Field contamination of the starfish Asterias rubens by metals. Part 1: Short‐ and long‐term accumulation along a pollution gradient

Abstract

The accumulation of Cd, Pb, Zn, and Cu in the starfish Asterias rubens was studied in a Norwegian fjord characterized by a gradient of metal pollution in the sediments, ranging from very high metal concentrations at its head to much lower levels at its opening. The concentrations of metals in starfish from natural populations along the gradient (long-term accumulation) and in starfish that were transferred up the gradient (short-term accumulation) were compared. At long-term, Cd and Pb accumulations by starfish living at normal salinity (30/1000) were related to the level of contamination of the environment while Cu and, to a lesser extent, Zn accumulations appeared strictly controlled. At short-term, Pb was accumulated steadily, Cd and Zn were accumulated transiently in the pyloric caeca (fast compartment), and Cu was not accumulated at all. Depuration experiments (transfer down the gradient) showed that Cd and Pb were efficiently eliminated from the pyloric caeca but not from the body wall (slow compartment). It is concluded that Pb is chronically accumulated, without apparent control, Cd is subjected to a regulating mechanism in the pyloric caeca which is overwhelmed over the long-term; Zn is tightly controlled in the pyloric caeca and Cu in both pyloric caeca and body wall. A distinct color variety of starfish is restricted to the low salinity (22-26/1000) superficial water layer. This variety showed a different pattern of metal accumulation over the long-term. This pattern is attributed to the particular hydrological conditions prevailing in this upper layer.

Structure of Sediment-Associated Microbial Communities along a Heavy-Metal Contamination Gradient in the Marine Environment

“…1 (in this study, station S3 is different from station S3 of previous studies [15]). S1 was located 100 m away from a zinc smelter and was the most heavily contaminated site (15,68). S2 was located in front of a titanium smelter, with S3 12 km further north and S4 in the neighboring fjord in the direction of the open sea.…”

“…The sampling stations (S1 to S4) were disposed as represented in Fig. 1 (in this study, station S3 is different from station S3 of previous studies [15]). S1 was located 100 m away from a zinc smelter and was the most heavily contaminated site (15,68).…”

“…Although inputs were significantly reduced in 1986, heavy metals in sediments still show a remarkable gradient from high concentrations in the inner fjord (station S1) to background levels at the opening of the fjord (station S4) ( Fig. 1) (15,68). Mean metal concentrations determined in the total sediments of S1 in 2000 were, in milligrams per kilogram (dry weight), 60 for Cd, 100 for Cu, 800 for Pb, and 100 for Zn (15).…”

“…1). This fjord displays very high levels of heavy metals in the sediments, which are the result of the discharge of considerable amounts of Zn, Cd, and Pb (since 1920) by smelters located at the head of the fjord (15,61,68). Figures for 1980 indicated that 1,387 tons of Zn, 329 tons of Pb, and 14.6 tons of Cd were discharged into the fjord during that year alone (68).…”

“…1) (15,68). Mean metal concentrations determined in the total sediments of S1 in 2000 were, in milligrams per kilogram (dry weight), 60 for Cd, 100 for Cu, 800 for Pb, and 100 for Zn (15). These concentrations are 10 to 30 times higher than those reported in sediments sampled in the most contaminated areas of the southern North Sea (14) and up to 60 times higher than the ecotoxicological assessment criterion of OSPAR (Oslo and Paris Commission for the Protection of the Marine Environment of the North-East Atlantic), which is defined as the concentration level above which concern is indicated (reports are available at www.ospar.org).…”