West Pacific Ocean Research Articles

Luteirhabdus pelagi gen. nov., sp. nov., a novel member of the family Flavobacteriaceae, isolated from the West Pacific Ocean

A Gram-stain-negative, aerobic, and yellow-pigmented bacterium, designated A3-108T, was isolated from seawater of the West Pacific Ocean. Cells were non-motile and rod-shaped, with carotenoid-type pigments. Strain A3-108T grew at pH 6.0–8.5 (optimum 6.5) and 15–40 °C (optimum 28 °C), in the presence of 0.5–10% (w/v) NaCl (optimum 1.0%). It possessed the ability to produce H2S. Based on the 16S rRNA gene analysis, strain A3-108T exhibited highest similarity with Aureisphaera salina A6D-50T (90.6%). Phylogenetic analysis shown that strain A3-108T affiliated with members of the family Flavobacteriaceae and represented an independent lineage. The principal fatty acids were iso-C15:0, iso-C17:0 3-OH, iso-C15:1 G, and summed feature 3 (C16:1ω7c and/or C16:1ω6c). The sole isoprenoid quinone was MK-6. The major polar lipids were phosphatidylethanolamine, one unidentified aminophospholipid, one unidentified aminolipid and one unidentified lipid. The ANIb, in silico DDH and AAI values among the genomes of strain A3-108T and three reference strains were 67.3–71.1%, 18.7–22.1%, and 58.8–71.4%, respectively. The G + C content was 41.0%. Distinctness of the phylogenetic position as well as differentiating chemotaxonomic and other phenotypic traits revealed that strain A3-108T represented a novel genus and species of the family Flavobacteriaceae, for which the name Luteirhabdus pelagi gen. nov., sp. nov. is proposed (type strain, A3-108T = CGMCC 1.18821T = KCTC 82563T).

Tabwecala robinsoni gen. nov., sp. nov., from Vanuatu and its systematic position in the ‘Ophiusini-Poaphilini’ clade (Lepidoptera, Erebidae)

A new erebid,Tabwecala robinsonigen. nov.,sp. nov., from the Vanuatu Islands (Espiritu Santo) (West Pacific Ocean) is described. The new species, superficially resembling species of the generaArtena,AchaeaorLeistera, shows a peculiar combination of characters which suggested its placement in a new genus. This is provisionally placed in tribe Poaphilini but following a review of the features purporting to show the separation of Ophiusini and Poaphilini, it is shown that morphological rationale supporting the current arrangement of these tribes is still lacking. Noteworthy modifications affect the hindleg of maleTabwecala robinsoni, with greatly shortened and swollen metatibia bearing a dorsal hair-pencil.

Evolution of Ocean Productivity in the Sub‐Tropical West Pacific Ocean Across the Last Deglaciation

AbstractChanges in marine export productivity may have played a prominent role in the atmospheric CO2 rise and associated warming of the last deglaciation, via their impact on the air‐sea partitioning of CO2. To study the evolution of marine export production in the western subtropical Pacific Ocean during the last deglaciation and the mechanisms governing these changes, 230Th‐normalization has been applied on a sediment core retrieved from the Okinawa Trough. The reconstructed export productivity record shows two prominent peaks, centered around 14 and 17 ka. Given that phytoplankton growth at our study site is limited by the availability of nutrients today, elevated macro‐nutrient supply must have been responsible for sustaining the two deglacial productivity peaks. Specifically, higher nutrient supply originating from the subpolar gyre via subsurface water advection, with enhanced vertical mixing in the subpolar gyre during early HS1 and enhanced wind‐driven upwelling during the B/A, would have fueled phytoplankton productivity and export. In contrast, reduced nutrient supply to the euphotic zone caused by gyre circulation changes would have lead to decreased export production during the Holocene. These observations lend support to a predominant control of nutrient availability on the evolution of the marine carbon cycle in the subtropical west Pacific Ocean across the last deglaciation.

A functional analysis reveals extremely low redundancy in global mangrove invertebrate fauna

Deforestation results in habitat fragmentation, decreasing diversity, and functional degradation. For mangroves, no data are available on the impact of deforestation on the diversity and functionality of the specialized invertebrate fauna, critical for their functioning. We compiled a global dataset of mangrove invertebrate fauna comprising 364 species from 16 locations, classified into 64 functional entities (FEs). For each location, we calculated taxonomic distinctness (Δ+), functional richness (FRi), functional redundancy (FRe), and functional vulnerability (FVu) to assess functional integrity. Δ+ and FRi were significantly related to air temperature but not to geomorphic characteristics, mirroring the global biodiversity anomaly of mangrove trees. Neither of those two indices was linked to forest area, but both sharply decreased in human-impacted mangroves. About 60% of the locations showed an average FRe < 2, indicating that most of the FEs comprised one species only. Notable exceptions were the Eastern Indian Ocean and west Pacific Ocean locations, but also in this region, 57% of the FEs had no redundancy, placing mangroves among the most vulnerable ecosystems on the planet. Our study shows that despite low redundancy, even small mangrove patches host truly multifunctional faunal assemblages, ultimately underpinning their services. However, our analyses also suggest that even a modest local loss of invertebrate diversity could have significant negative consequences for many mangroves and cascading effects for adjacent ecosystems. This pattern of faunal-mediated ecosystem functionality is crucial for assessing the vulnerability of mangrove forests to anthropogenic impact and provides an approach to planning their effective conservation and restoration.

Physiological and genomic features of Henriciella with the description of Henriciella mobilis sp. nov.

Strains M65T, M69 and JN25 were isolated from seawater of the West Pacific Ocean. Cells of the three strains were Gram-stain-negative, aerobic and rod-shaped. Cells were motile by means of flagella. On the basis of the results of 16S rRNA gene sequence analysis, strains M65T, M69 and JN25 showed the highest 16S rRNA gene sequence similarity to Henriciella algicola MCS27T (98.8 %), followed by Henriciella marina DSM 19595T (98.4 %), Henriciella barbarensis MCS23T (98.4 %), Henriciella pelagia LA220T (98.3 %), Henriciella aquimarina P38T (98.1 %) and Henriciella litoralis SD10T (97.8 %). The 16S rRNA gene sequence similarities among the isolates were 100 %. Phylogenetic analyses revealed that the isolates fell within a cluster comprising the Henriciella species and represented an independent lineage. The average nucleotide identity and in silico DNA-DNA hybridization values between strain M65T and the type strains of Henriciella species were 73.9-85.8 % and 19.9-22.4 %, respectively. The sole respiratory quinone detected in the three isolates was ubiquinone 10. The principal fatty acids were summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c) and C16 : 0. The major polar lipids were glucuronopyranosyldiglyceride, monoglycosyldiglyceride and one unidentified glycolipid. The DNA G+C content was 61.3-61.4 mol%. Phylogenetic distinctiveness, chemotaxonomic differences, together with phenotypic properties, revealed that the isolates could be differentiated from the Henriciella species with validly published names. Therefore, it is proposed that strains M65T, M69 and JN25 represent a novel species of the genus Henriciella, for which the name Henriciella mobilis sp. nov. (type strain, M65T=CGMCC 1.15927T=KCTC 52576T) is proposed.

Relative humidity and agricultural activities dominate wildfire ignitions in Yunnan, Southwest China: Patterns, thresholds, and implications

Wildfires are land-surface processes and ecological disturbances occurring around the world. The wildfire regime in Yunnan Province of Southwest China is recognized as similar to that of the adjoining Indo-China Peninsula, a global hotspot for wildfires. However, the ignition mechanisms in this region remain unclear, with interactions among ecosystem features, local agricultural activities, and fire weather controlled by the West Pacific and Indian Ocean monsoons. Based on the ground records of 5145 confirmed wildfire events in Yunnan during the period of 2003–2015, we used a logistic regression model to estimate the local environmental controls on wildfire ignitions. Results highlighted the primary role of meteorology-driven characters, especially the prevalent importance of daily minimum relative humidity across the region. The threshold of the relative humidity was 37.48% ± 15.60% for the 50% ignition probability. Relative humidity also dominated ignition over years, with fuel conditions relatively stable and playing a minor role in contrast to the inter-annual climate changes. Moreover, agriculture-related ignition comprised most wildfire records, and human activities deeply shaped the spatiotemporal patterns of ignition. The distance to the nearest village was the primary factor during the beginning of the agricultural season, with a farming radius of 1.2 km as a key threshold for ignition. The complementary roles among influential factors were prominent at county scale. Among counties, the variation of ignition mechanisms corresponded to the influence paths of the two monsoons. This study highlights the importance of ground wildfire records in deriving critical wildfire ignition information such as environmental thresholds and change rates, which can provide important insights for sustainable forest management in this region, including wildfire monitoring, ignition control, fuel structure adjusting, and implementing differentiated strategies for fire prevention with regard to the environmental contexts.

Occurrence, distribution and risk assessment of organophosphate ester flame retardants and plasticizers in surface seawater of the West Pacific

Twenty-eight samples of surface seawater were collected from the West Pacific Ocean during 2019 using a high-volume solid-phase extraction with high-throughput organic analysis (Hi-throat/Hi-volume SPE) method, and concentrations of 10 organophosphate ester flame retardants and plasticizers (OPEs) were determined. The total OPE concentration in the samples was 3.02–48.4 ng L−1 (mean 25.0 ± 10.5 ng L−1), with tris(2-chloroethyl) phosphate (TCEP) being the largest contributor. Cluster analysis results showed off-shore input from the coast of East and Southeast Asia was an important source of these chemicals. Tri-p-tolyl phosphate (TpTP) should also be considered for long-term monitoring, because of its high detection frequency. Results of a risk assessment indicated low ecological risk to species in the West Pacific Ocean for TPhP and ΣOPEs. Hazard quotients (HQs) were all <1, indicating that the health risk to humans from these chemicals was at acceptable levels.

Okinawa Trough Geophysical and Topographic Modeling by GDAL Utilities and GRASS GIS

This paper presents using GDAL utilities and GRASS GIS for topographic analysis of the raster grids based on GEBCO DEM as NetCDF file at 15 arc-second intervals. The focus study area encompasses the area around Okinawa Trough, Ryukyu trench-arc system, southern Japan, East China Sea and the Philippine Sea, west Pacific Ocean. Several GDAL utilities were applied for data processing: gdaldem, gdalwarp, gdalinfo, gdal_translate. The data were imported to GRASS GIS via r.in.gdal. Data visualization highlighted high resolution and accuracy of GEBCO grid, enabling topographic modelling at the advanced level. The algorithm of DEM processing, implemented in GDAL utility gdaldem, was used for generating multi-purpose topographic models: aspect, hillshade, roughness and topographic indices, such as Topographic Position Index (TPI), Terrain Ruggedness Index (TRI). Thematic maps (topography, geoid, marine free-air gravity) were visualized using GRASS GIS modules for raster (d.rast, r.colors, r.contour) and vector (d.vect, v.in.region, d.legend) data processing. The results demonstrated smoother bathymetry in the East China Sea and rugged relief in the Philippine Sea which corresponds to their different geological and geophysical settings. The presented methodology of the topographic analysis based on DEM demonstrated technical aspects of GDAL and GRASS as scripting approach of advanced cartography.

Temperature Gradients Across the Pacific Ocean During the Middle Miocene

AbstractSea surface temperatures (SSTs) of the tropical Pacific Ocean exert powerful controls on regional and global climates. Previous studies have suggested that during warm climate phases, the east‐west temperature gradient collapsed. To date, there has been no high‐resolution reconstruction of sea surface conditions in both the east and west Pacific Ocean during the Miocene Climate Optimum (MCO) and across the middle Miocene climate transition (MMCT); therefore, our understanding of the mean oceanographic state during this major global climatic shift is limited. Here, we present new SST reconstructions for the eastern Pacific Ocean (15.5–13.3 Ma) which show a clear east‐west temperature gradient of ∼4°C during the warmest interval of the Neogene, implying that the oceanographic processes that produce the modern gradient were present and active. There is no shift in the east‐west gradient across the MMCT indicating that the gradient was not impacted by global cooling and ice growth. We find a 2°C sea surface cooling in the eastern equatorial Pacific, that lags the benthic foraminiferal δ18O positive shift by 150 kyr, indicating that tropical temperature did not decrease synchronously with the expansion of the Antarctic ice sheet. Reconstructed variations in the δ18O composition of seawater, determined by combining our Mg/Ca and δ18O records, reveal a freshening in the eastern Pacific Ocean after 13.8 Ma, suggesting changes in the hydrological cycle and in tropical fronts in response to the new icehouse regime.

Trace Elemental Analysis of the Exoskeleton, Leg Muscle, and Gut of Three Hadal Amphipods.

Hadal trenches are the deepest areas worldwide. Amphipods are considered a key factor in hadal ecosystems because of their important impacts on the hadal environment. Amphipods have benthic habits, and therefore, serve as good metal biomonitors. However, little is known about the hadal amphipod metal accumulations. In the present study, Alicella gigantea, Hirondellea gigas, and Scopelocheirus schellenbergi were sampled from the New Britain Trench (8824m, 7.02S 149.16E), Mariana Trench (10,839m, 11.38N 142.42E), and Marceau Trench (6690m, 1.42N 148.74E) in the West Pacific Ocean, respectively. The elemental concentrations of the three hadal amphipods were subsequently investigated. Nine trace elements (V, Cr, Mn, Co, Ni, Se, Mo, Ag, and Cd) of three tissues (exoskeleton, leg muscle, and gut) of the hadal amphipods were detected by using inductively coupled plasma mass spectrometry (ICP-MS) method. The concentrations of Cr, Cd, and Mn were comparably higher among those nine examined elements. The greatest accumulations of the elements Cr, Ag, and V in the exoskeleton and leg muscle were observed in H. gigas, and elements Mn, Co, and Se showed the highest accumulations in the gut in H. gigas among the three hadal amphipods. In addition, comparisons of the leg muscle trace element accumulation between the hadal amphipods and non-abyssal and shallow water decapoda and amphipoda species showed that the hadal amphipods possessed comparably higher concentrations of the trace elements Cd, Co, Mo, Ag, and V. This finding suggested a bottom-up effect of food availability and indicated the effects of human activities within the hadal environments. This study reveals the trace element bio-accumulation of three hadal amphipods, and suggests that deep-sea amphipods are potential indicator species for trace element bioavailability in the deep-sea environment.

Alterinioella nitratireducens gen. nov., sp. nov., Isolated from Seawater in the West Pacific Ocean.

A novel Gram-negative, nonspore forming, nonmotile, and short-rod-shaped aerobic bacterium, designated DY48A3-103T, was isolated from a seawater sample collected from the West Pacific Ocean. Strain DY48A3-103T showed oxidase-positive and catalase-positive activities. Growth was observed at 10-37°C (optimum 30°C), at pH 6.5-9.5 (optimum 8.0) and in 1-11% NaCl (optimum 3%, w/v). 16S rRNA gene sequence analysis exhibited 96.3%, 96.1%, 96.0%, and 94.9% sequence similarity to the type strains Rhodophyticola porphyridii MA-7-27T, Nioella sediminis JS7-11T, N. nitratireducens SSW136T, and Jannaschia helgolandensis DSM 14858T, respectively. Strain DY48A3-103T and the type strains of phylogenetically related species have 61.7-75.4% AAI values, which fell into to the genus boundary range (60-80% AAI). Phylogenetic trees based on the 16S rRNA gene sequences and the genome sequences of strain DY48A3-103T revealed that it was affiliated to the members of the family Rhodobacteraceae. The G+C content was 65.4%. The sole isoprenoid quinone was Q-10. The predominant polar lipids were phosphatidylcholine and phosphatidylglycerol.Major fatty acids were summed feature 8 (comprising C18:1ω7c and/or C18:1ω6c), C19:0 cyclo ω8c, and C16:0. On the basis of the phenotypic, chemotaxonomic, and genomic properties, strain DY48A3-103t is proposed to represent a novel genus and a novel species, Alterinioella nitratireducens gen. nov., sp. nov., in the family Rhodobacteraceae. The type strain is DY48A3-103T (= KCTC 72738T = MCCC 1K04322T).

Coiling directions in the planktonic foraminifer Pulleniatina: A complex eco-evolutionary dynamic spanning millions of years.

Planktonic foraminifera are heterotrophic sexually reproducing marine protists with an exceptionally complete fossil record that provides unique insights into long-term patterns and processes of evolution. Populations often exhibit strong biases towards either right (dextral) or left (sinistral) shells. Deep-sea sediment cores spanning millions of years reveal that some species show large and often rapid fluctuations in their dominant coiling direction through time. This is useful for biostratigraphic correlation but further work is required to understand the population dynamical processes that drive these fluctuations. Here we address the case of coiling fluctuations in the planktonic foraminifer genus Pulleniatina based on new high-resolution counts from two recently recovered sediment cores from either side of the Indonesian through-flow in the tropical west Pacific and Indian Oceans (International Ocean Discovery Program Sites U1486 and U1483). We use single-specimen stable isotope analyses to show that dextral and sinistral shells from the same sediment samples can show significant differences in both carbon and oxygen isotopes, implying a degree of ecological separation between populations. In one case we detect a significant difference in size between dextral and sinistral specimens. We suggest that major fluctuations in coiling ratio are caused by cryptic populations replacing one another in competitive sweeps, a mode of evolution that is more often associated with asexual organisms than with the classical ‘biological species concept’.

Stable Biological Production in the Eastern Equatorial Pacific Across the Plio‐Pleistocene Transition (∼3.35–2.0 Ma)

AbstractUpwelling within the Eastern Equatorial Pacific (EEP) Ocean is a key factor for the Earth's climate because it supports &gt;10% of the present‐day biological production. The dynamics of upwelling in the EEP across the Plio‐Pleistocene transition—an interval particularly relevant for understanding near‐future warming due to Anthropocene‐like atmospheric carbon‐dioxide levels—have been intensively studied for the region east of the East Pacific Rise. In contrast, changes of the equatorial upwelling regime in the open Pacific Ocean west of this oceanographic barrier have received markedly less attention. We therefore provide new proxy records from Ocean Drilling Program Site 849 located within the EEP open‐ocean upwelling regime. Our target interval (∼3.35–2.0 Ma) covers the Plio‐Pleistocene transition characterized by the intensification of Northern Hemisphere Glaciation (iNHG). We use benthic δ18O values to generate a new, high‐resolution age model for Site 849, and sand‐accumulation rates together with benthic δ13C values to evaluate net export production. Although showing temporary substantial glacial‐interglacial variations, our records indicate stability in net export production on secular timescales across the iNHG. We suggest the following processes to have controlled the long‐term evolution of primary productivity at Site 849. First, nutrient export from the high latitudes to the EEP; second, a successive shoaling of the Pacific nutricline during the studied interval; and third, a simultaneous reduction in dust‐borne iron input.

Meta-analysis of the response of marine phytoplankton to nutrient addition and seawater warming

As an indispensable part of the marine ecosystem, phytoplankton are important prey for zooplankton and various marine animals with important commercial value. The influence of seawater warming and eutrophication on phytoplankton communities is well known, but few studies have explained the effects of the interaction between temperature and nutrients on marine phytoplankton. Through meta-analysis and meta-regression, the phytoplankton responses to the effects of nutrient addition and seawater warming were evaluated in this study. Nitrogen (N) addition led to an increase in phytoplankton biomass, while phosphorus (P) had no significant effect on phytoplankton biomass. However, this result may be biased by the uneven distribution of the research area. N limitation is widespread in the areas where these collected studies were conducted, including many parts of North and South Atlantic and West Pacific Oceans. The key limiting nutrient in other areas lacking corresponding experiments, however, remain unclear. The effect of seawater warming was not significant, which indicates the uncertainty about the effect of temperature on phytoplankton. The results of ANOVA show that nutrient addition and seawater warming had similar effects in various marine habitats (coastal regions, estuaries and open seas), while salinity could have caused the difference in the N effects among the three habitats. Furthermore, our results showed that the impact of temperature depends on nutrient conditions, especially N status, which has rarely been considered before. This result demonstrated the importance of evaluating nutrient limitation patterns when studying climate warming. The impact of rising temperatures may need to be reevaluated because N limitation is common.

Phylogeography of two marine predators, giant trevally (Caranx ignobilis) and bluefin trevally (Caranx melampygus), across the Indo-Pacific

For economically valuable marine fishes, identifying biogeographic barriers and estimating the extent of gene flow are critical components of fisheries management. We examined the population genetic structure of two commercially important reef-associated predators, the giant trevally ( Caranx ignobilis) and bluefin trevally (Caranx melampygus). We sampled 225 individuals and 32,798 single nucleotide polymorphisms (SNPs) of C. ignobilis, and 74 individuals and 43,299 SNPs of C. melampygus. Analyses of geographic population structure indicate the two species display subtly different phylogeographic patterns. Caranx ignobilis comprises two to three putative populations—one in the Central Pacific, one inhabiting the Western Pacific and Eastern Indian oceans, and one in the Western Indian Ocean—with some restricted gene flow between them. Caranx melampygus shows evidence of restricted gene flow from Hawaii to the West Pacific and Indian oceans, as well as limited genetic connectivity across the Indo- Pacific Barrier. Both species exhibit patterns characteristic of other large, reef-associated predators such as deepwater snappers and the great barracuda. This study contributes to ongoing assessments of the role of the Indo-Pacific Barrier in shaping patterns of phylogeography for large reef-associated fishes. Furthermore, by identifying putative populations of C. ignobilis and C. melampygus in the Central Pacific, our findings serve to improve future management measures for these economically important, data-limited species, particularly in light of historic and contemporary overfishing in Hawaii.

Distribution of Chromophytic Phytoplankton in the Eddy-Induced Upwelling Region of the West Pacific Ocean Revealed Using rbcL Genes.

Marine chromophytic phytoplankton are a diverse group of algae and contribute significantly to the total oceanic primary production. However, the spatial distribution of chromophytic phytoplankton is understudied in the West Pacific Ocean (WPO). In this study, we have investigated the community structure and spatial distribution of chromophytic phytoplankton using RuBisCO genes (Form ID rbcL). Our results showed that Haptophyceae, Pelagophyceae, Cyanophyceae, Xanthophyceae, and Bacillariophyceae were the dominant groups. Further, chromophytic phytoplankton can be distinguished between upwelling and non-upwelling zones of the WPO. Surface and 75 m depths of a non-upwelling area were dominated by Prochlorococcus strains, whereas chromophytic phytoplankton were homogenously distributed at the surface layer in the upwelling zone. Meanwhile, Pelagomonas-like sequences were dominant at DCM (75 m) and 150 m depths of the upwelling zone. Non-metric multidimensional scaling (NMDS) analysis did not differentiate between chromophytic phytoplankton in the upwelling and non-upwelling areas, however, it showed clear trends of them at different depths. Further, redundancy analysis (RDA) showed the influence of physicochemical parameters on the distribution of chromophytic phytoplankton. Along with phosphate (p < 0.01), temperature and other dissolved nutrients were important in driving community structure. The upwelling zone was impacted by a decrease in temperature, salinity, and re-supplement of nutrients, where Pelagomonas-like sequences outnumbered other chromophytic groups presented.

Variability of West Pacific subtropical high and its potential importance to the Indian summer monsoon rainfall

AbstractThe variability of West Pacific subtropical high (WPSH) during the peak monsoon (July–August) season for the period 1951–2015 and its association with Indian summer monsoon rainfall (ISMR) is investigated based on various observational data sets. In the present study, we explored the long term variability of WPSH based on location index (zonal displacement of western edge) and intensity index (intensity values at the centre of WPSH). We observed significant interannual variability in zonal displacement of western flank at around 20°N, and this variability is coherent with the variability in intensity at the centre of WPSH. The significant long term trend in location index is about 1.4° per decade towards east, which is also consistent with weakening trend (−2.6 gpm per decade) in intensity index. Moreover, both the indices show contrasting trends prior to and post 1976 periods. The variability of location and intensity indices shows significant relationship with ISMR by modulating the low level circulations over the Indo‐Pacific region. The present study revealed that the correlations of WPSH indices with ISMR are significant at 95% confidence level. The spatial distribution of rainfall over India during WPSH expansion years depicts the significant enhancement in southern peninsula and north‐central India while a significant reduction in east central India; however, contrasting rainfall patterns are observed during WPSH contraction years. In general, changes in large‐scale circulation during the westward (eastward) shift and intensification (weakening) of WPSH favour (unfavour) monsoon rainfall. The southern peninsula and northcentral India (east central India) experience surplus (deficit) rainfall during WPSH expansion due to modulation of moisture supply from the Arabian Sea, Bay of Bengal and west Pacific Ocean. Additionally, we noticed upper (lower) level divergence (convergence) and lower (upper) level convergence (divergence) during the expansion (contraction) years over the south Asian monsoon region.

Disentangling magnetic and environmental signatures of sedimentary 10Be/9Be records

Reconstructions of the global production rate of the cosmogenic isotope 10Be from sedimentary records of authigenic 10Be/9Be ratios have been successfully used to obtain independent estimates of geomagnetic dipole moment variations caused by field excursions or reversals. In this study, we assess the reliability of 10Be/9Be as a proxy for the cosmogenic 10Be production rate by evaluating two potential biasing sources represented by sediment composition and climatic modulation. For this purpose, we compare five high-resolution 10Be/9Be records of the Matuyama-Brunhes (M-B) field reversal from sediment cores of the Indian, West Pacific, and North Atlantic oceans. Significant increase of 10Be/9Be ratios at ∼774 ka is explained in terms of the dominant control of geomagnetic modulation during the M-B reversal. Results do not support the existence of a direct proportionality between measured sedimentary 10Be/9Be ratio and cosmogenic 10Be production rate, as shown by 10Be/9Be records that offset relative to each other during and outside the M-B reversal.Residual differences between offset-corrected rescaled records do not appear to be related to an incomplete correction of variable sediment scavenging efficiencies by 9Be normalization. Instead, these differences can be explained by a common climatic modulation model, assuming a linear relation between 10Be/9Be and the global 10Be production rate with site- and time-dependent additive and multiplicative coefficients. These coefficients are linear functions of a single global climate proxy identified with the benthic δ18O record. Additive coefficients are almost constant in time and can represent up to ∼60% of the average 10Be/9Be value during periods of stable field polarity. Multiplicative coefficients are also site-specific, with mean values representing the bulk scavenging efficiency of the site, and variations about this mean expressing a multiplicative climatic modulation of the 10Be production rate. The amplitude of this modulation amounts to 10–15% of the maximum variations recorded during the M-B reversal and is sufficiently large to mask minor variations of the dipole moment during stable polarity periods. Reconstructions of the geomagnetic dipole intensity can benefit from the information about climatic modulation effects gained with our modelling approach. Best suited sites for magnetic field reconstructions should be characterized by minimal Be-recycling contributions from ancient 10Be reservoirs and minimal climatic modulation, as far as it can be determined from relative comparisons with other records. These conditions are most likely encountered in open basins at sites (1) with < 2.8 km water depth, (2) > 200 km offshore, and (3) located underneath a large current system extending over regions with minimum terrigenous inputs. Scaling all records with respect to a chosen reference enables to produce 10Be/9Be stacks with reduced noise and short-term local environmental effects. Differences between stacks obtained in this manner highlight global climatic effects that need to be considered when generating calibrated reconstructions of the geomagnetic dipole moment.

Alcanivorax profundimaris sp. nov., a Novel Marine Hydrocarbonoclastic Bacterium Isolated from Seawater and Deep-Sea Sediment

Two novel Alcanivorax-related strains, designated ST75FaO-1T and 521-1, were isolated from the seawater of the South China Sea and the deep-sea sediment of the West Pacific Ocean, respectively. Both strains are Gram-stain-negative, rod-shaped, and non-motile, and grow at 10-40°C, pH5.0-10.0, in the presence of 1.0-15.0% (w/v) NaCl. Their 16S rRNA gene sequences showed 99.9% similarity. Phylogenetic analysis based on the 16S rRNA gene sequences indicated that both strains belong to the genus Alcanivorax, and share 92.9-98.1% sequence similarity with all valid type strains of this genus, with the highest similarity being to type strain Alcanivorax venustensis DSM 13974T (98.0-98.1%). Digital DNA-DNA hybridization (dDDH) and average nucleotide identity values between strains ST75FaO-1T and 521-1 were 75.7% and 97.1%, respectively, while the corresponding values with A. venustensis DSM 13974T were only 25.4-25.6% and 82.4-82.7%, respectively. The two strains contained similar major cellular fatty acids including C16:0, C18:1 ω7c/ω6c, C19:0 cyclo ω8c, C16:1 ω7c/ω6c, C12:0 3-OH, and C12:0. The genomic G + C content of strains ST75FaO-1T and 521-1 were 66.3% and 66.1%, respectively. Phosphatidylglycerol, phosphatidylethanolamine, two unidentified phospholipids, and one unidentified polar lipid were present in both strains. On the basis of phenotypic and genotypic characteristics, the two strains represent a novel species within the genus Alcanivorax, for which the name Alcanivorax profundimaris sp. nov. is proposed. The type strain is ST75FaO-1T (= MCCC 1A17714T = KCTC 82142T).

Taxonomy of the genus Dactylanthias Bleeker (Teleostei: Serranidae: Anthiadinae).

The anthiadine genus Dactylanthias is reviewed. Two species, Dactylanthias aplodactylus (Bleeker, 1858) and Dactylanthias baccheti Randall, 2007 are currently recognised, each known only from their holotypes. A specimen of Dactylanthias matching D. baccheti in coloration was recently collected from Nauru in the West Pacific Ocean. It was retained by a recreational fisher and deposited into the CSIRO Australian National Fish Collection, Hobart. Data collected from this specimen and comparison to images of and data from the holotypes of both nominal species indicate that Dactylanthias baccheti Randall, 2007 is a junior synonym of Dactylanthias aplodactylus (Bleeker, 1858). Additional records of specimens from Ambon, Indonesia (type locality of D. apolodactylus) and the Maldives Islands, Indian Ocean are reported. The genus is briefly compared with other anthiadine genera.