Mercury Poisoning In Food Chains: It's Not Just the Fish at Risk

Almost everyone likes the sight of snow or a sunny rain shower. I mean it's just water, right? Calm, peaceful, and beautiful. But how would your opinion change if I told you that this atmospheric deposition could be just as harmful to us as the burning of fossil fuels and industrial discharge? Getting into our lakes and streams, mercury is causing major problems in aquatic life and food chains, including the top of the food chain (us humans). 

Creole Wrasse Fish swimming in shallow waters.

What is mercury and what are its effects?

Mercury is not just the two tiny letters you see in a box on a periodic table. Mercury can be found inside the earth's crust and thanks to it being a basic element, it cannot be created or destroyed. Found in rocks and deposits of coal, in its natural state, mercury in small amounts may be harmless to most humans, however, when its vapors enter our lungs, it can be lethal. 

How does mercury get into water sources? 

The organic chemical being found in coal results in the mercury-filled coal being used when fossil fuels are burned. The burning of oils, wood, and coal can all cause mercury to become airborne and consequently fall to the ground. This is not the only way that mercury travels, however. Being released into the air, mercury makes its way into precipitation cycles. Mercury makes its way to the ground with raindrops, hitting Earth's surface. After mercury mixes with snow and rain, it easily enters lakes, ponds, and oceans - and then, our fish. 

The cycle of how mercury travels throughout the environment and within bodies of water. 

What does this mean for our gilled friends?

When the mercury enters the water, anaerobic bacteria turn it into methylmercury. Then, the methylmercury enters fish through both water, taken in through their gills, and through their food. Mercury becomes bound in the tissue and muscle of these fish which then leads to major problems for them. The methylmercury continues to build in the fish's tissue which is an issue, as methylmercury is extremely toxic. The larger the fish, the more it eats and the longer it lives, giving the substance much more time to bioaccumulate. These predators eat smaller organisms that contain the substance which continues the spread of methylmercury in the food chain, a process known as biomagnification which increases with the trophic levels. 

This mercury poisoning has contaminated lakes all over the world, one of them being Lake Onondaga in New York just over 300 miles away from New Jersey. A recent study has shown that fish tested from about 300 streams across the US have traces of mercury inside them. The contamination of these waters does not limit its effects to just fish. Fish-eating birds have also been majorly affected by these toxins and it doesn't stop there.

Mercury: A Problem for Humans, too

As stated previously, mercury exposure in small amounts may be harmless to humans, but that is not the case for people who are at high risk, such as pregnant people and their unborn children. Since babies' nervous systems are developing in the womb, it is vital for them to have ideal growing conditions. Mercury exposure can lead to birth defects in babies' nervous and reproductive systems. Specifically, these defects can include the inability to speak, blindness, and brain damage in young infants.

Even if one is not put at such exposure as an infant, there is still a major threat of mercury exposure later in life. Breathing in or ingesting the toxic vapors can lead to major lung problems and damage the immune system. Additionally, other problems for children and adults include damage to the nervous system, kidneys, and liver. 

The risk that we humans face seems serious enough to effect change to decrease the levels of mercury in the environment. However, nothing significant is being done to help fix this serious problem.

Why The Problem is Worsening

The increasing temperatures that global warming has created are far from helping the problem that now millions face. Methylmercury can be passed down from generation to generation, being passed on to fetuses. Therefore, people in the world have trace amounts of methylmercury in their bodies because of its prevalence in the environment around us.  Along with the fumes being put into the air from burning fossil fuels, the rising temperatures of the world are thawing Arctic ice which has had mercury trapped in its midst for thousands of years. The melting of this ice then releases the mercury into the surrounding soil and water, killing the wildlife of the arctic. 

Photographer setting up a camera to capture the melting of arctic glaciers by the ocean.

The effect that pollution and mercury have on all organisms relates heavily to what we've learned about ecology this past year. The man-made climate change that has been increasing over time thanks to the burning of fossil fuels and other forms of chemical discharge all show how human impact is changing the environment at a global level, causing habitat change for animals who lived on the melting ice and the new diseases introduced, such as mercury poisoning. 

In order to help ourselves and the environment around us, there have to be major strides in how we get our energy and how much pollutants we spew into the environment. Fossil fuels are proving more and more harmful to our already weakening environment. 

A man eating a whole fish