Restorative aquaculture shows we can have more habitat and eat it too


For the first time, The Nature Conservancy (TNC), in collaboration with scientists from the University of New England, the University of Melbourne and the University of Adelaide, conducted a comprehensive global review of the literature and an analysis of 65 studies to quantify the relative habitat benefits of mussel, oyster, clam and seaweed farming. The results of this work show that culture systems for these species have resulted in an increase in the abundance and diversity of fish and invertebrates compared to similar sites without farms present.

However, different aquaculture species and farming methods have different outcomes for nature. Bivalve aquaculture – two-shelled animals like mussels, oysters and clams – appears to provide habitat more efficiently than algae aquaculture, although there is less research available reflecting the impact and the advantages of a wide variety of seaweed cultivation methods and species.

Learn from previous studies

The study shows that mussel farms tend to attract the greatest abundance of organisms – on average about 3.6 times more fish and invertebrates compared to nearby reference sites. Oyster beds, on the other hand, attract the greatest diversity of species, with 1.3 times the diversity compared to reference sites.

Beyond providing habitat itself, algae and shellfish farms also have the potential to increase habitat value, or the ability of wild organisms to survive and reproduce. Smaller organisms can use the farm structure as a refuge from predators, as well as eat farm produce and other organisms that live on the farm. Large predators may also be attracted to farms for livestock product, or as a hunting ground for small fish or invertebrates that live around farms. And all organisms that survive and reproduce provide food to predators through their offspring.

Many bivalves are broadcast breeders that send their offspring into the water column, the survivors float or swim to settle elsewhere, establishing or sustaining wild populations. Agricultural structures can also help produce habitat benefits by reducing environmental stresses. Farms can help dissipate wave energy and reduce other types of physical challenges.

Aquaculture as habitat

Similar to many environmental sustainability considerations affecting other industries, the secret to successful habitat creation for algae and mollusk aquaculture is careful farm planning and diligence throughout the life cycle. production. Overcrowded farms, poorly rinsed by currents, built on existing habitats such as reefs or seagrass beds, or producing plastic pollution can in fact have harmful effects on the ecosystem.

Research suggests that in large quantities or in high densities, animals that filter water to eat – for example, bivalves – can consume so much food, oxygen and nutrients in the water than other organisms. may become stressed and struggle to survive. And, like all animals, bivalves must release their digested food somewhere. In fact, organisms like oysters produce both digested and undigested waste (called pseudo-faeces), which sink to the bottom.

While bivalves actively removing sediment and certain nutrients from the water column can do wonders for water clarity, overaccumulation of wastes under agricultural sites can cover benthic organisms. This can lead to an imbalance in benthic processes and can even suffocate organisms to death. These challenges can be overcome by considering the location of farms and livestock at appropriate densities.

Overall, the drivers of habitat value depend on the interplay of local environmental conditions, intensity and scale, gear used, species cultivated, and farm management practices. To avoid the negative impacts of overcrowding or oversized farms, scientifically based choice of aquaculture sites and analysis of the above factors is required.

Develop aquaculture to obtain results on the habitat

The article demonstrates a vast potential for food production in harmony with ocean ecosystems.

“We want to better understand how food production can go beyond impact reduction and actually deliver benefits to the ocean,” says Robert Jones, one of the authors of the article.

“We can work towards the United Nations Sustainable Development Goals of zero hunger and protect – or better yet – repair damage to our oceans at the same time. This research is a significant step forward in demonstrating – through scientifically substantiated figures – that this is possible. “

These findings are essential for rethinking how food production systems can meet human needs, while providing “restorative” benefits to our ecosystems as a whole. Fish consumption and the aquaculture industry are currently the fastest growing protein choice for feed and food production in the world. There is therefore an urgent need to scale up solutions that can deliver seafood without damaging ecosystems.

The authors of this study point out that while strong planning at the farm level is essential to responsibly create habitat through aquaculture, collaborative policy can drive change on a larger scale. Conservation efforts, such as marine protected areas, have historically had limited opportunities for shellfish farming and seaweed aquaculture due to its status as an industry, while well-managed farms can actually help achieve goals. conservation efforts targeted by these efforts. Innovative collaborations between state or local governance and those affected by such policies can lead to new ways of thinking about and managing the social and environmental aspects of shellfish and shellfish farming.

With an increasing body of research quantifying the effects of algae and mollusc aquaculture, the realization of the local, regional and global benefits of such practices becomes more tangible. Understanding the habitat benefits and best management practices needed to deliver these benefits to bivalve and algae aquaculture is an important step in the direction of providing sustainable food for people and essential benefits. for the environment.

Going forward, scientists and planners can work to determine where and how seashells and algae provide habitat, how to most effectively and responsibly encourage restoration practices in these areas, and how this change can benefit people. marine ecosystems and communities in general.


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