Global and local impacts on Atlantic RHODOlith beds: Implications for estimates of blue CARbon ecosystem services

Project Information

RHODOCAR

Grant agreement ID: 844703

DOI

10.3030/844703

Project closed

EC signature date 17 April 2019

Start date 1 June 2019

End date 31 May 2021

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 147 815,04

EU contribution

€ 147 815,04

Coordinated by

CENTRO DE CIENCIAS DO MAR DO ALGARVE
Portugal

Periodic Reporting for period 1 - RHODOCAR (Global and local impacts on Atlantic RHODOlith beds: Implications for estimates of blue CARbon ecosystem services)

Reporting period: 2019-06-01 to 2021-05-31

Summary of the context and overall objectives of the project

Rhodolith beds are recognized internationally as a unique ecosystem - built by free-living coralline algae - providing substrate and habitat for numerous algae and sessile invertebrates. In addition, their ability to calcify and their high abundance and biomass makes rhodoliths major carbonate producers. Recent empirical estimations suggest that the marine carbonate deposits generated by these organisms represent a total potential carbon sink of 0.4 x 109 t C yr-1. Hence, giving the increasing role of marine ecosystems in removal and storage of carbon (blue carbon), rhodolith beds may represent a not yet considered significant carbon store.
The EU-funded RHODOCAR project addresses this question by determining the carbon fluxes associated to rhodolith and rhodolith-bed community metabolism, carbonate production and storage, as well as their responses to global and local stressors. This information allows assessing the importance of rhodolith beds as natural carbon sinks, thus, help ascertain whether these ecosystems meet the requirements to be integrated into climate mitigation policy, and will further allow quantifying the effects of global climate change on their carbon sequestration and storage ability. In addition, it will help recognizing potential interactions between global and local stressors and hence, aid in the development of effective local conservation and management strategies.
RHODOCAR uses an integrative physiological approach to determine and scale-up individual and community productivity and the responses to global and local stressors to define the implications for ecosystem functioning and services. This approach includes a combination of laboratory, multi-factorial mesocosm and in situ experimentation, thus covering a wide range of complexity (cellular-organism-community). In addition, the project is designed to operate at a wide geographical scale, including rhodolith beds from different latitudes.
To accomplish the above mentioned general aim, the project is divided into the following objectives that also represent the different work packages:
WP1) Mechanistic understanding of rhodolith calcification - Determining the mechanistics and the degree of control the rhodoliths exhibit over the calcification process.

WP2) Impacts of multiple global and local stressors - Determining the effects of individual and combined climate-change related and local stressors and their potential interactions on key physiological processes of rhodolith species and assemblages.

WP3) Carbon sequestration and storage potential of rhodolith communities: Implications for Blue Carbon - Determining rhodolith bed-community metabolic rates, carbon flux and storage and modelling potential changes due to global and local impacts.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Work Package 1: Mechanistic understanding of rhodolith calcification
Short-term laboratory experiments were used to (a) assess the link between photosynthesis and calcification in different rhodolith species, (b) determine carbon-use strategies and physiological pathways to identify potential species-specific differences, and (c) assess the importance of rhodolith morphology on calcification and ocean acidification responses.
Results: Rhodolith species vary in their biological control of the calcification mechanism due to species-specific and morphological differences, which indicate the importance of rhodolith-community composition regarding the impacts of environmental stressors (e.g. climate change)

Work Package 2: Impacts of multiple global and local stressors
The effects of the increasingly more frequent and intense heatwaves on a rhodolith bed in Southern Portugal were investigated through a mid-term mesocosm experiment (weeks), in which different temperature regimes were simulated. The location of the studied rhodolith bed is influenced by frequent inversions between upwelling and downwelling conditions and the associated strong and fast temperature decreases and increases, respectively, which also allowed determining the effects of recurrent thermal stress on rhodolith primary and carbonate production.
Results: Impacts of environmental changes, such as marine heatwaves, are mitigated in rhodolith beds in highly fluctuating environments, where the recurrent stress increases their resilience.

Work Package 3: Carbon sequestration and storage potential of rhodolith communities: Implications for Blue Carbon
Field campaigns at different locations were performed, combined with on-site laboratory measurements of collected rhodolith samples. The biomass of rhodoliths (living and dead) per rhodolith bed area was determined through field collections and these data sets were combined with laboratory measurements of primary and carbonate productivity of the living rhodoliths, carbonate production/dissolution measured in dead rhodoliths and environmental in-situ light data for the respective rhodolith bed. This budgeting approach allowed determining and comparing the daily productivity and associated carbon fluxes of rhodoliths per m2 of rhodolith bed among the different locations.
Results: Most studied rhodolith beds can act as carbon sinks, though the magnitude depends on rhodolith biomass, predominant rhodolith species and environmental conditions, such as light availability.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

In the short-term, RHODOCAR has yielded scientific publications and more results will be published in the near future and presented in international congresses and to a wider public.
Long-term, the project results will call attention to rhodolith beds as so far overlooked, but potentially important ecosystems with a capacity to act as natural carbon sinks and stores, essentially leading to increasing global efforts that will permit upscaling their role in the global carbon cycle across large spatial and temporal scales, which is currently hindered by almost non-existing knowledge of their current global extension and associated carbon pools and dynamics. This will allow for a more accurate global carbon budget, which in turn will have strong relevance for the development of adequate climate policies, such as the development of marine carbon markets in the Reducing Emissions from Deforestation and forest Degradation programs under the United Nations Framework for Climate Change Convention (UNFCCC). Furthermore, the project results regarding the impacts of global and local stressors generate information in-line with the mission and scientific challenge of the 2030 Agenda (Goal 13, 14) and will allow the development of strategies to locally and regionally reduce marine pollution activities and to avoid adverse impacts (interaction with global stressors), thus increasing ecosystem resilience.

Shallow rhodolith bed in Canary Islands