Solid Phase Sediment Toxicity Test with the Amphipod Rhepoxynius abronius 



This toxicity test has been tested and evaluated extensively (Swartz et al, 1985; Mearns 

 et al, 1986; DeVVitt et al, 1988) and used in many environmental surveys (Williams et al, 

 1986; Swartz et al, 1982; Swartz et al, 1986), primarily in the Pacific Northwest. 



Animal collections. The burrowing infaunal amphipods, Rhepoxynius abronius, were collected 

 subtidally from West Beach, a relatively remote site on Whidbey Island (Washington 

 State), using a bottom trawl. 



Test Procedures. Following their arrival in the laboratory, amphipods were kept in 

 holding containers filled with fresh seawater (28 parts per thousand (ppt) salinity) and 

 maintained at 15 ± 1°C under continuous light until used in testing. Cultures were aerated but 

 not fed during acclimation and were held for 5 days prior to testing. Amphipods were hand 

 sorted from sediments and identifications were confirmed using a Wild M5 dissecting 

 microscope. Individuals that were damaged, dead, or unable to rebury in acclimation 

 sediments were discarded. 



Acute lethality of sediments was measured in a 10-day exposure to test sediments 

 following the methodology of Swartz et al (1985) as amended by Chapman and Becker (1986). 

 A 2-cm layer of test sediment was placed in 1-L glass jars and covered with 800 mL of clean 

 seawater (28 ppt salinity). The interstitial salinities of all test containers were measured 

 after seawater addition and found to be 27 + 2 ppt. Each beaker was seeded randomly and 

 without knowledge of station identification with 20 amphipods, covered, and aerated. Six 

 replicates were run per station. Five beakers were used to determine toxicity, while a sixth 

 beaker was used to measure water chemistry daily (pH, dissolved oxygen, salinity, 

 temperature). Containers were checked daily to establish trends in mortality and sediment 

 avoidance, and also to gently sink any amphipods which had emerged from the sediment 

 overnight and become trapped by surface tension at the air/water interface. A control 

 sediment from the amphipod collection site was tested concurrently with the sediments from 

 the five sites. This site had been previously documented to be nontoxic to amphipods (Terra 

 Tech, 1985). 



After 10 days, sediments were sieved (0.5-mm screen), and live and dead amphipods were 

 removed and counted. Amphipods were considered dead when there was no response to 

 physical stimulation and microscopic examination revealed no evidence of pleopod or other 

 movement. Missing amphipods were assumed to have died and decomposed prior to the 

 termination of the bioassay (Swartz et al, 1982; 1985). The amphipod avoidance end-point 

 was determined from daily counts of amphipods that had emerged from the sediments. At 

 the end of the 10-d exposure, live amphipods were transferred to a fingerbowl containing a 2- 

 cm deep layer of control sediment and clean bioassay water. The number of individuals that 

 had reburied within 1 hour was recorded to determine the percent reburial end-point. All but 

 sample numbers 8 and 9 were tested in the first batch. 



Parallel reference toxicant bioassays (96-h LC50 tests in clean water without sediment) 

 were conducted using sodium pentachlorophenate (NaPCP). A 100 parts per million (ppm) 

 stock solution of NaPCP was prepared in a 0.04 mole (mol) solution of sodium hydroxide 

 using anhydrous grade pentachlorophenol (Sigma Chemicals), following procedures described 

 in Niimi and McFadden (1982). Bioassay concentrations were prepared in duplicate by 

 volumetric dilution of the NaPCP stock solution with filtered seawater. The concentrations 

 of NaPCP tested were: 1,000, 750, 560, 320, 180, and 100 ug/L. 



Solid Phase Sediment Toxicity Test with the Amphipod Ampelisca abdita 



This toxcicity test has been developed in New England by Scott and Redmond (in press) 

 and has thus far been used on a limited basis in environmental surveys (Gentile et al, 1987). 



