MacGREGOR: AMOUNT AND PROPORTIONS OF DDT 



California Current is usually farther offshore 

 than at the surface (Wyllie, 1966). In April and 

 May this current moves inshore eliminating the 

 countercurrent at the surface and sometimes at 

 200 m. When the California Current is offshore, 

 the surface countercurrent develops; when it 

 moves onshore, the surface countercurrent is ab- 

 sent although the southern California eddy usu- 

 ally persists. 



The currents, and consequently the distribution 

 of the sewer discharge, are influenced locally by 

 such factors as the configuration of the coast, the 

 presence of islands, the topography of the ocean 

 floor, and the short range effects of winds and 

 tides. 



The total DDT data for the myctophids were 

 divided into four time periods, and the average 

 DDT value determined for all specimens taken at 

 each station, or combined stations if they were 

 very close together, for each time period (Figures 

 5-8). The total DDT content of the fish tended to be 

 high near the sewer outlet and decreased away 

 from the outlet. Total DDT values increased with 

 the passage of time. 



Total DDT for the purpose of this discussion 

 consists of DDT, DDE, and DDD. Although total 

 DDT content in the myctophids increased with 

 time, this did not hold true for each of the three 

 constituents. DDT increased for a few years until 



metabolism and dispersion equalled input and 

 then leveled off. DDD acted in a similar manner 

 but at a lower level. Most of the increase in total 

 DDT after the first few years was caused by the 

 increase in the persistent metabolite, DDE. The 





ColCOFI STATION NUMBERS 



Figure 6. — Average total DDT at CalCOFI stations off southern 

 California for the 4 yr 1953-56. 



s 



3 



97.80 .75 70 .65 .60 ,55 50 .45 40 .35 50 



CalCOFI STATION NUMBERS 



CalCOFI STATION NUMBERS 



Figure 5. — Average total DDT at CalCOFI stations off southern 

 California for the 3 yr 1950-52. 



Figure 7.— Average total DDT at CalCOFI stations off southern 

 California for the 4 yr 1957-60. 



283 



