Health can be assessed in many different ways—temperature, blood pressure, pulse, and respiratory rate are all measures of human health. But how do we know if the oceans are healthy? Scientists recently developed an index to answer that question.
The oceans play a critical role in supporting life on Earth. As noted oceanographer Sylvia Earle has repeatedly said, “No blue, no green.” Not only is the ocean responsible for providing half of the planet’s oxygen and regulating the global climate, but it also provides humans with food, livelihoods, and opportunities for recreation.
In order to take all of these components into account, scientists have created an index composed of ten diverse factors that contribute to the health of the oceans and the benefits they provide to humans. The assessment, published in Nature this week, calculated the index for every coastal country individually, as well as a combined global health index.
Globally, the ocean health index was 60 out of 100, with developed countries generally performing better than developing countries, with a few noticeable exceptions—Poland and Singapore, both developed countries, scored poorly, while the developing countries of Suriname and Seychelles had relatively high scores. West African, Middle Eastern, and Central American countries scored poorly, while parts of Northern Europe, Canada, Australia, Japan, and various tropical island countries and uninhabited regions scored highly.
Only five percent of countries scored higher than a 70, whereas 32 percent scored below 50. Index scores were significantly correlated with the Human Development Index, in part because developed countries tend to have stronger economies, better regulations and better infrastructure.
To an extent, the index quantifies what we already knew: human activities such as overfishing, coastal development, and pollution have already taken their toll, altering marine ecosystems and the services they provide now, and for future generations. But it could also be used as a tool to help keep further damage from accumulating.
Ecosystem-based management—an environmental management approach that recognizes the full array of interactions within an ecosystem—has come to the forefront through recent initiatives such as the US National Ocean Policy and the EU Marine Strategy. Rather than looking at a single issue or species, this approach takes a comprehensive look at all factors, including humans. While ecosystem-based management relies heavily on the concept of ocean health, before this work, there were few guidelines for how to measure it.
The ocean health index could be just the tool needed. It focuses on waters within the global and exclusive economic zone (EEZ), which includes nearly all continental shelf area and produces the vast majority of food, natural resources, recreation, livelihoods, and other benefits to humans. Countries with identical or similar scores show that there are different paths for achieving any given index score, and provide guidance on areas that can be improved upon. The United States and The United Kingdom had similar scores, but the US scored higher for coastal protection and coastal livelihoods and economies, while the United Kingdom scored higher for food provision and natural products.
More generally, the index provided information about global trends. Food provisioning from wild-caught fisheries and mariculture was far below what it could be if wild fish were caught more sustainably and sustainable mariculture was increased. Coastal habitat loss, which affects multiple goals and reduced the index scores of many of the countries that scored poorly, could be significantly improved through restoration and increased protection.
This index can be a powerful tool to raise public awareness, direct resource management, improve policy, and direct scientific research. By demonstrating how ocean issues fit into a broader context, the index opens the dialogue about how to use or protect the oceans.