warming will be 25% that of CC>2 within the next 50 years (Dickinson 

 and Cicerone, 1986; Mitchell, 1989). Recent evidence has suggested 

 that much of the methane increase is due to biogenic methane 

 released to the atmosphere. The release is a result of imbalance 

 between production and consumption, and therefore, it is important 

 to understand the global biological sources and sinks of methane. 

 Both the producers and consumers of methane are strictly 

 prokaryotic; methane is produced by the archaebacterial group, the 

 methanogens, and consumed by the eubacterial group, the 

 methanotrophs (Rudd and Taylor, 1980) . Standard techniques for 

 studying the rates of methane production and consumption have 

 always been hampered by the inability to directly assess the 

 populations and their response to environmental changes. This 

 problem is particularly amenable to a molecular approach. Probes 

 are now available or are being developed for both groups, and 

 therefore, it should be possible to combine rate measurements with 

 direct assessment of populations. A series of such studies, 

 carried out in a cross-section of the types of habitats known to be 

 important in methane emission to the atmosphere, could yield a 

 broad understanding of this process. This system has the potential 

 for an early warning indicator, because the response of these two 

 populations to environmental change could be predicted and 

 monitored. 



Assessment of Function in Specific Ecosystems: Coastal/Shelf 

 Ecosystem 



High primary production is common with coastal/shelf 

 ecosystems. In many regions, significant increases in primary 

 production and biomass have occurred in parallel with long-term 

 modification and natural perturbation of the environment. Large- 

 scale changes in grazer communities, notably in dominant fish 

 stocks, have also occurred. In addition, this environment is the 

 site of significant long-term carbon burial into sediments, and 

 strong coupling between both land/sea and sea/atmosphere. These 

 processes within the coastal and shelf ecosystem are of major 

 consequence to global biogeochemical processes. 



A fundamental question is the extent to which environmental 

 perturbations, including long-term increases in nutrients, are 

 progressively altering primary production, causing community 

 reorganization and altered dynamics and energy flow at the primary 



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