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1

Impact of the Słupia River waters on microbial communities in the port of Ustka and adjacent Baltic Sea waters

Rychert K., Wielgat-Rychert M., Lemańczyk Ł.

Oceanological and Hydrobiological Studies

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2018

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Vol. 47, No. 4

429--438

EN

The distribution of bacterial and ciliate abundance, ciliate community composition and other parameters were studied during summer along a transect from the mouth of the Słupia River to offshore waters (southern Baltic Sea). Bacteria were examined under an epifluorescence microscope and ciliates were observed under an inverted microscope. Two water masses were identified along the transect. Less saline waters in the river mouth and in the surface layer in the port of Ustka were characterized by high bacterial abundance (5.51–6.16 × 106 ml-1) and low ciliate abundance (0.34–0.90 cells ml-1). More saline waters in the near-bottom zone in the port of Ustka and in the surface layer outside the port contained smaller numbers of bacteria (0.99–2.14 × 106 ml-1) and larger numbers of ciliates (2.65–5.40 cells ml-1). The differences were statistically significant. The separation of the two water masses indicated that the Słupia River exerted a minor impact on the marine waters. The ciliate community composition changed along the transect studied. The main statistically significant difference observed was the low contribution of oligotrichs and choreotrichs to ciliate biomass (3–4%) in less saline waters and their dominance (45–80% of ciliate biomass) in more saline waters.

2

Growth rates of common pelagic ciliates in a highly eutrophic lake measured with a modified dilution method

Rychert K.

Oceanological and Hydrobiological Studies

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2016

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Vol. 45, No. 2

216--229

PL

The growth rates of ciliates estimated under natural conditions with the widely used size fractionation method are much lower than those observed in cultures. However, recent studies performed with a modified dilution method demonstrated that the size fractionation method underestimates the ciliate growth, because it does not remove predators of the same size as the organisms studied. Thus, it is still unresolved whether ciliates are food-limited in different systems and whether their growth rates are indeed lower than those in cultures. This study was conducted in highly eutrophic Lake Gardno using a modified dilution method. Each time, two dilution experiments were performed (around noon and around midnight). Four small, common ciliates from the genera Rimostrombidium, Tintinnidium, Cyclidium, and Urotricha were studied. The first three ciliates demonstrated very high mean diel growth rates exceeding 0.1 h-1, which corresponded well to the highest values reported in the literature for the ciliate growth in cultures at similar temperatures. Tintinnidium sp. demonstrated a diel growth rhythm. Urotricha sp. was sensitive to the experimental procedure, and measurements of its growth were unsuccessful. Concentrations of food particles were analyzed to check whether organisms studied were food satiated.

3

Annual production to biomass (P/B) ratios of pelagic ciliates in different temperate waters

Rychert K., Kozłowska J., Krawiec K., Czychewicz N., Pączkowska M., Wielgat-Rychert M.

Oceanological and Hydrobiological Studies

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2016

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Vol. 45, No. 3

388--404

EN

In aquatic environments, ciliates integrate the energy flowing through bacteria, smaller protozoa, and the prevailing fraction of algae and are further grazed upon by metazooplankton. Ciliates are incorporated into budgets and models describing ecosystem functioning. However, data for the parameterization and validation of models remain insufficient. In this study, annual production to biomass (P/B) ratios of pelagic ciliates were estimated in four lakes of different trophic status and at two sites located in the coastal zone of the Baltic Sea. All study sites were located in the temperate zone. The calculations were based on bulk data reflecting seasonal changes in ciliate production, which was estimated using an allometric equation. The annual ciliate P/B ratio for surface waters was 308 ± 81 yr-1 (mean ± standard deviation). There was no statistically significant relationship between the mean annual ciliate biomass in particular water bodies and the annual P/B ratio. In the near-bottom waters, the annual P/B ratio was 78 ± 39 yr-1. Because of the possible food limitation of ciliate growth and reconstructions of the community due to changes in environmental conditions, the ciliate P/B ratio applied in models of temperate waters should range from 50% to 100% of the P/B ratios estimated in this study.

4

Latitudinal pattern of abundance and composition of ciliate communities in the surface waters of the Atlantic Ocean

Rychert K., Nawacka B., Majchrowski R., Zapadka T.

Oceanological and Hydrobiological Studies

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2014

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Vol. 43, No. 4

4436--441

EN

Abundance, biomass, and taxonomic composition of the ciliate community were studied in the surface waters along a transect between 50°S 61°W and 48°N 5°W (Atlantic Ocean, March-April 2011). The abundance of heterotrophic ciliates was low in the equatorial zone (280–320 cells l−1, 0.11–0.12 μg C l−1), but it increased toward both the northern and southern temperate zones with the maximum abundance observed at 44°S (2667 cells l−1, 0.82 μg C l−1). This pattern resembles the global distribution of oceanic primary production, which is low at lower latitudes and high in temperate zones. In temperate zones ciliate abundance peaks during spring and fall. Thus, because the present study was carried out during spring in the northern hemisphere and austral fall in the southern hemisphere, the ciliate abundance at higher latitudes was additionally elevated. Functionally autotrophic Mesodinium rubrum was only observed in the northern hemisphere and tropical waters. Its maximum abundance was observed at 48°N (1080 cells l−1, 1.14 μg C l−1). The most frequently observed ciliates were oligotrichs and choreotrichs. Other important ciliates were haptorids (including M. rubrum) and hypotrichs.

5

Composition of protozoan communities at two sites in the coastal zone of the southern Baltic Sea

Rychert K., Spich K., Laskus K., Pączkowska M., Wielgat-Rychert M., Sojda G.

Oceanological and Hydrobiological Studies

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2013

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Vol. 42, No. 3

268--276

EN

Protozoan communities were studied in the coastal zone of the southern Baltic Sea. Stable environmental conditions and typical, bimodal seasonal changes in the protozoan biomass were observed at the sampling site in Sopot (2003–2004). At the sampling site in Ustka (2007–2008), strong benthic resuspension and irregular impacts of fresh water resulted in atypical seasonal changes in the protozoan biomass with a summer peak only. The mean annual biomass had similar values at both sites: 43.2 μg C dm−3 in Sopot and 38.6 μg C dm−3 in Ustka. The protozoan community in Sopot was dominated by ciliates (48% of the biomass), whereas in Ustka — by heterotrophic nanoflagellates (53%).

6

Impact of the inflow of Vistula river waters on the pelagic zone in the Gulf of Gdańsk

Wielgat-Rychert M., Ameryk A., Jarosiewicz A., Kownacka J., Rychert K., Szymanek L., Zalewski M., Agatova A., Lapina N., Torgunova N.

Oceanologia

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2013

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No. 55 (4)

859--886

EN

The biomass, production, composition of autotrophic phytoplankton and hetero-trophic bacteria were studied along with environmental and biological parameters. Samples were taken from Vistula river water (at Kiezmark) and from the river plume to the outer stations in the Gulf of Gdańsk (Baltic Sea) in June 2005. The phytoplankton biomass gradient appeared to be simply the result of dilution of the river water in the sea water, whereas the bacterial abundance and biomass dropped between the river station and the first sea water stations, a decrease that cannot be explained by the dilution effect. The Vistula water stimulated the production mainly of bacterioplankton but also of phytoplankton in the river plume as compared to rates measured in Vistula waters and at the open sea stations. However, this stimulation did not result in a measurable increase in biomasses, probably because of the short retention time of water in the river plume. Phytoplankton production was correlated with phytoplankton biomass (Chl a), while bacterial production was correlated with phytoplankton production and phytoplankton biomass (Chl a).

7

The importance of ciliates as a trophic link in shallow, brackish and eutrophic lakes

Rychert K., Wielgat-Rychert M., Myszka M., Krawiec K., Szczurowska D., Bochyńska M.

Polish Journal of Ecology

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2012

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Vol. 60, nr 4

767--776

EN

The importance of ciliates as a trophic link, which is defined as a fraction of the energy bound by primary producers that is transferred through the ciliate community, was assessed in the pelagic zones of shallow, eutrophic, and estuarine lakes. The study was conducted in Lake Gardno and Lake Łebsko located in northern Poland. Each of these lakes is characterized by very high mean annual ciliate biomasses of 115 μg C-1 (Lake Gardno, April 2006 – April 2007), 107 μg C L-1 (Lake Gardno, February 2007 – February 2008), 85 [mu]g C L-1 (Lake Łebsko, April – November 2007), and 127 μg C L-1 (Lake Łebsko, April – September 2008). Ciliate production was estimated using allometric equations and was compared to primary production measured with the light-and-dark bottles method. Annual, depth-integrated ciliate secondary production corresponded to 9 and 11% (Lake Gardno, two consecutive years studied) and 12% (Lake Łebsko, the same value for two growing seasons studied) of primary production. These values exceed the majority of other estimates in the literature, which indicates the high importance of ciliates in such highly-productive, shallow lakes.

8

Communities of heterotrophic protists (protozoa) in the near-bottom zone of the Gdańsk Basin

Rychert K.

Oceanological and Hydrobiological Studies

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2011

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Vol. 40, No.3

68-73

EN

Biomass and generic diversity of heterotrophic protists (protozoa) were studied in the near-bottom zone at five stations located in the inner Gulf of Gdańsk and in offshore waters during June 2002. The highest protozoan biomass was observed in the inner Gulf of Gdańsk and close to the mouth of the Vistula River. Protozoan biomass decreased offshore. In well-oxygenated waters heterotrophic flagellates constituted 39-51%, of the protozoan biomass, ciliates constituted 18-25%, and heterotrophic dinoflagellates 29-39% of the protozoan biomass. These findings confirmed previous studies that showed that a high abundance of heterotrophic dinoflagellates is a distinct feature of the Gulf of Gdańsk. At one station located in the Gdańsk Deep, where the near-bottom zone was anoxic, the contribution of heterotrophic flagellates decreased to 18% and ciliates’ share increased to 82% of the protozoan biomass. No dinoflagellates were observed in the anoxic zone.

9

Dependence between temperature and clearance rate of Balanion comatum Wulff

Rychert K.

Oceanologia

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2011

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No. 53 (2)

623-629

EN

The dependence between temperature and clearance rate of the ciliate Balanion comatum Wulff 1919 was assessed in the coastal zone of the southern Baltic Sea. Five in situ experiments were carried out with the use of wheat starch as a surrogate of food particles. The clearance rate rose from 1.4 to 7.0 μl cell-1 h-1 with a temperature rise from 8 to 19°C. B. comatum preferred particles of size 1.9-4.4 μm, and the clearance rates calculated for the preferred particles were consistently higher than those measured for the whole range of particles ingested (Wilcoxon's signed rank test, p = 0.04). The exponential dependence between temperature and clearance rates for preferred particles was statistically significant (R2 = 0.86, p = 0.02) and enabled the Q10 coefficient to be calculated. This amounted to 2.9 and lay within the range of typical values. The linear dependence (also drawn for preferred particles) demonstrated a higher significance (R2 = 0.91, p = 0.02), indicating the linear dynamics of the process.

10

Particle size selectivity of two marine ciliates - Balanion comatum Wulff and Strombidium sp.

Rychert K.

Polish Journal of Ecology

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2008

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Vol. 56, nr 2

251-257

EN

Food selectivity of marine ciliates Balanion comatum Wulff and Strombidium sp. (mean size of cell 19 [mi]m) were studied in situ during incubation with wheat starch particles as a surrogate food. Range of particles ingested by Balanion comatum was 1.25-7.50 [mi]m with preference for 3.75 [mi]m particles (statistically significant result). Strombidium sp. engulfed particles ranging from 1.25 [mi]m to 5.00 [mi]m also with preference for 3.75 [mi]m particles. In the Baltic Sea size range of particles preferred by both ciliates is dominated by nanoflagellates.

11

Nanoflagellates in the Gdańsk Basin: coexistence between forms belonging to different trophic types

Rychert K.

Oceanologia

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2006

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No. 48 (2)

323-330

EN

Nanoflagellates are important bacterivores, but their role is often underestimated because forms capable of phagotrophy and containing chlorophyll (mixotrophs) are excluded from analyses. Research conducted in the coastal zone of the Gdańsk Basin (Baltic Sea) revealed seasonal changes in the relationship between the biomasses of small (1-8 žm) nanoflagellates with (NFChl+) and without chlorophyll (NFChl-). Three distinct patterns were distinguished: (i) spring, when the biomass of NFChl+ was lower than that of NFChl-, (ii) summer and autumn, when NFChl+ were dominant (about 90%), and (iii) late autumn and winter, when the prevalence of NFChl+ was lower (71-79\%). Additional studies showed the existence of spatial differences in the composition of the nanoflagellate community. These spatial differences were not shaped by freshwater input. The possible importance of mixotrophic forms in the Gdańsk Basin is discussed.

12

The size structure of the Mesodinium rubrum population in the Gdańsk Basin

Rychert K.

Oceanologia

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2004

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No. 46 (3)

439-444

EN

The ciliate Mesodinium rubrum Lohmann 1908 (=Myrionecta rubra Jankowski 1976) is an important phototrophic organism in the Gdańsk Basin. In June 2002 the vertical distribution and size structure of the M. rubrum population were studied. Its presence was generally observed in the whole water column (one exception was the anoxic near-bottom zone in the Gdańsk Deep) at all stations studied. Maximum abundance (18300 cells dm-3) was recorded at 26 m depth at the station located in the inner Gulf of Gdańsk. Analysis of the size structure of the counted organisms demonstrated the co-existence of small and large cells of M. rubrum in the upper layer of the water column and a gradual increase with depth of the prevalence of large specimens. This shows that at least two forms of M. rubrum exist in the region studied. Deep migrations are probably undertaken only by relatively large organisms.