toufiek Samaai,Luther A Adams,Gavin W Maneveldt,Denham Parker,Sven Kerwath,Natasha Karenyi,Andrew Green

doi:10.3390/d12040125

Toufiek Samaai, Luther A Adams + Show 5 more

Open Access

https://doi.org/10.3390/d12040125

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Abstract

Rhodolith beds have not previously been recorded in South Africa. A multidisciplinary research effort used remote sampling tools to survey the historically unexplored continental shelf off the Eastern Cape coast of South Africa. A rhodolith bed, bearing both living and dead non-geniculate coralline red algae, was discovered in the 30–65 m depth range off the Kei River mouth in the newly proclaimed Amathole Offshore Marine Protected Area. Some of the rhodolith forming coralline algal specimens were identified as belonging to at least three genera based on their morphology and anatomy, namely, Lithophyllum, Lithothamnion and a non-descript genus. Rhodolith mean mass and diameter were 44.85 g ± 34.22 g and 41.28 mm ± 10.67 mm (N = 13), respectively. Remotely operated vehicle (ROV) imagery revealed a suite of epibenthic red macroalgae associated with the rhodolith bed. Taxonomy, vertical structure and distribution of rhodoliths in South Africa require further investigation.

Highlights

Rhodoliths are live and dead aggregations of free-living non-geniculate coralline algae (Corallinales, Hapalidiales, Sporolithales: Corallinophycidae) from the phylum Rhodophyta [1]
Epibiotic morphospecies obtained from remotely operated vehicle (ROV) imagery were classified to the from underwater imagery
Coast-parallel, bifurcating and symmetrical large wave-formed dunes co-occurred with rhodolith beds (Figure 6A) and were bordered along the coastal wavelength) co-occurred with rhodolith beds (Figure 6A) and were bordered along the coastal strike by strike by several coast-elongate gravel ribbons orientated with the Agulhas Current (Figure 6B)

Summary

Introduction

Rhodoliths are live and dead aggregations of free-living non-geniculate coralline algae (Corallinales, Hapalidiales, Sporolithales: Corallinophycidae) from the phylum Rhodophyta [1] They are important producers of calcium carbonate and are ecosystem engineers that support a high diversity of benthic fauna and algal communities [1,2,3,4,5]. Rhodolith beds form habitats that represent an important transition between largely featureless, soft substrates and hard-cemented rocky reefs Their three dimensional structure supports vast numbers of organisms from several different phyla [5,19], including polychaetes [20], barnacles [21], macroalgae [5,22] and molluscs [23].

Methods

Speculated

A Reson echo dredge and remotely operated were used to survey continental

Rhodolith Morphology and Age

Cross-section

Non-geniculate Coralline Algal Identifications

Discussion

Conclusions