Oceanologia No. 65 (4) / 23

Contents

Original research article

Original research article


The influence of biochemical parameters on primary production in the Gulf of Gdańsk region: A model study
Oceanologia 2023, 65(4), 517-533
https://doi.org/10.1016/j.oceano.2023.05.001

Maciej Janecki*, Dawid Dybowski, Lidia Dzierzbicka-Głowacka
Ecohydrodynamics Laboratory, Physical Oceanography Department, Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland;
e-mail: mjanecki@iopan.pl, ddybowski@iopan.pl, dzierzb@iopan.pl
*corresponding author

keywords: Gulf of Gdańsk, Biochemical parameters, Primary production, Phytoplankton, Numerical modelling

Received 31 March 2023, Revised 22 May 2023, Accepted 23 May 2023, Available online 7 June 2023, Version of Record 4 September 2023.

Abstract

Understanding the changing levels of biochemical parameters and the factors that influence them throughout the seasons is crucial for comprehending the dynamics of marine ecosystems. It also helps us identify potential threats that could harm their condition, aiding decision-making processes related to their protection. This study focuses on examining the variations in nutrients (such as nitrates, phosphates, and silicates), dissolved oxygen, and phytoplankton within the Gulf of Gdańsk. Additionally, we analyze the primary production process at three representative locations. To achieve this, we used data from the EcoFish biochemical numerical model. To ensure the model's accuracy, we compared its results with in situ data from the ICES database. The comparison revealed high correlations and minimal errors. Furthermore, we investigated how limiting factors impact primary phytoplankton production and demonstrated how the intensity of spring diatom blooms influences the nature of cyanobacterial blooms in the summer.
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Projections of wind climate and wave energy resources in Lithuanian territorial waters of the Baltic Sea in the 21st century
Oceanologia 2023, 65(4), 534-547
https://doi.org/10.1016/j.oceano.2023.06.004

Darius Jakimavičius*, Vytautas Akstinas
Laboratory of Hydrology, Lithuanian Energy Institute, Kaunas, Lithuania;
e-mail: darius.jakimavicius@lei.lt, vytautas.akstinas@lei.lt
*corresponding author

keywords: Wave energy flux, Baltic Sea, Wind projections, Wave height, SSP scenarios

Received 15 September 2022, Revised 2 June 2023, Accepted 9 June 2023, Available online 24 June 2023, Version of Record 4 September 2023.

Abstract

Wave energy is still insufficiently explored and exploited as a future energy source. Climate change is an additional force that affects energy potential changes. Therefore, this study aims to evaluate the wave energy under climate change and to project it for the near (2025–2044) and far (2081–2100) future by applying the wave energy flux (WEF) approach and statistical relations between wind speeds and wave heights. The study was concentrated on the Baltic Sea nearshore at the Lithuanian territorial water. The analysis of existing relations between wind speeds and wave heights was found based on historical observations of the reference period (1995–2014), and the projections of WEF were created using the downscaled output of best-fit global climate models (GCMs) according to four scenarios of Shared Socioeconomic Pathways (SSP). The results indicated strong relations between wind speed and wave height, especially for the west-origin winds. Depending on the selected scenarios, the projected WEF may increase up to 10% (SSP5-8.5) and 11% (SSP1-2.6) in the near and far future respectively. The absence of large differences between the periods may be caused by the rough resolution of grid cells of GCMs. The comparison with the results based on regional climate models output could be a future perspective in order to reach a better representation of regional forces and to introduce more clarity to the obtained results. The results of this study may be advantageous for the primary planning of renewable energy sources (RES) development, especially in the face of climate change.
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Stripe segmentation of oceanic internal waves in SAR images based on Gabor transform and K-means clustering
Oceanologia 2023, 65(4), 548-555
https://doi.org/10.1016/j.oceano.2023.06.006

Kai-Tuo Qi1, Hong-Sheng Zhang1, Ying-Gang Zheng2, Yu Zhang3,*, Long-Yu Ding1
1College of Ocean Science and Engineering, Shanghai Maritime University, Shanghai, China;
e-mail: 2932366338@qq.com, hszhang@shmtu.edu.cn, 1938556272@qq.com
2Translational Research Institute of Brain and Brain-Like Intelligence, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai, China;
e-mail: ingopro@qq.com
3College of Harbour, Coastal and Offshore Engineering, Hohai University, Nanjing, China;
e-mail: jessicazhang@hhu.edu.cn
*corresponding author

keywords: Oceanic internal waves, Synthetic aperture radar, Gabor transform, K-means clustering, Stripe segmentation

Received 9 September 2022, Revised 5 June 2023, Accepted 9 June 2023, Available online 24 June 2023, Version of Record 4 September 2023.

Abstract

Oceanic internal waves are an active ocean phenomenon that can be observed, and their relevant characteristics can be acquired using synthetic aperture radar (SAR). The locations of oceanic internal waves must be determined first to obtain the important parameters of oceanic internal waves from SAR images. An oceanic internal wave segmentation method with integrated light and dark stripes was described in this study. To extract the SAR image characteristics of oceanic internal waves, the Gabor transform was initially used, and then the K-means clustering algorithm was used to separate the light (dark) stripes of oceanic internal waves from the background in the SAR images. The regions of the dark (light) stripes were automatically determined based on the differences between the three classes, that is, the dark stripes, light stripes, and background area. Finally, the locations of the dark (light) stripes were determined by shifting a given distance along the normal direction of the long side with the minimum bounding rectangle of the light (dark) stripes. The best segmentation results were obtained based on the intersection over the union of the images, and the accuracy of segmentation was verified. Furthermore, the effectiveness and practicability of the proposed method in the light and dark stripe segmentation of SAR images of oceanic internal waves were illustrated. The proposed method prepares the foundation for future inversion studies of oceanic internal waves.
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Modified logarithmic distribution of wind-driven flow velocity in remote foreshore of the non-tidal sea
Oceanologia 2023, 65(4), 556-563
https://doi.org/10.1016/j.oceano.2023.06.003

Rafał Ostrowski, Magdalena Stella-Bogusz*
Institute of Hydro-Engineering, Polish Academy of Sciences, Gdańsk, Poland;
e-mail: m.stella@ibwpan.gda.pl
*corresponding author

keywords: Wave-induced nearbed velocities, Wind-driven current, Bed shear stresses, Modified logarithmic velocity distribution

Received 18 November 2022, Revised 30 May 2023, Accepted 9 June 2023, Available online 20 June 2023, Version of Record 4 September 2023.

Abstract

The paper presents the results of the novel modelling of the wind-driven current in the southern Baltic Sea. The steady current is accompanied by wave-induced orbital velocities. The bed boundary layer related to wave-induced oscillatory flow gives rise to the appearance of additional shear stresses affecting the wind-driven current. This impact included in the wind-driven current model yields a modified logarithmic velocity distribution. Theoretical velocity profiles are compared with the field data. The measurement database includes wind, wave and current parameters. The velocities and directions of the wind were collected from the anemometer installed at the Coastal Research Station (CRS) in Lubiatowo. Wave-current parameters at a depth of about 17 m were obtained from a location of approx. 1.5 Nm from the shoreline in the vicinity of CRS Lubiatowo. The study site hydrodynamics is typical of the south Baltic coast. The analysis shows good agreement between the measured flow velocities and the theoretical vertical distributions in the form of the modified logarithmic profile.
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Excitation of an extreme wave by standing current
Oceanologia 2023, 65(4), 564-570
https://doi.org/10.1016/j.oceano.2023.06.005

Pavlo Anakhov
Department of Infrastructure Systems, National Power Company "Ukrenergo", Kyiv, Ukraine;
e-mail: ramesh.madipally@ncess.gov.in

keywords: Damping of oscillations, Excitation of oscillations, Standing current, Standing wave, Sustaining of oscillations

Received 19 October 2022, Revised 12 June 2023, Accepted 12 June 2023, Available online 23 June 2023, Version of Record 4 September 2023.

Abstract

The statistics suggest that extreme waves cause more damage in shallow waters and at the coast than in the deep sea. In the linear theory of the formation of extreme waves, their existence is interpreted as a local superposition of surface monochromatic waves. The event of excitation of extreme waves can be understood as an increase in natural oscillations of the water basin. The conditions for the excitation and sustaining of natural oscillations are the proximity of the periods of exciting traveling waves to the period of traveling waves and the speed of movement of the exciting current to the phase speed of propagation of traveling waves of the reservoir. Examples of stimulating natural oscillations are presented. We determined the range of expected periods of natural oscillations, which range from 30 seconds to 24 hours. Synchronously and in common-mode with the oscillations of standing waves between their antinodes, a "standing" current occurs with a measured speed of up to 11 km/h. We presented a hypothesis about the possibility of stimulating natural oscillations of water bodies by a standing current, which changes its direction due to the movement of the water surface from the trough of the wave to its crest, and back. A model of stimulating oscillations by the waves with a constant period and currents with constant and variable speeds has been developed.
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Dinoflagellate cysts and benthic foraminifera from surface sediments of Svalbard fjords and shelves as paleoenvironmental indicators
Oceanologia 2023, 65(4), 571-594
https://doi.org/10.1016/j.oceano.2023.06.007

Maciej M. Telesiński1,*, Vera Pospelova2, Kenneth Neil Mertens3, Małgorzata Kucharska1, Marek Zajączkowski1
1Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland;
e-mail: mtelesinski@iopan.pl
2University of Minnesota, Department of Earth and Environmental Sciences, College of Science & Engineering, Minneapolis, USA
3LITTORAL, Ifremer, Concarneau, France
*corresponding author

keywords: North Atlantic, Nordic Seas, Sea ice, Primary productivity, Fjords, Sediments, Chlorophyll-a

Received 6 October 2022, Revised 7 June 2023, Accepted 14 June 2023, Available online 28 June 2023, Version of Record 4 September 2023.

Abstract

Due to the Arctic amplification effect, the Svalbard archipelago is an important area for studying ongoing environmental changes. However, its marine ecosystem is extremely complex. In this study, we analyze modern assemblages of dinoflagellate cysts (dinocysts) and benthic foraminifera from surface sediment samples around Svalbard. We use multivariate statistical analyses to examine relationships between environmental conditions (summer and winter sea surface temperature and salinity, sea-ice cover, etc.) and both microfossil groups to evaluate their use as proxies for reconstructions of the marine environment in the region. Our results show that the most important factor controlling the environment around Svalbard is the Atlantic Water which mostly impacts the western coast, but its influence reaches as far as the eastern coast of Nordaustlandet. However, on a local scale, such factors as the sea-ice cover, the presence of tidewater glaciers, or even the morphology and hydrology of fjords become increasingly important. We found that two dinocyst species, cysts of Polarella glacialis and Echinidinium karaense, can be considered regional winter drift ice indicators. The relationships between environmental parameters and benthic foraminiferal assemblages are much more difficult to interpret. Although statistical analysis shows a correlation of benthic foraminiferal species with various environmental parameters, this correlation might be somewhat coincidental and caused by other factors not analyzed in this study. Nevertheless, the use of two complementary microfossil groups as (paleo)environmental indicators can provide a more comprehensive picture of the environmental conditions.
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Assessment of human interventions presence and their impact on shoreline changes along Nile delta, Egypt
Oceanologia 2023, 65(4), 595-611
https://doi.org/10.1016/j.oceano.2023.06.008

May R. ElKotby1,*, Tharwat A. Sarhan2, Mahmoud El-Gamal3
1Irrigation and Hydraulics Engineering Department, Mansoura University, Mansoura, Egypt;
e-mail: may_ramdan@mans.edu.eg
2Harbor and Coastal Engineering, Mansoura University, Mansoura, Egypt;
e-mail: prof_tharwat@mans.edu.eg
3Water structure, Mansoura University, Mansoura, Egypt;
e-mail: Mmelgamel@hotmail.com
*corresponding author

keywords: Shoreline changes, Nile Delta, Landsat image, DSAS software, LRR model

Received 25 December 2022, Revised 8 June 2023, Accepted 14 June 2023, Available online 8 July 2023, Version of Record 4 September 2023.

Abstract

Coastal erosion is a natural process, that contributed to shaping the Nile Delta shoreline in Egypt over history. The objective of this research is to investigate shoreline changes, accretion, and erosion and to detect particularly vulnerable locations that require immediate attention. Another goal is to assess the efficiency of coastal installations that have been recently implemented along the study area and determine whether they have performed their role to the fullest or need additional modifications. Several Landsat images (TM, ETM+, and OLI) were utilized over 37 years to track the shoreline changes and were analysed using remote sensing (RS) and Geographic Information System (GIS). The digital shoreline analysis system (DSAS) was integrated with the LRR model for assessing historical changes for shorelines from 1985 to 2022 and forecasting future shoreline positions in 2030, 2050, and 2100. Most of the eight zones that make up the Delta region have lately seen the establishment of coastal projects, such as the development of the Abu Qir port's breakwater in 2021. From the results, it was found that the areas around Rosetta promontory, Burullus headland, and Damietta promontory experienced a significant and rapid retreat and with large rates over the study period, with average values of –15.7, –3.25, and –16.8 m/y, respectively. However, both the coast of Alexandria, and Gamasa embayment were subjected to accretion as a prevailing case, with average rates of 2.85, and 4.03 m/y, respectively. Many groins were installed in the east of the Rosetta promontory (zone 3) in 2016 to decrease the erosion process; however, it didn't pay off and could not solve the problem. In contrast, the groins system, which was implemented at the East Kitchener Drain (zone 5) in the same year, lowered erosion rates from 17.6 m/y from 2000 to 2010 to 7 m/y from 2010 to 2022. In 2019, Y-groins built in zone 7, east of Damietta Port, succeeded in slowing rates of erosion. Finally, inlet jetties at El-Gamil (zone 8) were constructed in 2016, resulting in the coastline advancing at 14.7 m/y on average in the period of 2010–2022. The findings of this study confirmed that hard structures are dangerous because they exacerbate the problem of shoreline erosion by disseminating it to the neighbouring beaches and acting as an impediment to the movement of longshore sediments. According to the expected future shoreline patterns, it is necessary for authorities to implement both short-term and long-term protective measures to stop the erosion of several areas of the beach.
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First survey of metallic distribution in zooplankton from a south Moroccan area
Oceanologia 2023, 65(4), 612-623
https://doi.org/10.1016/j.oceano.2023.06.009

Fatima Zohra Bouthir1,*, Imane Afandi1, Sophia Talba2, Maylis Labonne3, Hicham Masski1, Mathieu Waeles4, Raymond Lae4
1National Institute of Fisheries Research (INRH), Casablanca, Morocco;
e-mail: fzbouthir@gmail.com, afandi.imane@gmail.com, hmasski@gmail.com
2Faculty of Sciences Ben M'sik, Casablanca, Morocco;
e-mail: sophia.talba@gmail.com
3UMR MARBEC, University of Montpellier, Montpellier, France;
e-mail: Maylis.Labonne@ird.fr
4UMR LEMAR 6539, European Institute For Marine Studies, Plouzané, Brest, France;
e-mail: Matthieu.Waeles@univ-brest.fr, raymond.lae@ird.fr
*corresponding author

keywords: Zooplankton, Metals, Southern Atlantic coast of Morocco, Upwelling, EPURE cruises

Received 17 June 2022, Revised 16 June 2023, Accepted 30 June 2023, Available online 11 July 2023, Version of Record 4 September 2023.

Abstract

The Moroccan Southern Atlantic coast is mainly influenced by upwelling, Saharan dust and anthropogenic micropollutant input. These factors contribute to increasing the availability of metal elements in waters. To differentiate human impact from natural variability, knowledge of background concentrations of metals and their fluctuations in bioindicator organisms such as zooplankton is important. This work aims to determine the levels of metals elements (Zn, Mn, Pb, Cu, Cd, Cr, Co, Ni, Li, As, Sr, U, Fe and Ba) in zooplankton along the southern area of the Atlantic coast of Morocco. Zooplankton samples were collected in the summer (July 2013) and autumn (December 2013) at 27 stations from Sidi Ifni to the south of Dakhla. All stations were located on transects perpendicular to the coast. The analysis of metal elements in zooplankton was determined by ICP–MS. The results revealed that in all transects, metal concentrations were below the regulatory limits. Metal enrichments were observed in the south and decreased gradually to the north. This study can be used as baseline data for the metal contents of zooplankton in Moroccan South Atlantic coastal water. A comparison to worldwide reported data on zooplankton did not reveal any suggestions on increased metal presence in the area investigated.
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