How Japan’s Nuclear Crisis Might Affect Whales And Dolphins

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Japan’s attempts to control the damaged nuclear reactors at the Fukushima plant by using sea water hopefully will succeed in preventing a complete disaster, but the price paid both to the nearby marine life and to the people of that battered country will be huge and long lasting.  Unfortunately, the runoff of millions of gallons of contaminated water cannot be scrubbed before it flows back into the ocean, and what happens to that water is very complex –  as reassuring as it may be to think that the radioactive waste is immediately diluted in the vast seas, that is really not what happens.  Instead, much of the contamination is likely to be deposited in the sediment of the shoreline, and to be transported along the coast.  Depending upon how warm and salty the runoff is, masses of the water may be able to travel huge distances relatively undiluted and unmixed, to be absorbed by tiny planktonic creatures before working it’s way up the food chain to whales and dolphins.

The warm Kurashiro Current travels along the east coast of Japan and tends to meet the colder north Pacific water near the region of the Fukushima plant.

The processes at work in the ocean are so complex that even computer generated models can’t predict small scale events with certainty, but there are some basic principles that guide scientists, and for an easy to understand summary of those principles you might check here.
Near Japan, the warm Kurashiro current transports water from the south  until it runs into the cold northern water where  cooling begins.  The Fukushima plant is located where the two masses of water meet, helping keep most offshore contamination away from major urban coastal regions, but the present unforeseen highly contaminated near-shore runoff is not immediately transported to where those currents operate.
Assuming that the runoff is both warmer and saltier (due to evaporation) it will tend to mix and warm up the water in the immediate area, and changes in both temperature and salinity can be crucial to marine life.  This in turn affects how much and what types of the radioactive isotopes get taken up in the sediment and the creatures that live there before moving up to the 21 species of whales and dolphins found in the Sea of Japan alone.
Making the situation even worse is that Japan is heavily invested in fish and shellfish hatcheries, and produces everything from crabs to salmon in mass quantities, often with several species produced in the same hatchery.  Many of these hatcheries are vulnerable to fallout and/or pump sea water into holding tanks. The organisms raised there are released into the environment at various life stages, and the different life stages again take up isotopes at various rates, and further disperse into the marine environment where they can be eaten by bigger fish.

Japan depends heavily on fish and shellfish hatcheries.

The radioactive isotopes from the runoff may quickly move up the food chain in the local marine environment, leaving the fish-eating (resident type) orcas and other dolphins highly vulnerable to fairly immediate exposure as well as long term consequences.  Gray whales, which eat by scooping up the bottom sediment to filter out the shrimp-like organisms they favor, are possibly at the highest direct vulnerability.
Add the consequences of the fallout from the air in the region (which will be immediately taken up by plankton) and the effects are compounded.
Whale tissue, already highly contaminated with heavy metals and toxins, will become even more dangerous to eat and hopefully people worldwide will reconsider their policies towards hunting these animals. Many species migrate long distances, so it is difficult to be sure that a whale taken in one part of the world was not exposed to radiation in another – even the resident type orcas off the coast of Japan are believed to travel a thousand miles or more to more southern latitudes (based on the presence of unique ‘cookie cutter’ shark bites).

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