Water pollution…are you familiar with it? Did you know that out of all the major Ocean issues, water pollution is not talked about much.
As a researcher in the marine mammal field, I’ve noticed several public perceptions that seem to persist throughout each city I visit and each demographic I talk to. Generally, people are really concerned about the dolphins in Taiji. People are also really upset about whaling. Sometimes people even share worries about unsustainable ecotourism. However, I’m almost never get asked questions about water pollution in the Oceans. This is especially alarming, because water pollution in the Oceans represents one of the biggest threats to marine mammals (whales, dolphins, and seals) around the world.
It is a complicated issue with multiple sources and many detrimental effects–most of which are not actually fully understood. This post is the first of a 3 part series where the issue will be broken down into the following sections: (1) Sources and Contaminants, (2) Ecology of apex predators like dolphins, and (3) What we can do to help. This post covers the 1st of the 3 parts: Sources and Contaminants.
There are many kinds of pollutants found in the marine environment globally, which include chemical compounds, oil-pollution derived substances, marine debris (including plastic), sewage-related pathogens, excessive amounts of nutrients that change the environment, and radionuclides. Most of the research published, however, represents work performed on chemical compounds such as organochlorines and heavy metals.
Organochlorines are used for a variety of industrial and agricultural purposes. The two most well-known are DDT and PCBs. DDT is an agricultural pesticide, while PCBs are used for a huge array of purposes, including inks, plastics, electrical transformers, and many others. These compounds are so toxic that they were both banned from use by the 1980s due to their apparent toxic effects. The ban, however, was only enforced in developed countries and even to this day these chemicals are still being used in third world countries.
Organochlorines severely damage vital organs including the brain and liver and also have a sterilizing effect on males. The effect of organochlorines on females and young is a bit more complicated and will be discussed more in the next post.
The three most common heavy metals in the scientific literature are lead, mercury, and cadmium. All of these elements do occur naturally in the environment at trace levels (i.e. small levels), but due to a variety of man-made industrial processes, levels in the environment are now much higher than they have ever been. The toxic effects of metals are varied but they, too, damage the vital organs like the brain, liver, kidney, blood, and bones.
In the next post I will discuss the effects of these pollutants in the marine environment, specifically on cetaceans and their survival in the wild. I will also discuss some interesting adaptations that some species have demonstrated to help them cope with surprisingly high levels of pollutants in their environment.