Abstract Detail

Ecological Section

Malcolm, Katalin [1], Dighton, John [2], Barkay, Tamar [3].

Influence of mercury deposition on fungal phylloplane communities and litter decomposition.

Mercury is a highly toxic heavy metal and considered a global pollutant due to its yearlong residence time in the atmosphere. Leaves sequester atmospheric mercury, and subsequently deposit mercury to the soil through litterfall. Leaf surfaces (phylloplane) host a diverse micro-fungal community on a relatively restricted niche. These phylloplane fungi are exposed to mercury pollution through atmospheric deposition and are drivers of decomposition following leaf senescence. The role of fungi in the mercury cycle is poorly understood, and little research has examined mercury and fungal phylloplane interactions. Our research seeks to answer the following questions. When leaves are exposed to mercury deposition, how are the fungal phylloplane communities affected? Does pre-exposure to mercury affect leaf decomposition and the community of fungal decomposers?
To test how the fungal phylloplane communities were affected by mercury, we applied known concentrations of a mercuric chloride water solution to individual leaves of blueberry plants. The epiphytic fungi were cultured directly from the leaves; pure isolates were morphologically and molecularly identified. We found that mercury did not significantly affect fungal phylloplane diversity, and that time was a more influencing factor. Common species (e.g. Epicoccum sp., Cladosporium sp.) were frequently isolated regardless of mercury treatment. It is our goal to assess the fungal phylloplane community by conducting a genetic analysis (Denaturing Gradient Gel Electrophoresis) to determine if there are changes to the community not detected by culture-based methods. The fungal phylloplane community appears resistant following exposure to mercury deposition. However, individual species exhibit changes in hyphal growth rate when exposed to mercury-amended media. Preliminary data indicates that mercury suppresses fungal growth, but the effect appears to be species dependent. Pairwise fungal interactions show that mercury may affect the competitive abilities of some species.
To determine if pre-exposure to mercury affected leaf decomposition, leaves that received the mercuric chloride application were decomposed on the forest floor in litterbags. Leaves exposed to the higher mercury treatment (0.053 μg/leaf) exhibited slowed decomposition between 168 and 336 days, but overall decomposition was not significantly different when compared to the control leaves. Leaves exposed to the lower mercury treatment (0.013 μg/leaf) decomposed significantly faster (GLM, p<0.05) than the high mercury treatment and the control treatment. This suggests that pre-exposure to low levels of mercury may influence leaf decomposition. Further investigation by molecular analysis will determine if there were changes in fungal succession during decomposition.

1 - Rutgers University, Ecology, Evolution and Natural Resources, 14 College Farm Rd. , New Brunswick , NJ, 08901, USA
2 - Rutgers University, Biology, Science Building, 315 Penn Street, Camden, NJ, 08102, USA
3 - Rutgers University, Biochemistry and Microbiology, 76 Lipman Drive, New Brunswick, NJ, 08901, USA

Keywords:
phylloplane
mercury
decomposition.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Hall D/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 5:30 PM
Number: PEC013
Abstract ID:174
Candidate for Awards:MSA Best Poster Presentation Award by a Graduate Student