Human activities and climate variability drive fast‐paced change across the world's estuarine–coastal ecosystems

Abstract

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.

The sensitivity of estuarine aragonite saturation state and pH to the carbonate chemistry of a freshet-dominated river

“…Estuaries support productive ecosystems (Cloern et al, 2014) and significant human populations (Cloern et al, 2015). Critical trophic links within many of these ecosystems may be negatively impacted by increases in dissolved inorganic carbon (DIC) and reduced pH associated with ocean acidification (Haigh et al, 2015).…”

Changing seasonality of the Baltic Sea

“…Estuarine areas world-wide are experiencing rapid changes due to anthropogenic pressures of both local and global nature (Cloern et al, 2016). The ecosystem of the brackish Baltic Sea has been under anthropogenic stress for many decades (Elmgren, 1989).…”

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“…Los datos empleados corresponden a información histórica no periódica, entre 1968 y 2005 (Bonilla y Okuda, 1971;Bonilla y Benítez, 1972;Palazón-Fernández et al, 1996;Morillo y Salazar, 2002) de: temperatura, salinidad and favors others, enabling the generations of blooms of microalgae and eutrophication (Alonso-Rodríguez et al, 2000;Cloern et al, 2016). In several coastal systems, the limitation by N or O varies seasonally (Jennerjahn et al, 2009;Wan et al, 2011).…”