Selenium concentrations and stable isotopic compositions of carbon and nitrogen in the benthic clam Corbula amurensis from northern San Francisco Bay, California: May 1995–February 2010

Abstract

The clam-based food webs of San Francisco Bay, California efficiently bioaccumlate selenium and thus provide pathways for exposure to predators important to the estuary. This study documents changes in monthly selenium concentrations for the clam Corbula amurensis, a keystone species of the estuary, at five locations in northern San Francisco Bay from 1995 through 2010. Samples were collected from designated U.S. Geological Survey stations and prepared and analyzed by U.S. Geological Survey methods. Stable isotopes of carbon and nitrogen in soft tissues of clams also were measured as an indicator of sources of selenium for the clams. These monitoring data indicate that clam selenium concentrations ranged from a low of 2 to a high of 22 micrograms per gram dry weight with strong spatial and seasonal variation over the period of study.

Estimation of Contaminant Loads from the Sacramento‐San Joaquin River Delta to San Francisco Bay

“…San Francisco Bay is listed under Section 303(d) of the Clean Water Act as impaired for Se because concentrations may exceed levels that cause reproductive impairment in birds and fish (Water Board 2011). Bioaccumulation poses a threat to many estuarine organisms, and high Se concentrations for Suisun and Northern San Francisco Bay have been reported in bivalve tissue (Kleckner et al, 2010) and white sturgeon (Stewart et al, 2004). The concentrations measured in water in the present study were far below the chronic guideline for freshwater (4-day average) of 5 lg/L for San Francisco Bay and the Delta and below a water quality objective of 1 lg/L that US Fish and Wildlife Services support as a more protective guideline for aquatic life.…”

Brackish water foraging: isotopic landscapes and dietary reconstruction in Suisun Marsh, Central California

“…3 plots data from modern plant and animal samples amalgamated from a wide range of studies in and around Suisun Marsh, including San Francisco Bay and the California Delta (data assembled from Bartelink, 2006;Canuel et al, 1995;Cloern et al, 2002;Goldberg, 1993;Greenfield et al, 2002;Grenier et al, 2002;Howard et al, 2005;Howe and Simenstad, 2011;Kleckner et al, 2010; Newsome et al, 2009Newsome et al, , 2012Rast, 1989;Sarakinos et al, 2002;Sydeman et al, 1997). Given large inputs of fertilizer and sewage into modern waterways, and extreme changes to the local ecology, especially the effects of invasive species, it is difficult to estimate how applicable modern data are to reconstructing ancient foodwebs in Central California (Wankel et al, 2006).…”

Influence of estuarine processes on spatiotemporal variation in bioavailable selenium

“…2, Fig. S1 in Supplement A) (Kleckner et al 2010). Mean monthly Se concentrations at Stns 4.1 and 8.1 were roughly 2 to 20% greater than the 17 yr annual mean in September through December (n = 4 mo).…”

“…A total of 10% of the clam tissue samples in a run were analyzed in duplicate, and digestion blanks were processed to ensure the purity of the acids and other reagents. Detailed QA/QC results are provided in Table 2 in Kleckner et al (2010). Se concentrations are expressed on a dry weight basis (µg g −1 ).…”

“…Instrument precision was 0.1 ‰ for carbon and 0.3 ‰ for nitrogen based on replicate analyses of standard reference materials. Detailed QA/QC results are provided in Kleckner et al (2010).…”