WATER CHEMISTRY AND SPORULATION BY AQUATIC HYPHOMYCETES

Maple leaf disks were exposed in a softwater stream for two weeks and then aerated for 2 d in water to induce spore production by aquatic hy phomycetes. Sporulation was inhibited by the addition of yeast extract or leaf leachate (up to 2.5 g l(-1)) to the sporulation water. With l eaf leachate, but not with yeast extract this effect was neutralized b y the addition of 50 mg l(-1) of CaCl2. Sporulation increased at inter mediate concentrations of several inorganic compounds (CaCl2;KH2PO4/K2 HPO4;NaNO3;NaCl). It increased at low concentrations (1-3 g l(-1)) of an artificial seasalt mixture, was much reduced at 7.5 g l(-1) and abs ent at 15 g l(-1).