A Basic Food That’s Battling Climate Change

Within the world’s pots and pans lies a potential catalyst for dietary revolution, a humble yet power packed food source that has frequently been overlooked. This natural protein provider, abundant with essential nutrients, can cater to the nutritional demands of almost a billion people among our planet’s most vulnerable demographics. It presents an opportunity to shift away from high intensity protein sources like cattle meat, offering rich prospects of enhancing the environmental and social landscape.

This game changing food source births from creatures that demand neither food, antibiotics, or farming chemicals. They play an active part in carbon sequestration and contribute to ecosystem preservation by purifying their aquatic habitats, thus heralding the underappreciated yet vital domain of bivalves.

Despite not boasting the allure of their fishy neighbors or the mesmerizing enigma of deep-sea octopi, this modest family of shell dwellers, encompassing mussels, clams, oysters, and scallops, have cemented their societal roles as filter feeders in our oceans’ biological makeup. They sustain themselves silently on the organic micronutrient filled waters around them. Their unassuming existence does not diminish their immense potential. As the globe ventures to nourish an ever expanding populace while lessening environmental impact, an increased incorporation of these shellfish into our meals could be the answer.

“Bivalves harness the ability to supply humans with food that is simultaneously nutrient dense and environmentally sustainable,” explains David Willer, a renowned zoologist at the University of Cambridge.
These shellfish can address many global food quandaries by offering a protein punch surpassing that of most meats and crops and brimming with vital omega 3 fatty acids and micronutrients such as iron, zinc, and magnesium. This is crucial in combating childhood malnutrition as these nutrients directly support development. An added bonus? The planet also gets to benefit from augmented bivalve consumption. These creatures, whether wild harvested or cultivated offshore and along coastlines, leave minimal environmental footprints compared to mainstream sources of animal protein.”

“Meat and fish impose a greater environmental burden compared to plantbased food,” Willer mentions. “Yet the environmental implications of bivalve aquaculture are even less severe than multiple terrestrial crops, considering the greenhouse gas emissions, and land and water usage.” As animal protein production notorious for its carbon contribution, largely because of animal feed production, use of fertilizers, and methane emissions from the animals themselves, this insight could potentially steer environmentally conscious dietary choices in a new direction.

The environmental impact of producing a ton of beef amounts to the generation of 340 tons of greenhouse gases while producing a ton of bivalve protein results in only 11 tons of emissions. While these numbers might be generalized globally and do not account for the different methods of beef production, the comparison isn’t limited to cattle. The fish of choice in developed countries, salmon, requires 5 kg of wild fish feed to yield 1 kg of salmon. “If a quarter of the protein derived from these carnivorous fishes was substituted with an equivalent amount from bivalve aquaculture, we could prevent 16.3 million tonnes of CO2 emissions every year. This is tantamount to halving New Zealand’s annual emissions,” declares Willer.

Eutrophication, an environmental issue of global concern, occurs when nutrient runoff into water bodies triggers excessive, sometimes toxic, algal growth or “algal bloom”. This is often due to the leaching of excess fertilizers from agricultural land, or industrial and urban wastewater seeping into the soil and eventually into the water bodies. The sudden influx of nutrients is capitalized upon by the algae, causing them to proliferate and cover the water surface. In extreme cases, this could devastate marine ecosystems by blocking sunlight, hindering plant growth, and depleting oxygen levels, consequently leading to wildlife mortality.

The Eutrophication Potential serves as a standard metric to evaluate how various activities detrimentally affect water bodies. Bivalves, in contrast to other farmed fish, boast a negative impact as they feed on and thereby reduce the surplus algae and other organic particles, effectively maintaining the cleanliness of waterways and oceans. By doing so, bivalves shield aquatic ecosystems from eutrophication’s harmful effects.

This played a pivotal role in solving a pressing issue back in 2010 at the UK’s Liverpool Docks. Following the shutting of flood gates after the decline of the Manchester Ship Canal, eutrophication of the harbor waters was observed, and the use of bivalves proved to be a major part of the solution.
According to Antony Knights, a marine ecologist at the University of Plymouth, “A single mussel has the capacity to filter 1.75 litres of seawater in an hour. Given their colonization density of almost 500 mussels per square meter, their beneficial impacts on the environment manifest swiftly.”
Knights recounts, “Through reintroducing mussels and timely reopening of the floodgates, algal blooms in Liverpool Docks were eradicated. The eutrophication problem was solved without employing any environmentally intrusive methods.” He views this as a sterling example of mussels offering “ecosystem services”, a term describing nature provided biological functions benefiting human beings, with mussels and their bivalve brethren playing a crucial role in this contribution. Mussels serve as pivotal elements in marine ecosystems by enhancing biodiversity in their capacity as ecosystem engineers. Knights elaborates, saying, “The reefs they form become a habitat for other marine creatures, ranging from barnacles and seaweeds to serving as nursery grounds for fish.”

This invaluable ecosystem service is leveraged globally by initiatives such as World Harbour Project. This international project aims to stimulate biodiversity on parse harbour walls worldwide by introducing bivalve colonies. These colonies serve as habitats for many other species and amplify their environmental contributions through their innate filter-feeding activity.

However, this ecological niche of bivalves poses a paradox. As filter feeders, they consume everything available in the water around them. This indiscriminate feeding pattern could pose an issue, given the somewhat uncommon way we consume such food, as it suggests the potential for harmful substances to end up within them.

Rachel Hartnell, a seafood safety scientist at the UK Government’s Centre for Environment, Fisheries and Aquaculture Science (Cefas), illuminates the unique feeding behavior of these creatures. “Bivalves essentially embody the attributes of their surrounding environment,” she says. This implies that these organisms can concentrate harmful microorganisms (often from agricultural runoff or sewage), toxins (stemming from bacteria or naturally occurring algae), and chemicals present in the water. Hartnell warns, “This potentially poses a threat to human health, particularly given how we tend to consume bivalves—mostly raw or lightly cooked, and including the gut.”

To mitigate this risk, she advocates for a thorough understanding of the hazards, assessment of the harm, and implementation of robust programs to manage any risks prior to their arrival at consumer plates.
However, if these risks are well-managed, bivalves could significantly enhance nutrition and bolster GDP in developing countries due to their superior export value compared to conventional fish species. The practice of bivalve farming could also be a catalyst for gender equality in coastal communities. Given the typical proximity of these farms to the coast, women can find a balance between earning an income and fulfilling childcare responsibilities, an opportunity usually not afforded by offshore fishing.

These promising economic benefits have compelled organizations like the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) to champion bivalve farming, particularly among more vulnerable nations. They do so through training programs in association with Cefas, as Esther Garrido Gamarro, a Rome-based fisheries officer with the FAO, explains.

“With the WHO, we initiated guidance on bivalve sanitation projects in places like Angola, Madagascar, Mozambique, and Namibia, and organized a workshop catering to 15 African nations in November 2019,” she states. Gamarro is looking forward to expanding the initiative to Asian and Pacific nations that have yet to fully tap into this sector, in the near future.
Harvesting bivalves’ unique filtering feeding mechanism to our advantage opens up new potential pathways: ‘vitamin bullets’ for shellfish, a novel technique developed by Willer and his research collaborator David Aldridge, enhances bivalves into nutrient-dense powerhouses to combat malnutrition.
“We devised a method to embed nutrients within a feed that appeals to bivalves,” explains Willer. Remarkably, oysters fed with merely 3% vitamin A and D microcapsules displayed elevated levels of both vitamins in their tissue within just eight hours. Consuming even just two servings of such vitamin-infused bivalves can supply the recommended dietary allowances (RDAs) of both vitamins.

“With more than two billion people worldwide plagued by micronutrient deficiencies, upscaling this technology and its application to other bivalve species, like clams and mussels, can offer a cost-effective and highly sustainable means to address global nutrient deficiencies,” urges Willer.
Globally, an estimated 1.5 million square kilometers (579,000 square miles) of coastal area makes for potential bivalve cultivation grounds. If only 1% of this potential is tapped, Willer suggests it could yield enough bivalves to meet the protein needs of over a billion people.

While the taste of bivalves might not suit everyone and culinary adventures with them might seemingly daunt some, a reconsideration of their potential could be overdue. The environmental benefits offered by these humble filter-feeding animals are commendable. Their nutritious value and potential empowerment they wield in their shells should inspire us to give them a second chance. The takeaway here is the undeniable and untapped potential these unpretentious aquatic entities hold.