Elemental Analysis and Nutritional Value of Seaweed from the East Coast of KwaZulu-Natal, South Africa

ABSTRACT

Seaweed, biologically and phycologically referred to as algae, is classified as Rhodophyta (red), Chlorophyta (green), and Ochrophyta (brown). In this study, the concentrations of 13 elements (As, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Se, and Zn) were investigated for 14 seaweed species of varying classes (Amphiroa bowerbankii, Ceramium virgatum, Dichotomaria tenera, Ellisolandia (Coralline) elongata, Gelidium abbottiorum, Gracilaria canaliculata, Jania rubens, and Jania (Haliptylon) squamata of the Rhodophyta (red); Caulerpa filiformis, Codium capitatum, Halimeda cuneata, and Ulva rigida of the Chlorophyta (green); and Cystoseira myrica and Sargassum elegans of the Ochrophyta (brown) to determine the nutritional value of seaweed based on its medicinal properties, industrial importance, and natural abundance. The elemental distribution in seaweeds was in decreasing order of Ca > Mg > Fe > Cu > Mn > Zn > Cr > Co > Se > As > Pb > Ni > Cd. All edible species contained high levels of macro and microelements with the corali sp. accumulating high levels of Ca. Of the edible seaweeds characterized, only three (G. abbottiorum, E. (Coralline) elongate and C. virgatum) are suitable for human consumption due to high levels of As, Cd, and Pb present in the other species. These three species are also rich in essential nutrients, specifically C. virgatum, which is high in Cu and Se. Hierarchical cluster analysis showed a clear similarity in distribution of essential and toxic elements in similar classes of seaweed.

KEYWORDS:

• Chlorophyta
• elemental analysis
• Ochrophyta
• Rhodophyta
• tolerable upper intake levels