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Identifier

000463132

Title

Blue carbon stocks and accumulation rates of seagrass (Posidonia oceanica) meadows of the South Aegean Sea

Alternative Title

Εκτίμηση του δυναμικού των θαλάσσιων λιβαδιών, Posidonia oceanica, στην αποθήκευση μπλε άνθρακα

Author

Ευθυμιάδης, Παύλος Θεόφιλος Σ.

Thesis advisor

Καρακάσης, Ιωάννης

Reviewer

Κεντούρη, Μαρουδιώ
Αποστολάκη, Ευγενία

Abstract

Over the last decades, we are facing the consequences of the dual warming and biodiversity crisis, induced by the ever-increasing anthropogenic greenhouse gas emissions. In the context of mitigating the effects of this dual climate crisis, the concept of Blue Carbon emerges as a promising Nature based Solution. Seagrass meadows, one of the major Coastal Blue Carbon Ecosystems, ranks among the most important carbon sinks globally, estimated to bury C_org at a range from 48 to 112 Tg yr^-1 , corresponding to 10 – 18 % of the global carbon burial in the ocean sediment. Specifically, the endemic in the Mediterranean seagrass, Posidonia oceanica, is considered as a major carbon sink globally, offering multiple services enhancing coastal resilience as well. The Greek Seas present a compelling case for assessing the storage capacity and accumulation rates of P. oceanica meadows, as it constitutes the third country with its largest extent. Here, we assessed the natural variability of organic carbon (C_org) carbon stocks and long-term carbon accumulation rates (CAR) of 42 monospecific P. oceanica meadows expanding across the South Aegean Sea (Greece), and specifically within the regions of Saronikos Gulf, Cyclades Archipelago, Dodecanese Archipelago and Crete Island. Furthermore, we estimated the capacity of P. oceanica meadows of the S. Aegean to accumulate the total CO₂ emissions of the country. P. oceanica stocks and CAR showed a mean of 11.1 kg m^-2 and 25.3 g m^-2 yr^-1 , respectively. The region of Cyclades Archipelago showed the highest stocks and CAR among regions, emerging as a Blue Carbon hotspot of the Greek Seas. Furthermore, all the sedimentary biogeochemical variables tested had a significant effect on C_org content, with silt/clay and δ¹³C showing a positive effect and DBD and C_inorg a negative effect. Considering their total extent within the South Aegean, P. oceanica meadows were capable of capturing 104 kt CO_{2 eq} yr^-1 , corresponding to 0.1 % of the total CO₂ emissions of Greece for the year 2021.

Language

English

Subject

Carbon sink

Climate change mitigation

Coastal wetlands

LULUCF

Nature-based solutions

Seagrass

Θαλάσσια λιβάδια

Κλιματική αλλαγή

Μεσόγειος θάλασσα