Filip Pniewski

Morphological and molecular phylogenetic studies on Fistulifera saprophila

Accurate taxonomic identification provides the foundation for a number of diatom applications, such as the ecological monitoring of waters and the reconstruction of past environments. Despite significant recent developments in diatom taxonomy and phylogenetics, to date, only a few taxa have been studied extensively using a wide range of techniques. In this paper, data gained from intensive research on the morphology of live and cleaned diatom cells of two Fistulifera saprophila (Lange-Bertalot & Bonik) Lange-Bertalot strains isolated from the Gulf of Gdańsk are discussed. This study suggests that because specimens of F. saprophila have very delicate frustules prone to dissolution, the species has not been fully investigated and, therefore, a revised description is presented. Data on live cells and colony morphology, as well as interesting findings on the discrepancies between measurements of wet-mounted, dried and Naphrax-mounted diatom cells are also shown. The geographical distribution and ecological tolerance of F. saprophila is probably much wider than previously reported, but needs further investigation. The results of molecular phylogenetic analyses confirm the clear separation of Fistulifera Lange-Bertalot from Navicula Bory, also showing that its sister genera are Craticula Grunow, Eolimna Lange-Bertalot and Stauroneis Ehrenberg. Surprisingly, genera considered to have similar morphological characteristics, such as Mayamaea Lange-Bertalot and Sellaphora Mereschkowsky fall on a separate phylogenetic branch.

Characteristics of the growth rate and lipid production in fourteen strains of Baltic green microalgae

Abstract Screening of fourteen Baltic green algal strains provided basic data on their mass culture potential for the purpose of valuable biomass production with particular emphasis on lipid content. Selected microalgae were grown under non-stressed conditions in order to identify those characterized by efficient lipid production. The tested strains exhibited significant differences in growth patterns and lipid yields. Strains belonging to Chlorella and Stichococcus genera exhibited the highest growth rates, ranging from 0.39 d-1 to 0.50 d-1 and thus the highest final cell density (> 107 cells ml-1). Furthermore, five strains: C. minutissima BA-12, C. fusca BA-18, C. vulgaris BA-80, Monoraphidium sp. BA-165 and Chlorella sp. BA-167 were characterized by distinctively high lipid yield (> 60 mg l-1). The same strains, together with C. vulgaris BA-02, were also shown as those with the highest volumetric lipid productivity, reaching > 30 mg l-1 d-1. The tested Baltic strains performed well in terms of lipid production compared to the literature data, still leaving a great spectrum of opportunities for further lipid yield improvement.

Effect of the microphytobenthos photosynthesis on seabed backscattering properties

The development of hydroacoustic techniques for benthic habitat classification requires understanding of biological effects on seabed geoacoustic properties. The study addresses only one biological process that could potentially change the properties—photosynthesis of benthic microalgae. The previous investigations demonstrated that the impact could be important in warm southern marine waters of relatively high salinity. This motivated us to study the effect of the microphytobenthos photosynthesis on the backscattering properties of the sandy sediments of the southern Baltic Sea, an area of lower temperature and salinity. The five multiday laboratory experiments, different in hydrophysical or biological conditions, were conducted. The backscatter data were acquired in the small tank with sandy bottom under controlled constant temperature and salinity with simulated “day” and “night” conditions (light/dark (L/D) photocycles). Oxygen content in the water column as well as biological and biooptical parameters were additionally monitored. The diel variations of the backscattered signal energy were analyzed. The study demonstrated the impact of microphytobenthos photosynthesis on the backscattering properties of the marine sediment and its sensitivity to the abiotic (illumination level) and biotic (benthic microalgal biomass and macrozoobenthos bioturbation) factors.The development of hydroacoustic techniques for benthic habitat classification requires understanding of biological effects on seabed geoacoustic properties. The study addresses only one biological process that could potentially change the properties—photosynthesis of benthic microalgae. The previous investigations demonstrated that the impact could be important in warm southern marine waters of relatively high salinity. This motivated us to study the effect of the microphytobenthos photosynthesis on the backscattering properties of the sandy sediments of the southern Baltic Sea, an area of lower temperature and salinity. The five multiday laboratory experiments, different in hydrophysical or biological conditions, were conducted. The backscatter data were acquired in the small tank with sandy bottom under controlled constant temperature and salinity with simulated “day” and “night” conditions (light/dark (L/D) photocycles). Oxygen content in the water column as well as biological and biooptical parameter...