Primary productivity measurements in the Ross Sea, Antarctica: a regional synthesis

[摘要] Polar systems are undersampled due to the difficulty ofsampling remote and challenging environments; however, these systems arecritical components of global biogeochemical cycles. Measurements on primaryproductivity in specific areas can quantify the input of organic matter tofood webs and so are of critical ecological importance as well. However,long-term measurements using the same methodology are available only for afew polar systems. Primary productivity measurements using 14 C-uptakeincubations from the Ross Sea, Antarctica, are synthesized, along withchlorophyll concentrations at the same depths and locations. A total of 19 independent cruises were completed and 449 stations occupied wheremeasurements of primary productivity (each with seven depths) were completed.The incubations used the same basic simulated in situ methodology for all.Integrated water column productivity for all stations averaged 1.10  ±  1.20 g C m −2  d −1 , and the maximum was 13.1 g C m −2  d −1 .Annual productivity calculated from the means throughout the growing seasonequalled 146 g C m −2  yr −1 . The mean chlorophyll concentration inthe euphotic zone (the 1 % irradiance level) was 2.85  ±  2.68 mg m −3 (maximum observed concentration was 19.1 mg m −3 ). Maximumphotosynthetic rates above the 30 % isolume (normalized to chlorophyll)averaged 0.98  ±  0.71 mg C (mg chl) −1  h −1 , similar to themaximum rate found in photosynthesis–irradiance measurements. Productivitymeasurements are consistent with the temporal patterns of biomass foundpreviously, with biomass and productivity peaking in late December; mixedlayers were at a minimum at this time as well. Estimates of planktoncomposition also suggest that pre-January productivity was largely driven bythe haptophyte Phaeocystis antarctica and summer productivity by diatoms. The data set ( https://doi.org/10.26008/1912/bco-dmo.863815.2 , Smith, 2021) will beuseful for a comparison to other Antarctic regions and provide a basis forrefined bio-optical models of regional primary productivity andbiogeochemical models for the Southern Ocean.

[学科分类] 眼科学