launch — from planning observations, to analyzing resulcs, 

 to archiving data for the world scientific community. 



SI Secretary I. Michael Heyman and Dr. Yuan-Tseh Lee, Presi- 

 dent of the Academia Sinica of Taiwan, signed a partner- 

 ship agreement in Honolulu on June 17, 1996, to 

 collaborate on, and to provide two antennas for, the Submil- 

 limeter Array project now under construction by SAO on 

 Mauna Kea, Hawaii. 



In August 1996, the Annenberg/CPB Math and Science 



Project awarded SAO $i.3-million to create, in cooperation 

 with the Massachusetts Corporation for Educational 

 Telecommunications (MCET), a satellite television service 

 and companion World Wide Web site to provide program- 

 ming for teachers, schools, and communities, which will 

 draw on the Annenberg/CPB Project archival materials. 



Smithsonian Environmental 

 Research Center 



David L. Correll. Director 



The Smithsonian Environmental Research Center (SERC) 

 maintained its research and education programs with a focus 

 on the interactions of plants and animals with their environ- 

 ment. Staff moved into a new office building and the Old 

 Dominion wing of the Charles Mathias Laboratory Building 

 was demolished. 



This year SERC scientists published 29 research papers as a 

 result of a series of ongoing atmospheric, terrestrial, and 

 aquatic studies. In December, 1994 total ozone in the atmos- 

 phere over Mauna Loa, Hawaii dropped to the lowest levels 

 observed in over 30 years. These low ozone levels resulted in 

 the penetration of much higher levels of ultraviolet radiation 

 from the sun, especially in the range of 295 to 305 nm, which 

 is much more biologically damaging. 



The concentrations of carbon dioxide in the atmosphere 

 have been increasing due to human activities such as combus- 

 tion of fossil fuels. SERC scientists have been exposing plant 

 communities continuously to concentrations of carbon 

 dioxide expected to occur in about 50 years. An oak-palmetto 

 scrub ecosystem in Florida responded to this treatment by 

 producing almost double the amount of fine roots found in 

 controls. These roots make the plants more efficient at com- 

 petition for nutrients and water, and are a mechanism for in- 

 creased storage of organic carbon below ground. 



Through human activities such as the production of 

 nitrogen fertilizers, the rate of nitrogen fixation from the at- 

 mosphere has roughly doubled in the last few decades. The in- 

 creased rates of fixed nitrogen application to the landscape 

 have lead to greatly increased leaching of nitrate into 

 groundwater and surface waters and consequent adverse im- 

 pacts on these systems. Approximately one-third of the 



anthropogenic nitrogen inputs are lost in streams and rivers, 

 primarily as nitrate. 



Along the Atlantic Coast of Central America lies the 

 second largest coral barrier reef in the World. Many of the 

 Cays in this reef system are dominated by mangrove forests. 

 SERC scientists experimentally fertilized plots of the red 

 mangrove with phosphorus, nitrogen, or both elements. Phos- 

 phorus treatments resulted in greatly increased overall 

 growth, leaf area, leaf number, branching, and shoot length, 

 while nitrogen treatments had little effect. The phosphorus 

 treated plants also attracted more herbivorous insects. These 

 resulcs were surprising since most marine systems are 

 nitrogen limited. 



Mud crabs and the parasitic barnacle Loxothyltuus panopaei 

 are common in the Rhode River near the SERC laboratory. As 

 the barnacle develops in a crab it castrates the host and 

 prevents its growth. When immature crabs were exposed to 

 barnacle larvae, the survival rate of the crabs to a young adult 

 stage was lowered from 50% to 6%. It is believed that these 

 parasites have a significant impact on the populacions of crabs 

 in Chesapeake Bay. In another case the parasitism of one 

 dinoflagellate on other species of dinoflagellates was studied. 

 Dinoflagellates are microscopic phycoplankcon which com- 

 monly form red cides in Chesapeake Bay. Infeccion levels in 

 field populacions usually ranged from one to 6.5%, but oc- 

 casional epidemics of 20 to 80% infection were observed. 

 Thus, parasites are important in Chesapeake Bay at both the 

 microscopic and macroscopic levels. 



Sea food production and harvesting have impacts on the 

 ecology of the area. SERC scientists found that hydraulic 

 dredging for soft-shell clams in Chesapeake Bay produces 

 higher levels of suspended sediments in shallow water areas, 

 which attenuates sunlight and adversely impacts populations 

 of submersed higher aquacic plants. Most of the clam boats 

 operate in less than two meters of water and the average area 

 of the suspended sediment plume per boat was eight hectares. 

 The effects of oyster manculrure on submersed aquatic vegeta- 

 tion were investigated in an estuary in Oregon. Several cypes 

 of oyster culture were found to decrease the abundance of the 

 aquatic plants by 75%, apparently due to higher sediment 

 deposition and direct physical disturbance. 



An optical water quality model, developed by SERC scien- 

 tists in the Rhode River, was applied to the Indian River 

 Lagoon in Florida to predict limitations of water quality on 

 seagrass populations. A major factor was inputs of humic acid- 

 containing waters from local drainage canals. The model ade- 

 quately predicted light attenuation and agreed with the 

 observed losses in area of seagrass beds. 



Male blue crabs guard theit mates before and after mating, 

 which occurs after they shed their hard exoskeleton. Studies 

 on Chesapeake Bay found that large males were paired with 

 mates more often, spent more time competing for mates, were 

 more successful at aggressive interactions for females, passed 

 more sperm to each female, and mated with larger, more 

 fecund females. Male guarding durations were long enough to 



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