Carbon stable isotope record in the coral species Siderastrea stellata: A link to the Suess Effect in the tropical South Atlantic Ocean

Abstract

Coral skeletons are natural archives whose geochemical signatures provide insights into the tropical ocean history beyond the instrumental record. Carbon stable isotopes from coral skeletons (δ 13 Ccoral) have been used as a proxy for multiple variables on a seasonal basis. Long-term changes in coral δ 13 C relate to the changing isotopic composition of the dissolved inorganic carbon (δ 13 CDIC). δ 13 CDIC in turn reflects changes in the δ 13 C of atmospheric CO2, which in the modern Earth system is governed primarily by anthropogenic injection of CO2 into the atmospherea process known as the Suess Effect.Here we report three δ 13 C coral-based records of Siderastrea stellata from the tropical South Atlantic. U-series dating for the colonies 12SFB-1, 13SS-1 and 13SS-2 suggests these corals lived 13, 57 and 65 years, respectively. Short-term δ 13 C variations in their skeletal aragonite are dominated by inter-annual variation. All three δ 13 C records additionally exhibit an overall decreasing trend, with a depletion of about −0.0243 ± 0.0057 ‰.yr −1 (12SFB-1), −0.0208 ± 0.0007 ‰.yr −1 (13SS-1) and −0.0214 ± 0.0013 ‰.yr −1 (13SS-2). These rates of the coral records from Rocas Atoll are similar to the reported trend for the δ 13 C of atmospheric CO2 over the years 1960-1990 (−0.023 to −0.029 ‰.yr −1 ), and to the estimated decreasing rates of global δ 13 CDIC.Our findings suggest that multiple δ 13 C coral-based records are required for confidently identifying local changes in the δ 13 CDIC of the ocean. This information, in turn, can be used to infer changes in the δ 13 C of the atmospheric CO2 composition and provide valuable information about recent changes on the carbon biogeochemical cycle during the Anthropocene epoch.

Decadal changes in blood δ 13 C values, at-sea distribution, and weaning mass of southern elephant seals from Kerguelen Islands

“…Oceanic dissolved inorganic carbon (DIC) δ 13 C relies on atmospheric CO 2 composition [58] and may be influenced by the Suess effect [39], whose magnitude varies with latitude and ocean basins [59]. Previous studies investigating metabolically inert tissues in Arctic marine mammals and seabirds, and in coral species in tropical ecosystems imputed a decrease in δ 13 C values to the Suess effect [37,60] at times combined with changes in primary productivity [35,38,39,61]. However, the Southern Ocean's Suess effect accounts for only approximately −0.01‰ per decade [59,62], whereas our dataset showed a tenfold greater decrease in blood δ 13 C values (i.e.…”

Mid to late 20th century freshening of the western tropical South Atlantic triggered by southward migration of the Intertropical Convergence Zone

“…In contrast, only a few shallow-water coral records have been generated from corals sampled in the western tropical South Atlantic (Table 1) (Evangelista et al 2007(Evangelista et al , 2018Mayal et al 2009;Pereira et al 2016Pereira et al , 2017Pereira et al , 2018. These studies exclusively explored two sites (i.e., Rocas atoll and Abrolhos) from all available Brazilian reef systems (Leão et al 2016).…”

Scientific diving in Brazil: history, present and perspectives

“…First used in 2003 (Santedicola, 2008), underwater coring of corals and reefs has been conduct to obtain samples to understand the mechanism of coral calcification (Oliveira et al, 2008;Kikuchi et al, 2013), paleoceanographic studies (Santedicola, 2008;Kikuchi et al, 2013;Pereira et al, 2015Pereira et al, , 2018, sea level reconstruction, and reef evolution (Bastos et al, 2018). The techniques used in these studies are underwater navigation, operating percussion, and pneumatic (Santedicola, 2008;Kikuchi et al, 2013;Pereira et al, 2015Pereira et al, , 2018 or hydraulic drilling accessories and equipment.…”

“…First used in 2003 (Santedicola, 2008), underwater coring of corals and reefs has been conduct to obtain samples to understand the mechanism of coral calcification (Oliveira et al, 2008;Kikuchi et al, 2013), paleoceanographic studies (Santedicola, 2008;Kikuchi et al, 2013;Pereira et al, 2015Pereira et al, , 2018, sea level reconstruction, and reef evolution (Bastos et al, 2018). The techniques used in these studies are underwater navigation, operating percussion, and pneumatic (Santedicola, 2008;Kikuchi et al, 2013;Pereira et al, 2015Pereira et al, , 2018 or hydraulic drilling accessories and equipment. In situ studies on coral calcification were conducted by coral skeleton staining (Kikuchi et al, 2013), while studies on reef sedimentation rates (Dutra et al, 2006;Segal and Castro, 2011) required choosing suitable sites to install sediment traps and returning periodically to replace the devices.…”