GEOPHYSIOLOGICAL COUPLING OF MARINE AND TERRESTRIAL ECOSYSTEMS

Areas of high ocean productivity tend to be coastal, suggesting that o cean and terrestrial ecosystems may be closely coupled. A geophysiolog ical model proposes that coastal marine and peatland ecosystems are ti ghtly coupled primarily via atmospheric pathways of sulfur from oceans to peatlands, which are mainly sulfur limited and via the riverine an d groundwater transport of soluble organic iron from peatlands to ocea ns, which are mainly iron limited. Findings from the literature, along with precipitation pH data from southeast Alaska, are presented in su pport of the proposed pathways. Nutrient limitation studies show incre ases in primary productivity of marine and peatland ecosystems associa ted with additions of iron and sulfur, respectively. Mechanisms of nut rient transport commonly invoked to explain ocean productivity are not sufficient in accounting for regional and global patterns of chloroph yll concentration. Regional and global distributions of peatland cover shows remarkable correspondance with chlorophyll concentration data, consistent with model predictions.