Photos & Maps



The Plum Island Estuary Microbial Observatory (PIMO), located at the Plum Island Estuary LTER site in coastal Massachusetts, identifies prokaryotes in salt marsh sediments and plankton and determines their role in controlling major ecosystem processes.

PIMO is closely linked to the LTER project. The LTER research addresses how changing inorganic nutrient supply and the quality and quantity of organic matter interact to affect estuarine trophic structure. The Microbial Observatory uses LTER data to place microbial communities into the larger context of their physical and chemical environment. In turn, the LTER research gains detailed knowledge about the microbial communities underlying the processes and control parameters which it investigates.

In the salt marsh sediments, nitrogen and sulfur cycles influence all of the salt marsh biogeochemical cycles while sulfate reduction dominates decomposition. Therefore, the Observatory Project focuses on the microbes involved with the nitrogen and sulfur cycle with special attention to nitrification and sulfate reduction. This focus is possible because these P.I.s bring a suite of tools for culturing, molecular detection, and identification of nitrifying and sulfate reducing bacteria.

The Microbial Observatory carries out the following activities:

Identifies the microbes and microbial communities by means of culture and sequencing techniques.

Investigates the seasonal changes in the community structure with culture methods, denaturing gradient gel electrophoresis (DGGE), and environmental clone library sequencing of 16S rRNA genes.

Links functional genes and microbial populations responsible for specific processes with rRNA hybridization techniques.

Correlates the presence and activity of various populations with ecological measurements of major processes in the salt marsh.

Molecular surveys using functional genes and rRNA hybridization techniques are correlated with LTER measures of sulfate reduction and the nitrogen cycle. Carbon sources are identified with techniques using the d13C of phospholipid fatty acids specific to bacteria.

Salt marshes provide one of the best examples of a site where microbes build and shape an entire ecosystem. Cyanobacteria are the pioneer organisms in salt marshes; they initiate microbial mat communities on mudflats that prevent erosion, trap sediment particles, and elevate the surface of the sediments. When higher plants colonize the site, the microbes fix nitrogen, recycle organic matter and nutrients, oxidize sulfides, and provide food for higher trophic levels.

Salt marshes continue to be important models for basic microbiological and biogeochemical research. These systems are easily accessible. Their high process rates, large and diverse populations of functionally distinct microbes, and steep chemical and microbial gradients allow scientists to understand how microbial interactions and chemical cycles work. For example, many of our insights into the process and microbiology of sulfate reduction in the marine environment have come from the study of salt marshes.

The value of salt marshes in teaching and education is well established. Microbiology textbooks emphasize microbial mats. Students of the Microbial Diversity Course at the MBL in Woods Hole, associated with this Microbial Observatory, use the salt marsh as a "Microbial Rainforest" for the isolation and identification of a wide diversity of microbes. This course has introduced more than 600 students to the discipline of microbial ecology.

[Home] [Overview] [People] [Projects] [Protocols] [Data] [Photos & Maps] [Publications] [Links]