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|Title: ||Granulometric selectivity in Liza ramado and potential contamination resulting from heavy metal load in feeding areas|
|Authors: ||Pedro, Sílvia|
Duarte, Armando C.
Almeida, Pedro R.
|Keywords: ||Heavy metals|
|Issue Date: ||22-Aug-2008|
|Abstract: ||The stomach contents of thin-lipped grey mullets Liza ramado were analysed in terms of granulometric
composition and compared to the sediment of potential feeding areas in the Tagus estuary. Total organic
matter (TOM) content and heavy metal content were determined in the surface sediment of three areas
and eight trace elements were quantified: Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn. The three sampled areas did
not differ in TOM; and the heavy metal content was below Effects Range-Low level for most elements. The
mean observed concentrations were present in the following sequence: Zn > Pb > Cr > Cuz
Ni> Co > Cd > Hg. Stomach contents granulometric composition provided information about the feeding
selectivity of the mullets. Sediment fractions with particle size between 20 and 50 mm are preferred,
independently of the fishes’ length. Smaller standard length (SL) fishes have a higher positive selection of
fine grained sediments than those with a larger SL. Finer fractions usually have higher concentration of
heavy metals, which makes younger specimens of the thin-lipped grey mullet potentially more exposed
to heavy metal load in the estuary. Metal concentration was not independent from the sampling point,
presenting higher values near the margins and the estuary tidal drainage system. This means that during
the first period of each tidal cycle, the mullets will feed first on the most contaminated areas, as
a consequence of their movement following the rising tide to feed on previously exposed areas.|
|Appears in Collections:||BIO - Publicações - Artigos em Revistas Internacionais Com Arbitragem Científica|
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