ALBERT

Description: The end-Cretaceous bolide impact triggered the devastation of marine ecosystems. However, the specific kill mechanism(s) are still debated, and how primary production subsequently recovered remains elusive. We used marine plankton microfossils and eco-evolutionary modeling to determine strategies for survival and recovery, finding that widespread phagotrophy (prey ingestion) was fundamental to plankton surviving the impact and also for the subsequent reestablishment of primary production. Ecological selectivity points to extreme post-impact light inhibition as the principal kill mechanism, with the marine food chain temporarily reset to a bacteria-dominated state. Subsequently, in a sunlit ocean inhabited by only rare survivor grazers but abundant small prey, it was mixotrophic nutrition (autotrophy and heterotrophy) and increasing cell sizes that enabled the eventual reestablishment of marine food webs some 2 million years later.

Description: This study presents the physical oceanography analysis in the NE Aegean Sea. Stations were located along a north-south transect in the area receiving the inflowing surface Black Sea Water (BSW) over the deeper Levantine Water (LW) layer. 6 different sample depths were sampled.

Description: This study presents the species composition of living coccolithophore communities in the NE Aegean Sea. 72 water samples from 4 different sampling stations were investigated. Stations were located along a north-south transect in the area receiving the inflowing surface Black Sea Water (BSW) over the deeper Levantine Water (LW) layer. 6 different sample depths were sampled. Coccolithophores in the area were diverse and a total of 95 species over 3 sampling periods were recognized using Scanning Electron Microscope (SEM) techniques.

Description: Underway temperature and salinity data was collected along the cruise track with two autonomous thermosalinograph (TSG) systems, each consisting of a SBE21 TSG together with a SBE38 Thermometer. Both systems worked independent from each other throughout the cruise. While temperature is taken at the water inlet in about 5 m depth, salinity is estimated within the interior TSG from conductivity and interior temperature. No correction against independent data was performed for temperature and salinity. Finally, TSG1 was chosen for publication. For details to all processing steps see Data Processing Report.

Description: The Paleocene-Eocene Thermal Maximum (PETM) was an abrupt and extreme warming event associated with rapid input of light carbon into the ocean-atmosphere system. The carbon cycle perturbations during the PETM caused significant changes to marine plankton, including extinction of some benthic foraminifers and the appearance of malformed calcareous nannoplankton, possibly related to ocean acidification during the event. The PETM is now considered a potential analog for the effects of anthropogenic climate change due to its rapid onset; thus, study of PETM records offers an opportunity to better understand the potential effects of rapid climate change on marine phytoplankton communities. Here we present calcareous nannofossil assemblage data across a newly recovered PETM section from International Ocean Discovery Program (IODP) Site U1580, drilled on the central Agulhas Plateau during IODP Expedition 392 in early 2022. Present water depth at this site is 2560 m and it sits at 40° 47.15’S, although the site has moved progressively northward since the Agulhas Plateau formed in the mid-Cretaceous, when the site was located about 20° further south. The PETM interval was identified during the expedition by a change in sediment color, increase in magnetic susceptibility, and calcareous nannofossil assemblages. Low-resolution bulk 13C measurements conducted following the expedition confirm a negative isotope excursion and decrease in calcium carbonate content across the interval. The shipboard age model based on nannofossil and planktonic foraminifer biostratigraphy, together with magnetostratigraphy, suggests relatively high sedimentation rates (~2.5 cm/kyr). Nannofossil assemblages are quite well preserved, with PETM-specific taxa present including Rhomboaster calcitrapa, Rhomboaster cuspis, Rhomboaster bramlettei, Discoaster araneus, and Discoaster acutus. Initial qualitative analyses indicate Zygrhablithus bijugatus is particularly abundant within the PETM interval, whereas Fasciculithus spp. decrease in abundance. Discoaster spp. are also more abundant in the earliest Eocene, as are Neochiastozygus spp. Neococcolithes spp., and Ellipsolithus bollii. The position of this new site between Maud Rise Site 690 and Walvis Ridge Sites 1262, 1263, and 1265 should shed new light on this event in the southern mid-latitudes.

Description: International Ocean Discovery Program (IODP) Expedition 392 cored three sites on the Agulhas Plateau and one site in the Transkei Basin to address questions regarding the origin and timing of emplacement of Agulhas Plateau, as well as examine Southern Ocean climate history and opening of oceanic gateways from the Cretaceous through the Paleogene. Age models for the sites rely primarily on calcareous nannofossils and magnetostratigraphy, with dinoflagellates providing key events for some intervals, and additional contributions from planktonic foraminifers and diatoms. Site U1579, located in a basin on southern the central Agulhas Plateau, records a nearly continuous section dated to the Santonian to earliest Miocene. Dinoflagellates provide age control for the zeolitic sandstone and siltstone with glauconite at the base of the cored section. Above this, nannofossils are common to abundant and moderately preserved in upper Santonian to Maastrichtian calcareous chalks and the assemblages show Southern Ocean affinities. Paleogene nannofossils are abundant and moderately to well preserved. Sedimentation rates were lowest in the Eocene, which includes either condensed intervals or hiatuses. Nannofossils are well preserved in the Oligocene and assemblages consist of primarily mid-latitude species with occasional incursions of cold-water taxa. Site U1580 is also located on the southern Agulhas Plateau adjacent to a basement high. This site records several unconformities, and the lowermost part of the cored interval is interspersed with basalt layers interpreted as sills. The oldest sediment is likely uppermost Cenomanian in age. Overlying the shallowest basalt is Coniacian–Santonian silt- and sandstone with varying proportions of zeolites, glauconite, and carbonate. Sedimentation rates were very high (~10 cm/ky) during this time. Much of the early Campanian and mid-Maastrichtian is missing at this site. Paleocene nannofossils are moderately well preserved and suggest a continuous section with sedimentation rates of 1.5 cm/ky. Sedimentation rates increased in the late Paleocene to early Eocene, and nannofossils are quite well preserved through the Paleocene-Eocene Thermal Maximum and in the lower Eocene chalk/ooze. Site U1581 in the Transkei Basin includes a thick section of upper Campanian to Maastrichtian mudstone with occasional sandstone beds. Nannofossil are sparse but very well preserved through much of this interval, although preservation decreases with depth, concomitant with increasing siderite. The Cretaceous assemblages include both Southern Ocean and mid-latitude taxa. Reworking is common throughout the Cenozoic and this interval is also interspersed with hiatuses, especially in the Eocene and Miocene. Sedimentation appears to be more continuous from the latest Miocene to present, with sedimentation rates of ~2.8 cm/ky. Site U1582, cored on the northern Agulhas Plateau, includes only ~40 m of ooze and siliciclastic sediments overlying basement. Manganese nodules are common and the section is highly condensed, with at least 70 Myr represented. Future work will refine the age models for each site to provide a framework for the paleoclimatic and paleoceanographic studies planned by the expedition science party members.