Calcareous nannofossil assemblages of Ocean Anoxic Event 2 in ODP Sites 207-1258 and 207-1260

The calcareous nannofossils of the Cenomanian/Turonian boundary interval of Sites 1258 and 1260 (Ocean Drilling Program Leg 207) have been studied in order to understand the depositional environment during Oceanic Anoxic Event 2 (OAE2) in the equatorial Atlantic. Nannofossil assemblages show a significant change in relative abundances during the positive d13Corg excursion interval. The strong increase of the high productivity indicator Zeugrhabdotus erectus and the simultaneous decrease of the oligotrophic taxa Watznaueria barnesiae and Watznaueria fossacincta are indicative of enhanced fertility. The decrease of Eprolithus floralis may be attributed to the surface-water temperature increase during OAE2, which is, however, not very significant (~2-3 °C), as suggested by published TEX86 data. It seems more likely that the decrease of E. floralis during OAE2 was evoked by the breakdown of water-column stratification, indicating it as a deep-dwelling species, which prefers stratified waters with a deep nutricline. Prediscosphaera spp. and Retecapsa ficula, which show a significant increase in relative abundances during OAE2, seem to prefer eutrophic environments, while Amphizygus brooksii and Zeugrhabdotus noeliae lower surface-water fertility. Gartnerago segmentatum, Broinsonia spp., Watznaueria biporta, and Seribiscutum gaultensis decrease in abundances during OAE2. It is not clear if they preferred an oligotrophic environment, cooler surface-waters, or if they were inhabitants of the lower photic zone. Published geochemical data suggest that enhanced fertility and higher temperatures during OAE2 may have been caused by submarine volcanic activity through the release of biolimiting micronutrients into the ocean and carbon dioxide into the atmosphere. The breakdown of water-column stratification may have increased further nutrient availability.

Diurnal and seasonal measurements of seawater chemistry, temperature and PAR in Hurricane Hole, U.S. Virgin Islands - 2010-2012

Risk analyses indicate that more than 90% of the world's reefs will be threatened by climate change and local anthropogenic impacts by the year 2030 under "business-as-usual" climate scenarios. Increasing temperatures and solar radiation cause coral bleaching that has resulted in extensive coral mortality. Increasing carbon dioxide reduces seawater pH, slows coral growth, and may cause loss of reef structure. Management strategies include establishment of marine protected areas with environmental conditions that promote reef resiliency. However, few resilient reefs have been identified, and resiliency factors are poorly defined. Here we characterize the first natural, non-reef coral refuge from thermal stress and ocean acidification and identify resiliency factors for mangrove-coral habitats. We measured diurnal and seasonal variations in temperature, salinity, photosynthetically active radiation (PAR), and seawater chemistry; characterized substrate parameters; and examined water circulation patterns in mangrove communities where scleractinian corals are growing attached to and under mangrove prop roots in Hurricane Hole, St. John, US Virgin Islands. Additionally, we inventoried the coral species and quantified incidences of coral bleaching, mortality, and recovery for two major reef-building corals, Colpophyllia natans and Diploria labyrinthiformis, growing in mangrove-shaded and exposed (unshaded) areas. Over 30 species of scleractinian corals were growing in association with mangroves. Corals were thriving in low-light (more than 70% attenuation of incident PAR) from mangrove shading and at higher temperatures than nearby reef tract corals. A higher percentage of C. natans colonies were living shaded by mangroves, and no shaded colonies were bleached. Fewer D. labyrinthiformis colonies were shaded by mangroves, however more unshaded colonies were bleached. A combination of substrate and habitat heterogeneity, proximity of different habitat types, hydrographic conditions, and biological influences on seawater chemistry generate chemical conditions that buffer against ocean acidification. This previously undocumented refuge for corals provides evidence for adaptation of coastal organisms and ecosystem transition due to recent climate change. Identifying and protecting other natural, non-reef coral refuges is critical for sustaining corals and other reef species into the future.

Fig. S1. Loci of possible event locations based on differential ts - tp arrival times at the single functioning geophone

Geological storage of CO2 that has been captured at large, point source emitters represents a key potential method for reduction of anthropogenic greenhouse gas emissions. However, this technology will only be viable if it can be guaranteed that injected CO2 will remain trapped in the subsurface for thousands of years or more. A signi?cant issue for storage security is the geomechanical response of the reservoir. Concerns have been raised that geomechanical deformation induced by CO2 injection will create or reactivate fracture networks in the sealing caprocks, providing a pathway for CO2 leakage. In this paper, we examine three large-scale sites where CO2 is injected at rates of ab. 1 megatonne/y or more: Sleipner, Weyburn, and In Salah. We compare and contrast the observed geomechanical behavior of each site, with particular focus on the risks to storage security posed by geomechanical deformation. At Sleipner, the large, high-permeability storage aquifer has experienced little pore pressure increase over 15 y of injection, implying little possibility of geomechanical deformation. At Weyburn, 45 y of oil production has depleted pore pressures before increases associated with CO2 injection. The long history of the ?eld has led to complicated, sometimes nonintuitive geomechanical deformation. At In Salah, injection into the water leg of a gas reservoir has increased pore pressures, leading to uplift and substantial microseismic activity. The differences in the geomechanical responses of these sites emphasize the need for systematic geomechanical appraisal before injection in any potential storage site.

Seawater carbonate chemistry and physiological responses of three temperate coralline algae in a laboratory experiment

Coralline algae are major calcifiers of significant ecological importance in marine habitats but are among the most sensitive calcifying organisms to ocean acidification. The elevated pCO2 effects were examined in three coralline algal species living in contrasting habitats from intertidal to subtidal zones on the north-western coast of Brittany, France: (i) Corallina elongata, a branched alga found in tidal rock pools, (ii) Lithophyllum incrustans, a crustose coralline alga from the low intertidal zone, and (iii) Lithothamnion corallioides (maerl), a free-living form inhabiting the subtidal zone. Metabolic rates were assessed on specimens grown for one month at varying pCO2: 380 (current pCO2), 550, 750 and 1000 µatm (elevated pCO2). There was no pCO2 effect on gross production in C. elongata and L. incrustans but L. incrustans respiration strongly increased with elevated pCO2. L. corallioides gross production slightly increased at 1000 µatm, while respiration remained unaffected. Calcification rates decreased with pCO2 in L. incrustans (both in the light and dark) and L. corallioides (only in the light), while C. elongata calcification was unaffected. This was consistent with the lower skeletal mMg/Ca ratio of C. elongata (0.17) relative to the two other species (0.20). L. incrustans had a higher occurrence of bleaching that increased with increasing pCO2. pCO2 could indirectly impact this coralline species physiology making them more sensitive to other stresses such as diseases or pathogens. These results underlined that the physiological response of coralline algae to near-future ocean acidification is species-specific and that species experiencing naturally strong pH variations were not necessarily more resistant to elevated pCO2 than species from more stable environment.

Palynology and sea surface temperature reconstruction for the mid-Cretaceous Oceanic Anoxic Event 2 at ODP Hole 210-1276A

The mid-Cretaceous is thought to be a greenhouse world with significantly higher atmospheric pCO2 and sea-surface temperatures as well as a much flatter latitudinal thermal gradient compared to the present. This time interval was punctuated by the Cenomanian/Turonian Oceanic Anoxic Event (OAE-2, ~ 93.5 Myr ago), an episode of global, massive organic carbon burial that likely resulted in a large and abrupt pCO2 decline. However, the climatic consequences of this pCO2 drop are yet poorly constrained. We determined the first, high-resolution sea-surface temperature (SST) record across OAE-2 from a deep-marine sedimentary sequence at Ocean Drilling Program (ODP) Site 1276 in the mid-latitudinal Newfoundland Basin, NW Atlantic. By employing the organic palaeothermometer TEX86, we found that SSTs across the OAE-2 interval were extremely high, but were punctuated by a remarkably large cooling (5-11 °C), which is synchronous with the 2.5-5.5 °C cooling in SST records from equatorial Atlantic sites, and the "Plenus Cold Event". Because this global cooling event is concurrent with increased organic carbon burial, it likely acted in response to the associated pCO2 drop. Our findings imply a substantial increase in the latitudinal SST gradient in the proto-North Atlantic during this period of global cooling and reduced atmospheric pCO2, suggesting a strong coupling between pCO2 and latitudinal thermal gradients under greenhouse climate conditions.