National Aquarium Director Faults Gulf Damage Assessment

Touts Device That Bioaccumulates Like Fish Do
The U.S. effort to assess damage from last year's Gulf oil disaster is overlooking the impact of low levels of petroleum contaminants, the head of the National Aquarium's Conservation Center told senators Tuesday.
"The process is not using a methodological approach that adequately measures small quantities of petroleum contaminants which could have chronic impacts on aquatic biota," said Erik Rifkin, executive director of the National Aquarium Conservation Center, in testimony before the Senate Committee on Environment and Public Works' Subcommittee on Water and Wildlife.
The "grab sampling" methods now being used often report non-detects, Rifkin said, when tiny amounts of hydrocarbons are present, and they only measure concentrations at the moment the sample is taken.
Rifkin advocated the use of semi-permeable membrane devices that act like virtual fish. Developed a decade ago by the U.S. Geological Survey, the device:
is designed to mimic the parts of animals that cause bioconcentration. It is a long, flat, plastic tube containing oil. We call them "fatbags." The special plastic of the SPMD allows contaminants to pass through, like membranes of animal cells. The oil inside is similar to a highly purified fish fat. The contaminants dissolve in this oil just as they do in the fats of a fish.
When the SPMDs are put in the water and left for a month, they gather hydrophobic contaminants just as a fish would. We then collect the SPMDs and chemically analyze them for the contaminants.
Rifkin also advocated this type of sampling in testimony 11 months ago, he reminded senators. Since then the Aquarium has conducted an independent study, with Mote Marine Laboratory and Johns Hopkins University, to prove the value of the low-level hydrocarbon sampling. The study is still underway, but Rifkin said their findings so far support the use of virtual fish to produce "a far more accurate assessment of the nature and extent of chronic damages in the Gulf."
Alaskan fish, sea birds and sea otters showed prolonged effects from bioaccumulation of low levels of petroleum after the Exxon-Valdez spill, Rifkin said, including increased mortality, lower growth rates, decreased reproduction and compromised immune function.
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