Substrate Capture by Marine Heterotrophic Bacteria in Low Nutrient Waters

Abstract

Except in coastal areas and some isolated marine environments seawater can be classified as oligotrophic or even ultraoligotrophic. If the nearshore values for the dissolved organic carbon (DOC) are ignored, the DOC ranges from 0.3 to 1.2 mg C·liter−1 and in the deep sea, ca. 0.5 mg C·liter−1 (Riley and Chester 1971). Other values are cited by various authors in review articles dealing with organic matter in seawater (Menzel 1974, Williams 1975; Duursma 1965; Wangersky 1978) and in each instance, the values for DOC are low. The amount of particulate organic carbon (POC) is exceeded by the DOC by a factor of 10 to 20 (Riley and Chester 1971) and its value will depend on various factors. Approximately 1/5 of the particulate organic fraction is composed of living organisms. Although the amount of DOC and POC is not very great per unit volume, the total amount in the entire oceans is extremely huge. The reservoir of DOC and POC in the ocean is placed at 655 × 109 tons and 14 × 109 tons respectively, assuming the values of 0.5 mg C·liter−1 and 10 µg C·liter−1 respectively (Menzel 1974). The turnover time is 3, 300 years (Menzel 1974).