New research from SFU’s criminology department shows that the level of oxygen in the ocean has a significant impact on the decomposition of submerged bodies.

The study involved the three-year observation of three underwater pig carcasses in the Saanich Inlet, submerged at a depth of 100 metres.

Carcasses placed in the water were scavenged after about a month, when dissolved oxygen levels were “tolerable,” but when the inlet was anoxic, or without oxygen, the pig lasted many months before all soft tissue was consumed.

Gail Anderson, an SFU professor of criminology, led the study, with fellow SFU professor of criminology Lynne Bell as a co-author. Bell examines the effects on the bones remaining after ocean scavengers, like shrimp and crabs, have done their work.

The underwater observation technology, Victoria Experimental Network Under the Sea (VENUS), enables researchers to watch a live video feed of the carcasses, and frequently measures the level of dissolved oxygen, temperature, salinity, density and pressure in the water.

“Saanich Inlet is hypoxic (deficient of oxygen) most of the year and anoxic (without oxygen) at some times,” explained Anderson.

These findings also show that this shift in oxygen levels dictates which scavengers are in the area at a given time of year. When larger scavengers are driven away by low oxygen levels, scavenging is left to smaller creatures, such as Squat lobsters. However, these animals can’t break through the skin as easily and have a harder time scavenging the body.

“This gives us a better understanding of what happens to bodies in such waters,” said Anderson.

“These studies have provided valuable information for underwater death investigations.”

– Gail Anderson and Lynne Bell, study authors

In the published study, they explain the relevance of their findings to crime-solving efforts: “These studies have provided valuable information for underwater death investigations, describing conditions of bodies over time in hypoxic and anoxic environments.”

It continues, “These data will be valuable in forensic investigations involving submerged bodies, indicating types of water conditions to which the body has been exposed, identifying post-mortem artifacts and providing realistic expectations for recovery divers and families of the deceased.”

This study is one in a series of pig carcass deployments at various depths and locations. Anderson and Bell’s latest deployment can be viewed via VENUS online at venus.uvic.ca.

The duo’s next step forward in this research will take them east of Vancouver Island to Barkley Canyon.