Halocarbon emissions by selected tropical seaweeds exposed to different temperatures
Document Type
Article
Publication Date
10-1-2021
Abstract
Four tropical seaweeds, Gracilaria manilaensis Yamamoto & Trono, Ulva reticulata Forsskal, Kappaphycus alvarezii (Doty) L.M.Liao and Turbinaria conoides (J.Agardh) Kutzing, collected from various habitats throughout Malaysia, were subjected to temperatures of 40, 35, 30, 25 and 20 degrees C in the laboratory. An exposure range of 21-38 degrees C is reported for Malaysian waters. The effect of the temperature exposures on the halocarbon emissions of the seaweeds were determined 4 and 28 h after treatment. The emission rates for a suite of six halocarbons commonly emitted by seaweeds, bromoform (CHBr3), dibromomethane (CH2Br2), diiodomethane (CH2I2), iodomethane (CH3I), dibromochloromethane (CHBr2Cl) and dichlorobromomethane (CHBrCl2), were measured using a cryogenic purge-and-trap sample preparation system coupled to a gas chromatography-mass spectrometry. The emission rate of CHBr3 was the highest of the six halocarbons for all the seaweeds under all the temperatures tested, followed by CH2Br2, and CH2I2. The emission rates were affected by temperature change and exposure duration, but overall responses were unique to each seaweed species. Larger decreases in the emissions of CHBr3, CH2Br2, CH2I2 and CHBr2Cl were found for K. alvarezii and T. conoides after 4 h at 40 degrees C. In both cases there was a 90% (p < 0.05) reduction in the Fv/Fm value suggesting that photosynthetic actitivity was severely compromised. After a 28 h exposure period, strong negative correlations (r = -0.69 to -0.95; p < 0.01) were observed between temperature and the emission of CHBr3, CH2Br2 and CH2I2 for U. reticulata, K. alvarezii and T. conoides. This suggests a potential decrease in the halocarbon emissions from these tropical seaweeds, especially where the temperature increase is a prolonged event. Strong correlations were also seen between seaweed chlorophyll and carotenoid pigment contents and the emission rates for CHBr3, CH2Br2 and CH2I2 (r = 0.48 to 0.96 and -0.49 to -0.96; p < 0.05). These results suggest that the regulation of halocarbon production versus reactive oxygen species production in seaweeds is an area worthy of further exploration.
Keywords
Gracilaria manilaensis (Gracilariaceae), Ulva, reticulata (Ulvaceae), Kappaphycus alvarezii (Solieriaceae), Turbinaria conoides (Sargassaceae), Tropical seaweeds, Climate change, Temperature, Halocarbon emissions, Bromoform
Divisions
ocean
Funders
Ministry of Higher Education Malaysia under the Higher Institution Centre of Excellence (HICoE) Programme (Phase II) [IOES-2014F],University of Malaya Research University Fund [RU009J-2020],University of Malaya Grand Challenge Fund [GC002B-15SBS],Postgraduate Research Grant [PG300-2016A]
Publication Title
Phytochemistry
Volume
190
Publisher
Elsevier
Publisher Location
THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND