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Hansen Johnson of Bates College, a student in the MBL's Semester in Environmental Science, works in the laboratory's sterile hood with blue-green algae as part of his experiment examining algal growth in water containing a range of nitrogen and phosphorus concentrations.

Semester in Environmental Science Students Present Independent Research at Symposium

After 10 weeks of intensive course work and five weeks of independent research, the students in the MBL's Semester in Environmental Science (SES) program presented the results of their projects at a symposium on December 16 at MBL's Speck Auditorium.

The symposium featured 15-minute presentations of research projects that ranged from a survey of Falmouth homeowners' lawns to study the effects of fertilizer, to a project that involved extracting cyanobacteria (blue-green algae) in the laboratory to test its ability to capture nitrogen.

Hansen Johnson of Bates College won the MBL Associates Award for Excellence in Independent Research for his project,"Resource limitation affects productivity and heterocyst formation in nitrogen-fixing cyanobacteria." He studied the growth response of Anabaena (a filamentous cyanobacterium) to a range of very high and very low nitrogen and phosphorus concentrations in water. Specialized cells in the filaments of this blue-green alga can capture ("fix") nitrogen gas from the air and use it for the alga's own growth when nitrogen is scarce, and Hansen tested whether that ability might be limited by phosphorus availability. Both nitrogen and phosphorus are common pollutants in water bodies world-wide, and blooms of many types of blue-green algae are known to occur in response to increased nutrients.

During the SES program, Hansen and his classmates used a curriculum that approaches environmental science from an ecosystems perspective, studying the interaction of biology, chemistry and geology across the landscape. SES students conduct research in local sites on Cape Cod such as freshwater ponds, brackish estuaries and a forest irrigated with wastewater effluent from our municipal sewage treatment plant, but the problems addressed during the semester are by no means local; they include impacts of land use change, disruption of the global nitrogen cycle, climate change, fossil fuel emissions and carbon cycling, deforestation and over exploitation of fisheries.

The SES program is based at the Ecosystems Center and is now in its fifteenth year. This year's class has 23 students from colleges across the nation: Mount Holyoke, Ripon, Brown, Franklin & Marshall, Harvard, Bates, Colorado, Connecticut, Colby, Allegheny, Carleton, Clark, Villanova, Hampshire, Harvey Mudd, Grinnell, and Washington and Lee.

SES Symposium Schedule