PARENT SESSION

PW08 Aquatic Ecotoxicology II
Exhibit Hall
8:00 AM - Wednesday

(PW110) Validation of Alternative Procedure for Conducting the Giant Kelp (Macrocystis pyrifera) 48-Hour Germination and Growth Bioassay.

Wiborg, L¹, Bailey, H², Gutoff, D¹, O'Donohue, D¹, Baugh, O¹, Kelly, M¹, ¹ City of San Diego Metropolitan Wastewater Dept., Environmental Monitoring & Technical Services Div., Marine Biology Laboratory, San Diego, CA, USA² AMEC Earth & Environmental, San Diego, CA, USA

ABSTRACT- The giant kelp 48-hour germination and growth test has been widely utilized in NPDES compliance testing programs. An informal survey of several laboratories showed the method to be readily adaptable to smaller test chamber size and test solution volume. In 2003-2004, the City of San Diego conducted seven sets of sided-by-side copper chloride reference toxicant tests to compare the standard and modified methods. Average control results for the germination endpoint were 96.0 and 93.3 percent for the standard and modified methods, respectively; and the corresponding coefficients of variation were 1.8 and 4.6%. The control performance for the growth endpoint averaged 12.4 and 12.5 m for the standard and modified methods, respectively, and the corresponding coefficients of variation were 15.6 and 9.3%. With the exception of the growth endpoints in one of the standard method tests, all tests met the test acceptability criterion of achieving a no-observable effect concentration (NOEC) of <35 g/L copper. All tests met the test acceptability criterion of achieving a percent minimum significant difference (MSDp) necessary to detect a difference from the controls of <20%. Reference toxicant parameters were generally similar between the two methods except for the growth endpoint EC25 values.

Key words: Giant kelp (Macrocystis pyrifera)