09 Mar 2021

09 Mar 2021

Review status: this preprint is currently under review for the journal BG.

An analysis of the macroalgal δ13C variability in the Gulf of California

Roberto Velázquez-Ochoa1, María Julia Ochoa-Izaguirre2, and Martín F. Soto-Jiménez3 Roberto Velázquez-Ochoa et al.
  • 1Posgrado en Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Unidad Académica Mazatlán, Mazatlán, Sinaloa 82040, México
  • 2Facultad de Ciencias del Mar, Universidad Autónoma de Sinaloa. Paseo Claussen s/n, Mazatlán, Sinaloa 82000, México
  • 3Unidad Académica Mazatlán, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México (UAM-ICMyL-UNAM), Mazatlán Sinaloa, 82040, México

Abstract. The C isotopic composition in macroalgae (δ13C) is highly variable, and its prediction is very complex relative to terrestrial plants. To contribute to the knowledge on the variations and determinants of δ13C-macroalgal, we analyzed a large stock of specimens varying in taxa and morphology and inhabiting shallow marine habitats from the Gulf of California (GC) featured by distinctive environmental conditions. A large δ13C variability (−34.61 ‰ to −2.19 ‰) was observed, mostly explained on the life form (taxonomy, morphology, and structural organization), and modulated by the interaction between habitat features and environmental conditions. The intertidal zone specimens had less negative δ13C values than in the subtidal zone. Except for pH, environmental conditions of the seawater do not contribute to the δ13C variability. Specimens of the same taxa showed δ13C similar patterns, to increase or decrease, with latitude (21º–30° N). δ13C-macroalgal provides information on the inorganic carbon source used for photosynthesis (CO2 diffusive entry vs HCO3 active uptake). Most species showed a δ13C belong into a range that indicates a mix of CO2 and HCO3 uptake; the HCO3 uptake by active transport is widespread among GC macroalgae. About 20–34 % of species showed the presence of carbon concentrating mechanism (CCM). Ochrophyta presented a high number of species with δ13C > −10 ‰, suggesting widespread HCO3 use by non-diffusive mechanisms. Few species belonging to Rhodophyta relied on CO2 diffusive entry (δ13C < −30 ‰) exclusively. δ13C provides useful information about the physiological and environmental status of macroalgae.

Roberto Velázquez-Ochoa et al.

Status: open (until 24 Apr 2021)

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  • RC1: 'Comment on bg-2021-50', Matheus C. Carvalho, 15 Mar 2021 reply

Roberto Velázquez-Ochoa et al.

Data sets

Analysis of the variation of stable carbon isotopes in macroalgae communities from shallow marine habitats in the Gulf of California ecoregion Soto-Jimenez, Maritn F., Velázquez-Ochoa, Roberto, and Ochoa Izaguirre, Maria Julia

Roberto Velázquez-Ochoa et al.


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Short summary
First interpretations of δ13C were in terrestrial plants and were used to identify carbon assimilation pathways (eg., C3, C4, and CAM plants). The classification does not apply in macroalgae, which are highly variable and very difficult to predict and interpret. In our study, a high δ13C variability was measured in macroalgae of the Gulf of California. Life forms but also modulated by the interaction between the habitat features and the environmental conditions explained the δ13C variability.