Trace Elements Checklist

• Found at multiple sites in the estuary
• Occur naturally and from industrial activities
• Bioaccumulative
• Have sublethal effects on salmon behavior and health
• Toxicity can be synergistic (more than the sum of the parts)

What Are They?

Trace elements are metals and similar substances that are toxic at fairly low concentrations and for which organisms have little or no biological need. Examples include arsenic, copper, chromium, lead, mercury, and nickel. Trace elements occur naturally, but they also have a variety of industrial uses.

Most trace elements bioaccumulate in fish and wildlife.

Trace Elements in the Estuary

Trace elements such as arsenic, chromium, copper, lead, and nickel are present in the water in the Columbia River estuary—many of them at sites throughout the estuary. In LCREP (2007), concentrations of most trace elements were found to be higher near the mouth of the Columbia River than at upstream sites.

Impacts in the Environment

Several trace elements can be toxic or have sublethal effects on salmon behavior and health:

• Arsenic—Reduced growth, disrupted smoltification, physical/developmental abnormalities
• Chromium—Disrupted feeding, reduced response to stimuli, immune suppression, reduced growth, disrupted reproduction, cellular damage
• Copper—Difficulty avoiding predators, less frequent spawning, reduced olfactory function, immune suppression, reduced growth, disrupted reproduction, cellular damage
• Lead—Reduced swimming ability, reduced growth, cellular damage, physical/developmental abnormalities
• Nickel—Cellular damage

Trace elements can have synergistic effects when they occur together, meaning that their combined toxicity is more than would be predicted based on the sum of the elements present. This is a possibility when copper is found with mercury, aluminum, iron, or certain pesticides.

Copper in the water in the estuary has been measured at levels high enough (up to 3.8 micrograms per liter) to impair juvenile salmon’s olfaction, or sense of smell.

Sources of Exposure

Trace elements can be introduced to the environment through the atmosphere, soil, groundwater, or surface water as a result of human activities.

In the Columbia River estuary, juvenile salmon are exposed to arsenic, chromium, copper, and lead through river water.

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ⁱ Lower Columbia River Estuary Partnership. 2007. Lower Columbia River and Estuary Ecosystem Monitoring: Water Quality and Salmon Sampling Report.

ⁱⁱ Eisler, R. 1998. Copper Hazards to Fish, Wildlife, and Invertebrates: A Synoptic Review. U.S. Geological Survey, Biological Resources Division, Biological Science Report USGS/BRD/BSR--1998-0002.

ⁱⁱⁱIbid.

^iv Ibid.