Oceanography

Background and Objective: Cleanroom is a tightly enclosed environment where airborne particles are under control and is a necessary environment in pharmaceutical industries to produce quality products. Hence, we sought to assess and simulate particle dispersion and track particles in a cleanroom by computational fluid dynamics (CFD) method in a pharmaceutical industry. Materials and Methods: This experimental study was conducted in 2015 in a pharmaceutical industry. We evaluated particle concentration and number in the cleanroom according to ISO 14644 -3 standard. In addition, air flow pattern and particle dispersion in the cleanroom with cleanliness class of C was simulated based on CFD. The results showed that the path of particle movement and distribution and dispersion of particles in the cleanroom are completely dependent on flow shape and the pattern of air flow in the cleanroom. Furthermore, the simulation results showed that wall return had efficiency of higher than 70% for particle sizes of 0.5 and 5 microns. Equipment and tools existing in the cleanroom affect the air flow pattern, and in turn, particle removal efficiency. Moreover, particle dispersion simulation in the cleanroom illustrated that air flow pattern exerts the highest impact on particle removal in cleanrooms.

As the UK's National marine data centre, a key responsibility of the British Oceanographic Data Centre (BODC) is to provide data management support for the scientific activities of complex multidisciplinary long term research programmes. Since the initial cruise in 1995, the NERC funded Atlantic Meridional Transect (AMT) project has undertaken 18 north-south transects of the Atlantic Ocean. As the project has evolved there has been a steady growth in the number of participants, the data volume, complexity and the demand for data. BODC became involved in AMT in 2002 at the beginning of phase II of this programme and since then has provided continuous support to both the AMT and wider scientific community through rescue, quality control, processing and access to the data. The data management comprises a team of specialist data managers using a sophisticated infrastructure of software and hardware to manage, integrate and serve the physical, biological and chemical data. Here, we discuss the approach adopted, techniques applied and some guiding principles for management of large multi-disciplinary programmes.

The present investigation reviews published data on the feeding rates and prey selection of Oithona similis females, Calanus finmarchicus nauplii and females in the Irminger Sea in April/May and July/August 2002. Our aim was to examine how the feeding rates and prey selection of these three copepod stages respond to concomitant changes in microplankton community composition and prey abundance. Copepods typically ingested prey overall according to its ambient concentration although significant species and stage-specific differences in prey-type ingestion and selection were apparent. Despite being of comparable weight, the ingestion rates of C. finmarchicus nauplii were always higher than those of the O. similis females. Moreover, C. finmarchicus nauplii and O. similis females fed preferentially on diatoms and ciliates respectively, whereas adult female C. finmarchicus showed limited prey selectivity. Copepod grazing impact on total and on ciliates/ dinoflagellates standing stock was ,0.5 and ,2%, respectively. We attribute this result to a combination of low grazing rates, low copepod abundance and low microplankton biomass, all of which are indicative of the non-bloom conditions under which these experiments were conducted. The differences in copepod feeding rates and prey selection we report reflect species and stagespecific eco-physiological adaptations, which may act as important driving forces for marine ecosystem structuring and functioning.

The boreal copepod Calanus finmarchicus sequesters substantial amounts of carbon (C) in the deep layers of the North Atlantic Ocean through their contribution to the “lipid pump.” This pump is driven by these zooplankton descending from the surface layers to spend prolonged periods at depth during which time they metabolise substantial lipid reserves and a fraction suffer mortality. C. finmarchicus is principally a boreal species but is expatriated by currents flowing northwards into Arctic regions such as the Fram Strait, where it is now able to complete its life cycle. We considered how this expansion to its distributional range adds to the estimated magnitude of the lipid pump. Field sampling in the Fram Strait found C. finmarchicus abundance to be spatially variable with high values, equivalent to those reported for core distributional areas further south, found mainly in the eastern region. Lipid reserve levels were sufficient for many individuals to survive the overwintering p...

Warming, loss of sea icea and changes in ocean currents in the Arctic has led to biochemical changes in pelagic systems that propagate into, and disrupt the Arctic food web. The responses of plankton to environmental variability is critical in understanding how climate change may shape the structure of pelagic ecosystems in the Arctic. To further this understanding, we used a partial canonical correspondence analysis on remotely sensed and modelled hydroclimate together with plankton abundance data from the Continuous Plankton Recorder Survey from the Barents Sea in the European Arcticone of the fastest warming regions globally -to assess the spatial and interannual variability of plankton community assemblages. The hydroclimate explained ~50 % of interannual variability in species assemblage of plankton communities. Calanus spp. copepod abundances were particularly sensitive to changes in the hydroclimate, which were strongly associated with the mixed layer depth and nutrient concentrations. In warmer years, where SST exceeded those predicted under various future climate scenarios, we saw evidence of thermal stratification of the water column that supported populations of appendicularians, and the potentially toxin-producing diatom Pseudo-nitzschia. Spatial variability of the assemblage was strongly associated SST and salinity gradients that reflect different water masses. Such changes to plankton assemblages in response to hydroclimatic variability are likely to impact trophic interactions with associated organisms, many with ecological and economic significance in Barents Sea food webs.

A late Quaternary, current-lain sediment drift deposit over 30 m in thickness has been discovered on the continental shelf of East Antarctica in an 850 m deep glacial trough off George Vth Land. Radiocarbon dating indicates that a period of rapid deposition on the drift (averaging 290 cm/kyr) occurred in the mid-Holocene, between about 3000 and 5000 yr before present (yr bp). Slower deposition rates of around 10 cm/kyr, during the past 0±3000 yr and from 5000 to about 13000 yr bp, coincides with the deposition of bioturbated, ice-rafted debris (IRD) rich, sandy mud under an energetic bottom current regime. In contrast, the mid-Holocene (3000±5000 yr bp) sediments are ®ne-grained, laminated to cross-laminated with minimal IRD content, and are contemporaneous with a period of warmer marine conditions with less sea ice production. This pattern suggests that bottom currents were weaker than present day in the mid-Holocene, and that the rate of dense bottom water production was reduced at that time. This scenario is consistent with the hypothesis of non-steady state rates of Antarctic bottom water production through the Holocene as recently proposed by Broecker and his colleagues.

The Kara Sea receives ~ 1/3 of total freshwater discharge to the Arctic Ocean, mainly from the large Ob and Yenisei rivers. The Ob-Yenisei plume covers wide area in the central part of the Kara Sea during ice-free season (June-October) and accumulates ~ 1000 km 3 of freshwater volume. In late autumn, the Kara Sea becomes covered by ice, which hinders in situ measurements at this area. As a result, the fate of the Ob-Yenisei plume below sea ice during winter and spring remains unclear. In this study, we report multiple in situ measurements performed in the Kara Sea shortly before and during ice-covered season. We demonstrate that late autumn convection in the plume shortly before ice formation significantly reduces friction between the plume and the subjacent sea. The subsequent formation of solid sea ice coverage isolates the plume from wind forcing. These two factors precondition the Ob-Yenisei plume to form an intense buoyancy-driven coastal current below sea ice. As a result, the plume advects eastward to the Laptev Sea through the Vilkitsky Strait during several months in November-February. Eventually, by late winter this huge freshwater volume disappears from the Kara Sea and contributes to freshwater content of the Laptev Sea. The obtained result improves our understanding of freshwater balance of the Kara and Laptev seas, as well as provides an important insight into the large-scale freshwater transport in the Eurasian Arctic, which remain largely unknown during ice-covered season. River runoff to the Arctic Ocean (4200 km 3 y -1 ) accounts to 11% of total freshwater discharge to the World Ocean, which provides anomalously large freshwater input per unit area (0.28 m y -1 ) compared to the other oceans (0.08-0.18 m y -1 ) 1-3 . Spreading and transformation of freshwater runoff governs many physical (stratification, vertical mixing, ocean heat flux), chemical (nutrient cycle, acidification), and biological (primary production, food webs) processes in the Arctic Ocean 4-6 . In particular, it maintains salinity-driven density stratification and affects sea ice formation, which is of key importance for the Earth's albedo and global climate . The surface circulation in the deep Arctic is dominated by the anticyclonic Beaufort Gyre in the Canadian Basin and the Transpolar Drift, which flows from the northern parts of the East-Siberian and Laptev seas towards the Fram Strait 10 (Fig. ). The surface circulation at the wide Eurasian shelf is determined by spreading of large river plumes, which have significantly different dynamics, as compared to ambient saline sea . Large density gradient at the vertical plume-sea interface reduces vertical momentum transport between buoyant plumes and subjacent seawater 13 . As a result, plume dynamics are governed by wind forcing, buoyancy gradients and Coriolis force, while experiencing low influence of ambient sea circulation . The Ob-Yenisei plume (with area up to 250,000 km 2 ) located in the Kara Sea and the Lena plume (with area up to 500,000 km 2 ) located in the Laptev and East-Siberian seas are the largest plumes in the Arctic Ocean and among the largest in the World Ocean (Fig. ). These two plumes cover the majority of the Eurasian Arctic shelf during ice-free season in summer and autumn and determine local circulation, which was thoroughly

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

The most extensive and severe bleaching of coral ever recorded occurred in 1997 and 1998 as a result of anomalously high sea-surface temperatures. In the Ryukyu Islands, extensive bleaching occurred from late July to early October in 1998. A time-series transect study on a reef flat revealed the different responses of coral populations among species to this event. Coral cover was monitored just before, during, and 6 times after the bleaching occurred, along 5 fixed transects, 710 to 800 m long, across the reef flat of Shiraho Reef, Ishigaki Island, in the Ryukyu Islands of Japan. The dominant corals were Heliopora coerulea, massive Porites, and branching Porites, Montipora, Acropora, and Pavona (these latter 4 genera could not always be distinguished to species level, and are thus grouped by genus and ecoform). H. coerulea was the least susceptible to bleaching and maintained almost constant coverage before and after the bleaching. Massive Porites were susceptible to bleaching, but regained their algae after the bleaching and sustained their coverage. On the other hand, the branching Porites, Montipora, and Acropora were susceptible to bleaching and mortality was high. Coverage by branching Montipora was initially reduced by 66%, but by 2 yr after the bleaching it had recovered to pre-bleaching coverage. However, only large patches of more than 70 m along a transect, with coverage of 10 to 40%, recovered. Small patches of less than 30 m along a transect, with coverage of less than 10%, died and did not recover. The response of corals to bleaching differs according to the strategy the coral uses against bleaching; moderately frequent and severe bleaching might permit the coexistence of both types of corals on the same reef flat, as in the case of Shiraho Reef.

Carbon sequestrated in marine ecosystems has been termed “blue carbon”, and seagrass meadows are one of the most dominant blue carbon stocks. Globally, one of the major distribution sites of seagrass meadows is coral reef flat. Recent studies have revealed that the amount of sedimentary organic matter in tropical and subtropical coasts is comparable to that in temperate coasts. However, these estimations are based on a few data and have wide range. Since quantifying organic carbon in the carbonate sediment is technically difficult and costly, easier methods for estimating the amount of organic carbon in seagrass meadows are strongly needed to assess the global blue carbon stocks for mitigation of global warming. Seagrass biomass is suggested to have responsible for the variability of seagrass carbon sink capacity, but the models have not been presented yet. To identify the relationship between seagrass biomass and blue carbon stocks, we developed a new box corer which can facilitate...

The coral reef ecosystems at Palau Island have attracted growing attention recently. However, there are still many uncertainties about the coral reef ecosystems there because the characteristics of nutrient dynamics and primary production are expected to be largely different between shallow fringing coral reefs distributed in the Southern Japan and barrier reefs with deeper lagoon at Palau Island. Especially, how physical parameters such as light intensity, current velocity and wave strength, which vary depending on the water depth, control the primary production and material transport in the lagoon area is not yet well known. In this study, we investigated nitrogen cycles in the lagoon system combining the observations and several process studies: 1) distribution of nutrients and dissolved organic nitrogen in the water column, 2) depth-dependent characteristics of the surface sediment such as particle size, organic matter contents and nutrient profiles in the porewater, 3) flux of ...

The Indian Ocean Dipole (IOD), which governs climate variability not only over the Indian Ocean but also globally, produces precipitation anomalies in the East African short rain period from October to November. These precipitation anomalies were recorded in annual bands from a coral core obtained in the Malindi Marine Park, Kenya. A signature of the IOD in precipitation was detected in the coral core by luminescence intensity under UV light and by oxygen isotope values dated to January, a few months after the short rain period. Anomalies of the oxygen isotope values correlated well with high and low precipitation, which were related to positive and negative IOD indices, respectively. This study suggests that the coral annual band record is effective for reconstructing IOD events and should be able to reconstruct the IOD record prior to instrumental observations.

We measured the air-water CO 2 flux in four coastal regions (two coral reefs, one estuary, and one coastal brackish lake) using a chamber method, which has the highest spatial resolution of the methods available for measuring coastal air-water gas flux. Some of the measurements were considerably higher than expected from reported wind-dependent relationships. The average k 600 values for Shiraho Reef, Fukido Reef, Fukido River, and Lake Nakaumi were 1.5 ± 0.6, 3.2 ± 0.3, 0.69 ± 0.26, and 2.2 ± 0.9 (mean ± S.D.) times larger than the wind-dependent relationships. Results were compared with current-dependent relationships and vertical turbulence intensity (VTI). VTI is an index of water-surface stirring and is calculated from near-surface vertical velocity. Although some measurements from the reefs and river closely matched those expected from wind-dependent relationships, others were considerably higher. All data were correlated with VTI and were qualitatively explained by bottom macro-roughness enhancement. In Lake Nakaumi, results tended to differ from the wind-dependent relationships, and the difference between the measured and expected gas-transfer velocity was correlated with biological DO changes and/or the intensity of density stratification. We found these factors to have important effects on coastal gas flux. In addition, the chamber method was an effective tool for evaluating coastal gas flux.

Marine debris is rapidly gaining worldwide recognition as a major anthropogenic threat to global ocean ecosystems and produces a wide range of negative environmental, economic, safety, health and cultural impacts (UNEP, 2009). East Asia is the region with the fastest growing waste production in the world. Indonesia is in second position after China which produces the most waste in the world . The Beach Hygiene Index is a scaled index in a "Clean Coast" program launched by the Israeli ministry in an effort to solve the problem of littering on Israel's beaches. This index can be used as an indicator of pollution in a marine tourism area. The purpose of this study was to identify types of marine debris in the coastal waters of Karang Ria Tuminting and determine the value of the Clean Coast Index as an indicator of pollution. The collected data was then processed and statistically analyzed using Excel, Orange and SPSS software. Sampling was done by adapting the Shoreline Survey Methodology. approximately 1 month and made 2 direct observations, the plastic and rubber waste categories were found as the most common categories with the first observation being 73.4% and the second observation being 10.1%. The activities of the surrounding community are the main factors causing the abundance of marine debris around the coastal areas. The index value obtained is 39.5 with a total of 395 waste in various categories as stated by NOAA (2016).

Coastal lagoons are considered among the marine habitats with the highest biological productivity, and support a great variety of human activities and pressures that make them especially vulnerable to trophic imbalances. While dystrophic crises are common in many lagoons, others like the Mar Menor show homeostatic mechanisms, high resilience, and clear waters. This paper analyses the water column descriptors dynamic during the last 22 years in this coastal lagoon, in the context of a eutrophication process produced by an increase in nutrient inputs, mainly derived from agriculture. Despite water column nitrate concentration increased by one order of magnitude, the lagoon maintained homeostatic regulation for two decades, keeping the water transparency and relatively low levels of nutrients and chlorophyll a (Prebreak phase), followed by a sudden change of state in 2016 with an abrupt increase in average nutrients and chlorophyll a concentration and loss of water transparency (Break phase), and a relatively rapid recovery after the reduction of nutrient discharges (Recovery phase). The activation of the regulation mechanisms seems to manifest through an ammonium production in the water column, as a consequence of the activity in the trophic web. The low correlation between chlorophyll a and nutrients concentration, mainly at small spatio-temporal scales, is in disagreement with eutrophication traditional models, and suggests a rapid response of primary producers to nutrient inputs and a zooplankton control in the short-term, which in turn is controlled by the rest of the trophic web components. Homeostatic properties that in the Mar Menor lagoon have provided resistance to eutrophication are based on several mechanisms: channeling its production toward the benthic system (maintaining high biomasses of primary producers, filter feeders, and detritivores), a top-down control of the pelagic trophic web exerted by ichthyoplankton and jellyfish, and exporting surplus production outside

During the research programme conducted on the OVPuerto Deseadoin the summers of 2011 and 2013, 36 stations were sampled using a demersal net at depths between 53–590 m in the Antarctic Peninsula and South Shetland Islands. A total 3378 fish specimens belonging to 36 species were recorded. Notothenidae was the best-represented family in species number, withLepidonotothen nudifrons,L. larseniandTrematomus scottibeing the most numerous species. Of the fish assemblages, 20% of the species were considered as dominant, 10% as common, 13% as occasional and 57% as rare. Six groups (and two sub-groups) were obtained by the ordination diagram based on geographical location: group 1=Gerlache Strait, group 2=Deception Islands, group 3=Biscoe Island, group 4=between Elephant and King George islands, group 5=northern Antarctic Peninsula, and group 6=South Shetland Islands, with sub-groups 6a shallower South Shetland Islands and 6b deeper South Shetland Islands. Sampling depth and water temperatu...

The comprehensive utilization of floating breakwaters, specially acting as a supporting structure for offshore marine renewable energy explorations, has received more and more attention recently. Based on linear waterwave theory, the hydrodynamic performance of a T-shaped floating breakwater is semi-analytically investigated through the matched eigenfunction expansion method (MEEM). Auxiliary functions, to speed up the convergence and improve the accuracy in the numerical computations, are introduced to represent the singular behavior of fluid field near the lower salient corners of the structure. The effects of the height and installation position of the vertical screen on the reflection and transmission coefficients, dynamic response and wave forces are examined. It is found that the presence of the screen shifts the resonance frequency of RAO for both surge and pitch modes to the low-frequency area, while has no effect on heave mode. The identical added masses, damping and transmission coefficients can be obtained in the cases where the screen holds the same distance away from the longitudinal central axis of the upper box-type structure. Moreover, a relatively small pitch response can be achieved in a wide wave-frequency range, when the breakwater is Γ-shaped.

An analytical theory is developed to study the effects of a coaxial tube-sector-shaped supporting structure on the conversion efficiency of a suspended, circular OWC converter. An eigen-function expansion method is employed in a cylindrical coordinate system to study wave interaction with an OWC converter in finite depth of water. Effects of the supporting structure, OWC dimensions, wave direction on energy conversion efficiency, and optimization of power-takeoff devices are discussed. Our results show that the coaxial tubesector-shaped support with an opening in the range of π/ 2-5 π/ 4 can significantly increase the conversion efficiency and widen the frequency range over which the conversion efficiency is high.

The paper presents long-term dynamic of the Anapa bay-bar submerge slope. The Anapa bay-bar submerge slope contains five morphological elements -Solenoe Lake, Bugazskaya bay-bar, Blagoveshchensky butte, Vityazevskaya bay-bar, section from Vityazevo to Anapa. The erosion-accumulation sites change from year to year. In general, from 2012 to 2018 the amount of sediments on the Anapa bay-bar submerge slope decreased by 1.89 million m 3 . On the sites Solenoe lake and Blagoveshchensky butte from 2012 to 2018 accumulation are 0.20 and 0.14 million m 3 , respectively. On the sites Bugazskaya and Vityazevskaya bay-bars from 2012 to 2018 erosion are 0.52 and 0.64 million m 3 , respectively. On the section from Vityazevo to Anapa from 2013 to 2018 erosion is 1.08 million m 3 . The greatest changes in the underwater relief occur in a 600-meter coastal area to a depth of 6-7 m. The underwater bars are formed and moved just in this area.

Pulau Gili Ketapang merupakan salah satu Pulau di Kabupaten Probolinggo yang menjadi salah satu tempat budidaya perikanan di daerah Kabupaten Probolinggo. Penelitian bertujuan untuk menganalisis atau mengevaluasi kesesuaian penempatan Keramba Jaring Apung di Pulau Gili Ketapang menggunakan parameter Hidro-Oseanografi. Metode pengambilan sampel pada penelitian ini menggunakan metode purposive sampling, pada bulan desember 2022. Setelah mendapatkan data primer dandata sekunder kemudian dilakukan proses overlay untuk mengetahui kesesuaian lahan untuk Keramba Jaring Apung. Sedangkan metode yang digunakan untuk analisis hasil penelitian menggunakan metode scoring. Tipe pasang surut dipulau Gili Ketapang campuran harian ganda, nilai kecepatan arus paling besar 0,3-0,4 m/s pada musim peralihan 2,Gelombang tertinggi pada musim barat dengan ketinggian 0,3-0,4 m. Hasil dari penelitian Keramba Jaring Apung yang berada dibagian tenggara Pulau Gili Ketapang dapat dikategorikan sangat sesuai untuk budidaya ikan kerapu, dan untuk Keramba Jaring Apung yang berada dibagian barat daya Pulau Gili Ketapang dikategorikan sesuai untuk dijadikan budidaya ikan kerapu.

Understanding of the spatial distribution of fish habitats is crucial in order to achieve optimum fishing and to increase efficiency of marine resource management. In this study, seasonal potential suitability habitat model for Rastrelliger kanagurta off the east coast of Peninsular Malaysia was derived using maximum entropy (MaxEnt) by utilizing fishing locations and environmental parameters from remotely sensed sea surface temperature (SST) and chl-a concentration (chl-a) data. The influence of environmental parameters on the formation of the potential fishing zones was also determined. The results showed that all the seasonal models performed significantly better than random with AUC > 0.80, which indicated that the constructed models were applicable with 'good' to 'excellent' predictive accuracy. The model also showed that chl-a influenced R. kanagurta's potential fishing ground during northeast and intermediate monsoon of October. Meanwhile, SST contributed more in defining the potential fishing grounds during southwest and intermediate monsoon period of April. The seasonal and spatial extents of potential fishing grounds were largely explained by chl-a (0.32-0.42

Three wells were studied, using apatite fission track dating, in the offshore of southern Alaska that make a crude transect southward from Lower Cook Inlet to the Kodiak Shelf and include the ARC0 Lower Cook Inlet COST #I well, the Chevron OCS-0248 # l A well (Shelikof Strait), and the Kodiak COST KSSD #I OCS 77-1 well (Stevenson Basin, Kodiak). The ages of partially-annealed samples from lower Cook Inlet well suggest that the region cooled either between -100-75 Ma or sometime after. Two permissable scenarios are presented to infer the post-Late Jurassic buriallthermal history of the LC1 well. One has maximum heating followed by cooling in Late Cretaceous times and the other has maximum heating followed by cooling during mid-Tertiary times. Although we are unable to prove which scenario is most valid on the basis of the thermal data from this well alone, mid-Tertiary or later uplift and cooling is preferred because data from the Shelikof well suggests that the mid-Cretaceous unconformity was a minor one relative the mid-Tertiary unconformity. Because of the estimated difference of -12°C between past and present temperatures deep in the well, the base of the well is only -500 m shallower now than during maximum burial (12"C124"C/km geothrmal gradient). Single-grain ages deep in the Shelikof well approach the age of the mid-Tertiary (Miocene) unconformity (-23 Ma) and, therefore, it is interpreted to be the major unconformity in the upper part of the Shelikof well section. The Late Cretaceous unconformity is considered to be minor in comparison. In this scenario the Shelikof well section was buried deepest, and was therefore hottest, until the onset of mid-Tertiary erosion. Approximately 665 m of late Tertiary and Quaternary strata have since been deposited in Shelikof Strait and has reburied the underlying section to within -536 m of its original maximum burial depth. The section has also been submerged beneath 166 m of water since then so the Shelikof well section has experienced a total of -1 km of submergence below sealevel since -25 Ma (832 m section+l66 m water = 998 m). It follows that the base of the well is only -290 m shallower now than it was during maximum burial. Single-grain ages deep in the Kodiak KSSDl well are as young as 20-25 Ma and approach the age of overlap of a mid-Miocene regional unconformity (<23 Ma). The deepest Eocene deposits sampled were exhumed to within 574 m of the Miocene unconformity surface and have since been reburied by -1.7 km of late Tertiary strata. The total section prior to exhumation is interpreted to be -5 km; this suggests that Oligocene-age deposits may once have existed in the Stevenson Basin. Together with the known Eocene sections such deposits were exhumed during -4.4 km of uplift and erosion during a short interval in early-to middle Miocene times (>25-23 Ma). Unique and anomalous apatite compositions (high F-, low C1-, moderate OH-) from the Eocene section could provide a chemical tracer for determining the sediment source along the northeast Pacific rim.

The distribution and variability of picoplankton and nanoplankton in Admiralty Bay (King George Island, South Shetland Islands, Antarctica) were studied by investigation of five sampling sites during the austral summer of 2010/2011. After a relatively warm winter, the water temperature in the early summer ([0.02 °C) was higher than is normal in December. The spatial-temporal variability of salinity was low, whereas water temperature and chlorophyll a increased significantly (p \ 0.05) toward late summer. Nitrite and phosphate concentrations increased whereas nitrate and silicate decreased during the summer. Picoplankton increased by late summer and was dominated by heterotrophs ([96 %), with abundance and biomass tenfold (*10 9 cells L -1 ) and twofold (*60 lg C L -1 ) higher, respectively, than were observed in previous studies. In contrast, nanoplankton was dominated by photoautotrophs ([60 %), and values were highest in the early summer, with cell numbers (*10 6 cells L -1 ) and biomass (*90 lg C L -1 ) a factor of two lower than those found in a previous study. Temperature changes, inputs from ice melting, and grazing relationships between planktonic components seemed to have crucially important effects on the distribution patterns of these pico and nanoplankton communities. We suggest that additional study must be performed to develop a better understanding of abiotic and biotic factors that affect the abundance, biomass, and production of plankton smaller than 20 lm, their place in the microbial food web and the possible consequences of environmental changes on higher trophic levels in such Antarctic coastal environments as Admiralty Bay ASMA.

Contributions of filamentous and picoplanktonic cyanobacteria to the phytoplankton community structure were examined in New Caledonian waters during the 2001-2003 El Niño period at three stations. Morphometric characteristics of diazotrophic filamentous cyanobacteria are given as well as the seasonal and inter-annual variations of their surface areas and integrated abundances. Trichodesmium tenue and T. thiebautii were the dominant species followed by T. erythraeum, altogether accounting for more than 51-80 % of the biomass of the free-living filamentous cyanobacteria. Katagnymene spp. accounted for a smaller percentage (<13.8 % at ocean stations, <3.6 % in the lagoon). R. intracellularis biomass was relatively small (<1 % of total surface area and volume of Trichodesmium trichomes) with the highest ! concentration observed in summer (735 trichomes l -1 ). Colonies of unidentified cyanobacteria composed of spherical cells accounted on average for <1 % of the Trichodesmium biomass, with values exceeding 4000 cells l -1 . Abundance of filamentous cyanobacteria varied according to environmental factors, with summer 2001-2002 characterized by low filamentous diazotroph abundance and summer 2003, occurring at the peak of the 2001-2003 El Niño, particularly rich in filamentous cyanobacteria (with a maximum Trichodesmium spp abundance of 4500 trichomes l -1 in the Loyalty Channel). A similar variability pattern was observed for large diatoms and dinoflagellates, and for all picoeukaryotic populations. Different biomass estimators are provided as cell abundances, pigment concentrations including chlorophylls and phycoerythrin, and carbon content. The filamentous communities dominated in summer in oceanic waters while

The Middle Atlas, like all the structural domains of Morocco, is full of geosites of varying size and nature ranging from the microscopic scale to the scale of the outcrop. These rich geologic heritage offer high potential for scientific, pedagogical, and recreational, scenic, cultural, economic and geotouristic uses within the framework of sustainable development. This work has for objective to identify the conceptions of Moroccan students in the second year of secondary college and of futures teachers of Life and Earth Sciences (SVT) at the regional center for the trades of education and training (CRMEF -Meknes) about the presence of volcanoes in Morocco, Especially the volcanoes of the Middle Atlas which are articulated in the turns of the concept "geosite". The used methodology is based on a questionnaire addressed to the target population earth in Meknes and sale cities. The results of our study show that this heritage are not known to the interviewees. This article aims to : Highlight the volcanic chain of the Middle Atlas, Present the results of this study, and try to identify recommendations on the way forward as well as by education and sensibilization and other important means.

Coastal and estuarine zones are used by fish as nursery, spawning and feeding grounds. However, these essential habitats are characterized by the presence of both natural and anthropogenic stressors that may represent potential threats for the wellbeing of aquatic organisms, particularly fish. The main objective of this study was to evaluate and understand the effects of environmental stressors, both natural and anthropogenic, on coastal fish species using Ramnogaster arcuata as bioindicator. Fish were captured in two zones with different human activity levels: a highly impacted zone in Bahía Blanca Estuary (BBE) and a lightly impacted zone in the adjacent coastal zone (ACZ). Various indicators were used to determine fish responses to environmental stress. Main differences found between fishes from the two zones were in the condition index, trophic ecology (including feeding activity and diet composition) and liver metabolic biomarkers (ALT/AST enzymes, protein levels and lipid peroxidation). On the other hand, metal concentration levels analyzed in muscle did not show important differences between both environments. Physiological responses of R. arcuata from both zones were strongly correlated with natural stressors.

Intertidal sediments of the inner and middle zone from the Bahı ´a Blanca estuary were sampled for geochemical and environmental assessment of metals (Cd, Cu, Pb, Zn, Mn, Ni, Cr and Fe). Results indicate that both the organic matter content and the sediment grain size plays an important role in controlling the differential concentrations of the metals found in sediments from both zones. For most of the elements (except Mn), sediment metal concentrations were greater in the middle zone, although the concentrations did not exceed the maximums for quality of marine sediments. In this sense, anthropogenic impact (i.e., sewage drain) appears to be a key factor in the distribution of metals within the estuarine system. Comparing the levels obtained with quality levels (LEL and SEL), except Cu that showed levels slightly above the LEL, the rest of the concentrations of metals were lower to those levels. The low metal concentrations obtained within this highly impacted estuarine system suggest that the great volume of water that flooding the extensive flats in each tidal cycle has much importance. Although the potential risks of metals to the estuarine environment were low, taking into account the toxicity of some of these metals, continuity of monitoring is highly recommended.

a two-week International Marine Bivalve Workshop (IMBW) on marine molluscs, with an emphasis on systematics, anatomy, and natural history of bivalves, was held in Chantaburi, Thailand, to increase understanding of the poorly known molluscan fauna of Kungkrabaen Bay, Gulf of Thailand. The volume here introduced largely presents research initiated at this workshop, as a product of the seven scientist-student teams that worked together in the fi eld. Results of other projects by the participants have been added on general aspects of the regional molluscan faunas as well as on various species of gastropods.

Two different types of numerical ocean circulation models are used in a classical idealized problem, the thermally induced circulation in an ocean basin bounded by two meridians to the east and west and by the equator and a line of constant latitude. A simple scaling theory exists for predicting poleward heat transport and the strength of meridional overturning as a function of vertical diffusivity and other external factors. However, previous studies have indicated conflicting results, and other scaling laws have been proposed. Experiments with two widely used types of numerical models, one based on depth coordinates and the other based on isopycnal layers, provide insight into the discrepancies of previous studies. In the numerical experiments vertical diffusivity is varied over a range of 200. The source of the difficulty in previous studies is in part traced to applying a fixed restoring coefficient at the upper boundary and considering the buoyancy forcing at the surface fixed irrespective of vertical diffusivity . Globally or zonally averaged results show a robust agreement between the two models and support the simple scaling law in a flat-bottom basin and a bowl-shaped basin, as long as the meridional circulation is estimated along isopycnal surfaces and in situ rather than externally imposed restoring density differences are used to estimate the geostrophic-scale velocity. Over the thermocline the vertical mean of the zonally averaged zonal baroclinic pressure gradient has constant ratio to the vertical mean of the zonally averaged meridional baroclinic pressure gradient, consistent with the scaling assumptions for a diffusive thermocline.

The Yellow Sea (YS) environmental and ecological changes during the Holocene are driven by the interactions between the Yellow Sea Warm Current (YSWC), the East Asian Winter Monsoon (EAWM) and the Kuroshio Current (KC). We report marine biomarker records of brassicasterol, dinosterol and C 37 alkenones in core ZY1 and core ZY2 from the South Yellow Sea (SYS) to reconstruct the spatial/temporal variations and possible mechanisms of phytoplankton primary productivity and community structure changes during the Mid-late Holocene. The contents of the corresponding biomarkers in the two cores are similar, and they also reveal broadly similar temporal trends. From 6 kyr to 3 kyr, the biomarker contents in the two cores were relatively low with small oscillations, followed by a distinct increase at about 3 kyr indicating productivity increases caused by a stronger EAWM. The alkenone/brassicasterol ratio (A/B) is used as a community structure proxy, which also showed higher values in both cores since 3 kyr, indicating increased haptophyte contribution to total productivity. It is proposed that the YS community structure has been mainly influenced by the YSWC, with stronger YSWC influences causing an increase in haptophyte contribution since 3 kyr. Some differences of the biomarker records between ZY2 and ZY1 suggest spatial variations in response to YSWC and KC forcing. When the KC was intensified during the periods of 6 -4.2 kyr and 1.7 -0 kyr, the YSWC extended eastward, exerting more influence on core ZY1. On the other hand, when the KC weakened during 4.2 -1.7 kyr, the YSWC extended westward, exerting more influence on the ZY2.

The subaqueous delta of the Huanghe (Yellow River) has been StUdied using high-resolution acoustic systems. There are many subtle variations in sea floor morphology and sediment geometries; Smooth, featureless areas are rare, The main components of the SUbaqueous delta include broad, shallow channels; moderately disturbed areas with near-surface cut and fill structures; heavily disturbed areas with sea floor depressions, pits, and gullies; and a Smooth, gently sloping distal delta apron or "rise." These features are not directly related to sediment settling from dilute surface plumes but are due to gravity-driven hyperpycnal underflows, submarine mass movements, and silt flows.

The objectives of this research are to analyze characteristics of physical oceanography, such as : tides, waves, currents, and discharges at Muara Kali Porong. This research also discuss sediment flow patterns and morphology in around the Estuary of Porong River. Tidal data were used as correction to the depth. The calculation to determine the tidal current velocity and wind data along with current data are used for simulation model. Sedimentation process with a simulation of 15 days in the West Season occured in the Northeast of Lusi Island with sediment thickness ranged from 1.6 to 2.6 m.

The initiation of Northern Hemisphere glaciation in the subarctic North Pacific at ∼2.73 Ma was marked by an abrupt cessation of high opaline accumulation, considered to result from an increased stratification of the water column that should have led to higher utilization of nutrients in the surface ocean. We present a new stable Si isotope‐based record of Si utilization that is hard to reconcile with this model. A drop in 30Si/28Si by 0.4‰ at 2.73 Ma is coincident with an increase in bulk N isotope composition. The contrasting utilization records cannot have been both caused by a hydrographic change alone. Excluding a change in the Si:N export ratio, these results either imply a relative increase in silicic acid supplied to the surface waters or a change in its Si isotope composition. While it is impossible to distinguish between these two possibilities, both imply a regional or global change in the Si biogeochemical cycle, potentially caused by an enhanced storage of Si in the und...

The distribution of silicon in the North Pacific is controlled by the utilization of silicic acid by diatoms, a process that fractionates silicon (Si) isotopic compositions. Silicon isotope variations are presented for six water column profiles from the surface mixed layer down to the deep waters of the North Pacific Ocean. Although the observed Si isotopic variations display an apparently simple inverse relationship with dissolved nutrient concentrations, in fact they reflect mixing of surface waters undergoing active Si isotope fractionation and deep-waters with more uniform concentrations and isotope compositions. Samples from the surface of the subtropical gyre have the lowest dissolved Si concentrations and heaviest Si isotope compositions of marine waters measured thus far. Fractionation in the surface waters follows a typical Rayleigh-type distillation curve for a 'closed' surface water reservoir resulting from stratification of the surface layer in the subarctic region. In contrast, an 'open' system prevails within the subtropical gyre where there is significant recycling of silicic acid in the upper water column and lateral transport of silicon within surface currents. For deep waters, the Si isotope composition distinguishes between the northern North Pacific Deep Water (NPDW) and the southerly-derived bottom water. The relatively light Si isotope compositions measured from waters within the subarctic gyre provides evidence for isolation of the nutrient pool in the North Pacific.

The riverine flux of U that enters the deep oceans is not well constrained since the net losses during estuarine mixing are difficult to quantify. Riverine-dissolved U normally has a higher 234 U/ 238 U activity ratio ( 234 U/ 238 U ar ) than the uniform value that characterizes open ocean seawater and could be used as a tracer of riverine inputs if one could resolve subtle variations in seawater composition. Using new mass spectrometry techniques we achieve a long-term reproducibility ±0.3‰ on 234 U/ 238 U ar which permits the tracing of riverine U in seawater samples from the Arctica partially restricted basin that is ideal for such a study. We find that surface waters from the Arctic basins carry elevated 234 U/ 238 U ar when compared with deep ocean seawater. Samples from the Canada Basin have a significant freshwater component and provide evidence that the Mackenzie River loses ∼ 65% of its U in the Mackenzie shelf/estuary zone before entering the deeper basin. This is in contrast to samples from the Makarov Basin, which provide evidence that all of the freshwater input is derived from the major Yenisey River alone, despite the proximity of the Lena and Ob Rivers. The differing behaviour of U between the Mackenzie and Yenisey Rivers is most likely a consequence of the strong binding of U to dissolved organic matter (DOC) or secondary phases in these rivers. The Yenisey River appears to transport the majority of the DOC through the shelf and into the Makarov Basin. In contrast, the Mackenzie River appears to lose a significant amount of DOC (N 50%) in the estuary/shelf zone, which may lead to loss of associated U. These findings offer a more detailed picture of the fresh riverine water flow patterns in the Arctic Ocean when compared to other geochemical proxies. The non-conservative behaviour of U in the Mackenzie River through the shelf/estuaries has important implications for U input into oceans and the total marine budget.

This study investigated the relationship between variations in the size distribution and the specific surface area of SiO 2 nanoparticles and the in(stability) and rheology of their colloidal dispersions and their resulting silicapoly(acrylamide) hybrids. Thus, SiO 2 nanoparticles with size distribution in the range 40-173 nm, corresponding to 70-26 m 2 /g of specific surface area, were used in the studies. The results show a correlation between the average particle size distribution/the specific-surface area of silica nanoparticles with the in(stability) and the rheology of their dispersions, such that an increase in the particle size distribution from 40 to 173 nm corresponds to a decrease in dispersion instability index from 0.913 to 0.112. However, in the silica-poly(acrylamide) hybrids, a change in the particle size distribution from 40 to 173 nm corresponds to an increase in the nanofluid instability index from 0.1913 to 0.929. In the hybrid materials, interactions between polymer chains and nanoparticles lead to size-induced stability and rheological behaviour, such that the broadening of the FTIR peak around 1,000 cm -1 in the nanohybrids was related to an Si-O-H bending vibration that arose because of dominating hydrogen bonding arising from the interaction of the hydroxyl groups and the amide groups in the polymer. The rheological characteristics of the hybrid nanofluids show that the relative viscosity and shear sensitivity of the colloidal dispersions or their hybrids can be tailored by the average particle size distribution of the nanoparticles.

The intra-seasonal variability noticed in the thermohaline characteristics in the upper layers of the Arabian Sea during the summer monsoon season of 1973 is described with the aid of repeat transects made by USSR and Indian ships along some typical zonal and meridional sections covered during the pre and post onset regimes of Indo-Soviet Monsoon Experiment (ISMEX-73).  An attempt is made to compare this observed variability during the summer monsoon seasons of 1971, 1972 and 1973 with the limited available data sets. The observed short-term variability during the pre and post onset regimes at one station (60OE) on the equator and another station    (18O N, 67O E) in the northeastern Arabian Sea is described and discussed to highlight the uneven response of the Arabian s\Sea in its spatial domain to the variable seasonal monsoonal forcing.

The generation of high-resolution data is increasingly important in understanding the complexities of coastal ocean and developing sound management strategies, especially in view of the long-term impact of severe weather systems. The impact of severe weather systems, when integrated over time, can be significant when compared with tidal oscillations. This paper presents a study of water transport out of Vermilion Bay in response to a short, intense event associated with a passing atmospheric cold front, and reports the application of an Acoustic Doppler Current Profiler (ADCP) mounted on an Automated Surface Craft (ASC), known as the auto-boat or unmanned boat, developed in our lab at the Louisiana State University, to generate high resolution data accurately at a fraction of the cost of a manned boat. In our study, we used a manned boat and an unmanned boat, each for over 24 h to cover an entire diurnal tidal cycle, to measure flow velocity profiles to calculate the total transport. A stationary ADCP was deployed in the Southwest Pass of the Vermilion Bay from May 2009 to April 2012, providing data almost continuously (with only one major gap), with a 717-day record of water transport between the northern Gulf of Mexico and Vermilion Bay, and demonstrates the importance of the pass in water transport.

The climate of the early nineteenth century is likely to have been significantly cooler than that of today, as it was a period of low solar activity (the Dalton minimum) and followed a series of large volcanic eruptions. Proxy reconstructions of the temperature of the period do not agree well on the size of the temperature change, so other observational records from the period are particularly valuable. Weather observations have been extracted from the reports of the noted whaling captain William Scoresby Jr., and from the records of a series of Royal Navy expeditions to the Arctic, preserved in the UK National Archives. They demonstrate that marine climate in 1810-1825 was marked by consistently cold summers, with abundant sea-ice. But although the period was significantly colder than the modern average, there was considerable variability: in the Greenland Sea the summers following the Tambora eruption (1816 and 1817) were noticeably warmer, and had less sea-ice coverage, than the years immediately preceding them; and the sea-ice coverage in Lancaster Sound in 1819 and 1820 was low even by modern standards.

The Cliffs of Lumignano (Northern Italy) are a renowned climbing area, set on the steep walls of lower Oligocene limestones of the Castelgomberto formation which are made mainly of coral boundstone. Lumignano lies approximately on the south-eastern margin of a Cenozoic carbonate platform known as the Lessini Shelf, but the depositional environment of coral reefs is still debated, and it is unclear whether it was a Caribbean-type carbonate platform with a lagoon and steep slope, or a carbonate ramp with coral reefs on the mid ramp. We produced a geological map of the Lumignano area, in which five lithofacies are distinguished and mapped within the Castelgomberto formation. Their spatial distribution and main sedimentological characters outline that landward of coral reefs, a high-energy environment was present and was shallower than the reefs. Seaward of coral reefs, coralline algae and marlstones with bryozoans occur, while no evidence of a slope made of coral rubble was found. Hence, the detailed geological mapping and the documentation of the stratigraphic relationships between lithofacies provided a valuable contribution to the understanding of depositional environments of the lower Oligocene Lessini Shelf. This work also suggests elements for a better definition of the Castelgomberto formation, which could be split in members or lithofacies that can be mapped at a reasonably large scale (1:10000). The coralline algal lithofacies of the Castelgomberto formation is locally indistinguishable from the analogous facies of the underlying Priabona formation, but the boundary between these two units is always marked by an unconformity, which is easy to identify and may be used for the lithostratigraphic definition of the Castelgomberto formation.

This study was conducted in the sea system of Taranto (south Italy) to explore the consequences of the COVID-19 lockdown of all human activities on zooplankton abundance and composition. Copepoda were selected as the best indicators and four different dates were taken to represent the annual variability. The availability of samples from past collections (15 and 30 years ago) allowed comparison with previous situations. The Copepoda community in the most confined part of the system (stations MPI and MPII) was dominated by small-sized species and showed new arrivals, including Acartia tonsa, Centropages hamatus, and Pseudodiaptomus sp. The first inlet of Mar Piccolo (MPI) showed an unusually high number of species in the summer of 2020, just at the end of the lockdown period (March-May 2020). The evident growth of species richness at station MPI, and only during the summer of 2020, suggests a role of the lockdown period on the zooplankton composition. The high species richness in the post-lockdown period was probably the result of ceasing the disturbance caused by ship/boat traffic at the MPI site, which is heavily affected by daily human activities at sea.