Projecting impacts of ocean warming on seagrass distribution in the Central Indo-West Pacific region
Ramadhan, M.I.A.K. (2021). Projecting impacts of ocean warming on seagrass distribution in the Central Indo-West Pacific region. MSc Thesis. Universiteit Antwerpen/Ghent University/Vrije Universiteit Brussel: Antwerpen, Gent, Brussel. 57 pp.
The temperature of the ocean has been continuously rising to a level not seen for a million years ago, with potential negative impacts on marine ecosystem. Seagrasses are key primary producers and ecosystem engineers which provide significant ecosystem services in shallow water communities. It is predicted that ocean warming will lead to seagrass distribution shift and habitat loss. In this study, we assessed factors affecting habitat distribution of tropical seagrass species and forecasted the impact of future ocean warming on the species. We used species distribution modelling (SDM) to project the future distributions of the seagrasses under 3 warming scenarios in 2050 and 2100. We run the SDM based on occurrence data of five seagrass species: Thalassia hemprichii, Enhalus acoroides, Cymodocea serrulata, Halodule uninervis and Halophila ovalis. These species are broadly distributed in the Central Indo-West Pacific and represent a variety of seagrass ecological traits. Our study shows that inclusion of photosynthetic rate affects the percentage number on both habitat gain and losses for the selected seagrass species. Under different ocean warming scenarios, seagrasses shown habitat losses ranging from 6% to more than 31%, and habitat gain less than 3% in 2050 under 3 different scenarios. In 2100, habitat loss ranges from 3% up to more than 33%, while habitat gain was not more than 3.25%. Increase ocean temperature favored small seagrass species with rapid recovery rate (Halophila ovalis) more than seagrass with large size with long life span (Thalassia hemprichii and Enhalus acoroides). Distributional shifts shown to be polar – ward where the losses were projected to occur along the tropical region. Cymodocea serrulata has the lowest habitat loss projected, in comparison with other species, displaying its potential as a potential species for transplantation. Halophila ovalis has the highest habitat gain, potentially showing its invasive capacity in the area.