Saturday, July 30, 2011

New paper shows global warming has increased phytoplankton and fish

From the NIPCC weekly update 8/2/11:

Reference: Chavez, F.P., Messie, M. and Pennington, J.T. 2011. Marine primary production in relation to climate variability and change. Annual Review of Marine Science 3: 227-260.

Writing in the Annual Review of Marine Science, Chavez et al. (2011) state that "marine photosynthetic plankton are responsible for approximately 50 petagrams (1015) of carbon per year of net primary production, an amount equivalent to that on land," and they say that "this primary production supports essentially all life in the oceans and profoundly affects global biogeochemical cycles and climate."

With this brief background, Chavez et al. go on to review the concepts and methods used to estimate ocean primary production (PP), after which they use the modern global instrumental record of sea surface temperature (SST) to analyze the principal modes of inter-annual to multi-decadal climate and ocean variability. Spatiotemporal patterns derived from in situ and satellite time-series of PP are then compared with the known time-series of climate and ocean variability in a search for the processes responsible for the observed patterns in PP, after which paleoclimate studies are introduced in an attempt to broaden the temporal context and "lead into speculation regarding century-scale variability."

Based on the first part of their analysis, the three researchers -- all from the Monterey Bay Aquarium Research Institute of Moss Landing, California (USA) -- write that "general conclusions from the satellite and in situ time-series presented here are that PP [photosynthetic plankton or phytoplankton] is increasing globally," and they note that global marine PP appears to have risen over the past several decades in association with multi-decadal variations in climate. In addition, they indicate that data from Continuous Plankton Recorder surveys conducted in the north Atlantic depict "increases in chlorophyll from the 1950s to the present," citing McQuartters-Gollop et al. (2007).

In the second part of their analysis, Chavez et al. (2011) report that ocean sediment cores containing an "undisturbed history of the past" have been analyzed for variations in PP over timescales that include the Little Ice Age (LIA, ~1400-1800; Gutierrez et al., 2009)." And based on reconstructed flux rates of total organic carbon (Sifeddine et al., 2008), diatoms, silica, and fish scales, bones and vertebrae, they determined that during the LIA [Little Ice Age] the ocean off Peru had "low PP, diatoms and fish," but that "at the end of the LIA, this condition changed abruptly to the low subsurface oxygen, eutrophic upwelling ecosystem that today produces more fish than any region of the world's oceans (Chavez et al., 2008)."

Chavez et al. (2011) write that "in coastal environments, PP, diatoms and fish and their associated predators are predicted to decrease and the microbial food web to increase under global warming scenarios," citing Ito et al. (2010). However, they say that, "present-day trends and the sedimentary record seem to indicate that the opposite might occur."

Additional References:

Chavez, F.P., Bertrand, A., Guevara, R., Soler, P. and Csirke, J. 2008. The northern Humboldt Current System: brief history, present status and a view towards the future. Progress in Oceanography 79: 95-105.

Gutierrez, D., Sifeddine, A., Field, D.B., Ortlieb, L. Vargas, G., Chavez, F.P., Velazcol, F., Ferreira, V., Tapia, P., Salvatteci, R., Boucher, H., Morales, M.C., Valdes, J., Reyss, J.-L., Campusano, A., Boussafir, M., Mandeng-Yogo, M., Garcia, M. and Baumgartner, T. 2009. Rapid reorganization in ocean biogeochemistry off Peru towards the end of the Little Ice Age. Biogeosciences 6: 835-848.

Ito, S., Rose, K.A., Miller, A.J., Drinkwater, K., Brander, K., Overland, J.E., Sundby, S., Churchitser, E., Hurrell, J.W. and Yamanaka, Y. 2010. Ocean ecosystem responses to future global change scenarios: a way forward. In: Marange, M., Werner, R., Field, J. and Hofmann, E. (Eds.). Marine Ecosystems and Global Change. Oxford University Press, New York, New York, USA, pp 287-322.

McQuatters-Gollop, A., Raitsos, D.E., Edwards, M., Pradhan, Y., Mee, L.D., Lavender, S.J. and Attrill, M.J. 2007. A long-term chlorophyll data set reveals regime shift in North Sea phytoplankton biomass unconnected to nutrient trends. Limnology and Oceanography 52: 635-648.

Sifeddine, A., Gutierrez, D., Ortlieb, L., Boucher, H., Velazco, F., Field, D.B., Vargas,G., Boussafir, M., Salvatteci, R., Ferreira, V., Garcia, M., Valdes, J., Caquineau, S., Mandeng-Yogo, M., Cetin, F., Solis, J., Soler, P. and Baumgartner, T. 2008. Changes in terrestrial runoff, water mass oxygenation and upwelling productivity recorded in laminated sediments off the Central Peruvian Coast spanning the last centuries. Progress in Oceanography 79: 190-197.

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