Oceanologia No. 60 (1 / 18)


Contents


Acknowledgements



Original research article


Short communications


Original research article



Total suspended particulate matter in the Porsanger fjord (Norway) in the summers of 2014 and 2015
Oceanologia 2018, 60(1), 1-15
https://doi.org/10.1016/j.oceano.2017.06.002

Jagoda Białogrodzka1,2,*, Małgorzata Stramska1,2, Dariusz Ficek3, Marzena Wereszka1
1Department of Earth Sciences, Szczecin University, Szczecin, Poland;
e-mail: jbialogrodzka@iopan.gda.pl, jagoda.bialogrodzka@gmail.com
*corresponding author
2Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland
3Department of Environmental Physics, Pomeranian University in Słupsk, Słupsk, Poland

keywords: Arctic; Porsanger fjord; Suspended matter; Optical measurements

Received 29 December 2016, Accepted 19 June 2017, Available online 6 July 2017.

Abstract

High-latitude fjords, very vulnerable to global change, are impacted by their land and ocean boundaries, and they may be influenced by terrestrial water discharges and oceanic water inputs into them. This may be reflected by temporal and spatial patterns in concentrations of biogeochemically important constituents. This paper analyses information relating to the total suspended matter (TSM) concentration in the Porsanger fjord (Porsangerfjorden), which is situated in the coastal waters of the Barents Sea. Water samples and a set of physical data (water temperature, salinity, inherent optical properties) were obtained during two field expeditions in the spring and summer of 2014 and 2015. Bio-optical relationships were derived from these measurements, enabling optical data to be interpreted in terms of TSM concentrations. The results revealed significant temporal variability of TSM concentration, which was strongly influenced by precipitation, terrestrial water discharge and tidal phase. Spatial distribution of TSM concentration was related to the bathymetry of the fjord, dividing this basin into three subregions. TSM concentrations ranged from 0.72 to 0.132 g m−3 at the surface (0–2 m) and from 0.5 to 0.67 g m−3 at 40 m depth. The average mineral fraction was estimated to be 44% at surface and 53% at 40 m.
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Attributing mean circulation patterns to physical phenomena in the Gulf of Finland
Oceanologia 2018, 60(1), 16-31
https://doi.org/10.1016/j.oceano.2017.05.003

Antti Westerlund1,*, Laura Tuomi1, Pekka Alenius1, Elina Miettunen2, Roman E. Vankevich3
1Finnish Meteorological Institute, Marine Research, Helsinki, Finland;
e-mail: antti.westerlund@fmi.fi
*corresponding author
2Finnish Environment Institute/Marine Research Centre, Helsinki, Finland
3Russian State Hydrometeorological University, Saint Petersburg, Russia

keywords: Circulation; Upwelling, Modelling; Baltic Sea; Gulf of Finland

Received 15 September 2016, Accepted 19 May 2017, Available online 12 June 2017.

Abstract

We studied circulation patterns in the Gulf of Finland, an estuary-like sub-basin of the Baltic Sea. According to previous observations and model results, the long-term mean circulation in the gulf is cyclonic and mainly density driven, whereas short-term circulation patterns are wind driven. We used the high-resolution 3D hydrodynamic model NEMO to simulate the years 2012–2014. Our aim was to investigate the role of some key features, like river runoff and occasional events, in the formation of the circulation patterns. Our results show that many of the differences visible in the annual mean circulation patterns from one year to another are caused by a relatively small number of high current speed events. These events seem to be upwelling-related coastal jets. Although the Gulf of Finland receives large amounts of fresh water in river runoffs, the inter-annual variations in runoff did not explain the variations in the mean circulation patterns.
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Modeling the ecosystem response to summer coastal upwelling in the northern South China Sea
Oceanologia 2018, 60(1), 32-51
https://doi.org/10.1016/j.oceano.2017.05.004

Rui Jiang1,2, You-Shao Wang1,3,*
1State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
2University of Chinese Academy of Sciences, Beijing, China;
e-mail: yswang@scsio.ac.cn
*corresponding author 3Daya Bay Marine Biology Research Station, Chinese Academy of Sciences, Shenzhen, China

keywords: The northern South China Sea; NPZD ecosystem model; Summer coastal upwelling; Coastal ecosystem

Received 19 October 2016, Accepted 19 May 2017, Available online 15 June 2017.

Abstract

A coupled three-dimensional physical model and a nitrogen-based nutrient, phytoplankton, zooplankton, and detritus (NPZD) ecosystem model were applied to simulate the summer coastal upwelling system over the continental shelf of northern South China Sea (NSCS) and its impact on hydrographic conditions and ecosystem. The simulated results were comprehensively validated against field and satellite measurements. The model results show that the near shore ecosystem of NSCS has significant responses to the summer coastal upwelling system. The Shantou Coast to the Nanri Islands of Fujian province (YD) and the east of the Leizhou Peninsula (QD) are two main regions affected by NSCS summer coast upwelling. During summer, these two coastal areas are characterized by nearshore cold and high salinity upwelling current. Further, the summer coastal upwelling serves as a perfect nutrient pump, which lifts up and advects nutrient-rich current from deep to surface, from inner shelf to about 30 km outer shelf. This nutrient source reaches its maximum in the middle of July and then begins to decrease. However, the maximum phytoplankton and chlorophyll a do not coincide with the maximum nutrients and delay for about 10 days. Because of the intensive seasonal thermocline and the complicated current transporting through Qiongzhou strait, the ecological responding of QD is less pronounced than YD. This study has a better understanding of the physically modulated ecological responses to the NSCS summer coastal upwelling system.
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Identifying the main sources of silicate in coastal waters of the Southern Gulf of Valencia (Western Mediterranean Sea)
Oceanologia 2018, 60(1), 52-64
https://doi.org/10.1016/j.oceano.2017.07.004

Javier Sospedra1,*, L. Felipe H. Niencheski2, Silvia Falco1, Carlos F. F. Andrade2, Karina K. Attisano3, Miguel Rodilla1
1Institut d’Investigació per a la Gestió Integrada de Zones Costaneres (IGIC), Universitat Politècnica de València, Grau de Gandia, Spain;
e-mail: jasoscis@epsg.upv.es
*corresponding author
2Instituto de Oceanografia, Universidade Federal do Rio Grande, Rio Grande, Brazil
3Centro CEP, Campus São Lourenço do Sul, Universidade Federal do Rio Grande, São Lourenço do Sul, Brazil

keywords: Silicon; Silicate flux; Silicon balance; Biogenic silica; Submarine groundwater discharge; Nutrient

Received 31 January 2017, Accepted 17 July 2017, Available online 1 August 2017.

Abstract

Silicon is a major nutrient for siliceous primary producers, which can become a potential limiting nutrient in oligotrophic areas. Most of the silicon inputs to the marine environment come from continental discharges, from both superficial and ground waters. This study analyses the main sources of silicon and their dynamics along the southernmost 43 km of shoreline in the Gulf of Valencia (Western Mediterranean Sea). The salinity and silicate concentration in the different compartments (springs, freshwater wells, beach groundwater, surf zone and coastal waters) in this coastal area were determined. In addition, chlorophyll a and phytoplankton community were analyzed in the surf zone and coastal waters. Silicate concentrations in freshwater wells ranged between 130 and 150 μM, whereas concentrations of this nutrient declined to 49 μM in freshwater–seawater mixture transects. At the same time, there was a positive gradient in silicate for both freshwater and coastal waters southward. An amount of 18.7 t of dissolved silicate was estimated in the nearest first kilometre nearest to the coastline, 6 t of this silicate belonged to the background sea level. On the other hand, the sum of the main rivers in the area supplies 1.6 t of dissolved silicate per day. This implies that a large amount of the remaining 11.1 t must derive from submarine groundwater discharges, which would thus represent 59% of the coastal dissolved silicate budget. Overall, it is suggested that a subterranean transport pathway must contribute considerably to silicate concentrations throughout this zone, which is characterized as permeable.
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Inherent optical properties and particulate matter distribution in summer season in waters of Hornsund and Kongsfjordenen, Spitsbergen
Oceanologia 2018, 60(1), 65-75
https://doi.org/10.1016/j.oceano.2017.07.006

Sławomir Sagan*, Mirosław Darecki
Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland;
e-mail: sagan@iopan.gda.pl
*corresponding author

keywords: Optical properties; Particles; Hornsund; Kongsfjordenen

Received 23 July 2016, Accepted 26 July 2017, Available online 12 August 2017.

Abstract

Two Spitsbergen fjords, Hornsund and Kongsfjorden, are known for being under different hydrological regimes. The first is cold, separated from warm Atlantic water by East Spitsbergen Current, while Kongsfjorden is frequently penetrated by relatively warm Atlantic water. On the other hand, both are under strong influence of water discharge from glaciers and land freshwater input. During the period of observation in both fjords a dominant water mass was Surface Water, which originates mainly from glacial melt. The presence of suspended matter introduced with melt water in Surface Water is reflected by highest values of light attenuation and absorption coefficients recorded in areas close to glacier both in Hornsund and Kongsfjorden. In Hornsund the maximum light attenuation coefficient cpg(555) was 5.817 m−1 and coefficient of light absorption by particles ap(676) = 0.10 m−1. In Kongsfjorden the corresponding values were 26.5 m−1 and 0.223 m−1. In Kongsfjorden suspended matter of the size class 20–200 μm dominated over fractions smaller than 20 μm while in Hornsund dominating size fraction was 2–20 μm. The results provide an evidence of considerable range of variability of the optical properties mainly due to glacial and riverine runoff. The scale of variability of particulate matter in Kongsfjorden is bigger than in Hornsund. Most of the variability in Hornsund can be attributed to glaciers discharge and a presence of particles of mineral origin, while in Kongsfjorden the organic and mineral particles contribute almost equally to defining the optical properties of water.
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Spatio-temporal variability in the Brazil-Malvinas Confluence Zone (BMCZ), based on spectroradiometric MODIS-AQUA chlorophyll-a observations
Oceanologia 2018, 60(1), 76-85
https://doi.org/10.1016/j.oceano.2017.08.002

Luciano Telesca1,*, Jorge O. Pierini2, Michele Lovallo3, Eduardo Santamaría-del-Angel4
1National Research Council, Institute of Methodologies for Environmental Analysis, Tito, PZ, Italy;
e-mail: luciano.telesca@imaa.cnr.it
2 Comisión de Investigaciones Científicas (CIC) – IADO-CONICET, Bahía Blanca, Argentina
3ARPAB, Potenza, Italy
4Universidad Autónoma de Baja California, Baja California, Mexico

keywords: MODIS Ocean color spectroradiometric chlorophyll-a; Remote sensing oceanography; Statistics

Received 28 March 2017, Accepted 7 August 2017, Available online 26 August 2017.

Abstract

The Brazil–Malvinas Confluence Zone (BMCZ) is characterized by high environmental variation, which could be reflected in several optical types of water, from one containing only phytoplankton and sea water to other optically more complex. In this paper, we analyze the spatio-temporal variability of the Chlorophyll-a detected by the ocean color sensor (CHLAsat) in BMCZ in order to understand its environmental variability. We use the MODIS-Aqua CHLAsat monthly composites imagery from 2002 to 2015, and applied two statistical methods: the correlogram-based robust periodogram to identify, over a broad spectrum of temporal, the most significant periodicities, and the pixel gradient distribution to study the spatial-temporal gradients within the BMCZ and variations over the continental shelf and coastal waters. Our results point out to the predominance of the annual cycle over most of the investigated area, although an area from latitude 37°S in direction NE, alongshore of Uruguay to Brazil, evidences interannual periodicities, possibly related to variations in the discharge of the Rio de la Plata associated with the El Niño phenomena. The ocean color spectroradiometric signature in terms of pixel gradient presents a relatively high variability (∼0.0 to 0.65 mg m−3); in particular the high values of the pixel gradient correspond to saline front of the estuarine system of Rio de la Plata, and to the strip of the platform that extends along the isobaths of 80 m (coast of Uruguay), especially in the center and south of the study area.
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Laboratory measurements of remote sensing reflectance of selected phytoplankton species from the Baltic Sea
Oceanologia 2018, 60(1), 86-96
https://doi.org/10.1016/j.oceano.2017.08.001

Monika Soja-Woźniak1,2,3,*, Mirosław Darecki4, Bożena Wojtasiewicz1,5, Katarzyna Bradtke1
1Institute of Oceanography, University of Gdańsk, Poland;
e-mail: monika@soja-wozniak.com
*corresponding author
e-mail: bozena.wojtasiewicz@ug.edu.pl
e-mail: katarzyna.bradtke@ug.edu.pl
2Department of Space, Earth and Environment, Chalmers University of Technology, Gothenburg, Sweden
3CSIRO Oceans & Atmosphere, Hobart, TAS, Australia
4Institute of Oceanology Polish Academy of Sciences, Sopot, Poland;
e-mail: darecki@iopan.gda.pl
5CSIRO Oceans & Atmosphere, Crawley, WA, Australia

keywords: Phytoplankton monoculture; Laboratory measurements; Remote sensing reflectance

Received 19 May 2017, Accepted 8 August 2017, Available online 26 August 2017

Abstract

Results of unique laboratory measurements of remote sensing reflectance (Rrs) of several phytoplankton species typically occurring in high abundances in the Baltic Sea waters are presented. Reflectance spectra for diatoms: Cyclotella meneghiniana and Skeletonema marinoi and Dolichospermum sp., Nodularia spumigena and sp. were analysed in terms of assessment of their characteristic features and the differences between them. These species contain similar pigments, which results in general similarities of reflectance spectra, i.e. decrease of reflectance magnitude in the blue and red spectrum regions. However, hyper-spectral resolution of optical measurements let us find differences between optical signatures of diatoms and cyanobacteria groups and between species belonging to one group as well. These differences are reflected in location of local maxima and minima in the reflectance spectrum and changes in relative height of characteristic peaks with changes of phytoplankton concentration. Wide ranges of phytoplankton concentrations were analysed in order to show the persistence of Rrs characteristic features. The picoplankton species, Synechococcus sp. show the most distinct optical signature, which let to distinguish separate cluster in hierarchical cluster analysis (HCA). The results can be used to calibrate input data into radiative transfer model, e.g. phase function or to validate modelled Rrs spectra.
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Live autochthonous benthic diatoms on the lower depths of Arctic continental shelf. Preliminary results
Oceanologia 2018, 60(1), 97-100
https://doi.org/10.1016/j.oceano.2017.07.001

Elena Druzhkova*, Anatoliy Oleinik, Pavel Makarevich
Murmansk Marine Biological Institute, Kola Scientific Centre, Russian Academy of Sciences, Murmansk, Russia;
e-mail: druzhkova.elena@yandex.ru
*corresponding author

keywords: Microphytobenthos; Arctic continental shelf; Diatoms

Received 6 April 2017, Accepted 4 July 2017, Available online 21 July 2017.

Abstract

An autochthonous community of benthic diatoms was discovered in June 2015 in the upper sediment layer at depths of 170, 205, and 245 m in the central Barents Sea. At least three benthic microalgae species (Gyrosigma fasciola, Pleurosigma angulatum, and Pleurosigma sp. 1) were detected in the sediment but not the upper water column. Analyses revealed that these benthic microalgae represent a depleted fragment of Arctic littoral microphytobenthos. Compared with the littoral flora, the deep-water assemblage is less diverse and displays low abundance. The data reported here challenge the generally accepted belief that the presence of certain microalgae at significant depths results from vertical or horizontal transfer.
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First records of two planktonic Indo-Pacific diatoms: Chaetoceros bacteriastroides and C. pseudosymmetricus in the Adriatic Sea
Oceanologia 2018, 60(1), 101-105
https://doi.org/10.1016/j.oceano.2017.07.005

Marijeta Čalić1,*, Stijepo Ljubimir1, Sunčica Bosak2, Ana Car1
1Institute for Marine and Coastal Research, University of Dubrovnik, Dubrovnik, Croatia;
e-mail: marijeta.calic@unidu.hr
*corresponding author
2Department of Biology, Faculty of Science, University of Zagreb, Zagreb, Croatia

keywords: Bacillariophyta; Chaetoceros; Introduced species; Mediterranean; Phytoplankton; Tropical

Received 21 April 2017, Accepted 18 July 2017, Available online 3 August 2017.

Abstract

Unusual occurrence of planktonic diatom species, Chaetoceros bacteriastroides and Chaetoceros pseudosymmetricus, was noticed in three different marine ecosystems of Adriatic Sea: the Krka Estuary and Telaščica Bay in the Central Adriatic, and in southern Adriatic offshore. From 2010 to 2015, these two Chaetoceros species were recorded in heterogeneous environmental conditions and in a very low abundances. Both species are regarded as very rare in world oceans, and consequently knowledge of their distribution and ecology is rather poor. Primarily described from tropical waters and showing Indo-Pacific distribution, C. bacteriastroides and C. pseudosymmetricus findings in Adriatic represent the northernmost records in world's oceans and seas. For C. pseudosymmetricus this is also the first occurrence in European seas. Areal expansion and introduction of new phytoplankton species in the Adriatic Sea might be related to different circulation regimes in the Ionian Sea and the concurrent rise in sea temperature in the Mediterranean in the last decade. Recent investigations have shown that entering currents, of either Atlantic/Western Mediterranean or Eastern Mediterranean origin, modify the composition of the plankton community in the Adriatic by bringing different newcomers.
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