High heat tolerance and thermal safety margins in mangroves from the southwestern coast of India

• Published in: The Science of the total environment 2024-12, Vol.954, p.176366, Article 176366
• Main Authors: Naseef, Abdulla, Javad, Akhil, Kausal, A.K., Barua, Deepak, Ashtamoorthy, Sreejith Kalpuzha
• Format: Article
• Language: English
• Subjects: Avicennia marina; Bruguiera gymnorhiza; Climate change; coasts; decline; ecosystems; environment; Global warming; heat tolerance; High temperature tolerance; India; Leaf temperature; Leaf traits; leaves; photosynthesis; species; woody plants
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2024.176366

Mangroves are key components of productive ecosystems that provide a multitude of ecosystem goods and services. How these species will respond to future climates with more frequent and severe extreme temperatures has not received much attention. To understand how vulnerable mangroves are to future warming, we quantified photosynthetic heat tolerance and estimated thermal safety margins for thirteen mangrove species from the southwestern Indian coast. We quantified heat tolerance as temperatures that resulted in a 5 % (T5) and 50 % (T50) decline in photosystem II function, and thermal safety margins (TSM) as the difference between T50 and maximum leaf temperatures. T50 ranged from 48.9 °C in Avicennia Marina to 55.3 °C in Bruguiera gymnorhiza, with a mean of 53.3 °C for the thirteen species. Heat tolerance was higher for species with bigger leaves which experience higher leaf temperatures, but was not related to the other leaf traits examined. Heat tolerance was exceptionally high in these mangroves compared to other woody species. With their high tolerance and large safety margins these mangroves may be relatively less vulnerable to future climates with higher temperatures. [Display omitted] •Mangroves from the southwestern coast of India had exceptionally high heat tolerance that is higher than other woody species from across the globe.•Estimates of maximum leaf temperatures were higher than air temperatures, but lower than heat tolerance, indicating large thermal safety margins.•Heat tolerance was higher in species with bigger leaves that experience higher leaf temperatures.•With high tolerance and large safety margins these mangroves may be relatively less vulnerable to increased temperatures in future climates.