Oceanologia No. 37 (2) / 95

Papers

Olga J. Koblentz-Mishke
Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow

Bogdan Wozniak, Slawomir Kaczmarek
Institute of Oceanology, Polish Academy of Sciences, Sopot

B. V. Konovalov
Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow

The assimilation of light energy by marine phytoplankton. Part 1. The light absorption capacity of the Baltic and Black Sea phytoplankton (methods; relation to chlorophyll concentration)
Oceanologia 1995, no. 37 (2), pp. 145–170

Keywords: Marine photosynthesis; Specific absorption of phytoplankton pigments; Baltic Sea; Black Sea

Manuscript received January 24, 1995, in final form May 30, 1995.

Abstract

This paper discusses the significance of the light absorption capacity of marine phytoplankton as a measure of the photosynthetically active phytoplankton biomass, and as a means of calculating the energy flux at the input of the production process; its neccesity in evaluating the efficiency of phytoplankton photosynthesis and working out models of primary production in the sea is stressed.

The methods worked out by the authors of this paper and by other specialists are reviewed, and the values of light absorption by phytoplankton obtained during five cooperative cruises to the Baltic and Black Seas are compared with data published by other authors. These values demonstrate good agreement with the results of modelling light absorption by phytoplankton inhabiting waters of different productivity.

Amany Mohamed Haroon
Academy of Scientific Research and Technology, National Institute of Oceanography and Fisheries, 101 Kaser El-eni St., Cairo, Egypt

Anna Szaniawska
Institute of Oceanography, Gdansk University, Gdynia

Variations in energy values and lipid content in Enteromorpha spp. from the Gulf of Gdansk
Oceanologia 1995, no. 37 (2), pp. 171–180

Keywords: Energy values; Lipid content; Enteromorpha spp.; Gulf of Gdansk

Manuscript received April 3, 1995, in final form June 6, 1995.

Abstract

The variations in energy values and lipid content in Enteromorpha spp. collected from Jurata at monthly intervals during the period from November 1992 to October 1993 and from 7 stations situated on the coast of the Gulf of Gdansk during September 1993 in relation to season and place are presented.

As far as the samples from Jurata are concerned, seasonal variations in energy values and lipid content are observed when the highest total energy values and lipid content were recorded at the beginning of the growing season during April and May – between 14.0 and 10.8 J mg^-1 DW – for total energy and between 6.0 and 5.0% of DW for lipid content. After this time, these values started to decrease and fluctuated between 8.2 and 10.5 J mg^-1 DW for total energy and between 2.5 and 3.7% of DW for lipid content. The values of ash fluctuated within a wide range between 12.2 and 27.5% of DW; here, the highest values were recorded at the end of the growing season and the lowest values at its beginning.

Moreover different values were recorded for energy, organic matter, ash and lipid content in samples collected from different stations on the coast of the Gulf of Gdansk during September, where the highest total energy values and lipid content were recorded in the samples from Chalpy followed by those from Jurata – 9.9 and 9.5 J mg^-1 DW for total energy and 3.4 and 3.5% of DW for lipid content respectively.

Marianna Pastuszak
Department of Oceanography, Sea Fisheries Institute, Gdynia

The hydrochemical and biological impact of the river Vistula on the pelagic system of the Gulf of Gdansk in 1994. Part 1. Variability in nutrient concentrations
Oceanologia 1995, no. 37 (2), pp. 181–205

Keywords: Baltic Sea; Nutrients; Vistula impact; Seasonal/spatial variability

Manuscript received April 18, 1995, in final form July 11, 1995.

Abstract

The paper discusses the physical and biological factors as well as the water/nutrient discharges by the river Vistula affecting nutrient distribution in the Gulf of Gdansk in 1994. Seasonal and spatial variability in nutrient distribution is discussed with reference to the biological cycle in the coastal marine ecosystem and with respect to seasonal variability in water/nutrient discharges by the river. The greatest discharge of nutrients, with extremely high concentrations of nitrates, was recorded in April 1994. Powerful water dynamics, mainly wind-induced, are depicted as a factor responsible for the transport/transformation of riverine water. Separate mini-ecosystems, characterised by distinguishable chemical, physical and biological parameters, were found. High concentrations of ammonia in July may have been related to its regeneration by abundant zooplankton. Low silicate concentrations in November may have resulted from a diatom bloom.

Stanislaw Ochocki, Jan Nakonieczny, Henryk Chmielowski, Mariusz Zalewski
Department of Oceanography, Sea Fisheries Institute, Gdynia

The hydrochemical and biological impact of the river Vistula on the pelagic system of the Gulf of Gdansk in 1994. Part 2. Primary production and chlorophyll a
Oceanologia 1995, no. 37 (2), pp. 207–226

Keywords: Baltic Sea; Primary production; Seasonal/spatial variability

Manuscript received April 18, 1995, in final form August 2, 1995.

Abstract

The time and space variability in potential and in situ primary production values, and in chlorophyll a concentrations in the Gulf of Gdansk in 1994 are presented and discussed. The spatial variability in the distribution of these parameters is closely related to both the powerful dynamics of the water masses in this region and the river Vistula discharges. The eutrophicating impact of the Vistula is particularly evident in the narrow inshore zone, to the east and west of the river mouth. Seasonal variability in primary production and chlorophyll a concentrations was recorded; their particularly high values in April 1994 were due to the plankton bloom. The assimilation numbers, characterising the intensity of phytoplankton photosynthesis, varied within the 1.6–5.5 mgC mgchl^-1 h^-1 range.

Eugeniusz Kozaczka, Grazyna Grelowska, Paulina Bittner
Naval Academy, Gdynia

Alfred Grelowski
Department of Oceanography, Sea Fisheries Institute, Gdynia

The influence of Vistula water on the thermodynamic and acoustic parameters of the Gulf of Gdansk
Oceanologia 1995, no. 37 (2), pp. 227–248

Keywords: Conditions for acoustic wave propagation in the Baltic Sea; Acoustic and thermodynamic parameters of seawater; Low-salinity seawater Manuscript received April 27, 1995, in final form July 31, 1995.

Abstract

The article discusses the results of investigations into the influence of water from the river Vistula on the thermodynamic and acoustic conditions in the Gulf of Gdansk. On the basis of monthly temperature and salinity distributions averaged over 15 years, the annual variation in selected thermodynamic and acoustic parameters was determined at station ZN2 off the Vistula mouth and at station P110 in the central part of the Gulf.

In order to find the best way of calculating the area influenced by Vistula water, the spatial distributions of density, compressibility, expansion, specific heat, speed of sound and the nonlinearity parameter B/A were determined. Depending on the meteorological and hydrological conditions in a given year, the spread of Vistula water is reflected by the distributions of several parameters. Analysing a number of parameters together seems to be the most suitable way of estimating this spread. The present analysis also allows the origin of the Gulf waters to be studied. These investigations can be used to forecast conditions for the propagation of finite-amplitude acoustic waves in the area where Vistula water interacts with the seawater in the Gulf of Gdansk.

Lucyna Falkowska, Adam Latala
Institute of Oceanography, Gdansk University, Gdynia

Short-term variations in the concentrations of suspended particles, chlorophyll a and nutrients in the surface seawater layers of the Gdansk Deep
Oceanologia 1995, no. 37 (2), pp. 249–284

Keywords: Particles; Chlorophyll a; Nutrients; Microlayer; Gdansk Deep Manuscript received April 24, 1995, in final form September 13, 1995.

Abstract

An important interface between the atmosphere and sea, the sea-surface microlayer is a collection phase for many natural and anthropogenic materials, serving both as a source and a recipient of materials from the atmosphere and the water column.

Samples of sea-surface microlayer and subsurface bulk water were collected at short time intervals (every 1 h and every 4 h) in two periods: 2–6.06.1992 and 30.04–4.05.1994 and analysed for particle concentration with a Multisizer II Coulter Counter.

The results present diurnal variations in particle numbers and their distribution functions. The data illustrate the effect of the chlorophyll a and nutrient contents on particle concentration.

Both particle concentration and chlorophyll a content underwent periodic fluctuations. Maximum values were recorded in the morning and afternoon hours.

Communications

Slawomir Kaczmarek, Bogdan Wozniak
Institute of Oceanology, Polish Academy of Sciences, Sopot

The application of the optical classification of waters in the Baltic Sea (Case 2 Waters)
Oceanologia 1995, no. 37 (2), pp. 285–297

Keywords: Bio-optical classification of natural waters; Diffuse attenuation coefficient for irradiance; Baltic Sea

Abstract

In this study, the spectral values of the diffuse attenuation coefficients for downwelling irradiance K_d( lambda

), which were measured in the visible spectrum in the Baltic Sea, are compared with similar spectra obtained theoretically on the basis of the classification of the optical properties of Case 1 Waters developed by Wozniak. The analysis of 481 pairs of spectra K_d ( lambda

) shows that in order to use this classification for a description of Baltic waters, it is necessary to introduce into it a new component

) [m^-1], which may be approximated by

K( lambda ) = 0.0716 e ^-0.0117 ⁽ ^{– 550)},

where lambda [nm] is the wavelength.

The form of the equation approximating the K( lambda ) spectrum and the value of the exponential factor suggest that the term K( lambda ) is related to a high concentration of allogenic yellow substance in the Baltic Sea.

Jerzy Olszewski, Jolanta Kusmierczyk-Michulec, Maciej Sokolski
Institute of Oceanology, Polish Academy of Sciences, Sopot

A method for the continuous measurement of the diffusivity of the natural light field over the sea
Oceanologia 1995, no. 37 (2), pp. 299–310

Keywords: Atmospheric optics; Light field diffusivity; Method of measurement Manuscript received April 27, 1995, in final form August 31, 1995.

Abstract

This paper discusses a method of measuring the diffusivity of the atmospheric natural light field continuously and automatically even on board a ship in motion. The idea of this method is to remove cyclicly from the photodetector's field of view successive parts of the horizon (one of them including all direct solar radiation), and is implemented by means of a strip diaphragm with fixed dimensions, rotating automatically around the optical axis of a cosine collector.

The usefulness of the strip method was justified on the basis of a comparison with the disc method (the Sun covered by a disc) and comparative error analysis.