Integrating global chlorophyll data from 1890 to 2010

Abstract

Understanding large-scale phytoplankton dynamics requires accurate, multi-decadal measurements of abundance and distribution. Since 1890, marine phytoplankton abundance has been assessed using a diverse range of sensors and observational platforms, and inter-calibrating these data have been challenging. Consequently, syntheses of historical phytoplankton data have been rarely attempted, and the need for accurate, long-term assessments of phytoplankton abundance and distribution is commonly acknowledged. Here, we derive quantitative indices of phytoplankton abundance from measurements of upper ocean transparency and color-calibrated with direct measurements of surface chlorophyll. The strong correlation and linear scaling of the predicted data enabled the construction of a comprehensive, globally intercalibrated chlorophyll time series from 1890 to 2010. The calibrated chlorophyll data reproduced the well-established spatial features of phytoplankton surface biomass and were strongly correlated with chlorophyll concentration derived from two independent remote sensing platforms discontinuously available since 1978. These results suggest that with careful statistical treatment it is possible to generate a globally integrated chlorophyll time series extending 120 years into the past. This database, which is available in the web appendices of this paper, may enable new insights in the areas of climate science, biogeochemical cycling, and marine ecosystem structure and functioning over the past century.

Temporal changes in total and size-fractioned chlorophyll-a in surface waters of three provinces in the Atlantic Ocean (September to November) between 2003 and 2010

“…Boyce et al (2014) report significant declines in TCHLa in the North West Atlantic, Eastern Atlantic and South Atlantic over the past century, using a dataset of merged Secchi disc observations, Forel-Ule (FU) colour data, and TCHLa data (Boyce et al, 2010(Boyce et al, , 2012. Boyce et al (2014) also report a significant increase in TCHLa in the North East Atlantic, in agreement with trends presented by Raitsos et al (2005Raitsos et al ( , 2014 and McQuatters-Gollop et al (2011), derived using the Continuous Plankton Recorder (CPR) Phytoplankton Colour Index (PCI).…”

Changing recruitment capacity in global fish stocks

“…Historical SST data were extracted from the Simple Ocean Data Assimilation (33), and CHL data were taken from the in situ database provided in ref. 8. The trend model for CHL contained a seasonal term due to unequal seasonal sampling, whereas mean annual temperatures were extracted for SST.…”

“…However, the net effect of these changes on global fish stock productivity is not clearly understood. In particular, documented environmental changes (4,8,9) and the long-term consequences of overfishing (10, 11) all impose relevant but poorly constrained effects. Here we help address this issue by evaluating the evidence for empirical trends in the relation between the size of the reproductively mature population (or "spawning stock") and the annual production of juvenile offspring ("recruits") using a recently synthesized global database of stock-recruit time series (12).…”

Meridional patterns of inorganic nutrient limitation and co-limitation of bacterial growth in the Atlantic Ocean

“…Most models predict both a decrease in the deposition of high N:P Saharan dust (Mahowald and Luo, 2003), currently a major source of nutrients to the subtropical North Atlantic (Baker et al, 2003(Baker et al, , 2006, and an increase in ocean stratification and a concomitant reduction in nutrient supply from deep water (Behrenfeld et al, 2006;Boyce et al, 2012;IPCC, 2013). Reduced dust and deep water inputs of inorganic nutrients to surface waters will further reduce primary production and nitrogen fixation.…”