38 



Annals of the Smithsonian Institution 1999 



excavation and subsequent laboratory processing and storage, 

 through demonstrations, workshops, and lectures. 



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. 



SERC scientists recently published a series of journal arti- 

 cles on a 2 5 -year study of stream discharges of materials 

 from the Rhode River watershed. The studies, begun by Dr. 

 David Correll, revealed in unprecedented detail the relation- 

 ships between stream discharges and precipitation. Storms 

 had an especially big effect on particulate materials in stream 

 water. The establishment of a beaver dam on one watershed 

 led to significant retention of nutrients. Unexpected long- 

 term declines in discharges of silicate may reduce the growth 

 of silicate-dependent phytoplankton, which help support the 

 food chain in the Rhode River and Chesapeake Bay. 



Drs. Gallegos, Jordan, and Neale received a three-year, 

 $510,181 grant from the U.S. Environmental Protection 

 Agency (U.S. EPA) to become a pilot site in a network of 

 long-term, intensively monitored coastal index sites. The 

 Coastal Intensive Site Network (CISNet) is part of Phase II 

 of U.S. EPA's Environmental Monitoring and Assessment 

 Program (EMAP). CISNet is being established to provide a 

 network of "outdoor laboratories" at which research and 

 monitoring will be conducted to establish linkages between 

 observed changes in environmental stressors and concomi- 

 tant changes in ecological resources. The grant will allow 

 SERC scientists to supplement ongoing measurements of 

 nutrient fluxes from the watershed with new instrumenta- 

 tion to monitor estuarine optical properties, namely spectral 

 absorption and scattering coefficients. Research to interpret 

 the monitored data will focus on three areas: (1) research to 

 interpret estuarine optical properties in terms of the concen- 

 trations of water quality parameters that are indicative of 

 eutrophication and sediment pollution; (2) manipulative ex- 

 periments to establish the response of in situ concentrations 

 of water quality parameters to inputs of nutrients (both 

 watershed discharge and atmospheric deposition) and partic- 

 ulate matter on event to interannual time-scales; (3) process 

 level research to examine the effects of solar UV (and espe- 

 cially UV-B) radiation on nearshore plankton communities, 

 as influenced by estuarine optical properties. The research is 

 expected improve the environmental decision-making 

 process, by establishing comparative mechanisms by which 

 nutrient inputs by watershed discharge and precipitation af- 

 fect trophic structure of an estuary, resulting in measurable 



and interpretable variations in estuarine optical properties on 

 multiple time-scales. 



One SERC program investigates the harmful effects of so- 

 lar UV-B radiation, which is intensifying worldwide. Dr. 

 Patrick Neale and his colleagues showed that UV-B absorb- 

 ing pigments in a common form of Chesapeake Bay algae 

 (dinoflagellates) protect against damage to photosynthesis. 

 This finding resolved a controversy about whether such 

 "sunscreens" really protect single-celled organisms only a 

 few thousandths of an inch in diameter. New SERC studies 

 in the Chesapeake Bay, Gulf of Mexico and the Southern 

 Ocean near Antarctica investigate effects of UV-B on the 

 growth of aquatic bacteria. Such effects may influence global 

 nutrient cycles. 



Another SERC program examines the effects of global in- 

 creases in atmospheric carbon dioxide. Dr. Bert Drake led 

 the ongoing, long-term study of a scrub-oak forest at the 

 Merritt Island Wildlife Refuge on Cape Canaveral, Florida. 

 The research showed that the effects of the severe drought 

 during 1998 were to some extent mitigated by incteasing at- 

 mospheric carbon dioxide. Scrub oak exposed to a level of 

 carbon dioxide that we expect to occur during the next cen- 

 tury used water more efficiently and therefore continued to 

 grow even at the height of the drought. In contrast, oaks ex- 

 posed to normal ambient carbon dioxide were so severely 

 stressed that their abilities to assimilate atmospheric carbon 

 dioxide and to grow were severely repressed. These results 

 confirm that at least some effects of rising atmospheric car- 

 bon dioxide have a positive effect on native species plant 

 species. 



SERC researchers directed by Dr. Jess Parker completed a 

 1 o-year study of development in local forests using an exten- 

 sive network of plots in forests of different ages. The results 

 show how forests change over time in structure, growth, and 

 diversity. The way a patch of vegetation changes when left 

 alone is an important component of how entire landscapes 

 change — the other dominant component is change caused by 

 external events, such as the disturbance by human modifica- 

 tions, by natural disasrers, and by pests. One SERC forest 

 was mapped in parricularly great detail. A large cadre of vol- 

 unteers helped map the large, canopy trees in a 43-hectare 

 (107-acre) area around SERC's forest research tower. The de- 

 tailed study provides insight on the main factors controlling 

 how trees are distributed within the main type of forest in 

 the SERC vicinity: the tolerance of moisture and shade and 

 the effects of past human modifications to the land. 



Parker has also extended his foresr studies ro include a 

 broad survey of light transmittance patterns measured in 

 tropical, subtropical, western conifer, and eastern deciduous 

 forest canopies. This survey is showing the imporrance of de- 

 velopmental stage, forest type, and disturbance on how light 

 is distributed in forests, and will likely have some implica- 

 tions for forest management. 



Future studies of forests will be aided by SERC's recent 

 development of a portable laser system for sensing forest 

 canopy structure. The prototype system has been deployed 

 both from the ground, carried by a person on a backpack, 

 and from the air, supported by a helicopter. Such a system 



