Oceanologia No. 61 (4 / 19)


Contents


Original research article

Short communication


Original research article



Tide and mean sea level trend in the west coast of the Arabian Gulf from tide gauges and multi-missions satellite altimeter
Oceanologia 2019, 61(4), 401-411
https://doi.org/10.1016/j.oceano.2019.05.003

Nada Abdulraheem Siddig*, Abdullah Mohammed Al-Subhi, Mohammed Ali Alsaafani
Department of Marine Physics, Faculty of Marine Sciences, King Abdulaziz University, Jeddah, Saudi Arabia;
e-mail: nsiddique@stu.kau.edu.sa
*corresponding author

keywords: Sea level change, Long term data, Tidal constituents, Residual mean sea level, Arabian gulf costal region

Received 17 December 2018, Accepted 8 May 2019, Available online 24 May 2019.

Abstract

Hourly data of the relative sea level from seven stations on the west coast of the Arabian Gulf, for the period 1979–2008 have been analyzed. The harmonic constituents of tide show pure diurnal tide at Murjan Island, semidiurnal type at Mina Salman and mixed type with semidiurnal dominance at the remaining five stations. Based on Multi-Missions Satellite Altimetry data, the mean sea level trend estimate was about 2.8 ± 0.4 mm/year for global ocean and about 3.6 ± 0.4 mm/year for the Arabian Gulf. Among the seven tide gauge stations, the highest sea level trend is found at Mina Salman (3.4 ± 0.98 mm/year) that agrees with the local estimate from the Multi-Missions Satellite Altimetry data. The minimum trend is found at Jubail (1.6 ± 0.71 mm/year) and Ras Tanura (0.7 ± 0.31 mm/year). At Arrabiyah Island station, the sea level trend is about 2.4 ± 0.66 mm/year, which is obtained after removing the interruptions from a relatively longer duration (15 years) data. This is in agreement with other stations and the estimates from the altimetry. The tidal analysis and trend estimation for Jubail station (29 years) have been conducted for the first time. At Murjan Island, the decadal cycle is evident from the long sea level data, giving the current estimate of trend more reliability as compared with previous studies.
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Assessment of coastal vulnerability in Chabahar Bay due to climate change scenarios
Oceanologia 2019, 61(4), 412-426
https://doi.org/10.1016/j.oceano.2019.03.001

Mahmoudreza Armanfar1, Hamid Goharnejad1,3,4,*, Mahmoud Zakeri Niri2, Will Perrie3
1Environmental Sciences Research Center, IslamShahr Branch, Islamic Azad University, IslamShahr, Iran;
e-mail: Hgn1982@gmail.com
2Young Researchers and Elite Club, IslamShahr Branch, Islamic Azad University, IslamShahr, Iran
3Fisheries and Oceans Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, Canada
4Engineering Mathematics and Internetworking, Dalhousie University, Halifax, Nova Scotia, Canada
*corresponding author

keywords: Climate change, Sea level rise, Wave regime prediction, Coastal vulnerability, MIKE21 model

Received 2 October 2018, Accepted 7 March 2019, Available online 21 March 2019.

Abstract

A substantial body of research has shown that two key factors of global sea level rise are thermal expansion and melting of land-based ice, glaciers and ice sheets. Moreover, climate change may result in changes to wind speeds and directions, consequently resulting in contributions to variations in wind-wave components, wave heights and directions. In this research, climate change scenarios were used to assess the coastal vulnerability to the Chabahar port area due to global sea level rise, significant wave height changes and tidal regime effects. These three items were calculated separately using numerical models and the impacts of possible climate change scenarios were applied to estimate possible changes to these items by 2100. Significant wave heights for 25, 50 and 100-year return periods were evaluated. Based on statistical analysis, the maximum significant wave heights for the A2 and A1B scenarios were estimated at approximately 13.7 and 7.6, respectively. Since the main aim of this research was to assess the coastal zones at higher flood risk, therefore the mean global sea level rise, extreme values of significant wave heights and tidal heights were investigated. The height of sea during sea storms and for the most extreme case was calculated as 17.3 m and 11.2 m for A2 and the A1B scenarios, respectively. According to output maps of inundation areas, large coastal zones in the Chabahar port area are at risk due to the sea storms and possible climate change.
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Spatio-temporal variations in sulfur-oxidizing and sulfate-reducing bacterial activities during upwelling, off south-west coast of India
Oceanologia 2019, 61(4), 427-444
https://doi.org/10.1016/j.oceano.2019.03.002

A. Sam Kamaleson1, Maria-Judith Gonsalves1,*, Swatantar Kumar2, V. K. Jineesh3, P. A. LokaBharathi1
1CSIR-National Institute of Oceanography, Dona Paula, Goa, India;
e-mail: mjudith@nio.org
2International Max Planck Research School of Global Biogeochemical Cycles, Friedrich Schiller University, Jena, Germany
3Academy of Climate Change, Education and Research, Agricultural University, Kerala, India
*corresponding author

keywords: Sulfate-reduction, Sulfur-oxidation, Environmental parameters, Upwelling phases, South-west coast of India, Arabian Sea

Received 15 October 2018, Accepted 13 March 2019, Available online 8 April 2019.

Abstract

The Arabian Sea, off SW India, is becoming more anoxic in recent years. Poor ventilation affects microbial degradation of organic matter in the oxygen minimum zone (≤2.85 ml l−1 O2, ≤0.02 μM NO2) and the anoxic marine zone (≤0.09 ml l−1 O2, ≥0.5 μM NO2). We posit that one of the reasons at the microbial level could be due to a more prominent increase in sulfate-reducing activity (SRA), than sulfur-oxidizing activity (SOA). Hence, the objective was to measure the extent to which SOA can counter the effect of SRA. We, therefore examined these activities along with relevant environmental variables from 2009 to 2011 off Kochi (9.55°N–75.33°E) and Trivandrum (8.26°N–76.50°E), covering the three phases of upwelling. SRA was measured radiometrically using 35S, and SOA by iodometry. Off Kochi, the SOA of the water column increased 6× (194–1151 μM d−1) and SRA 4× (13–54 nM d−1) from phase I to III. Off Trivandrum, the increase in SOA was 1.7× (339–560 μM d−1) and SRA 7× (24–165 nM d−1) contributing to the build-up of reducing/oxidizing conditions. This increase in SOA moderates the effect of increase in SRA. Besides, the average concentrations of dissolved oxygen and nitrite off Trivandrum were 1.80 ± 1.66, 1.48 ± 1.55, 1.93 ± 1.86 ml l−1 and 0.14 ± 0.14, 1.69 ± 0.67, 0.34 ± 0.42 μM during the three phases respectively. Hence, it is suggested that the coastal waters examined in this study could probably be between oxygen minimum zone (OMZ) and anoxic minimum zone (AMZ) in patches temporarily. The present paper highlights the interactions between sulfate-reducing and sulfur-oxidizing activities, during upwelling for the first time in these waters. These observations give an important and timely insight into the implications.
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Reflectance spectra classification for the rapid assessment of water ecological quality in Mediterranean ports
Oceanologia 2019, 61(4), 445-459
https://doi.org/10.1016/j.oceano.2019.04.001

Luca Massi1,*, Fabio Maselli1,2, Claudia Rossano1, Simone Gambineri1, Evangelia Chatzinikolaou3, Thanos Dailianis3, Christos Arvanitidis3, Caterina Nuccio1, Felicita Scapini1, Luigi Lazzara1
1Department of Biology, University of Florence, Italy;
e-mail: imen.turki@univ-rouen.fr, nicolas.massei@univ-rouen.fr, benoit.laignel@univ-rouen.fr
2DBIMET CNR, Florence, Italy
3Hellenic Centre for Marine Research, Institute of Marine Biology, Biotechnology and Aquaculture, Heraklion, Greece
*corresponding author

keywords: Spectral reflectance, Water quality indicators, Light attenuating substances, Monitoring ecological status, Rapid assessment techniques, Optical classification of waters

Received 8 November 2018, Accepted 5 April 2019, Available online 30 April 2019.

Abstract

Ports are open systems with direct connection to the sea, therefore any potential impact on port waters may have implications for the health of adjacent marine ecosystems. European WFD addressed ports in the category of Heavily Modified Water Bodies (HMWBs) and promoted implementation of protocols to monitor and improve their ecological status. TRIX index, which incorporates the main variables involved in the trophism of marine ecosystems (Nitrogen, Phosphorus, Chlorophyll a, Dissolved Oxygen), is widely utilized in European coastal areas to evaluate trophic status. The relationships between the variables involved in TRIX computation, particularly Chlorophyll a concentration, and water spectral reflectance provides an alternative method to evaluate the quality and ecological status of the port water. Hyperspectral (380–710 nm) water reflectance data were recorded by a portable radiometric system in five ports from the Western and Eastern Mediterranean Basin. The spectral distance between samples was measured by two metrics using both the original and reduced spectra and was implemented within a hierarchical clustering algorithm. The four spectral classes that emerged from this operation were statistically analysed versus standard water quality descriptors and phytoplankton community features to evaluate the ecological significance of the information obtained. The results indicated a substantial coherence of different indicators with more than 60% of the total TRIX variability is accounted for by the proposed classification of reflectance spectra. This classification is therefore proposed as a promising Rapid Assessment Technique of ports water ecological quality, which can serve as an effective monitoring tool for sustainable management of ports.
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Gas transfer velocities in Norwegian fjords and the adjacent North Atlantic waters
Oceanologia 2019, 61(4), 460-470
https://doi.org/10.1016/j.oceano.2019.04.002

Hanne M. Banko-Kubis, Oliver Wurl, Nur Ili Hamizah Mustaffa, Mariana Ribas-Ribas*
Center for Marine Sensors, Institute for Chemistry and Biology of the Marine Environment, Carl von Ossietzky University of Oldenburg, Wilhelmshaven, Germany;
e-mail: mariana.ribas.ribas@uol.de
*corresponding author

keywords: Air-sea CO2 flux, Gas transfer velocity, Gas exchange, Parameterization, Fjord

Received 17 December 2018, Accepted 12 April 2019, Available online 1 May 2019.

Abstract

We investigated air-sea carbon dioxide (CO2) transfer in situ to determine the role of wind and turbulence in forcing gas transfer. In situ gas transfer velocities of CO2 were measured with a floating chamber technique along the Norwegian coast and inside the Sogne- and Trondheimsfjord. Gas transfer velocities were related to wind speed and turbulence, but neither wind speed nor turbulence can satisfactorily predict gas transfer velocity. However, comparison to existing wind-based parameterizations showed that the data from this study have a similar trend. Generally, we measured higher transfer velocities than the parameterizations predict. In the North Atlantic, we measured transfer velocities of up to 54.9 cm h−1 versus predicted transfer velocities of 6.3 cm h−1 at a wind speed of 3.7 m s−1. In addition, we observed that measurements of transfer velocities at wind speeds below 4 m s−1 are higher than predictions. Wind-based parameterizations are lacking data in the low wind regime for validation, and we provide 25 data points for this critical wind speed range. Overall, results indicate that Norwegian fjords and the adjacent North Atlantic are sinks for atmospheric CO2 during summer, with uptake rates of −9.6 ± 7.6 μmol m−2 min−1 and −4.1 ± 1.7 μmol m−2 min−1, respectively. Due to the low partial pressure of CO2 in the upper water layer of the stratified fjords (down to 150.7 μatm), the Sogne- and Trondheimsfjord absorb 196 tons of carbon per day during the summer.
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Chamelea gallina in the coastal waters of the Anapa bay bar (the Black Sea) as a carbonate sediment producer
Oceanologia 2019, 61(4), 471-483
https://doi.org/10.1016/j.oceano.2019.04.003

Alisa R. Kosyan1,*, Boris V. Divinsky2,*
1A. N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow, Russia;
e-mail: kosalisa@yandex.ru
2P. P. Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia;
e-mail: divin@ocean.ru
*corresponding author

keywords: Population, Biomass, Shell length, Age, Rapana venosa, Black Sea.

Received 22 October 2018, Accepted 26 April 2019, Available online 16 May 2019.

Abstract

The paper presents preliminary results of monitoring the population of the bivalve Chamelea gallina, which is the main source of biogenic carbonates for the Anapa bay bar beaches (the Black Sea). It is shown that by 2017, the biomass of the clams decreased more than twice compared to 2010, but began to increase in 2018. The average sizes of C. gallina are clearly divided in terms “year” – “section” – “age”. At the same time, interannual variations of the average size are very strong in all age groups. The average shell length of C. gallina significantly increased in 2018 compared to 2016, and especially – to 2017. This may be caused by the population decline of the predator Rapana venosa feeding on clams. Geographic differences in the shell length between sections are not directly related to the distribution of biogenic elements (nitrogen and phosphorus). The differences in longevity and shell size between C. gallina from the Anapa region and distant populations from the other parts of the distribution area are likely related to its significant negative correlation with the growth rate, which in turn negatively correlates with latitude.
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Recent sea surface temperature trends and future scenarios for the Red Sea
Oceanologia 2019, 61(4), 484-504
https://doi.org/10.1016/j.oceano.2019.05.002

Mohamed Shaltout*
Faculty of Science, Department of Oceanography, University of Alexandria, Alexandria, Egypt;
e-mail: mohamed.shaltot@alexu.edu.eg
*corresponding author

keywords: Red Sea, Sea surface temperature, Chlorophyll-a, Heat exchange, Climate models, Ensemble forecast

Received 10 September 2018, Accepted 7 May 2019, Available online 24 May 2019.

Abstract

The current paper analyses the recent trends of Red Sea surface temperature (SST) using 0.25° daily gridded Optimum Interpolation Sea Surface Temperature (OISST) data from 1982 to 2016. The results of 3 different GFDL (Geophysical Fluid Dynamics Laboratory) model simulations are used to project the sea surface temperature (hereafter called Tos) under the four representative concentration pathway scenarios through 2100.

The current research indicates that the spatially annual mean (from 1982 to 2016) Red Sea surface temperature is 27.88 ± 2.14°C, with a significant warming trend of 0.029°C yr−1. The annual SST variability during the spring/autumn seasons is two times higher than during the winter/summer seasons. The Red Sea surface temperature is correlated with 13 different studied parameters, the most dominant of which are mean sea level pressure, air temperature at 2 m above sea level, cross-coast wind stress, sensible heat flux, and Indian Summer Monsoon Index.

For the Red Sea, the GFDL-CM3 simulation was found to produce the most accurate current SST among the studied simulations and was then used to project future scenarios. Analysis of GFDL-CM3 results showed that Tos in the Red Sea will experience significant warming trends with an uncertainty ranging from 0.6°C century−1 to 3.2°C century−1 according to the scenario used and the seasonal variation.

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Seasonal changes in particulate organic matter (POM) concentrations and properties measured from deep areas of the Baltic Sea
Oceanologia 2019, 61(4), 505-521
https://doi.org/10.1016/j.oceano.2019.05.004

Aleksandra Winogradow*, Anna Mackiewicz, Janusz Pempkowiak
Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland;
e-mail: aleksandra@iopan.gda.pl
*corresponding author

keywords: Suspended particulate matter, Particulate organic carbon, Particulate nitrogen, Chl a, Pheo a, δ13CPOC, Gdańsk Deep, Gotland Deep

Received 3 April 2019, Accepted 27 May 2019, Available online 13 June 2019.

Abstract

In seawater particulate organic matter (POM) serves as a food source for heterotrophic bacteria and zooplankton and is a source of dissolved organic compounds and nutrients. POM plays a critical role in transporting carbon to marine sediments where a fraction of it is buried in subsurface sediments and thus avoids conversion to carbon dioxide on shorter time scales.
Distribution and properties of POM were investigated in the Baltic Proper from 2013 to 2015. Particulate organic carbon (POC) was used to investigate POM sources and dynamics. Stable carbon isotopes (δ13C), elemental composition (C, N), chlorophyll a and POM contribution to suspended particulate matter (SPM) were also measured and interpreted. The water column exhibited concentrations ranging from 0.2 mg POC/l (deep water layer – DWL, cold season – CS) to 1.7 mg POC/l (surface water layer – SWL, warm season – WS). POM represented 0.15 to 0.45 of SPM during respective cold and warm seasons. Stable carbon isotopes (δ13CPOC) ranged from −22.5‰ (WS) to −28.0‰ (CS), while the POC/Chl a ratio ranged from 180 g/g (SWL-WS) to 300 g/g (DWL-CS). Seasonal changes were attributed to high primary production in the SWL during the WS, which represented a major POM source. Continuous mineralization/sedimentation throughout the water column constituted a major POM sink.
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Short communication



Addendum to "Stokes transport in layers in the water column based on long-term wind statistics: assessment using long-term wave statistics"
Oceanologia 2019, 61(4), 522-526
https://doi.org/10.1016/j.oceano.2019.03.003

Dag Myrhaug*, Hong Wang, Lars Erik Holmedal
Department of Marine Technology, Norwegian University of Science and Technology (NTNU), Trondheim, Norway;
e-mail: dag.myrhaug@ntnu.no
*corresponding author

keywords: Marine litter, Random surface gravity waves, Stokes transport velocity, Wave statistics, Wind statistics

Received 21 January 2019, Accepted 16 March 2019, Available online 27 April 2019.

Abstract

This article addresses the Stokes drift in layers in the water column for deep water random waves based on wave statistics in terms of the sea state wave parameters significant wave height and mean zero-crossing wave period. This is exemplified by using long-term wave statistics from the North Atlantic, and is supplementary to Myrhaug et al. (2018) presenting similar results based on long-term wind statistics from the same ocean area. Overall, it appears that the results based on long-term wave statistics and long-term wind statistics are consistent. The simple analytical tool provided here is useful for estimating the wave-induced drift in layers in the water column relevant for the assessment of the transport of, for example, marine litter in the ocean based on, for example, global wave statistics.
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Thin chlorophyll layer concomitant of the thermohaline intrusion in the confluence of the Gulf Stream and Labrador Current (a case study)
Oceanologia 2019, 61(4), 527-533
https://doi.org/10.1016/j.oceano.2019.05.001

Genrik S. Karabashev*
Laboratory of Ocean Optics, Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia;
e-mail: genkar@mail.ru
*corresponding author

keywords: Chlorophyll distribution, CDOM fluorescence, Seawater temperature, Depth-cycling fluorometer, Labrador water intrusion, Northwestern Atlantic Ocean

Received 5 January 2019, Accepted 7 May 2019, Available online 22 May 2019.

Abstract

Based on the depth-cycling data of a fluorometer probe in the northwestern Atlantic ocean, this paper considers features of the chlorophyll fluorescence layer against a background of concurrent variability of seawater temperature and fluorescence of CDOM (Colored Dissolved Organic Matter). The vertical distributions of chlorophyll fluorescence complied with the criteria of a thin chlorophyll layer at the site where changes of temperature and CDOM fluorescence were indicative of the intrusion of Labrador waters into adjacent warmer waters below the upper mixed layer. As may be supposed, the thin chlorophyll layer was due to the gyrotactic trapping of phytoplankton cells induced by water shear between the upper mixed layer and the intrusion.
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Oocyte hydration in round goby Neogobius melanostomus from the Gulf of Gdańsk: another invasive strategy?
Oceanologia 2019, 61(4), 534-539
https://doi.org/10.1016/j.oceano.2019.06.001

Hanna Kalamarz-Kubiak*, Tatiana Guellard
Department of Genetics and Marine Biotechnology, Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland;
e-mail: hkalamarz@iopan.gda.pl
*corresponding author

keywords: Oocyte hydration, Estradiol, Female round goby

Received 18 February 2019, Accepted 5 June 2019, Available online 18 June 2019.

Abstract

The round goby (Neogobius melanostomus) is one of the most abundant non-native species in the Gulf of Gdańsk that use various strategies to increase fecundity and achieve invasive success. Oocyte hydration appears to be a specific osmotic adaptation of round goby's gametes for successful fertilization and hatching. The aim of this study was to demonstrate details of oocyte final maturation and hydration during the spawning-capable phase in round goby and also compare various indices such as 17β-estradiol (E2), hepatosomatic index (HSI) and gonadosomatic index (GSI) among oocyte final maturation stages. E2 fluctuated according to the development of oocyte batches. HSI did not show significant differences throughout the oocyte maturation. GSI was an inaccurate estimator of oocyte maturation in round goby. This study, for the first time, shows that hydration does accompany oocyte final maturation in this species. These findings are important to the cognition of biology and the adaptive strategies of this invasive species to environmental factors and can be essential components of the protection and preservation of native living resources in the Gulf of Gdańsk.
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