Truffle-fried oysters and oyster soup have long been favorites in Hong Kong’s bustling restaurants.  Oysters have also been grist to the city’s industrial mill: the process of lime-extraction (which dates back to the Tang dynasty) deriving calcium oxide for use in building, boat caulking and agriculture by burning shells or coral skeleton.

Many believe that these myriad appetites of the city which boasts the highest concentration of ultra high-net-worth individuals in the world have caused the rapid decline of its famed oyster reefs which once stretched across an estimated 1,000 km of coastline in the Pearl River Delta area.

A study conducted by University of Hong Kong’s Swire Institute of Marine Science and environmental organisation The Nature Conservancy has shown the enormous potential lost when we lose our native oyster reefs. An individual oyster can, the 2020 study found, filter up to 30 liters of water per hour and 500 liters per day at summer temperatures (the metabolism of oysters, like all marine invertebrates, increases with temperature).

Oyster reefs also provide shelter for crabs and snails, nursery habitats for juvenile fish and feeding grounds for larger fish. They help in denitrification by removing excess nutrients, help seagrass recovery and reduce the resuspension (erosion) of fine sediment, improving water clarity.

Associate Prof. Bayden Russell, Associate Director at The Swire Institute of Marine Science, the University of Hong Kong and involved in the study, explains, “we’re discovering how abundant and widespread these reefs must have been in the region. The level of impact on them has been surprising.” 

The project was a community endeavour, Russell adds. “We deployed a few trial reefs in a couple of places, and that has only been possible because we have been working with the farmers and fishermen.”

The Nature Conservancy has worked on shellfish reef restoration involving local fishing communities in Australia, United States and New Zealand, identifying suitable sites for restoration, creating oyster reef bases and scattering these areas with baby oysters and mussels for the last twenty years, with a typical project costing around US$64,000 for 400m² of reef. The organisation is also helping struggling oyster farmers impacted by the COVID-19 pandemic (and concomitant drops in restaurant oyster consumption) by purchasing five million surplus oysters to be used to seed native shellfish reefs.

Marine Thomas, Conservation Project Manager at The Nature Conservancy, Hong Kong, says when restoring shellfish reefs it is important to understand what is left, how healthy it is and whether the reef is still reproducing in the water. Reef restoration projects such as this are therefore not possible in every context. Oysters, importantly, need something hard to settle on (substrate), even if it is a limestone rock or other oyster shell, to attach to and keep growing. “This then guides us with the kind of restoration method we need to apply,” she says. “In Hong Kong, which has plentiful shellfish larvae, we can undertake restoration wherever we find suitable substrates.” 

A mature reef takes five years to grow; however a trial reef, established under a fish farm in Hong Kong’s Tolo Harbour in 2019, has been colonised by a variety of sea life, including crabs and sea urchins (which are not typically found in the region). In other locations where The Nature Conservancy operates, restored shellfish beds have helped reduce flooding and improve coastal water quality. And that’s good news for our environment, as well as Hong Kongers’ dinner plates.

Author: Bindu Gopal Rao, The India Story Agency for Sacred Groves
Images Credit: 1. Kyle Obermann, all others The Nature Conservancy

The post The Hidden Heroes of Marine Ecology appeared first on The Sacred Groves.

When hurricane Delta hit the coast of Mexico on 7th October 2020, experts reckoned that repairing and replanting the ravaged coral colonies of the Mesoamerican Reef (MAR) and the coastline around Quintana Roo south of Cancun could cost about USD $800,000. Rapid response was critical as broken coral dies within weeks. But government funding, predictably, could take much longer to materialise. Conservationists and local businesses alike realised that the cost of not repairing the battered reef would be greater than the cost of restoring it, as the Mesoamercian Reef is second in size only to Australia’s Great Barrier Reef and home to 500 types of fish, 70 different corals, sea turtles and whale sharks. Yet, 80 percent of the living coral along Mexico’s Caribbean coast has been lost or degraded in the past 40 years due to pollution, overfishing, disease and increasingly extreme weather events. A simple and cost-effective solution came to their rescue: insurance.

A pioneering nature-based insurance policy purchased in 2019 by the Quintana Roo state government in conjunction with environmental NGO The Nature Conservancy (TNC) funded the efforts of Guardians of the Reef, a group of 80 trained snorkelers, fishermen, biologists, even local restaurant staff led by local diver Emanuel Quirago. They stabilised 1,200 affected coral colonies and removed storm debris from the beaches within 11 days. They also rescued and transplanted almost 9,000 broken coral fragments in artificial nurseries until they could be reattached to the seabed to regenerate new coral colonies. The work is ongoing and the guardians are poised to respond to future storm events if necessary.

The funds for the insurance policy came from the Coastal Zone Management Trust, set up by the state government with support from TNC and revenues were paid by beachfront property owners and hoteliers. A parametric insurance policy like this involves calculating pre-specified payouts depending on various potential trigger events – in this case, the payout varies according to wind strength. The restoration of these coral reefs, which attract over a million snorkelers and divers annually, has ecological and commercial benefits. Healthy reefs absorb 97 percent of each wave’s energy so they buffer the coast against storm damage and provide nurseries for breeding fish.

“Insurance plus government commitments paired with on-the-ground rapid response create the perfect formula to quickly repair critical coral reefs,” says Fernando Secaira, Mexico’s climate risk and resilience lead for The Nature Conservancy. TNC was able to enlist the participation of local businesses by making them aware that the health of this fragile coastal ecosystem was intrinsically linked to their economic success. “It’s a win-win and we look forward to identifying other parts of the world where this approach could work,” he says. They are exploring the feasibility of insuring reefs in regions like the Caribbean, Central America and Asia. Studies show that insurance policies like this could help protect coral reefs against natural disasters – perhaps to protect Florida reefs from future hurricanes and coral in Hawaii from marine heatwaves or coral bleaching.

Nature advocate and CEO of US-based fintech company Cultivo Dr Manuel Piñuela believes that this parametric insurance for nature-based projects will grow over the coming years: “We see innovation around insurance and reducing risk as a critical component to unlock investment into nature.”

Author: Anna Turns, The India Story Agency for Sacred Groves
Images Credit: 1. Daniela Zambrano The Nature Conservancy, all others The Nature Conservancy

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