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Role of psammon microinvertebrates in phosphorus cycling in hydroarenal of an eutrophic lake

Ejsmont-Karabin J., Gorelysheva Z., Kalinowska K., Rybak J.

Polish Journal of Ecology

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2012

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Vol. 60, nr 3

455-462

EN

Inorganic phosphorus released from littoral bottom sediments plays significant role in phosphorus budget of a whole ecosystem. An aim of the study was to assess a role of small invertebrates in phosphorus remineralization in hydroarenal (See Fig.1 in Preface). Hydropsammon organisms (i.e. bacteria, algae, ciliates, rotifers and crustaceans) living in a layer of submerged sands along the edge of a lake (=hydroarenal) were studied in psammolittoral of the deep, eutrophic Lake Mikołajskie (North-eastern Poland) in 2005. Sampling cores were taken at a station 1.5 m from water.s edge once or twice a month since April until October 2005. Each time three samples were taken: 5-cm thick water layer (AWL - adjacent water layer), 0.5-cm thick layer of water and sand from the transitory level (EPIH - epihydroarenal) and 2-cm thick slice of sand (ENDOH - endohydroarenal). The rate of phosphorus excretion was calculated using the appropriate regression equations expressing the relation between individual weight of organism and P excretion adjusted to the ambient temperature. Phosphorus remineralization by the psammon community (calculated for all ciliates, rotifers and crustaceans) was ca. 10 times higher than the maximum rate noted in lake pelagial. The most important role in the process was played by small ciliates, and in periods of high remineralization rate - by small cladocerans. Omnivores, feeding mostly on bacteria and small algae, played the most important role in all three studied layers, especially in periods of the highest rate of P remineralization, thus all kinds of food were used and mineralized. Predators do not seem to play significant role in P remineralization. In hydroarenal significant role seems to be played by processes involved in microbial loop. This suggestion is supported by strong domination of ciliates, main consumers of nanoflagellates, in the process of P remineralization. It seems that phytopsammon and psammic bacteria demands for phosphorus cannot be satisfied merely through the in situ remineralization by microinvertebrates.

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Biomass distribution and dynamics and food web relations in psammon community of a eutrophic lake

Kalinowska K., Ejsmont-Karabin J., Gorelysheva Z., Rybak J.

Polish Journal of Ecology

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2012

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Vol. 60, nr 3

443-453

EN

Organisms living in submerged sand along the shore and below the water's edge in freshwater lake beaches create community called hydropsammon (see Fig. 1 in Preface). Trophic relations between psammon food web components are essential in energy flow, nutrient cycling and functioning of aquatic environments. The seasonal changes in algal, bacterial, nanoflagellate, ciliate, rotifer and crustacean biomass were investigated in hydroarenal (submerged sand) of the eutrophic Lake Mikołajskie (Poland). Sampling cores were taken once or twice a month since April till October 2005 from three layers: adjacent water layer (AWL), layer of water and sand from the transitory level (EPIH - epihydroarenal) and slice of sand (ENDOH . endohydroarenal). The mean annual phytopsammon biomass was extremely high in all microlayers. Bacterial biomass was the highest in the ENDOH. Biomass of nanoflagellates was 4 to 8 times lower than that of bacteria and was the highest in the AWL. The highest mean annual biomass of ciliates was recorded in the EPIH, whereas rotifers dominated in the ENDOH. In contrast, average biomass of Crustacea was the highest in the AWL. Crustaceans dominated heterotrophic biomass in the AWL and EPIH (92 and 54% of the total biomass, respectively) whereas bacteria definitely prevailed in the ENDOH (57%). The ratios of autotrophic to heterotrophic biomass and prey to predator biomass as well as trophic relations between the studied groups of psammon organisms differed clearly among microlayers. The AWL was characterised by the lowest autotrophic/heterotrophic and predator/prey biomass ratios (about 2) and significant positive correlations between nanoflagellates and ciliates as well as between protists and both rotifers and copepods. The highest autotrophic/heterotrophic and predator/prey biomass ratio (14 and 40, respectively) and lack of correlations was found in the ENDOH. These results may suggest that the pressure of consumers was weaker in the hydroarenal layers than in the AWL. In addition, it seems that psammon ciliates, rotifers and crustaceans inhabiting the ENDOH were probably limited by factors other than food availability. In contrast to the pelagic ecosystems, autotrophic biomass exceeded heterotrophic biomass, especially in the ENDOH.

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Psammon algae: composition and spatial distribution in hygroarenal of eutrophic lake

Kalinowska K., Gorelysheva Z., Ejsmont-Karabin J.

Polish Journal of Ecology

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2011

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Vol. 59, nr 1

193-200

EN

Psammon habitats like freshwater sandy shores are the peculiar sites due to high fluctuation of physico-chemical conditions and due to the specific composition of the organisms communities distributed along the horizontal pattern related to the wave action. Taxonomic composition, numbers and biomass of phytopsammon were studied in hygroarenal (shore sand beach wetted by lake waves) of the small beach of the eutrophic Lake Mikołajskie (area 498 ha, max. depth 26 m) (Masurian Lake District, Poland). Samples were collected on one occasion (26 June 2003) from 30 sampling stations distributed parallel to lake shore along 10 m line at three different distances (sampling points A, B, C) from 0 to 60 cm from water line. The studies showed distinct horizontal distribution of psammon algae. Their numbers and biomass varied from 2.22 to 31.85 x 10[^3] cm[^-3] of sand and from 0.49 to 4.69 [my]g cm[^-3] of sand, respectively. Mean numbers in all sampling distances were very similar, while the biomass increased with increasing distance from water line. Cyanoprokaryota, among which Oscillatoria spp. were most numerous species, dominated in the numbers, whereas Bacillariophycea (mainly Stephanodiscus hantzschii Grun. and Fragillaria spp.) constituted significant proportion of the total algae biomass. There were no significant correlations between abundance of algae and size fractions of sand. Among taxonomic groups, only the biomass of Cyanoprokaryota showed positive correlations with trophic parameters (TP, TN). The studies did not show any correlations between phytopsammon and the abundances of ciliates and rotifers, suggesting that different environmental factors as well as organisms of the higher trophic levels may play a decisive role in the development and horizontal distribution of algae in hygroarenal of the beach of the eutrophic lake.

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Role of zooplankton (Ciliata, Rotifera and Crustacea) in phosphorus removal from cycling : lakes of the river Jorka watershed (Masurian Lakeland, Poland)

Ejsmont-Karabin J., Gorelysheva Z., Kalinowska K., Węgleńska T.

Polish Journal of Ecology

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2004

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Vol. 52, nr 3

275-284

EN

According to a theory of lake restoration through foot web manipulation, the removal of planktivorous fish results in the development of large cladocerans (mostly daphnids) and, consequently, in reduction of algal biomass. However, as a rule, publications devoted to different aspects of the theory completely neglected other groups of plankton invertebrates, thought they may reach very high densities. Investigations carried out in five Masurian lakes differing in trophic state and mixis showed that in most lakes the role of small cladocerans, copepods, rotifers and protozoans in the consumption of algal food and nutrient regeneration was more important than the role of large daphnids. Daphnia cucullata played more significant role (excreting 28% of the regenerated P) during "clear water phase" only in one lake - Lake Głębokie. In the remaining lakes more important was an impact of Bosmina longirostris (11-59% of the regenerated P), younger stages of cyclopoids (23%), ciliate Strobilidium humile (20%) or detritophagous rotifer Keratella cochlearis (21%). Evidenced in many papers special role of large cladocerans in clearing lake water is explained by their combined direct (by "efficient" filtering) and indirect (suppression of ciliates and rotifers through predation, interference and resource competition) impact on nutrient sedimentation or exclusion from internal cycling.