Ocean Research Articles

How Many Oceans Are There?

How Many Oceans Are There?

Following You: Second Person in Walt Whitman’s “As I Ebb’d with the Ocean of Life”

Following You: Second Person in Walt Whitman’s “As I Ebb’d with the Ocean of Life”

Early 2017 Activity of the Barren Island Volcano:Facts Versus Hype

Barren Island is the northernmost active stratovolcano of the Sunda Volcanic Arc system in the northeastern Indian Ocean. It is the only active volcano in the Indian territory. The arc is a result of subduction of the Indian plate beneath the Burma plate, a sliver of the Eurasian plate. This subduction zone is a southward extension of the Himalayan convergent boundary that takes a turn at the Eastern Syntaxial Bend. Located ~135 km northeast of Port Blair (12°70'N/93°51'E), the Barren Island volcano covers a subaerial area of ~8 km.

Linking Ocean Observation and Fisheries - Relevance to Deep Ocean Living Resources

Systematic ocean observation for real time data collection during the last three decades, development of sensors and tools, and ocean modelling have paved the way for better understanding of the ocean processes and better prediction of coastal hazards like cyclones, tsunami, storm surge, etc., leading to direct societal benefits globally. In particular global ARGO float data have brought in remarkable changes in ocean science studies. This paper discusses about the growing need to link ocean observation to fisheries and futuristic approach about deep ocean marine living resources

Holocene tephra from the Chukchi-Alaskan margin, Arctic Ocean: Implications for sediment chronostratigraphy and volcanic history

Developing chronologies for sediments in the Arctic Ocean and its continental margins is an important but challenging task. Tephrochronology is a promising tool for independent age control for Arctic marine sediments and here we present the results of a cryptotephra study of a Holocene sedimentary record from the Chukchi Sea. Volcanic glass shards were identified and quantified in sediment core HLY0501-01 and geochemically characterized with single-shard electron microprobe and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). This enabled us to reveal a continuous presence of glass shards with identifiable chemical compositions throughout the core. The major input of glasses into the sediments is geochemically fingerprinted to the ∼3.6 ka Aniakchak caldera II eruption (Alaska), which provides an important chronostratigraphic constraint for Holocene marine deposits in the Chukchi-Alaskan region and, potentially, farther away in the western Arctic Ocean. New findings of the Aniakchak II tephra permit a reevaluation of the eruption size and highlight the importance of this tephra as a hemispheric late Holocene marker. Other identified glasses likely originate from the late Pleistocene Dawson and Old Crow tephras while some cannot be correlated to certain eruptions. These are present in most of the analyzed samples, and form a continuous low-concentration background throughout the investigated record. A large proportion of these glasses are likely to have been reworked and brought to the depositional site by currents or other transportation agents, such as sea ice. Overall, our results demonstrate the potential for tephrochronology for improving and developing chronologies for Arctic Ocean marine records, however, at some sites reworking and redistribution of tephra may have a strong impact on the record of primary tephra deposition.

New findings of rare fish species in Indian and Pacific oceans with the description of two new species from the families Gobiidae and Platycephalidae

We provide information about the morphology and new findings of 15 rare fish species from the families Bathyclupeidae, Callionymidae, Champsodontidae, Cottidae, Gobiidae, Lophichthyidae, Melanostomiidae, Moridae, Oneirodidae, Paralepididae, Pegasidae, Platycephalidae, and Uranoscopidae. Two new species are described: Thysanophrys haploblepharis sp. n. (Platycephalidae) from the Western Indian Ocean and Vanderhorstia stegauchenia sp. n. (Gobiidae) from the South China Sea. The new synonymy is established: Cottus dybowskii Hilgendorf, 1879 = Myoxocephalus brandtii.

Influence of the Coastal Upwelling along the Northern Gulf of Guinea on the West Monsoon Flux

This study focused on the influence of the seasonal coastal upwelling north of the Gulf of Guinea (GG) on the West Africa Monsoon (WAM) fluxes during the 1980-2016 period based on the ERA-Interim data from the European Centre for Medium Range Weather Forecasts (ECMWF). The results show that the WAM is responsible of most of the rainfall over West Africa but convective precipitation remains the major component of this rainfall. In coastal area, the convective processes are active during April-June when advection of high moisture quantity from the ocean to the land is established. In July-August, the dry season of the bordering region of the GG coincides with the maximum coastal upwelling, which cools SST and the continental air temperature to values less than 26oC. The presence of this cold air temperature combined with the impoverishment of humidity and reduction of wind counteract the convection and then lead to the decrease of the convective rainfall. This action could be the mechanism by which the north coastal upwelling of the GG influences the flux of the West African Monsoon.

Using Artificial Intelligence to Predict Animal Behaviour in Food Webs

Overfishing of species in the marine life has caused oceans to become deserts at a fast pace. The population of specific species such as Cod and Haddock has reduced over the years. This has affected countries that hugely depend on them as a source of food. This study used Dynamic Bayesian Network (DBN) to predict animal behaviour in a food web. Two independent biomass surveys from the North Sea were used to learn predictive models and test them on the Northern Gulf Ocean. The resulting predictive model is expected to unveil useful information about what affects the population of fishes in the Northern Gulf Ocean. In addition, the predictive model was used to make predictions into the future about the effects of tampering with the population of specific species of fish in the same region. The focus was on the Cod species in the George’s Bank in relationship to species network in their food web. Looking at their biomass states and the effects it has on the hidden dependence when there is a change in their biomass states. Also, the different predictive models were used to evaluate species in the George’s Bank based on their performance. The result from the experiment shows that there is a hidden dependence, which is responsible for the collapse of species (Cod); due to the temperature or salinity of the ocean.

Seasonal pH and carbondioxide level as indicator of vulnerability of fresh and marine aquatic systems to climate change in Nigeria

Rising atmospheric carbon dioxide (CO2) concentrations over the past two centuries have led to greater CO2 uptake by the oceans; raising concern over the current and future effects it may have on world climates. Certain changes are already evident but the impact of these changes on marine and coastal living resources is only poorly understood at this stage, particularly in sub-Saharan Africa. This study assessed seasonal dissolved carbon dioxide and pH of fresh and marine aquatic systems in Nigeria. Dissolved CO2 was non-significantly (p=0.07) higher in freshwater during the wet season (20±7ppm) compared to dry season (15 ± 1ppm), while in the marine system, dissolved CO2 level was significantly (p=0.02) higher (42±6ppm) during the dry season compared to the rainy season (31±5ppm). Mean pH values was significantly higher (p=0.003 and 0.05) in freshwater (6.8±0.8 and 6.9±0.2ppm) relative to marine (6.2±0.2 and 6.5±0.3ppm) during wet and dry seasons, respectively. The pH values were generally at the borderline of the acidic limit of the recommended pH values for aquaculture (6.5-9) during the two seasons. Rising atmospheric carbon dioxide (CO2) concentrations over the past two centuries have led to a greater CO2 uptake by the oceans, acidification and consequently, saturation, thereby affecting the ocean’s continued ability to store CO2. This study therefore provides preliminary information on seasonal changes in CO2 and pH of fresh and marine systems in Nigeria; and their potential impacts on global climate and aquatic ecosystems.Keywords: Acidification, Aquatic system, Carbon dioxide, Climate change, Fresh water, Marine water

Tectonic significance of the cumulate gabbros within Kuluncak Ophiolitic suite (Malatya, SE Turkey) inferred from geochemical data

The Kuluncak (Malatya) ophiolite in the Eastern Tauride, Turkey, consists of mantle tectonites, ultramafic-mafic cumulates, isotropic gabbros, a sheeted dike complex, plagiogranites, and a volcanic complex. The best exposure of the mafic cumulate rocks of the Kuluncak ophiolite is in the Hekimhan region, where they are represented by olivine gabbro and gabbro showing orthocumulate to mesocumulate textures. The cumulus and postcumulus minerals do not show significant zoning. The crystallization order of the cumulates is olivine, plagioclase, clinopyroxene and orthopyroxene. Whole-rock major- and trace-element geochemistry of the mafic cumulate rocks indicates that the primary magma generating the Kuluncak ophiolite is similar in composition to those observed in modern island-arc tectonic settings. Rare earth element (REE) concentrations of the mafic cumulates exhibit depleted light rare earth element (LREE) patterns, with CeN/SmN and CeN/YbN ratios ranging from 0.21 to 0.75 and from 0.17 to 0.66, respectively. The coexistence of anorthite-rich plagioclase (An 73.4-93.7 ), highly magnesian olivine (Fo 65.2-86.9 ), clinopyroxene (Mg# 75-92.1 ), and orthopyroxene (Mg# 77.6-84.3 ) in the cumulate gabbroic rocks is indicative of an intraoceanic subduction setting and suggests that the Kuluncak ophiolite was formed during the Late Cretaceous closure of the Inner Tauride Ocean.

Oceanic primary production and marine water quality assesment around chennai coast - Tamilnadu, India

Oceanic primary production and marine water quality assesment around chennai coast - Tamilnadu, India

Pollen in fossil hyrax dung from Marine Isotope Stages 2 and 3 reveals past environments in Namibia

In view of a scarcity of terrestrial Quaternary pollen records relating to climate change in desert areas, we present new terrestrial sequences from hyrax middens in Namibia. While the few previously available pollen records are mainly Holocene, we present climate time series for Marine Isotope Stages 2 and 3 (MIS 2 and MIS 3). The data are from two sites in central Namibia that are surrounded by desert plains and close to the Namibian escarpment, viz., the Dâures Massif (Brandberg) and 200 km further south, the Mirabib Shelter located in a small inselberg. In the studied material, grass-rich pollen assemblages were more common at Mirabib where the vegetation is desert grassland, than at Brandberg with its mountain vegetation. Hyrax radiocarbon ages range from 21 ka to >50 ka, with inconsistencies in ages near the limit of effective radiocarbon dating. However, correlation of overlapping sequences supports the chronology we present. Despite chronological gaps in the available deposits, pollen assemblages from different middens indicate marked climate cycles, starting with moderately cool dry conditions with grassy karroid vegetation at Mirabib c. 50 ka. After a gap in the record, warmer conditions with savanna woodland are indicated at both Mirabib and Brandberg around 40 ka. Eventually, cool conditions supporting shrubby grassland with wild olives developed at Brandberg during MIS 2, c. 21 ka. Comparison with marine pollen data confirms earlier findings that terrestrial pollen assemblages differ markedly from South Atlantic Ocean marine pollen assemblages of the same age presumably due to mixing of pollen from wide source areas at the marine localities versus the more locally restricted terrestrial pollen sources trapped in hyrax dung. The results therefore add information for the interpretation of local vegetation shifts on land during the interval between 50 ka and 21 ka in Namibia.

Rapid spread of diseases in Caribbean coral reefs

The variety and frequency of diseased coral reef organisms has increased across the Caribbean during the last 10 years. Black band, white band, white pox, and white plague diseases have become more widespread. Yellow band disease now affects a major portion of Montastrea annularis across the Caribbean. Mortality of Yellow band disease-affected tissues was observed to increase in the southern Caribbean during early 1997 , with affected tissue turning white and dying. During the past two years a major fraction of encristing red calcareous Porolithon algae died across the Caribbean. This disease, also found in the Indian Ocean, lacks the orange band characteristic of Pacific coralline lethal orange disease. A millimeter thick white circular rim is seen between live tissue and dead skeleton. Numerous other emerging diseases have attacked many other organisms in this period, including gorgonians, sponges, and echinoderms. Many of those now known have not yet been described. Generally, most diseases affect one or few species (except white plague and black band diseases); and their spatial and temporal distributions appear unrelated to bleaching, pollution (except black band disease), sedimentation, or grazing. This paper brings together observations made separately by many researchers over a large area and long period; in order to evaluate the geographic and historical distributions of each disease: Photographic images are included which show diagnostic field criteria for recognizing each disease.

کانه زایی مس- نقره سولفید توده ای آتشفشان زاد نوع بشی در توالی آتشفشانی- رسوبی کرتاسه پسین: مثال موردی کانسار گرماب پایین، جنوب شرق شاهرود

کانسار مس- نقره گرماب پایین در توالی آتشفشانی- رسوبی کرتاسه پسین زیر پهنه سبزوار واقع ‌شده است. کانه زایی به شکل هندسی چینه‌سان و چینه‌کران در افق چینه‌ای خاص به همراه نهشته‌های برون‌دمی رخ‌داده است. سنگ میزبان کانه زایی را سنگ‌های آتشفشانی آندزیتی- داسیتی و آذرآواری‌های وابسته تشکیل می‌دهند. کانه زایی از کمرپایین به سمت کمربالا در چهار رخساره رگه- رگه‌چه ای، توده‌ای- نیمه توده‌ای، لایه‌ای و رسوبات برون‌دمی رخ‌داده است. کانی‌شناسی ماده معدنی شامل کانی‌های اولیه نظیر پیریت، مگنتیت و کالکوپیریت و کانی‌های ثانویه نظیر مس طبیعی، مالاکیت، کوپریت، کولیت و اکسیدهای آهن- منگنز است. دگرسانی سنگ دیواره، به‌طور عمده از نوع کلریتی و به مقدار کمتر شامل سیلیسی، آرژیلیتی و زئولیتی است. حداکثر عیار طلا و نقره در کانسار به ترتیب 1 و 19 گرم در تن است. به نظر می‌رسد که بروز فعالیت آتشفشانی زیردریایی در یک حوضه پشت‌کمانی در کرتاسه پسین، به تشکیل این کانسار سولفید توده‌ای نوع بشی منجر شده است.

A pilot trophic model for Golfo Dulce, a fjord-like tropical embayment, Costa Rica

Golfo Dulce is a deep tropical estuary whose ecosystem dynamics are poorly understood. In order to evaluate biomass and energy now distributions, productivity potential. and to obtain guidelines for conservation management, a steady - state model of 20 compartments (excluding detritus) was constructed using the: ECOPATH II software. Total system biomass (10.4 t/km2) and total energy throughput (sum of all flows, T = 1405 t/km2/year) of Golfo Dulce are small compared to other modeled coastal ecosystems. The mayor pan of the energy throughput is achieved from primarily pelagic trophic levels I to II (52%) plus 11 to III (41 %). The pelagic fish biomass consumed with in the system by top predators (about 1133t) exceeds twice The demersal fish biomass consumed (5021). Artesanal fishery primarily operates on the top trophic levels of the benthic domain and has a very low gross efficiency (catch/ primary production = 0.06%). A nearly balanced production/repiration ratio (P/R = 1.09) and a high mean tranfer efficiency (15%) suggest that the system is near maturity. Contradictory seem the low Ascendency (A= 32.2%) and high development Capacity (OC = 61.8%) values indicative of a relatively undeveloped system of little internal stability. This contradiction might be explained through the fact that much of the detrital matter produced within the euphotic zone is sedimented away and does not - like in other coastal systems - reenter the food web. Thus, whereas the pelagial represents a tightly coupled rather mature (sub) system, the Golfo Dulce as a whole lacks this degree of maturity due to a very inefficient benthic pelagic coupling, which results from its fjord-like topography. The model reveals that Golfo Dulce acts differently from most tropical coastal ecosystems: it is dominated by biomass and energy flow within the pelagic domain and ruther resembles an open ocean system than an estuarine one. Due to its low benthic biomass and low overall productivity, there seems to be no potential for further development of the demersal/semi-demersal fishery inside the gulf. An increase of the pelagic fishing pressure would seriously threaten the populations of resident predators such as dolphins, sharks and large bird species. which have considerable conservation and ecotourism values. Future ecosystem research in Golfo Dulce should focus on the pelagic part of the gulf (microbial loop, plankton, and nekton), on the small benthos. as well as on transfer processes within the pelagic: domain, between the pelagial and the brnthos, and at the river/gulf and gulf/ocean interfaces.

FTIR Analysis of a Light-driven Inward Proton-pumping Rhodopsin at 77 K.

Parvularcula oceani xenorhodopsin (PoXeR) is a light-driven inward proton pump that was discovered from deep ocean marine bacteria. PoXeR is categorized into the same family of Anabaena sensory rhodopsin (ASR) that functions as a photochromic sensor. In this study, we applied light-induced difference Fourier-transform infrared (FTIR) spectroscopy to PoXeR at 77 K, and the obtained spectra were compared with those of ASR. The structure and structural changes in the primary processes of PoXeR are common to all microbial rhodopsins. The red-shifted K formation (PoXeRK ) was accompanied by retinal photoisomerization from the all-trans to 13-cis form resulting in a distorted structure of the retinal. The observed hydrogen out-of-plane (HOOP) vibrations were sensitive to H/D exchange, indicating that the chromophore distortion by retinal isomerization is located near the Schiff base region in PoXeR. The hydrogen-bonding strength of the protonated Schiff base is similar between PoXeR and ASR, whose acceptor is presumably a water molecule. Unlike ASR, however, PoXeR contains strongly hydrogen-bonded water (O-D stretch at 2277 cm-1 in D2 O), which is also the case for outward proton pumps. The detailed structure, structural changes upon retinal photoisomerization, as well as functional correlation in PoXeR are discussed based on the present FTIR study.

Finding the Pearls in an Ocean of Data

Finding the Pearls in an Ocean of Data

PERMIAN AND TRIASSIC OF THE RUSHAN-PSHART ZONE (PAMIR)

Three isolated tectonic blocks Rushan, Pshart and Dunkeldyk have conventionally been grouped into the Rushan-Pshart zone. Because of stratigraphic and structural differences, they should be considered separately. The present paper mostly deals with the Pshart block, which is subdivided into East and West Pshart. This kind of subdivision may also be applied to the Dunkeldyk block. A summary of the characteristics of Upper Paleozoic and Mesozoic volcano-sedimentary successions confirms previous hypotheses, which suggest that these sequences have formed under crustal extension, accompanied by basaltic volcanism. These earlier models, however, postulated the existence of a vast oceanic area separating the East Pshart from SE Pamir during Late Permian, Triassic, and Jurassic. This ocean closed during the Early Cretaceous. The interpretation preferred in this paper suggests a narrow sea-way, which closed before the Cretaceous.

Linking optical and molecular signatures of dissolved organic matter in the Mediterranean Sea

Dissolved organic matter (DOM) plays a key role in global biogeochemical cycles and experiences changes in molecular composition as it undergoes processing. In the semi-closed basins of the oligotrophic Mediterranean Sea, these gradual molecular modifications can be observed in close proximity. In order to extend the spatial resolution of information on DOM molecular composition available from ultrahigh resolution mass spectrometry in this area, we relate this data to optical (fluorescence and absorption spectroscopy) measurements. Covariance between molecular formulae signal intensities and carbon-specific fluorescence intensities was examined by means of Spearman’s rank correlations. Fifty two per cent of the assigned molecular formulae were associated with at least one optical parameter, accounting for 70% of the total mass spectrum signal intensity. Furthermore, we obtained significant multiple linear regressions between optical and intensity-weighted molecular indices. The resulting regression equations were used to estimate molecular parameters such as the double bond equivalent, degradation state and occurrence of unsaturated aliphatic compounds from optical measurements. The statistical linkages between DOM molecular and optical properties illustrate that the simple, rapid and cost-efficient optical spectroscopic measurements provide valuable proxy information on the molecular composition of open ocean marine DOM.

Climatic Characteristics of Binary Tropical Cyclones in the Northwest Pacific Ocean

Climatic Characteristics of Binary Tropical Cyclones in the Northwest Pacific Ocean