Oceanologia No. 65 (1) / 23

Contents

Editorial foreword

Original research article

Original research article


Earth system changes in marginal seas
Oceanologia 2023, 65(1), v-viii
https://doi.org/10.1016/j.oceano.2023.01.001

Marcus Reckermann*, Jan Harff*, H.E. Markus Meier*, Karol Kuliński*, Hans von Storch*
e-mail: marcus.reckermann@hereon.de, e-mail: jan.harff@io-warnemuende.de, e-mail: markus.meier@io-warnemuende.de, e-mail: kroll@iopan.pl, e-mail: hvonstorch@web.de
*guest editor

Available online 6 January 2023, Version of Record 3 March 2023.
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Hazards evaluation of a valuable vulnerable sand-wave field forage fish habitat in the marginal Central Salish Sea using a submersible
Oceanologia 2023, 65(1), 1-19
https://doi.org/10.1016/j.oceano.2021.06.002

H. Gary Greene1,2,4,*, Matthew R. Baker2,3, John Aschoff4, Robert Pacunski5
1Center for Habitat Studies, Moss Landing Marine Labs, Moss Landing, CA, USA;
e-mail: greene@mlml.calstate.edu
2Friday Harbor Labs, University of Washington, Friday Harbor, WA, USA
3North Pacific Research Board, Anchorage, Alaska, USA
4Tombolo Mapping Lab, SeaDoc Society, Orcas Island, WA, USA
5Washington Department of Fish & Wildlife, Mill Creek, WA, USA
*corresponding author

keywords: Seafloor mapping, Marginal sea, Inland sea, Sedimentary bedforms, Forge fish

Received 6 February 2021, Revised 15 June 2021, Accepted 30 June 2021, Available online 14 July 2021, Version of Record 3 March 2023.

Abstract

The Salish Sea is a marginal inland sea of the NE Pacific (NW North America) that includes the Georgia Strait-Gulf Islands Archipelago of British Columbia, Canada and the San Juan Archipelago, Strait of Juan de Fuca, and the Lower Puget Sound of Washington State, USA. This marginal seafloor has been extensively mapped and according to criteria presented and discussed at GeoHab conferences critical marine benthic habitat types are identified. One such habitat that is the focus of this paper is the deep-water sub-tidal habitat of Pacific sand lance (PSL). The PSL (Ammodytes personatus) is a critical forage fish for a variety of mammals, birds and fish including minke whales and salmon as it preys upon zooplankton and acts as an energy transfer species from the lower to higher trophic levels. Pacific sand lance seeks refuge and overwinters in sand-wave fields consisting of dynamic bedforms. The species prefers loosely packed, well-aerated, well-sorted, medium- to coarse-grain (∼1 phi [φ], 500 µm) sand that it can burrow into easily. Such geomorphic features as active dynamic bedforms provide preferable habitats for PSL and depends on specific and unique oceanographic processes that can maintain the habitat's morphology and grain sizes. Understanding these processes is essential in forecasting alteration or destruction of such features, including changes that may be brought about by sea level rise. Using the five-person submersible Cyclops 1, we recently examined a well-studied sand-wave field in the San Juan Archipelago of Washington State, USA, which has been reported to harbor up to 12 million PSL. Observations, video recordings, and photography from this vehicle allowed us to assess modern seafloor processes of the central Salish Sea that can be used along with fish and sediment sample data to determine physical preferences this fish needs to sustain its population. Changes in the seafloor current regime, sediment source, and anthropogenic disturbances can critically alter these dynamic bedforms. This research provides insight into the structure of these bedforms, their composition, their persistence, their resilience to disturbance, and the susceptibility as an impact and becoming impacted.
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How to develop an understanding of the marginal sea system by connecting natural and human sciences
Oceanologia 2023, 65(1), 20-29
https://doi.org/10.1016/j.oceano.2021.06.003

Anders Omstedt
Department of Marine Sciences, University of Gothenburg, Sweden;
e-mail: anders.omstedt@marine.gu.se

keywords: Ocean, Marginal seas, Transdisciplinary, Art–science, UN SDGs

Received 18 February 2021, Revised 15 June 2021, Accepted 30 June 2021, Available online 14 July 2021, Version of Record 3 March 2023.

Abstract

The marginal seas are in the transition zone between land and ocean and are often subject to extensive human activities causing multiple stresses on the marine environment and its ecosystems. A large gap between our scientific knowledge and our treatment of the sea illustrates a weak coupling between facts and values. The aim of this work is to initiate a discussion of how to improve the human relationship with the sea. Research into the UN 2030 Agenda with its ambition to transform our world into a sustainable and healthy physical and mental environment creates an opportunity to deepen our understanding of human behaviour and values and how they impinge on the physical world. Together with improved communication and transdisciplinary initiatives, these efforts should be vital in better understanding the marginal sea system and generating a new relationship with the ocean.
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Natural and synthetic estrogenic compounds in the Pearl River Estuary and northern shelf of the South China Sea
Oceanologia 2023, 65(1), 30-43
https://doi.org/10.1016/j.oceano.2021.08.001

Carina Deich1,*, Marion Kanwischer1, Ruifeng Zhang2, Joanna J. Waniek1
1Leibniz Institute for Baltic Sea Research Warnemünde, Rostock, Germany;
e-mail: carina.deich@io-warnemuende.de
2School of Oceanography, Shanghai Jiao Tong University, Shanghai, China
*corresponding author

keywords: Estrogenic compounds, Estrogenic activity, Pearl River Estuary, South China Sea

Received 29 January 2021, Revised 30 June 2021, Accepted 12 August 2021, Available online 26 August 2021, Version of Record 3 March 2023.

Abstract

Endocrine disrupting compounds and in particular estrogenic substances have the ability to interact with the hormone system of organisms. Among them are not only synthetic but also natural substances that potentially stress the aquatic ecosystem. High human population densities such as around the Pearl River Estuary (PRE) are suspected of exerting significant anthropogenic pressure onto coastal areas. In this study, natural and synthetic estrogens as well as estrogen-like substances derived from plants and fungi were investigated in the PRE and at the adjacent northern shelf of the South China Sea. Maximum concentration of 3.6 ng L−1 for estrone (E1), 0.7 ng L−1 for 17α-ethinylestradiol (EE2), 12.9 ng L−1 for genistein (GEN), 11.9 ng L−1 for daidzein (DAI) and 1.9 ng L−1 for zearalenone (ZEN) were observed. While E1 and EE2 were detected in fresh and saltwater samples, GEN, DAI and ZEN were observed only at freshwater sampling sites. During the investigations, the analysis of 17β-estradiol (E2) and EE2 indicated a strong matrix dependence. Additionally, an estrogen screen observation showed estrogenic activity in form of estradiol equivalent quotients up to 0.18 ng L−1.
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Perceptions of an endangered Baltic Sea
Oceanologia 2023, 65(1), 44-49
https://doi.org/10.1016/j.oceano.2021.08.005

Hans von Storch1,2
1College of Oceanic and Atmospheric Sciences, Ocean University of China, Qingdao, China
2Institute of Coastal Research, Helmholtz-Zentrum Geesthacht, Geesthacht, Germany;
e-mail: hvonstorch@web.de

keywords: Baltic Sea, Environmental stressors, Climate change, Perceptions, Survey

Received 5 April 2021, Revised 9 July 2021, Accepted 25 August 2021, Available online 10 September 2021, Version of Record 3 March 2023.

Abstract

In a series of ad-hoc surveys at different academic institutions in the Baltic Sea region, students and young scholars were asked about their views about the environmental issues of the Baltic Sea, and who would be responsible for the management of the Baltic Sea. Overfishing, climate change and waste were considered the most significant issues, while tourism and constructions (of bridges, etc.) were less often recognized as severe. The responsibility for the management of the Baltic Sea was mostly attributed to the European Union or to the respective national governments.

Since climate is one of these issues, one question has dealt with the main task of climate science. It turns out that the most frequent assertion was not the genuine scientific task of generating knowledge about the dynamics of the system. Instead, the task of solving the problem and, equally often, supporting climate activism was favored.

The results are not representative – neither for the separate surveys, nor for the selection of the sites of surveying. However, when taken all surveys together, the emergence of consistent perceptions may be considered evidence for a general attitude among students and young scholars in the Baltic regions. However, differences between groups – in terms of nationality, seniority and discipline - may be related to sampling randomness.

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The significance of sea-level change and ancient submerged landscapes in human dispersal and development: A geoarchaeological perspective
Oceanologia 2023, 65(1), 50-70
https://doi.org/10.1016/j.oceano.2021.10.002

Geoff Bailey1,2,*, Hayley C. Cawthra3,4
1Department of Archaeology, University of York, King's Manor, Exhibition Square, York, United Kingdom;
e-mail: geoff.bailey@york.ac.uk
2College of Humanities, Arts and Social Sciences, Flinders University, Adelaide, Australia
3Geophysics and Remote Sensing Unit, Council for Geoscience, Western Cape Regional Office, Bellville, Cape Town, South Africa
4African Centre for Coastal Palaeoscience, Nelson Mandela University, Gqeberha, Eastern Cape, South Africa
*corresponding author

keywords: Continental shelf, Last Glacial Maximum, Postglacial marine, transgression, Integrated palaeoscience, Seabed mapping, Underwater archaeology, Underwater palaeoenvironments

Received 3 July 2021, Revised 1 October 2021, Accepted 21 October 2021, Available online 22 November 2021, Version of Record 3 March 2023.

Abstract

In this paper we highlight the impact of sea-level change on the archaeological record of key developments in human history that took place during the late Pleistocene and the early Holocene. Before modern sea level became established from ∼7 ka onwards, most palaeoshorelines and large areas of coastal hinterland were exposed as habitable land and then drowned again by sea-level rise. We summarise the archaeological implications of this pattern and the conditions in which archaeological and geoarchaeological evidence from these submerged landscapes is preserved despite the potentially destructive erosional impact of sea-level rise. We provide examples of palaeolandscape reconstruction made possible through multi-disciplinary collaboration between archaeology and marine science, drawing on recent underwater research in the North Sea, the Red Sea and on the Cape Coast of South Africa, and discuss evidence of past human responses to sea-level change. We identify the types of modelling procedures that need to be developed to advance this field of research, emphasise the importance of inter-disciplinary collaboration involving two-way exchange of ideas and information between archaeology and marine science, and highlight the value of a long-term perspective in understanding the present and future human impact of sea-level rise.
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Nearshore sandbar switching episodes and their relationship with coastal erosion at the Curonian Spit, Baltic Sea
Oceanologia 2023, 65(1), 71-85
https://doi.org/10.1016/j.oceano.2021.11.004

Rasa Janušaitė1,*, Darius Jarmalavičius1, Donatas Pupienis1, Gintautas Žilinskas1, Laurynas Jukna2
1Laboratory of Geoenvironmental Research, Nature Research Centre, Vilnius, Lithuania;
e-mail: rasa.janusaite@gamtc.lt
2Institute of Geosciences, Vilnius University, Vilnius, Lithuania
* corresponding author

keywords: Nearshore morphodynamics, Multiple sandbar system, Storms, Sand volume, Lithuania

Received 30 August 2021, Revised 5 November 2021, Accepted 22 November 2021, Available online 5 December 2021, Version of Record 3 March 2023.

Abstract

The longshore realignment of nearshore sandbars is a morphodynamic phenomenon of multiple sandbar systems that has been known about for several decades. However, it is unknown how switching-related nearshore changes influence the evolution of subaerial beaches. This study aims to define the relationship between sandbar switching episodes and the dynamic state of the beach-foredune system along the Curonian Spit coast (Baltic Sea) using decadal satellite-derived and beach profiling data. To define this connection, sandbar switching locations, sandbar cross-shore positions, shoreline positions, and sand volume changes in the beach-foredune system were assessed on interannual and storm-related time scales. Twenty-seven sandbar switching episodes were observed with an average duration of 14.3 months. Most of the switching episodes occurred at preferred locations, coinciding with breaking points of different shoreline orientations where oblique waves and longshore currents prevailed. Shoreline retreat at an average rate of –14.2 m was observed within most of the sandbar switching zones. During major storm events, the average rate of erosion within the sandbar switching zones was significantly higher than the rate outside them. On an interannual time scale, a moderate average rate of erosion was observed within the sandbar switching zones compared to a small accretion rate outside them. Additional case studies of coastal evolution within the switching zones indicated well-correlated rates of switching-determined outer sandbar positions, shoreline positions, and sand volume on the beach and foredune during the switching episodes. The results of this study could be important for the identification of erosional hot spots and coastal prediction.
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Model estimates of microplastic potential contamination pattern of the eastern Gulf of Finland in 2018
Oceanologia 2023, 65(1), 86-99
https://doi.org/10.1016/j.oceano.2021.11.006

Stanislav D. Martyanov*, Alexey V. Isaev, Vladimir A. Ryabchenko
Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia;
e-mail: martyanov.sd@gmail.com
*corresponding author

keywords: Microplastic, Modeling, Baltic Sea, Gulf of Finland

Received 27 April 2021, Revised 15 November 2021, Accepted 25 November 2021, Available online 10 December 2021, Version of Record 3 March 2023.

Abstract

The work is focused on the assessment of microplastics transport and distribution in the eastern part of the Gulf of Finland by means of numerical modeling. In the present study only the riverine sources of microplastics are taken into account. The presented model also accounts for possible sink of suspended microplastic particles into sediments due to simple parameterization of biogeochemical processes such as biofouling and ingestion by zooplankton. Two basic scenarios with different initial fall velocities of suspended microplastic particles, 0.2 m/day and 1.2 m/day, are discussed. The distribution of microplastics coming with the riverine waters of the Neva, Luga, and Narva rivers has been investigated, based on a numerical hydrodynamical hindcast of the year 2018. Model simulations show that the transport of suspended microplastics occurs along the northern coast of the considered area more intensively compared to the southern coast, especially in the easternmost shallow part of the gulf. The results are in a good agreement with other studies focused on the microplastic pollution of the Neva Bay, and with available observational data. The presented results and developed model can be useful tools aimed to assess the intensity and mechanisms of microplastic pollution of the eastern Gulf of Finland. The results can be used in the selection of areas for future environmental monitoring of microplastics pollution of the eastern part of the Gulf of Finland.
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Intermediate plumes of low oxygen in the southeastern Baltic Sea
Oceanologia 2023, 65(1), 100-116
https://doi.org/10.1016/j.oceano.2021.12.003

Maria Golenko*, Vadim Paka, Victor Zhurbas, Andrey Korzh, Alexey Kondrashov
Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia;
e-mail: m.golenko@yahoo.com, vpaka@mail.ru, victor.zhurbas@mail.ru, ao.korzh@yandex.ru, kondrashoff1984@yandex.ru
*corresponding author

keywords: Baltic Sea, Closely spaced CTDO profiling, Saltwater inflows, Hypoxic intermediate layers, Modelling, Lagrangian particles of neutral buoyancy

Received 4 August 2021, Revised 4 November 2021, Accepted 7 December 2021, Available online 26 December 2021, Version of Record 3 March 2023.

Abstract

Closely spaced CTDO profiling on the pathway of saltwater flow in the southeastern Baltic Sea in August and December 2019 revealed low oxygen intermediate layers-plumes with dissolved oxygen concentration (DOC) less than 2 mg/l under the upper boundary of permanent halocline. At the same time, DOC in the underlying layers was higher and reached 5.0–5.3 mg/l. In order to test the hypotheses about the origin of the intermediate hypoxic plumes, numerical hydrodynamic modelling was performed for time intervals including the measurement periods. The model was validated against bottom current velocity instrumental measurements by a TCM (Tilt Current Meter) moored on the track of the CTDO profiling. Numerical experiments with Lagrangian particles of neutral buoyancy coupled with the operational circulation model showed that sub-halocline hypoxic intermediate layers in the southern part of the Eastern Gotland Basin and in the Gdańsk Basin could be formed as a result of intrusion into the underlying bottom layer of denser, moderately oxygenated water from the Słupsk Furrow, which replaced the old anoxic and hypoxic water of Gotland and Gdańsk origin. It is assumed that cyclonic eddy activity above the saltwater flow along sloping bottom caused fragmentation of the hypoxic intermediate layer into separate plumes. The hypoxic intermediate layers in the Słupsk Furrow, in accordance with the results of monitoring measurements and modelling the motion of particles of neutral buoyancy, could be formed in the Bornholm Basin and moved eastward over the Słupsk Sill.
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Numerical simulations of wave climate in the Baltic Sea: a review
Oceanologia 2023, 65(1), 117-140
https://doi.org/10.1016/j.oceano.2022.01.004

Tarmo Soomere1,2
1Department of Cybernetics, School of Science, Tallinn University of Technology, Estonia;
2Estonian Academy of Sciences, Tallinn, Estonia
e-mail: soomere@cs.ioc.ee

keywords: Wave modelling, WAM, SWAN, Extreme waves, Climate change

Received 31 July 2021, Revised 10 January 2022, Accepted 17 January 2022, Available online 1 February 2022, Version of Record 3 March 2023.

Abstract

Efforts towards the numerical simulation of the Baltic Sea wave properties, started in the 1950s, have reached maturity by the implementation of contemporary third generation spectral wave models, such as WAM and SWAN. The purpose of this paper is to give an overview of the relevant efforts since the beginning of numerical wave simulations. The Sverdrup-Munk-Bretschneider (SMB) type models are still valuable tools for rapid estimates of some properties of wave climate in single locations. The spatial resolution of spectral wave models for the entire sea has increased from about 20 km to 1 km, and to 100–200 m in specific areas. The number of directional bins has increased from 10–15 to 24–36 and the number of spectral frequency bins from about 15 to 35–42. The models replicate all main features of the wave climate of the Baltic Sea, such as an overall mild but intermittent wave climate, the predominance of short windseas and the scarcity of long swell, east-west asymmetry, the strong impact of seasonal ice, and the specific properties of wave growth in some areas. The wave climate changes involve variations in regional wave intensity, core properties of wave-driven sediment transport and wave set-up. Reconstruction of wave properties in the nearshore, archipelago areas, and in narrow subbasins remains a challenge. These areas require finer spatial resolution and possibly advancement of wave physics to account for changes in the spectral composition of wave fields and specific features of wave growth in narrow basins. Progress in these fields is a pillar for a number of applications, from the quantification of sediment transport to proper input into management issues of the coastal zone.

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Long-term precipitation events in the eastern part of the Baltic Sea region
Oceanologia 2023, 65(1), 141-150
https://doi.org/10.1016/j.oceano.2022.02.003

Viktorija Mačiulytė (Viktorija Maciulyte)1,*, Egidijus Rimkus1, Donatas Valiukas2, Edvinas Stonevičius (Edvinas Stonevicius)1
1Institute of Geosciences, Vilnius University, Vilnius, Lithuania;
e-mail: viktorija.maciulyte@chgf.vu.lt
2Climate and Research Division, Lithuanian Hydrometeorological Service, Vilnius, Lithuania
*corresponding author

keywords: Precipitation, Rainy periods, Climate change, Baltic Sea region, Long-term precipitation events

Received 9 June 2021, Revised 22 October 2021, Accepted 18 February 2022, Available online 3 March 2022, Version of Record 3 March 2023.

Abstract

Precipitation anomalies have a significant impact on both natural environmental and human activity. Long lasting drought analysis has received great attention on a global and regional scale while prolonged rainy periods so far have been much less studied. However, long-term precipitation events are also important and threatening. The situation around the Baltic Sea in 2017 revealed that such periods could cause significant losses in agriculture.

The rainy periods of 30, 60, and 90 consecutive days in a given year during which the maximum precipitation amount was recorded in the eastern part of the Baltic Sea region were analysed in this study. Daily precipitation amount data from the E-OBS gridded dataset was used. The investigation covered a period from 1950 to 2019. The changes in magnitude and timing of such rainy periods were evaluated.

It was found that the annual precipitation in the eastern part of the Baltic Sea region increased significantly during the analysed period. Positive changes were observed throughout the year except during April and September. The amounts of precipitation during rainy periods of different duration also increased in most of the investigated areas but changes were mostly insignificant. Consequently, a decrease in the ratio of precipitation amount during the rainy period to annual precipitation was observed. It was also found that the rainy periods occurred earlier, especially in the case of the rainy periods of 60- and 90-days durations. Such tendencies pose an increasing threat to agriculture.

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Characteristics of seasonal changes of the Baltic Sea extreme sea levels
Oceanologia 2023, 65(1), 151-170
https://doi.org/10.1016/j.oceano.2022.02.006

Tomasz Wolski1,*, Bernard Wiśniewski2
1CSIR – Institute of Marine and Environmental Sciences, University of Szczecin, Szczecin, Poland;
e-mail: tomasz.wolski@usz.edu.pl
2Maritime University of Szczecin, Szczecin, Poland
*corresponding author

keywords: Storm surges, High and low sea levels, Seasonal changes, NAO, AO

Received 1 July 2021, Revised 25 October 2021, Accepted 18 February 2022, Available online 8 March 2022, Version of Record 3 March 2023.

Abstract

This work analyses the monthly spatial distribution of extreme sea levels in the Baltic Sea as well as the relationship of these levels with the NAO and AO indicators. The research was based on hourly sea level data from the 45 tide gauge stations gathered in the years 1960 to 2020. The analysis shows that the duration of extreme sea levels tends to increase moving from along the line joining the open sea and the gulf end. This is associated with the narrowing of the gulf and the geomorphological and bathymetric configuration of the coastal zone. The duration of high and low sea levels in the Baltic Sea decreases from a maximum in January to a minimum in the months of May to August, then it increases again until the end of the year. This cycle corresponds well to the annual occurrence of storm surges, which are affected by the annual changes in atmospheric circulation. The impact of the variations of the circulation on extreme sea levels was confirmed by examining the relation between maximum, minimum and mean levels of the Baltic waters and the zone circulation indices NAO and AO for each month of the year and the seasons in the multiyear period 1960–2020. The results indicate that the strongest correlations exist between sea levels and NAO/AO in the winter months. There is a spatial differentiation of the correlation and its increase from the southwest to the northeast in Baltic Sea.
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Seasonality and long-term trends of NDVI values in different land use types in the eastern part of the Baltic Sea basin
Oceanologia 2023, 65(1), 171-181
https://doi.org/10.1016/j.oceano.2022.02.007

Laurynas Klimavičius*, Egidijus Rimkus, Edvinas Stonevičius, Viktorija Mačiulytė
Institute of Geosciences, Vilnius University, Vilnius, Lithuania;
e-mail: laurynas.klimavicius@chgf.vu.lt
*corresponding author

keywords: NDVI, Growing season, Air temperature, Precipitation

Received 26 August 2021, Revised 15 February 2022, Accepted 24 February 2022, Available online 12 March 2022, Version of Record 3 March 2023.

Abstract

This study analyses changes in Normalized Difference Vegetation Index (NDVI) values in the eastern Baltic region. The main aim of the work is to evaluate changes in growing season indicators (onset, end time, time of maximum greenness and duration) and their relationship with meteorological conditions (air temperature and precipitation) in 1982–2015. NDVI seasonality and long-term trends were analysed for different types of land use: arable land, pastures, wetlands, mixed and coniferous forests. In the southwestern part of the study area, the growing season lasts longest, while in the northeast, the growing season is shorter on average by 10 weeks than in the other parts of the analysed territory. The air temperature in February and March is the most important factor determining the start of the growing season and the air temperature in September and October determines the end date of the growing season. Precipitation has a much smaller effect, especially at the beginning of the growing season. The effect of meteorological conditions on peak greenness is weak and, in most cases, statistically insignificant. At the end of the analysed period (1982–2015), the growing season started earlier and ended later (in both cases the changes were 3–4 weeks) than at the beginning of the study period. All these changes are statistically significant. The duration of the growing season increased by 6–7 weeks.
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Natural and anthropogenic influences on the development of mud depocenters in the southwestern Baltic Sea
Oceanologia 2023, 65(1), 182-193
https://doi.org/10.1016/j.oceano.2022.03.005

Lucas Porz1,*, Wenyan Zhang1, Corinna Schrum1,2
1Institute of Coastal Systems, Helmholtz-Zentrum Hereon, Geesthacht, Germany;
e-mail: lucas.porz@hereon.de
2Institute of Oceanography, Center for Earth System Research and Sustainability, University of Hamburg, Hamburg, Germany
*corresponding author

keywords: Baltic Sea, Bottom trawling, Mud depocenters, Sediment transport, Contourites, Bottom currents

Received 10 October 2021, Revised 2 March 2022, Accepted 21 March 2022, Available online 31 March 2022, Version of Record 3 March 2023.

Abstract

The morphological evolution of two mud depocenters in the southwestern Baltic Sea is investigated by comparison of numerical model results to geological and oceanographic data. The pathways of dense currents during episodic dense-water inflows from the North Sea are shown to correspond to current pathways inferred from contouritic depositional geometries in the flow-confining channels within the study area. A favorable comparison of model results to published current speed observations shows that the mesoscale dynamics of individual inflow events are reproduced by the model, indicating that external forcing and basin geometry rather than internal dynamics control the mesoscale dynamics of inflow events. The bottom current directions during inflows show high stability in the flow-confining channels and explain the contouritic depositional geometries. Asymmetric depositional features in the channels are qualitatively reproduced in the model. Bottom currents are less stable in areas without contouritic features, possibly resulting in an overall diffusive effect on sediment distribution in those areas. In a simulation of resuspension by bottom-contacting fishing gear, inter-basin sediment transport is increased by 4–30%, depending on the area, compared to the case of natural hydrodynamic resuspension. The model predicts an increased winnowing of the finest sediment fraction due to bottom trawling, leading to an overall coarsening-to-fining trend in the direction of net sediment transport. The results show that rather than hemi-pelagic background sedimentation, episodic events with high bottom current velocities as well as bottom-trawling induced resuspension are responsible for the present-day and future morphological configuration of the mud depocenters in the southwestern Baltic Sea.
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Photosynthetic signatures of microbial colonies covering submerged hard surfaces as novel trophic status indicators: Baltic Sea studies
Oceanologia 2023, 65(1), 194-201
https://doi.org/10.1016/j.oceano.2022.04.004

Katarzyna Boniewicz-Szmyt1,*, Maciej Grzegorczyk2, Stanisław J. Pogorzelski2, Paweł Rochowski2
1Department of Physics, Gdynia Maritime University, Gdynia, Poland;
e-mail: k.boniewicz@wm.umg.edu.pl
2Institute of Experimental Physics, Faculty of Mathematics, University of Gdańsk, Gdańsk, Poland
*corresponding author

keywords: Baltic biofilms, Trophic state indicators, Pigments mixture, Photosynthetic properties, Photoacoustic spectroscopy, Novel bioindicators

Received 7 April 2021, Revised 25 April 2022, Accepted 25 April 2022, Available online 5 May 2022, Version of Record 3 March 2023.

Abstract

The study aimed to determine photosynthetic signatures, i.e. photosynthetic energy storage (ES) efficiency and photoacoustic spectra of pigment-containing biofilm communities attached to submerged solid substrates in relation to the temporal variability of the trophic state of natural water. Biofouling phenomenon signatures on artificial solid surfaces, deployed in the shallow Baltic Sea waters (Gulf of Gdańsk, Poland) for a specific period of time, were determined over a three-year period using improved photoacoustic spectroscopy apparatus based on closed cell geometry. Selected chemical parameters (oxygen, nitrogen and phosphorus concentrations) and biological productivity (primary production and Chlorophyll a; hereinafter abbreviated as Chl a) of the water body were obtained from the SatBałtyk System platform (http://satbaltyk.iopan.gda.pl) and used as comprehensive data. As a result, close cross-correlations between photosynthetic energy storage and PAS amplitude spectra and the seawater chemical parameters were demonstrated. As found, ES was negatively correlated with concentrations of biogenic elements (correlation coefficient R given in brackets): O (–0.67), P (–0.81), N (–0.76), and positively correlated with concentrations of Chl a (0.82) and primary production (0.39). As periphyton is believed to respond dynamically to water quality and environmental stresses, its photosynthetic system features can be used as novel, modern and robust indicators in marine bioassessment, in addition to traditional trophic state indices based on chemical analysis.
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Rapid sea-level rise during the first phase of the Littorina transgression in the western Baltic Sea
Oceanologia 2023, 65(1), 202-210
https://doi.org/10.1016/j.oceano.2022.05.001

Karl Stattegger*, Karolina Leszczyńska
Institute of Geology, Adam Mickiewicz University, Poznań, Poland;
e-mail: karsta8@amu.edu.pl
*corresponding author

keywords: Baltic Sea, Relative sea-level rise, Littorina transgression, Meltwater pulse

Received 3 August 2021, Revised 8 April 2022, Accepted 16 May 2022, Available online 26 May 2022, Version of Record 3 March 2023.

Abstract

Glacio-isostatic adjustment (GIA) corrected limiting non-marine and marine sea-level data from the western Baltic Sea indicate a rapid relative sea-level (RSL) rise of 18 m for the first phase of the Littorina transgression using a linear age-elevation model. This accelerated RSL rise occurred in the time period 8.57 to 8.0 ka before present (BP) with an RSL rise rate of 31.5 mm/year. RSL rose from 28 m to 10 m below the mean relative sea level (bmrsl) during the time period of less than 600 years. The first phase of Littorina transgression documents the last big meltwater pulse (MWP), which has been reported also from various other regions in the world as a consequence of the final decay of the Laurentide ice sheet and additional meltwater sources from Antarctica.
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A fossil diatom-based reconstruction of sea-level changes for the Late Pleistocene and Holocene period in the NW South China Sea
Oceanologia 2023, 65(1), 211-229
https://doi.org/10.1016/j.oceano.2022.05.004

Jinpeng Zhang1,2,3,*, Michal Tomczak4, Andrzej Witkowski2, Xia Zhen1, Chao Li5
1Guangzhou Marine Geological Survey, China Geological Survey/Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), China;
e-mail: jinpenggmgs@sina.com
2Institute of Marine and Environmental Sciences, University of Szczecin, Poland
3State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, China
4Polish Geological Institute – National Research Institute, Warsaw, Poland
5College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
*corresponding author

keywords: Diatom, Transgression and regression, Sea-level changes, Paleoclimate, Holocene, Beibu Gulf

Received 30 August 2021, Revised 22 April 2022, Accepted 26 May 2022, Available online 9 June 2022, Version of Record 3 March 2023.

Abstract

Marine transgressions-regressions have profoundly shaped marginal seas following global sea-level fluctuations driven by climate change. This study on a sedimentary core profile SO219/31-4 from the Beibu Gulf, northwestern South China Sea (SCS), reveals information about paleoenvironment, paleoceanography and paleoclimate changes through fossil diatom assemblages and grain size distributions during the last ca. 12900 cal. yr. BP. Eight local diatom assemblage zones were distinguished and assigned to paleoenvironmental fluctuations recording sea-level and depositional environment changes in eight stages, ca. 12900–11700 (stage 1), ca. 11700–9500 (stage 2), ca. 9500–7200 (stage 3), ca. 7200–5800 (stage 4), ca. 5800–3800 (stage 5), ca. 3800–2400 (stage 6), ca. 2400–800 (stage 7) and ca. 800–0 (stage 8), cal. yr. BP. After the low sea level of stage 1 within the last deglaciation, rapid increases in sea level in stages 2 and 3 were recorded as meltwater events pulse-1B and pulse-1C resulting in marine transgression rates of ca. 16 m/kyr and 8 m/kyr, respectively. The high sea level, above the present level, in stages 4 and 5, in the Middle Holocene Climatic Optimum period, was clearly documented by more significant open sea/tropical diatom species and coastal planktonic species percentages, respectively. The late Holocene regression of sea levels was marked by a pronounced reversion of diatom taphocoenosis, responding to neoglacial climate. Fossil diatom assemblages outlined responded to paleoclimate of global warming in the deglacial and early Holocene. This study provides additional insights into the late Pleistocene and Post-glacial history of a tropical-subtropical shallow water gulf, in the NW-SCS.
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Complementing ERA5 and E-OBS with high-resolution river discharge over Europe
Oceanologia 2023, 65(1), 230-248
https://doi.org/10.1016/j.oceano.2022.07.003

Stefan Hagemann1,*, Tobias Stacke1,2
1Institute of Coastal Systems – Analysis and Modelling, Helmholtz-Zentrum Hereon, Geesthacht, Germany;
e-mail: stefan.hagemann@hereon.de
2Max Planck Institute for Meteorology, Hamburg, Germany
*corresponding author

keywords: Discharge trends, High resolution, Europe, ERA5, E-OBS

Received 9 August 2021, Revised 13 July 2022, Accepted 22 July 2022, Available online 5 August 2022, Version of Record 3 March 2023.

Abstract

The 0.5° resolution of many global observational or quasi-observational datasets is not sufficient for the evaluation of current state-of-the-art regional climate models or the forcing of ocean model simulations over Europe. While higher resolved products are available for meteorological data, e.g. ERA5 reanalysis and the E-OBS vs 22 (EOBS22) datasets, they lack crucial information at the land-ocean boundary. ERA5 is frequently used to force regional climate models (RCMs) or ocean models and both datasets are commonly used as reference datasets for the evaluation of RCMs. Therefore, we extended both datasets with high-resolution river discharge for the period 1979–2018. On the one hand, our discharge data close the water cycle at the land-ocean interface so that the discharges can be used as lateral freshwater input for ocean models applied in the European region. On the other hand, the data can be used to identify trends in discharge that are induced by recent climate change as ERA5 and EOBS22 are rather independent datasets. The experimental setup to generate the discharges was chosen in a way that it could be easily adapted in a climate or Earth system modelling framework. Consequently, the recently developed 5 Min. horizontal resolution version of the hydrological discharge (HD) model was used to simulate discharge. It has already been applied in multiple climate modelling studies and is coupled within several global and regional Earth system models. As the HD model currently does not regard direct human impacts of the river runoff, it is well suited to investigate climate change-related discharge trends. In order to calculate the necessary gridded input fields for the HD model from ERA5 and EOBS22 data, we used the HydroPy global hydrological model. For both experiments, we found that the general behavior of discharge is captured well for many European rivers, which is consistent to earlier results. For the EOBS22 based discharges, a widespread low bias in simulated discharge occurs, which is likely caused by the missing undercatch correction in the underlying precipitation data. The analysis of trends over Southeastern Europe was hampered by missing data in EOBS22 after 2004. Using both experiments, we identified consistent trend patterns in various discharge statistics, with increases in low flow characteristics over Northern Europe and general drying trends over Central and Southern Europe. In summary, we introduced an experimental setup that is useful to generate high-resolution river runoff data consistent with the meteorological forcing for historical periods and future scenarios from any climate model data instead of having to rely on observed time series.
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Relative sea-level changes induced by glacial isostatic adjustment and sediment loads in the Beibu Gulf, South China Sea
Oceanologia 2023, 65(1), 249-259
https://doi.org/10.1016/j.oceano.2022.09.001

Andreas Groh1,*, Jan Harff2,*
1Institute of Planetary Geodesy, Technical University of Dresden, Germany;
e-mail: andreas.groh@tu-dresden.de
2Institute of Marine and Environmental Sciences, University of Szczcecin, Poland
e-mail: jan.harff@io-warnemuende.de
*corresponding author

keywords: Relative sea level, Solid Earth deformation, Sediment loading, Glacial isostasy, Sea-level equation

Received 9 October 2021, Revised 6 September 2022, Accepted 9 September 2022, Available online 22 September 2022, Version of Record 3 March 2023.

Abstract

We modelled changes in relative sea level (RSL) in the Beibu Gulf region, South China Sea, caused by the melting of the Pleistocene ice sheets, i.e., glacial isostatic adjustment (GIA). Both the temporal evolution of RSL between the last glacial maximum and present day as well as present-day rates were derived. The interplay of changing ocean water volume, gravitational induced water redistribution and solid Earth deformations due to the varying surface loads is accounted for by means of the sea-level equation. The modelled RSL curves for the Beibu Gulf region reveal the shape typical for regions far away from the former centres of glaciation, exhibiting a pronounced Holocene sea-level highstand between 4 and 5 kyr before the present. A general good agreement was found between modelled and empirical RSL curves, although differences in the timing and magnitude of the highstand were revealed. In addition to GIA-induced RSL, we also modelled the effect of RSL variations due to sediment accumulation during marine isotopic stages MIS 4 to MIS 1 descending mainly from Hainan Island, but also other terrestrial sources from the Chinese (and Vietnamese) mainland. Estimates for the sediment loading originate from seismic surveys and dated sediment cores. We found that RSL changes caused by sediment loading are at least three orders of magnitude smaller than those induced by GIA. The present-day rates of both RSL effects are too small to be detectable by geodetic observations and cannot be discriminated from prominent tectonic signals.
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A Marine Spatial Data Infrastructure to manage multidisciplinary, inhomogeneous and fragmented geodata in a FAIR perspective — the Adriatic Sea experience
Oceanologia 2023, 65(1), 260-277
https://doi.org/10.1016/j.oceano.2022.11.002

Federica Foglini, Valentina Grande*
National Research Council (CNR), Institute of Marine Sciences (ISMAR), Bologna, Italy;
e-mail: valentina.grande@bo.ismar.cnr.it
*corresponding author

keywords: FAIR principles, Marine Spatial Data Infrastructure, Data model, WebGIS, Metadata catalogue, Adriatic Sea

Received 26 August 2021, Revised 28 September 2022, Accepted 15 November 2022, Available online 2 December 2022, Version of Record 3 March 2023.

Abstract

The Institute of Marine Sciences (ISMAR) and the Institute of Polar Sciences (ISP) of the Italian National Research Council (CNR) have gathered a substantial amount of heterogeneous geodata through the years in the Adriatic Sea, with different methodologies and for multiple scopes regarding geological, oceanographic, biological, anthropogenic aspects, and their interactions.
To overcome challenges in datasets heterogeneity and fragmentation, a Marine Spatial Data Infrastructure (MSDI) has been set up, with the aim to integrate and preserve geodata, foster their reuse (e.g. the generation of scenarios for geological past and future developments by the application of numerical models), and ensure a good degree of FAIRness (FAIR: Findable, Accessible, Interoperable, and Reusable). The MSDI consists of a Spatial Relational Database Management System (RDBMS) based on specific data models designed following in part the INSPIRE Directive data specifications, a WebGIS, a metadata catalogue, and a cloud system. This paper shows the potentialities of this MSDI and discusses the main implementation steps, the elements that make up the infrastructure, the level of FAIRness reached, the main elements promoting FAIRness, and the gaps to be covered.
Compliance with the FAIR principles represents a fundamental step to developing interoperability with European and international marine data management infrastructures for handling and exchanging multidisciplinary data.
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Biogeochemistry-ecosystem-social interactions on the Chinese continental margins
Oceanologia 2023, 65(1), 278-296
https://doi.org/10.1016/j.oceano.2022.12.001

Su Mei Liu1,2,*, Wen Liang1, Xinyu Guo3, Nian Wu1,2, Wuchan Zhang2,4, Xiujuan Shan5, Hua-De Zhao6, Juying Wang6, Jin Huang1
1Frontiers Science Center for Deep Ocean Multispheres and Earth System, and Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, China;
e-mail: sumeiliu@ouc.edu.cn
2Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
3Center for Marine Environmental Studies, Ehime University, Matsuyama, Japan
4Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
5Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture and Rural Affairs, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China
6National Marine Environmental Monitoring Center, Dalian 116023, China
*corresponding author

keywords: Drivers, Pressures, Environmental change, Social response, Bohai

Received 9 December 2021, Revised 28 November 2022, Accepted 1 December 2022, Available online 15 December 2022, Version of Record 3 March 2023.

Abstract

Chinese continental margins are experiencing remarkable environmental changes driven by anthropogenic activities and climate change. As an important habitat and sea-based fish farming resource in China, the Bohai was selected as a case study to understand how ecosystems and social interactions are influenced by multi-stressors. The Bohai ecosystem has been considerably modified. The Bohai coastline has been significantly changed (e.g., total sea area decreased and morphology changed) by sea reclamation and riverine sediment transport related to agriculture and erosion. Therefore, the strict reclamation policy and “Grain-for-Green” program have been issued to protect the coastline. Nutrient concentrations and composition have been changed by fertilizer application, wastewater discharge, and variations in seasonal patterns of riverine nutrient fluxes. Hence, pollution control and prevention are necessary. More seriously, fishing resources have been altered, as a result of environmental changes and overfishing. Therefore, a summer fishing ban and stock enhancement should be vital besides environmental improvement. This study can help to predict and mitigate impacts on global continental margins that are experiencing similar environmental stress.
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