Speciation of copper and responses of the marine diatom Ditylum brightwellii upon increasing copper concentrations

THE RELEASE OF COPPER‐COMPLEXING LIGANDS BY THE BROWN ALGA FUCUS VESICULOSUS (PHAEOPHYCEAE) IN RESPONSE TO INCREASING TOTAL COPPER LEVELS

“…The conditional stability constants measured previously for ligands exuded by other marine algae have varied between 10 7 and 10 13 (Florence and Stauber 1986, Seritti et al 1986, Brown et al 1988, Morelli et al 1989, Robinson and Brown 1991, Gerringa et al 1995b). The only other study measuring a Cu-complexing ligand exuded by a macroalgal species (Ectocarpus siliculosus (Dillwyn) Lyngbye, Phaeophyceae) resulted in a ligand class with conditional stability constants of 10 9.8 -10 10.2 (Sueur et al 1982).…”

“…Algae and bacteria are known to release extracellular Cu-complexing ligands (Sueur et al 1982, Seritti et al 1986, Florence and Stauber 1986, Brown et al 1988, Morelli et al 1989, Moffett et al 1990, Robinson and Brown 1991, Harwood and Gordon 1994, Gerringa et al 1995b, Moffett and Brand 1996, which result in decreased free-Cu concentrations being observed in the culture media or surrounding seawater. The function of these released exudates is not known for certain, although there is some suggestion that, at least for bacteria, the ligands are released to reduce the toxicity of Cu in the surrounding water Gordon 1994, Moffett andBrand 1996).…”

Toxicity and bioaccumulation of copper in three green microalgal species

“…Enteromorpha, which is frequently used as an indicator species for heavy metal contamination, contained relatively great concentration of Cu (Rijstenbil et al, 1998a,b). The chelation removal of heavy metals from the cell surface after the binding of Cu with organic complexes (including cell exudates) is another possible mechanism for the detoxification of metal ions (Xue et al, 1988;Xue and Sigg, 1990;Rijstenbil et al, 1994;Gerringa et al, 1995).…”

“…Internal metal immobilization by the formation of copper bodies can also occur (Nassiri et al, 1997). Binding to organic complexes, especially cell exudates, is another possible mechanism regulating the detoxification of metal ions (Xue et al, 1988;Xue and Sigg, 1990;Rijstenbil et al, 1994;Gerringa et al, 1995). It has been reported that microalgal production of glutathione, thiols or superoxide dismutase activity (SOD) can be stimulated by copper, which may also be a defense mechanism against copper toxicity (Rijstenbil et al, 1994(Rijstenbil et al, , 1998aRijstenbil and Wijnholds, 1996;Okamoto and Colepicolo, 1998;Leal et al, 1999).…”

The Toxicity of Copper(ii) Species to Marine Algae, With Particular Reference to Macroalgae

“…The ligands exuded by algae have consistently lower conditional stability constants ( Table 5 ) . In culture, the release of ligands has been associated with the stationary phase or just prior to the stationary phase of algal blooms (Mcknight and Morel 1979), although, more recently, release of complexing ligarids by microalgae has been associated with cell lysis (Gerringa et al 1995b). There does not appear to be any consensus of opinion as to what purpose the exudation of complexing ligands might serve.…”