DISTRIBUTION OF METALS AND ZOOPLANKTON IN A HEAVILY INDUSTRIALIZED ESTUARY (BAHIA BLANCA ESTUARY, ARGENTINA). VALUABLES TOOLS IN THE ASSESSMENT OF ECOSYSTEMS CONDITIONS

FERNANDEZ SEVERINI, M.; BOTTÉ, S.E.; HOFFMEYER, M.; MARCOVECCHIO, J.E.

Figueira da Foz

Simposio; ECSA 47 Symposium; 2010

IMAR-Institute of Marine Research (U.Coimbra) and CO-Centre of Oceanography (U.Lisbon)

The present work constitutes one of the first studies of metals concentrations in the zooplankton from a heavily industrialized estuary of Argentina, the Bahía Blanca estuary. In this study we considered Cd, Cu and Pb concentrations in the zooplankton (macro and mesozooplankton), in the dissolved phase and in the suspended particulate matter. The major physicochemical variables and zooplankton composition and abundance were also taken into account. Thus, the aim of the present work was to analyze the spatial and temporal distribution of heavy metals in the different fractions, and the possible relationships among them due to their importance in the biogeochemical cycles. Moreover, zooplankton and metals analyses are a valuable tool in the assessment of the ecosystems conditions. Samplings were carried out from March 2005 to April 2006, every two months, at stations located near chemical and petrochemical industries and stations far from these points. The physicochemical variables agreed with historical values for the estuary, and did not present any evidence of abnormality. In addition, zooplankton composition and abundance presented the typical seasonal behavior found in the estuary. Dissolved Cd, Cu and Pb presented a mean concentration of 0.19 ±0.005, 1.67 ±0.11 and 2.35 ±0.48 µg L-1 respectively, while particulate: 1.88 ±0.75, 11.20 ±2.08 and 16.92 ±3.01 µg g-1 d.w. In the mesozooplankton the concentrations of Cd, Cu and Pb were: 4.10±1.35, 32.48±5.14 and 13.32±3.49 µg g-1 d.w. In the macrozooplankton: 1.09±0.26, 22.42±5.23 and 7±1.95 µg g-1 d.w. Metals´ levels in all the fractions, fluctuated throughout the study time and were relatively high in the dissolved and particulate phases especially for Cu and Pb. Moreover, zooplankton accumulated important concentrations of the three metals. The sources of them are probably the discharges of the industries and domestic sewages located near the estuary. This work contributed to the assessment of the ecosystem condition of the estuary and nowadays, it is been carrying out a multi-disciplinary program which considers metals concentrations in several matrixes as well as the physical forces that drive metals distribution in the Bahía Blanca estuary