Bacterial Substrates and Productivity in Marine Ecosystems

Abstract

The classic food pyramids in sea consist of a plant-microbial base nurtured by sunlight or debris, which is consumed by invertebrates, which in turn are eaten by carnivores. This food pyramid can be based on neustonic ecosystems at sea-air interface, on planktonic ecosystems living free in water, on epibiotic ecosystems attached to surfaces, or on benthic ecosystems within sea floor. As a result of feeding processes in and on each of these ecosystems, a very large amount of excrement is released into environment. As organisms are eaten and transformed from ingesta to feces or pseudofeces to sedimenting debris, or die to follow a similar fate, they form a fifth and often overlooked or misunderstood series of fecal-sestonic ecosystems. If it were not for bacteria which solubilize particulate matter and utilize soluble matter, and bacteria-eating protozoa and larger forms that feed upon them, waste products resulting from excretion, defecation, and death could be considered a loss to food pyramid (234). But bacteria and bacteria-eating forms are present in considerable numbers throughout lengths and depths of seas and occur as indispensable components in all five ecosystems. The bacterial-protozoan partnership that utilizes dissolved carbon (DOC) and particulate carbon (POC) is not separate from the mainstream of as believed by Strickland (234), but is a mechanism for keeping DOC and POC in mainstream of tropho-dynamics by connecting ecosystems and maintaining long-term steady state of life in sea. A detailed reevaluation of nature of suspended and sedimenting debris, also known as POC or seston, is needed because currently accepted notions may be incorrect and preventing development of more accurate working hypotheses. Evaluations of nature of POC in seawater (72, 185) assume that most of this material is produced from DOC that comes out of solution to form organic