Young mussels are ideal for ecosystem restoration 

In an innovative approach to ecosystem restoration, marine biologist Jildou Schotanus has demonstrated that the establishment of mussel beds in aquatic environments like the Wadden Sea can be significantly enhanced through the use of protective structures. 

Conducting her research at the Royal Netherlands Institute for Sea Research in Yerseke, Schotanus has brought to light the vital role of mussels as ecosystem engineers, capable of altering their surroundings to benefit not only themselves but also a wide array of other marine life.

Reshaping ecosystems

Mussels are not merely inhabitants of their environments but are active participants in shaping them. By forming large banks, these bivalves create conditions that favor the settlement of other mussels, while simultaneously offering refuge and a habitat for various plants and animals. 

The ability of mussels to trap silt and sand, as well as to reduce the force of waves during storms, underscores their importance in maintaining the ecological balance and integrity of marine ecosystems. “For this reason, there are lots of initiatives to restore mussel beds,” said Schotanus. “But it is, usually, a daunting task!”

Restoring mussel beds 

One of the problems in restoring mussel beds is the type of mussel that is used, noted Schotanus. “In the past, adult mussels that were not used to dry conditions of intertidal mud flats were often used for this purpose. But if you suddenly try to get these mussels to settle on a mudflat that is exposed to air during low tide, where they also have to endure much more wave energy, they turn out to be unaccustomed to these conditions.” 

“Experiments we have done with very small mussels, the so-called mussel seed, show that these are still flexible enough to adapt to the rougher conditions on the tidal flats.”

Testing various strategies 

On the banks of the Oosterschelde, Schotanus investigated how mussels could be given the best head start. She experimented with breakwaters, netting to keep hungry crabs away, and with coir mats to help the shellfish adhere to the bottom. 

“All of these methods do work to some extent, but they are also very labor intensive,” said Schotanus. She found that relatively simple fencing seemed the most efficient strategy. This method provides a sheltered environment for young mussels, promoting their survival and growth.

Wildlife interactions

An interesting aspect of Schotanus’s study involves the response of avian species to the restoration structures. Using camera surveillance, the researchers observed that birds such as curlews and oystercatchers initially showed hesitation towards the unfamiliar installations. Over time, however, these birds adapted.

“They appear to get used to them after a while,” said Schotanus. “Gulls found the larger quantities of shellfish near the fences very quickly anyway. Oystercatchers needed some time and curlews also only discovered after some time, that there were also many small crabs near the fences, which is their favorite food.”

According to Schotanus, the most important lesson from her research is that in restoring mussel beds, you must take advantage of the positive interactions between the shellfish themselves. “Mussels simply find strength and safety in numbers. All our artificial tools have their drawbacks, so the simpler we can make it for the mussels, the better.”

Marine ecosystem restoration 

Marine ecosystem restoration involves a range of activities aimed at repairing and revitalizing aquatic environments that have been degraded, damaged, or destroyed. This process is crucial for the health of the planet, as marine ecosystems play vital roles in supporting biodiversity, regulating climate, and providing resources and services that humans rely on, such as fisheries and coastal protection.

Coral reefs 

Restoration efforts can take many forms, depending on the specific ecosystem and the challenges it faces. For coral reefs, restoration might involve the cultivation and transplantation of coral fragments to rebuild reef structures and boost biodiversity. These activities often require careful selection of coral species that are resilient to warming waters and other stressors.

Wetlands 

In the case of mangroves and salt marshes, restoration can involve replanting vegetation that has been removed or destroyed. These ecosystems are critical for carbon sequestration, shoreline stabilization, and as nurseries for marine life. Replanting helps to restore their ecological functions and benefits to local communities, including flood protection and improved water quality.

Seagrass meadows 

Seagrass meadows are restored by replanting seagrass shoots in areas where they have been lost, often due to pollution, anchoring, or dredging. Restoring seagrass meadows can improve water quality, support fish populations, and sequester carbon, helping to mitigate climate change.

Broader efforts

Beyond specific habitat restoration, broader approaches include reducing pollution inputs, such as nutrients and plastics, that harm marine ecosystems. Regulations and cleanup efforts aim to reduce the impact of these pollutants, while sustainable fisheries management practices seek to ensure that fish stocks and their habitats are preserved for the future.

Protected areas

Marine protected areas (MPAs) play a crucial role in restoration efforts by providing safe havens where ecosystems can recover and thrive without human interference. MPAs can help to replenish overfished stocks, protect endangered species, and allow ecological processes to function naturally.

Ultimate goal 

The ultimate goal of marine ecosystem restoration is to create resilient, functioning ecosystems that can sustain their biodiversity and services for future generations. This not only involves the recovery of specific habitats or species but also a commitment to maintaining the health of the marine environment as a whole through sustainable management and conservation practices.

Image Credit: Edwin Paree

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