Heterozostera nigricaulis from the south-East Pacific coast of Chile: First insights into its physiology and growth

Abstract

A short stretch (27°S and 30°S) along the coast of Chile is habitat for the seagrass Heterozostera nigricaulis. The seagrass is classified as endangered and grows only clonally, but there are no data on its physiology and growth. However, this information is important to gain insights into its acclimation potential and how disturbances may affect them. We therefore studied H. nigricaulis at 27° and 30°S, and determined their growth and physiology among seasons and depths over one year. Biomass was higher at 27° than at 30°S, and was always higher in summer than in autumn and winter. Increased photosynthesis supported growth in summer, and in winter carbonic anhydrase activity was in place to maintain these evergreen meadows. Our results suggest that these seagrass meadows are adapted to local conditions, which, together with their asexual reproduction, could make them more vulnerable to disturbance. Therefore, our results serve as a basis for future studies on seagrass growth dynamics, and are important for protection and management plans.

Keywords: Chile; Depth; Environmental conditions; Growth; Heterozostera nigricaulis; Photosynthesis; Physiology; Seagrass.