Abstract. We present estimates of total nitrogen and total phosphorus fluxes in rivers to the North Atlantic Ocean from 14 regions in North America, South America, Europe, and Africa which collectively comprise the drainage basins to the North Atlantic. The Amazon basin dominates the overall phosphorus flux and has the highest phosphorus flux per area. The total nitrogen flux from the Amazon is also lar¥e, contributing 3.3 Tg yr

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We estimated nitrogen fixation from the increase in total nitrogen (N 2 gas excluded) in the upper 20 m during the summer biomass increase of heterocystous filamentous cyanobacteria at the off-shore Landsort Deep station (BY31, 5 yr) and at 10 more stations in all major basins of the Baltic Sea proper. Estimated fixation rates were 2.3-5.9 mmol N m Ϫ2 d Ϫ1, within the range of reported direct measurements. Estimated total fixation in the Baltic Sea proper, 180-430 Gg N yr Ϫ1 taking nitrogen settling loss and atmospheric deposition into account, was sufficient to sustain 30-90% of the June-August pelagic net community production. Filamentous cyanobacteria (mostly Aphanizomenon sp.) had low C : N and C : P ratios in spring 1998, indicating internal storage of both N and P. From early June, when their biomass growth started, ratios rose gradually to the biomass peak in August and early September, when the C : N ratio (6.5 mol/mol) was close to the Redfield ratio, but the C : P ratio reached 420, almost four times Redfield. The C : N ratio of the peak biomass was 1.5 times that in spring, and the C : P ratio was 13 times higher. The high C : P ratio indicates a smaller P demand by filamentous diazotrophs than expected from Redfield ratios. Only a few percent of the P mineralized daily is needed for filamentous cyanobacterial growth in summer. Filamentous cyanobacteria incorporated 16-41 mmol N m Ϫ2 into biomass (C : N ϭ 6.2) at BY31 in summer 1998. This was less than the estimated nitrogen fixation, suggesting fixed N leaks from growing diazotrophs.

Time series of environmental measurements are essential for detecting, measuring and understanding changes in the Earth system and its biological communities. Observational series have accumulated over the past 2-5 decades from measurements across the world's estuaries, bays, lagoons, inland seas and shelf waters influenced by runoff. We synthesize information contained in these time series to develop a global view of changes occurring in marine systems influenced by connectivity to land. Our review is organized around four themes: (i) human activities as drivers of change; (ii) variability of the climate system as a driver of change; (iii) successes, disappointments and challenges of managing change at the sea-land interface; and (iv) discoveries made from observations over time. Multidecadal time series reveal that many of the world's estuarine-coastal ecosystems are in a continuing state of change, and the pace of change is faster than we could have imagined a decade ago. Some have been transformed into novel ecosystems with habitats, biogeochemistry and biological communities outside the natural range of variability. Change takes many forms including linear and nonlinear trends, abrupt state changes and oscillations. The challenge of managing change is daunting in the coastal zone where diverse human pressures are concentrated and intersect with different responses to climate variability over land and over ocean basins. The pace of change in estuarine-coastal ecosystems will likely accelerate as the human population and economies continue to grow and as global climate change accelerates. Wise stewardship of the resources upon which we depend is critically dependent upon a continuing flow of information from observations to measure, understand and anticipate future changes along the world's coastlines.

Abstract-Massive summer blooms of nitrogen-fixing cyanobacteria have been documented in the Baltic Sea since the 19th century, but are reported to have increased in frequency, biomass, and duration in recent decades-presumably in response to the well-documented anthropogenic eutrophication of the Baltic. Here, we present an 8,000-yr record of fossil cyanobacterial pigments, diatom microfossil assemblages, and ␦ 15