11:00 AM - 1:00 PM
[ACG40-P05] Responses of eelgrass seed germination to experimental warming in northern Japan populations
Keywords:Seagrass, Global warming, Laboratory experiment
The eelgrass Zostera marina is a widely distributed seagrass species in the northern hemisphere. This marine foundation species provides many ecosystem services such as habitat function for small fish and invertebrates, water purification, sediment stabilization, and carbon sequestration. Meanwhile, climate change including ocean warming impacts on coastal ecosystems including eelgrass beds. Influences of ocean warming on growth and physiology of adult eelgrass plants have been studied over the last three decades, while there is less information regarding the effect of temperature on its seed germination.
Here we conducted two experiments to assess the response of seed germination to different water temperatures targeting eelgrass populations in northern Japan. In July 2021, reproductive shoots with developing seeds were collected from Z. marina beds at Akkeshi and Muroran, Hokkaido prefecture. At Kamisu branch of Fisheries Technology Institute (FRA), we established three water temperature treatments (simulated for Hokkaido, Tohoku, and Tokyo Bay) using three 100-L tanks with closed cycle system. We set 57 eelgrass seeds for each treatment (n=57 for each) and started the experiment on October 14. During the experiment, water temperature of each treatment was adjusted to seasonal changes in water temperature at three model regions. At Marine Ecology Research Institute (MERI), we established two water temperature treatments (ambient seawater temperature and 3°C above ambient seawater temperature) using two 100-L tanks. On September 14, we set 100 eelgrass seeds from Akkeshi and Muroran in each treatment (n =80 from Akkeshi and n =20 from Muroran). We monitored seed germination as well as water temperature and salinity in both experiments.
We report tentative results of the two experiments. At FRA, we observed no germination (0.0 %) in the Hokkaido treatment (1.8–16.0℃) but found five germinations (8.8%) in the Tohoku (8.5–17.6℃) and four (7.0%) in the Tokyo Bay (10.3–19.5℃) until February 14, 2022. Meanwhile, at MERI, three (3.0%) and eight germinations (8.0%) were observed in the ambient (10.5–25.5℃) and warmed temperature (14.3–27.9℃) treatments, respectively, until this day.
Overall, our tentative results indicated warmed temperature can advance date of seed germination in the eelgrass populations of northern Japan. Global warming may, therefore, change phenology of eelgrass and have impacts on associated species.
Here we conducted two experiments to assess the response of seed germination to different water temperatures targeting eelgrass populations in northern Japan. In July 2021, reproductive shoots with developing seeds were collected from Z. marina beds at Akkeshi and Muroran, Hokkaido prefecture. At Kamisu branch of Fisheries Technology Institute (FRA), we established three water temperature treatments (simulated for Hokkaido, Tohoku, and Tokyo Bay) using three 100-L tanks with closed cycle system. We set 57 eelgrass seeds for each treatment (n=57 for each) and started the experiment on October 14. During the experiment, water temperature of each treatment was adjusted to seasonal changes in water temperature at three model regions. At Marine Ecology Research Institute (MERI), we established two water temperature treatments (ambient seawater temperature and 3°C above ambient seawater temperature) using two 100-L tanks. On September 14, we set 100 eelgrass seeds from Akkeshi and Muroran in each treatment (n =80 from Akkeshi and n =20 from Muroran). We monitored seed germination as well as water temperature and salinity in both experiments.
We report tentative results of the two experiments. At FRA, we observed no germination (0.0 %) in the Hokkaido treatment (1.8–16.0℃) but found five germinations (8.8%) in the Tohoku (8.5–17.6℃) and four (7.0%) in the Tokyo Bay (10.3–19.5℃) until February 14, 2022. Meanwhile, at MERI, three (3.0%) and eight germinations (8.0%) were observed in the ambient (10.5–25.5℃) and warmed temperature (14.3–27.9℃) treatments, respectively, until this day.
Overall, our tentative results indicated warmed temperature can advance date of seed germination in the eelgrass populations of northern Japan. Global warming may, therefore, change phenology of eelgrass and have impacts on associated species.