Prediction of Changeable Eddy Structures around Luzon Strait Using an Artificial Neural Network Model

Mesoscale eddies occur frequently in the Luzon Strait and its adjacent area, and accurate prediction of eddy structure changes is of great significance. In recent years, artificial neural network (ANN) has been widely applied in the study of physical oceanography with the continuous accumulation of satellite remote sensing data. This study adopted an ANN approach to predict the evolution of eddies around the Luzon Strait, based on 25 years of sea level anomaly (SLA) data, 85% of which are used for training and the remaining 15% are reserved for testing. The original SLA data were firstly decomposed into spatial modes (EOFs) and time-dependent principal components (PCs) by the empirical orthogonal function (EOF) analysis. In order to calculate faster and save costs, only the first 35 PCs were selected as predictors, whereas their variance contribution rate reached 96%. The results of predicted reconstruction indicated that the neural network-based model can reliably predict eddy structure evaluations for about 15 days. Importantly, the position and variation of four typical eddy events were reconstructed, and included a cyclone eddy event, an eddy shedding event, an anticyclone eddy event, and an abnormal anticyclone eddy event.

Effects of In-Channel Structure on Chinook Salmon Spawning Habitat and Embryo Production

Adult salmonids are frequently observed building redds adjacent to in-channel structure, including boulders and large woody debris. These areas are thought to be preferentially selected for a variety of reasons, including energy and/or predation refugia for spawners, and increased hyporheic exchange for incubating embryos. This research sought to quantify in-channel structure effects on local hydraulics and hyporheic flow and provide a mechanistic link between these changes and the survival, development, and growth of Chinook salmon Oncorhynchus tshawytscha embryos. Data were collected in an eight-kilometer reach, on the regulated lower Mokelumne River, in the California Central Valley. Nine paired sites, consisting of an area containing in-channel structure paired with an adjacent area lacking in-channel structure, were evaluated. Results indicated that in-channel structure disrupts surface water velocity patterns, creating pressure differences that significantly increase vertical hydraulic gradients within the subsurface. Overall, in-channel structure did not significantly increase survival, development, and growth of Chinook salmon embryos. However, at several low gradient downstream sites containing in-channel structure, embryo survival, development, and growth were significantly higher relative to paired sites lacking such features. Preliminary data indicate that adding or maintaining in-channel structure, including woody material, in suboptimal spawning reaches improves the incubation environment for salmonid embryos in regulated reaches of a lowland stream. More research examining temporal variation and a full range of incubation depths is needed to further assess these findings.

Feeding habits of Paralabrax nebulifer (Serranidae) during reproductive and non-reproductive seasons in an adjacent area to Magdalena Bay, Baja California Sur, Mexico

The barred sand bass Paralabrax nebulifer is a commercially important fish off the west coast of Baja California Sur. To assess the diet of this species and variations as a function of sex and reproductive condition, 60 specimens were captured using traps during seven seasonal sampling trips from August 2016 to August 2018 in an adjacent area to Magdalena Bay, Baja California Sur, Mexico. The stomach contents of 50 specimens were obtained (23 males and 27 females). Sex was diagnosed by direct observation of the gonads. Based on the gonadosomatic index, hepatosomatic index, and histological analyses, the reproductive season of the barred sand bass was corroborated for August 2016, April, August, and September 2017, and August 2018, and the non-reproductive season was corroborated for November 2016 and March 2018. The Index of Relative Importance (IRI) was used to classify the main diet components, which comprised three fish species, seven crustacean species, and one mollusk species. According to the IRI, the South American pilchard Sardinops sagax and the red pelagic crab Pleuroncodes planipes were the prey that contributed the most (55%) to the barred sand bass diet. The ANOSIM showed that there were significant differences in the amount and type of prey consumed by sex; the SIMPER analysis revealed that the species contributing the most to differences between the sexes were S. sagax (16.58%), Euphylax dovii (15.95%), Stenocionops ovata (12%), and P. planipes (11.82%) for females. There were significant differences in the amount and type of prey consumed between types of reproductive season; the species contributing the most to differences between seasons were Anchoa spp. (27.76%), and P. planipes for non-reproductive season (22.67%), and S. sagax (11.08%) for reproductive season. The feeding strategy of the barred sand bass was that of a specialist carnivorous predator that fed mainly on the fish Sardinops sagax during the reproductive season, which supply the dietary nutritional requirements of the lipids HUFA (arachidonic acid, 20:4n-6; eicosapentaenoic acid, 20:5n-3; docosahexaenoic acid, 22:6n-3), nutrients required to achieve reproductive success.

Results of researches of some rare species of raptors in the Nechkinsky National Park, Russia

This report presents the selected results of rare birds of prey studies in the Nechkinsky National Park (Udmurt Republic, Russia) 20 years after the first studies undertaken here by I.V. Karyakin in 1991–1996. The main efforts were directed to the study of the White-Tailed Eagle (Haliaeetus albicilla). At the same time, the identification of other rare species was made. The studies were carried out during short visits to the territory in 2016, 2017, 2019 and 2021. In the national park (NP), within the previously known breeding areas, 3 new nests were identified. They were 0.9–1.6 km displaced from the locations of the old nests found 20 years ago. A new breeding territory was found in the adjacent area near the border of the NP. Despite the incomplete study of the area, it is assumed to be 8-9 breeding areas in the national park, and 2–3 areas directly along its borders. The number of breeding pairs of eagles in comparison with the first half of the 1990s, according to the author, remains stable, and population increase, as happened on the Lower Kama in Tatarstan, has not been observed here. Eagles nest on large, old-growth pines and larch trees, with a distance of 130–530 m deep into the forest from the outer edge. The distance to the Kama River is 0.68 km on average (0.13–1.3 km, n=4). The minimum distance between the nearest neighbors in the Kama valley, unregulated by the reservoir, is currently 3.6 km, the average (n=3) – 3.9 km. Eagles breed occasionally on and off. No reproduction was recorded for 2–3 years. The period of egg laying extends for a month from the beginning of March to the beginning of April. The death of young birds on 6-10 kV power lines was revealed, as a result, the owners were obliged to equip the power lines with bird protection devices. White-Tailed Eagle nestlings were ringed with colored rings. Two repeated observations were obtained from the lower reaches of Kama. The Greater Spotted Eagle (Aquila clanga) continues to inhabit the National Park, which is confirmed by the meetings of adult birds. There has been two-three times population of the Peregrine Falcon (Falco peregrinus) in comparison with the first half of the 1990s. Breeding of this falcon was found on 2 territories with a distance of 16.5 km between them.

Middle devonian-lower frasnian natural hydrocarbon reservoirs of the Pechora Sea shelf and Timan-Pechora oil and gas province adjacent area

The research is based on the three-layer natural hydrocarbon reservoirs theory, which allocates 3 layers in a natural reservoir – the genuine seal, the productive part and the intermediate layer situated between them - the false seal. The Middle Ordovician-Lower Frasnian terrigenous complex variable in thickness, composition and stratigraphic completeness sub-regional natural reservoir was identified in the northern part of the Timan-Pechora oil and gas province adjacent to the Pechora Sea. It includes several zonal and local natural reservoirs (Middle Ordovician-Lower Devonian, Middle Ordovician-Eiffelian, Zhivetian-Lower Frasnian and others). The distribution areas of these natural reservoirs were extrapolated to the Pechora Sea offshore. The areas with the highest prospects of oil and gas potential of the Pechora Sea offshore were delineated, basing on the Timan-Pechora oil and gas potential analysis. These are the northwest extensions into the Pechora Sea of the Denisov trough, the Kolva megaswell, as well as the Varandei-Adzva structural zone and the Karotaiha depression. Keywords: natural reservoir; genuine seal; false seal; field; pool; hydrocarbons.

Characteristic of Tuwayil Formation and New Insight into its Contribution in Middle Cretaceous Petroleum System, Western UAE

In Western UAE, the Middle Cretaceous petroleum system is composed of Shilaif source, Mishrif/Tuwayil reservoir and Tuwayil/Ruwaydha seal. Oil is discovered in Tuwayil sandstone in DH and NN fields. Well correlation of Tuwayil siliciclastic interval shows high heterogeneity and rapid lithology varies. Currently, a few general studies about Tuwayil sandstone was published. However, detailed sedimentary facies, reservoir characteristics and accumulation mechanism about Tuwayil are ambiguous. Limitation on these aspects prohibits enlarging exploration activity of Tuwayil and makes barriers to deepen understanding of the whole K2 PS. To enhance understanding on Tuwayil formation, well data in DH, NN fields and adjacent area was integrated. Dedicated single well analysis, well correlation and petrophysics study were carried out. Cores were observed and laboratory outcomes including TS, SEM, RCA, MICP, XRD were adopted into this study. Furthermore, we have also utilized 2D&3D seismic to illustrate the spatial distribution of Tuwayil siliciclastic setting and interior sediment pattern. Basically, the Tuwayil sand-shale interval represents the infilling of Mishrif/Shilaif intrashelf basin and mainly deposits in the tidal flat-delta facies. The epi-continental clast is sourced from the Arabian shield and transferred from west to east. In Western UAE, the Tuwayil depocenter located in DH field, where 4-5 sand layers deposit with net pay of 30-40ft. In NN field, only one sand layer develops with net pay about 4-6ft. Through deposition cycles identification and seismic reflection observation, two sand groups could be recognized in this interval. The lower group is constrained in the depocenter and influenced by the paleo-geomorphology background. The upper group overpassed the former set and pinched out around north of NN. The Mishrif/Shilaif slope area is another potential belt to enlarge Tuwayil discovery, where stratigraphic onlap could be observed and it probably represents the sand pinch-out in lower sand group. For the K2 PS, previous study believed the shale between Tuwayil sand and Mishrif separate these two reservoirs and works as cap rock for Mishrif grainstone. This study suggests that this shale is too thin and not continuous enough to hold the hydrocarbon in Mishrif. On that note, Tuwayil sand and Mishrif belong to the same petroleum system in NN and may have the same OWC. In the NN field, it is quite crucial to consider the extension of Tuwayil sand during evaluating the stratigraphic prospect of Mishrif because the hydrocarbon is mostly likely charged Tuwayil sand first and then gets into underlain Mishrif. This study provides updates and understandings on sedimentary facies, depositional pattern, hydrocarbon accumulation mechanism, reservoir extension and potential identification of Tuwayil formation, which has inspiring implications for the whole K2 PS and could also de-risk the further exploration activity in Western UAE.

How a stream can change a city

<p>The motivation of this thesis is to generate an understanding of how cities can begin to shift towards pedestrian friendly centres for activity. Introducing streams into urban environments through the process of daylighting can generate public life, improve sustainability, and enable growth. Daylighting is the process of bringing a stream back to the surface into a more natural state. By ensuring the stream is used as the core driver for strategic change, development can occur on the edges of the stream as a decentralised hub for activity and movement within the public realm. The stream as a public element can connect people and create active stakeholders within urban communities as the contributors to the vibrancy of the city. Daylighting can be the catalyst to revitalise Wellington and demonstrate that urban environments are not confined to the existing structure of the city when reintegrating natural elements. Pedestrian activity along stream edges can act as a central mode of urban life, complementing Wellington’s existing waterfront. Generating public space around water as a central hub can connect people to social spaces that the city has previously turned from in favour of roads. Establishing dominant pedestrian areas located around a daylighted stream enables public space to prioritise activity over movement and allows infrastructure to prioritise people over vehicles. From hills to harbour, water can be used as a design tool, generating a language that can activate urban environments. In developing the stream’s framework, it is important that the first considerations take regard of the direction and flow of the water’s path. The directionality of the stream should have the greatest benefit to the affected stakeholders to ensure the stream positively contributes to the qualities of the city. This contribution is essential for the people that work or live adjacent to the new infrastructure, as they will occupy the new space most frequently. Viability of the stream is dependent on the path it takes through the city, as this affects which landowners will be included in the project. Old or small structures, empty sites such as car parks, or roadways with limited vehicle movement could provide the greatest opportunity for development within the city. These should be considered fundamental to the implementation of the stream as they mitigate the changes to the affected stakeholders and benefit other members within the adjacent area.</p>

How a stream can change a city

<p>The motivation of this thesis is to generate an understanding of how cities can begin to shift towards pedestrian friendly centres for activity. Introducing streams into urban environments through the process of daylighting can generate public life, improve sustainability, and enable growth. Daylighting is the process of bringing a stream back to the surface into a more natural state. By ensuring the stream is used as the core driver for strategic change, development can occur on the edges of the stream as a decentralised hub for activity and movement within the public realm. The stream as a public element can connect people and create active stakeholders within urban communities as the contributors to the vibrancy of the city. Daylighting can be the catalyst to revitalise Wellington and demonstrate that urban environments are not confined to the existing structure of the city when reintegrating natural elements. Pedestrian activity along stream edges can act as a central mode of urban life, complementing Wellington’s existing waterfront. Generating public space around water as a central hub can connect people to social spaces that the city has previously turned from in favour of roads. Establishing dominant pedestrian areas located around a daylighted stream enables public space to prioritise activity over movement and allows infrastructure to prioritise people over vehicles. From hills to harbour, water can be used as a design tool, generating a language that can activate urban environments. In developing the stream’s framework, it is important that the first considerations take regard of the direction and flow of the water’s path. The directionality of the stream should have the greatest benefit to the affected stakeholders to ensure the stream positively contributes to the qualities of the city. This contribution is essential for the people that work or live adjacent to the new infrastructure, as they will occupy the new space most frequently. Viability of the stream is dependent on the path it takes through the city, as this affects which landowners will be included in the project. Old or small structures, empty sites such as car parks, or roadways with limited vehicle movement could provide the greatest opportunity for development within the city. These should be considered fundamental to the implementation of the stream as they mitigate the changes to the affected stakeholders and benefit other members within the adjacent area.</p>