Beaches in several counties on Florida’s Atlantic Coast are currently closed due to the presence of slimy, malodorous and most importantly toxic algae. The algae growth comes from nutrient laden water being released from Lake Okeechobee to prevent flooding. For the back story read on.
Thomas Malthus was a English cleric who in 1798 published an essay which suggested that human disaster loomed due to over population. He postulated that population grew logarithmically [1,2,4,8,16…] whereas food production only grows arithmetically [1,2,3,4,5…] Malthus predicted famine and starvation were the only possible outcomes without controlling population growth.
The Malthusian Catastrophe of course didn’t come about. Although population is growing logarithmically agricultural practices have been able to sustain burgeoning human populations. Improved tools, irrigation, mechanization, fertilizers, pesticides,plant breeding and ever larger farms averted the catastrophe.
An important agricultural innovation was called the Green Revolution of the 1950s-1960s. Food production was increased by careful selection of plant cultivars which responded favorably to large increases of Nitrogen and Phosphorous fertilizers. Application at rates far above what a crop could actually absorb did result in increased production, but resulted in fertilizer run-off. Increased profits from the crops offset the wasted fertilizer.
But everything goes somewhere. The excess fertilizer washes off the farmland and into adjacent low areas to rivers and lakes, and ultimately into the oceans. Just as the fertilizer increases crop production in farm fields, it increases algal growth in the rivers and lakes.
The Atlantic beaches in South Florida are being fouled with algal blooms from water draining from Lake Okeechobee. The fertilizer laden water is the result of run-off from sugar cane fields which have replaced much of the Everglades.
Besides the inconvenience and costs associated with lost tourism dollars, there is significant secondary environmental damage. After an algae bloom comes an algae crash. As the algae dies off it decomposes aerobically. That means it consumes the Oxygen in the water. The same Oxygen that all the animals require, from the simplest aquatic insects up to and including all the fish.
In certain locales there are “dead zones” with little if any animal life. All the coastal areas of the US, including the Great Lakes, are plagued by dead zones at the mouths of major rivers. They are know scientifically as hypoxic (low-Oxygen) zones and range in size from less than a square mile to over 25,000 square miles. The largest is essentially all of the Baltic Sea. The hypoxic zone at the mouth of the Mississippi is about 7,000 square miles
Around the world there a several hundred of these sterile areas. We have averted the Malthusian Catastrophe for us, but created a catastrophe for the native flora and fauna of the planet.