Ecosystem Restoration

Seagrass meadow in the Eckernförde Bay (Picture: Jan Dierking, GEOMAR)

The United Nations has declared the current decade the Decade on Ecosystem Restoration, as it has never been more urgent to strengthen nature and restore degraded ecosystems on land and in the ocean. However, this global environmental campaign is not only focused on “repairing damaged or destroyed ecosystems” but also includes the protection of intact forests, coastal areas, and marine habitats.

The fact is: Healthy ecosystems not only support greater biodiversity but also provide more and better benefits for both people and nature. They absorb more carbon dioxide from the atmosphere, store the captured carbon in their biomass or underground, and thus help mitigate climate change.

Therefore, it is always better to protect and maintain ecosystems in a healthy state. However, if an ecosystem has already been severely damaged or destroyed, there is still a chance to restore it at least partially.

How ecosystems can get well again

Ecosystem restoration has so far mainly focused on terrestrial habitats, such as reforesting woodlands. Efforts to restore marine ecosystems have been relatively rare. However, recent progress has been made in coastal ecosystems, including mangroves, kelp forests, seagrass meadows, mussel and oyster reefs, and, to some extent, coral reefs.

Whether restoration efforts are successful depends on many factors. For example, it matters what type of ecosystem is being restored, how large and complex it was in the past, where it is located, and which techniques are used. Site-specific ecological factors, such as species selection and composition, must be carefully considered. At the same time, changing environmental conditions caused by climate change must also be taken into account.

Ecosystems can be restored in various ways, such as:

Replanting key species like mangroves and seagrasses
Reintroducing formerly native marine animals
Removing invasive algae species or other dominant disturbances
Most importantly, reducing human-induced stress factors so that ecosystems can focus all their energy on natural recovery. Some of the most significant stress factors include intensive fishing, uncontrolled pollution from waste, sewage, and harmful substances, overexploitation of coastal forests and meadows, development of crucial coastal areas, and disruptive ship and boat traffic.

Projekte zur Wiederherstellung mariner Ökosysteme

Due to global warming, seawater temperatures are rising and the oceans are becoming increasingly acidic. One consequence is major coral bleaching. In the past, the reefs were often able to help themselves after such an event. However, bleaching events are now more frequent and longer - entire coral reefs are dying. To counteract this, there are projects that restore corals.

Coral gardeners, for example, are working on restoring reefs in Vanuatu in the South Pacific. They collect small, broken coral pieces and attach them to a metal spiderweb frame. These frames with coral fragments are then placed in damaged areas, where they are intended to serve as artificial reefs and stimulate natural growth.

It is impossible to replant entire coral reefs. Instead, the coral gardeners are aiming to trigger a natural recovery. They also hope that resistance to bleaching will increase if they selectively release corals that have proved resistant in the past.

More information: https://reefresilience.org/de/case-studies/south-pacific-restoration/

Posidonia oceanica is a species of seagrass native to the Mediterranean. It grows in waters up to 40 meters deep, forming large underwater meadows that serve as important refuges and feeding grounds for hundreds of different marine species. Additionally, these meadows protect coastlines from erosion by weakening waves and stabilizing sediments. They also store significant amounts of carbon, estimated at half a million tons per year.

Nevertheless, more than half of the Posidonia beds in Europe are severely damaged. In 2010, a first EU-LIFE project was launched in Andalusia to map seagrass beds and investigate conservation needs. Measures were taken to reduce existing threats so that the habitat can recover naturally.

Since then, there have been several initiatives to restore damaged Posidonia beds. For example, fragments and seeds of seagrass cultivated under laboratory conditions were transplanted into damaged meadows. A successful experiment: 90 percent of the meadows survived to the second year. However, the cost of restoration is still high.

More information on ecosystem restoration: op.europa.eu/en/publication-detail/-/publication/95311c9d-f07b-11ec-a534-01aa75ed71a1

The future of the Caribbean is closely tied to the health of its coral reefs. The cover of living corals has decreased by 60 percent in recent decades. The destruction of the reefs threatens the population of the region, whose economy heavily depends on healthy reefs.

As part of the CoralCarib project by the International Climate Initiative (IKI), a new strategic approach for the conservation and restoration of Caribbean coral reef ecosystems is being developed. The focus is on marine biodiversity in coral reef ecosystems around four Caribbean islands (Cuba, the Dominican Republic, Haiti, and Jamaica). The project activities are designed to protect, restore, and sustainably use coral reefs that have a high potential to withstand future impacts of climate change. "Coral climate protection refuges" are to be established.

CoralCarib began in 2023 and is set to be implemented over a six-year period.

More information: https://www.international-climate-initiative.com/projekt/coralcarib-entwicklung-eines-neuen-strategischen-ansatzes-fuer-die-erhaltung-und-wiederherstellung-karibischer-korallenriff-oekosysteme-in-klimaresistenten-refugien-22-iv-106-caribbean-a-coralcarib/

Long-term protection and sustainable use

Even if there are initial successes, the task of restoring and protecting ecosystems is a huge challenge. It is rarely possible to fully return a destroyed coral reef or a deforested mangrove forest to its original state. The many interactions between the marine environment, living organisms, and nutrient cycles that make up an ecosystem are too complex for that. Additional complications arise from climate-related environmental changes, such as rising water temperatures and sea levels. These alter the physical conditions and thus the foundation of life in the ocean.

The restoration of marine ecosystems is most effective when it aims to strengthen the biodiversity and ecosystem services of natural habitats in the long term. This involves including all affected communities in the decision-making process, considering their demands on the ecosystem (such as revenue from fish, timber, or tourism), and finding sustainable compromise solutions accordingly.

Once an ecosystem is restored, all further human interventions should be reduced to a sustainable minimum.

Abelson, A., Reed, D. C., Edgar, G. J., et al. & Nelson, P. (2020). Challenges for restoration of coastal marine ecosystems in the Anthropocene. Frontiers in Marine Science, 7, 544105. doi.org/10.3389/fmars.2020.544105
Bayraktarov, E., Saunders, M. I., Abdullah, S., et al. & Lovelock, C. E. (2016). The cost and feasibility of marine coastal restoration. Ecological Applications, 26(4), 1055-1074. doi.org/10.1890/15-1077
Boström-Einarsson, L., Babcock, R. C., Bayraktarov, et al. & McLeod, I. M. (2020). Coral restoration – A systematic review of current methods, successes, failures and future directions. PloS one, 15(1), e0226631. doi.org/10.1371/journal.pone.0226631
Eger, A. M., Marzinelli, E., Gribben, P., et. al. & Vergés, A. (2020). Playing to the positives: using synergies to enhance kelp forest restoration. Frontiers in Marine Science, 544. doi.org/10.3389/fmars.2020.00544
Fuchs, G., Noebel, R. vom Ecologic Institut (2023). Die Wiederherstellung von Meeres- und Küstenökosystemen. Policy Paper Reihe zur UN-Dekade zur Wiederherstellung von Ökosystemen (2021-2030), Policy Paper Nr. 6