Marine Mammals in a Changing World - Marine Ecology in a Changing World - page 241

compounds in tissues. When source papers expressed concentrations on a
fresh weight basis, we calculated the lipid-based concentrations by dividing
them by sample lipid content (Aguilar 1986). If this latter value was not
available, the concentrations in fresh weight basis were divided by 0.7, a
fi gure that was considered to be a representative means of lipid richness for
blubber (Aguilar et al. 2002). The mean, maximum and minimum values
were directly extracted from the source papers or calculated from the raw
data when available.
During the 1970s and 1980s, research concentrated in Western Europe
and Northern America, clearly refl ected the technical strength of researchers
from these regions. Since the mid 1980s however, the scientifi c production on
the subject in Asia, particularly Japan, and in South America has increased.
Nevertheless, to date, research levels in Australia, the Indopacifi c region
and Africa still remain minimal (Aguilar and Borrell 1996, Aguilar et al.
2002; Table 2).
Not surprisingly, a previous review of the geographic patterns of OCs
pollution in marine mammals showed that the Mediterranean Sea and the
waters of California were the marine environments with the highest Levels
of PCBs and DDTs worldwide (Aguilar et al. 2002, Aguilar and Borrell 2004,
Storelli and Marcotrigiano 2004; Table 2). The highest average level of both
DDTs and PCBs (400 and 1204 µg/g lw) was recorded in fi ve males Tursiops
truncatus of Mediterranean Sea in 1992 (Corsolini et al. 1995). Nevertheless,
a decreasing trend was confi rmed by FD values. DDTs and PCBS for
1978 to 2002 decreased by factors of 23.7 and 6.1 for Tursiops truncatus of
Mediterranean Sea (Borrell and Aguilar 2007). This negative trend was also
recorded for T. truncatus from 1980 to 1990 in the Indian Ocean (FD PBCs
= 12, DDTs = 2, Table 2). Similar trend was recorded for Phocoena phocoena ;
DDTs and PCBs decreased by factors of 3.8 and 1.4 (for 1989 to 2000 and
1989 to 2010 respectively) in North and Belgian Seas (Fig. 2; Table 2). While
the same negative trend is repeated (FD 1994-2004 PCBs = 1.4, DDTs = 2.2) for
Pontoporia blainvillei from Rio Grande do Sul, in southern Brazil. The trend
was positive particularly for PCBs (FD 1991-2007 = 0.1) in Sao Paulo and Parana
to the north of the country. The concentrations found between 2001 and
2007 were the highest recorded for the last millennium in the Southwestern
Atlantic Ocean (13 µg/g lw; Table 2). Finally, PCBs showed an increase in
their levels during 1980s in Gulf of México (FD 1983-1987 = 1.7) and after the
early 90's PCBs levels gradually declined until late 90's (FD 1991-1996 = 2.7),
from 1996 to 2001 the levels increased in a factor of 0.2. Johnson-Restrepo
and col. (2005) reported the highest concentration of PCBs ever recorded
for the Gulf of Mexico (240 µg/g lw; Table 2). DDTs also showed a decrease
in a factor of 2.3 from 1987 to 1991 (Fig. 2; Table 2).