Análisis espacial de la concentración de metales en el camarón gris Crangon crangon (Linnaeus, 1758) en el Mar del Norte meridional

Spatial distributions of Cu, Pb, Cd, Ni and Zn concentrations in brown shrimps Crangon crangon (Linnaeus, 1758) collected on a cruise of FRV Walther Herwig III to the southern North Sea in January 2004, were investigated on a scale of 18 x 18 km to evaluate the range of spatial autocorrelations for the different variables under study. Semivariogram models obtained by geostatistical procedures indicated a distinct increase in variability for most variables with sampling distance. Only if samples are taken at distances above the estimated values for the practical range of the semivariogram can stochastic independence of the data be assumed. These are 6.6 km for Cd, 3.0 km for Ni and 5.2 km for Pb. Contour plots revealed a clear coincidence of high values for Cd, Ni and Pb with low shrimp mean body wet weight. Nevertheless, spatial autocorrelations were rather weak, since classical and geostatistical population estimates for the means and the 95% confidence intervals were in good agreement. The low detected concentrations of Pb in C. crangon were in good agreement with reported data for decapod crustaceans from other regions. For Zn reported values were distinctly below our 95% confidence intervals, while for Cu they were slightly above and for Cd distinctly above concentrations in C. crangon from this study. For Ni no comparative values exist. We conclude that with this integrated biomonitoring approach metal concentrations could be assessed more precisely and relations between biotic and abiotic variables could be evaluated.Se analiza la distribución espacial de las concentraciones de Cu, Pb, Cd, Ni y Zn en el camarón gris Crangon crangon (Linnaeus, 1758) en muestras recolectadas durante una campaña a bordo del BO “Walther Herwig II” en el Mar del Norte meridional en Enero de 2004, en un área de 18 x 18 km. Se investiga el alcance de las funciones de autocorrelación espacial de las distintas variables estudiadas. El análisis de los modelos de semivariograma obtenidos mediante técnicas geostadísticas indica un aumento de la variabilidad para la mayoría de las variables con la distancia. Sólo cuando se toman las muestras a distancias superiores al alcance práctico del semivariograma se puede asumir independencia estocástica entre los datos. Los alcances calculados son 6.6 km para Cd, 3.0 km para Ni y 5.2 km para Pb. Los mapas de isodensidad muestran una clara coincidencia de altos valores de Cd, Ni y Pb con valores bajos de peso medio húmedo de camarón. Sin embargo, las autocorrelaciones espaciales observadas son relativamente débiles, ya que las estimaciones obtenidas para la media y el intervalo de confianza al 95% mediante técnicas geostadísticas y técnicas clásicas coinciden. Los bajos valores de concentración de Pb detectados en C. crangon concuerdan con los datos obtenidos para crustáceos decápodos en otras regiones. Para Zn los valores medidos en otras regiones se encuentran de manera consistente por debajo del intervalo de confianza del 95%, mientras que para Cu los valores observados son ligeramente superiores a los nuestros. Para la concentración de Cd en C. crangon los valores que se indican en la literatura son claramente superiores a la concentraciones medidas en nuestro estudio, mientras que para Ni no existen valores de comparación. Se concluye que con esta aproximación integrada a la valoración biológica, las concentraciones de metales pueden evaluarse de manera más precisa, así como las relaciones entre variables bióticas y abióticas

Heavy metals in crustaceans from the Iberian deep sea plain

Trace metals (Cd, Cu, Pb and Zn) were analysed in different well-defined mixed copepod and euphausiid samples as well as in individually analysed decapods collected during a cruise on board “RV Walther Herwig III” to the Iberian Deep Sea Plain in March and April, 2002. We found a substantial interspecific heterogeneity with partially high mean Cd levels in the decapods: 1.9 mg kg-1 dry weight in samples of the genus Sergia; 6.1 mg kg-1 in Acanthephyra pelagica (Risso, 1816) and Acanthephyra acanthithelsonis Bate, 1888; 10.7 mg kg-1 in Bentheogennema intermedia (Bate, 1888); 14.9 mg kg-1 in Benthesicymus iridescens (Bate 1881) and 16.3 mg kg-1 in Systellaspis debilis (A. Milne Edwards, 1881). The agreement of these high Cd concentrations with those reported for polar crustaceans, and Cu concentrations (17–56 mg kg-1) that indicate that the total metabolic requirements have probably not been met, support the hypothesis that the frequently reported Cd-anomaly in polar crustaceans might be extended to other relatively deep ocean waters like the Iberian Deep Sea Plain and that this might be related to a corresponding Cu deficiency. Zn concentrations in decapods from this study (52–80 mg kg-1) are within the worldwide range, which indicates that decapods are able to regulate their Zn body concentrations. Our preliminary data on mixed zooplankton samples suggest that Pb concentrations far below 1 mg Pb kg-1 might serve as a regional background value for comparison in biomonitoring studies. Results for Cd, Cu and Zn are largely within the reported range, especially for data from the Central and Southern North Sea

Heavy metals in zooplankton and decapod crustaceans from the Barents Sea.

Trace metals (Cd, Cu, Pb and Zn) were analysed in zooplankton samples and decapod crustaceans collected on cruises of "RV Walther Herwig III" to the Barents Sea (Summer 1991, 1994 and 2000). We found a substantial spatial heterogeneity in the decapod crustacean Pandalus borealis, with increasing Cd concentrations from the south (North Cape Bank; 0.7 mg kg super(- 1) DW) to the north (north of Svalbard; 4.7 mg kg super(- 1)), supporting the hypothesis that the frequently reported Cd-anomaly in polar crustaceans might be extended to the Barents Sea. Regarding various crustaceans and zooplankton collectives (2000) a distinct interspecific heterogeneity of metals was obvious, with lowest Cd concentrations in euphausiids and chaetognaths and highest ones in decapods and hyperiid amphipods; lowest Cu concentrations in chaetognaths and copepods and highest ones in euphausiids and decapods; and lowest Zn concentrations in euphausiids and decapods and highest ones in some copepods. For Pb many values were below or close to the limit of detection, suggesting that Pb concentrations about 0.4 mg kg super(- 1) might serve as a regional background value. Results for Cd, Cu and Zn in copepods of this study are largely within the reported range, but high Cd concentrations in copepods from summer in contrast to reported lower ones during winter/spring may be related either to changing accumulation strategies of the copepod species involved or to seasonally changing Cd absorption in copepods from food