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CHRONIC TOXICITY OF SUBLETHAL CADMIUM EXPOSURE IN
MARINE BIOTA FROM BRACKISH ENVIRONMENTS


Pia Elena Mihnea, G. Munteanu and Elena Ghitescu
Romanian Marine Research Institute Constanta

Abstract
Chronic effects of cadmium (Cl2Cd 0.1 and 0.5 ?g??) on the alga
Chloromonas paradoxa var. paradoxa KORSCHIKOFF, were assayed as well
as potential transfer in food webbs from algae to the consumer 
Mytilus galloprovincialis LAM. The response of alga included: (1)
stimulated division rate for three days followed by decrease to 50%
(of the control rate) and 0.5 ?g Cd ??? exposure; (2) dry weight 
increased in 0.1 and 0.5 ?g ?? exposure, mainly in the third and
fourtheenth days of exposure; (3) the pigments levels were reduced 
(% from the control value): for neoxanthin 76.99-81.83, violaxanthin
67.0-89.20, lutein 71.08-81.49, chlorophyll a 80.57-88.26, chlorophyll
b 76.21-86.44, and carotens 68.93-98.54; (4) the total amino acids
exceeded the control value by 71.33 (0.1 ?g Cd ???) and 46.51%
(0.5 ?g Cd ???), with cystine + methionine, alanine, phenylalanine,
valine, hystidine, glutamic acid and lysine being particularly
affected; (5) Cd uptake modified the influx of some other divalent
ions (Zn, Cu and Ca): zinc (1,377.61%) and copper (2,872.22%) were
accumulated at concentrations greater than control values; calcium
concentrations were concomitantly reduced (24-29%). Chronic effects
of cadmium on mussels contaminated by feeding: (1) Cd was absorbed
in mussels soft tissues (19.4-40.3% over the control) during chronic
exposure; (2) the absorbed cadmium induced a decrease in zinc
content (0.72-31.20% versus the control), and an increase of Cu
absorption (56.98%) in the case of 4.5-7.5 cm height clase mussels.