Ye Rim Kim1, Young Jun Song1, Hee Yeon Park1, Yeo Jin Yoon2, Ju-Hyoung Kim2, and Young Sik Kim1
1Department of Marine Biology, Kunsan National University, Gunsan 54150, South Korea
2Department of Aquaculture and Aquatic Science, Kunsan National University, Gunsan 54150, South Korea
Recently, foliose macroalgal communities in temperate coastal ecosystems have been experiencing extreme community succession due to climate and environmental changes. A representative example is the barren habitat, which is affected by top-down and bottom-up control, with nothing but denuded substrate remaining. In barren habitats, as the canopy-forming algae disappear, coralline algae are exposed to various light environments during the phase shift from macroalgal habitats to barren habitats. Thus, we hypothesized that a rapid increase in light intensity due to the disappearance of canopy-forming algae induces photodamage of crustose coralline algae (CCA). To test this hypothesis, an indoor mesocosm experiment was conducted with various light intensities (20, 60, 120, and 250 μmol photons m-2 s-1) for 30 days. The growth of the marginal encrusting area and the photosynthesis traits showed that CCA are acclimated to a limited-light environment. Conversely, the encrusting area was reduced and bleaching of CCA was also identified under higher light levels. These results indicate that CCA co-inhabit with canopy-forming algae in environments with sufficient light exposure to support growth and photosynthesis due to the shade provided by the canopy. However, if the canopy-forming algae disappear, CCA will also disappear due to extreme light stress