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Photosynthetic signatures of microbial colonies covering submerged hard surfaces as novel trophic status indicators : Baltic Sea studies

100%

Boniewicz-Szmyt K. , Grzegorczyk M. , Pogorzelski S. J. , Rochowski P.

Oceanologia

2023

tom Vol. 65 (1)

194--201

The study aimed to determine photosynthetic signatures, i.e. photosynthetic energy storage (ES) efficiency and photoacoustic spectra of pigment-containing biofilm communities attached to submerged solid substrates in relation to the temporal variability of the trophic state of natural water. Biofouling phenomenon signatures on artificial solid surfaces, deployed in the shallow Baltic Sea waters (Gulf of Gdańsk, Poland) for a specific period of time, were determined over a three-year period using improved photoacoustic spectroscopy apparatus based on closed cell geometry. Selected chemical parameters (oxygen, nitrogen and phosphorus concentrations) and biological productivity (primary production and Chlorophyll a; hereinafter abbreviated as Chl a) of the water body were obtained from the SatBałtyk System platform (http://satbaltyk.iopan.gda.pl) and used as comprehensive data. As a result, close cross-correlations between photosynthetic energy storage and PAS amplitude spectra and the seawater chemical parameters were demonstrated. As found, ES was negatively correlated with concentrations of biogenic elements (correlation coefficient R given in brackets): O (–0.67), P (–0.81), N (–0.76), and positively correlated with concentrations of Chl a (0.82) and primary production (0.39). As periphyton is believed to respond dynamically to water quality and environmental stresses, its photosynthetic system features can be used as novel, modern and robust indicators in marine bioassessment, in addition to traditional trophic state indices based on chemical analysis.

Detection of wavy sea surface oil-derivative contamination with forward specular high-frequency scattering

75%

Pogorzelski S. , Rochowski P. , Grzegorczyk M. , Linde B. B. J. , Skrodzka E. , Bielasiewicz Ł.

Polish Maritime Research

2020

tom nr 1

173--179

A spectrum of low-frequency (20‒30 Hz) amplitude fluctuations of the ultrasonic (10 MHz) signal specularly scattered from water surfaces covered with monomolecular and thicker crude oil origin films of well-defined, oceanographically relevant viscoelastic properties was examined in laboratory and at-sea conditions. The relationship between the Surface water wave (30 Hz) damping coefficient and the oil layer thickness was established, and compared to the one predicted by the classical Stokes theory. The depression of the spectral energy density of wind-driven waves by surface films was inferred from the ratio of acoustic signal fluctuations spectra with/without films, and compared to that resulting from the Marangoni damping theory applicable to monolayers of particular surface viscoelasticity. The agreement between the theory and experimental data was satisfactory. As shown in at-sea experiments performed with a free-floating, buoy-like acoustic system, and an artificial oil slick spread over the Baltic Sea surface, the film’s rheological Surface properties can be recovered from acoustic surface probing, as well as oil spill edge detection. Simultaneous statistical analyses of the scattered signal amplitude distribution parameters turned out to be unequivocally related to the oil substance fraction weight, oil layer thickness, and the form of oil contamination.