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- Marine biodegradation of natural potential carrier substrates for seagrass restorationPublication . Pieraccini, Riccardo; Nebel, Kai; Engelen, Aschwin; Rautenbach, SarahSeagrass meadows provide essential ecosystem services but have been strongly declining over the past. Due to their incapability to recover effectively naturally, assisted restoration is used. This study aimed to test textile fabrics from natural derivatives to serve as carrier substrates for seagrass transplantation. The use of biotextile fabrics should enable seagrasses to better withstand hydrodynamic forces, especially in highenergy areas and during autumn and winter storms in the initial phase of restoration, thereby increasing restoration success. Here, the biodegradation behavior of three natural textiles was assessed in different configurations. Coir, sisal, and jute meshes were fixed on the top and bottom of a coir nonwoven mat, forming a so-called “sandwich structure.” Specimens were buried in the Ria Formosa Lagoon, Portugal, and retrieved weekly within the first months of burial and subsequently monthly over a total period of 3 months. Weight, tensile strength, and oxygen consumption rate were used as descriptors for biodegradation and tested after each retrieval.
- First assessment of blue carbon stocks, sequestration rates and potential sources since 1900 at Arguin Island (Mauritania)Publication . Martins, Márcio; Abrantes, Fatima; Aires, Tania; Rautenbach, Sarah; Engelen, Aschwin; Encarnação, João Pedro da Silva; Abecasis, David; Gandega, Cheikhna; Magalhães, Vitor; Brahim, Khallahi; Ebaye, Sidina; Barusseau, Jean-Paul; Freiwald, André; Barrena de los Santos, Carmen; Serrao, Ester A.; Santos, RuiGlobal blue carbon assessments are hindered by a lack of data from understudied seagrass regions, such as those of Western Africa. This study reports the first in situ records of organic carbon (OC) stocks and burial rates for seagrass beds at Arguin Island, Banc d'Arguin (Mauritania), Western Africa, measured in intertidal Zostera noltei and subtidal Cymodocea nodosa meadows. The major blue carbon sources in seagrass meadows since 1900 were assessed using sedimentary environmental DNA (eDNA) and chronostratigraphy. The OC stocks in the top 50 cm of the sediment cores were not significantly different between the beds of the two seagrass species and averaged 27.8±7.14 Mg C ha−1, which is 5 times higher than that in adjacent unvegetated sediments. The OC sequestration rate for the past 100 years was 10.3±1.4 g C m−2 year−1 in C. nodosa sediments and 12.3±5.9 g C m−2 year−1 in Z. noltei sediments. Sedimentary eDNA analysis revealed that the major OC source within the C. nodosa and Z. noltei sediments has been the seagrass species itself, with low contributions from allochthonous eDNA reads. Carbon sources in Z. noltei meadows were more diverse than those in C. nodosa meadows. In bare sediment, diatoms were the major carbon source. The present study demonstrates the potential of sedimentary eDNA to reveal the major sources of organic matter in blue carbon ecosystems, improving our understanding of the provenance of sedimentary OC and thus carbon cycling processes. Additionally, it provides new OC stock and sequestration rate measurements from a region of the world that remains underrepresented in global blue carbon assessments.