Cells were counted in a Sedgwick-Rafter chamber and 

 their concentration was adjusted to 100 cells/ml for use during 

 the toxicity test. 



To be certain that the dinollagellate culture emits the 

 maximum quantity of light, it is necessary that the culture be 

 stirred vigorously. An acrylic rod was fitted into the chuck of 

 a variable speed electric motor drive set at -100 rpm. During 

 the test, the rod was inserted approximately two-thirds of the 

 way into the vial containing the test medium and P. lunula cells 

 and stirred for 2 min to ensure that the light producing ability 

 of the dinoflagellate was exhausted. 



A solid state photometer ( Stiffey et al. , 1 985 ; Stiffey et cil. , 

 1987) measured biolummescence and a multirange stripchart 

 recorder with a chart speed of 3 cm/min was connected to the 

 photometer that was adjusted so that the recorder registered the 

 cumulative light fluxes as a function of time (Fig. 3). 



PHOTOTUBE 



DDDII 



AMPLIFIIiR 



RliKlRDPK 



Fig. 3. Equipment used for the measurement of luminescence intensity. 



Station 



3 



7 



9 



13 



18 



22 



35 



45 



47 



50 



55 



59 



61 



64 



67 



69 



75 



96 



109 



110 



TABLE 2 



Stations Where Sediments Were 



Tested And Results of 



Toxicity Tests. 



Artcmia 



Pxrocx.sris 



The percentage of bioluminescent quenching was 

 calculated with the following equation: 



% quenching : 



C-E 



X 100 



where C = displacement of the reorder pen ( in mm) during the 

 stirring of the control culture, and E = the displacement of the 

 pen during stirring of the test elutriate (Stiffey, 1990). 



Depending on the degree of toxicity of the test medium, 

 bioluminescence may be totally suppressed, or a degree of light 

 diminution relative to seawater controls may be noted. If any 

 decrease in bioluminescence was observed, an LC^,, was 

 calculated (Peltier & Weber, 1985). 



Results and Discussion 



For the stations examined, none of the sediments appear to 

 be acutely toxic to A. salina and P. luuuUi (Table 2). This 

 agrees with the levels of contamination reported from this 

 region detemiined by chemical analysis (Rice <»;«/.. Subchapter 

 8.1.3, this volume; Krynitsky et al.. Subchapter 8.3.2, this 

 volume). Since toxicity was not observed, LC^„ values were 

 not calculated. This illustrates the rapidity and cost-effectiveness 

 of initial screening for toxicity. In a hierarchical approach to 

 ecotoxicological assessment, a positive indication of toxicity 

 would have triggered a series of assessment procedures where 

 definitive toxicity tests, field experiments, and other 

 investigations could be performed. A negative response allows 

 resources to be redirected to areas of greater concern. 



These two toxicity tests showed great potential for use on 

 research vessels and to generate timely information that could 

 be pursued while the vessel is still on-station. During a 

 catastrophe such as an oil spill, a rapid assessment of toxic 

 impact can direct prevention and clean-up procedures, which 

 can maximize the effort in protecting valuable fish and wildlife 

 resources. 



The organisms are easy to culture and maintain and require 

 very little in terms of space and equipment. End-points such as 

 mortality or diminution of bioluminescence are easy to measure 

 and provide clearly defined criteria for assessing the quality of 

 the sediment. 



Several drawbacks in using these tests do exist and reflect 

 not so much the limitations of these particular tests but the 

 symptomatic problems confronting toxicity testing in general 

 (Kimball & Levin, 1985). While the suspended particular 

 phase testing is a proper approach for use with pelagic organisms 

 such as Artentia and Pyrocystis, it is not a direct measure of 

 sediment toxicity. It would have been desirable to use a 

 sediment-dwelling organism. While much research is being 

 conducted in the area of sediment toxicity testing, it as not as 

 well developed as water-phase testing (Levin et al. , 1 984; Long 

 & Chapman, 1985). The lack of cultured benthic species is a 

 major limitation. With a wide spectrum of sediment types 

 found in the marine environment and with each benthic species 

 having its own tolerance for sediment substrate, the definitive 

 marine sediment test that is rapid and cost-effect is still to be 

 developed. A promising approach may be the use of artificially 



375 



