Invasive Species: Threat or Opportunity?

What happens when a problem leads to more than one solution? The answer often lies in observation, understanding the environment, and adapting to constantly changing conditions. Rather than trying to dominate nature, we can work with it and make use of the opportunities it offers. This is one of the fundamental principles of permaculture and provides the framework through which we can examine the case of the almeja japónica, an invasive species that was initially considered a problem but later came to play an unexpectedly important role in the communities of Galicia, Spain.

Invasive species are plants, animals, or microorganisms that are introduced into a new environment outside their natural range as a result of human activities. When they successfully adapt to their new surroundings, they may reproduce rapidly and negatively affect local ecosystems. They can be introduced intentionally or accidentally through ship ballast water, attached to vessel hulls, or transported in shipping containers. If not properly managed, invasive species can have significant environmental and economic impacts by displacing native species, altering ecosystem structures, and damaging agriculture, aquaculture, and infrastructure, ultimately affecting tourism and fisheries.

What Was the Problem?

During the 1980s, coastal communities in Galicia, Spain, faced a serious decline in the populations of the native clam species (almeja fina). Demand remained high, but natural stocks were unable to recover at the same rate they were being harvested. To address this production crisis, the Japanese clam (Ruditapes philippinarum) was deliberately introduced.

The Japanese clam possessed three characteristics that made it an attractive solution for restoring local income:

1. It reaches market size much faster than native clam species.

2. Its flesh is firmer and can withstand transportation without water for longer periods, making it suitable for export across Europe.

3. It is highly tolerant of fluctuations in water temperature and salinity.

However, this decision was not welcomed by everyone. As a non-native species, the Japanese clam began competing with local shellfish populations, and many feared it would alter the region's ecosystem.

Although initially criticized as an "invader," its resilience has become a significant advantage today. Climate change has increased water temperatures and intensified rainfall events, causing sudden changes in salinity in coastal areas. Native species are finding it increasingly difficult to survive under these conditions, while the Japanese clam has proven more resilient, helping to sustain the livelihoods of the mariscadoras, Galicia's traditional shellfish gatherers.

What Solutions Emerged from the Problem?

Rather than viewing an invasive species solely as a threat, we can explore how its characteristics and behavior might be integrated into a useful and circular system. This is where permaculture comes into play.

Permaculture, a term derived from "permanent agriculture" and "permanent culture," is a design system aimed at creating sustainable human settlements that work in harmony with nature. It focuses on the relationships between elements within a system rather than on each element individually. Observation is one of its core practices, and one of its guiding principles is that "the problem is the solution."

From this perspective, the Japanese clam can be seen not only as an invasive species but also as a resource with multiple potential benefits. Its shells are composed of calcium carbonate and can be reused as a natural soil amendment to reduce soil acidity or as a mulching material in agricultural systems. In addition, the clam acts as a natural filter feeder, removing suspended particles and algae from the water and contributing to the improvement of coastal water quality.

In recent years, Galicia has experienced a significant decline in shellfish populations due to rising temperatures and increasingly extreme weather conditions. The case of the Japanese clam demonstrates that solutions do not always come from completely eliminating a problem. Instead, they may emerge through understanding its characteristics and using them in ways that strengthen the resilience of the overall system.

As permaculture teaches, the solution is often found not in fighting a problem, but in understanding how it can be transformed into an opportunity.

Angeliki Ilia, Fundación Condado de Taboada