Beschreibung: Siderophore type chelates were detected in nutrient enriched, incubated seawater collected from different biogeographical regions of the Atlantic Ocean. Seawater was enriched with glucose and ammonium, glycine (as a source of carbon and nitrogen) or chitin and ammonium at different concentrations and was incubated for up to 3-4. days in the dark. Siderophore type chelates were detected using high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP-MS) after complexation with Ga. Samples were subsequently analysed by HPLC-electrospray ionisation mass spectrometry (HPLC-ESI-MS) in order to confirm the identity of the known siderophores, and to obtain the pseudo-molecular ions of unknown siderophore type chelates. A total of 22 different siderophore type chelates were resolved in the HPLC-ICP-MS chromatograms. Ten different siderophore type chelates were identified by HPLC-ESI-MS, 3 of which had not previously been identified in nutrient enriched seawater incubations. The concentration and diversity of siderophore type chelates was highest in seawater amended with glucose. The concentrations and diversity of siderophore type chelates also varied with biogeographical area in the Atlantic Ocean, with the North Atlantic Sub-tropical Gyre yielding highest concentrations in incubations, and the South Atlantic Sub-tropical Gyre and Western Tropical Atlantic yielding the highest diversity

Beschreibung: Predicting the ecological causes and consequences of global climate change requires a variety of approaches, including the use of experiments, models, and surveys. Among experiments, mesocosms have become increasingly popular because they provide an important bridge between smaller, more tightly controlled, microcosm experiments (which can suffer from limited realism) and the greater biological complexity of natural systems (in which mechanistic relationships often cannot be identified). A new evaluation of the contribution of the mesocosm approach, its potential for future research, as well as its limitations, is timely. As part of this review, we constructed a new database of over 250 post-1990 studies that have explored different components of climate change across a range of organisational levels, scales, and habitats. Issues related to realism, reproducibility and control are assessed in marine, freshwater, and terrestrial systems. Some general patterns emerged, particularly at the ecosystem level, such as consistent and predictable effects on whole-system respiration rates. There are, however, also many seemingly idiosyncratic, contingent responses, especially at the community level, both within and among habitat types. These similarities and differences in both the drivers and responses highlight the need for caution before making generalisations. Finally, we assess future directions and prospects for new methodological advances and the need for greater international coordination and interdisciplinarity.

Beschreibung: A comparative study of the mineralogy and geochemistry of sulfide deposits on mid-ocean ridges in the Northeast Pacific and the Mid-Atlantic reveals common characteristics associated with primary gold enrichment. Average gold contents of 0.8 to 5 ppm Au occur in sulfides from Southern Explorer Ridge and Axial Seamount (Northeast Pacific) and from the TAG hydrothermal field and Snakepit vent field (Mid-Atlantic Ridge). The enrichment of gold in these deposits is consistently related to a phase of late-stage, low-temperature (〈 300°C) venting. Concentrations 〉 1 ppm Au occur exclusively in pyritic assemblages and commonly with abundant Fe-poor sphalerite and a suite of complex Pb—Sb—As sulfosalts. Amorphous silica and, locally, barite or carbonate are important constituents of the gold-rich precipitates but do not contain gold themselves. High-temperature (350°C) black smoker assemblages, consisting dominantly of pyrite, chalcopyrite, pyrrhotite, isocubanite and abundant anhydrite are uniformly gold-poor (≤0.2 ppm Au). To the extent that individual sulfides can be mechanically separated, chemical analyses by neutron activation indicate that gold is most abundant in sphalerite (up to 5.7 ppm Au) but also occurs in pyrite and marcasite. Samples of sphalerite with abundant inclusions of fine-grained sulfosalts locally contain up to 18 ppm Au, suggesting that sulfosalts may be repositories for gold. No free gold has been observed at 4000 × magnification of polished specimens, indicating that the gold is present only as submicroscopic inclusions or as a chemical constituent within the sulfides. Samples from gold-rich deposits in the Northeast Pacific and Mid-Atlantic are compared with similar but relatively gold-poor sulfides from the Galapagos Rift and 13°N on the East Pacific Rise (EPR), and with barren sulfides from 11°N EPR, 21°N EPR, the Endeavour Ridge, and the Southern Juan de Fuca Ridge. Trace element analyses of more than 170 samples show that gold enrichment in almost all of the deposits is associated with high concentrations of Ag, As, Sb, Pb and Zn, and locally with high Cd, Hg, Tl, and Ga. In contrast, gold is typically depleted in samples with high Co, Se, and Mo. The close association of Au with Ag, As, Sb, and Pb may reflect the common behavior of these metals as aqueous sulfur complexes (e.g., [Au(HS)−2]) at low temperatures. Similar mineralogical and geochemical associations are observed in sulfide deposits from modern back-arc settings and in the ancient geologic record.

Beschreibung: Sixteen samples (588 individuals) of the Argentine shortfin squid Illex argentinus were collected by commercial vessels from Falkland and surrounding waters (42°06–51°17S) between February and May 1990 and subjected to starch gel electrophoresis. Levels of electrophoretically detectable generic variability and the extent of population differentiation were determined from allele frequencies at 25 enzyme-coding loci. Low levels of genetic variability were detected, with the overall proportion of polymorphic loci, P = 0.28, mean heterozygosities per locus, H1 = 0.011, and the average effective number of alleles, Nc = 1.23. Marked population differentiation was indicated by significant differences in allele frequency among samples, and unbalanced genotypic distributions with heterozygote deficits at most loci. Nei's mean genetic distances (D) and identities (I) ranged from 0.000 to 0.130 and 1.000 to 0.878, respectively, underlining the marked genetic divergence detected. Some evidence of microgeographic differentiation (between replicates within sites) was observed. Individuals collected from northerly limits of the sampled area (42: 06 S, 58:09 W) were most genetically distinct (I = 0.878−0.904), suggesting the existence of a hitherto unrecognised subspecies or species of Illex. Emphasis is placed on the need to delimit putative stock boundaries, and develop appropriate population models to ensure conservation of genetic resources.

Beschreibung: Highlights: • Mean circulation patterns are assessed and Kuroshio transport is underestimated. • Water mass distribution is compared and analyzed within COREII models. • Main biases of deep MLDs result from the inaccurate Kuroshio separation. • Reasonable modeled tropical dynamics but a discrepancy from the surface wind. Abstract: We evaluate the mean circulation patterns, water mass distributions, and tropical dynamics of the North and Equatorial Pacific Ocean based on a suite of global ocean-sea ice simulations driven by the CORE-II atmospheric forcing from 1963-2007. The first three moments (mean, standard deviation and skewness) of sea surface height and surface temperature variability are assessed against observations. Large discrepancies are found in the variance and skewness of sea surface height and in the skewness of sea surface temperature. Comparing with the observation, most models underestimate the Kuroshio transport in the Asian Marginal seas due to the missing influence of the unresolved western boundary current and meso-scale eddies. In terms of the Mixed Layer Depths (MLDs) in the North Pacific, the two observed maxima associated with Subtropical Mode Water and Central Mode Water formation coalesce into a large pool of deep MLDs in all participating models, but another local maximum associated with the formation of Eastern Subtropical Mode Water can be found in all models with different magnitudes. The main model bias of deep MLDs results from excessive Subtropical Mode Water formation due to inaccurate representation of the Kuroshio separation and of the associated excessively warm and salty Kuroshio water. Further water mass analysis shows that the North Pacific Intermediate Water can penetrate southward in most models, but its distribution greatly varies among models depending not only on grid resolution and vertical coordinate but also on the model dynamics. All simulations show overall similar large scale tropical current system, but with differences in the structures of the Equatorial Undercurrent. We also confirm the key role of the meridional gradient of the wind stress curl in driving the equatorial transport, leading to a generally weak North Equatorial Counter Current in all models due to inaccurate CORE-II equatorial wind fields. Most models show a larger interior transport of Pacific subtropical cells than the observation due to the overestimated transport in the Northern Hemisphere likely resulting from the deep pycnocline

Beschreibung: The rapid development of aquaculture has been considered the blue revolution, which is an approach to increasing global fish production in order to contribute to human nutrition and food security. The use of blue water (i.e., surface and groundwater) in aquaculture also makes a significant contribution to global fish production. However, the blue revolution of aquaculture is associated with a wide range of environmental concerns, including habitat destruction, water pollution, eutrophication, biotic depletion, ecological effects, and disease outbreaks. In addition, blue carbon (i.e., carbon in coastal and marine ecosystems) emissions from mangrove deforestation due to shrimp cultivation are accumulating. To increase fish production for a growing global population, aquaculture must grow sustainably while at the same time its environmental impacts must reduce significantly. There is blue growth potential for increasing seafood production through the expansion of coastal and marine aquaculture, which is essential for sustainable development of the blue economy.

Beschreibung: Ribosomally synthesized and post-translationally modified peptides (RiPPs) are an important class of natural products that contain antibiotics and a variety of other bioactive compounds. The existing methods for discovery of RiPPs by combining genome mining and computational mass spectrometry are limited to discovering specific classes of RiPPs from small datasets, and these methods fail to handle unknown post-translational modifications. Here, we present MetaMiner, a software tool for addressing these challenges that is compatible with large-scale screening platforms for natural product discovery. After searching millions of spectra in the Global Natural Products Social (GNPS) molecular networking infrastructure against just eight genomic and metagenomic datasets, MetaMiner discovered 31 known and seven unknown RiPPs from diverse microbial communities, including human microbiome and lichen microbiome, and microorganisms isolated from the International Space Station.

Beschreibung: Changes in environmental conditions can influence sponges and their holobionts. The present study investigated the effect of upwelling and anthropogenic pollution on the bioactivity of marine sponges, microbial communities and functional genes, and composition of their chemical compounds. The species Dysidea etheria, Darwinella sp., Hymeniacidon heliophila and Tedania ignis were collected from areas with distinct influence of upwelling and low anthropogenic impact and from areas without influence of upwelling but affected by sewage and the port. In most cases, the same sponge species collected from areas with distinct environmental conditions had a different chemical composition, antifouling activity, composition and diversity of associated microorganisms. Antimicrobial, quorum sensing inhibitory and anti-larval activities of sponge extracts were more pronounced in the area without upwelling showing higher level of anthropogenic pollution. This study suggests that upwelling and anthropogenic pollution affect the chemical activity and holobiome composition of sponges.