Living at the margins – The response of deep-water seagrasses to light and temperature renders them susceptible to acute impacts

Chartrand, KM; Szabó, M; Sinutok, S; Rasheed, MA; Ralph, PJ

Living at the margins – The response of deep-water seagrasses to light and temperature renders them susceptible to acute impacts

Chartrand, KM

Szabó, M

Sinutok, S Rasheed, MA Ralph, PJ

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Publication Type:: Journal Article
Citation:: Marine Environmental Research, 2018, 136 pp. 126 - 138
Issue Date:: 2018-05-01

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Field	Value	Language
dc.contributor.author	Chartrand, KM https://orcid.org/0000-0002-0030-961X	en_US
dc.contributor.author	Szabó, M https://orcid.org/0000-0001-6235-2894	en_US
dc.contributor.author	Sinutok, S	en_US
dc.contributor.author	Rasheed, MA	en_US
dc.contributor.author	Ralph, PJ https://orcid.org/0000-0002-3103-7346	en_US
dc.date.available	2018-02-08	en_US
dc.date.issued	2018-05-01	en_US
dc.identifier.citation	Marine Environmental Research, 2018, 136 pp. 126 - 138	en_US
dc.identifier.issn	0141-1136	en_US
dc.identifier.uri	http://hdl.handle.net/10453/129606
dc.description.abstract	© 2018 Elsevier Ltd Seagrasses inhabit environments where light varies at different timescales, nonetheless are acutely sensitive to reductions in light beyond some conditional bounds. Two tropical deep-water seagrasses, Halophila decipiens and Halophila spinulosa, from the Great Barrier Reef were tested for their response to defined light and temperature regimes to identify their growth requirements and potential thresholds of mortality. Species were exposed to two light intensities, saturating (75 μmol photons m−2 s−1) and limiting (25 μmol photons m−2 s−1) light and two temperature treatments (26 °C and 30 °C) over a four-week period. Wavelength-specific parameters of PSII photochemistry were evaluated for seagrass leaves, as well as shoot density, gas exchange, and pigment content. Both species were sustained under saturating light levels (3.2 mol photons m−2 d−1) while limiting light led to decreased shoot density for H. decipiens and H. spinulosa after two and four weeks, respectively. Wavelength-specific photochemistry was also affected under light-limiting treatments for both species while the functional absorption cross section was highly conserved. Photoacclimation and physiological adjustments by either species was not adequate to compensate for reduced irradiance suggesting these plants reside at the margins of their functional limits. As such, relatively short periods of light attenuating events, like dredging or flood plumes, may be detrimental to deep-water seagrass populations.	en_US
dc.relation.ispartof	Marine Environmental Research	en_US
dc.relation.isbasedon	10.1016/j.marenvres.2018.02.006	en_US
dc.subject.classification	Marine Biology & Hydrobiology	en_US
dc.subject.mesh	Plant Leaves	en_US
dc.subject.mesh	Water	en_US
dc.subject.mesh	Ecosystem	en_US
dc.subject.mesh	Temperature	en_US
dc.subject.mesh	Sunlight	en_US
dc.subject.mesh	Seawater	en_US
dc.subject.mesh	Light	en_US
dc.subject.mesh	Aquatic Organisms	en_US
dc.title	Living at the margins – The response of deep-water seagrasses to light and temperature renders them susceptible to acute impacts	en_US
dc.type	Journal Article
utslib.citation.volume	136	en_US
utslib.for	0305 Organic Chemistry	en_US
utslib.for	0501 Ecological Applications	en_US
utslib.for	0607 Plant Biology	en_US
utslib.for	03 Chemical Sciences	en_US
utslib.for	05 Environmental Sciences	en_US
utslib.for	06 Biological Sciences	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Strength - C3 - Climate Change Cluster
pubs.organisational-group	/University of Technology Sydney/Students
utslib.copyright.status	closed_access
pubs.publication-status	Published	en_US
pubs.volume	136	en_US

Abstract:

© 2018 Elsevier Ltd Seagrasses inhabit environments where light varies at different timescales, nonetheless are acutely sensitive to reductions in light beyond some conditional bounds. Two tropical deep-water seagrasses, Halophila decipiens and Halophila spinulosa, from the Great Barrier Reef were tested for their response to defined light and temperature regimes to identify their growth requirements and potential thresholds of mortality. Species were exposed to two light intensities, saturating (75 μmol photons m−2 s−1) and limiting (25 μmol photons m−2 s−1) light and two temperature treatments (26 °C and 30 °C) over a four-week period. Wavelength-specific parameters of PSII photochemistry were evaluated for seagrass leaves, as well as shoot density, gas exchange, and pigment content. Both species were sustained under saturating light levels (3.2 mol photons m−2 d−1) while limiting light led to decreased shoot density for H. decipiens and H. spinulosa after two and four weeks, respectively. Wavelength-specific photochemistry was also affected under light-limiting treatments for both species while the functional absorption cross section was highly conserved. Photoacclimation and physiological adjustments by either species was not adequate to compensate for reduced irradiance suggesting these plants reside at the margins of their functional limits. As such, relatively short periods of light attenuating events, like dredging or flood plumes, may be detrimental to deep-water seagrass populations.

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http://hdl.handle.net/10453/129606