The Measurement of Adenosine Triphosphate in the Ocean and its Ecological Significance

A method is described for the quantitative determination of adenosine triphosphate (ATP) in quantities as low as 10-4 μ g. Using sample volumes of less than 2 liters, two profiles of ATP concentration have been made down to 1,025 m off the California coast. The biomass of living material in the water has been estimated from these data, using the ATP content of laboratory cultured microorganisms as indicators of endogenous ATP levels. When equated to numbers of bacteria, the ATP levels found at various depths in the ocean indicate bacterial populations between 50-2,000 times those found by plating techniques.