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The common starfish, Asterias rubens, occurs in fluctuating environments in the North Atlantic. To better understand energy allocation dynamics, we recorded gonad, body wall, and pyloric caeca (storage organ) indices between 2000 and 2004 from three different habitats. We applied a Fourier transform to the data to evaluate and compare the seasonal variation in these indices. Specific effects of emersion and salinity variation were examined in two laboratory studies. Differences in energy allocation were found between sites and temporally within sites. Food availability appeared to be the most important factor controlling allocation dynamics while fluctuating salinity and/or emersion had a significant but smaller impact. Only severe food shortage reduced reproductive investment indicating a preferential energy allocation to gonads. This study is the first to encompass a broad range of populations over several reproduction cycles and emphasizes the ability of A. rubens to adapt to a fluctuating environment. Copyright © Marine Biological Association of the United Kingdom 2012., IF: 1,056, SCOPUS: ar.j, info:eu-repo/semantics/published

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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‰) 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‰) 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., IF: 2,462, SCOPUS: ar.j, info:eu-repo/semantics/published

To study the effects of metals on starfish in field conditions, immune responses were measured in starfish from natural populations along a metal pollution gradient (long-term contamination) and in starfish that were transferred up the gradient (short-term contamination). Coelomic amoebocyte concentration (CAC) and production of reactive oxygen species (ROS) by amoebocytes were measured in two varieties of Asterias rubens occurring in the fjord: The black variety which lives only in the low salinity upper waters (22-26‰) and the red variety which live both in the upper layer and in the deeper layer characterized by a salinity close to that of seawater (30‰). The studied immune responses were stimulated in starfish living along the metal pollution gradient according to the contamination of these starfish by cadmium. However, the sensitivity of these responses toward metals appeared to be strongly modulated by the salinity stress. In red starfish living at 30‰ and transferred up the contamination gradient, the immune responses were inhibited and closely followed the short-term accumulation of metals in the animal organs. Starfish transferred down the gradient did not recover normal immune responses in the short-term and appeared highly sensitive to caging stress. It is suggested that the impact of metals on the immune responses of A. rubens in field conditions occurs in three phases. Short-term inhibitory effects are exerted by a direct action of metals on the immune cells and are followed by a recovery due to the induction of protective mechanisms. Eventually, when these mechanisms are overwhelmed by a long-term contamination, indirect and durable stimulatory effects on the immune responses appear due to a global disruption of the animal physiology., IF: 2,462, SCOPUS: ar.j, info:eu-repo/semantics/published

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