Productivity of Epipelic Algae in Tundra Ponds and a Lake near Barrow, Alaska

The biomass and productivity ((14)C) of epipelic benthic algae were measured in several tundra ponds and in a lake near Point Barrow, Alaska. In the ponds (50 m diam X 20 cm deep) the epipelic algae (mostly Chlorophyta and Cyanophyta) are most abundant in the upper 2 cm of sediment but their total biomass is low (0.5—1.5 g C°m(—2)) and no surface mat of cells forms, largely because of the continuous mixing of the flocculent surface sediments by a variety of benthic invertebrates. Epipelic photosynthesis is limited to a 3—mo thaw period (June through August) and has a single broad peak in mid—July of ° 200 mg C°m(—2)° day(—1). Epipelic production ranged from 10—4 g C m—2 yr—1 (1971—1973), compared to 1 g C m—2 yr—1 for the pond phytoplankton. In contrast, epipelic production in nearby Ikroavik Lake (12 km2 X 2 m deep) was only 2.3 g C°m(—2)°yr(—1) because of lower light intensities at the sediment surface, lower water temperatures, and a shorter ice—free period than in the ponds.