Aquatic fungi and their role in leaf breakdown

1. Aquatic fungi and their role in leaf breakdown Katie Seymore

2. Outline • Two different aquatic fungi • Leaf breakdown and fungi • Bacteria and fungi relationship • The essential role of leaf conditioning

3. Two key groups • Aquatic hyphomycetes and aero-aquatic fungi • Form-class fungi • Most Ascomycetes, fewer Basidiomycetes, one Oomycete • Secondarily adapted to aquatic life • Convergent evolution events • Similar ecological roles • Leaf breakdown

4. Aquatic hyphomycetes • First described by Ingold in the 1940’s • Produce and release spores underwater • Mostly in streams- moving, oxygenated water Conidia

5. Aero-aquatic fungi • Described by Beverwijk 1950’s • Amphibious • Propagules trap air and float for dispersal • Mostly in temporary waters, low oxygen

6. Amphibious fungi Fall- conidia germinating Winter/spring- grow Summer- make propagules

7. Propagules • Trap air • Hydrophobic encrustation • Many different forms

8. Leaf Breakdown • Important ecological role • Release nutrients to aquatic ecosystems • Increase leaf’s N content • Lowers leaf mass • Amount of lignin (polymer in cells walls) content controls how fast leaf decomposes • available carbon • Tannins amounts also big deal (phenol compounds)

9. Fungi and Leaves • Overall generalists • Can specialize • Combined exoenxzymes of all fungi on a leaf help speed breakdown • Linked mycelium • Two different leaves • Help by Sharing • Harm by sending incorrect cues to healthy mycelium

10. Bacteria and Fungi • Bacteria are often talked about, but have only a small role • Bacteria cannot penetrate leaf, only on outside • Fungi are 95% of microbial biomass • Fungi perform better without bacteria • Bacteria has little growth without the presence of fungi • secondary compounds

11. Fungi and Leaf Conditioning • Key links in the food web • Breakdown tough compounds in the leaves • Different leaves condition at different times • Make leaves suitable for detritivores, like caddisflies

12. Caddisflies and Fungi • Caddisflies consume leaf parts • but really, the fungi in the leaf is more nutritious then the leaf itself • Caddisflies taste test leaves • Will avoid unconditioned parts, eat only the best spots

13. Unhelpful fungi • Leaves can be over conditioned by fungi • Out of nutrients • Fungi dead • Mycotoxins • Instead of conditioning the leaf, some fungi make it less palatable • Defense against getting eaten

14. Fungi are important for ecosystems • Allochthonous material very important for aquatic food webs • Organisms in vernal ponds have limited time to grow before ponds dry out, so any increase in food quality helps! • Fungi play a role in food availability throughout the year with different conditioning times for different leaves

15. Conclusion • Two main forms of aquatic fungi • Awesome convergent evolution • Important for food supply in aquatic ecosystems • Key to nutrient release and detrital breakdown

16. Questions?

17. Works cited Pictures • http://www.botanik.univie.ac.at/mycology/images/PosterOslo.jpg • footage.shutterstock.com • http://ww2.coastal.edu/vgulis/conidia.htm • http://www.mycolog.com/chapter11b.htm • http://www.mycolog.com/chapter11b.htm • www.thinklongislandfirst.com • http://www.naturalheritage.state.pa.us/VernalPool_Ecology.aspx • http://fungi.life.illinois.edu/about/mitosporic_fungi • http://super-mario-world.webnode.com.br/products/random-images-4/

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