Reproduction of aquatic hyphomycetes at low concentrations of Ca2+, Zn2+, Cu2+, and Cd2+

Abstract

Maple leaf disks were conditioned in a stream for three weeks and then aerated for 2 d in distilled water to induce fungal sporulation. The release of aquatic hyphomycete spores increased when the water was supplemented with low concentrations of Ca(2+) (5 µg/L), Zn(2+) (2.5 µg/L), Cu(2+) (0.5 µg/L), or Cd(2+) (0.125 µg/L). Higher supplement concentrations inhibited sporulation. Over the concentration range used, the sporulation response was generally best described by a quadratic regression, suggesting a biphasic or hormetic response. A similar pattern was found with the number of fungal species as the dependent variable. Anguillospora filiformis and Anguillospora longissima were generally least inhibited by metal supplements, and Ca(2+) was the least and Cd(2+) the most toxic metal. Combinations of metals had a more severe effect on fungal sporulation than predicted from addition of the effects of the metals in isolation. The biological significance of the hormetic response is unclear; however, acknowledging it is clearly relevant for establishing guidelines or recommendations in toxicology.

Inorganic fungicides as routinely applied in organic and conventional agriculture can increase palatability but reduce microbial decomposition of leaf litter

“…; Duarte, Pascoal & Cássio ) may have reduced the competitive pressure for fungi resulting in the higher fungal biomasses. This may also explain the observed trends to an increased fungal spore production (Roussel, Chauvet & Bonzom ; Sridhar & Bärlocher ) and a higher number of fungal species on Cu‐exposed leaf discs (Table ). Likewise, Bundschuh et al .…”

“…3a,b,c,e; Duarte et al 2008;Duarte, Pascoal & C assio 2009) may have reduced the competitive pressure for fungi resulting in the higher fungal biomasses. This may also explain the observed trends to an increased fungal spore production (Roussel, Chauvet & Bonzom 2008;Sridhar & B€ arlocher 2011) and a higher number of fungal species on Cu-exposed leaf discs (Table 2). Likewise, Bundschuh et al (2009) assumed the promoted fungal growth on antibiotics-exposed leaf material to be the result of negative effects on the bacterial community.…”

Hormesis: Biphasic Dose-Responses to Fungicides in Plant Pathogens and Their Potential Threat to Agriculture

“…Thereafter, for the purposes of this book, we will focus on chemical hormesis alone. Some of the most familiar examples of biphasic dose-responses include vitamins, alcohol, essential minerals, and many drugs (16,17,18,19,20). Hormesis has been measured using diverse endpoints in multiple biological systems (8).…”

Development of a groundwater fungal strain as a tool for toxicity assessment

“…Knowledge of the impact of pollutants on filamentous fungi in both terrestrial and surface aquatic systems is wide. Organic and mine pollutants, for instance, generally cause a decline in species richness, activity, and/or reproduction rates in fungi from surface waters [6][7][8]. Similar trends have also been recorded in hydrocarbon-contaminated groundwater systems [9].…”