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The present study distinguishes the different effects of the eastern Pacific-type (EP-type) sea surface temperature anomaly (SSTA) and the central Pacific-type (CP-type) SSTA on the tropical easterly jet (TEJ) by dividing the TEJ into the entrance (over the tropical western Pacific), core (over the tropical Indian Ocean) and exit regions (over equatorial Africa and the Atlantic). It is found that the EP-type SSTA can exert an inverse influence on the intensity of the TEJ between its exit-core region and the entrance region, while the CP-type SSTA mainly affects the entrance of the TEJ. This discrepancy can be attributed to the different magnitude and spatial extension of the diabatic heating associated with the enhanced precipitation induced by the two SSTA patterns. The EP-type SSTA could induce a stronger and wider-spread positive precipitation anomaly over the tropical Pacific than the negative precipitation anomaly over the Maritime Continent, while the CP-type SSTA can induce an enhanced precipitation over the tropical Pacific that is roughly equivalent in amplitude and spatial extension to the suppressed precipitation over the Maritime Continent. Thus, the EP-type SSTA can affect the entire TEJ through the dominant diabatic heating in the tropical Pacific and its subsequent Gill-Matsuno response, accelerating the entrance region and slowing the exit-core region. In contrast, the CP-type SSTA could only produce a significant acceleration in the entrance of the TEJ as the remote effect of the diabatic heating in the tropical Pacific is nearly neutralized by the diabatic cooling in the Maritime Continent. A series of numerical experiments based on a linear baroclinic model confirms the above conclusions and distinguishes between the independent contributions of the diabatic heating in the tropical Pacific and the diabatic cooling in the Maritime Continents to the TEJ. [ABSTRACT FROM AUTHOR]

Bonefishes are a nearshore species targeted by non-commercial anglers and subsistence fishers in the Central and South Pacific islands. Among the bonefish species in the Indo-Pacific region, Albula glossodonta are known to have one of the widest geographic ranges, from the Red Sea to the Central Pacific, but it is unknown how dispersive A. glossodonta are between geographically isolated islands. Volunteer anglers collected A. glossodonta fin clips from the main Hawaiian Islands in the North Pacific, Anaa Atoll in the South Pacific, and intermediate Kiritimati Island (Line Islands) to assess the scale of dispersal and population structure within the Pacific Ocean. Population genomics was conducted based on 208 individuals and 7225 SNPs. Although adult A. glossodonta exhibit strong site fidelity, genomic results show no population differentiation between Oahu and Maui in Hawai'i. Bonefishes exhibit significant population structure between Anaa and Hawai'i (FST = 0.096), with intermediate Kiritimati comprising admixed fishes. A lengthy larval duration likely promotes connectivity between Pacific islands. Regional management regimes may be most appropriate for a species with this level of dispersal. [ABSTRACT FROM AUTHOR]

The occurrence and seasonality of the Critically Endangered great hammerhead shark, Sphyrna mokarran, is data deficient in the Central Pacific region. Using photo-identification and laser-photogrammetry, we describe the seasonal population of great hammerhead sharks in the Tiputa pass (Rangiroa atoll) and Tuheiava pass (Tikehau atoll) in the Tuamotu archipelago of French Polynesia. During the austral summer of 2020 and 2021, we recorded a female-biased aggregation of at least 55 individuals (54 females; 1 unknown sex), representing an unprecedented number of S. mokarran in one study. All measured sharks were likely mature with pre-caudal lengths ranging from 147 cm to 297 cm (n = 35). Videos from citizen scientists recorded over a 15-year period enable us to identify 30 additional individuals between 2006 and 2019, with strong evidence of sexual segregation during the year. Our findings revealed seasonal residency (n = 32) of up to 6 days/month and for up to 5 months at the study site during the austral summer. We also demonstrated site fidelity with 32 individuals returning to the same atoll for up to 12 years between the first and last sighting, and with limited evidence of connectivity between the two sites. Our analysis also provides preliminary insight into the environmental factors driving S. mokarran aggregation in the Tiputa pass, suggesting a marked influence of the lunar cycle and of ocellated eagle rays (Aetobatus ocellatus) abundance. This study, conducted in situ with non-invasive methods offers a unique opportunity to study a great hammerhead shark population in a near-pristine ecosystem and provides important life-history elements for the Central Pacific region.

An underlying form like /maːli/ is problematic for a stress system requiring word-final, bimoraic trochees. The grammar must sacrifice word-finality or bimoraicity, [(máː)li] or [(máːli)] (tolerating HL#); place stress on the second half of the long vowel, [ma(áli)] (breaking); or shorten the vowel, [(máli)] (trochaic shortening). This article surveys the Central Pacific language family, which hosts the most famous cases of breaking (Tongan) and trochaic shortening (Fijian), and finds that while trochaic shortening is poorly attested, breaking and tolerance are common. There are three findings of theoretical interest. First, length alternations suggest it is difficult to learn contrastive information that is absent in the core member of the morphological paradigm. Second, lexicalization of whole words is a possible response to this difficulty. Third, there is divergence between a language’s root phonotactics and its alternations.

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Ocean warming is causing declines of coral reefs globally, raising critical questions about the potential for corals to adapt. In the central equatorial Pacific, reefs persisting through recurrent El Niño heatwaves hold important clues. Using an 18‐year record of coral cover spanning three major bleaching events, we show that the impact of thermal stress on coral mortality within the Phoenix Islands Protected Area (PIPA) has lessened over time. Disproportionate survival of extreme thermal stress during the 2009–2010 and 2015–2016 heatwaves, relative to that in 2002–2003, suggests that selective mortality through successive heatwaves may help shape coral community responses to future warming. Identifying and facilitating the conditions under which coral survival and recovery can keep pace with rates of warming are essential first steps toward successful stewardship of coral reefs under 21st century climate change. Plain Language Summary: Mass bleaching events caused by warming oceans and intensifying marine heatwaves have killed millions of corals globally. In the central equatorial Pacific, coral reefs experienced three extreme heatwaves within 15 years, providing valuable insights into the mechanisms that could facilitate coral survival under global warming. We examined an 18‐year record of coral cover in the Phoenix Islands Protected Area (PIPA) to track the community response to each event. In the 2002/2003 heatwave, coral communities across PIPA were decimated, with some reefs experiencing near complete mortality. Strong recovery followed and in 2009/2010, a heatwave of similar magnitude caused minimal mortality. The 2015/2016 heatwave was the strongest on record, exposing PIPA's coral communities to twice the thermal stress of 2002/2003. Yet coral mortality during this event was disproportionately low. An examination of 11 environmental metrics that may have modulated the impacts of extreme heat revealed no consistent explanation. Rather, our results support the hypothesis that the survival of thermally tolerant colonies in 2002/2003 and localized recruitment, facilitated recovered communities with greater thermal tolerance than those that inhabited the reefs two decades ago. Understanding and promoting the conditions that facilitate coral recovery and adaptation would enhance our ability to foster coral reef survival. Key Points: An 18‐year record of coral cover spanning three strong El Niño heatwaves reveals a weakening impact of thermal stress over timeCoral communities recovered from the catastrophic 2002/2003 heatwave suffered lower mortality in 2015/2016 despite a doubling of thermal stressA decoupling of coral mortality and thermal stress suggests repopulation by thermally tolerant survivors may aid adaptation to ocean warming [ABSTRACT FROM AUTHOR]

Two strong earthquakes occurred on November 13, 2017, 02:28:20 (Esterillos Earthquake) and August 24, 2020 at 21:51:08 (Herradura Earthquake) in the Central Pacific of Costa Rica and are analyzed in this work. Herradura earthquake was located at latitude 9.501° N, longitude 84.665° W, with centroid at 25 km depth, Mw 5.9, and +1.3 seconds after the origin time. It is associated with an inverse fault striking northwest (311°), dipping to the northeast at a low angle of 20° and with a slip angle of 98°. The earthquake was reported felt from strong to very strong; keeping a close relation with the peak accelerations (PGA) registered instrumentally; this data allowed determined that the maximum intensity in the scale of Modified Mercalli (MMI) was of VI, corresponding to 12%g. Esterillos earthquake, was located 14 km southeast of the Herradura earthquake, with centroid at 21 km depth, Mw 6.4. The chosen fault plane where the event originated is striking 289° to the NW, dipping 17° to the northeast and with a slip angle of 85°, with circular form slip distribution, reaching maximum of 0.6 m around the centroid and with a radius of ~8 km. These earthquakes are located at the seismic interface of the Cocos and Caribbean plates (COCA) and most of the aftershocks were recorded in the first 25 km depth and with epicenters between the coast and the Middle America Trench (MAT). Cortical Caribbean events were located after the Esterillos event and close to it epicenter, the transtensional deformation in the continental Esterillos epicentral area and confirmed with calculated focal mechanism for some of these events could be related to subducted seamount in the zone. [ABSTRACT FROM AUTHOR]

Using an extended 120‐year record of El Niño events, we distinguish between central Pacific (CP) and eastern Pacific (EP) types to show that the strength of CP events is a factor in the amplitude and sign of the impact on rainfall over southeastern Australia. Both weak and strong CP events cause widespread rainfall deficits in Australia during the onset phase from April to September. However, this relationship reverses over southeastern Australia including the Murray Darling Basin river catchment region for the strongest CP events after October, leading to positive rainfall anomalies during the mature phase of strong CP El Niños. This reversal can be explained by a change in the circulation over eastern Australia from drier, more westerly orientated flow to moister, more easterly onshore flow. These findings may help with seasonal prediction efforts to predict drought‐breaking rain such as occurred in early 2020. Plain Language Summary: El Niño Southern Oscillation events are extremely important for many countries around the world due to their impacts on rainfall. By separating El Niño into central Pacific (CP) and eastern Pacific (EP) events, we show that the strength of a CP event controls the rainfall amount for southeastern Australia. The stronger a CP event is, the drier it is over Australia during the onset phase from April to September. But after October during the mature phase of El Niño, the strongest CP events lead to more rainfall than normal over the southeast Australian river catchment known as the Murry Darling Basin, whereas the weakest CP events lead to less rainfall than normal. This relationship is strongest in January to March around the time that the CP event is fully developed. For the strongest CP events, this can be explained by a change in the circulation from drier, more westerly flow during the onset phase to moister, more easterly onshore flow during the mature phase. This finding is important for agricultural and water resources planning efforts in the Murry Darling Basin region and may help with seasonal prediction efforts to predict drought‐breaking rain such as occurred in early 2020. Key Points: The strength of central Pacific (CP) El Niño events has a significant impact on rainfall over southeastern AustraliaStrong CP events cause Australian rainfall deficits during onset but enhanced rainfall over southeastern Australia during the mature phaseThis can be explained by a circulation change over eastern Australia from drier, more westerly flow to moister, more easterly onshore flow [ABSTRACT FROM AUTHOR]

Scutellastra mexicana is the largest species of giant limpet in the world. This species is distributed along the tropical Mexican Pacific and is now considered extinct in some areas of the region.In prehispanic Mexico, this limpet was used for food, ornamentation, and in mortuary offerings. More recently, its meat has been highly valued for human consumption. During the 1970s and 1980s, overexploitation of this resource caused the population to decrease drastically.This study is a report on the population status of the giant Mexican limpet S. mexicana on the Mexican Pacific coast. Free divers explored the rocky southern coast of Jalisco, Mexico, for the presence of specimens. A total of 404 limpets were identified at 18 sampling sites. Their density was estimated to be 0.0012 limpets/m2 with a catch per unit effort of 7.6 limpets/dive hour. Limpet sizes ranged from 5.0 to 23.3 cm in length and from 3.8 to 20.7 cm in width, with a mean shell length of 13.4 cm.Currently, S. mexicana is under special protection by Mexican laws. However, this species is not listed as endangered by any international wildlife protection and conservation group. This may be due to the lack of information on this species' population dynamics over time in the Mexican Pacific and the lack of interest in this mollusc since it is a non‐charismatic species. [ABSTRACT FROM AUTHOR]

Benthic primary producers in tropical reef ecosystems can alter biogeochemical cycling and microbial processes in the surrounding seawater. In order to quantify these influences, we measured rates of photosynthesis, respiration, and dissolved organic carbon (DOC) exudate release by the dominant benthic primary producers (calcifying and non-calcifying macroalgae, turf-algae and corals) on reefs of Mo'orea French Polynesia. Subsequently, we examined planktonic and benthic microbial community response to these dissolved exudates by measuring bacterial growth rates and oxygen and DOC fluxes in dark and daylight incubation experiments. All benthic primary producers exuded significant quantities of DOC (roughly 10% of their daily fixed carbon) into the surrounding water over a diurnal cycle. The microbial community responses were dependent upon the source of the exudates and whether the inoculum of microbes included planktonic or planktonic plus benthic communities. The planktonic and benthic microbial communities in the unamended control treatments exhibited opposing influences on DO concentration where respiration dominated in treatments comprised solely of plankton and autotrophy dominated in treatments with benthic plus plankon microbial communities. Coral exudates (and associated inorganic nutrients) caused a shift towards a net autotrophic microbial metabolism by increasing the net production of oxygen by the benthic and decreasing the net consumption of oxygen by the planktonic microbial community. In contrast, the addition of algal exudates decreased the net primary production by the benthic communities and increased the net consumption of oxygen by the planktonic microbial community thereby resulting in a shift towards net heterotrophic community metabolism. When scaled up to the reef habitat, exudate-induced effects on microbial respiration did not outweigh the high oxygen production rates of benthic algae, such that reef areas dominated with benthic primary producers were always estimated to be net autotrophic. However, estimates of microbial consumption of DOC at the reef scale surpassed the DOC exudation rates suggesting net consumption of DOC at the reef-scale. In situ mesocosm experiments using custom-made benthic chambers placed over different types of benthic communities exhibited identical trends to those found in incubation experiments. Here we provide the first comprehensive dataset examining direct primary producer-induced, and indirect microbially mediated alterations of elemental cycling in both benthic and planktonic reef environments over diurnal cycles. Our results highlight the variability of the influence of different benthic primary producers on microbial metabolism in reef ecosystems and the potential implications for energy transfer to higher trophic levels during shifts from coral to algal dominance on reefs.

Mugil curema is a teleost fish of economic importance that shows wide phenotypic variability in the coasts of Mexico. Intraspecific morphological variability might replicate either genetic dissimilarity between groups or environmental conditions according to phenotypic plasticity. Fish scales shape was used to discriminate location variants, genetic structure obtained by microsatellite markers, and marine ecoregions of Mexico. The present study uses landmarks and geometric morphometric statistical approaches to address the specific question: if and how fish scale shape varies with genetic structure or with marine ecoregions. This is assessed using seven landmarks by scale, the coordinates of which were subjected to a generalized Procrustes analysis, followed by a principal components analysis and quadratic discriminant analysis with cross-validation analysis on shape. Also, the significance of classifications was assessed by multivariate analysis of covariance (MANCOVA). The proportion of total shape variance explained by total length and by centroid size was 3.8 and 3.0%, respectively. Therefore, only shape (without size) was used for the analysis. MANCOVA was significant in all cases, with locations, genetic structure, and marine ecoregions. The cross-validated discriminant analysis by location correctly classified 42.2%, whereas with the genetic structure prearrangement and marine ecoregions, the identification rates were 58.3 and 57.0%, respectively. It was surprising that, as the same as in the genetic structure (microsatellite analysis), San Antonio Bay, Texas formed a group with Sabancuy, Campeche, Celestun, and Sisal, Yucatan (the Caribbean locations). Likewise, Huave Lagoon System, Oaxaca, located in the Pacific coast is more similar to the Caribbean sites unlike the other locations from the Pacific area, which are similar results depicted with microsatellite analysis. On the other hand, using the marine ecoregions arrangement, the findings indicate that the Mexican Tropical Pacific and the Chiapas-Nicaragua marine ecoregions were very different as opposed to the two marine ecoregions from the Gulf of Mexico more similar in fish scale shape. The Mexican Tropical Pacific ecoregions show more identification rate (80.4%), whereas the rest of marine ecoregions discriminate less than 53.3%. Possibly, hydrographic features as currents or upwellings circumscribe boundaries between marine ecoregions, and this could produce inherent genetic structure.

Marine resources are integral to the subsistence of coastal populations in Oceania and have been since the islands were first settled. While items of fishing gear, most notably fishhooks, are found throughout the Pacific, they are not as common as one might think. Fishhooks are in fact noticeably uncommon in the Central Pacific, for example. Consequently, the various types of analyses of fishhook morphology, particularly the types of line attachment devices, that have been carried out on East Polynesian assemblages have not been possible for West Polynesian sites. Using a large collection of fishhooks from three sites on Ofu and Olosega islands in the Manu'a Group of American Samoa, we present a detailed analysis of a large combined assemblage and compare the data collected to those from other islands and island groups in the region. We show that the hooks reflect exploitation emphasising inshore environments, and that angling as a fish capture method is likely to vary in intensity based on local environmental variability. Moreover, we illustrate how these fishhooks constitute a means of assessing both early cultural contacts and cultural variability in the Central Pacific. [ABSTRACT FROM AUTHOR]

Abstract Despite strong anisotropy seen in analysis of seismic data from the NoMelt experiment in 70 Ma Pacific seafloor, a previous analysis of coincident magnetotelluric (MT) data showed no evidence for anisotropy in the electrical conductivity structure of either lithosphere or asthenosphere. We revisit the MT data and use 1D anisotropic models of the lithosphere to demonstrate the limits of acceptable anisotropy within the data. We construct 1D models by varying the thickness and the degree of anisotropy within the lithosphere and conduct a series of tests to investigate what types of electrical anisotropy are compatible with the data. We find that electrical anisotropy is possible in a sheared and/or hydrous mantle within the lower lithosphere (60–90 km depth). The data are not compatible with pervasive electrical anisotropy in the crust. Causes of anisotropy within the highly resistive upper and mid-lithosphere, as seen seismically, are not expected to cause measurable impacts on MT response.

Archaea is a poorly studied domain associated with sponges. Many questions that have been addressed for bacteria still remain largely unknown for archaea. In this study, we analyzed the archaeal communities of 17 tropical sponge species from Nha Trang Bay (Vietnam) using archaea specific primers. We recorded patterns of diversity and spatial stability of these microbial communities and compared the results obtained with the bacterial communities, already reported in our previous study. In our study species, Shannon diversity was always lower for archaeal than for bacterial communities. The differences in alpha diversity as well as the presence of indicator phyla reported for the bacterial domain in High Microbial Abundance (HMA) and Low Microbial Abundance (LMA) could not be confirmed for the archaeal communities. Host identity was the main factor structuring the archaeal assemblages. Sponge archaea core was formed by few but very abundant ZOTUs, which contribute with a high proportion to the relative archaea abundance. The inclusion of the obtained sequences into phylogenetic trees allowed finding out whether or not they belonged to the so-called sponge clusters (SC). Our results showed that most of the Thaumarchaeota and Euryarchaeota sequences were more closely related to environmental samples than to SC, suggesting that they might be acquired from the seawater, which need to be verified. However, representatives of Woesarchaeota, which were major members of the archaea microbiome of two sponge species, formed a monophyletic tree, distantly related to any known environmental sequence.

The abyssal demosponge Plenaster craigi inhabits the Clarion‐Clipperton Zone (CCZ) in the northeast Pacific, a region with abundant seafloor polymetallic nodules with potential mining interest. Since P. craigi is a very abundant encrusting sponge on nodules, understanding its genetic diversity and connectivity could provide important insights into extinction risks and design of marine protected areas. Our main aim was to assess the effectiveness of the Area of Particular Environmental Interest 6 (APEI‐6) as a potential genetic reservoir for three adjacent mining exploration contract areas (UK‐1A, UK‐1B and OMS‐1A). As in many other sponges, COI showed extremely low variability even for samples ~900 km apart. Conversely, the 168 individuals of P. craigi, genotyped for 11 microsatellite markers, provided strong genetic structure at large geographical scales not explained by isolation by distance (IBD). Interestingly, we detected molecular affinities between samples from APEI‐6 and UK‐1A, despite being separated ~800 km. Although our migration analysis inferred very little progeny dispersal of individuals between areas, the major differentiation of OMS‐1A from the other areas might be explained by the occurrence of predominantly northeasterly transport predicted by the HYCOM hydrodynamic model. Our study suggests that although APEI‐6 does serve a conservation role, with species connectivity to the exploration areas, it is on its own inadequate as a propagule source for P. craigi for the entire eastern portion of the CCZ. Our new data suggest that an APEI located to the east and/or the south of the UK‐1, OMS‐1, BGR, TOML and NORI areas would be highly valuable. [ABSTRACT FROM AUTHOR]

This article uses comparative linguistic data to arrive at some generalizations about the place naming practices of the early inhabitants of the Central Pacific (Fiji, Rotuma, and Polynesia) who are believed to have arrived there some three thousand years ago. In particular it focuses on a pair of suffixes,-(C)a and-(C)aga, that had similar functions of nominalization and were therefore used quite extensively in various types of derivation, including place naming. Many place names so formed are indicators of the environment that prevailed when the place was named, so have great potential value in the reconstruction of prehistory. [ABSTRACT FROM PUBLISHER]

Despite strong anisotropy seen in analysis of seismic data from the NoMelt experiment in 70 Ma Pacific seafloor, a previous analysis of coincident magnetotelluric (MT) data showed no evidence for anisotropy in the electrical conductivity structure of either lithosphere or asthenosphere. We revisit the MT data and use 1D anisotropic models of the lithosphere to demonstrate the limits of acceptable anisotropy within the data. We construct 1D models by varying the thickness and the degree of anisotropy within the lithosphere and conduct a series of tests to investigate what types of electrical anisotropy are compatible with the data. We find that electrical anisotropy is possible in a sheared and/or hydrous mantle within the lower lithosphere (60-90 km depth). The data are not compatible with pervasive electrical anisotropy in the crust. Causes of anisotropy within the highly resistive upper and mid-lithosphere, as seen seismically, are not expected to cause measurable impacts on MT response. [ABSTRACT FROM AUTHOR]

ABSTRACT In order to clearly classify El Niño-Southern Oscillation ( ENSO) events into eastern Pacific ( EP) and central Pacific ( CP) types, we develop two new indices defined as pattern correlation coefficients ( PCCs) between monthly sea surface temperature ( SST) anomalies ( SSTAs) and first two leading empirical orthogonal function modes of tropical Pacific (20°S-20°N, 110°E-70°W) SSTAs. These new indices not only show close relationships with ENSO indices derived from several previous methods, but also demonstrate reasonable abilities to distinguish between two types of ENSO event. The major characteristic features of the EP-type and CP-type ENSO forcings are well captured from SST responses regressed onto each new index. Furthermore, the monthly frequencies of occurrences derived from two indices are quite similar to variation patterns of phase-locking behaviours of two types of ENSO event. [ABSTRACT FROM AUTHOR]

Para comprender las interacciones tróficas en un ecosistema, es imprescindible conocer bien la composición y superposición de las dietas de las especies que coexisten en un mismo hábitat y presentan una morfología general muy similar. Se analizaron los contenidos estomacales de 397 ejemplares de cuatro especies de Diplectrum, capturados con redes camaroneras frente a las costas de Jalisco y Colima, México. D. eumelum consumió principalmente peces del orden Pleuronectiformes, seguido por camarones del género Metapenaeopsis y estomatópodos. D. euryplectrum registró en su contenido estomacal, estomatópodos (Squilla mantoidea), seguido por camarones y braquiuros. D. labarum consumió crustáceos, moluscos y peces. El estomatópodo Eurysquilla veleronis registró un alto porcentaje, seguido por camarones (principalmente Solenocera florea) y braquiuros, así como el calamar dardo Lolliguncula diomedae. Los peces (género Ophidion principalmente) constituyeron un componente importante de la dieta de esta especie. En la dieta de D. rostrum se identificaron crustáceos, moluscos, poliquetos y peces. El calamar dardo Lolliguncula diomedae y los peces del género Ophidion tuvieron una alta representación. Se observaron diferencias significativas entre los índices de amplitud de dietas de las especies analizadas. El número de entidades consumidas disminuyó desde 16 en D. euryplectrum hasta seis en D. eumelum. El valor medio de superposición (0.247) no resultó significativamente diferente (p=0.118) del esperado para un modelo nulo (0.174). La varianza observada de los índices de superposición (0.071) fue significativamente mayor (V=0.025, p=0.0004) que el valor medio obtenido en la simulación basada en un modelo nulo.Analysis of diet composition and overlap in four species of the genus Diplectrum (Perciformes: Serranidae) in the Mexican Central Pacific. The information of trophic interactions among species is essential to understand ecosystem function. To assess this in four Diplectrum species, we analyzed the stomach contents of 397 individuals caught using shrimp trawling nets off the coasts of Jalisco and Colima, Mexico. Main food component of D. eumelum were fish of the Order Pleuronectiformes, followed by shrimps (Metapenaeopsis spp). D. euryplectrum feeds mainly on crustaceans, with stomatopods (Squilla mantoidea) as main food items followed by shrimps and brachyurans. Fish and polychaetes had a low representation in the diet of this species. D. labarum feeds mainly on crustaceans, mollusks and fish. The stomatopod Eurysquilla veleronis contributed to with a high diet percentage by weight, followed by shrimps (mostly Solenocera florae) and brachyurans, as well as the squid Lolliguncula diomedae. Fishes (Ophidion spp.) were also an important component of the diet of this species. The most common preys of D. rostrum were crustaceans, mollusks, polychaetes and fish. The squid Lolliguncula diomedae and fishes of genus Ophidion were also well represented in the diet. Diet breadth index yielded significant differences between species. The number of diet items varied from 16 in D. euryplectrum to 6 in D. eumelum. The average value of overlap (0.247) was not significantly different (p=0.118) from the expected one for a null model (0.174). The observed variance of the overlap index (0.071) was significantly higher (V=0.025, p=0.0004) than the value expected for a null model. Rev. Biol. Trop. 58 (4): 1189-1198. Epub 2010 December 01.

Sharks are considered to play important roles in structuring marine ecosystems, consequently understanding their trophic ecology and interactions with other marine predators is required. In the central Pacific Ocean, whether the trophic roles of pelagic sharks are complementary or redundant to large teleost predators remains unclear. In this study, stable carbon and nitrogen isotope analysis were used to examine the isotopic niche overlap of eight pelagic shark species and six pelagic teleost predators, including tuna and billfish. Large intra-specific variation and minimal inter-specific variation in both δ 15 N and δ 13 C values were observed among sharks and teleosts. Moreover, there was a high degree of trophic overlap among pelagic shark and teleost species, with the exception of the blue shark, the δ 13 C values of which indicated a much longer foraging time in the purely pelagic waters. Moreover, although the stable isotopic data suggested that the pelagic sharks in the study area share similar prey and habitats with other pelagic predators, such as tuna and billfish, blue sharks and shortfin mako sharks did not show isotopic overlap with these predators. These data highlight the diverse roles among pelagic sharks, supporting previous findings that this species complex is not trophically redundant; but further studies on the diet and fine-scale habitat used are required to verify this hypothesis. [ABSTRACT FROM AUTHOR]

The Line Islands Ridge (LIR), located south of the Hawaiian Islands between 7°N and 1°S, is one of the few large central Pacific regions shallower than the regional carbonate compensation depth. Thick sequences of carbonate sediments have accumulated around the LIR despite it being located in the sediment-starved central tropical Pacific. The LIR is an important source of carbonates to the surrounding region and deposition around the LIR has expanded the equatorial Pacific carbonate sediment tongue by about 5% of its total area. Furthermore, sediments on the ridge are potentially important paleoceanographic archives. A recent survey at the crest of the LIR finds evidence for high current activity, significant erosion, but overall net sediment deposition. Currents are strong enough to form sediment waves and lee drifts in the Palmyra Basin, at the northern terminus of the LIR. Sediments along the LIR are pelagic foraminiferal sands that are easily eroded and flow out into the surrounding abyssal plain in active submarine channel systems. As channels migrate, pelagic sediments fill in the abandoned channel arms. Despite significant sediment losses from the top of the ridge, 1.3 km of sediment has accumulated in the upper Palmyra Basin over basement formed 68 to 85 million years ago (Ma). Late Neogene erosion may be more extensive than earlier erosion cycles, in response to reduced sediment production as the Palmyra Basin exited the high productivity equatorial latitudes. Sediments with good stratigraphic order needed for paleoceanographic study are limited in this dynamic sedimentary environment, but can be found with proper survey. [ABSTRACT FROM AUTHOR]

The white mullet, Mugil curema , is a commercially important species in coastal areas, with a large phenotypic variability and genetic dissimilarity among populations throughout its distribution. For management purposes it is important to determine whether the morphological variability reflects the genetic differences among groups. This study evaluates whether the genetic differentiation in Mugil curema is reflected in the otolith shape on a large geographic scale in the Neotropical Atlantic and the Mexican Pacific. We analyzed the COI (Cytochrome Oxidase I) gene polymorphism as a marker and followed the otolith contour-based Fourier analysis as a morphometric method. Seven locations were studied, four in coastal lagoons of the Gulf of Mexico, one in the Mexican Pacific, one in the Caribbean Sea at Nueva Esparta, Venezuela and one in San Antonio Lagoon, Brazil. The genetic divergence accounted by the COI and the morphological differentiation in M. curema otoliths did not, in general, present cross-scale patterns, and the variability of otolith shapes was not reflected in the mitochondrial genetic variability. Other molecular methods could potentially reveal genetic differences. In particular, the variability in otolith shape among the Gulf of Mexico individuals may indicate that local divergences are accumulated in the otoliths, reflecting a possible interaction effect between local and regional drivers that is not evidenced at the genetic level. • It is the first work in the Gulf of Mexico that compares the otolith morpho and genetic diversity of Mugil curema. • We show evidence of a genetic cluster for the species in the Atlantic Ocean. • The justification of genetic and morphometrics results is supported by coastal circulation. [ABSTRACT FROM AUTHOR]

Benthic primary producers in tropical reef ecosystems can alter biogeochemical cycling and microbial processes in the surrounding seawater. In order to quantify these influences, we measured rates of photosynthesis, respiration, and dissolved organic carbon (DOC) exudate release by the dominant benthic primary producers (calcifying and non-calcifying macroalgae, turf-algae and corals) on reefs of Mo‘orea French Polynesia. Subsequently, we examined planktonic and benthic microbial community response to these dissolved exudates by measuring bacterial growth rates and oxygen and DOC fluxes in dark and daylight incubation experiments. All benthic primary producers exuded significant quantities of DOC (roughly 10% of their daily fixed carbon) into the surrounding water over a diurnal cycle. The microbial community responses were dependent upon the source of the exudates and whether the inoculum of microbes included planktonic or planktonic plus benthic communities. The planktonic and benthic microbial communities in the unamended control treatments exhibited opposing influences on DO concentration where respiration dominated in treatments comprised solely of plankton and autotrophy dominated in treatments with benthic plus plankon microbial communities. Coral exudates (and associated inorganic nutrients) caused a shift towards a net autotrophic microbial metabolism by increasing the net production of oxygen by the benthic and decreasing the net consumption of oxygen by the planktonic microbial community. In contrast, the addition of algal exudates decreased the net primary production by the benthic communities and increased the net consumption of oxygen by the planktonic microbial community thereby resulting in a shift towards net heterotrophic community metabolism. When scaled up to the reef habitat, exudate-induced effects on microbial respiration did not outweigh the high oxygen production rates of benthic algae, such that reef areas dominated with benthic primary producers were always estimated to be net autotrophic. However, estimates of microbial consumption of DOC at the reef scale surpassed the DOC exudation rates suggesting net consumption of DOC at the reef-scale. In situ mesocosm experiments using custom-made benthic chambers placed over different types of benthic communities exhibited identical trends to those found in incubation experiments. Here we provide the first comprehensive dataset examining direct primary producer-induced, and indirect microbially mediated alterations of elemental cycling in both benthic and planktonic reef environments over diurnal cycles. Our results highlight the variability of the influence of different benthic primary producers on microbial metabolism in reef ecosystems and the potential implications for energy transfer to higher trophic levels during shifts from coral to algal dominance on reefs.

The giant clam subfamily Tridacninae (family Cardiidae) is an important group of bivalve molluscs found throughout the Red Sea and Indo-Pacific, from East Africa to the Eastern Pacific biogeographic region. TheTridacnagenus is currently revised with numerous cryptic species identified with molecular markers. NewTridacnarecords from the fringe of the known distribution areas are extremely useful to identify genetically unique species, geographic ranges, and to examine processes associated with species differentiation. WhileTridacna maximais abundant in French Polynesia (Central South Pacific Ocean) the larger fluted giant clamTridacna squamosawas formerly reported only in the Austral Islands in the south. Following a recent survey that spanned 23 islands and atolls of the Society, Tuamotu and Gambier Archipelagos, the presence ofT. squamosabetween the Cook Islands and Pitcairn Islands is confirmed using both morphological and molecular information, suggesting a relic distribution across the Central Pacific Ocean.Tridacna squamosais rare, but present throughout Tuamotu and Gambier. However, it remained undetected from the Society Islands, probably due to historical over-fishing. This species is valued by local inhabitants, and is sought after mainly as gifts and also for a limited local shell trade. The rarity ofT. squamosamay call for conservation measures in the near future. [ABSTRACT FROM AUTHOR]

The central Pacific (CP) zonal wind divergence and convergence indices are defined, and the forming mechanism of CP El Niño (La Niña) events is discussed preliminarily. The results show that the divergence and convergence of the zonal wind anomaly (ZWA) are the key process in the forming of CP El Niño (La Niña) events. A correlation analysis between the central Pacific zonal wind divergence and convergence indices and central Pacific El Niño indices indicates that there is a remarkable lag correlation between them. The central Pacific zonal wind divergence and convergence indices can be used to predict the CP events. Based on these results, a linear regression equation is obtained to predict the CP El Niño (La Niña) events 5 months ahead. [ABSTRACT FROM AUTHOR]

Aim To explore the spatial and temporal genetic structure of four tropical hermit crabs in the genus Calcinus with varying habitat use in order to test for impacts of sea-level change and demography in shaping contemporary population structure and to understand how this structure relates to the process of speciation in the genus. Location Central Pacific. Methods We sequenced 586 bp of the cytochrome c oxidase subunit I gene ( COI) ( n = 702) and analysed the data for population differentiation and demographic changes. We complemented the sequences with abundance surveys of targeted species and modelled potential habitat availability in response to sea-level change. Results Sequence data revealed high haplotype diversity ( h = 0.685-0.983) and low nucleotide diversity (π = 0.002-0.018) for all species. There was little population differentiation and extensive geographical haplotype sharing within all species, despite dramatic shifts in the abundance of species among locations, which appear to result from ecological interactions rather than limits to contemporary larval dispersal. Population expansion occurred most recently in the subtidal species Calcinus haigae (30-70 ka), whereas the intertidal species showed earlier expansions: Calcinus seurati: 110-140 ka, and Calcinus laevimanus: 220-250 ka. Differences in timing can be linked to the prediction that subtidal habitat area is strongly affected by changing sea level, while intertidal habitat area is affected less strongly. Interestingly, unlike the West Pacific, habitat in the Central Pacific remains relatively equidistant. Main conclusions Habitat availability during sea-level fluctuations, rather than dispersal limitation per se, appears to be a potential force shaping the population genetic patterns of subtidal species, and perhaps speciation of tropical Calcinus hermit crabs. Insofar as this represents a general pattern, historical sea-level change may play a role in structuring Central Pacific reef species through alteration of habitat availability rather than isolation and vicariance. [ABSTRACT FROM AUTHOR]

The expanse of deep water between the central Pacific islands and the continental shelf of the Eastern Tropical Pacific is regarded as the world's most potent marine biogeographic barrier. During recurrent climatic fluctuations ( ENSO, El Niño Southern Oscillation), however, changes in water temperature and the speed and direction of currents become favourable for trans-oceanic dispersal of larvae from central Pacific to marginal eastern Pacific reefs. Here, we investigate the population connectivity of the reef-building coral Porites lobata across the Eastern Pacific Barrier ( EPB). Patterns of recent gene flow in samples ( n = 1173) from the central Pacific and the Eastern Tropical Pacific ( ETP) were analysed with 12 microsatellite loci. Results indicated that P. lobata from the ETP are strongly isolated from those in the central Pacific and Hawaii ( [ABSTRACT FROM AUTHOR]

The Phoenix Islands (Republic of Kiribati, 172-170°W and 2.5-5°S) experience intra- and inter-annual sea surface temperature variability of ≈2°C and have few local anthropogenic impacts. From July 2002, a thermal stress event occurred, which peaked at 21 Degree Heating Weeks (DHW) in January 2003 and persisted for 4 years. Such thermal stress was greater than any thermal event reported in the coral reef literature. Reef surveys were conducted in July 2000, June 2002, and May 2005, for six of the eight islands. Sampling was stratified by exposure (windward, leeward, and lagoon) and depth (5, 10, 15, and 25 m). The thermal stress event caused mass coral mortality, and coral cover declined by approximately 60% between 2002 and 2005. However, mortality varied among sites (12-100%) and among islands (42-79%) and varied in accordance with the presence of a lagoon, island size, and windward vs. leeward exposure. Leeward reefs experienced the highest and most consistent decline in coral cover. Island size and the presence of a lagoon showed positive correlations with coral mortality, most likely because of the longer water residence time enhancing heating. Windward reefs showed cooler conditions than leeward reefs. Recently dead corals were observed at depths >35 m on windward and >45 m on leeward reefs. Between-island variation in temperature had no effect on between-island variation in coral mortality. Mortality levels reported here were comparable to those reported for the most extreme thermal stress events of 9-10 DHW in other regions. These results highlight the high degree of acclimation and/or adaptation of the corals in the Phoenix Islands to their local temperature regime, and their consequent vulnerability to anomalous events. Moreover, the results suggest the need to adjust thermal stress calculations to reflect local temperature variation. [ABSTRACT FROM AUTHOR]

Abstract: A management proposal aims to partly remove a WWII military causeway at Palmyra Atoll to improve lagoon water circulation and alleviate sedimentation stress on the southeast backreef, an area of high coral cover and diversity. This action could result in a shift in sedimentation across reef sites. To provide management advice, we quantified the proximate environmental factors driving scleractinian coral cover and community patterns at Palmyra. The proportion of fine sedimentation was the optimal predictor of coral cover and changes in community structure, explaining 23.7% and 24.7% of the variation between sites, respectively. Scleractinian coral cover was negatively correlated with increases in fine sedimentation. Removing the causeway could negatively affect the Montipora corals that dominate the western reef terrace, as this genus was negatively correlated with levels of fine sedimentation. The tolerance limits of corals, and sediment re-distribution patterns, should be determined prior to complete removal of the causeway. [Copyright &y& Elsevier]

Abstract: The geoid low over French Polynesia has been previously interpreted as the signature of an upper mantle upwelling associated with a low-viscosity zone located immediately below the lithosphere. We propose here an alternative explanation using new high-quality satellite gravity data and fluid mechanics constraints. We thus discuss the origin of the high concentration of hotspots in the Central Pacific, which is still debated. Satellite gravity data from the GRACE mission analyzed with wavelets allow us to better characterize the geoid low on French Polynesia and the large-scale positive geoid anomaly 600km east of the Line Islands chain. We show that the geoid anomalies are consistent with thermochemical oscillating domes and we bring constraints on their density contrast and their upper limit depth under this hypothesis. The Central Pacific mantle would contain two thermochemical instabilities at different stages of their development: a rising dome (lighter) extending approximately from the CMB up to the transition zone beneath the South Pacific Superswell, toped by secondary plumes that generate short-lived hot spot chains, and a sinking dome (denser) in the lower mantle beneath the area located 600km east of the Line Islands chain. Plate reconstructions further show that the latter could also have generated the Southern Line Islands 35M.y. ago and Shatsky Rise 140M.y. ago when it was in its ascending phase, while the South Pacific dome probably created Darwin Rise 100M.y. ago in a same type of event. [Copyright &y& Elsevier]

The article discusses a study on disease dynamics under near-pristine, intact conditions at the Palmyra Atoll in central Pacific. The study found that overall disease prevalence across the atoll was low at 0.33% but higher on the shallower backreef at 0.88% and reef terrace at 0.80% than on the deeper forereef at 0.09%. It was also found that growth anomalies (GAs) were the most encountered lesions in scleractinian species in the genera Asteopora at 2.12%, Acropora at 1.3%, and Montipora at 0.98%. The study suggested more sophisticated analyses to be conducted to tease apart the possible inter-correlated proximate drivers of disease occurrence on remote, near-pristine reefs.

The anthropogenic plutonium isotopes are important geochemical tracers for environmental studies. The distributions and sources of the Pu isotopes in water column or sediments of the North Pacific have been intensively studied. However, knowledge on the distribution of Pu isotopes in sediments of the Central Pacific, when available, is limited. To study the composition of Pu isotopes in the ocean, thus to identify the sources of radioactive pollution, sediment core samples were collected in the Central Pacific by R/V Hakuho Maru in the KH-04-5 cruise. The activity concentrations of Pu and the Pu/Pu atom ratio were determined using a sector-field inductively coupled mass spectrometry (SF-ICP-MS) combined with a high efficiency sample introduction system (APEX-Q). Possible sources and sedimentation behavior of Pu isotopes are discussed. [ABSTRACT FROM AUTHOR]

The indirect, ecosystem-level consequences of ocean fishing, and particularly the mechanisms driving them, are poorly understood. Most studies focus on density-mediated trophic cascades, where removal of predators alternately causes increases and decreases in abundances of lower trophic levels. However, cascades could also be driven by where and when prey forage rather than solely by prey abundance. Over a large gradient of fishing intensity in the central Pacific's remote northern. Line Islands, including a nearly pristine, baseline coral reef system, we found that changes in predation risk elicit strong behavioral responses in foraging patterns across multiple prey fish species These responses were observed as a function of both short-term ("acute") risk and longer-term ("chronic") risk, as well as when prey were exposed to model predators to isolate the effect of perceived predation risk from other potentially confounding factors. Compared to numerical prey responses, antipredator. behavioral responses such as these can potentially have far greater net impacts (by occurring over entire assemblages) and operate over shorter temporal scaIe (with potentially instantaneous response times) in transmitting top-down effects. A rich body of literature exists on both the direct effects of human removal of predators from ecosystems and predators' effects on prey behavior. Our results draw together these lines of research and provide the first empirical evidence that large-scale human removal of predators from a natural ecosystem indirectly alters prey behavior. These behavioral changes may, in turn, drive previously unsuspected alterations in reef food webs. [ABSTRACT FROM AUTHOR]

Abstract: Studies in epipelagic waters report higher heterotrophic microbial biomass in the productive high latitudes than in the oligotrophic low latitudes; however, biogeographical data are scarce in the deep ocean. To examine the hypothesis that the observed latitudinal differences in heterotrophic microbial biomass in the epipelagic zone also occur at depth, abundance and biomass of heterotrophic prokaryotes, nanoflagellates (HNF), and ciliates were determined at depths of 5–5000m in the central Pacific between August and September of 2005. Heterotrophic microbial biomass increased from the tropical to the subarctic region over the full water column, with latitudinal differences in prokaryotic biomass increasing from 2.3-fold in the epipelagic zone to 4.4-fold in the bathypelagic zone. However, the latitudinal difference in HNF and ciliate biomass decreased with depth. In the mesopelagic zone, the vertical attenuation rate of prokaryotic abundance, which was calculated as the linear regression slope of log-log plot of abundance versus depth, ranged from –0.55 to –1.26 and was more pronounced (steeper slope) in the lower latitudes. In contrast, the vertical attenuation rate of HNF in the mesopelagic zone (–1.06 to –1.27) did not differ with latitude. In the subarctic, the attenuation rate of HNF was 1.7 times steeper than for prokaryotes. These results suggest the accumulation of prokaryotes in the deep subarctic Pacific, possibly due to low grazing pressure. Although the vertical attenuation rate of ciliates was steepest in the bathypelagic zone, HNF abundance did not further decrease at depths below 1000m, except for at 2000m where HNF was lowest across the study area. Ciliate abundance ranged 0.3–0.8 cells l–1 at 4000m, and were below the detection limit (<0.1 cells l –1) at 5000m. To our knowledge, this study presents the first data for ciliates below 2000m. [Copyright &y& Elsevier]

The marine flora of Wake Atoll is phytogeographically interesting because the atoll is a small (6.5 km2) isolated coral reef structure located in the central Pacific between the north-western Hawaiian Islands and the Marshall Islands. Eighty-one of the 103 species of subtidal marine benthic algae collected in October 2005 and April–May 2007 during two NOAA cruises to Wake Atoll represent new records for the atoll. Previously published collections include five species collected in December 1841 during the US Exploring Expedition, 35 additional species representing collections made in June 1998 by US Fish and Wildlife personnel, and incidental specimens collected by various biologists and deposited in the Herbarium Pacificum of the Bishop Museum, Honolulu. The 121 species of marine benthic algae now documented from Wake Atoll contain components from the Hawaiian Islands and Marshall Islands, but show a closer resemblance to those of the Hawaiian Archipelago. [ABSTRACT FROM AUTHOR]

The Cocos-Nazca spreading center is one of the few examples of the formation of a spreading center by splitting of oceanic lithosphere. It was created when the Farallon plate broke up in the early Miocene following the collision of the Pacific-Farallon spreading center with the North American continent. Much of the ancient Farallon plate corresponding to the area of opening is lost to subduction beneath Central America and South America, but new data from the conjugate area on the Pacific plate allow the first detailed reconstruction of the break-up process. The opening began after chron 7 (25 Ma) at a location of focused crustal extension caused by overlapping spreading centers that had evolved in response to a slight reorientation of a Pacific-Farallon ridge segment. Beginning at chron 6B (22.7 Ma), eastward progressing seafloor spreading started along an axis that most likely migrated toward the region of weak lithosphere created by the Galapagos hotspot. By chron 6 (19.5 Ma), plate splitting from the spreading center to the trench was complete, allowing the fully detached Cocos and Nazca plates to move independently. This kinematic change resulted in a significant ridge jump of the newly established Pacific-Nazca spreading center, a change in plate motion direction of the Nazca plate by 20° clockwise, and a large increase in Pacific-Cocos plate velocity in the middle Miocene. [ABSTRACT FROM AUTHOR]

Up to now, accurate determination of the growth age and hiatuses of the Co-rich crust is still a difficult work, which constrains the researches on the genesis, growth process, controlling factors, regional tectonics, paleo-oceanographic background, etc. of the Co-rich crust. This paper describes our work in determining the initial growth age of the Co-rich crust to be of the late Cretaceous Campanian Stage (about 75–80 Ma), by selecting the Co-rich crust with clear multi-layer structures in a central Pacific seamount for layer-by-layer sample analysis and using a number of chronological methods, such as Co flux dating, dating by correlation with 187Os/188Os evolution curves of seawater, and stratigraphic division by calcareous nannofossils. We have also discovered growth hiatuses with different time intervals in the early Paleocene, middle Eocene, late Eocene and early-middle Miocene, respectively. These results have provided an important age background for further researches on the Co-rich crust growth process and the paleo-oceanographic environment evolution thereby revealed in the said region. [ABSTRACT FROM AUTHOR]

Abstract: The possible sources of pre-anthropogenic Pb contributed to the world''s oceans have been the focus of considerable study. The role of eolian dust versus riverine inputs has been of particular interest. With better calibration of isotopic records from central Pacific ferromanganese crusts using Os isotope stratigraphy it now appears that deep water Pb isotopic compositions were effectively homogeneous over a distance of 5000 km for the past 80 Myr. The composition shifted slightly from high 206Pb/204Pb ratios in the range of 18.87±0.02 before 65 Ma to lower values of 18.62±0.02 by 45 Ma and then gradually increased again very slightly to the present day ratio of 18.67±0.02. The regional homogeneity provides evidence of a dominant well-mixed atmospheric source the most likely candidate for which is volcanic aerosols contributed either directly or as soluble condensates on eolian dust. The slight shift in Pb isotope composition of deep waters in the central Pacific between 65 and 45 Ma may be the result of a regional- or perhaps global-scale change in the sources of volcanic exhalations and volcanic activity caused by an increase in the importance of melting and assimilation of older continental crustal components over the Cenozoic. [Copyright &y& Elsevier]

Abstract: Ferromanganese crusts provide records of long term change in ocean circulation and continental weathering. However, calibrating their age prior to 10 Ma has been entirely based on empirical growth rate models using Co concentrations, which have inherently large uncertainties and fail to detect hiatuses and erosional events. We present a new method for dating these crusts by measuring their osmium (Os) isotope record and matching it to the well-known marine Os isotope evolution of the past 80 Ma. The well-characterised crust CD29-2 from the central Pacific, was believed to define a record of paleooceanographic change from 50 Ma. Previous growth rate estimates based on the Co method are consistent with the new Os isotope stratigraphy but the dating was grossly inaccurate due to long hiatuses that are now detectable. The new chronology shows that it in fact started growing prior to 70 Ma in the late Cretaceous and stopped growing or was eroded between 13.5 and 47 Ma. With this new technique it is now possible to exploit the full potential of the oceanographic and climatic records stored in Fe–Mn crusts. [Copyright &y& Elsevier]

187Os/188Os ratios in all sub-layers of the Co-rich ferromanganese crust MP5D17 from Line Seamount in Central Pacific have been systematically determined. The 187Os/188Os values in this crust are highly variable, ranging from 0.4262 to 1.0155. From the bottom to the top, the osmium isotopic ratios of the crust display a regular variation trend, which correlates well with its changes in structure and texture in the vertical profile. In comparison with the evolution curve of Os isotopic composition in seawater over the past 80 Ma, a similar evolution tendency can be found with respect to the Os isotopic composition of the crust in this study, it is preliminarily concluded that the crust MP5D17 began to grow at about 72 Ma, and underwent three growth hiatuses, corresponding to the geological ages of 64, 53 and 37 Ma, respectively. [ABSTRACT FROM AUTHOR]

The trace element composition of young-of-the-year(YOY) juvenile swordfishXiphias gladiussagittal otoliths were analysed as a preliminary test of the value of otolith elemental fingerprints for determining swordfish nursery ground origins in the central Pacific Ocean. A suite of five elements(Mg, Zn, Sr, Ba and Pb) was assayed with isotope dilution ICP-MS; all elemental concentrations were roughly comparable to otoliths of other marine fishes. Multivariate analyses of elemental fingerprints based on Ba and Sr revealed differences between sample sites, and the magnitude of the differences increased with latitudinal separation. With more comprehensive sampling of nursery grounds, it should be possible to identify origin of nursery ground for adult swordfish by analysing the YOY juvenile portion of the sagittal otolith. [ABSTRACT FROM AUTHOR]

Barite (BaSO4) in marine sediments is considered as a proxy of surface ocean productivity and is widely used for paleo-productivity reconstructions. However, direct barite determination is not achieved by currently used methods, which rely on the measurement of total barium by inductively coupled plasma–mass spectrometry (ICP-MS) and instrumental neutron activation analysis (INAA) and correction from the allogenic Ba contribution. We report here on a technique that directly counts individual barite crystals using a scanning electron microscope (SEM) coupled to an energy dispersive spectrometer (EDS) equipped with an automated particle counting and classification (ACC) system. We show that barite–Ba concentrations can be deduced from the abundance, shape and size distributions of barite crystals with current precision and sensitivity as high as ±5 wt.% (2σ confidence limit) and 10 ppm, respectively. This technique, coupled with ICP-MS and INAA techniques for total Ba measurements, was applied to sediment samples from the tropical North Atlantic and the Central North Pacific oceans. Results show that: (1) barite and detrital aluminosilicates are the two main carriers of Ba in the investigated sediments; (2) calculated Ba/Al ratios range from 0.005 to 0.008 with an average value around 0.0066, in close agreement with previously reported values; (3) barite might not be the major source for released barium out of sediments and we suggest instead adsorbed barium as a potential source. [Copyright &y& Elsevier]

Previous studies from PKP(AB–DF) differential travel times at large distances suggest that the central part of the inner core is very anisotropic. These differential times, however, can be affected greatly by strong heterogeneity in the lowermost mantle. Here we examine a unique data set of PKP travel times from global digital and analog stations at near antipodal distances, where the effects of both inner core anisotropy and mantle heterogeneity are the greatest. Our results show that the AB–DF residuals for the polar paths are consistently larger than those of the equatorial paths by over 3–4 standard deviations. We also measured DF and AB absolute times, and found that the DF residuals are negatively correlated with the AB–DF residuals while the AB residuals have a much weaker correlation with the AB–DF residuals. We compare several mantle models with the data. Our results suggest that the mantle structure can explain part of the residuals of the equatorials paths, but cannot explain the polar path anomalies. These results strongly suggest that most of the AB–DF anomalies for the polar paths are likely from the inner core anisotropy and not from mantle heterogeneity. Assuming a uniform cylindrical anisotropy model, the average inner core anisotropy amplitude is about 2.5%. On the other hand, equatorial paths from events in the west Pacific and recorded at South America show a steep azimuthal change in AB–DF times (about 4 s over a 60° azimuthal range). The sharp change is well predicted by existing P and S tomographic models: the azimuthal change occurs as the AB paths sweep across the great slow anomaly in the central Pacific. The high correlation between the P and S velocities suggests that the central Pacific slow anomaly may be of thermal origin. [Copyright &y& Elsevier]

A new anthine fish, Pseudanthias calloura, is described on the basis of three specimens from Palau. The new species differs from other congeners in having a complicated color pattern of the caudal fin and the following characters: moderately forked caudal fin; dorsal fin with 10 spines, the anterior ones being shorter than the rest, and with 16 soft rays; second anal spine shorter than the third; 19 pectoral rays; scales on lateral line 51 (holotype) to 53 (paratypes) in number; tongue without teeth; circumorbital rim with several fleshy projection on posterior part; a row of fine scales occurring asymmetrically behind alternate dorsal spines on both left and right sides; preopercle margin finely serrated; interopercle and subopercle margins smooth. [ABSTRACT FROM AUTHOR]