Resumen de Growth responses of the intertidal seagrass Zostera japonica to manipulated sea level rise conditions
Seung Hyeon Kim, Woo J. Kim, Young Kim, Kun-Seop Lee
Although most seagrasses inhabit subtidal areas, a few species occur in the intertidal zone. The seagrass, Zostera japonica Asch. & Graebn., is an intertidal seagrass species, and thus this species may be vulnerable to environmental changes associated with sea level rise due to climate change. We examined the effects of continuous submergence conditions, which might be caused by sea level rise, on the growth of the intertidal seagrass, Z. japonica. In the present study, submerged conditions were generated in a Z. japonica meadow in the intertidal zone using transparent cylindrical cores, and the growth responses to the inundation conditions were examined. Daily photon flux density and temperature were not significantly different between the manipulated submerged and the control intertidal conditions during the experimental period. Increases in shoot height, biomass, and leaf productivity were among the acclimatory responses of Z. japonica to the inundation conditions. Shoot density, however, decreased rapidly in the submerged conditions as a result of the self-shading induced by taller and larger shoot sizes. Thus, prolonged inundation, which would be induced by a rise in sea level, had both positive and negative effects on the growth of the intertidal seagrass, Z. japonica, which exhibited plasticity at the individual and population levels. According to the results of our study, the restricted distribution of Z. japonica in the intertidal zone may not be a consequence of tidal inundation stress in the subtidal zone.
