Trace metals (Cu, Zn, Cd and Pb) in juvenile fish from estuarine nurseries along the Portuguese coast

Abstract

SUMMARY: Organic and inorganic pollution can impact organisms directly and affect condition, growth and survival of juvenile fish which use estuaries as nurseries, and thereby affect marine adult populations quantitatively and qualitatively. Trace element contamination (Cu, Zn, Cd, Pb) in juveniles of commercial fish Solea solea, Solea senegalensis, Platichthys flesus, Diplodus vulgaris and Dicentrarchus labrax collected in putative nurseries of the main Portuguese estuaries (with diverse intensities and sources of anthropogenic pressures) was determined via atomic absorption spectrometry. Contamination was significantly different among species. Similar levels of contamination were found among estuaries, except for D. vulgaris. Cu and Zn concentrations ranged from 1.0 to 2.1 and 14 to 59 µg g -1 muscle dry weight respectively; while Cd and Pb concentrations were very low. The results indicate that juvenile migration to off-shore habitats is associated with low export of contamination, and no particular estuary increases the potential contamination of adult stocks. This knowledge is of the utmost importance in view of the ecological and economical value of these species and their use of estuarine areas as nurseries.Keywords: juveniles, nursery grounds, populations, anthropogenic effects, heavy metals. RESUMEN: Metales traza (Cu, Zn, Cd y Pb) en peces juveniles de las guarderías estuáricas a lo largo de la costa portuguesa. -La contaminación orgánica e inorgánica puede afectar a los organismos, a saber al estado fisiológico, crecimiento y supervivencia de los peces juveniles los cuales utilizan los estuarios como guarderías; afectando de forma cuantitativa y cualitativa a la poblaciones marinas adultas. La contaminación de elementos traza (Cu, Zn, Cd, Pb) en las formas juveniles de los peces comerciales Solea solea, Solea senegalensis, Platichthys flesus, Diplodus vulgaris y Dicentrarchus labrax recolectados en guarderías putativas de los principales estuarios portugueses (con diversos tipos e intensidades de presiones antropogénicas) fueron determinados por espectrometría de absorción atómica. La contaminación era significativamente diferente entre especies. Sobre todo se encontraron niveles similares de contaminación entre estuarios, excepto para D. vulgaris. Las concentraciones de Cu y Zn oscilaban desde 1.0 a 2.1 y desde 14 a 59 µg g -1 peso seco muscular, respectivamente, mientras que las concentraciones de Cd y Pb eran muy bajas. Los resultados indican que la migración de los juveniles a mar abierto está asociada a la baja exportación de la contaminación y que los estuarios no amplifican particularmente el potencial de contaminación de los adultos. En vista del valor ecológico y económico de estas especies y del uso de las zonas estuáricas como guarderías, este conocimiento es de vital importancia.

Metal concentrations, growth and condition indices in European juvenile flounder (Platichthys flesus) relative to sediment contamination levels in four Eastern English Channel estuaries

“…For a given size, lower levels of metals were observed in the muscle tissues compared to other organs with distinct physiological functions and in particular the liver is often recommended for monitoring the metal contamination in aquatic environment. 49,51,52 The study of Vasconcelos et al 19 showed no significant differences in metal accumulation in flounder muscles among estuaries. The authors suggested that the limited time spent by the juveniles in the estuaries, estimated to be about three months, could explain both their relatively low levels of contamination in muscles and the lack of difference in metal accumulation among estuaries.…”

“…A recent study 19 has reported metal concentrations measured in the muscle of five fish species with an average length of 83.5 AE 7.0 mm for juvenile flounder. For the investigated metals, juvenile flounder from three Portuguese estuaries showed detectable levels for the two analysed essential metals (Cu and Zn) in muscle.…”

“…14 To the best of our knowledge, until now, only one study has reported on metal concentrations from such an early life history stage of flounder in estuarine nursery areas, namely along the Portuguese coast. 19 2 Materials and methods 2.1 Sampling sites and collection 0-group juvenile flounder (less than one year old) were collected during the spring period (late May-early June 2008) from four estuarine nursery grounds located along the French coast of the Eastern English Channel (Fig. 1).…”

Growth, condition and metal concentration in juveniles of two Diplodus species in ports

“…Our results therefore provide valuable information about muscle contamination in these two species, especially for Al and Ti, for which very few data exist in the literature. To our knowledge, only one study so far has measured metal concentrations in the muscle of Diplodus juveniles in the wild, in D. vulgaris from six natural estuarine nursery sites spread along the Portuguese coast, and considered as slightly to moderately polluted (Vasconcelos et al, 2011). Muscle contamination levels for Cu and Zn in this work (of 2.1 mg.kg -1 dm and 28 mg.kg -1 dm on average, respectively) were close to those found for D. vulgaris in our study (Table 3), with the exception of the Cu concentrations observed in STM (2.0-8.9 mg.kg -1 dm).…”

“…Yet, many coastal habitats under high anthropogenic influence, like most estuaries and coastal lagoons, have been shown to sustain important densities of juvenile fish with high growth rates (Beck et al, 2001;Franco et al, 2006;Gibson, 1994) and are, as such, listed as nursery habitats for many species. As recipients of industrial and domestic wastes, these systems are subjected to moderate to high pollution (Amara et al, 2007;Courrat et al, 2009;Vasconcelos et al, 2011), which does not seem to alter their nursery function.…”