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Professor Andrzej Zieliński - In Memoriam Professor Andrzej Zieliński, for many years
the Scientific Director of the Institute of Oceanology, Polish Academy
of Sciences in Sopot, died on 29 April 2003 at the age of 65.
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In this issue we are publishing another
"Invited paper" in the series associated with the 50th Anniversary of
the Institute of Oceanology PAS (see the previous article: B. Woźniak,
J. Dera, D. Ficek et al., Oceanologia, 45 (2)/2003, pp. 171-245).
We also pay tribute to Professor Andrzej
Zieliński, for a great many years a member of the Editorial Board, who
died on 29th April 2003 (see p. 515).
The first four articles in the "Papers"
section (pp. 557-642) form a set describing a very significant
phenomenon in the Baltic, namely, the inflow of saline and well aerated
waters from the Danish Straits. The conditions prior to the inflow are
presented, and the inflow and its effects are described in detail. All
four papers were presented at the 3rd Baltic Sea Science Congress in
Helsinki in August 2003.
We also include 6 further articles from among those recently submitted to our journal (pp. 643-731).
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Professor Andrzej Zieliński - In Memoriam Professor Andrzej Zieliński, for many years
the Scientific Director of the Institute of Oceanology, Polish Academy
of Sciences in Sopot, died on 29 April 2003 at the age of 65.
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The fine structure of marine
hydrophysical fields and its influence on the behaviour of plankton: an
overview of some experimental and theoretical investigations:
Oceanologia 2003, no 45(4), pp. 517-555
Czesław Druet
Institute of Oceanology, Polish Academy of Sciences, Powstańców Warszawy 55, PL-81-712 Sopot, Poland;
e-mail: druet@iopan.gda.pl
Keywords: Small-scale stratification, intermitent stratification, fine structure, turbulence, turbulent mixing, turbulent diffusion, phytoplankton, zooplankton
Manuscript received 31 July 2003, reviewed 17 November 2003, accepted 20 November 2003.
This article is an overview which presents in brief some of the results of research done in the last 20 years on the structure and dynamics of intermittent fine structure in the euphotic zone of the sea and its effect on the behaviour of marine plankton. The introduction provides a general characterisation of this structure and its relations with the plankton concentration field. Chapter 2 covers turbulent mixing processes in layers of homogeneous fine structure, and discusses the dynamic interactions of these layers and how these affect the behaviour of marine phyto- and zooplankton. The principal conclusions, in brief, are that the current state of knowledge, not only of intermittent fine structure itself and its dynamic transformations, but also of the influence of these processes on the behaviour of marine plankton, is today still a long way from permitting an accurate description of reality. Moreover, both empirical investigations (in situ and in the laboratory) and mathematical modelling, despite the quite advanced stage that the latter has reached, need to be continued. For this reason the prime aim of this article is to show up the gaps in our knowledge which future research in this complex, interdisciplinary area of oceanography should attempt to fill.
Hydrographic and hydrochemical conditions in the Gotland
Deep area between 1992 and 2003
Oceanologia 2003, no 45(4), pp. 557-569
Günther Nausch, Wolfgang Matthäus, Rainer Feistel
Baltic Sea Research Institute
Seestrasse 15, D-18119 Rostock-Warnemünde, Germany;
e-mail: guenther.nausch@io-warnemuende.de
Keywords: Stagnation periods, deep water renewal, hydrography, nutrient distribution, nutrient pools
Manuscript received 29 September 2003, reviewed 20 October 2003, accepted 12 November 2003.
This paper was presented at the Baltic Sea Science Congress (BSSC) in August 2003 in Helsinki.
In memory of Stig H. Fonselius (1921-2003), who studied the basic hydrographic-hydrochemical conditions in the Gotland Deep area during the 1960s.
The paper describes the hydrographic-hydrochemical development in the
eastern Gotland Basin between the major saltwater inflows into the
Baltic Sea in 1993 and 2003. This period is characterised by only low
inflow activity. The most important hydrographic events were the
effects of the very strong inflow in 1993 and the weak inflows in
1993/1994 and 1997. The 1993/1994 inflows led to deep-water renewal, a
steep fall in deep-water temperatures, and increasing salinity. The
effects of the inflow of very warm, saline and oxygen-rich water in
autumn 1997 were observed in the deep water in 1998, resulting in
temperatures rising to 7°C. The recent renewal in spring 2003 is
reflected in the decreasing temperature, higher salinity and improved
ventilation of the bottom water.
Changes in the redox conditions exert a
considerable influence on the nutrient distribution. During stagnation
periods, there is enrichment of phosphate and ammonium, while nitrate
is absent. Thus, around 31 µmol l-1 ammonium and 7 µmol l-1
phosphate were measured prior to the water renewal in 2003. Deep-water
ventilation results in lower phosphate concentrations of around 2 µmol l-1, the nitrification of ammonium and the occurrence of nitrate.
For the observation period, an estimate of
nutrients stored in the deep water was done for the eastern Gotland
Basin. During the recent stagnation period, there was an increase of up
to 150% in the phosphate pool below the halocline, whereas the pool of
inorganic nitrogen compounds decreased to 80% compared with 1992 when
the previous stagnation period had ended. Under specific circumstances,
these unbalanced nutrients can be made available to the upper water
layers and can induce large-scale blooms of algae, especially of
cyanobacteria.
Warm waters of summer 2002 in the deep Baltic Proper
Oceanologia 2003, no 45(4), pp. 571-592
Rainer Feistel1,*,
Günther Nausch1,
Volker Morholz1,
Elżbieta Łysiak-Pastuszak2,
Torsten Seifert1,
Wolfgang Matthäus1,
Siegfried Krüger1,
Ian Sehested Hansen3
1Baltic Sea Research Institute,
Seestrasse 15, D-18119 Rostock-Warnemünde, Germany;
e-mail: rainer.feistel@io-warnemuende.de
2Institute of Meteorology and Water Management, Marine Branch,
al. Waszyngtona 42, PL-81-342, Gdynia, Poland
3DHI Water & Environment, Agern Allé 5, DK-970 Hørsholm, Denmark
*corresponding author
Keywords: Inflow, hydrography, warm water, temperature, oxygen conditions, Baltic Sea
Manuscript received 29 September 2003, reviewed 5 November 2003, accepted 17 November 2003.
This paper was presented at the Baltic Sea Science Congress (BSSC) in August 2003 in Helsinki.
From October 2002 until March 2003 surprisingly warm, oxygenated waters were frequently encountered in the Baltic Sea in the area between the Bornholm and Fårö Deeps from the halocline down to the bottom. Owing to their ventilation effect in the stagnating deep waters, their occasional observations have partly been incorrectly attributed to the inflow events of October 2002 or January 2003. The emergence of some of these waters can be traced back to the exceptional summer weather conditions in August and September 2002 in central Europe. The warm waters played a remarkable renewal pacemaker role for the subsequent important winter inflow of January 2003. The evolution of this summer inflow is described and possible causes are discussed.
Inflow waters in the deep regions of the southern Baltic Sea - transport and transformations
Oceanologia 2003, no 45(4), pp. 593-621
Jan Piechura, Agnieszka Beszczynska-Möller
Institute of Oceanology, Polish Academy of Sciences, Powstańców Warszawy 55, PL-81-712 Sopot, Poland;
e-mail: piechura@iopan.gda.pl
Keywords: Baltic Sea, inflow water, transport, mixing
Manuscript received 29 September 2003, reviewed 17 October 2003, accepted 20 October 2003.
This paper was presented at the Baltic Sea Science Congress (BSSC) in August 2003 in Helsinki.
A medium-sized inflow (about 200 km3 according to IOW data, - personal communication) of saline water into the southern Baltic Sea occurred during January 2003. Unlike any previously observed inflow, this one brought very cold water, of temperatures around 1-2°C and less. Since the temperature of the deep water in the southern Baltic before the inflow was exceptionally high (11-12°C), the inflowing waters produced dramatic changes and a steep temperature gradient. The movement of the inflowing waters through the deep basins and channels of the Baltic Sea from the Arkona Basin to the Gdansk Deep during next 4-8 months is described. Frequent mesoscale structures and intensive mixing followed the eastward transport of the inflow water, particularly in the Bornholm Deep and Słupsk Furrow. The present paper is based on data collected during of 6 cruises r/v "Oceania" between December 2002 and August 2003. The last cruise in August took place in order to assess the long-term consequences of the inflow.
Temporal and spatial evolution of the Baltic deep water renewal in spring 2003
Oceanologia 2003, no 45(4), pp. 623-642
Rainer Feistel, Günther Nausch, Wolfgang Matthäus, Eberhard Hagen
Baltic Sea Research Institute,
Seestrasse 15, D-18119 Rostock-Warnemünde, Germany;
e-mail: rainer.feistel@io-warnemuende.de
Keywords: Inflow, deep water renewal, oxygen conditions, Baltic Sea
Manuscript received 29 September 2003, reviewed 5 November 2003, accepted 12 November 2003.
This paper was presented at the Baltic Sea Science Congress (BSSC) in August 2003 in Helsinki.
In January 2003, a deep-water renewal process in the Baltic Sea commenced with an inflow of about 200 km3 of cold and well oxygenated water from the Kattegat, half of which was of salinity >17 PSU; it is considered to be the most important inflow since 1993. Related front propagation and the ventilation of anoxic waters between the western and the central Baltic were recorded by the Darss Sill measuring mast, the Arkona Basin buoy, a subsurface mooring in the Eastern Gotland Basin, and hydrographic research cruises conducted in January, February, March, May and August 2003. Already in May, the central Gotland Basin was reached by water with near-bottom oxygen concentrations among the highest ever recorded there. A comprehensive review of the observed spatial and temporal structures together with additional background data is presented. Estimates of the intensity of the present inflow are discussed.
Variations in the physical properties of surf generated aerosols with altitude
Oceanologia 2003, no 45(4), pp. 643-653
Tymon Zieliński
Institute of Oceanology, Polish Academy of Sciences, Powstańców Warszawy 55, PL-81-712 Sopot, Poland;
e-mail: tymon@iopan.gda.pl;
Keywords: Surf zone, marine aerosol, vertical profile, concentration gradient
Manuscript received 28 August 2003, reviewed 22 October 2003, accepted 30 October 2003.
Vertical profiles of marine aerosol size distribution and concentration in the marine boundary layer over surf zones depend strongly on wind speed, direction and duration as well as the sea bottom profile. The measurements in the present study were carried out in various seasons of the year with all these factors being taken into consideration. The data with respect to offshore winds were neglected in the calculations, since in such cases the major aerosol contribution was from terrigenous and anthropogenic particles. It was confirmed that in the range of wind speeds from 1 m s-1 to 12 m s-1 there were measurable differences in the concentrations, particularly in the size distribution of marine aerosol particles at two stations differing with respect to their sea bottom profiles.
SeaWiFS-derived products in the Baltic Sea: performance analysis of a simple atmospheric correction algorithm
Oceanologia 2003, no 45(4), pp. 655-677
Barbara Bulgarelli, Frédéric Mélin, Giuseppe Zibordi
Joint Research Centre of the European Commission,
Institute for Environment and Sustainability,
Inland and Marine Waters Unit,
TP272; IT-21020 Ispra (VA), Italy;
e-mail: barbara.bulgarelli@jrc.it
Keywords: Baltic Sea, remote sensing, SeaWiFS, atmospheric correction, ocean colour, radiative transfer
Manuscript received 28 August 2003, reviewed 13 October 2003, accepted 29 October 2003.
The accuracy analysis of an approximate atmospheric correction algorithm for the processing of SeaWiFS data has been investigated for the Baltic Sea. The analysis made use of theoretical radiances produced with the FEM radiative transfer code for representative atmosphere-water test cases. The study showed uncertainties in the determination of the aerosol optical thickness at 865 nm and of the Ångström exponent lower than ± 5% and ± 10%, respectively. These results were confirmed by the analysis of 59 match-ups between satellite-derived and in situ measurements for a site located in the central Baltic. Because of the relatively high yellow substance absorption, often combined with the slanted solar illumination, the retrieval of the water-leaving radiance in the blue part of the spectrum appeared to be highly degraded, to the extent that almost no correlation was found between retrieved and simulated values. Better results were obtained at the other wavelengths. The accuracy in the estimation of the remote sensing reflectance ratio R35 decreased with diminishing chlorophyll a concentration and increasing yellow substance absorption, ranging between ± 7% and ± 47%. The propagation of R35 uncertainties on chlorophyll a estimation was quantified. Keeping the same atmosphere-water conditions, the atmospheric correction scheme appeared sensitive to seasonal changes in the Sun zenith.
Is iron a limiting factor of Nodularia spumigena blooms?
Oceanologia 2003, no 45(4), pp. 679-692
Lidia Paczuska, Alicja Kosakowska
Institute of Oceanology, Polish Academy of Sciences,
Powstańców Warszawy 55, PL-81-712 Sopot, Poland;
e-mail: lipa@iopan.gda.pl
Keywords: Nodularia spumigena, iron, growth, bloom, Baltic Sea
Manuscript received 12 September 2003, reviewed 24 October 2003, accepted 27 October 2003.
The study was carried out as part of the statutory activities of the Institute of Oceanology PAS (grant No. II.3/2003) and was supported by the Polish State Committee for Scientific Research (grant No. 3 PO4F 059 23).
It is well known that a deficiency of iron, a trace element
essential to every living organism, limits the growth of algae
and cyanobacteria. Nodularia spumigena Mertens is a blue-green
algae species inhabiting the Baltic region that often forms toxic
blooms.
The aim of the study was to assess the growth of the toxic cyanobacteria
with respect to iron bioavailability. The measured growth parameters
were the numbers of cells (optical density), chlorophyll a
and pheopigment a concentrations. The iron concentrations
used ranged from 10-7 to 10-4 mol dm-3. Under iron stress
conditions (<5 × 10-7 mol dm-3), growth inhibition, gradual
pigment decay and cell mortality were observed. However, enriching
the medium with complexing factors like citric acid and EDTA
significantly stimulated the growth rate and chlorophyll a
production. The citric acid - EDTA - Fe (5 × 10-7 mol dm-3)
complex was demonstrably effective in stimulating the rate of
cell division. Starting with 10-6 mol dm-3, the higher the
iron(III) concentration used in the media, the more intensive
the growth of the cyanobacteria populations. This was most rapid
in the presence of high iron concentrations (10-4 mol dm-3),
regardless of the presence of complexing agents.
It appears that the growth of toxic cyanobacteria N. spumigena,
and thus also its ability to form blooms, may well
depend on iron availability in the environment.
Preliminary results on low molecular weight organic substances dissolved in the waters of the Gulf of Gdańsk
Oceanologia 2003, no 45(4), pp. 693-704
Waldemar Grzybowski1,*, Janusz Pempkowiak2
1Institute of Oceanography, University of Gdańsk,
al. Marszałka Piłsudskiego 46, PL-81-378 Gdynia, Poland;
e-mail: grzyb@panda.bg.univ.gda.pl
2Institute of Oceanology, Polish Academy of Sciences,
Powstańców Warszawy 55, PL-81-712 Sopot, Poland
*corresponding author
Keywords: Dissolved organic carbon, low molecular weight fraction, ultrafiltration, absorbance
Manuscript received 5 August 2003, reviewed 22 September 2003, accepted 7 October 2003.
The content of low molecular weight LMW (<1000 Da) dissolved organic substances was determined by ultrafiltration (concentration factor of 2) in different water samples collected in the Gulf of Gdańsk. The proportion of this fraction (based on organic carbon concentration) ranged from 24 to 57%. The lowest percentage was detected in riverine samples. The DOC concentrations in ultrafiltrates was similar in all the samples analysed. The absorbance proportion (at 250 nm) due to the low molecular fraction in the overall absorbance ranged from 14 to 45% and in all but one sample was lower than the DOC percentage. There was no relationship between DOC and absorbance in the LMW fractions (r2 = 0.08), in contrast to the characteristics of the "bulk" samples (r2 = 0.88).
Microphytobenthic primary production along a non-tidal sandy beach gradient: an annual study from the Baltic Sea
Oceanologia 2003, no 45(4), pp. 705-720
Barbara Urban-Malinga1, Jozef Wiktor2
1Centre for Ecological Research, Polish Academy of Sciences, Dziekanów Leśny,
Konopnickiej 1, PL-05-092 Łomianki, Poland;
e-mail: basiam@iopan.gda.pl
2Institute of Oceanology, Polish Academy of Sciences,
Powstańców Warszawy 55, PL-81-712 Sopot, Poland
Keywords: Microphytobenthos, primary production, sandy beach, chlorophyll a, Baltic Sea
Manuscript received 18 July 2003, reviewed 3 September 2003, accepted 11 September 2003.
The microphytobenthic primary production and chlorophyll a content were studied over the annual cycle (May 1998 - May 1999) on a non-tidal Baltic sandy beach at three stations along the beach gradient: littoral, waterline and splash zone. The chlorophyll a concentrations varied between 0.88 and 12.18 µg cm-3. Net and gross primary production rates respectively lay within the ranges 0.1-31.4 mgC m-2 h-1 and 0.2-41.8 mgC m-2 h-1. The highest values of both Chl a content and primary production were noted at the littoral station, the lowest ones at the waterline. The mean annual P/B ratio was highest at the waterline. The differences in Chl a content between stations were statistically significant and may be related to water dynamics, resuspension and water content. Production rates were highly variable on monthly time scales, and the highest results at all the study locations were noted in July. The gross photosynthetic rates were significantly correlated with water temperature.
Alexandrium minutum cysts in sediment cores from the Eastern Harbour of Alexandria, Egypt
Oceanologia 2003, no 45(4), pp. 721-731
Amany A. Ismael, Ahmed M. Khadr
Oceanography Department,
Faculty of Science, Alexandria University, EG-21511 Alexandria, Egypt;
e-mail: amany_3@yahoo.com
Keywords: Alexandrium minutum, cysts, sediment cores, Eastern Harbour
Manuscript received 16 July 2003, reviewed 9 October 2003, accepted 27 October 2003.
Alexandrium minutum cysts were studied in sediment cores from its type locality, the Eastern Harbour of Alexandria, following the disappearance of the species from the plankton since 1994. Three cores were sampled in the summer of 1999 along the north-south axis of the harbour. The sediments were subjected to grain size analysis and their organic carbon content was determined. The sediments consisted of medium, coarse and very coarse sand. Grain size and organic carbon content were negatively and significantly correlated in core 1 but followed a parallel trend in cores 2 and 3. Seven dinoflagellate cysts, representing 6 genera were identified from the cores. Their relative abundance showed a remarkable difference. A. minutum cysts contributed a maximum of 17.4% to the total cysts. The distribution profile of A. minutum cysts in the cores reflects the bloom duration but not its productivity. The cyst distribution in the cores is the resultant of two opposite processes, the sedimentation rate and the continuous erosion of the bottom sediments, which is not related to sediment texture.