축 라군의 미생물 생태계: 일차 및 박테리아 생산력

Abstract

The primary and bacteria productions of different habitats within the Chuuk Lagoon show distinct characteristics. The primary production of general lagoon water is dominated by picoplankton and nitrogen fixing phytoplankton such as Trichodesmium can stimulate primary production by picoplankton. Such results indicated that high production rate observed in the lagoon ecosystem overcoming various limitation of oligotrophic tropical environment and well adjusted as a tropical oasis. The high primary and bacterial production in mangrove environment might be the result from the supply of organic matter from various sources(fallen leaves, excretion of fish, etc.) and the supply of inorganic nutrients by bacterial remineralization processes. Nutrient outwelling processes in the mangrove system seemed to increase primary production and induce changes in phytoplankton assemblages dominated by increased diatoms. For seagrass dominant system, bacterial production has increased whereas primary production remained similar to surrounding general lagoon water. The seagrass themselves and microalgae adhere to seagrass leaves have high primary productivity(unpubished data), however, activities of primary producers competing for inorganic nutrients in the water column did not show much increase. However, with relatively high primary production, seagrass systems are used as essential habitats for various organisms with relatively high biological activities which may increase production of organic matters eventually increasing the bacterial production. The results from this study, so far, suggest that different habitats within the lagoon have different biological process which stimulates microbial production of each habitat. The results also indicated that stimulated microbial production of these various habitat environment play significant role in maintaining the high biological production and high biodivserity of the lagoon ecosystem.