Bacterial Nitrogen Fixation in a Polluted Coral Reef Flat Ecosystem, Kaneohe Bay, Oahu, Hawaiian Islands

Abstract

Benthic nitrogen fixation was investigated in Kaneohe Bay, Oahu, Hawaiian Islands, which receives secondary sewage from two treatment plants. The range of nitrogen fixation rates (2 to 10 ng N2g-l hr-l) was similar to those reported by other workers for a variety of benthic systems. Enrichment cultures prepared from sediment samples from five stations revealed the existence of several distinct physiological types of nitrogen-fixing bacteria. It was found that 50 percent of the bacterial fixation in the southern sector was light-dependent. There was a significant relationship between the numbers of nitrogen-fixing bacteria detected and rates of nitrogen fixation measured in the sediments.