runoff

Just in time for spring breakers all over the country to hit the beach, springtime showers have massively increased, bringing tons of runoff into neighboring oceans. So what’s the big deal? Besides the nasty looking, murky agricultural runoff and lake/river overflow getting dumped into the ocean being a turn off for vacationing college students, there lies a bigger problem under the surface. All the rain and the runoff these storms cause could be seriously affecting ocean ecosystems. There have even been dead zones popping up in some areas due to algae that fertilizers seem to be cultivating, along with the other chemicals and waste being washed out into the ocean. As if oceans weren’t experiencing enough changes due to carbon dioxide increases in the atmosphere, springtime rains are adding even more unwanted chemicals to everyone’s favorite vacation destination: the ocean.

Rain, Rain, Go Away

For most of the world’s oceans, biological productivity is based on the supply of nutrients to the surface of the water, while storms, wind and tides bring up nitrogen and nutrients from farther below the surface as well. These nutrients promote the growth of algae, which is a naturally occurring food source for some other organisms living in the same ecosystem. However, not all of these algae blooms are “good guys” for their ecosystems. Some blooms can be toxic to other organisms and release poison, killing organisms in the vicinity of these “bad guy” algae plants. Here is the real kicker: fertilizers and other agricultural runoff, normally carried down from rivers or streams, seem to be feeding these “bad guys” and supporting their growth! Additionally, the chemicals and other runoff components themselves are harming ecosystems closer to the surface and shore. This pollution is affecting multiple species of fish and other organisms, as well as plant life. With an increase in spring rains and flooding, there is more and more runoff with nowhere to go. Naturally, most of the runoff flows into rivers and streams, but these rivers and streams often then in turn flow into oceans. Agricultural runoff may seem like it would be many miles away from most oceans, but the topography of most areas helps to sneak it down through rivers. And then BAM! The ocean is affected from half the country or in some cases almost a continent away.

From the Sky to the Sea

Now, naturally we can’t control the weather and stop heavy rains from falling. However, agriculture and industry play a large part in the development of weather and climate changes. Such human activities increase the amount of carbon dioxide, CO2, in the atmosphere, as well as other gases or emissions. Interestingly enough, the amount of rainfall in certain areas is affected by these emissions. They hold onto moisture and finally they become heavy enough to fall as precipitation. Thus, runoff is increased as the amount of precipitation is increased. Additionally, the CO2 that is released by agriculture and industry is then absorbed into oceans as well. As the amount of CO2 increases in the atmosphere, the oceans take in more and more of this gas, about 25% of what is in the atmosphere. The absorption of this CO2 is literally changing the chemistry of seawater!

pH

The Chemistry?

As the amount of CO2 absorbed by the ocean increases, the pH of the ocean decreases. You may be asking: What is pH? The pH is the measure of how acidic or basic water is. To put this into a quantitative range, there is a scale that goes from 0 – 14, with 7 being in the middle and therefore neutral. A pH of less than 7 indicates an acid, whereas a pH of higher than 7 indicates a base. From a scientific standpoint, pH can be described as the measure of the amount of free hydrogen and hydroxyl ions found in the water. As concentrations of CO2 increase in the ocean, the chemistry of the water changes because the pH is decreasing, making it more acidic, and affects potentially every ocean dwelling organism. For example, organisms with that form hard, calcium carbonate shells, or calcifiers, such as clams and crabs may be impacted by the acidity of the water they live in, seen in slower growth rates and decreased health. The impact doesn’t end with shelled organism either. Because of the effects on these organisms, entire ecosystems are altered and can change marine food chains and patterns. Taking things closer to the surface, a decrease in mussels and barnacles, also calcifiers, will lead to a decrease in seabirds and other marine mammals that live off these organisms. A domino effect begins and this process is hard to combat. The effects of ocean acidification, the lowering of the pH due to CO2 intake, are massive and widespread.

All these problems are unfortunately a result of the way we live our lives as a society today. It is amazing to see the effects down under the surface and to think about the changes marine organisms are starting to feel. It is often times hard to keep in mind the effects we humans have on the ocean and all the creatures that live there. It is definitely something to think about as you head off to the beach for break! Don’t take those pesky seagulls and crabs for granted. Happy Spring Break!

 

Resources:

http://www.ucsusa.org/global_warming/science_and_impacts/impacts/heavy-flooding-and-global-warming.html#.VvClSGQrK8p

http://www.pmel.noaa.gov/co2/story/Ocean+Acidification

http://sanctuaries.noaa.gov/science/sentinel-site-program/farallones/climate-change-ocean-acidification.html

http://www.earthmagazine.org/article/shell-shocked-how-different-creatures-deal-acidifying-ocean

http://news.stanford.edu/news/2005/march16/gulf-030905.html