Variability in growth and tissue composition (CNP, natural isotopes) of the three morphotypes of holopelagic Sargassum

Variability in growth and tissue composition (CNP, natural isotopes) of the three morphotypes of holopelagic Sargassum

Holopelagic Sargassum blooms in the tropical North Atlantic since 2011 are composed of two species, Sargassum natans and S. fluitans, and three morphotypes: S. natans VIII, S. natans I and S. fluitans III. The distinct morphology and the variations in space and time of the proportion of these three...

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Bibliographic Details
Published in:Aquatic botany Vol. 187; p. 103644
Main Authors: Changeux, T., Berline, L., Podlejski, W., Guillot, T., Stiger-Pouvreau, V., Connan, S., Thibaut, T.
Format: Journal Article
Language:English
Published: Elsevier B.V 01-07-2023
Elsevier
Subjects:
Algal bloom
Botanics
Brown macroalgae
Carbon
Earth Sciences
In-situ culture
Life Sciences
Nitrogen
Oceanography
Phosphorus
Sargasso
Sciences of the Universe
Seaweed
Vegetal Biology
Seaweed
Brown macroalgae
Algal bloom
In-situ culture
Phosphorus
Nitrogen
Carbon
Sargasso
Holopelagic Sargassum
Growth
Nutrient content
Morphotypes
Natural isotopes
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Summary:Holopelagic Sargassum blooms in the tropical North Atlantic since 2011 are composed of two species, Sargassum natans and S. fluitans, and three morphotypes: S. natans VIII, S. natans I and S. fluitans III. The distinct morphology and the variations in space and time of the proportion of these three morphotypes suggest that they may have different physiology. For the first time, we have quantified the growth rates of these three morphotypes through in situ 9-day experiments on the coast of Martinique Island (French West Indies). Despite the non-optimal conditions for growth for these pelagic species and the short time of the experiment, we have observed that Sargassum fluitans III was growing faster (approximately twice as fast) than S. natans VIII and S. natans I. Sargassum natans I exhibited the slowest growth. The differences in tissue composition (CNP and CN natural isotopes) of morphotypes point to a greater benefit for S. fluitans III from the coastal localization of our experiment than for the two S. natans morphotypes, and suggest that S. natans I had achieved its last growth further offshore before our experiment. These contrasting growth performances are consistent with the dominance of S. fluitans III in recent observations in the Caribbean region and along the path from the Sargassum belt. This also makes this last morphotype the best candidate for cultivation. Making the distinction between the growth performances of morphotypes may improve the current predictive models about dispersal of these species. •Sargassum fluitans III growth rate is the highest.•Sargassum natans I growth rate is the lowest.•Tissue composition differs between morphotypes.
ISSN:0304-3770
1879-1522
DOI:10.1016/j.aquabot.2023.103644