Abstract
In the Upper Columbia River (UCR) between Trail, BC, and Grand Coulee Dam, WA, it has been hypothesized that metals associated with sediments might be contributing to poor recruitment of white sturgeon. Accordingly, the present study employed laboratory flow-through tests to characterize chronic toxicity of UCR sediments to early life stages of white sturgeon (Acipenser transmontanus). Sediments were collected from areas of the UCR known to be sturgeon spawning- and/or nursing-grounds and contained a range of concentrations of metals of primary interest, including copper (Cu), cadmium (Cd), lead (Pb), and zinc (Zn). Early life stage white sturgeon were exposed for 60 days and survival and growth were related to concentrations of metals in bulk sediment, pore water, overlying water, and water at the sediment-water interface. Based on probable effect concentrations (PECs) and excess simultaneously extracted metals (SEMX), site sediments in the present study had the potential to elicit adverse effects to sediment-dwelling organisms. In addition, the Biotic Ligand Model (BLM) was used to allow for more explicit consideration of bioavailability of metals to white sturgeon. BLM predictions indicated that concentrations of Cu in pore water slightly exceeded the threshold for effects (up to a factor of 2.2) for two of the five site sediments, while concentrations of metals in overlying water and at the sediment-water interface were below the threshold for effects. No effects were observed, however, in survival or growth of white sturgeon exposed to site sediments that were relatable to concentrations of metals. Of the methods used to characterize potential effects due to exposure to metals associated with sediments, BLM predictions corresponded best with the observed results.
Highlights
Populations of sturgeon are threatened throughout the world
There are several significant limitations to determining toxicity of metals in sediments and to date, there is no single, definitive method for deriving sediment quality guidelines (SQGs) or assessing risks posed by metals associated with sediments that is without limitations [39]
Sediments used in the present study covered a range of concentrations of targeted chemicals of potential concern (COPC) that were representative and consistent of the range of concentrations observed in site sediments from the Upper Columbia River (UCR), and captured the upper concentration range of previously reported data
Summary
Populations of sturgeon are threatened throughout the world Factors such as age to reproductive maturity make sturgeons susceptible to alterations in the environment and their benthic lifestyle might result in exposure to contaminants associated with sediments of concern. In some North American rivers it has been hypothesized that metals associated with sediments might be contributing to poor recruitment of white sturgeon (Acipenser transmontanus; [6,7,8]). One population of particular concern that has been experiencing poor annual recruitment for over forty years resides in the Upper Columbia River (UCR), between Grand Coulee Dam in the USA and Hugh L. Specific reasons for the observed decreases in the number of sturgeon are not fully understood, pollution has been hypothesized as one potential contributor to recruitment failure of white sturgeon in the UCR [8]
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