Interactive Effects of Increased Temperature and pCO sub(2) Concentration on the Growth of a Brown Algae Ecklonia cava in the Sporophyte and Gametophyte Stages

• Published in: Ocean and polar research Vol. 37; no. 3; pp. 201 - 209
• Main Authors: Oh, Ji Chul, Yu, Ok Hwan, Choi, Han Gil
• Format: Journal Article
• Language: Korean
• Published: 01.09.2015
• Subjects: Ecklonia; Ecklonia cava; Laminariales; Phaeophyta
• ISSN: 1598-141X; 2234-7313
• DOI: 10.4217/OPR.2015.37.3.201

To examine the effects of increased CO sub(2) concentration and seawater temperature on the photosynthesis and growth of forest forming Ecklonia cava (Laminariales, Phaeophyta), sporophytic discs and gametophytes were cultured under three pCO sub(2) concentrations (380, 750, 1000 ppm), four temperatures (5, 10, 15, 20[degrees]C for sporophytes; 10, 15, 20, 25[degrees]C for gametophytes), and two irradiance levels (40, 80 mu mol photons m super(-2)s super(-1)) for 5 days. Photosynthetic parameter values (ETR sub(max), E sub(k), and alpha ) were generally higher as sporophytic discs were grown under low temperature and increased CO sub(2) concentration at 750 ppm. However, photosynthesis of Ecklonia sporophytes was severely inhibited under a combination of high temperature (20[degrees]C) and 1000 ppm CO sub(2) concentration at the two photon irradiance levels. The growth of gametophytes was maximal at the combination of 380 ppm (present seawater CO sub(2) concentration) and 25[degrees]C. Minimal growth of gametophytes occurred at enriched pCO sub(2) concentration levels (750, 1000 ppm) and high temperature of 25[degrees]C. The present results imply that climate change which is increasing seawater temperature and pCO sub(2) concentration might diminish Ecklonia cava kelp beds because of a reduction in recruitments caused by the growth inhibition of gametophytes at high pCO sub(2) concentration. In addition, the effects of increased temperature and pCO sub(2) concentration were different between generations - revealing an enhancement in the photosynthesis of sporophytes and a reduction in the growth of gametophytes.