Insects Provide Clues About Bodies Underwater

October 22, 1997

Aquatic Invertebrates Provide Clues About The Case History Of Submerged 'Bodies'

Niki MacDonnell says the eight rotting pig carcasses she'll pull from streams and lakes in local forests next month hold important clues about deaths that occur in freshwater.

For the past year, the Simon Fraser University graduate student in pest management has made routine visits to the clothed and submerged 'bodies' to study the life cycles of insects that colonize on them - everything from aquatic bugs to earthworms and even clams.

Insects may be able to tell how long a body has been at a certain location, and whether it has been moved -vital information in determining the circumstances surrounding water-related deaths.

With virtually no research in the field to draw on, Macdonell says pathologists are "basically taking an educated guess" when they estimate time of death in such cases.

Macdonell examined 200 cases of freshwater deaths in B.C. in 1995/96, and now wants to see if what happens to the pigs is what happens to humans.

"I'm trying to find out whether we can use some of these invertebrates to indicate a time line in deaths," says Macdonell. "It doesn't appear we'll be as accurate with these invertebrates as with those occuring on land. So little research exists that anything we learn will help."

Macdonell identified more than 50 species of invertebrates and is now piecing together their activity patterns. She's found that populations are different between streams and lakes, for example, so determining where death occurred, if it's in question, is possible.

Some aquatic insects are unpredictable, while others appear to be seasonal. "Unlike terrestrial insects, they may have other reasons for attaching themselves to bodies," adds Macdonell. "Bodies are a nutrient-rich source, but their decomposition and shape also make for great habitat."

Macdonell, who wants to be a coroner, says the research will be useful, given the high number of water-related deaths in B.C. It's also groundbreaking. The first study of a body decomposing underwater took place in Tennessee only three years ago. No research has been done in Canada. In fact, Macdonell planned to remove her pigs months ago, figuring they would have decomposed by then. "We're still learning about this process in underwater situations," she says.

Fascinated by forensic research as an undergraduate, Macdonell connected with SFU forensic entomologist Gail Anderson through the Internet. Anderson, who studies insect life cycles on murder victims' bodies, is well-known for assisting with local murder investigations. Her research includes studies of insects on clothed pig carcasses which have been buried or partially buried.

Macdonell is also helping Anderson teach a course in forensic science, offered by the school of criminology. It's proving there are many who share Macdonell's fascination - the class has 85 students and a waiting list.
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Simon Fraser University

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