2002/03/19 by John A. Raven, Andrew M. Johnston, Andrew Johnston +15 · 3 citations
Earth and Planetary Sciences · Environmental Science · #Algae #Biology #Botany #Brown algae #Ecology #Ecophysiology #Fucales #Isotope Analysis in Ecology #Marine Biology and Ecology Research #Marine and coastal ecosystems #Photosynthesis #Red algae #Stable isotope ratio #Thallus #δ13C
paper · doi:10.1071/pp01201
crossref issued 2002/03/19 · crossref published 2002/03/19 · crossref published-print 2002/03/19 · openalex publication_date 2002/03/19 · crossref created 2002/09/16 · openalex created_date 2025/10/10 · crossref deposited 2025/11/18 · openalex updated_date 2026/07/02 · crossref indexed 2026/08/04
The literature, and previously unpublished data from the authors’ laboratories, shows that the δ13C of organic matter in marine macroalgae and seagrasses collected from the natural environment ranges from –3 to –35‰. While some marine macroalgae have δ13C values ranging over more than 10‰ within the thallus of an individual (some brown macroalgae), in other cases the range within a species collected over a very wide geographical range is only 5‰ (e.g. the red alga Plocamium cartilagineum which has values between –30 and –35‰). The organisms with very negative δ13C (lower than –30‰) are mainly subtidal red algae, with some intertidal red algae and a few green algae; those with very positive δ13C values (higher than –10‰) are mainly green macroalgae and seagrasses, with some red and brown macroalgae. The δ13C value correlates primarily with taxonomy and secondarily with ecology. None of the organisms with δ13C values lower than –30‰ have pyrenoids. Previous work showed a good correlation between δ13C values lower than –30‰ and the lack of CO2 concentrating mechanisms for several species of marine red algae. The extent to which the low δ13C values are confined to organisms with diffusive CO2 entry is discussed. Diffusive CO2 entry could also occur in organisms with higher δ13C values if diffusive conductance was relatively low. The photosynthesis of organisms with δ13C values more positive than –10‰ (i.e. more positive than the δ13C of CO2 in seawater) must involve HCO3- use.