Growth Rate in Cultured Crustose Coralline Algae of the Genus Phymatolithon and Sporolithon From Taiwan

Coastal algal reef ecosystems, which are formed by the skeletal carbonate of crustose coralline algae (CCA), provide vital habitats for a diverse range of marine organisms and serve as valuable archives of long-term environmental data. Despite the importance of these reef ecosystems, there is currently a lack of available information regarding the accretion rates of CCA in subtropical intertidal zones in the Taoyuan algal reef. We measured the vertical accretion and horizontal growth of CCA cultured in two aquaculture tanks over a 9-month period. The vertical accretion and horizontal growth rate of CCA was approximately 0.29–0.43 and 5.5 μm·day⁻¹ (the extrapolated annual value is equivalent to 0.11–0.16 and 2.0 mm·year⁻¹, respectively). Newly colonized CCA had faster horizontal growth of approximately 110 μm·day⁻¹ (equivalent to 40.2 mm·year⁻¹). These results highlight the slow and gradual process of algal reef ecosystem formation in the subtropical intertidal zones. The CCA had a faster lateral growth rate as seen in the newly settled CCA. These findings contribute to our understanding of the overall growth dynamics of CCA.