Photo: Wikimedia Commons.
The Common Snapping Turtle, Chelydra serpentina, is a common dweller of inner-city wildernesses, especially in rivers and shallow lakes.
Snapping turtles typically live about 30 years in the wild, which is an unusually long life span among species of urban wildlife. This, combined with their opportunistic, omnivorous diet (snappers are important aquatic scavengers) means that urban turtles' fatty tissues end up absorbing a lot of toxic substances from their environment.
This Canadian research paper analyzed turtle eggs at various sites around the Great Lakes, including in so-called "Areas of Concern" like the Detroit River and the Hamilton Harbor complex southwest of Toronto. From the abstract:
PCBs, organochlorine pesticides and dioxins/furans in snapping turtle eggs and plasma (Chelydra serpentina) were evaluated at three Areas of Concern on Lake Erie and its connecting channels (St. Clair River, Detroit River, and Wheatley Harbour), as well as two inland reference sites (Algonquin Provincial Park and Tiny Marsh) in 2001–2002... Dioxins appeared highest from the Detroit River. The PCB congener pattern in eggs suggested that turtles from the Detroit River and Wheatley Harbour [sites] were exposed to Aroclor 1260... Although estimated PCB body burdens in muscle tissue of females were well below consumption guidelines, estimated residues in liver and adipose were above guidelines for most sites.Even more interesting, a short blurb on snapping turtles from the book Concrete Jungle, edited by Mark Dion and Alexis Rockman (Juno Books, 1996) asserts that
In some areas, when the turtle dies it must be treated with toxic waste protocols.The long-lived snapping turtle: the fatty palimpsest on which the toxic legacies of our lakes and rivers are chronicled.