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The silent work of the Ocean

By Aline S. Martinez

English edit by Malu Abieri and Carla Elliff

Have you ever heard about the ecological functions of marine organisms and ecosystems? What about the services they provide to society?

Illustration by Joana Ho

You may have already heard that phytoplankton, the tiny photosynthetic organisms in the ocean, are what allow us to breathe on the planet (take a look at the post The air that you breathe). That is an example of an ecosystem service. The ecological functioning of these microalgae, which happens while they carry out their normal activities to stay alive, offers several benefits for the environment and also for humans. Through photosynthesis, microalgae produce the oxygen that we humans depend on and breathe.

Likewise, there are other marine organisms and ecosystems that produce various services on which we depend for our survival.

In addition to the intrinsic value of biodiversity, ecosystems are part of our natural capital, representing the basis on which we develop all our activities and draw all our resources for life as we know it. Coastal environments, for example, provide services to society worth approximately $52 trillion per year. This estimate is based either on the profits generated by each ecosystem or the cost to build something that performs the same function as a natural ecosystem, such as the economic value of lobster in seafood markets, tourism packages in coral reefs or the cost of building coastal storm surge barriers. The conservation of biodiversity and health of the seas is key to maintaining the proper functioning of ecosystems and, consequently, maintaining the provision of these valuable services. But, to better understand what makes them so valuable to us, let's explain what they are and how these services benefit us.

Ecosystem services are usually divided into four main categories, these being supporting, cultural, provisioning, and regulating services. Supporting services are primarily related to habitat-forming organisms, known as founder species. Among these, corals, macroalgae, mussels and salt marshes stand out. The physical structure of these organisms provides housing for several species, refuge from predators, and climate protection. In addition, the habitat provided by these organisms works as feeding grounds and a nursery area for many species, including some of economic interest, such as lobsters, which live in shallow water reef environments, and fish, which live in mangroves and sea grasses.

Cultural services refer to non-material benefits of ecosystems obtained by human beings through cognitive development, aesthetic and recreational experiences and “spiritual” enrichment. This includes the pleasure obtained from resting on the beach to the sound of the waves, the admiration and joy resulting from observing animals moving among the corals or even the spiritual comfort in offering and praying activities associated with gods or spiritual guides of the sea (such as Iemanjá).

Several people standing at a rocky beach wearing white clothes.

Religious people performing a ritual of worship and offering to Iemanjá, the Queen of the Sea in Candomblé, at Praia do Rio Vermelho in Salvador, BA (Photo: Carla Elliff).

Provisioning services, or goods, include everything we can extract from the ocean, such as the fish we eat, energy and mineral resources, algae extracts and sponges to produce medicines, and even beach sand for use in civil constructions.

Shrimps, oysters, crabs disposed over ice on a table.

Diverse types of seafood that are consumed by us, humans (Photo by Chait Goli, Pexels).

Regulation services, in turn, include all functions or activities that marine beings perform, regulating physical and chemical processes in the ecosystem. For example, mangrove plants and salt marshes store large amounts of carbon in their tissues and in the sediments that are trapped between their roots. That is an extremely important role in Earth's climate regulation. Without carbon storage in ocean soils, the greenhouse effect on Earth would greatly increase, intensifying global warming. In addition to storing carbon, these ecosystems are important for coastal protection, as mangroves and salt marshes have the ability to dampen the energy of waves that reach the coast, functioning as natural breakwaters.

A white heron standing near the water of a estuary, mangrove trees are on the back,

Mangrove during low tide, exposing the supporting roots typical of this vegetation (Photo by Alice Reis).

Other organisms that also have the ability to provide this ecosystem service of shoreline protection and erosion regulation are coral reefs. Oysters and mussels, in addition to protecting the coast, by firmly adhering to the substrate forming a rigid natural structure, are also sources of human food, habitat builders and play an important role in water purification. As they feed by filtering particles that are in the water column, they end up removing impurities from the water. Through filtration, these organisms contribute to good water quality, preventing eutrophication and providing clean beaches for us to enjoy. As you can see, the same ecosystem or group of organisms can provide several different services at the same time!

Oysters attached to the mangrove roots (Photo by Alice Reis).

The work I have been developing seeks to understand how anthropogenic stressors (i.e., physical, chemical or biological changes to the environment caused by human activities) are altering the functioning of ecosystems. We have a good idea of the importance of these systems for our benefit, but we still do not know the consequences of so many changes that have been occurring associated with the rapid growth of coastal cities.

Recently, we discovered that mussel filtration is affected by metal contamination, indicating that these organisms are stressed but still maintaining their biological functions. The increase in this contamination was directly related to the increase in urbanized areas on the coast, which indicates that the expansion of coastal cities will increase the amount of pollution on the coast. What we don't yet know is the contamination threshold that mussels can withstand. Therefore, my work seeks to better understand how we are affecting coastal systems to seek solutions that prevent the collapse of ecosystems. This would be an irreparable loss for human beings.

Well, I hope to have clarified here the relationship between ecological functioning and the services provided by ecosystems, which shows us the importance of taking good care of the environment. The examples I described above are just some of the many goods and services that nature provides us. Unfortunately, we are looking out for the health of marine ecosystems, and we already have evidence that our actions cause damage to these ecosystems.

If we do not manage our actions in a sustainable way, we run the risk of not enjoying the many benefits that the sea so generously gives us. It is important to rethink our attitudes towards the environment and our consumption choices so that we can seek a balance between nature and society.

Now that you know more about some of the benefits we obtain from healthy and balanced ecosystems, I'm sure you'll look at the sea with different eyes on your next visit to the beach! Enjoy and spread these ideas around... our ocean will thank you!



Barbier, E.B., 2017. Marine ecosystem services. Current Biology 27, R507-R510.

Austen, M., Hattam, C., Borger, T., 2015. Ecosystem services and benefits from marine ecosystems, in: Crowe, T.P., Frid, C.L.J. (Eds.), Marine Ecosystems: Human Impacts on Biodiversity, Functioning and Services. Cambridge University Press, United Kingdom, pp. 21-41.

Costanza, R., de Groot, R., Sutton, P., van der Ploeg, S., Anderson, S.J., Kubiszewski, I., Farber, S., Turner, R.K., 2014. Changes in the global value of ecosystem services. Global Environmental Change 26, 152-158.

Martinez, A.S., Mayer-Pinto, M., Christofoletti, R.A., 2019. Functional responses of filter feeders increase with elevated metal contamination: Are these good or bad signs of environmental health? Marine Pollution Bulletin 149, 110571.


About the author:

I am an oceanographer with a degree from the Federal University of Rio Grande (FURG) and a PhD in ecology from the University of Sydney (USYD). Born in Minas, the sea was love at first sight. Since I was little, I have been passionate about nature and have been enchanted by the mysteries of the bottom of the sea. I work with benthic ecology, where I investigate the effect of human activities on the structure and functioning of benthic communities in coastal ecosystems. Throughout my career I have worked on environmental management, education and conservation projects, and environmental consultancy work, in addition to developing the aforementioned line of research. Through my scientific work, I aim to seek solutions so that we can live in harmony with nature.

But the sea is not just my object of study. I have a very strong connection with him. In my leisure time, I love diving, surfing and photographing marine life.

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