Fallen autumn foliage of Downy Birch (Betula pubescens) floating on the surface of an acid bog lake. The submerged vegetation is all Sphagnum moss, which thrives under these highly acidic conditions (pH 3.5 in this case).
A side effect of the acid precipitation is when the acid makes humic substances precipitate to leave crystalline clear water. All fish and most of the aquatic animal life will disappear simultaneously, so the clarity costs the ecosystem dearly.
This photo was acquired end of September at a time first snow already had fallen and the lake surface was about to freeze over. Light levels were extremely low and even more so under water, so the tripod-mounted Nikonos with its 15 mm f/2.8 UW-Nikkor lens exposed the scene for several minutes. Keeping myself motionless in the ice cold water for such exposures was a challenge, but the outcome might be worth the efforts. I did have to repeat a number of times though due to floating foliage being shifted by air currents.
