Guest Blog By Lydia Ball – When the U. S. Navy sent the Trieste deep boat to the Mariana trench in 1960, it was the first time that humans had reached the deepest part of the ocean. The ocean floor was covered with silicon-based algaes, known as diatoms, and Jacques Piccard, a crew member, described it as “snuff-colored”.  Since then, technological advances have allowed for further exploration with more scientific rigor. In 2012, James Cameron made the second manned dive to the depths of the Mariana Trench. A flat, desolate landscape, seeming sparsely populated except for small shrimp-like creatures swimming before him as he collected geological and biological data.

“How do you stay positive when so many turtles are dying on a daily basis”? asked one of the Earthwatch volunteers. I paused for a second and contemplated a contrived answer. But then I told her the truth: “I cry myself to sleep most nights”, I said softly.

The massive earthquake and subsequent tsunami that hit Japan in March 2011 killed thousands of people, destroyed many coastal villages and caused a meltdown at the Fukushima nuclear power station.  When the reactors overheated, radionuclides were released into the atmosphere and surrounding land and water. This contaminated farm animals like cattle and local seafood. A recently published study “Pacific bluefin tuna transport Fukushima-derived radionuclides from Japan to California” by Drs. Madigana, Baumannb and Fisher found that radioactive contamination has crossed the Pacific Ocean. Pacific Bluefin Tunas are a large, pelagic fish, growing over 900 lbs, which spawn in and around Japan. Some young Pacific Bluefin Tuna then swim or migrate across the Pacific Ocean to feed in waters off the US west coast, and swim back again after a few years to spawn. The study mentioned above found that Pacific Bluefin Tuna migrating from Japanese waters after the nuclear meltdown occurred had unnaturally high levels of radioactive cesium isotopes when they were caught in Californian waters. Although contaminated, the level of radioactivity in the tuna is considered to be well within safe limits and thus does not pose a threat to people who eat it. It does highlight, however, that the seafood we eat often originates from distant shores where they are exposed to local events.