Marine and coastal ecosystem services

When we analyze interactions within an ecosystem, we can identify which services each ecosystem produces. These services are diverse: fish make up the primary source of protein for a billion people worldwide, forests absorb a substantial amount of greenhouse gas emissions, etc. Therefore the concept of ecosystem services was created to recognize and quantify all beneficial interactions to human populations. A famous example concerns pollination: when bees visit flowers to gather nectar, they transport pollen grains from one flower to the other, thereby participating in plant reproduction.

But ecosystem services are not limited to the terrestrial space. On the contrary, the ocean plays a major role in climate regulation. Studies have shown that the seas absorb almost a third of the carbon dioxide emitted annually. Moreover, marine and coastal ecosystems are home to numerous plant and animal species, which all produce various useful services for humans. For instance, mangroves help retain friable, or crumbly, soil on the coast, and therefore help prevent coastal erosion. They are also natural barriers to water currents, and as such constitute a favoured habitat for the birth and development of many species of fish. Mangroves therefore help maintain the available fish stock. Whale feces, on the other hand, contain high quantities of iron, which is an essential nutrient for photosynthesis. The level of iron present in the ocean has a direct impact on the development of phytoplankton, a key component of carbon storage.

The Millennium Ecosystem Assessment (MEA) defined four types of ecosystem services. Marine and coastal ecosystems produce various services, including:

• provisioning services: fisheries, building materials;
• supporting services: life-cycle maintenance for both fauna and local, element and nutrient cycling;
• regulating services: carbon sequestration and storage, erosion prevention, waste-water treatment, moderation of extreme events;
• cultural services: tourism, recreational, aesthetic, and spiritual benefits.

The total value of the services produced by marine and coastal ecosystems is valued at USD$ 29.5 trillion per year, which is worth more than the USA’s gross national product in 2015. However, the quality of these services depends on the ecosystems’ resilience and its level of protection. When an ecosystem is degraded, it delivers fewer services. For instance, posidonia meadows are underwater flowering plants in the Mediterranean Sea. These plants are very vulnerable to human disturbance. Natural habitats are threatened by growing coastal urbanization, as well as by the increasing amount of boats, whose anchors wrench posidonia plants out. Yet these meadows are crucial to the fight against coastal erosion. Moreover, these plants constitute a safe haven for fish to reproduce and establish nurseries for their offspring as they protect juvenile fish from predators. The destruction of Posidonia plants reduces the overall fish stock, which in turn has a negative impact on fishermen and recreational divers.

Furthermore, ecosystems offer great, but underrated, opportunities. Cultural services are often overlooked when computing the total value of the ocean, because such services are difficult to value. The fishing industry is an important business sector in many countries, but we tend to forget that the sea is a major cultural arena. From tourism to navigation to the arts, the sea is a place to relax and be inspired. The ocean is also a source of economic growth, particularly for biotechnologies, which consist in developing goods out of biological principles seen in nature. For instance, the analysis of the poison contained in cone snails helped isolate ziconotide, an analgesic agent currently used in the medical sector. And yet, the ocean remains relatively understudied. Many more practical applications of great use to mankind could still be discovered.

For ecosystems to keep supplying many services, we need to preserve them, i.e. to protect biodiversity and reduce to a minimum the human impact on ecosystem functions. Protecting marine biodiversity means protecting the climate and thus protecting humans.