The factors controlling planktonic primary and secondary production in 22 meltwater ponds varying in chemical conditions, and in layers of stratified ponds

The importance of the large differences in chemistry in the ponds of the McMurdo ice shelf for their planktonic productivity was examined by comparing rates of primary (algal) production and secondary (bacterial) production in 22 ponds that varied from very fresh, low-nutrient environments to very salty, nutrient-enriched environments. Because the ponds stratify into layers, the production was also compared between layers in three ponds that were strongly stratified. The study involved estimations of productivity using radioactive 14C-uptake for algae and 3H-thymidine and leucine for bacteria, cell counts, and water nutrient and physico-chemical assays.