Restoration of Cymodocea nodosa Meadows: "Los Jardineros del Mar"- A Revival Project for Marine Ecosystems in the Canary Islands.
Seagrasses, often mistaken for simple algae, are actually complex and highly adapted marine plants. Unlike algae, seagrasses such as Cymodocea nodosa (Fig. 1) have roots, stems, and leaves, and are even capable of flowering and producing fruits underwater. These marine plants form extensive meadows on the seabed, known as sebadales in the Canary Islands, which play a crucial role in marine ecosystems (Gonzalez-Lorenzo et al., 2020; Ribeiro et al., 2022). Seagrasses are considered “ecosystem engineers”: they not only provide habitat and food for a wide range of species but also help improve water quality, stabilize sediment on the seabed, and protect coastlines from erosion.
Unfortunately, seagrasses are facing a global decline, with a loss rate of 5% per year due to factors such as pollution, climate change, and human activities (Duarte et al., 2008; Casas et al., 2021). It is precisely to counter this regression that restoration projects, such as the one led by Innoceana in Tenerife, are essential for protecting and preserving these vital ecosystems.
Scientific Name: Cymodocea nodosa (Ucria) Ascherson.
Common Name: Little Neptune Grass.
Taxonomic Group: Subphylum Angiosperms, Family Cymodoceaceae.
Why is restoring Cymodocea nodosa meadows crucial?
Particularly in the province of Santa Cruz de Tenerife, Cymodocea nodosa meadows have experienced a 10% reduction over the last ten years (Monterroso et al., 2015). This decline is due to global impacts such as ocean acidification, global warming, and pollution, as well as local impacts from human coastal activities including wastewater discharges, anchoring, and coastal construction (Casas et al., 2022; Menicagli et al., 2022; Ribeiro et al., 2022).
Currently, Cymodocea nodosa meadows in the Canary Islands are classified as Vulnerable in the Spanish Catalogue of Endangered Species (CEEA) and are recognized as priority habitats for protection under the Habitats Directive and other international conservation frameworks (OSPAR and Bern).
The restoration project: a hope for the future
To counter this regression, Innoceana has launched an ambitious restoration project called “Los Jardineros del Mar” (“The Sea Gardeners”) involving two type of sites (Fig 2):
Figure 2: Map showing the Cymodocea nodosa meadows until 2018 and the restoration sites.
- Donor site: Abades, Tenerife Island
This site was selected for its excellent health of Cymodocea nodosa meadows and their abundant presence at depths between 6 and 17 meters. Protected from prevailing winds and with ideal diving conditions for most of the year, Abades provides an excellent base for collecting and transplanting samples. - Transplant site: Playa San Juan, Tenerife Island
The restoration area is located in the southwest of the island, characterized by a sandy bed next to a rocky wall, with a gentle slope starting at 8 meters depth. The transplant site, at 12 meters depth, presents ideal environmental conditions for the development and dispersion of Cymodocea nodosa meadows.
Results and monitoring: signs of success
Thanks to regular monitoring, carried out at least once a month, Innoceana has been able to follow closely the survival and growth rate of the transplanted individuals (Fig. 3). So far, the restoration project has shown promising results. Consistent monitoring of the transplanted individuals have revealed developments in both plant growth and health, confirming the effectiveness of the restoration efforts. This monitoring not only tracks changes over time but also helps identify potential issues early on, allowing for quick adjustments. The data gathered provides valuable insights into the ideal conditions for seagrass growth and propagation, helping to refine the restoration techniques used. This long-term approach ensures the project can adapt to changes in the marine environment, increasing the chances of fully restoring these important ecosystems.
Figure 3: Innoceana team measuring Cymodocea nodosa leaves for monthly monitoring.
Conclusions and future prospects
The restoration of Cymodocea nodosa meadows not only supports marine biodiversity but also improves water quality and protects coastlines. These seagrass meadows act as natural filters, reducing water turbidity and providing essential habitat for marine species.
However, conservation efforts must also address ongoing environmental stresses such as pollution and climate change. Strategies include improving waste management, regulating coastal development, and enhancing climate resilience.
In addition to the current in-situ techniques, one potential approach to consider for future projects is the adoption of ex-situ methods. These techniques involve collecting seeds or naturally uprooted plants collected in the surroundings of meadows and growing them in controlled environments outside their natural habitat. Ex-situ methods offer benefits such as precise environmental control, the ability to produce plants on a larger scale, and, most importantly, a low impact on donor meadows, as we only collect seeds or naturally uprooted plants. However, they also present challenges, including high costs, complex infrastructure, and difficulties in ensuring that plants adapted to artificial settings can thrive when reintroduced to natural conditions.
In summary, integrating both in-situ and ex-situ techniques could optimize restoration outcomes and enhance the long-term resilience of marine ecosystems.
References
Casas, E., Martín-García, L., Otero-Ferrer, F., Tuya, F., Haroun, R., Arbelo, M., 2021. Economic mapping and assessment of Cymodocea nodosa meadows as nursery grounds for commercially important fish species. A case study in the Canary Islands. OE 6, e70919. https://doi.org/10.3897/oneeco.6.e70919
Duarte, C.M., Dennison, W.C., Orth, R.J.W. et al. The Charisma of Coastal Ecosystems: Addressing the Imbalance. Estuaries and Coasts: J CERF 31, 233–238 (2008). https://doi.org/10.1007/s12237-008-9038-7
Gonzalez-Lorenzo, G., Toledo-Guedes, K., Rodríguez-Riesco, E., González-Méndez, E., González-Rodríguez, Y., Piñeiro-Corbeira, C., 2020. The underreported presence of the subtidal seagrass Cymodocea nodosa in rocky intertidal pools of the Canary Islands. Marine Biology Research 16, 550–555. https://doi.org/10.1080/17451000.2020.1834583
Menicagli, V., Castiglione, M.R., Balestri, E., Giorgetti, L., Bottega, S., Sorce, C., Spanò, C., Lardicci, C., 2022. Early evidence of the impacts of microplastic and nanoplastic pollution on the growth and physiology of the seagrass Cymodocea nodosa. Science of The Total Environment 838, 156514. https://doi.org/10.1016/j.scitotenv.2022.156514
Monterroso, O., Rodríguez, M., Pérez, O., Ramos, E., Álvarez, O., Cruces, L., Ruiz, M., Miguel, A., & González, M. (2018). Memoria final del estudio “Cartografía de Cymodocea nodosa en Tenerife y La Gomera”. Viceconsejería de Medio Ambiente del Gobierno de Canarias. Dirección General de Protección de la Naturaleza. Diciembre 2018. Cima -Informe Técnico 2018-30: 164 pp.
Ribeiro, C., Neves, P., Kaufmann, M., Araújo, R., Riera, R., 2022. A baseline for prioritizing the conservation of the threatened seagrass Cymodocea nodosa in the oceanic archipelago of Madeira. Journal for Nature Conservation 68, 126224. https://doi.org/10.1016/j.jnc.2022.126224