ALBERT

Beschreibung: This dataset includes organic carbon measurements on sediment samples collected in Bute Inlet (British Columbia, Canada) in October 2016 (cruise number PGC2016007) and October 2017 (cruise number PGC2017005) aboard the research vessel CCGS Vector. The cruise PGC2016007 took place between 7 October and 17 October 2016 and was led by Gwyn Lintern. The cruise PGC2017005 took place between 19 and 29 October and was led by Cooper Stacey. River samples were taken in the Homathko and Southgate rivers using Niskin bottles in the water column and a grab sampler in the river beds and the river deltas

Beschreibung: This dataset includes organic carbon measurements on sediment samples collected in Bute Inlet (British Columbia, Canada) in October 2016 (cruise number PGC2016007) and October 2017 (cruise number PGC2017005) aboard the research vessel CCGS Vector. The cruise PGC2016007 took place between 7 October and 17 October 2016 and was led by Gwyn Lintern. The cruise PGC2017005 took place between 19 and 29 October and was led by Cooper Stacey. Marine sediment samples were collected in Bute Inlet using a box corer for the sandy samples in the submarine channel and a piston corer for the muddy samples in the overbanks and distal basin.

Beschreibung: A suite of eight glassy rims and six crystalline interiors from pillowed basalts was collected from within the Mid-Atlantic Ridge rift valley between 25°N and 30°N during Trans-Atlantic Geotraverse (TAG) NOAA cruises using the R/V Discoverer. Radiochemical neutron activation analysis has been used to determine Tl, Rb. Cs. Co and Cr. Major element and S analyses of the glasses were determined by electron probe microanalysts of small polished chips of glass.

Beschreibung: A suite of three palagonites from pillowed basalts collected from within the Mid-Atlantic Ridge rift valley between 25°N and 30°N wer analysed along with another suite of two hydrothermally altered basaltic breccias and four hydrothermal manganese crusts collected from the TAG hydrothermal field at 26°N on the Mid-Atlantic Ridge. These specimen were collected during Trans-Atlantic Geotraverse (TAG) NOAA cruises using the R/V Discoverer. Two more hydrogenous ferromanganese crusts wer also analysed. They were collected from the eastern extension of the Atlantis Fracture Zone aboard the R/V Kurchatov in 1975. Radiochemical neutron activation analysis has been used to determine Tl, Rb. Cs. Co and Cr. Iron, Mn, and Mg concentrations in the crystalline samples and Mn crusts have been determined by AAS. K was determined by flame photometry, and S in these samples (as well as five glasses) has been determined with a Leco Automatic Sulfur titrator.

Beschreibung: Panktonic foraminiferal tests of the spinose species Orbulina universa, of the non-spinose Globorotalia tumida-menardii complex, and of a mixed species assemblage (grain size fraction 200-400 µm) were isolated from Sierra Leone Rise core GIK13519-2 and analyzed for free, total, and bound (by difference) amino acids to study the isoleucine epimerization mechanism in fossil foraminiferal tests and to define empirical calibration curves for dating deep-sea sediments over the past 900,000 years. Total isoleucine epimerization curves typically separate into three "linear" segments of decreasing apparents rates with increasing time and exhibit a pronounced „species effect“. The degree of epimerization attained at time is considerably lower in O. universa than in G. tumida-menardii while the mixed species results scatter between the limits delineated by the two monospecific curves. Total allo/iso ratios are closely related to the proportion of free to total isoleucine accumulating in the tests indicating that the rate of hydrolysis of matrix proteins and peptides controls the overall epimerization reaction. The results are consistent with experimental evidenve where upon isoleucine epimerizes at a rapid rate in terminal positions but at slow rates in interior positions as well as in the free state. Notwithstanding free isoleucine exhibits the highest degree of epimerized terminal isoleucine. Species-specific hydrolysis and epimerization rates are maintained until about 50 % of bound isoleucine have been hydrolyzed to the free state corresponding to a total allo/iso ratio of about 0.5. Remaining peptide units appear to be more resistent against hydrolysis and separate species then show the same apparent epimerization rate dominantly controlled by the slow conversion rate in the free state until equilibrium is achieved in Miocene samples under deep-ocean temperature conditions. The degree of epimerization attained at comparable time in separate species will, however, remain different due to different initial rates of hydrolysis.

Beschreibung: Experiments with coral fragments (i.e. nubbins) have shown that net calcification is depressed by elevated PCO2. Evaluating the implications of this finding requires scaling of results from nubbins to colonies, yet the experiments to codify this process have not been carried out. Building from our previous research demonstrating that net calcification of Pocillopora verrucosa (2–13 cm diameter) was unaffected by PCO2 (400 and 1000 µatm) and temperature (26.5 and 29.7°C), we sought generality to this outcome by testing how colony size modulates PCO2 and temperature sensitivity in a branching acroporid. Together, these taxa represent two of the dominant lineages of branching corals on Indo-Pacific coral reefs. Two trials conducted over 2 years tested the hypothesis that the seasonal range in seawater temperature (26.5 and 29.2°C) and a future PCO2 (1062 µatm versus an ambient level of 461 µatm) affect net calcification of an ecologically relevant size range (5–20 cm diameter) of colonies of Acropora hyacinthus. As for P. verrucosa, the effects of temperature and PCO2 on net calcification (mg day−1) of A. verrucosa were not statistically detectable. These results support the generality of a null outcome on net calcification of exposing intact colonies of branching corals to environmental conditions contrasting seasonal variation in temperature and predicted future variation in PCO2. While there is a need to expand beyond an experimental culture relying on coral nubbins as tractable replicates, rigorously responding to this need poses substantial ethical and logistical challenges.

Beschreibung: Coral reefs are threatened by ocean acidification (OA), which depresses net calcification of corals, calcified algae, and coral reef communities. These effects have been quantified for many organisms, but most experiments last weeks-to-months, and do not test for effects on community structure. Here, the effects of OA on back reef communities from Mo'orea, French Polynesia (17.492 S, 149.826 W), were tested from 12 November 2015 to 16 November 2016 in outdoor flumes maintained at mean pCO2 levels of 364 µatm, 564 µatm, 761 µatm, and 1067 µatm. The communities consisted of four corals and two calcified algae, with change in mass (Gnet, a combination of gross accretion and dissolution) and percent cover recorded monthly. For massive Porites and Montipora spp., Gnet differed among treatments, and at 1067 µatm (relative to ambient) was reduced and still positive; for Porolithon onkodes, all of which died, Gnet was negative at high pCO2, revealing dissolution (sample sizes were too small for analysis of Gnet for other taxa). Growth rates (% cover month−1) were unaffected by pCO2 for Montipora spp., P. rus, Pocillopora verrucosa, and Lithophyllum kotschyanum, but were depressed for massive Porites at 564 µatm. Multivariate community structure changed among seasons, and the variation under all elevated pCO2 treatments differed from that recorded at 364 µatm, and was greatest under 564 µatm and 761 µatm pCO2. Temporal variation in multivariate community structure could not be attributed solely to the effects of OA on the chemical and physical properties of seawater. Together, these results suggest that coral reef community structure may be more resilient to OA than suggested by the negative effects of high pCO2 on Gnet of their component organisms.