Comparison of the diversity and biomass of beach-cast seaweeds from NE and SE Brazil

ABSTRACT

Stranded seaweeds are reported worldwide; along the Brazilian coast, the occurrence of beach-cast seaweeds is increasing. In this study the diversity, coverage and biomass of beach-cast seaweeds were compared on the north-eastern (NE) and south-eastern (SE) coasts of Brazil. In total 110 taxa were identified: 80 Rhodophyceae, 13 Phaeophyceae and 17 Chlorophyceae. While the NE coast had higher species richness, the SE beaches exhibited higher coverage and biomass, predominantly Phaeophytes within the Dictyotales. The identified taxa were attributed to five functional-form groups and their respective frequencies were calculated and analysed. In Brazil, corticated species displayed the highest frequency at all study sites, especially Emboaca Beach, whereas the corticated foliose group was more frequent on Candeias, Itaoca and Pontal Beaches. A permutational analysis of variance revealed significant differences in coverage and biomass of the macroalgal assemblages across beaches. A homogeneity of multivariate dispersions indicated that these parameters also differed significantly between the NE and SE coasts, with a marked dissimilarity between the beaches studied. Our results will contribute to a better understanding of the biodiversity and biomass of beach-cast seaweeds for possible future economic use (e.g. as fertilizer) in a region where local incomes are low.

KEYWORDS:

• Macroalgal bloom
• macroalgal stranding
• marine biodiversity
• morphotypes
• stranded biomass

Acknowledgements

We want to record our appreciation to Enrique Reynaldo de la Cruz for his valuable and constant collaboration during the data processing. The authors are also grateful for the anonymous comments of the reviewers, which contributed significantly to its improvement.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

The following supplementary material is accessible via the Supplementary Content tab on the article’s online page at https://doi.org/10.1080/09670262.2021.2003867

Supplementary table S1. Macroalgal species recorded at the four sampling sites with their frequency of occurrence and functional-form group according to Steneck & Dethier (1994).

Author contributions

M.I.L.G. Cavalcanti: conceptualization, methodology, formal analysis, investigation, writing original draft, reviewing and editing manuscript; P.M. González-Sánchez: methodology, data curation, formal analysis, review and editing manuscript. M. T. Fujii: resources, supervision, review and editing manuscript.

Additional information

Funding

This study is part of the project entitled “Sustainable and healthy food and feed ingredients from seaweeds – SeaFeed” and was carried out within the framework of the German National Research Strategy Bioeconomy 2030 – Bioeconomy International 2015 – of the Federal Ministry of Education and Research (BMBF). Partially funded by the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP-2016/50370-7) and by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, 440523/2015-0). MTF thanks CNPq for the Productivity Fellowship (304899/2017-8).