Seagrass and macroalgal community dynamics and performance under environmental change
Organismic Interactions, Chemical Ecology and Microbiomes of Plant Systems
Plant Physiology
Final Report Abstract
This project aimed to fill in the knowledge gap of tropical seagrass community dynamics and performance under changing environments using a trait-based approach by determining temporal and spatial distribution and abundance of the highly diverse tropical seagrass communities in relation to changing environmental conditions and by examining biological, physiological, and chemical response traits of tropical seagrasses and macroalgae to abiotic and biotic stressors. Through field studies we assessed tropical seagrass community structure under varying environmental conditions within the Indopacific seagrass bioregion, Zanzibar Tanzania. We found various drivers to be important in shaping seagrass and macroalgal community structure, including top-down control by sea urchin grazing and bottom-up controls of nutrient enrichment and light limitation. Additionally we examined other direct impacts such as seaweed farming on seagrass and macroalgal community dynamics. From field surveys and experiments, we determined species-specific differences in seagrass trait responses which played a role in the composition and abundance of species under various stressors. We further tested abiotic stressors in the laboratory in short-term individual experiments and longerterm community mesocosm experiments. As eutrophication was one of the main drivers of changes in community structure, we focused on species-specific strategies of coping with increased nutrient inputs in combination with increasing temperature. We also tested effects of climate change alone, through combinations of increased temperature and CO2 conditions. We showed significant differences in trait responses of seagrasses to nutrients and temperature among persistent and opportunistic species such as in nutrient uptake, assimilation, and storage as well as in photosynthetic response and carbon storage and metabolism. These trait responses allow us to better understand which species may be better adapted to what conditions and suggests that inter-specific competition may be high, particularly under intermediate nutrient levels. Overall, we found that tropical seagrass ecosystems suffer similar stressors to temperate systems, with local eutrophication being a major concern to their overall health. Surprisingly, we found less impact of moderate temperature increase, suggesting that most tropical seagrasses may be more temperature tolerant. However, in combination of nutrients and temperature increase, community dynamics are much more variable and rapidly changing which may drive internal feedbacks within the system from other system components. Responses to CO2 increase, which may be expected to favor seagrasses, seemed to have minor effects alone on seagrass response, but showed some interactive effects with temperature. Through all field and laboratory studies, we collected a vast amount of trait data which we only have begun to explore. To start this process, we had the timely opportunity to work with other European seagrass and plant researchers to develop a trait-based framework for seagrass ecosystems. This framework is based on the integration of concepts developed from the terrestrial plant literature adapted to the marine environment. Through this framework, we believe trait-based research in seagrasses will develop rapidly, which until now has surprisingly not been applied. Using this framework will allow us to better predict how seagrasses ecosystems will respond to environmental change and how these changes will in turn affect ecosystem function.
Publications
- 2016. Feeding behaviour of the sea urchin Tripneustes gratilla in relation to a seagrass overgrazing event in Zanzibar Archipelago, Tanzania. International Seaweed Biology Workshop, Wales
Moreira-Saporiti A et al.
- 2016. Nitrate reductase and glutamine synthetase activity of Cymodocea serrulata (R.Brown), under varying concentrations and sources of nitrogen. International Seaweed Biology Workshop, Wales
Saavedra-Hortua D et al.
- 2016. Nitrogen uptake, transport and allocation in tropical seagrasses under different nitrogen sources. International Seaweed Biology Workshop
Viana I et al.
- 2018. Seagrass community- level controls over organic carbon storage are constrained by geophysical attributes within meadows of Zanzibar, Tanzania. Biogeosciences 15: 4609-4626
Belshe EF, Hoeijmakers D, Herran N, Mtolera M, and Teichberg M
(See online at https://doi.org/10.5194/bg-15-4609-2018) - 2019. Different strategies of nitrogen acquisition in two tropical seagrasses under nitrogen enrichment. New Phytologist, 6 May 2019
Viana IG, Arturo Saavedra Hortua D, Mtolera M, Teichberg M
(See online at https://doi.org/10.1111/nph.15885) - 2020. Morphological and physiological responses of Enhalus acoroides seedlings under varying temperature and nutrient treatment. Frontiers of Marine Science, 15 May 2020
Artika SR, Ambo-Rappe R, Teichberg M, Saporiti AM, Viana IG
(See online at https://doi.org/10.3389/fmars.2020.00325) - 2020. Species-specific trait responses of three tropical seagrasses to multiple stressors: the case of increasing temperature and nutrient enrichment. Frontiers of Plant Science, 05 November 2020
Viana I, Saporiti AM, Teichberg M.
(See online at https://doi.org/10.3389/fpls.2020.571363) - 2021. Rising temperature is a more important driver than increasing carbon dioxide concentrations in the trait responses of Enhalus acoroides seedlings. Applied Sciences 11, 2370
Artika SR, Ambo-Rappe R, Teichberg M, Samawi MF, Saporiti AM, Viana IG
(See online at https://doi.org/10.3390/app11062730) - 2021. Seaweed farming pressure affects seagrass and benthic macroalgae dynamics in Chwaka Bay (Zanzibar, Tanzania). Regional Environmental Change 21, 11 (2021)
Moriera-Saporiti A, Hoeijmakers D, Msuya F, Reuter H, Teichberg M.
(See online at https://doi.org/10.1007/s10113-020-01742-2)
