MEPS 381:71-82 (2009)  -  DOI: https://doi.org/10.3354/meps07948

Carbon stable isotope discrimination: a possible growth index for the kelp Undaria pinnatifida

Matheus Carvalho de Carvalho*, Ken-Ichi Hayashizaki, Hisao Ogawa

Kitasato University, School of Marine Biosciences, 160-4 Utou, Okkirai, Sanriku-cho, Ofunato, Iwate 022-0101, Japan

ABSTRACT: Undaria pinnatifida sporophytes were grown in a marine bay under differing culture conditions in order to obtain individuals with different growth rates. Carbon stable isotope compositions of seawater and cultured algae were measured to calculate carbon stable isotope discrimination due to carbon assimilation (Δ) by the thalli. High and significant correlations were found between growth rates (absolute in length, absolute in weight, or relative in weight) and Δ, which suggests that growth rate was the most important factor determining Δ. The correlation between Δ and relative growth rate in weight was especially good, following the formula: Δ = 28.6 – 1.4RGR (r = –0.97), in which RGR is the relative growth rate in weight (% d–1). This very good correlation, if confirmed for other instances, would allow Δ to be used as a growth index for the species. Results also suggested that HCO3 uptake may be the main mechanism of inorganic carbon assimilation for the studied species.


KEY WORDS: δ13C · Seaweed · Primary production · Field experiment · Growth analysis


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Cite this article as: Carvalho MC, Hayashizaki K, Ogawa H (2009) Carbon stable isotope discrimination: a possible growth index for the kelp Undaria pinnatifida. Mar Ecol Prog Ser 381:71-82. https://doi.org/10.3354/meps07948

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