Conor Doolin
It is estimated that by 2050, seven in ten people will live in urban areas, and a 25-70% increase in food production will be required to meet an individual’s minimum calorie intake. As better occupation, education, and living opportunities are offered in urban cities, coupled with rising sea levels and land erosion, populations will be forced into more concentrated areas. Competing against increased global food production demand are the effects of climate change, which threaten to disrupt our global food supply. Over the past decade, scientific understanding of climate change has improved. To combat climate change, individuals have two options: adapt to the changing climate patterns or mitigate impending consequences. With global food demand and production projected to increase tremendously, mitigating climate change through sustainable and ecologically viable production systems is essential.
The production of animal protein for human consumption is associated with large releases of greenhouse gas (GHG). Land-based livestock production, such as cattle, poultry, and pigs, release 7.1 Gt of carbon dioxide (CO2), or 15% of annual global GHG emissions. GHG release from terrestrial livestock farming involves much more than the methane released as a byproduct of digestive microbial activity. It also includes the clearing of land for grazing, application of fertilizer, production of animal feed/fodder, and manure management. If one considers the robust supply chain that gets livestock from a farm to a local grocery store - one which includes transportation, cooling, heating, and ventilation,- GHG emissions from terrestrial livestock farming are even larger.
Terrestrial livestock is the biggest source of protein in the diets of United States citizens. Beef has the highest GHG cost per kg of protein, so reductions in beef consumption would have significant impacts on global food-based GHG emissions. To mitigate climate change, The United States must adopt new legislative and social paradigms and transition to diets with larger respect for sustainable food sources. One such strategy is oyster aquaculture. Aquaculture is the cultivation of aquatic plants or animals. Oysters once made up an important part of the diet in coastal cities of the United States. Native Americans and colonists consumed large numbers of oysters. In modern times, oyster aquaculture is done in two ways: Oysters are held in cages suspended above sediment or placed directly on sediment. Oysters do not rely on feed inputs from the farmer, but rather filter their food directly from the water. Oysters present an opportunity for an ecologically beneficial industry. Also, costs associated with transportation from farm to store are low as minimal pre-consumer processing or waste is associated with oyster production.
GHG emissions from oysters do exist but are negligible when compared to terrestrial livestock. When oysters respire and form shells through calcification, they release CO2. In aquaculture systems that utilize sediment raising procedures, where sediment is disrupted for the cultivation of oysters, GHG fluxes from the deposition of organic matter increase sediment CO2 and nitrous oxide (N2O) release. Oysters possess denitrifying microbes (microbes that convert nitrates to nitrogen) in the oyster shell biofilm which excrete small concentrations of methane, but altogether oyster GHG emissions are negligible. Through various GHG emission comparisons between terrestrial livestock and oyster aquaculture, it is estimated that oysters have roughly 0.04%, 0.09%, 0.25%, and 0.33% of GHG-cost emissions per kg protein of beef, small ruminants, pork, and poultry, respectively. It takes between 18-24 months to raise a market size oyster which is approximately 3 inches, or 7.62 centimeters. With modern meat manufacturing procedures that value steroid additives and unnatural supplementation, beef cattle reach market weight within 22 months. Although, one beef cattle requires two acres of land to feed, extensive financial investments in food, and contribute largely to GHG emissions.
Oyster aquaculture can provide a low GHG emission protein source relative to terrestrial livestock production. It is also adaptable and less intrusive to existing marine ecosystems when compared to other aquaculture practices. Oyster aquaculture is protected from storm surges, high waves, and regulates overall nutrient inputs better than other commercially available fish species. The largest combatants of the adoption of oyster production are a change in public perception of the safety and nutritional value of eating oysters, the scale and demand of oyster aquaculture systems, and the ecological consequences of ocean acidification.
References
Larsen, C. S. (1995). Biological Changes in Human Populations with Agriculture. Annual Review of Anthropology, 24(1), 185–213. https://doi.org/10.1146/annurev.an.24.100195.001153
Ray, N. E., Maguire, T. J., Al-Haj, A. N., Henning, M. C., & Fulweiler, R. W. (2019). Low Greenhouse Gas Emissions from Oyster Aquaculture. Environmental Science & Technology, 53(15), 9118–9127. https://doi.org/10.1021/acs.est.9b02965
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