Oceanologia No. 64 (1 / 22)


Contents


Original research article


Short communication


Original research article



Striped texture of submesoscale fields in the northeastern Baltic Proper: Results of very high-resolution modelling for summer season
Oceanologia 2022, 64(1), 1-21
https://doi.org/10.1016/j.oceano.2021.08.003

Victor Zhurbas1, Germo Väli2,*, Natalia Kuzmina1
1Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia
2Tallinn University of Technology, Tallinn, Estonia;
e-mail: germo.vali@taltech.ee
*corresponding author

keywords: Baltic Sea, Elongated submesoscale structures — stripes, Modelling, Symmetric instability, McIntyre instability, Frontogenesis, Stirring

Received 22 May 2021, Revised 10 August 2021, Accepted 17 August 2021, Available online 28 August 2021, Version of Record 11 February 2022.

Abstract

Very high-resolution modelling of the northeastern Baltic Proper shows that preferentially elongated along the flow, submesoscale inhomogeneities of hydrodynamic fields or stripes of the order of 10–20 km in length and 1 km in width, are typical for summer season both in surface mixed layer and for interior layers which are not directly exposed to atmospheric forcing. In surface layer, the presence of stripes is supported by the remote sensing imagery and their vertical extension is comparable with the mixed layer depth (approx. 5–8 m). In the interior layers, the vertical extension of stripes is considerably larger (approx. 10–50 m) and their slopes exceed the isopycnal slope. Four competitive mechanisms of formation of the mesoscale striped texture are considered: stirring of large-scale inhomogeneities by the eddy field, the classic, inviscid adiabatic fluid symmetric instability, the McIntyre instability, and the strain-induced frontogenesis. Based on the instability criteria and the growth rates and geometry of the disturbances, the classic symmetric instability and the strain-induced frontogenesis are probably responsible for the formation of submesoscale striped texture in the surface layer, while in the interior layers, the strain-induced frontogenesis and hypothetically the McIntyre instability can be essential. Stirring of large-scale inhomogeneities by the eddy field could be responsible for formation of striped texture in a passive tracer concentration and in temperature and salinity in the presence of thermohaline gradients on isopycnic surfaces (thermoclinicity), but it does not imply formation of stripes in dynamically active tracers, such as vertical vorticity, horizontal gradients of buoyancy, etc.
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The process of modelling the elevation surface of a coastal area using the fusion of spatial data from different sensors
Oceanologia 2022, 64(1), 22-34
https://doi.org/10.1016/j.oceano.2021.08.002

Marta Włodarczyk-Sielicka, Izabela Bodus-Olkowska*, Małgorzata Łącka
Maritime University of Szczecin, Szczecin, Poland;
e-mail: i.olkowska@am.szczecin.pl
*corresponding author

keywords: Digital elevation model, Seabed bottom model, Bathymetry, LiDAR data, GEBCO, ETOPO

Received 29 April 2021, Revised 26 July 2021, Accepted 17 August 2021, Available online 28 August 2021, Version of Record 11 February 2022.

Abstract

Information regarding the depth distribution in a specific aquatic area is not also crucial for the safety of navigation, but also for modelling environmental processes, such as the quick establishment of marine-land boundaries or assessments of flood risk areas. Using elevation data from different available sources can be very convenient for individuals who wish to conduct quick analysis or need to obtain data covering a large area without the need for data collection and surveys. This study proposes a method of combining spatial data from different sources during surface modelling of a coastal area. The spatial data used for elevation surface modelling included hydrographic and topographic data, which are often collected separately for various purposes. Data are saved in different formats with various resolutions and accuracies; thus, a uniform surface model that will allow for easy and accurate analysis is currently lacking. The main aim of this study was to create a model of the surface of a coastal area using input data from various sources with the highest possible accuracy. This paper presents the available spatial data sources for coastal areas, along with the data pre-processing process. Furthermore, spatial data fusion is introduced, along with the results. The entire process of creating the uniform surface model consisted of several steps that are described in detail and visualised. The obtained model was visualised using a three-dimensional map.
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A comparative study of biosynthesized marine natural-product nanoparticles as antifouling biocides
Oceanologia 2022, 64(1), 35-49
https://doi.org/10.1016/j.oceano.2021.08.004

Khaled Mahmoud Abdelsalam1,*, Nayrah Aly Shaltout2,*, Hassan Abduallah Ibrahim3,*, Hermine Ramzy Zaki Tadros2,*, Mohamed Abd-Elnaby Aly-Eldeen2,*, Ehab Aly Beltagy3,*
1Taxonomy & Biodiversity of Aquatic Biota Lab, National Institute of Oceanography and Fisheries, NIOF, Cairo, Egypt;
e-mail: kh.abdelsalam@gmail.com
2Marine Chemistry Lab, National Institute of Oceanography and Fisheries, NIOF, Cairo, Egypt;
e-mail: nshaltout@gmail.com, herminetadros@gmail.com, m_niof@yahoo.com
3Microbiology Lab, National Institute of Oceanography and Fisheries, NIOF, Cairo, Egypt;
e-mail: drhassan1973@yahoo.com, ehab.beltagy@gmail.com
*corresponding author

keywords: Antifouling, Nanoparticles, Chitosan, Ulva fasciata, Avicennia marina, leaves

Received 15 December 2020, Revised 19 August 2021, Accepted 21 August 2021, Available online 10 September 2021, Version of Record 11 February 2022.

Abstract

In this study, biosynthesized nanoparticles using chitosan, Ulva fasciata, and Avicennia marina leaves extracts (A, B, and C, respectively), were evaluated as paint additives to control marine fouling on different substrates. These biocidal nanoparticle compounds were prepared using a green biosynthesis method. Their characterizations were conducted using Fourier-Transform Infrared spectroscopy and Transmission electron microscopy. Each nanoparticle compound was mixed with a prepared paint, resulting in three formulations for each (e.g. 1C, 2C, 3C), containing 20%, 40%, and 60% by weight. Painted PVC, wood, and steel with these nine paints, and the control were immersed in seawater for different periods. After two months of immersion, the least number of fouling species, (one species) was recorded on both the wood and steel panels that were coated with paint (1C). Meanwhile, after four months, the least numbers of fouling (four and six species) were recorded on wood and steel panels that were coated with paint (3C). After around seven months of immersion, the least numbers of fouling species (five and ten) were recorded on wood and steel panels that were coated with paints (1C and 3C), respectively. The steel panel coated with (3C), harbored ∼2% of the total number of barnacles found on the control, after 7 months of immersion. The superior antifouling agent efficiency of extract (C) nanoparticles can be attributed to its constituents of polyphenols, ammonium compounds, and high concentrations of alcohols, besides the presence of both aromatic and aliphatic amide and amide derivatives.
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Steric and atmospheric contributions to interannual sea level variability in the eastern mediterranean sea over 1993–2019
Oceanologia 2022, 64(1), 50-62
https://doi.org/10.1016/j.oceano.2021.09.001

Bayoumy Mohamed1,2,*, Nikolaos Skliris3
1University of Alexandria, Faculty of Science, Department of Oceanography, Alexandria, Egypt;
e-mail: m.bayoumy@alexu.edu.eg
2Department of Arctic Geophysics, University Centre in Svalbard, Longyearbyen, Norway;
e-mail: mohamedb@unis.no
3Ocean and Earth Science, University of Southampton, Southampton, United Kingdom
*corresponding author

keywords: Sea level variability and trend, Thermosteric and halosteric effect, Atmospheric contribution, Eastern Mediterranean

Received 21 April 2021, Revised 14 September 2021, Accepted 15 September 2021, Available online 1 October 2021, Version of Record 11 February 2022.

Abstract

Sea level trends and their forcing over the eastern Mediterranean basin are investigated by using 27 years (1993–2019) of gridded sea level anomalies (SLA) derived from satellite altimetry and 9 tide gauge stations, along with sea surface temperature (SST) and temperature and salinity profiles. The contributions of atmospheric (wind and pressure) and steric components to the interannual variability of total SLA were evaluated. The thermosteric component represents the major contributor to the linear trend and was positive over most of the eastern Mediterranean, with a spatially averaged trend of 2.13±0.41 mm/year, accounting for 69% of the total sea level trend (3.1±0.61 mm/year). In contrast, the halosteric effect has a negative contribution to the steric SLA, with a mean trend of -0.75±0.19 mm/year. The atmospheric component trend was much lower at 0.32±0.24 mm/year. The interannual variability of SLA accounts for about 36% of overall sea level variability. Steric and atmospheric contributions to the interannual variability of sea level in the eastern Mediterranean account for about 52% and 18%, respectively. The strongest interannual variability and trends in SLA were observed over the basin's main recurrent gyres, with the maximum positive trend obtained over the Mersa–Matruh and Cyprus gyres, as well as the North Shikmona eddy, and maximum negative trend over the Ierapetra gyre. Over the study period, all tide gauges showed a positive and statistically significant trend, ranging from 1.47±0.77 to 5.79±1.32 mm/year after applying glacial isostatic adjustment and atmospheric correction, and were in good agreement with reconstructed steric sea level data.
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Inhibitory effects of the brown macroalga Turbinaria ornata on cyst germination and progeny cells of five harmful dinoflagellate species
Oceanologia 2022, 64(1), 63-74
https://doi.org/10.1016/j.oceano.2021.09.002

Zakaria Mohamed1,*, Saad Alamri2, Mohamed Hashem2,3
1Department of Botany, Faculty of Science, Sohag University, Sohag, Egypt;
e-mail: Zakaria.attia@science.sohag.edu.eg, mzakaria_99@yahoo.com
2Biological Science Department, Faculty of Science, King Khalid University, Abha, Saudi Arabia
3Botany and Microbiology Department, Faculty of Science, Assiut University, Assiut, Egypt
*corresponding author

keywords: Cysts, Dinoflagellates, Harmful blooms, Macroalgal allelopathy

Received 21 January 2021, Revised 24 July 2021, Accepted 16 September 2021, Available online 12 October 2021, Version of Record 11 February 2022.

Abstract

This study investigates the inhibitory effects of thalli and their extracts of the macroalga Turbinaria ornata on the germination of dinoflagellate cysts, previously isolated from Red Sea surface sediments. The experiments were conducted on cysts of five harmful dinoflagellate species including Alexandrium catenella, Cochlodinium polykrikos, Dinophysis accuminata, Prorocentrum cordatum and Scrippsiella trochoidea. The results showed neither macroalgal thalli nor their extracts had direct impact on the cyst germination of all species. Instead, these macroalgal materials remarkably affected the germling viability and culturability of progeny cells of these cysts. Dry macroalgal thalli exhibited stronger inhibitory effects on germling viability and cell culturability (IC50= 0.235–0.543, 0.385–1.43 mg mL−1, respectively) than fresh thalli (IC50=2.201–4.716, 2.17–7.18 mg mL−1, respectively). The macroalgal ethanol extract was approximately 2-5 times more effective (IC50 = 0.012–0.047 and 0.024–0.089 mg mL−1, respectively) than aqueous extract (IC50 = 0.04–0.1 and 0.054–0.207 mg mL−1, respectively) against the germling viability and vegetative progeny cells of all cyst species. Among different species, A. catenella and C. polykrikos germlings were more sensitive to macroalgal thalli and their extracts than those of S. trochoidea, P. cordatum and D. acuminata. Meanwhile, progeny cells of A. catenella exhibited the highest sensitivity to all macroalgal materials. Our results suggest that the use of T. ornata may be a promising strategy for inhibiting the division of progeny cells of dinoflagellate cysts and impairing the recurrence of HABs in confined coastal areas.
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Spatial variability of summer hydrography in the central Arabian Gulf
Oceanologia 2022, 64(1), 75-87
https://doi.org/10.1016/j.oceano.2021.09.003

Elnaiem Ali Elobaid*, Ebrahim M.A.S. Al-Ansari, Oguz Yigiterhan, Valliyil Mohammed Aboobacker, Ponnumony Vethamony
Environmental Science Center (ESC), Qatar University, Doha, Qatar;
e-mail: elnaiemali123@gmail.com, elnaiem@qu.edu.qa

keywords: Arabian Gulf, Exclusive Economic Zone (EEZ) of Qatar, Physicochemical parameters, Water masses, Stratification

Received 27 April 2021, Revised 15 September 2021, Accepted 16 September 2021, Available online 12 October 2021, Version of Record 11 February 2022.

Abstract

The Arabian Gulf is a very significant ocean body, which hosts more than 55% of the oil reserves of the world and produces about 30% of the total production, and thus, it is likely to face high risk and adverse problems by the intensified environmental stressors and severe climatic changes. Therefore, understanding the hydrography of the Gulf is very essential to identify various marine environmental issues and subsequently, developing marine protection and management plans. In this study, hydrography data collected at 11 stations along 3 linear transects in the early summer of 2016 were analyzed. The physicochemical parameters exhibited apparent variations along each transect, both laterally and vertically, connected to stratification, formation of different water masses and excessive heating. The temperature and salinity decreased laterally from nearshore to offshore, while layered density structures were identified in the offshore regions. The pH, dissolved oxygen (DO) and chlorophyll fluorescence (Fo) exhibited distinct horizontal and vertical variations. The observed pH is within the normal ranges, indicating that seawater acidification may not be a threat. The highest DO (6.13–8.37 mg/l) was observed in a layer of 24—36 m water depth in the deeper regions of the central transect.
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Assessment of Sentinel-2 to monitor highly dynamic small water bodies: The case of Louro lagoon (Galicia, NW Spain)
Oceanologia 2022, 64(1), 88-102
https://doi.org/10.1016/j.oceano.2021.09.004

Gema Casal*
National Centre for Geocomputation, Maynooth University, Maynooth, Co. Kildare, Ireland;
e-mail: gema.casal@mu.ie
* corresponding author

keywords: Coastal lagoons, Intermittent inlet, Water bodies, Coastal monitoring, Multiband water indices

Received 8 April 2021, Revised 15 September 2021, Accepted 17 September 2021, Available online 6 October 2021, Version of Record 11 February 2022.

Abstract

Coastal lagoons have been providing ecological, economic and cultural benefits for many centuries. Despite their importance, the monitoring of coastal lagoons poses numerous challenges related to their complex environmental processes, their large variability in size and their remote location, inhibiting effective management programmes. This study demonstrates the effectiveness of Sentinel-2 satellites to map highly dynamic morphological and hydrological changes in the Louro lagoon, a small choked lagoon located on the Galician coast (NW Spain). For this purpose, a simple methodology using the Normalised Difference Water Index (NDWI) has been evaluated, which allows to monitor the sand barrier changes and the inlet formation. The results show that the sand barrier's opening and closing might take only a very short period, and the recovery of the lagoon to its full water level can happen in less than a month. Sentinel-2 images also reveal drastic changes in the water level once the sand barrier is broken. A water surface area of 0.24 km2 was estimated on 04/11/2019, while this surface was reduced to 0.10 km2 on 04/12/2019. Monitoring these changes is critical to understand the different processes ongoing in these valuable environments and making informed decisions for their management and protection.
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Combining multivariate statistical analysis to shed light on distribution and interaction of halogens in two economic ports along Red Sea Coast in Egypt
Oceanologia 2022, 64(1), 103-116
https://doi.org/10.1016/j.oceano.2021.09.007

Gehan M. El Zokm*, Ghada F. El-Said*, Abeer A.M. El Sayed*
National Institute of Oceanography and Fisheries, NIOF, Egypt;
e-mail: ghadafarouk25@yahoo.com, ghadafarouk25@gmail.com
gehanelzokm@yahoo.com, perry201277@hotmail.com
*corresponding author

keywords: Halogens, Seawater, Sediment, Multivariate analysis, Mabahiss and Safaga bays, Red Sea

Received 14 February 2021, Revised 15 August 2021, Accepted 29 September 2021, Available online 14 October 2021, Version of Record 11 February 2022.

Abstract

Mabahiss Bay and Safaga Bay are two important ports along the Red Sea coast of Egypt. The present study is the first to monitor halogen concentrations in these two ports. Certain halogens (F, Cl, Br and I) in coastal waters and sediments exhibited different behaviors. Fluoride (1.92–8.31 mg/L and 0.34–1.24 mg/g), chloride (20.76–22.68 g/L and 0.38–8.31 mg/g), bromide (95.90–151.84 mg/l and 6.66–50.61 mg/g), and iodide (2.77–39.19 μg/L and 1.71–3.76 μg/g) appeared in the seawater and sediments of Mabahiss Bay, respectively. In Safaga Bay, F, Cl, Br and I yielded ranges of (1.80–10.15 mg/L and 0.14–0.74 mg/g), (21.47–22.57 g/L and 0.68–1.42 mg/g), (15.98–146.51 mg/L and 6.13–74.59 mg/g) in seawater and sediments, respectively. In Mabashis Bay exclusively, the bromide and iodide levels in seawater increased significantly, and the sediments were vice versa. The average fluoride value in the two ports' seawater was higher than that in the unpolluted Mediterranean Sea. In contrast, the average bromide content in Mabahiss Bay seawater exceeded the Mediterranean Sea level. The seawater chloride content of the two ports was within the Mediterranean seawater's value, but the iodide concentration was lower than that of the unpolluted seawater. The application of different multivariate statistical techniques showed that halogen's distribution and halogen's geochemical characteristics control interaction in each region, ground flux, and proximity to human sources.
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Chemical characterization and biochemical activity of polysaccharides isolated from Egyptian Ulva fasciata Delile
Oceanologia 2022, 64(1), 117-130
https://doi.org/10.1016/j.oceano.2021.09.008

Madelyn N. Moawad1, Abeer A.M. El-Sayed1, Hala H. Abd El Latif1, Naglaa A. El-Naggar1,2, Nihal G. Shams El-Din1, Hermine R.Z. Tadros1,*,
1National Institute of Oceanography and Fisheries, NIOF, Egypt;
e-mail: herminetadros@gmail.com 2Department of Chemistry, College of Science, University of Hafr Al Batin, Hafr Al Batin, Saudi Arabia
*corresponding author

keywords: Ulvan, Chemical composition, Biological activities, FT-IR, 1H NMR

Received 30 January 2021, Revised 28 September 2021, Accepted 30 September 2021, Available online 14 October 2021, Version of Record 11 February 2022.

Abstract

This study gives updated information on the isolation of ulvan from green alga Ulva fasciata Delile in Egypt through isolation and chemical characterization of sulfate polysaccharides by two sequential extraction steps using different solvents; distilled water, HCl and Na2EDTA forming fraction I (F-I). Fraction II (F-II) was obtained from remaining seaweeds using NaOH to give FDWNaOH, FHClNaOH, and FEDTANaOH. All products obtained were tested for their biological activities. The highest polysaccharides total extraction yield was 11.8% for water extract (F-I and F-II). The highest protein content was found in FEDTANaOH (2.44%). The highest sulfate content was recorded for F-I (HCl) (21.38%). Total carbohydrates range was 11.99–63.90% for F-I and 15.06–76.65% for F-II. Monosaccharides; galactose, rhamnose, and uronic acid were detected at all fractions, with concentrations varying from 0.11 to 1.34%, from 0.61 to 1.81% and from 11.06 to 19.30%, respectively. 1H NMR of F-II demonstrated the signals of ring and methyl protons of polysaccharide. The appearance of the stretching bands of the sulfate ester (C-O-S) and sulfate groups (S=O) in the FT-IR spectrum of FHClNaOH confirmed the presence of sulfated polysaccharides, typical of ulvan. The microbial species Vibrio damsela was the most susceptible to FDWNaOH, followed by Aeromonas hydrophila and Vibrio fluvialis with inhibition zones of 30, 22, 22 mm at 150 mg/ml, respectively. FDWNaOH was the most effective fraction having antifouling property. The highest antioxidant activity was observed for F-IHCl followed by FDWNaOH. At concentrations 25 and 50 mg/l, FEDTANaOH displayed the highest anti-inflammatory activity (94.0 and 91.40%, respectively).
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Response of the Bay of Bengal to super cyclone Amphan examined using synergistic satellite and in-situ observations
Oceanologia 2022, 64(1), 131-144
https://doi.org/10.1016/j.oceano.2021.09.006

Neethu Chacko*, Chiranjivi Jayaram
Regional Remote Sensing Centre – East National Remote Sensing Centre, ISRO, Kolkata, India;
e-mail: herminetadros@gmail.com
*corresponding author

keywords: Amphan, Tropical cyclone, Bay of Bengal, Sea Surface Temperature, Salinity, Upper ocean response, Mixed layer budget

Received 9 February 2021, Revised 27 September 2021, Accepted 30 September 2021, Available online 14 October 2021, Version of Record 11 February 2022.

Abstract

Tropical cyclone Amphan is the first super cyclone that happened in the north Indian Ocean in the last 20 years. In this work, multi-platform datasets were used to investigate the responses of the upper ocean to cyclone Amphan. The most striking response was the cold wake left by the cyclone spanning the entire Bay of Bengal with an amplitude up to ∼4°C. Satellite salinity observations revealed that the maximum increase in surface salinity was ∼1.5 PSU on the right side of the track of Amphan. Surface circulation was also observed to be modulated with the passage of a cyclone with a rightward bias in the change in its speed and direction. The currents observed from a moored buoy showed strong inertial oscillations. Argo observations showed that changes induced by the cyclone occurred up to 150 m depth of the cyclone and ocean heat content in the upper 150 m depth decreased due to the passage of the cyclone. There was an enhancement of surface chlorophyll concentration (∼1.5 mg/m3) after the passage of the cyclone, which was centred along the track of the cyclone where the winds were the highest. Mixed layer heat and salinity budget analysis showed that the sea surface cooling and increase in salinity was primarily driven by vertical mixing processes, though horizontal advection contributed meagrely. This study also brings forward the fact that regional differences exist in the responses of the ocean to the forcing of cyclones.
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Asterionellopsis glacialis (Family: Fragilariaceae, Class: Bacillariophyceae, Phylum: Ochrophyta) bloom and its impact on plankton dynamics at Kalpakkam (Bay of Bengal, Southeast coast of India)
Oceanologia 2022, 64(1), 145-159
https://doi.org/10.1016/j.oceano.2021.04.005

Gouri Sahu1, Ajit Kumar Mohanty1,*, Ranjit Kumar Sarangi2, Kamala Kanta Satpathy3
1Radiological and Environmental Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, India;
e-mail: ajit@igcar.gov.in
2Planetary Sciences & Marine Biology Division, Space Applications Centre (ISRO), Ahmedabad, India
3Department of Environmental Science, Central Univeristy of Rajasthan, India
*corresponding author

keywords: Asterionellopsis bloom, Phytoplankton, Zooplankton, Plankton dynamics, Coastal waters, Southeast coast of India

Received 24 September 2020, Revised 10 April 2021, Accepted 28 April 2021, Available online 21 May 2021, Version of Record 11 February 2022.

Abstract

An intense bloom of Asterionellopsis glacialis (Family: Flagilariaceae; Class: Bacillariophyceae; Phylum: Ochrophyta) was observed in the near-shore waters at Kalpakkam, Tamil Nadu. Proliferation was supported by the favorable temperature, salinity, and nutrient levels in the coastal waters prevailing in the post-northeast monsoon period. BIOENV analysis and PCA confirmed salinity and nitrate as the key environmental factors responsible for the A. glacialis abundance. Cluster analysis further supported the distinct state of coastal water during the bloom with respect to physicochemical properties. The bloom period was floristically and faunistically richer than the pre- and post-bloom periods. The cluster and nMDS analysis confirmed the effects of bloom on plankton dynamics in the near-shore waters at Kalpakkam. The dominance of meroplankters especially, Cirripedia nauplii and Bivalvia larvae over Copepoda during the peak bloom period, was a significant result of the study. PCA ordination plot for the quantitative aspects of phytoplankton and zooplankton groups further supported the above observation. Among Copepoda, Cyclopoida and Poecilostomatoida (mostly carnivorous) exceeded the Calanoida (mostly herbivorous) during the peak bloom period unlike the reverse trend observed during other periods. Fish eggs and larvae were available in substantial numbers during the bloom which indicated their proliferation in the presence of the blooming diatom standing stock as the food material.
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Defining a single set of calibration parameters and prestorm bathymetry in the modeling of volumetric changes on the southern Baltic Sea dune coast
Oceanologia 2022, 64(1), 160-175
https://doi.org/10.1016/j.oceano.2021.10.004

Natalia Bugajny*, Kazimierz Furmańczyk*
University of Szczecin, Institute of Marine and Environmental Sciences, Szczecin, Poland;
e-mail: natalia.bugajny@usz.edu.pl, kazimierz.furmanczyk@usz.edu.pl
*corresponding author

keywords: XBeach, Model calibration, Coastal erosion, Volume errors

Received 24 April 2021, Revised 26 September 2021, Accepted 15 October 2021, Available online 5 November 2021, Version of Record 11 February 2022.

Abstract

The studies described herein aimed to estimate the accuracy of determination of the volumetric changes on the dune coast of the southern Baltic Sea through the application of the XBeach numerical model, which is crucial for coastal engineering. In the first phase of the study, the profile (1D) mode of the model was adapted to 19 cross-shore profiles located along the Dziwnów Spit.
The model was calibrated with a storm event in 2009 that caused significant changes to dunes and beaches. Cross-shore profiles were measured approximately one and a half months before and after the storm. An evaluation of model performance was made based on the Brier skill score (BSS), the visual match of the profile shape (VMS), the absolute volumetric change error (m3/m) and the relative volumetric change error (%). In this study, parameters related to the asymmetry transport (facua) and the dune erosion algorithm (wetslp) were taken into account.

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Temporal variations of phytoplankton community and their correlation with environmental factors in the coastal waters of the Çanakkale Strait in 2018
Oceanologia 2022, 64(1), 176-197
https://doi.org/10.1016/j.oceano.2021.10.003

Egemen İnan Demir, Muhammet Turkoglu*
Faculty of Marine Sciences and Technology, Canakkale Onsekiz Mart University, Canakkale, Turkey;
e-mail: mturkoglu@comu.edu.tr
*corresponding author

keywords: Çanakkale Strait, Phytoplankton, Biodiversity, Chlorophyll a, Environmental parameters

Received 19 March 2021, Revised 30 September 2021, Accepted 15 October 2021, Available online 23 November 2021, Version of Record 11 February 2022.

Abstract

In order to investigate temporal variations in phytoplankton connected with hydrography, high-resolution (twice a week) samplings were carried out between January and December 2018 at a single, shallow water station in the Dardanelles. Diatoms dominated in early and mid-winter, late spring and early summer, and between August and October. Whereas dinoflagellates dominated in the period from mid-February to the end of the third week of May, mid-summer, and late autumn. Other groups were generally more abundant in the early summer and mid-autumn than any other period. Late spring and early summer, mid-autumn and middle winter were the important bloom periods. The average contribution of diatom abundance (5.00 × 105±7.80 × 105 cells L−1) to average total phytoplankton abundance (9.63 × 105±7.88 × 105 cells L−1) was above 50% (average: 51.88%) during the year except spring (34.32%). However, the average contribution of dinoflagellates (43.32±20.69%) and others (4.81±6.99%) to the total phytoplankton abundance were lower than the abundance of the diatoms (51.88±21.61%). The study revealed a decrease both in the total number of algal blooms which also included HABs and their densities in the region compared to the previous findings. These observations seem to evidence environmental status improvement of the investigated area, manifested in an average chlorophyll a concentration (0.71±0.52 µg L−1) and quantitative phytoplankton structure (103 to 105 cells L−1).
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On Baltic herring morphometry and its impact on the backscattering properties
Oceanologia 2022, 64(1), 198-211
https://doi.org/10.1016/j.oceano.2021.10.001

Natalia Gorska1,*, Jakub Idczak2
1Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland;
e-mail: gorska@iopan.pl 2Institute of Oceanography, Faculty of Oceanography and Geography, University of Gdańsk, Gdynia, Poland
*corresponding author

keywords: Backscattering, Target strength, Numerical modelling, Baltic herring

Received 26 April 2021, Revised 14 October 2021, Accepted 20 October 2021, Available online 12 November 2021, Version of Record 11 February 2022.

Abstract

Previous studies, dedicated to backscattering properties of Baltic herring, have shown the different target strength (TS – which is a measure of fish capacity to scatter sound) values, for the same species in different regions and seasons. The intraspecies differentiation in fish physiology and morphology as well as fish swimbladder morphometry between herring aggregations, occupying various parts of the Baltic Sea, has been supposed as one of the reasons for the variability.
The paper addresses analysis of herring swimbladder morphometry and its impact on TS of individuals from ICES subdivision 26, one of the areas where Poland is responsible for herring biomass estimation. The collection of the X-rays images for 74 herring individuals, sampled in this subdivision, was created. The two-dimensional digitized dorsal images of herring swimbladder and body, as well as the angles between the swimbladder and the body longitudinal axis, were used to compute the target strength. The differentiation of herring morphometry within particular fish size classes was analysed and its consequences for the averaged target strength within the class was discussed. The difference from the previous numerical studies, in which the simplified herring morphometry was used, was also demonstrated. The computational results were considered in regard to the available in situ measured data on Baltic herring TS. The study of the Baltic herring target strength is important for increasing accuracy of acoustic biomass estimation of this ecologically and economically important species.
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Bedforms evolution in the Vistula River mouth during extreme flood event, southern Baltic Sea
Oceanologia 2022, 64(1), 212-226
https://doi.org/10.1016/j.oceano.2021.10.005

Aliaksandr Lisimenka1,2,*, Adam Kubicki3, Maciej Kałas1
1Maritime Institute, Gdynia Maritime University, Gdańsk, Poland;
e-mail: alisimenka@im.umg.edu.pl, sasha@iopan.pl 2Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland
3GEO Ingenieurservice Nord-West, Wilhelmshaven, Germany
*corresponding author

keywords: Bedform geometry, Bed roughness, Flood event, Anti-clockwise hysteresis, Spectral analysis, Vistula River mouth

Received 6 August 2021, Revised 9 October 2021, Accepted 20 October 2021, Available online 6 November 2021, Version of Record 11 February 2022.

Abstract

Results of bathymetric surveys conducted to examine changes of sand dunes geometry in the Vistula River mouth before, during and after the extreme flood event are presented. A total of 2076 dunes were analysed based on a series of bed elevation profiles obtained along the centreline of about 3.3 km length. Low-steepness dunes characterized by the mean lee-side slopes milder than β<10° are fully dominant at low flows. In contrast, at high hydrology, nearly 50% of dunes indicate β>10°. Dune height and length are substantially out of phase with progressive changes of water discharge exposing a well-pronounced anti-clockwise hysteresis. Distinct behaviour of dune dimensions reflected in increasing of dune steepness H/λ of about 3-fold and decreasing of about 4-fold were observed during rising and falling discharges, respectively. The bed roughness due to dunes presence showed changes of about 10-fold during the both of limbs and is found to be in range of about kdunes=(1/5÷3/5)Hmean. At the mesoscale region, spectra followed sufficiently by the ‘–3 power law’ for low hydrology, with steeper spectrum slopes close to ‘–4’ during moderate and high water discharges. With the development of the flood, potential of flow separation phenomena was increased of about 9-fold, from 2.2% at the flood beginning phase up to 20% at the flood peak. The obtained results could be used for the improvement of the hydraulic numerical models in sand-bed rivers to predict bedforms evolution, flow resistance and turbulence as well as water levels for proper river system management during flood events.
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Short communication



A substantial range expansion of alien Ponto-Caspian amphipods along the eastern Baltic Sea coast
Oceanologia 2022, 64(1), 227-232
https://doi.org/10.1016/j.oceano.2021.09.005

Denis Copilaş-Ciocianu*, Eglė Šidagytė-Copilas
Laboratory of Evolutionary Ecology of Hydrobionts, Nature Research Centre, Vilnius, Lithuania;
e-mail: denis.copilas-ciocianu@gamtc.lt
*corresponding author

keywords: Estonia, First record, Invasive crustaceans, Latvia, Transitional waters

Received 24 May 2021, Revised 5 September 2021, Accepted 16 September 2021, Available online 8 October 2021, Version of Record 11 February 2022.

Abstract

We report a considerable range expansion of four Ponto-Caspian amphipod species in transitional waters along the southeastern Baltic Sea coast. Chaetogammarus warpachowskyi and Dikerogammarus haemobaphes were found for the first time in Latvia, the former being common along the coast, while the latter was encountered only in the port of Riga. This indicates a 400 to 600 km expansion along the coast, assuming an origin from the Curonian or Vistula lagoons. We also officially document an expansion for Chelicorophium curvispinum in Latvia of ca. 300 km until Riga, confirming recent unpublished records. Moreover, we document a second invasion route of Pontogammarus robustoides into Estonia from nearby Latvian waters by uncovering a population at the port of Pärnu. This species was previously known in Estonia only from the Gulf of Finland (>500 km from Pärnu). With the exception of D. haemobaphes, all newly recorded species were represented by various life-stages and ovigerous females, indicating viable populations. Overall, our findings reveal that Ponto-Caspian amphipods are much more widespread in the Baltic area than previously known and highlight the need for more stringent monitoring.
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