algae possess ecological mutability so they can survive in contaminated habitat
(Kalugina-Gutnik 1975). Closely related species may exhibit different accumulation capabilities for trace elements, so there is a need to identify indicators that are
biologically dominant and widespread in the ecosystems. This will allow intraspecific comparison of accumulated metal concentrations over large geographical
areas (Rainbow 1995; Rainbow and Phillips 1993).
HM are among the most studied contaminants in marine ecosystems. Their
effect is through direct poisoning as well as by accumulation and transfer along
the trophic chain, by which they influence the functioning of biosphere (Babich
et al. 1985).
Metal levels in algae reflect local geology or local anthropogenic activities and
the contamination is generally similar to background levels of the sites. Today’s
HM concentrations in marine environment are generally more than ten times higher
than it was in prehistoric times. The levels are consistently higher in surface waters
than in deeper ones along the sea coast during the period spring 1996 to summer
2002. Fe has a great binding capability for alga lipids and is accumulated to the
highest degree in the Black Sea green macrophytes.
The measured Fe concentrations in Bulgarian algae are with one or two orders of
magnitude higher than the other HM (with mean value 650 μg/g). Maximum Fe
values are obtained for C. vagabunda, C. coleothrix and C. gracilis, while in the
other three species Fe content is three times lower. A higher value of Fe is observed
in E. intestinalis from Sinemoretz and Rezovo (autumn 1996 and summer 2000,
respectively). The lowest Fe concentration was measured in U. rigida species from
Ravda (spring 1998) and at Ahtopol (autumn 1996).
If mean Fe values are compared in all green algae depending on the location, a
tendency is obtained of increasing Fe content from north to south. If Fe values are
plotted for each green species vs. location, it is clear that the observed north-south
tendency is mainly due to Enteromorpha species whose values increase southwards. Fe concentration for the other green species is more constant with geographical location (e.g., mean Fe values vs. location for U. rigida are in the range
300 Æ 170 μg/g for the whole Black Sea coast).
The results for Mn vary in narrower interval than Fe (mean value 84 μg/g). Low
Mn content is measured for U. rigida, E. intestinalis and B. plumosa, while the
highest is obtained for C. coleothrix. Mn concentrations in different regions change
in the following order:
Ahtopol < Kaliakra < Shabla < Tuzlata % Ravda < Sinemoretz < Rezovo.
The mean Mn values for Tuzlata, Ravda and Sinemoretz are close and it is
evident that there is no geographic dependence for Mn content. Our data show that
green algae from Kaliakra (north) and Ahtopol (south) sites accumulate Fe and Mn
to the lowest extent while the highest content is measured at Rezovo (south). The
high Fe and Mn biosorption, compared to the other HM, is connected with their
function and major role in the metabolytic processes in marine organisms.
The trace element Cu (like Fe) belongs to the group of biologically important
metal ions. Trace metals should be monitored because they play an important role
18 Radioecology of the Black Sea
321
(Kalugina-Gutnik 1975). Closely related species may exhibit different accumulation capabilities for trace elements, so there is a need to identify indicators that are
biologically dominant and widespread in the ecosystems. This will allow intraspecific comparison of accumulated metal concentrations over large geographical
areas (Rainbow 1995; Rainbow and Phillips 1993).
HM are among the most studied contaminants in marine ecosystems. Their
effect is through direct poisoning as well as by accumulation and transfer along
the trophic chain, by which they influence the functioning of biosphere (Babich
et al. 1985).
Metal levels in algae reflect local geology or local anthropogenic activities and
the contamination is generally similar to background levels of the sites. Today’s
HM concentrations in marine environment are generally more than ten times higher
than it was in prehistoric times. The levels are consistently higher in surface waters
than in deeper ones along the sea coast during the period spring 1996 to summer
2002. Fe has a great binding capability for alga lipids and is accumulated to the
highest degree in the Black Sea green macrophytes.
The measured Fe concentrations in Bulgarian algae are with one or two orders of
magnitude higher than the other HM (with mean value 650 μg/g). Maximum Fe
values are obtained for C. vagabunda, C. coleothrix and C. gracilis, while in the
other three species Fe content is three times lower. A higher value of Fe is observed
in E. intestinalis from Sinemoretz and Rezovo (autumn 1996 and summer 2000,
respectively). The lowest Fe concentration was measured in U. rigida species from
Ravda (spring 1998) and at Ahtopol (autumn 1996).
If mean Fe values are compared in all green algae depending on the location, a
tendency is obtained of increasing Fe content from north to south. If Fe values are
plotted for each green species vs. location, it is clear that the observed north-south
tendency is mainly due to Enteromorpha species whose values increase southwards. Fe concentration for the other green species is more constant with geographical location (e.g., mean Fe values vs. location for U. rigida are in the range
300 Æ 170 μg/g for the whole Black Sea coast).
The results for Mn vary in narrower interval than Fe (mean value 84 μg/g). Low
Mn content is measured for U. rigida, E. intestinalis and B. plumosa, while the
highest is obtained for C. coleothrix. Mn concentrations in different regions change
in the following order:
Ahtopol < Kaliakra < Shabla < Tuzlata % Ravda < Sinemoretz < Rezovo.
The mean Mn values for Tuzlata, Ravda and Sinemoretz are close and it is
evident that there is no geographic dependence for Mn content. Our data show that
green algae from Kaliakra (north) and Ahtopol (south) sites accumulate Fe and Mn
to the lowest extent while the highest content is measured at Rezovo (south). The
high Fe and Mn biosorption, compared to the other HM, is connected with their
function and major role in the metabolytic processes in marine organisms.
The trace element Cu (like Fe) belongs to the group of biologically important
metal ions. Trace metals should be monitored because they play an important role
18 Radioecology of the Black Sea
321