Science and earth science

Oceanologia

Content

Oceanologia | 2025 | Vol. 67 | No 2

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Abstract

The dynamics of the Banda Sea can influence larger-scale oceanic processes and contribute to the global ocean circulation system. This research aims to utilize data from a global in situ data repository spanning the years 1960 to 2018, along with data collected from 12 stations during the recent Jalacitra II-2022 expedition. The focus is on analyzing salinity and potential temperature data to construct water mass features, including seasonal temperature-salinity-time diagrams and water column stability using Brunt Vaisala Frequency. Thorpe analysis is employed to investigate turbulent mixing within the region. The results found that temperatures are notably lower in Northwest Monsoon (NWM), reaching 30.0°C, while Southeast Monsoon (SEM) temperatures hover around 28.0°C. Salinity profiles reveal that SEM generally exhibits lower salinity levels, ranging from 33.5 to 34.4, compared to NWM, which ranges from 34.0 to 34.5. Vertical profiles of temperature and salinity variations in the SEM display a more varied thermocline layer depth than NWM. Data from the JC II expedition in the Banda Sea revealed a slight temperature decrease from 27.5°C to 26°C in August, accompanied by salinity variations. Surface salinity was measured at 33.3, while a uniform salinity of 34.6 was observed from 100 meters downward during the same period. This study identifies five dominant water mass types in the Banda Sea, primarily from the Pacific Ocean, which are North Pacific Intermediate Water (NPIW) and North Pacific Subtropical Water (NPSW). During the NWM season, water column instability occurs at depths up to 200 meters, while deeper water column instability is observed during the SEM, extending to a depth of 300 meters, with stability values lower than four cycles/hour. Furthermore, high turbulence generally occurs in the thermocline layer (50 to 300 m).
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Authors and Affiliations

Noir P. Purba
1 2
Noor C.D. Aryanto
2 3
Hendra K. Febriawan
4
Adam B. Nugroho
5
Mohd Fadzil Akhir
6
Afifi Johari
6
Syawaludin A. Harahap
1
Ghelby M. Faid
7
Muhammad H. Ilmi
7
Anom P. Hascaryo
8
Dyan P. Sobaruddin
8
Candrasa S. Dharma
8
Budi Muljana
9
Cipta Endyana
9

  1. Department of Marine Science, Padjadjaran University, Bandung, Indonesia
  2. Indonesia National Committee, Intergovernmental Oceanographic Commission (IOC) – UNESCO, Jakarta, Indonesia
  3. Research Centre for Geological Resources, National Research and Innovation Agency (BRIN), Jakarta, Indonesia
  4. Directorate of Research Vessel Management, National Research and Innovation Agency (BRIN), Jakarta, Indonesia
  5. Research Centre for Geological Disaster, National Research and Innovation Agency (BRIN), Jakarta, Indonesia
  6. Institute of Oceanography and Environment, University Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia
  7. KomitmenX Research Group, Padjadjaran University, Bandung, Indonesia
  8. Centre for Hydro-Oceanography, Indonesian Navy, Jakarta, Indonesia
  9. Department of Geology, Padjadjaran University, Bandung, Indonesia
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Abstract

This study examines sea level observations along the Polish coast from 1995 to 2019, combining in situ measurements from tide gauge stations with radar satellite altimetry data. The research is driven by developing new satellite products under the Baltic + SEAL project, specifically tailored for the Baltic Sea. These innovative products utilise advanced algorithms for sea level estimation, enhanced radar waveform processing, and high-resolution sea level data collected in Synthetic Aperture Radar (SAR) mode by multiple satellites during the analysed period. The study’s primary aim is to validate and assess the performance of the Baltic + SEAL product against the standard sea level data provided by the Copernicus Marine Environment Monitoring Service (CMEMS) and observations from nine tide gauges distributed along the Polish coast. The evaluation focuses on long-term trends, seasonal variations, and statistical metrics across various time scales, from daily to decadal. The results underscore both the strengths and limitations of the Baltic + SEAL product in capturing spatial and temporal variations in sea levels. This study contributes valuable insights into sea level change dynamics along the Polish coast, providing essential information for coastal monitoring, management, and future research in the Baltic Sea region.
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Authors and Affiliations

Anna Izabela Bulczak
1
Beata Kowalska
2
Lidia Dzierzbicka-Głowacka
1

  1. Institute of Oceanology, Polish Academy of Sciences, Powstańców Warszawy 55, 81–712 Sopot, Poland
  2. Instytut Meteorologii i Gospodarki Wodnej, Jerzego Waszyngtona 42, 81–342, Gdynia, Poland
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Abstract

The distribution of fish orientation is a very important factor influencing their Target Strength (TS), and thus the hydroacoustic assessment of fish abundance. A technique has been developed to estimate the orientation distribution of aggregated Baltic herring (Clupea harengus) by fitting the TS histograms obtained from the theoretical backscattering model to the measured TS histograms. By using available morphometry data of Baltic herring, a modified resonance scattering model to describe the backscattering by Baltic herring has been developed. Using this model, TS histograms were generated for different probability density functions (PDFs) of fish orientation, and then compared with the measured TS histograms. Based on the best fit to the measured histograms, the most likely distribution of herring orientation can be inferred.
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Authors and Affiliations

Aleksander Żytko
1
Natalia Gorska
1
Dezhang Chu
2
Beata Schmidt
3

  1. Institute of Oceanology, Polish Academy of Sciences, Powstańców Warszawy 55, 81–712 Sopot, Poland
  2. NOAA Fisheries, Northwest Fisheries Science Center, 2725 Montlake Blvd. E., Seattle, WA 98112, USA
  3. National Marine Fisheries Research Institute, ul. Kołłątaja 1, 81–332 Gdynia, Poland
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Abstract

It is necessary to know the climatic conditions and classes in order to address a region’s climate-related problems and ensure its sustainability. Kozlu, located on the Black Sea coast in the Black Sea region of Turkey, is a district where underground mining, fishing, sea tourism and agricultural activities are conducted. The district faces challenges due to geo-environmental factors, including landslides, subsidence, and floods, necessitating the identification of climate classes and characteristics to support sustainable development. For this reason, data for the last thirty years from four meteorological stations representing the Kozlu district were obtained. It was associated with the location, and then the Kriging interpolation method was applied. After this, water balances were calculated by applying the Thornthwaite climate classification method, and GIS-based climate boundary maps were generated using the same method. In the climate classification made by the Thornthwaite method, it was observed that the humid climate characteristic was dominant throughout the district. The drought index indicates moderate summer water deficiency in the north and the south of the district. In the south of the district, it is characterized by little or no water deficiency. Considering that the annual precipitation amounts at the stations located in the south of the district are higher than in the other areas, and the time interval in which water deficiency occurs is shorter, the fact that the climate feature of little or no water deficiency is seen moving south in the study area shows that the results are quite compatible with each other. In addition, according to the results of the summer concentration index, the entire study area was observed to be dominated by a marine climate. Climate boundary maps consisting of precipitation efficiency, temperature efficiency, drought and summer concentration index maps will contribute to monitoring climate change in the district.
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Authors and Affiliations

Hulya Keskin Citiroglu
1
Deniz Arca
2

  1. Directorate of Aydın Investment Monitoring and Coordination, Aydın YIKOB, Aydın, Turkey
  2. Department of Architecture and Urban Planning, Izmir Vocational School, Dokuz Eylul University, Izmir, Turkey
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Abstract

Within the coastal flow-field system, the hydrodynamic coupling between the tidal channel and surf zone is among the most important, implicated in shoreline morphodynamics, river mouth bar dynamics, and the recreational quality of nearshore waters. The nature of the coupling has seldom been empirically evaluated at tidal frequencies spanning lunar cycles. This investigation is directed at filling this gap in information based on 50-day successive tidal cycle flow monitoring in an estuary–surf zone setting, S. E. coast of Nigeria. Results show a reversing flow pattern at all monitoring stations at tidal frequencies. The estuary indicated ebb-asymmetric tidal cycle residual flow velocities which at spring tide (30–38 cm/s range) act as an expanding jet relative to the flanking surf zone residual longshore current counterparts (typically ≤ 5 cm/s). The western and eastern flanking surf zones showed westward- and eastward-asymmetric tidal cycle residual flows, respectively with coastwise decreasing asymmetry reflecting the weakening impact of the estuary outflow. Coupling of surf zone – estuarine residual flow vectors indicated a higher frequency of threshold coefficient (r ≥ 0.7) at ebb than at flood stage. The observed pattern of strong estuarine residual outflow velocities and modally divergent weak surf zone flows is a favourable condition for the estuary mouth bar development. However, the eastward-skewed bar configuration fits more to the effect of eastward-directed momentum flux associated with water mass transport of the obliquely-shoaling southwesterly waves given that breaking wave-generated longshore currents in the western surf zone display a westward-asymmetry over a tidal cycle.
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Authors and Affiliations

Effiom E. Antia
1

  1. Department of Physical Oceanography, Faculty of Oceanography, University of Calabar, PMB 1115 Calabar, Cross River State, Nigeria
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Abstract

This case study advocates a generic state-of-the-art multidimensional natural hazards evaluation methodology, applied to windspeeds and wave heights, measured in different offshore locations. Due to complex nonlinear spatiotemporal crosscorrelations between different environmental system components and covariates, it is challenging to assess associated environmental risks, utilizing existing reliability techniques. Hence, it is necessary to develop novel multimodal reliability and risk assessment methods for natural hazards prognostics further, given global climate variability. Advocated multivariate risk assessment methodology being particularly suitable for both environmental and offshore/ocean structural systems, which have been either physically measured or numerically simulated over a representative period. National Oceanic and Atmospheric Administration (NOAA) buoys, operating in the central Bering Sea, provided the raw in situ measurements of windspeeds and wave heights, utilized in this case study. A relatively limited amount of underlying data had been analyzed – only 4 months between June and September 2024. The presented multimodal natural hazards prognostics methodology has a generic nature, hence, large amounts of measured data can be analyzed if available. A novel non-parametric deconvolution extrapolation scheme has been utilized to accurately forecast in situ extreme environmental climate dynamics events. System’s quasi-stationarity was assumed; otherwise, for nonstationary multidimensional dynamic systems with underlying multivariate trend, this trend has to be identified first, before the advocated reliability methodology to be applied. Distinct advantage of presented multivariate reliability methodology versus existing ones lies within its ability to overcome “curse of dimensionality”, namely ability to treat systems with dimensionality above two.
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Authors and Affiliations

Alia Ashraf
1
Oleg Gaidai
1
Jinlu Sheng
2
Yan Zhu
3
Zirui Liu
1

  1. Shanghai Ocean University, Shanghai, China
  2. Chongqing Jiao Tong University, Chongqing, China
  3. Jiangsu University of Science and Technology, Zhenjiang, China
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Abstract

Shorelines are vital and dynamic components of the coastal zone, constantly changing due to various environmental factors. These areas hold significant recreational, economic, and ecological importance, making the understanding of shoreline alterations critical. Unlike open oceans, the Caspian Sea (CS) has experienced a noticeable decline in water level since the late 1990s due to a combination of climatic variability, reduced riverine inflow, increased evaporation, and anthropogenic factors. This decline in water level is expected to drive morphological changes in the shorelines, with an overall trend of shorelines retreating seaward. In this study, the shoreline changes of Ogurja Island, the largest island in the CS, were analyzed using Sentinel-2 satellite imagery from 2015 to 2023, covering a total of 9 images, and the Digital Shoreline Analysis System tool. The study aimed to establish a relationship between these shoreline changes and the decline in the Caspian Sea water level (CSL). The results reveal a strong correlation, with shoreline movements reaching up to 80 m/year in some areas, and significant changes are expected with the projected CSL decline. This research offers an initial attempt to connect shoreline dynamics with water level fluctuations, highlighting the importance of considering shoreline changes in future water level predictions. The study recommends that future research focus on integrating advanced models, such as hydrodynamic simulations and machine learning techniques, to refine shoreline predictions and enhance understanding of the CS’s dynamic coastal environment.
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Authors and Affiliations

Rahimeh Shamsaie
1
Danial Ghaderi
2 3

  1. Faculty of Marine Science and Technology, University of Hormozgan, Bandar Abbas, Iran
  2. Center Providing Consultation and Simulation Services For Coastal And Marine Environments (NPDS Company), Bandar Abbas, Iran
  3. Physical Oceanography, Shahid Rajaee Port Complex, Ports and Maritime Organization, Bandar Abbas, Iran
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Abstract

This study examines mollusk communities in shallow (< 150 m) and deep (> 200 m) zones of Arctic, sub-Arctic, and temperate fjords to assess macrofaunal blue carbon storage under climate change. Biomass and trait-based analyses show that shallow Arctic habitats support long-lived, large suspension feeders with high carbon storage potential. In contrast, warmer regions host smaller, short-lived taxa, indicating reduced carbon storage and altered climate feedbacks. These findings underscore the vulnerability of existing zoobenthic carbon stocks and highlight the need to expand research to other taxa and full benthic communities across the European Arctic.
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Authors and Affiliations

Marc J. Silberberger
1 2

  1. Department of Fisheries Oceanography and Marine Ecology, National Marine Fisheries Research Institute, Hugo Kołłątaja 1, 81–332 Gdynia, Poland
  2. Institute of Oceanology Polish Academy of Sciences, Powstańców Warszawy 55, 81–712 Sopot, Poland
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Abstract

A common cause of unnatural death in marine organisms is entanglement in derelict fishing gear and other marine debris. Such incidents involving marine birds, mammals, turtles and fish are regularly reported. However, few documented cases of entangled sea snakes (Hydrophiinae) exist. This report details the findings of a dead yellow sea snake (Hydrophis spiralis) in the northwestern Bay of Bengal. The sea snake was found with a section of fishing net mesh constricting its neck, causing damage to the underlying tissue and exposing the muscle. The twine was located anterior to the stomach, and necropsy revealed no food in the stomach or intestines. This is the first recorded case of sea snake mortality due to marine debris entanglement or entrapment in Indian waters.
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Authors and Affiliations

Pratyush Das
1 2 3
Pratap Kumar Mohanty
2
Krishnan Silambarasan
1
Sujit Kumar Pattnayak
1
Gunamaya Patra
3
Digambar Swain
3
Annada Bhusan Kar
1
Rebecca Jade Nicholls
4

  1. Fishery Survey of India, Ministry of Fisheries, Animal Husbandry and Dairying, Government of India, Visakhapatnam, India
  2. Department of Marine Sciences, Berhampur University, Odisha, India
  3. Department of Fisheries, Ministry of Fisheries, Animal Husbandry and Dairying, New Delhi – 110001
  4. Thomson Environmental Consultants, Compass House, Surrey Research Park, Guildford, GU2 7AG, United Kingdom

Authors and Affiliations

Dag Myrhaug
1

  1. Department of Marine Technology, Norwegian University of Science and Technology (NTNU), Trondheim, Norway

Instructions for authors

INTRODUCTION

Criteria for manuscripts

The Editorial Board of Oceanologia takes under consideration for publication original articles with the understanding that neither the manuscript nor any part of its essential substance, tables or figures have been published previously in print form or electronically and are not under consideration by any other publication or electronic medium. Copies of any closely related manuscripts should be submitted to the Editor along with the manuscript that is to be considered by Oceanologia. Each submission packet should include the statement signed by the first author that the work has not been published previously or submitted elsewhere for review and a copyright transfer.

The journal Oceanologia publishes original papers on fundamental aspects of marine research with the emphasis on northern European seas. Papers dealing with processes in the marine environment are preferred to purely descriptive ones; they should contribute to the understanding of the functioning of marine ecosystems, including their abiotic aspects. Please note that purely descriptive articles/ papers do not meet the aims of Oceanologia. All scripts received will be reviewed by the editors and at least two independent experts. The scripts should be written in good, scientific English: American or British. Every effort will be made to expedite publication.

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No charges will be imposed for papers up to 20 pages long including figures, tables and references (some 40 pages of typescript, double spaced, including references, tables, figures and appendicies). For longer articles please contact hte editorial office at oceano@elsevier.com.

For papers exceeding 20 pages, an excess-page charge per printed page will be made: 50 EUR net for pages 21 et seq. The author(s) will be informed whether or not his/her/their paper has been accepted for printing and will be billed for the excess-page charge (if any).

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