{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,14]],"date-time":"2026-04-14T16:29:16Z","timestamp":1776184156802,"version":"3.50.1"},"reference-count":57,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2025,3,1]],"date-time":"2025-03-01T00:00:00Z","timestamp":1740787200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Funda\u00e7\u00e3o Grupo Botic\u00e1rio de Prote\u00e7\u00e3o \u00e0 Natureza","award":["0912_20112"],"award-info":[{"award-number":["0912_20112"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Plants"],"abstract":"<jats:p>Sargassum is an important primary producer of rocky bottom communities in coastal ecosystems. Like other parts of the planet, benthic populations of S. natans from Ilha Grande Bay (IGB), southeastern Brazil, have been suffering from different forms of natural and anthropogenic disturbances, in particular increasing seawater temperatures. The aim of this study was to understand the effects of temperature on the photosynthetic performance of S. natans using the pulse amplitude modulated (PAM) fluorometry. In the field experiments, the occurrence of photoprotection resulted in a difference between the effective and maximum quantum yields [(\u0394F (F\u2019m \u2212 Fs)\/F\u2019m and Fv\/Fm, respectively) that was maximized at noon. The stress induced by incubation at 32\u201335 \u00b0C caused a decrease in Fv\/Fm by 33% on the first day and approximately 20% on subsequent days. In the laboratory, using two co-occurred species of S. natans and Padina gymnospora, we verified that the photosynthetic apparatus of S. natans collapses at 34 \u00b0C. The fate of the energy absorbed by photosystem II (PSII) antenna showed that, in S. natans, photochemical activity and non-photochemical quenching of chlorophyll fluorescence (NPQ) drastically decrease, and only the passive dissipation in the form of heat and fluorescence remains. Our results indicate the disappearance of the NPQ photoprotection at 34 \u00b0C before the decline of Fv\/Fm as the reason for the collapse of photochemistry of Sargassum.<\/jats:p>","DOI":"10.3390\/plants14050759","type":"journal-article","created":{"date-parts":[[2025,3,3]],"date-time":"2025-03-03T10:15:03Z","timestamp":1740996903000},"page":"759","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Response of a Benthic Sargassum Population to Increased Temperatures: Decline in Non-Photochemical Quenching of Chlorophyll a Fluorescence (NPQ) Precedes That of Maximum Quantum Yield of PSII"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4042-951X","authenticated-orcid":false,"given":"Ricardo M.","family":"Chaloub","sequence":"first","affiliation":[{"name":"Department of Biochemistry, Institute of Chemistry, Federal University of Rio de Janeiro, Rio de Janeiro 21941-909, Brazil"}]},{"given":"Rodrigo Mariath V.","family":"da Costa","sequence":"additional","affiliation":[{"name":"Research Institute Botanical Garden of Rio de Janeiro, Rio de Janeiro 22460-030, Brazil"},{"name":"Santa \u00darsula University, Rio de Janeiro 22231-040, Brazil"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7211-1661","authenticated-orcid":false,"given":"Jo\u00e3o","family":"Silva","sequence":"additional","affiliation":[{"name":"Centre of Marine Sciences (CCMAR), University of Algarve, 8005-139 Faro, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3306-0862","authenticated-orcid":false,"given":"Cristina A. G.","family":"Nassar","sequence":"additional","affiliation":[{"name":"Department of Botany, Institute of Biology, Federal University of Rio de Janeiro, Rio de Janeiro 21941-902, Brazil"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5662-8815","authenticated-orcid":false,"given":"Fernanda","family":"Reinert","sequence":"additional","affiliation":[{"name":"Department of Botany, Institute of Biology, Federal University of Rio de Janeiro, Rio de Janeiro 21941-902, Brazil"}]},{"given":"Maria Teresa M.","family":"Sz\u00e9chy","sequence":"additional","affiliation":[{"name":"Department of Botany, Institute of Biology, Federal University of Rio de Janeiro, Rio de Janeiro 21941-902, Brazil"}]}],"member":"1968","published-online":{"date-parts":[[2025,3,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"300","DOI":"10.1111\/jpy.12945","article-title":"Historical biogeography of the widespread macroalga Sargassum (Fucales, Phaeophyceae)","volume":"56","author":"Yip","year":"2020","journal-title":"J. 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