62 



Annals of the Smithsonian Institution 2000 



cal microscopy center offered two new courses in addition to 

 repeat performances. 



Smithsonian Environmental 

 Research Center 



Ross Simons, Director 



The Smithsonian Environmental Research Center (SERC) is 

 a major international research and education center dedi- 

 cated to understanding the ecological dynamics and human 

 impacts in land/sea interactions of the coastal zone. SERC 

 carries out research from Prince William Sound, Alaska, to 

 the Antarctic Ocean; and from the farmlands of the Chesa- 

 peake Bay watershed to the Mangroves of Central America. 



The former director of SERC, Dr. David L. Correll retired 

 in November 1999, leaving an important legacy of scientific 

 and administrative accomplishments. Correll joined the 

 Smithsonian Institution in 1962. He was instrumental in 

 founding SERC and beginning many of the long-term stud- 

 ies there that continue today. He has produced about 140 

 scientific publications. Among his scientific contributions 

 are numerous pioneering studies of the chemical flows link- 

 ing air, land, and sea. 



Human activities have increased flows of plant nutrients 

 from land causing excessive growth of phytoplankton 

 (microscopic algae) in estuaries such as Chesapeake Bay. A 

 study led by Dr. Charles Gallegos analyzed a massive phyto- 

 plankton bloom in upper Chesapeake Bay triggered by runoff 

 of nutrients during unusually rainy conditions during April 

 and May 2000. Special instruments measured the absorption 

 of light by phytoplankton, dissolved organic matter, and 

 suspended sediments. The separate effect of each of these 

 components on light penetration was determined using math- 

 ematical procedures developed at SERC. During the bloom, 

 light absorption by phytoplankton exceeded that by both of 

 the other components for a period of about two weeks. In- 

 creased light absorption by decay products of the phyto- 

 plankton bloom lasted another two weeks. Reduced light pen- 

 etration caused by excessive growrh of phytoplankton has been 

 the primary cause of loss of underwater grasses in Chesapeake 

 Bay. Bay grasses are widely believed to be an indicator of over- 

 all health and water quality of the Bay. The research was 

 funded by the Coastal Intensive Site Network (CISNet) pro- 

 gram of the U.S. Environmental Protection Agency. 



SERC is also studying another important aspect of under- 

 water light: the potential harmful effects of ultraviolet (UV) 

 radiation. The intensity of UV radiation at the sea surface 

 will increase if the UV-absorbing layer of stratospheric ozone 

 continues to thin. To learn more about the effects of UV 

 radiation, a team of SERC scientists led by Dr. Patrick Neale 

 has developed a solar simulator to expose phytoplankton to 

 controlled amounts of UV radiation. Exposures are precisely 

 conrrolled as to duration and intensity of UV. Subsequently 

 DNA damage is measured. Mathematical models of the rela- 



tionship between UV and DNA damage are then developed 

 to predict effects of changes in solar UV radiation. 



Wetlands provide important habitats for plants and ani- 

 mals while acting as natural filters removing pollutants, such 

 as plant nutrients, from runoff. A team of SERC scientists, 

 including Drs. Whigham, Weller, and Jordan, collaborated 

 with The Nature Conservancy to assess the environmental 

 health of non-tidal wetlands in the Nanticoke River water- 

 shed. The EPA-funded study has identified ecological 

 indicators of the condition of wetlands and of their potential 

 to remove nitrogen from runoff. By combining observations 

 of dozens of wetlands with geographic information about the 

 watershed, the researchers will project the assessment of wet- 

 land condition over large spatial scales. 



SERC studies of tropical mangrove forests around the 

 world are exploring the effects of human-caused nutrient en- 

 richment on these critically important coastal ecosystems. 

 Mangrove forests dominate the world's tropical and subtrop- 

 ical coasts, paralleling the geographical distribution of coral 

 reefs. Ecological processes in these forests are influenced by 

 inputs from the land, sea, and sky, which result in extreme 

 fluctuations of flooding, salinity, temperature, light, and 

 nutrient availability. Mangrove-associated organisms have 

 specialized physiological and structural adaptations that sus- 

 tain them in this variable environment. Human-caused 

 nutrient enrichment is one of the major global threats to 

 these coastal ecosystems. Experiments show that nutrients 

 are not uniformly distributed among or even within man- 

 grove forests. Soil fertility can switch from nitrogen to 

 phosphorus limitation across narrow gradients. Our research 

 explores the relationships among physical and chemical fac- 

 tors, nutrients, microbes, trees, and elemental cycling on 

 offshore mangrove islands in Belize. This NSF-funded proj- 

 ect led by Dr. Ilka Feller examines the interactions between 

 the environment and organisms to determine how changes in 

 nutrient inputs from natural, agricultural, or urban sources 

 might alter the delicate balance among these ecosystem 

 components. Mathematical models will help us predict the 

 contribution that biocomplexity makes to the ability of 

 mangrove ecosystems to survive both natural and anthro- 

 pogenic disturbances. 



A SERC study directed by Dr. Bert Drake used open- 

 topped chambers to expose stands of scrub oaks to elevated 

 levels of atmospheric carbon dioxide at a field site in 

 Florida. The responses of oak forest show how similar 

 ecosystems may reacr to the global increase in carbon diox- 

 ide caused by deforestation and the burning of fossil fuels. 

 Elevated carbon dioxide stimulated growth in Florida scrub 

 oak and reduced water loss. Because of these combined ef- 

 fects, the scrub oak tolerates severe drought much better if 

 it also is exposed to elevated carbon dioxide. This may mean 

 that as the climate warms, the elevated carbon dioxide will 

 promote survival of plants in very hot, dry environments, 

 possibly good news for the plants. However, the research 

 also showed that insects must eat more the foliage grown 

 in elevated carbon dioxide than in present normal ambient 

 carbon dioxide, thus exposing themselves longer to their 



