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Abstract Detail



Ecology/Pathology

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

The effects of mercury on fungal phylloplane communities.

Mercury (Hg) is a highly toxic metal that is considered a global pollutant.  The function of bacteria in the Hg cycle and Hg transformation is well documented.  However, the role of fungi in the Hg cycle is less understood.  Leaf surfaces (phylloplane) host a diversity of microfungi, are directly involved in the transition from atmospheric Hg and function as a pathway for Hg to reach the forest floor through litterfall.  Our analysis examines the effect of Hg deposition on fungal phylloplane communities and the impact of Hg on leaf litter decomposition.      The fungal phylloplane communities of blueberry plants (Vaccinium corymbosum) have been targeted for study.  Hg deposition was simulated in a laboratory greenhouse experiment by applying known concentrations of HgCl2 in a water solution to individual leaves by pipette.  The concentration of the solutions provided the three treatment levels (n=3), a control (0X), a low Hg concentration representative of ambient levels (1X) and a high Hg concentration four times higher than ambient levels (4X).  Following a single application, plants were stored under uniform greenhouse conditions in a randomized block design and leaves were sampled over a four month period.     Epiphytic fungi were isolated, cultured on PDA and identified by morphological characteristics and molecular techniques.  Based on morphological identification, the leaves treated with 4X Hg concentration revealed a slightly higher fungal community diversity (p<0.1) than compared to the control leaves (0X).  Pure fungal isolates were subjected to varying concentrations of Hg amended media to determine individual growth rates.  Species tended to exhibit slower growth rates at the highest Hg treatment (30 μM l-1) and were less affected at low to intermediate levels (0- 20 μM l-1).  Fungal resistance or tolerance to Hg was tested by measuring growth rates by pairwise competition studies.  Growth inhibition during competition is Hg concentration and fungal species dependent.  At leaf-fall, leaves were collected and litter bags (0.7g leaf material) were deployed in the forest to determine the impact of Hg on decomposition rates.  Ambient level Hg treated leaves (1X) decomposed faster than 0X leaves initially (90 days), and more rapidly than 4X leaves after one year.  The greenhouse study was repeated in year two with modifications to the Hg treatments (0X, 4X, 10X and 20X).


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1 - Rutgers University, Ecology and Evolution, 57 Highway 1, New Brunswick, NJ, 08901, USA
2 - Rutgers Pinelands Field Station, 501 Four Mile Rd, New Lisbon , NJ, 08064, USA
3 - Rutgers University, Biochemistry and Microbiology, 76 Lipman Drive, New Brunswick, NJ, 08901, USA

Keywords:
phylloplane
epiphytic
mercury
heavy metal.

Presentation Type: Offered Paper - Paper
Session: 11
Location: Room 103 AB/Kellogg Hotel and Conference Center
Date: Tuesday, June 10th, 2014
Time: 11:00 AM
Number: 11003
Abstract ID:25
Candidate for Awards:Graduate Student Oral Presentation Award


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