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Voyage of the Odyssey Chief Scientist- Dr. Celine Godard
Photo: Carrie Newman

August 7, 2001
The Toxicant Build-up
  Real Audio
  28k   64k

Log Transcript

This is Genevieve Johnson. The Odyssey and her crew are currently making their way through the Coral Sea on route to Port Moresby, our last port of call before heading to Darwin, Australia. We are joined by Dr. Celine Godard who is onboard the Odyssey for the next two months. Celine is the Chief Scientist of the Ocean Alliance program the 'Voyage of the Odyssey' and has a Guest Scientist appointment at the Woods Hole Oceanographic Institution as an Environmental Toxicologist. The Odyssey is now in the second year of its five-year global voyage, designed to gather the first ever base line data on the levels of synthetic contaminants or toxicants in the world's oceans. In addition to the toxicology study, the Odyssey crew also gather bioacoustics data and skin samples for genetic analysis. Celine oversees the toxicology program, which includes the collection of data on board the Odyssey and she is currently analysing the tissue samples gathered so far.

Celine explains the toxicology program in detail.

Dr. Celine Godard:

The terms toxicants and toxins both refer to toxic substances. But, toxins are natural products such as the ones found in poisonous mushrooms, or in a snakes' venom. Toxicants are man-made products, artificial products introduced into the environment due to human activity; examples are industrial waste products and pesticides.

There are several reasons why the Ocean Alliance is using sperm whales as an indicator species to the health of the world's oceans. One very practical reason is that sperm whales can be found in all of the world's oceans, and therefore, it is a species that can be studied worldwide. Another reason is that sperm whales are mammals like us humans, so we do share several biological and physiological characteristics with them. In that respect, they are a relevant species in which to study the impact of environmental pollution. Sperm whales are also a good indicator species because they are exposed to ocean pollution throughout their life and they do have a relatively long life span. They also have a high percentage of fatty tissue in their body, sperm whales have a layer of fat called blubber just under their skin. Now most toxicants that are persistent in the environment are chemicals that accumulate in fat tissue. What this means for the whale is that the longer it lives, the longer it is exposed to pollutants and more toxicants end up accumulating in the whales body. This is a process called bioaccumulation. In addition to bioaccumulation, sperm whales are also subject to biomagnification.

What is biomagnification? Biomagnification refers to the increasing amount of chemicals found in animal species as you move up the food chain. For example, if a shrimp were to contain, lets say, just 1 unit of chemical and a fish eats 10 of those shrimp, it will have eaten with its prey about 10 units of toxicants. If a bigger fish eats 10 of the smaller fish it will end up with 100 units of toxicants in its body. This process repeats itself up and up the food chain with the top predator such as the sperm whale, subject to accumulating very high amounts of toxicants.

So you may be wondering what the implications of this study are for humans? The Ocean Alliance is using the sperm whale as an indicator species for the overall health of the oceans. Humans depend on the ocean and on marine life in many respects. It's a critical source of food for one, but tourism and recreational activities, for instance, are also of great economic value. So, it is important to assess whether pollution is posing a threat to ocean health.

Log by Dr. Celine Godard & Genevieve Johnson

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