For Global Marine Life, A Much-Needed Checkup

We know our oceans are in trouble, but we’re not sure just how much. Leading up to World Oceans Day on June 8th, this week we’re spotlighting how some of our staff and partners are using science to assess the health of our global oceans and determine the most effective way to conserve them.

Clownfish in the Solomon Islands

Clownfish in the Solomon Islands. (© Jennifer Will)

The oceans are home to an estimated 2.2 million species, ranging from tiny single-celled organisms to blue whales, the largest living animals on the planet. Yet we understand relatively little about this incredible diversity. Even though our scientific models tell us there are millions of species, we have not actually located or named 90% of them. Of those that we have identified, only a small percentage has actually been assessed by scientists to determine whether their populations are stable, declining or increasing.

People value this diverse marine life for many reasons — as sources of food, potential medicines and tourism revenue. However, there is also the simple “existence value” — just knowing that our planet contains such an amazing variety of species.

Many of us feel a pull to see a species or a habitat that we have never seen before, or to visit a place that has the highest numbers of fish, turtles or sharks in the world, or is home to one of the world’s rarest species. I have my own wish list of places that I would love to go — including the Bird’s Head Seascape, a place where CI works that has some of the highest numbers of species in the world. I’m hoping one day I can get in the water with some of their famous whale sharks.

We still have much to do to protect the world’s marine life so that we don’t lose critical services like coastal protection, food provision and carbon storage. In order to do this, countries need tools that can help them measure how well they are doing at maintaining biodiversity.

This is where the Ocean Health Index comes in. A collaborative project of over 60 ocean experts from CI and partners, the Index is the first comprehensive assessment of the health of the oceans that is framed in terms of the many benefits humans derive from them.

We developed the Index’s biodiversity goal to determine how well marine biodiversity is faring in 151 countries’ exclusive economic zones (EEZs), the parts of the ocean that each country controls, stretching 200 miles [about 322 kilometers] from their coastlines out into the open ocean. We used publicly available datasets on the extinction risk of species from the IUCN Red List and data on the extent and condition of key marine habitats like coral reefs, mangroves, seagrasses and sea ice.

We then integrated measures of social and ecological pressures that negatively impact biodiversity, such as fishing pressure, habitat destruction, climate change, water pollution and species introductions. We also accounted for social and governance factors that should improve the condition of species and habitats, such as the extent of a country’s EEZ that is protected and whether the country has signed onto key international agreements like the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), which regulates the trade of wild animals and plants.

The results of our work and a detailed look at all of the underlying data and analyses were published last month in PLoS ONE. Our results provide an integrative picture of how species and the habitats that they build are doing globally.

spearfishing in Brazil's Bahia region

A man spearfishes in Brazil’s Bahia region. The important role of marine biodiversity in human food security is just one of the factors examined by the Ocean Health Index in assessing the health of ocean species. (© Paul Nicklen)

Some key results from our work:

  • Biodiversity scores were lowest in many of West Africa’s EEZs, while Russia, Finland and Canada had the highest scores.
  • Alarmingly, species are expected to decline over the next five years in almost every country’s EEZ.
  • Habitat condition is generally declining in developing countries in the tropics, but we also saw declines in some developed countries like the United States. Although many marine habitats have undergone recent declines, we found that Canada, Russia, Australia and many countries in Europe have improved the condition of marine habitats within their EEZs since the early 1980s, which we set as our benchmark.
  • We found a strong positive relationship between the Human Development Index and resilience scores, which includes measures of governance based on the Worldwide Governance Indicators. The Human Development Index ranks the development level of countries based on their life expectancy, education levels and income. The Worldwide Governance Indicators project ranks countries based on metrics like government effectiveness and control of corruption. This relationship means that places that are less developed are also less likely to have effective measures in place to improve the management of their biodiversity.
Ocean Health Index scores for (A) overall biodiversity, (B) species, and (C) habitats.

Ocean Health Index scores for (A) overall biodiversity, (B) species, and (C) habitats. The higher the number, the better the score. (doi:10.1371/journal.pone.0060284.g002)

We struggled with a number of challenges in trying to measure biodiversity. One issue was how to set a reasonable target for what we think is “healthy” for species and habitats. This is a very contentious issue, because there can be many visions of what is “healthy.” For some, “healthy” may mean being able to do a favorite wildlife-viewing activity, such as scuba diving. Others may feel that a system is only healthy when it is pristine and no human activity is allowed.

Our research results suggest that we need to work hard in order to meet international policy commitments like those in the Convention on Biological Diversity (CBD). Countries that signed on to the CBD committed to several steps including aiming to reduce natural habitat decline by 50% and prevent the extinction of threatened species. Tools like the OHI biodiversity goal can play a role in tracking our progress.

In order to get the best measurements to determine the health of the ocean’s biodiversity, we also need to redouble efforts to understand marine diversity. We’ve sent fewer people to the deep oceans than we have sent to outer space; however, even marine ecosystems that are easier to reach, like salt marshes, lack the global monitoring that makes it possible to measure changes in their condition.

By creating a measure of how successfully countries are preserving their biodiversity, we hope to spur action to protect the diversity in our oceans for future generations to benefit from — and simply enjoy.

Elizabeth Selig is the director of marine science in CI’s Betty and Gordon Moore Center for Science and Oceans. The Ocean Health Index was developed with the contributions of more than 65 ocean experts including the National Centre for Ecological Analysis and Synthesis and the University of British Colombia’s Sea Around Us project. The founding partners of the Index are CI, the National Geographic Society and the New England Aquarium, and the founding presenting sponsor is the Pacific Life Foundation.

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  1. Pingback: Q&A with Nan Hauser, Whale Wonder Woman | Human Nature - Conservation International Blog

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