Establishing Baselines and 

 Reference Areas 



In addition to the high-level indicators discussed below, certain 

 low-level indicators — tissue residues and fish distribution and 

 abundance, for example — should also be considered for use in 

 monitoring studies. 



Macrophage triad. The macrophage triad is a useful early warning 

 of general stress. Macrophage cells exhibit three behaviors, or 

 responses, that have demonstrated a direct relationship to the 

 presence of toxics. 



Enzymes (mixed function oxidases, metallothionein). Certain 

 enzymes or proteins may be produced by an animal as a result of 

 exposure to various classes of pollutants. Immunological methods 

 measure the presence and amounts of the enzymes or proteins 

 produced. 



Hematology. Routine clinical tests of blood components can pro- 

 vide information about the physiological condition of the animal. 

 They can also detect general stress. 



Cytogenetics. Cytogenetics examines the relationship between 

 changes in the chromosomal structure and pathological conditions. 

 These changes can be linked to exposure to specific pollutants. 



Histopathology. Finfish disease can be exhibited through struc- 

 tural change in tissues or organs during the course of an animal's 

 exposure to pollutants. Tissue and organ abnormalities are ob- 

 served using standard light microscopy techniques. Although 

 these studies are more expensive, they can detect specific lesions 

 that develop shortly after pollutant exposure, and long before gross 

 abnormalities develop. 



Egg and larval development and viability. Eggs and larvae are 

 sensitive stages in the life cycle of fish. Problems with egg or larval 

 development, such as death or deformity, indicate an ecological 

 effect that may be due to toxic contamination. 



Estuary program managers should establish baseline and/or con- 

 trol data for the species and indicator methods under consideration. 

 Where historical data are inadequate, a reference area should be 

 established. NOAA's Status and Trends Program has already set 

 up reference areas in or near most of the estuaries in the National 

 Estuary Program. Reference areas, which should be repre- 

 sentative of the entire estuary under study, should be relatively free 

 from toxic effects. If such an area cannot be found, estuary 

 program managers should look for nearby areas with comparable 

 hydrographic and faunal conditions. 



C6 



