The untapped potential of Poseidon grass in Greece as a hotspot for climate change mitigation

Author Identifier (ORCID)

Paul S. Lavery: https://orcid.org/0000-0001-5162-273X

Oscar Serrano: https://orcid.org/0000-0002-5973-0046

Abstract

This study aimed to provide baseline information on blue carbon storage in seagrass (Posidonia oceanica) meadows of Greece. To achieve this, the natural variability of organic carbon (Corg) stocks at the top meter of sediment and accumulation rates over the last 500 years was assessed in 42 sites across four regions of the Aegean Sea: the Saronikos Gulf, the Cyclades and Dodecanese Archipelagos and Crete Island. The mean Corg stock was 111 ± 5 Mg ha−1, with 0.25 ± 0.02 Mg ha−1 yr−1 across sites. Results from the Generalised Additive Model (GAM) indicated that silt/clay content, organic to inorganic carbon ratio and stable carbon isotope ratio (δ13C) had positive effects on the stock, whereas water depth had a negative effect. The sampling region also had a significant effect, with the Cyclades and Dodecanese Archipelagos supporting higher carbon storage. By upscaling the stocks to the total P. oceanica area studied, top-meter sediment stocks were estimated at 6,633,480 Mg Corg, equivalent to 34% of Greece’s Greenhouse Gas (GHG) emissions in 2023. Projected seagrass losses could result in potential emissions of 61 kt CO2 eq. yr−1, while management actions that prevent these losses could achieve up to 13% of the national 2030 target of 1,154 kt CO2 eq. in additional removals. Based on these findings, net removals from P. oceanica meadows are projected to contribute approximately 100–200 kt CO2eq. annually to the GHG Inventory. While further research is needed to refine national estimates, these results provide strong justification for integrating removals from management interventions in P. oceanica meadows into national GHG Inventories, where their inclusion could meaningfully support national climate mitigation goals.

Document Type

Journal Article

Date of Publication

3-1-2026

Volume

26

Issue

1

Publication Title

Regional Environmental Change

Publisher

Springer

School

Centre for Marine Ecosystems Research / School of Science

Funders

ARC / PID2020-117639GB-100 (funded by MCIN/AEI) / MEDCHANGE (funded by the Agencia Española de Investigación) / DRESSAGE (MIS5045792 funded by the Operational Program ‘Competitiveness, Entrepreneurship and Innovation’, EPAnEK 2014-2020, NSRF) / HYPOXIA (5381 funded by Operational Program “Education and Lifelong Learning”, NSRF– ARISTEIA II) / PERSEUS (funded by EU FP7 Grant Agreement No. 287600) / CLIMPACT II

Grant Number

ARC Number : DE170101524

Comments

Apostolaki, E. T., Efthymiadis, P. T., Gerakaris, V., Garcia-Escudero, C. A., Sebos, I., Vlachaki, D., Mateo, M., Lavery, P. S., & Serrano, O. (2026). The untapped potential of Poseidon grass in Greece as a hotspot for climate change mitigation. Regional Environmental Change, 26. https://doi.org/10.1007/s10113-025-02503-9

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Link to publisher version (DOI)

10.1007/s10113-025-02503-9