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Multi-driver climate change effects on SEAgrass METabolism: ecosystem implications

Periodic Reporting for period 1 - SEAMET (Multi-driver climate change effects on SEAgrass METabolism: ecosystem implications)

Reporting period: 2018-01-08 to 2020-01-07

Pressures linked to Global climate change (GCC) (ocean acidification (OA), warming and hipoxia) represent a major threat for marine ecosystems. The single and combined effects of GCC drivers is expected to alter the energetic costs of main metabolic routes, forcing trade-offs in organisms’ metabolism, with further impacts in the functioning of the whole ecosystem to which they belong. The consequences of GCC do not only affect organisms and functioning of marine systems but have also important repercussions for society and human well-being since the ecosystems services provided by marine systems may be also affected. To understand and determine realistic consequences of GCC we need to comprehend the impacts of multiple stressors on individuals, estimate the acclimation and adaptation capacity of organisms, and assess the repercussion of individual adjustments on the ecosystems functioning. SEAMET project addresses this major challenge in marine science by assessing if marine communities can survive under the multiple stressor future driven by GCC.

The aim of the project SEAMET was at exploring the physiological tolerance, metabolic adjustments and plasticity limits of marine benthic photoautotrophs to different GCC drivers, such as OA and global warming, to evaluate the potential of individuals for acclimation and adaptation to climate change and the implications for the whole community and ecosystem functioning.
To reach this global aim, SEAMET was structured to operate at three hierarchical levels, from supracellular to community. These levels coincide with the objectives and the three first work-packages (WP 1 to 3) described in the project. The net metabolic balance (NMB) was used as a functional trait to explore the scaling-up implications of individual adjustments on the functioning of the community, the ecosystem, and the carbon cycling using seagrasses as a main model species.

-Objective 1. WP1-Mechanistic bases of carbon-related physiology.
-Objective 2. WP2-Physiological plasticity, and tolerance limits of organisms to GCC drivers.
-Objective 3. WP3-Acclimation and adaptation potential of organisms and associated communities to GCC.
-Objective 4. WP4-Dissemination of results and outreach.

SEAMET has validated the use of the Net Metabolic Balance as a trait suitable for estimating the metabolic status of organisms and quantify the effects of GCC drivers on organism’ physiology and carbon metabolism. Globally, SEAMET results pointed to large metabolic plasticity of the seagrass (i.e. Zostera marina, Cymodocea nodosa and Syringodium isoetifolium) and macroalgae (i.e. Caulerpa polifera) species studied.
Objectives and Work packages (WP)

Objective 1. WP1-Mechanistic bases of carbon-related physiology.
This objective was approached in laboratory experiments.
Fluorescence and Photosynthesis vs Irradiance curves, Gas Chromatography-Mass Spectrometer, and High-resolution x-ray computed tomography imaging techniques were successfully applied. Photochemical potential for inorganic carbon assimilation, lipidic biomarkers related with carbon metabolism and high-resolution microstructural images were measured.
Plants of Z. marina recurrently exposed to Ci-enriched seawater showed a slight but consistent higher potential for light use and photochemistry, leading to a higher potential in Ci use. Lipidic biomarkers related with carbon metabolism were identified but the organic carbon availability did not seem to affect the speciation neither the concentration of lipidic compounds in seagrass leaves. The high-resolution imaging data did not reveal the existence of any carbonate structure or internal carbonate deposits accumulation within the leaves of the seagrass S. isoetifolium.

Objective 2. WP2-Physiological plasticity, and tolerance limits of organisms to GCC drivers.
Two mesocosms experiments were conducted to identify the physiological plasticity and metabolic tipping points of the seagrass Z. marina to climate change drivers (warming and OA) and its combination. Another mesocosms experiment was implemented to evaluate the physiological plasticity of the macroalgae C. prolifera to rising temperature.
Preliminary results revealed a large physiological plasticity, in terms of net metabolic balance, on both Z. marina and C. prolifera. Z. marina growing in mid-high latitudes tolerates temperature increases up to 20 ºC but physiological threshold seems to be set between 20-25ºC, the temperature tolerance threshold for C. prolifera growing in temperate latitudes seems to be set beyond 30ºC.

Objective 3. WP3-Acclimation and adaptation potential of organisms and associated communities to GCC.
In situ by measurements and comparison on the net metabolic balance of different seagrass meadows along latitudinal gradients and in up-welling areas were conducted as a proxy of GCC drivers (warming and OA).
A large physiological plasticity suggests large acclimation potential in the seagrass Z. marina. Results revealed a significant dependence of the net metabolic balance with temperature. Global warming can benefit the metabolism of meadows growing in higher latitudes. Slight physiological improvements in energy use were detected in plants growing in areas exposed to carbon-enriched seawater (up-welling areas).

Objective 4. WP4-Dissemination of results and outreach.
Communications in international conferences and meetings, academic seminars, teaching, articles in social media (Twitter), newspapers and journals and public engagement activities have been delivered along the execution of the project and will continue in the near future.
(A detailed list in the technical report)

Scientific publications:
-Olivé et al. 2019. SEAMAY-un projet collaboratif pour étudier les prairies d’herbiers de Mayotte. “La Feuille Marine Actualités 2016-2018 des herbiers d'outre-mer,” 3, 26-27.
In preparation:
6 papers are in preparation to be published in high-impact peer-reviewed scientific journals

Invited speaker in international meetings
-Keynote presentation. 68th Annual Meeting of the British Phycological Society. 2020. UK.
-Invited presentation. 7th ENVRI week, EU-ENVRIplus project. 2018. Latvia.

Communications in international Conferences:
-Olivé et al. Carbon metabolism and blue carbon sequestration potential of seagrass beds across Scotland. SAGES’19 conference. 2019. UK.
-Olivé et al. Seagrass contribution to productivity and community biogeochemistry in Reunion Island (West Indian ocean). 25th CERF conference. 2019. USA.

Invited participation in international workshops and meetings
-1st GOA-ON North East Atlantic Hub Meeting. 2019. London.
-EuroMarine Workshop “Trait-based approach to seagrass ecosystems”. 2018. Italy.

Academic teaching (undergraduate and postgraduate level):
-International Master in Marine Biological Resources (IMBRSea) Summer School. 2019
-Case study Challenge Series. BSc Marine Biology. School of Aquatic and Fishery Sciences, University of Washington. 2018.

Invited academic seminars:
-Olivé I. Instituto Investigaciones Oceanológicas (IIO-UABC). 2019. Mexico.
-Olivé I. Scottish Universities Environmental Research Centre (SUERC). 2018. UK.

Engagement activities:
-Discovering women in science. Bangs goes the borders Science Festival. 2019.
-Building women in science. Glasgow Science Center. 2019.
Image of seagrass meadow and its associated community by I. Olive