Seagrass is an important feature of 28 UNESCO World Heritage properties, including the Great Barrier Reef World Heritage Area off the coast of Queensland in Australia. Although the site is most famous for its iconic coral reef, it also hosts one of the largest areas of seagrass meadows in the world. In fact, without the neighbouring seagrass, the reefs as we know them would not exist. Through a myriad of ecosystem services – such as providing a safe nursery for young fish – seagrass supports adjacent ecosystems. Seagrass meadows themselves are also highly biodiverse ecosystems, supporting a huge variety of sea life.

Seagrass also provides a wealth of benefits to humans. In its role as a fish and crustacean nursery, seagrass helps to supports the global fishing industry. For local communities that rely on fishing for subsistence, the seagrass is vital for food security.

Seagrass is a highly productive plant, growing rapidly to blanket the ocean floor. In the process, it captures huge volumes of carbon dioxide and stores it below the sediment. Up to 20% of the carbon captured in the ocean is attributed to seagrass, making it one of the largest carbon sinks on the planet. As such, seagrass is critical in the fight against climate change.

However, climate change is also threatening the continued existence of seagrass. Oceans are increasingly warm and acidic, becoming inhospitable to marine plants and animals. Together with direct human impacts, such as sewage polluting coastal waters, these impacts have caused the loss of over 5000 square kilometres of seagrass – or 19% of the total area historically hosting seagrass meadows.

Despite the exceptional value and dire position of seagrass meadows, the support for seagrass conservation trails behind the conservation of their flashier coral reef neighbours. Riccardo Losciale and his team of marine scientists from James Cook University aim to rectify this by building an understanding of the key threats to seagrasses and the barriers to their conservation.

In recent research, the scientists focused on the 28 seagrass habitats across the globe that form a part of World Heritage sites. These sites are internationally recognised for their Outstanding Universal Value. As such, their permanent protection is of utmost importance. Until now, however, most seagrass research was confined to Europe, the east coast of the USA, and Australia, leaving knowledge gaps in many parts of the world.

The researchers used a risk assessment tool – the Climate Vulnerability Index – to evaluate the vulnerability of seagrass to the effects of climate change. Their method draws on the expertise of seagrass scientists and World Heritage site managers to evaluate the exposure, sensitivity, and adaptive capacity of seagrass habitats to key climate stressors. The seagrass habitats were separated into six distinct bioregions for the analysis to account for regional differences.

The results showed that almost all of the 28 seagrass habitats had moderate to very high levels of exposure to climate stressors. As such, many seagrass habitats are highly vulnerable to the effects of climate change. More than ever before, seagrass experts are in agreement that climate change poses severe threats for the future of seagrass habitats.

In particular, the rise in sea-surface temperatures were indicated as one of the top three stressors in four out of the six bioregions. Importantly, the results also illuminate that climate change and human activities act synergistically to impact seagrass habitats – the cumulative effects of both being worse than the sum of each individually.

In other research, Losciale and his team focused on residents living near the Great Barrier Reef. The iconic coral reefs rely on adjacent seagrass habitats. As such, any efforts to protect the reef must also consider seagrass conservation. Despite this, the study provides evidence that public perception is imbalanced in favour of the flashier and more charismatic coral reef habitats, with an overall lack of public awareness about the importance and vulnerabilities of the seagrass. This tendency to favour more attractive and appealing habitats has been dubbed the ‘charisma gap’.

While a significant proportion of the survey respondents had heard of seagrass, many lacked a clear understanding of its ecological functions and economic value. Many people believed that the ecosystem services provided by coral reefs were greater than those provided by seagrass habitats. Particularly, although a promising 75% of people believed in climate change, many mistakenly attributed the lion’s share of climate mitigation to coral reefs instead of seagrasses. Additionally, many people believed that climate change had a disproportionate detrimental effect on coral reefs, when in fact, seagrasses are equally at risk.

This imbalance extended to the respondents’ willingness to pay for seagrass conservation efforts. Overall, the coastal residents were eight times more likely to pay for coral reef restoration than seagrass restoration. However, the responses also demonstrated a promising willingness for restoration funds to be distributed across marine habitats, provided that communication about the use of the taxes is transparent and equitable. Where objections to marine taxes arose, these were predominantly based on a general mistrust in government. This highlights opportunities to improve conservation efforts by opening a dialogue between local government and residents and improving public trust.

Through their research, Losciale and his team paint a picture of extreme risk and potential promise for precious seagrass habitats across the world. To ensure the permanent protection of seagrass meadows, the ability of habitat managers to protect seagrasses from the effects of climate change must be improved. Working with local governments and communities to raise the profile of seagrasses could encourage the support necessary for successful conservation efforts.