Oceanologia No. 38 (3) / 96

Papers

Anna Rozwadowska
Institute of Oceanology, Polish Academy of Sciences, Sopot

Influence of clouds on the broadband spectral irradiance at the Baltic surface
Oceanologia 1996, no. 38 (3), pp. 297–315

Keywords: Baltic atmosphere; Broadband spectral irradiance; Clouds Manuscript received May 14, 1996, in final form June 21, 1996.

Abstract

On the basis of downward irradiance data in the ultraviolet, visible and infrared spectral intervals as well as of meteorological observations collected during several cruises to the Baltic, the influence of clouds and solar zenith angle on the broadband spectral composition of solar radiation reaching the Baltic surface is analysed. The relation between the atmospheric transmittance of total irradiance and solar zenith angle, and the ratios of broadband spectral irradiance to the total for both visible and infrared radiation have been estimated by polynomials.

Slawomir B. Wozniak
Institute of Oceanology, Polish Academy of Sciences, Sopot

Sea surface slope distribution and foam coverage as functions of the mean height of wind waves
Oceanologia 1996, no. 38 (3), pp. 317–332

Keywords: Wind waves; Slope distribution; Foam coverage; Mean wave height; Modified Cox-Munk expression; Modified Gordon-Jacobs expression Manuscript received April 9, 1996, in final form May 29, 1996.

Abstract

The article discusses problems of the statistical description of a wind-ruffled sea surface for optical modelling purposes. A new parameter, namely the mean height of the waves

, is used in both the slope distribution of the ruffled sea surface and the foam coverage of the surface. Unlike the parameter used up to the present, i.e. the wind speed over the sea surface v, the mean height of the waves

is connected with a large number of hydrometeorological and geometrical factors modifying the state of wave motion of the sea (e.g. the wind fetch D, the sea depth h, the shape of the coastal region etc.). A theoretical basis for applying this new parameter and modifying dependences for the slope distribution and the foam coverage of the ruffled sea surface is given. In addition this paper contains an initial verification of the ideas presented with the small number of data available in the literature.

Jadwiga Mrozek-Lejman, Grazyna Karbowniczek-Gratkowska
Marine Physics Department, University of Szczecin, Szczecin

The position of the seasonal thermocline in southern Baltic waters polluted with crude oil
Oceanologia 1996, no. 38 (3), pp. 333–349

Keywords: Seasonal thermocline; Eutrophic seawater; Crude oil pollution Manuscript received March 5, 1996, in final form June 7, 1996.

Abstract

The paper deals with the formation of the thermocline and the mixed layer in a sea polluted with crude oil when the natural optical parameters of eutrophic seawater are seasonally variable. Differentiation of the degree of eutrophication of the seawater is expressed in terms of the concentrations of chlorophyll and yellow substances. The occurrence of crude oil pollution is taken into account by modifying the time-variable absorption coefficient of the seawater – crude oil system. The variability in the absorption spectra of natural seawater in the spring – summer season is estimated on the basis of investigations of seasonal changes in the chlorophyll concentration in the southern Baltic.

Numerical simulations were carried out for Baltic and Gulffax crude oil using the one-dimensional integral DKTz–2 model. The computations were performed for monthly average values of parameters determining the state of the southern Baltic environment collected over several years. Experimentally found crude-oil optical parameters (light refraction and absorption coefficients) were applied, as were the variability with time of these parameters and that of the crude oil layer thickness.

The results of the numerical simulations show that the increase in the volumetric concentration of crude oil in the upper sea layer causes the thermocline to be formed closer to the water surface. Simultaneously, the thickness of the mixed layer decreases but its temperature rises. If a crude oil layer appears on the water surface, the trend of the changes is the same.

Amany Mohamed Haroon
Academy of Scientific Research and Technology, National Institute of Oceanography and Fisheries, Cairo

Anna Szaniawska
Institute of Oceanography, Gdansk University, Gdynia

Comparative estimations of the energy content of Enteromorpha spp. using different methods
Oceanologia 1996, no. 38 (3), pp. 351–360

Keywords: Enteromorpha spp.; Comparative determination; Energy content; Jurata Manuscript received March 4, 1996, in final form May 28, 1996.

Abstract

The energy content of Enteromorpha spp. from Jurata (situated in the western part of the Gulf of Gdansk) was determined. The values were measured directly by combustion in a microbomb calorimeter and indirectly by calculation based on the biochemical composition, and on carbon and nitrogen contents.

On the basis of the results obtained, very little difference – on average 2.98 5.69% (0.54 0.67 J mg^-1 of DW) – was found between the energy values calculated from the carbon content and those calculated from carbon and nitrogen contents. Moreover, the values calculated from both these sources were higher those that calculated from the biochemical composition by about 14.95 12.24% (2.09 1.72 J mg^-1 of DW) and 17.28 14.41% (2.63 2.07 J mg^-1 of DW) for the two methods respectively. At the same time, large differences were found between the values calculated using microbomb calorimetry and other methods (biochemical composition, carbon content, and carbon and nitrogen contents): they were 20.40 15.09%, 33.76 5.86% and 35.74 6.71% for the three methods respectively.

Ashraful Mohammed Haque
Institute of Oceanology, Polish Academy of Sciences, Sopot

Maria Szymelfenig
Institute of Oceanography, Gdansk University, Gdynia

Jan Marcin Weslawski
Institute of Oceanology, Polish Academy of Sciences, Sopot

The sandy littoral zoobenthos of the Polish Baltic coast
Oceanologia 1996, no. 38 (3), pp. 361–378

Keywords: Baltic littoral; Benthos Manuscript received January 26, 1996, in final form May 20, 1996.

Abstract

Macrobenthos and meiobenthos were quantitatively sampled in the sandy littoral along the Polish Baltic Sea coast in August 1994. Macrofaunal abundance (0–987 indiv. m^-2), biomass (0–3.19 g m^-2 wet wt.) and the number of species (3) were very low. Eight meiofaunal animal groups were found. Meiofaunal abundance (38–760 indiv. 10^-1 cm^-2) was dominated by Nematoda and Turbellaria, the biomass (0.86–34.9 mg 10^-1 cm^-2 wet wt.) by Oligochaeta. In terms of biomass, the macrobenthos:meiobenthos ratio ranged from 0.02 to 5.17. Macrofaunal abundance and biomass were more variable than those of the meiofauna.

Maria Wlodarska-Kowalczuk
Institute of Oceanology, Polish Academy of Sciences, Sopot

Urszula Janas, Anna Szaniawska
Institute of Oceanography, Gdansk University, Gdynia

Hydrogen sulphide and other factors influencing the macrobenthic community structure in the Gulf of Gdansk
Oceanologia 1996, no. 38 (3), pp. 379–394

Keywords: Gulf of Gdansk; Macrofaunal communities; Hydrogen sulphide; Biodiversity Manuscript received May 8, 1996, in final form July 24, 1996.

Abstract

Three stations in the Gulf of Gdansk were sampled monthly for one year with regard to macrozoobenthos composition, oxygen content and temperature of near-bottom waters, granulometry, organic matter content and H₂S concentration in sediments. The differences in H₂S concentrations at the stations were most conspicious. The presence and concentrations of H₂S appeared to be the decisive factor for the grouping of samples in the Bray-Curtis Similarity Index-based ordination. Even seasonality was of secondary importance. The number of species and the Shannon Indices decreased, and the dominance of the predominant species – Macoma balthica – increased in accordance with the H₂S gradient between the stations. The community was dominated by detritus-feeders.

Communications

Waldemar Grzybowski
Institute of Oceanography, Gdansk University, Gdynia

Preliminary results of dissolved organic carbon concentration measurements in the Vistula river mouth using high-temperature catalytic oxidation
Oceanologia 1996, no. 38 (3), pp. 395–403

Keywords: Salinity; Dissolved organic carbon; High-temperature catalytic oxidation; Gulf of Gdansk

Abstract

Some 100 measurements of dissolved organic carbon (DOC) concentrations were made in the water in the Vistula river mouth area using high-temperature catalytic oxidation. The results ranged from 4.8 to 22.4 mg dm^-3. No relationship was detected between DOC and salinity within the 0.9–7.6 PSU salinity range.

Anna Wasik, Ewa Mikolajczyk
Department of Cell Biology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw

The seasonal succession of hyaline Helicostomella subulata and agglutinated Tintinnopsis lobiancoi – dominants of the Baltic Tintinnina (Ciliophora)
Oceanologia 1996, no. 38 (3), pp. 405–418

Keywords: Baltic Sea; Helicostomella subulata; Tintinnids; Tintinnopsis lobiancoi

Abstract

Tintinnid species composition and abundance were determined in surface water samples taken from four sites in the Gulf of Gdansk, and along four cruise tracks from the Gulf of Gdansk to Helsinki. The seasonal succession of two dominants – the hyaline Helicostomella subulata and the agglutinated Tintinnopsis lobiancoi – was evident. The former coincided with the beginning of summer and was replaced early in the season by the latter. Other Tintinnina species were found only occasionally and did not significantly affect the total tintinnid abundance.