Oceanologia No. 63 (2) / 21


Original research article

Short communication

Original research article

The pathway of the water exchange over the Gdańsk-Gotland Sill of the Baltic Sea and its impact on habitat formation during the stagnation period
Oceanologia 2021, 63(2), 163-178

Alexander Krek1,*, Andrey Gusev1,2,*, Elena Krek1,*, Viktor Krechik1,*, Mariia Kapustina1,*, Aleksei Kondrashov1,*, Ivan Dudkov,1,*
1Shirshov Institute of Oceanology of Russian Academy of Sciences, Moscow, Russia;
e-mail: av_krek_ne@mail.ru , andgus@rambler.ru , elenka_krek@mail.ru , myemail.gav@gmail.com , kapustina.mariya@ya.ru , kondrashoff1984@yandex.ru , 55671232@mail.ru
2Atlantic branch of the Federal State Budget Scientific Institution “Russian Federal Research Institute of Fisheries and Oceanography”, Kaliningrad, Russia;
*corresponding author

keywords: Southern Baltic Sea, Gdańsk-Gotland Sill, Near-bottom water exchange, Habitats, Advection, Stagnaton period

Received 19 August 2020, Revised 16 November 2020, Accepted 18 November 2020, Available online 30 November 2020.


Water exchange between the deep basins of the Baltic Sea during stagnation periods ventilates the bottom layer. Such exchange may be local and associated with the seabed topography features. The aim of this study is to investigate the possible pathway of water exchange within the Gdańsk-Gotland Sill. A comprehensive study was conducted near the one of the local erosional trenches (depressions), comprising bathymetric survey using multibeam echosounder, water column CTD-sounding, tilt current meters mooring, and sampling of seabed deposits and macrozoobenthos. The absence of pelitic sediments even in the natural trench depressions was identified. The seabed is composed of dense clays with surface erosion signs. The presence of a current towards the Gotland Basin was recorded in the bottom layer of the erosional trench. This layer was characterized by increased salinity and dissolved oxygen concentration. The trench was also an area with macrozoobenthos richer in species composition and biomass. Moreover, indicator species of the North Sea waters were found exclusively within the erosional trench. Macrozoobenthic community structure and the age of benthic organisms confirm the existence of permanent water exchange directly from the Słupsk Furrow through the erosional trench, and indicate one of the advective pathways of water exchange between the deep Baltic Sea basins.
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Taphonomy of mass mollusc shell accumulation at Amvrakikos Gulf lagoon complex sandy barriers (NW Greece)
Oceanologia 2021, 63(2), 179-193

Konstantinos Tsolakos*, George Katselis, John A. Theodorou
Department of Animal Production, Fisheries and Aquaculture, School of Agricultural Sciences, Patras University, Mesolonghi, Greece;
e-mail: k.tsolakos@upatras.gr
*corresponding author

keywords: Taphonomic analysis, Amvrakikos Gulf, Bivalves shells accumulation, Lagoon sandy barriers, Cerastoderma glaucum, Polititapes aureus

Received 12 August 2020, Revised 27 November 2020, Accepted 30 November 2020, Available online 11 December 2020.


The preservation status of the mollusc shell accumulation of sandy barriers at the Amvrakikos Gulf lagoon complex was studied. Taphonomic shell analysis of dead mollusc depositions was undertaken in the summer of 2016 at Amvrakikos lagoon complex within the Tsoukalio and Logarou sandy barriers, which showed significant differences among the major abundant bivalve species of Cerastoderma glaucum and Polititapes aureus. Both hydrodynamic transport and differential exposure to environmental conditions differ among the accumulated shells depositions of the lagoonal sandy barriers. The heavier and more durable shells of C. glaucum are frequently found concentrated at the Tsoukalio lagoon accumulations and show a higher intensity of fragmentation whereas at Logarou lagoon the bioerosion and abrasion is more intense. On the other hand, the lighter, thinner, and thus more fragile shells of P. aureus show higher concentration and intensity of fragmentation and bioerosion at Logarou lagoon sandy barriers.
The continuous deposition of shells at Tsoukalio lagoonal sandy barriers, contrary to the long-term deposition at Logarou lagoon, explains the different types of accumulations among the lagoons which are attributed to the geomorphology of the sandy shores as well as the morphological characteristics of the different shells.

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WAVEWATCH-III source terms evaluation for optimizing hurricane wave modeling: A case study of Hurricane Ivan
Oceanologia 2021, 63(2), 194-213

Mehdi Yaghoobi Kalourazi1, Seyed Mostafa Siadatmousavi1,*, Abbas Yeganeh-Bakhtiary1, Felix Jose2
1School of Civil Engineering, Iran University of Science and Technology, Narmak, Tehran, Iran;
e-mail: siadatmousavi@iust.ac.ir
2Department of Marine & Earth Sciences, Florida Gulf Coast University, Fort Myers, FL, USA
*corresponding author

keywords: Third generation wave model, Hurricane Ivan, Whitecapping dissipation, Swell dissipation, Gulf of Mexico

Received 19 August 2020, Revised 10 December 2020, Accepted 14 December 2020, Available online 26 December 2020.


Simulating hurricane-generated waves is a challenging task due to rapidly fluctuating wind speed and direction, simultaneous presence of swells propagating out of the previous location of the hurricane and following/opposing waves on either side of the hurricane track, and dissipation in wind speed radially from the center of the hurricane. Bulk wave parameters have been investigated using the source term packages ST3, ST4 and ST6 implemented in the WAVEWATCH-III model to determine the most appropriate formulation for simulating hurricane-generated waves in the Gulf of Mexico. Based on the comparisons between model results and in situ observations during the passage of Hurricane Ivan (2004), it is shown that ST3 is not as successful as other formulations for hurricane wave modeling. Calibrated ST6 variant, T12, has shown to be the best formulation for simulating bulk wave parameters at points within the range of hurricane wind forcing; however, for the area beyond, and also during fair weather conditions, calibrated ST4 formulation, T471-Ex4, is recommended. Although T471-EX4 and T12 packages outperformed other cases, they overestimated waves propagating in the oblique and opposing wind. Dependence of ST6 parameter.
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Development of the sandy coast: Hydrodynamic and morphodynamic conditions (on the example of the Eastern Gulf of Finland)
Oceanologia 2021, 63(2), 214-226

Boris V. Divinsky1,*, Darya V. Ryabchuk2, Ruben D. Kosyan1, A. Yu. Sergeev2
1Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia;
e-mail: divin@ocean.ru
2Russian Geological Research Institute (VSEGEI), St. Petersburg, Russia
*corresponding author

keywords: Wind seas, Swell, Baltic Sea, Numerical modeling, Longshore sediments transport, Coastal evolution

Received 29 September 2020, Revised 2 December 2020, Accepted 21 December 2020, Available online 6 January 2021.


Forecasting the coastal zone development under possible climatic changes and technogenic impact is an extremely important task. This forecasting is based on our understanding of the mechanism of the hydrodynamic processes impact on the coastal zone. The goal of this work is to describe the hydrodynamic conditions (currents, sea level, surface waves) of coastal waters and to assess the influence of hydrodynamic parameters on the general dynamics of the beach. The object of this study is a part of the southern coastal zone of the Gulf of Finland (Baltic Sea). The method of research is a full-scale experiment and mathematical modeling. The initial data for the analysis are climatic characteristics of the hydrodynamic regime of the sea (velocity and direction of currents, sea level, integral parameters of wind seas and swell), as well as interannual variations in the position of the coastline in the region of the Izhora village in the eastern part of the Gulf of Finland. Interannual variations in hydrodynamic parameters and volumes of bottom material transported under the influence of wind seas and swell were estimated. Main conclusion: swell waves determine the general background in the patterns of the bottom material transport, and the contribution of wind seas is in the formation of beach properties, namely, the accumulation or decrease of beach material.
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Observed variability in physical and biogeochemical parameters in the central Arabian Gulf
Oceanologia 2021, 63(2), 227-237

Fazle Rakib1, Ebrahim M.A.S. Al-Ansari2,*, Yusuf Sinan Husrevoglu2,4, Oguz Yigiterhan2, Ibrahim Al-Maslamani3, Valliyil Mohammed Aboobacker2, Ponnumony Vethamony2
1Department of Biological and Environmental Sciences, Qatar University, Doha, P.O. Box: 2713, State of Qatar
2Environmental Science Center, Qatar University, Doha, P.O. Box: 2713, State of Qatar;
e-mail: isalansari@qu.edu.qa
3Office of Vice President for Research and Graduate Studies, Qatar University, P.O. Box: 2713, State of Qatar
4Institute of Marine Sciences, Middle East Technical University, 33731, Erdemli, Mersin, Turkey
*corresponding author

keywords: Hydrography, Dissolved oxygen, Chlorophyll-a, Ocean stratification, Seasonal hypoxia

Received 6 November 2020, Revised 26 December 2020, Accepted 30 December 2020, Available online 14 January 2021.


In situ measurements of physical and biogeochemical variables were conducted along a transect in the Exclusive Economic Zone (EEZ) of Qatar during late summer (September 2014) and winter (January 2015) to investigate their vertical, spatial and temporal variability. The study reveals that the water column is characterized by strong stratification during late summer in the deepest station, where the water depth is around 65 m and the surface to bottom temperature variation is around 9.1°C. The water column is vertically homogeneous during winter due to surface cooling and wind mixing. The surface to 23 m water column is characterized by ample dissolved oxygen (DO) during late summer and winter in the offshore regions, however, relatively low DO is found during late summer due to weak mixing and advection under weak winds and currents. Dissolved oxygen drops to hypoxic levels below the summer thermocline, and the winter high DO layer extends up to the bottom. Chlorophyll-a (Chl-a) is relatively high during late summer in the offshore region, while that in the nearshore regions is very low, which is linked to the anthropogenic stresses from the central east coast of Qatar. The results identified in this study fill an essential gap in the knowledge of regional primary production dynamics.
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Lidar observation of aerosol transformation in the atmospheric boundary layer above the Baltic Sea
Oceanologia 2021, 63(2), 238-246

Przemysław Makuch1,*, Stefan Sitarek2, Piotr Markuszewski1,3,4, Tomasz Petelski1, Tadeusz Stacewicz5
1Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland;
e-mail: makuch@iopan.pl
2Institute of Applied Optics, Warsaw, Poland
3Department of Environmental Science, Stockholm University, Stockholm, Sweden
4Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
5Institute of Experimental Physics, University of Warsaw, Warsaw, Poland
*corresponding author

keywords: Aerosol, Lidars measurements, Atmospheric boundary layer

Received 22 April 2020, Revised 28 January 2021, Accepted 29 January 2021, Available online 9 February 2021.


Investigation results of a coarse and accumulation mode of aerosol properties above the Baltic Sea are reported. A most important role in the direct aerosol effect on climate have aerosols from the group of coarse and accumulation mode particles. Overseas in the atmosphere, there is a lot of aerosols from the fine fraction but their impact is not so important as coarse and accumulation mode particles. Sea spray emission from the sea surface takes place over a wide range of aerosol particle size distribution, it is also large in size range which are studying in this work (Lewis and Schwartz, 2004). The discussed range is most important in view of atmospheric optical properties, smaller particles do not have such an influence on scattering as particles from range 0.5–2 µm. The research was performed with a multiwavelength lidar. Due to the application of special software, the aerosol particle size distributions were retrieved from the lidar returns. That provided an opportunity to determine the profiles of the aerosol effective radius. We showed that the aerosol properties depend mainly on the direction of the air mass advection and the wind speed. The impact of the Baltic Sea on the aerosol size distribution is huge in the case of the advection from the open sea. Moreover, the aerosol effective radiuses in the whole boundary layer are much larger in the case of strong than for light wind. Our results suggest that the aerosol flux and the aerosol particle size distribution should be related to the wind speed in the emission function.
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Microphytobenthic primary production on exposed coastal sandy sediments of the Southern Baltic Sea using ex situ sediment cores and oxygen optodes
Oceanologia 2021, 63(2), 247-260

Kana Kuriyama1, Sigrid Gründling-Pfaff1, Nora Diehl2, Jana Woelfel1, Ulf Karsten1,*
1Institute of Biological Sciences, Applied Ecology and Phycology, University of Rostock, Germany;
e-mail: ulf.karsten@uni-rostock.de
2Institute of Biology and Chemistry, Marine Botany, University of Bremen, Germany
*corresponding author

keywords: Benthic diatoms, C/N ratio, Respiration, Hydrodynamics

Received 26 August 2020, Revised 2 February 2021, Accepted 5 February 2021, Available online 18 February 2021.


The shallow coastal water zone of the tide-less southern Baltic Sea is dominated by exposed sandy sediments which are typically inhabited by microphytobenthic communities, but their primary production is poorly studied, and hence four stations between 3.0 and 6.2 m depth were investigated. Sediment cores were carefully taken to keep the natural layering and exposed in a controlled self-constructed incubator. Respiratory oxygen consumption and photosynthetic oxygen production were recorded applying planar oxygen optode sensors. We hypothesized that with increasing water depths the effects of wind- and wave-induced erosion and mixing of the upper sediment layer are dampened and expected higher microphytobenthic biomass and primary production in the incubated cores.

Our data partly confirm this hypothesis, as cores sampled at the most exposed stations contained only 50% chlorophyll a m−2 compared to the deeper stations. However, primary production was highly variable, probably due to fluctuating sediment-disturbing conditions before the cores were taken. Due to these physical forces sand grains were highly mobile and rounded, and small epipsamic benthic diatoms dominated, which preferentially occurred in some cracks and crevices as visualized by scanning electron microscopy. The data fill an important gap in reliable production data for sandy sediments of the southern Baltic Sea, and point to the ecological importance and relevant contribution of microphytobenthic communities to the total primary production of this marine ecosystem. Oxygen planar optode sensor spots proved to be a reliable, sensitive and fast detection system for ex situ oxygen exchange measurements in the overlying water of intact sediment cores.

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Response of coastal phytoplankton to upwelling induced hydrological changes in the Alappuzha mud bank region, southwest coast of India
Oceanologia 2021, 63(2), 261-275

Nikathithara Velappan Madhu*, Peariya Anil, Paul Meenu, Thundiyil Raju Gireeshkumar, Kallungal Ravunnikutty Muraleedharan, Thekkendavida Velloth Rehitha, Mathew Dayana, Chazhikulam Rajan Vishal
CSIR – National Institute of Oceanography, Regional Centre, Kochi, India;
e-mail: nmadhu@nio.org
*corresponding author

keywords: Mudbank, Upwelling, Phytoplankton, Chlorophyll a, Algal bloom, Alappuzha

Received 6 December 2020, Revised 2 February 2021, Accepted 5 February 2021, Available online 17 February 2021.


The response of phytoplankton community to the co-existing events of coastal upwelling and mud banks in the nearshore waters of Alappuzha (15 m depth), located in the southwest coast of India from April to November 2016, is described based on size-fractionated phytoplankton biomass (chlorophyll a), primary production and community composition. The study region exhibited well-distinct spatio-temporal hydrological changes because of the influence of wind-driven coastal upwelling, prevalent during the southwest monsoon (SWM) period. However, the formation of mud banks, in addition to coastal upwelling, was observed at station M2, which facilitated the substantial increase of water column turbidity and inorganic nutrients (ammonium, phosphate, and silicate) during and after the peak SWM period compared to the non-mud bank reference stations (M1 and M3). The prevailing hydrological changes were complemented the corresponding phytoplankton productivity patterns, in which profound domination of nanophytoplankton (2–20 µm) chlorophyll a and primary production was observed throughout the study region, irrespective of seasons. The SIMPER analysis, based on phytoplankton (mostly >20 µm) species composition data (microscopy), revealed the formation of certain characterizing species, mainly comprised of diatoms and dinoflagellates. The consistent predominance of the nanophytoplankton, established under variable hydrological scenarios, showed that the inorganic nutrient (specifically ammonium) availability was instrumental in defining the widespread growth of nanophytoplankton community compared to the prevailing light levels. The present study thus revealed that even the small-sized phytoplankton community could survive in the nutrient-enriched coastal waters, characterised by the co-existing upwelling and mud banks.
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Short communication

A system for the determination of surface water pCO2 in a highly variable environment, exemplified in the southern Baltic Sea
Oceanologia 2021, 63(2), 276-282

Marcin Stokowski*, Przemysław Makuch, Krzysztof Rutkowski, Marcin Wichorowski, Karol Kuliński
Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland;
e-mail: stokowski@iopan.gda.pl
*corresponding author

keywords: CO2 system, pCO2 measurements, Ship-to-shore data transmission

Received 30 October 2020, Revised 11 January 2021, Accepted 23 January 2021, Available online 4 February 2021.


Measurement of pCO2 in highly dynamic coastal zones such as the southern Baltic Sea presents many challenges. In this study, we designed a system to measure pCO2 and then validated it in a series of laboratory and seagoing tests. The fast response time of the system was shown to provide a better resolution of CO2 system gradients. In the open waters of the Baltic Sea, the accuracy of the pCO2 measurements (±1.3 µatm) met the requirements of the ICOS (±2.0 µatm). In the coastal zone, there was less consistency between pCO2, DIC and pH measurements, suggesting the need to redefine the quality assurance and control requirements for the measurement of pCO2 in dynamic regions.
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