Workplans on Study Design - Bed Sediment and Fish Tissue

Science Center Objects

Bed-sediment and fish-tissue studies are used in NAWQA to assess the presence and distribution of trace elements and hydrophobic organic contaminants that are less likely to be found in surface-water samples.

Contaminants in fish tissue

National target taxa for NAWQA are white sucker (Catastomus commersoni) and common carp (Cyprinus carpio), because of their benthic feeding habits and their nearly ubiquitous distribution throughout the Nation. The Delaware River Basin NAWQA will target white suckers as the priority taxon because white suckers are present in both large rivers and small streams throughout much of the Delaware River Basin, whereas carp are not likely to be present at forested indicator sites and other small streams that are not highly disturbed. In addition, white suckers were the priority target taxon for most of neighboring NAWQA study units in the northeast and they were also collected by some of the state agencies at some sites.

Common carp will be the Delaware NAWQA's second priority target taxon, to be collected at sites where white suckers are not encountered in sufficient numbers. Both white suckers and common carp will be collected at 1 or more sites where both are encountered to provide overlap of National target taxa, which will facilitate interspecific comparisons within the study unit as well as regionally and nationally.

Each tissue sample for organics analysis will consist of composits of 6-10 similarly-sized adult whole fish. Samples for mercury and trace elements analysis are collected from livers. In both cases either the whole fish or the livers are composited and homogenized for analysis. For quality assurance purposes two or three samples of the same species will be collected at 1 or more sites to provide replication at approximately 10% of sites. All specimens will be collected by electrofishing, and then split among 2 to 3 composites, to provide "split" (vs. "sequential") QC samples.

Our liaison committee has expressed strong preferences for tissue contaminant data in game species, to address human-health concerns. State agencies typically collect standard (skin-on) fillets from game species, and process the edible portion for both organics and metals concentrations. We will collect edible portions of game species, either Bass or Trout, at some NAWQA tissue sites for this comparison.

Contaminants in Bed Sediments

Bed sediment samples will be collected at all fixed sites, all fish tissue sites, and an additional 10 to 20 synoptic sites. This sampling would tie in with ourĀ surface water synoptic work. A series of similarly sized basins across the study unit with differing percentages of agricultural, urban, and mixed land uses would be sampled. Replicate sampling will be conducted at 10 percent of our sites for quality assurance purposes. Sequential replication will be conducted in order to assess variability associated with sample collection, as well as sample processing.

Schedule for Bed Sediment and Tissue work in 1998 - 2001

Work started in 1998 on the Occurrence Survey of Bed Sediment and Fish Tissue. All fixed sites have been sampled. 10 additional fish tissue sites have been sampled and 20 additional bed sediment sites have been sampled through the Summer of 1999. (BS&T sites) Additional sampling may be conducted in the Summer of 2000.