Granulometric selectivity in Liza ramado and potential contamination resulting from heavy metal load in feeding areas |
| |
| Authors: | Sílvia Pedro Vera Canastreiro Isabel Caçador Eduarda Pereira Armando C Duarte Pedro Raposo de Almeida |
| |
| Institution: | 1. Institute of Oceanography, Faculty of Sciences of the University of Lisbon, Campo Grande, 1749-016 Lisbon, Portugal;2. University of Évora, Department of Biology, Largo dos Colegiais 2, 7004-516 Évora, Portugal;3. CESAM and Chemistry Department, University of Aveiro, 3810-193 Aveiro, Portugal |
| |
| 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 > Cu ≈ 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 μm 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. |
| |
| Keywords: | Heavy metals Mugilidae Feeding behaviour Grain size Sediment pollution Tagus estuary |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
