Feeding the future with Shellfish

Low Trophic

There are sixty-four Sea Large Marine Ecosystems (LMEs) on planet Earth and three of the most productive are the California Current, Guinea Current, and the Arabian Sea.  All three are unique upwelling LME’s where KZO Sea Farms is the only company developing offshore sustainable shellfish mariculture projects.  

Seventy percent of the Earth is ocean and ninety percent of the ocean is “desert’ because there are no nutrients available for marine life food chain.  The nutrients are there but too deep to reach without natural upwelling, which occupies only .1 percent of the ocean surface but produce nearly half of the world’s ocean fish.  

The phenomenon of upwelling elevates deep offshore nutrients to the surface for the propagation of phytoplankton, which is the foundation of the bountiful marine food web, and the currency for the health of our oceans.  Phytoplankton are feed-stock for lower-trophic shellfish which could be the only sustainable ecological and economical solution for feeding a higher-trophic and malnourished future global population of 9 billion. 

Phytoplankton thrives under near shore summer conditions as single-celled algae supporting the base of the marine food chain.  The vast majority of marine life in coastal waters could not exist without these naturally occurring microscopic plants.  Nutrient rich waters, combined with long sunlight days, cause the phytoplankton to bloom.  The resulting abundance of phytoplankton becomes the natural food for filter feeding bivalve shellfish.  

Most marine animals and plants live in the top 120 feet of the water column.  When they die, their remains sink to the bottom.  In shallow coastal waters, the nutrients can be recycled from these highly productive areas.  But if the water is deeper than about 120-300 feet the remains sink below the euphotic zone, which is the uppermost layer of a body of water with sufficient light to enable photosynthesis.  This enriches the deep ocean water but the nutrients are unavailable for the propagation of surface dwelling phytoplankton.  Deep ocean nutrients can re-enter the food chain only in locations where the unique phenomenon of upwelling forces them up to the surface.  

This does not generally happen in warm and temperate regions of the oceans due to the density difference between the warm surface water and the cold deep ocean water.  As a result, most tropical and temperate oceans have low productivity.  However, in cold waters at high latitudes and in regions where currents bring cold polar water from the high latitudes, the ocean surface temperature drops to about 40 degrees Fahrenheit and its density is similar to that at the bottom.  The nutrient-rich deep water is then easily brought to the surface by turbulent mixing.   This upwelling phenomenon is restricted mainly to the west coasts of continents and is responsible for the high productivity of near shore waters producing the most productive ocean fishing grounds in the world.  The transport of nutrients to the euphotic zones explains why such a large percentage of global ocean natural production occurs in upwelling regions.  

The California Current LME, carrying water cooled by its passage through the northern latitudes, flows southward along the shore from the Washington-Oregon border to Southern California.  It has a surface area of about 2.2 million square kilometers.  It is one of the world’s five LMEs that undergoes seasonal upwelling of cold nutrient rich water that generates localized areas of high primary productivity supporting fisheries for sardines, anchovy, and other pelagic fish species. Beginning in March, prevailing westerly winds, combined with the effects of the earth's rotation, drive surface waters offshore.  These waters are replaced by deep, cold water that flows up over the continental shelf to the surface, carrying with it dissolved nutrients from the decay of organic material that had sunk to the ocean floor.  

The Gulf of Guinea is a Class I, highly productive LME characterized by seasonal upwelling off the coasts from July to September weakening from January to March. Seasonal upwelling drives the marine biological productivity of this LME, which includes some of the most abundant coastal and offshore fisheries in the world.  Sixteen countries border this LME, which covers an area of about 2 million square kilometers on the largest continental shelf in West Africa.  The cold nutrient-rich water of this expansive upwelling system extends up to 200 kilometers offshore from the coast.  

The Arabian Sea LME covers an area of about 3.9 million square kilometers and is also a Class I highly productive ecosystem.  It is characterized by seasonal upwelling off the coasts with intense upwelling from July to September weakening from about January to March.  The most stable, seasonal persistent front develops in the Gulf of Aden.  Seasonal upwelling drives the biological productivity of this LME, which like the Gulf of Guinea includes some of the most productive coastal and offshore waters in the world.  Upwelling fronts are similar to the seasonal evolution of the major upwelling zones off Northwest Africa and California Current System.