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The Damaging Effects of Fertilizers on Marine Ecosystems

The Damaging Effects of Fertilizers on Marine Ecosystems

Written by Leisure Pro Staff
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Published on February 14, 2020
algal bloom in a marine ecosystem

Farmers often use fertilizers when planting their crops as these substances help many fruits and vegetables grow. While they’re beneficial to crop growers, the toxic substances found in many fertilizers can lead to negative organic reactions.

People often consider the harmful effects of toxic substances on terrestrial species. However, what many people do not realize is that terrestrial fertilizers can also be very damaging to marine ecosystems. With these facts in mind, let’s take a closer look at the dangerous effects of fertilizers on aquatic environments.

How Do Fertilizers Make Their Way to Marine Ecosystems?

small algal blooms floating on freshwater

Fertilizers reach different marine ecosystems through a phenomenon known as runoff. When rainfall, irrigation, and snowmelt cause more water to enter the soil than it can absorb, the excess water will run off the land and into nearby bodies of water. The contaminants found in pesticides and fertilizers are often carried along in this drift, eventually making their way into the ocean. 

How Does Fertilizer Runoff Affect Water Sources? 

aerial view of a lake with algae and weeds in the water

Contaminates Drinking Water

Nitrogen fertilizers can create high concentrations of nitrates in water sources. Nitrates can leach easily into groundwater since they don’t absorb into soil materials. While nitrate in itself isn’t toxic to animals, it can cause a disease known as nitrate poisoning when it is found at high concentrations. 

High levels of nitrate pose a danger to livestock, humans, and other mammals. Drinking water loaded with nitrates can lead to a disorder known as methemoglobinemia, which results in nausea, dizziness, blue-colored skin, and other symptoms. Nitrate consumption also interferes with the oxygen uptake in the circulatory system in humans and livestock.

How Does Fertilizer Runoff Affect Marine Life?

dead fish on the sand

Oxygen Depletion

Commercial fertilizers release nutrients as they enter surface water. These nutrients stimulate microorganism growth and reproduction, reducing the dissolved oxygen found in marine ecosystems. Fish and other aquatic species suffocate when their habitat doesn’t have enough dissolved oxygen in surface water. In fact, dead species can make water quality poor and produce unpleasant odors.

Algal Blooms

Fertilizer nutrients can cause algal blooms. Marine ecosystems usually contain some of these nutrients, which assist in marine plant growth. But some algae grow bigger when strong nutrient levels discharge into the water. Depending on the affected algae type, these growth explosions can be classified as red or brown tides.

Blooming algae releases harmful toxins. In normal levels, these toxins would not have much effect on marine creatures. However, in such large amounts, these toxins can easily poison many different types of marine life.  In addition, algae require a great deal of oxygen in order to grow. Because of this, the water may become oxygen deprived, suffocating other marine creatures. Sometimes, the algae and its toxins are so overwhelming that an ecosystem is essentially shut down. Whole areas may become dead spots—places where normal marine life can no longer thrive or live at all.

Dead zones show up seasonally near most major river mouths. All these threats stem from cultural eutrophication, a process that occurs when human activity changes nutrient levels in water basins. The phenomenon causes marine environments to deteriorate over time.

Algae blooms may decrease with time, but an affected ecosystem can take years to return to its former, healthy self. These lasting, damaging effects can also harm neighboring ecosystems that rely on the various fish and crustaceans to survive.

What Causes Fertilizer Runoff?

a small snapper swimming over algae underwater

The following situations mainly cause fertilizer runoff:

  • Overfertilizing
  • Fertilizing at the wrong time of the year

Applying fertilizer impulsively results in overfertilization. While overfertilization often happens in farms, it can occur in home gardens as well. Even when the right amount of fertilizer is applied, it can still harm the environment when it is not applied at the right time and location, or in the correct form. 

While all the effects we’ve mentioned here exist in marine ecosystems, scientists have been conducting many studies on the actual effects of fertilizer runoff and fertilizer pollution on these areas. And as the evidence piles up, more and more scientists now think that toxic runoff is a real problem. Experts even think that national and local governments should implement certain regulations in the future for greater protection of marine life.

Leisure Pro Staff

Leisure Pro Staff

Marketing Director for LeisurePro