Changes in holopelagic Sargassum spp. biomass composition across an unusual year

• 成果类型: Article
• 署名作者: Machado, Carla Botelho; Marsh, Robert; Hargreaves, Jessica K.; Oxenford, Hazel A.; Maddix, Gina-Marie; Webber, Dale F.; Webber, Mona; Tonon, Thierry
• 署名单位: University of York - UK; University of Southampton; NERC National Oceanography Centre; University of York - UK; University West Indies Mona Jamaica; University West Indies Cave Hill Campus; University West Indies Mona Jamaica; University West Indies Mona Jamaica
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-14187
• DOI: 10.1073/pnas.2312173121
• 发表日期: 2024-05-28
• 关键词: atlantic; phaeophyceae

摘要

The year 2021 marked a decade of holopelagic sargassum (morphotypes Sargassum natans I and VIII, and Sargassum fluitans III) stranding on the Caribbean and West African coasts. Beaching of millions of tons of sargassum negatively impacts coastal ecosystems, economies, and human health. Additionally, the La Soufri & egrave;re volcano erupted in St. Vincent in April 2021, at the start of the sargassum season. We investigated potential monthly variations in morphotype abundance and biomass composition of sargassum harvested in Jamaica and assessed the influence of processing methods (shade - drying vs. frozen samples) and of volcanic ash exposure on biochemical and elemental components. S. fluitans III was the most abundant morphotype across the year. Limited monthly variations were observed for key brown algal components (phlorotannins, fucoxanthin, and alginate). Shade - drying did not significantly alter the contents of proteins but affected levels of phlorotannins, fucoxanthin, mannitol, and alginate. Simulation of sargassum and volcanic ash drift combined with age statistics suggested that sargassum potentially shared the surface layer with ash for - 50 d, approximately 100 d before stranding in Jamaica. Integrated elemental analysis of volcanic ash, ambient seawater, and sargassum biomass showed that algae harvested from August had accumulated P, Al, Fe, Mn, Zn, and Ni, probably from the ash, and contained less As. This ash fingerprint confirmed the geographical origin and drift timescale of sargassum. Since environmental conditions and processing methods influence biomass composition, efforts should continue to improve understanding, forecasting, monitoring, and valorizing sargassum, particularly as strandings of sargassum show no sign of abating.