Wyniki wyszukiwania - Biblioteka Nauki

1

Particulate organic carbon in the southern Baltic Sea: numerical simulations and experimental data

100%

Dzierzbicka-Głowacka L. , Kuliński K. , Maciejewska A. , Jakacki J. , Pempkowiak J.

Oceanologia

|

2010

|

tom No. 52 (4)

621-648

EN

Particulate Organic Carbon (POC) is an important component in the carbon cycle of land-locked seas. In this paper, we assess the POC concentration in the Gdańsk Deep, southern Baltic Sea. Our study is based on both a 1D POC Model and current POC concentration measurements. The aim is twofold: (i) validation of simulated concentrations with actual measurements, and (ii) a qualitative assessment of the sources contributing to the POC pool. The POC model consists of six coupled equations: five diffusion-type equations for phytoplankton, zooplankton, pelagic detritus and nutrients (phosphate and total inorganic nitrogen) and one ordinary differential equation for detritus at the bottom. The POC concentration is determined as the sum of phytoplankton, zooplankton and pelagic detritus concentrations, all expressed in carbon equivalents. Bacteria are not simulated in this paper. The observed large fluctuations of POC concentrations are attributed to its appreciable seasonal variability. The maximum concentration of POC varied between 870 mgC m-3 in May and 580 mgC m-3 in September, coinciding with the period of maximum dead organic matter and phytoplankton biomass concentrations. The results of the numerical simulations are in good agreement with observed values. The difference between the modelled and observed POC concentrations is equal to 3-28% and depends on the month for which the calculations were made, although no time trend of the difference is observed. The conclusion is that the numerical simulations are a sufficiently good reflection of POC dynamics in the Baltic.

2

Numerical modelling of POC dynamics in the southern Baltic under possible future conditions determined by nutrients, light and temperature

100%

Dzierzbicka-Głowacka L. , Kuliński K. , Maciejewska A. , Jakacki J. , Pempkowiak J.

Oceanologia

|

2011

|

tom No. 53 (4)

971-992

EN

This paper discusses predictions of particulate organic carbon (POC) concentrations in the southern Baltic Sea. The study is based on the one-dimensional Particulate Organic Carbon Model (1D POC), described in detail by Dzierzbicka-Głowacka et al. (2010a). The POC concentration is determined as the sum of phytoplankton, zooplankton and dead organic matter (detritus) concentrations. Temporal changes in the phytoplankton biomass are caused by primary production, mortality, grazing by zooplankton and sinking. The zooplankton biomass is affected by ingestion, excretion, faecal production, mortality and carnivorous grazing. The changes in the pelagic detritus concentration are determined by the input of dead phytoplankton and zooplankton, the natural mortality of predators, faecal pellets, and sinks - sedimentation, zooplankton grazing and biochemical decomposition. The model simulations were done for selected locations in the southern Baltic Sea (Gdańsk Deep, Bornholm Deep and Gotland Deep) under predicted conditions characterized by changes of temperature, nutrient concentrations and light availability. The results cover the daily, monthly, seasonal and annual POC concentration patterns in the upper water layer. If the assumed trends in light, nutrients and temperature in the southern Baltic correctly predict the conditions in 2050, our calculations indicate that we can expect a two- to three-fold increase in POC concentration in late spring and a shift towards postponed maximum POC concentration. It can also be anticipated that, as a result of the increase in POC, oxygenation of the water layer beneath the halocline will decrease, while the supply of food to organisms at higher trophic levels will increase.

3

Numerical simulations of marine zooplankton dynamics and its interaction with other system components

88%

Dzierzbicka-Głowacka L.

Polish Journal of Ecology

|

2001

|

tom Vol. 49, nr 1

3-18

EN

This paper presents the numerical simulations of the influence of the zooplankton dynamics on the phytoplankton, zooplankton and nutrient biomasses in the sea. The numerical studies were carried out using a phytoplanktonzooplankton-nutrient-detrius PhyZooNuDe biological upper layer model with a full-developed regeneration mechanism and with regarding daily migration of zooplankton. In this model the zooplankton is treated not as "biomass" but as organisms having definite patterns of growth, reproduction, and mortalityassuming, also {Zoop} is composed of (i) cohorts of copepods with weights (W[i]) and numbers (Z[i]); then {Zoop} = SigmaW[i]Z[i]. The PhyZooNuDe model consists of three coupled, partial second-order differential equations of the diffusion type for phytoplankton, zooplankton, nutrients and one ordinary first-order differential equation for benthic detritus pool, together with initial and boundary conditions. The calculation were made for 35 days in an area 0 mniejsze lub równe z mniejsze lub rowne 20m with a vertical space step of 10 cm and a time step of 5 min. The experimental data, gathered during the PEX'86 international scientific experiment of the Baltic states, and subsequently by the International Council for the Exploration of the Sea, were used as the input data for the calculations. The simulation given here demonstrated as factors of grazing, growth, metabolism, reproduction, and mortality of copepods are important since can alter the nature of the interactions of plants and herbivores.

4

Leaf litter diversity leads to non-additivity in stream detritivore colonization dynamics

88%

Swan C. M. , Palmer M. A.

Oceanological and Hydrobiological Studies

|

2005

|

tom Vol. 34, No.3

19--38

EN

Resource heterogeneity in the lake littoral zones and streams often takes the form of leaf litter diversity. Since resource quality varies between leaf species, diversity of leaf litter inputs to these systems may alter detritivore dynamics. We challenged the assumption that stream detritivores view their leaf resources independently, and that shredder colonization dynamics were additive. We developed a null model that suggests the temporal coefficient of variation in abundance of detritivores declines as leaf diversity increases. We then conducted an experiment in which leaf composition was manipulated in a stream and shredder abundance was followed. Shredder stability was low on single leaf species, increased at intermediate levels, then declined at maximum levels. The null model did not predict the low stability observed, suggesting other ecological factors influenced shredder abundance. Non-additive patterns in colonization support the notion that leaf diversity leads to emergent properties, altering consumer dynamics in this ecosystem.

5

Detrital components in submontane organogenic springs in relation to their morphology, microhabitats and macroinvertebrates

75%

Ticha K. , Simon O. P. , Douda K. , Kubikova L.

Polish Journal of Ecology

|

2012

|

tom 60

|

nr 1

EN

Fine particulate organic matter (FPOM), originated by aggregation of smaller particles and by decomposition of bigger particles, usually presents the dominant energy and nutrient source in the primary river net. Relationships between detrital components, environmental factors and macroinvertebrate composition were investigated in 52 submontane organogenic spring areas in small catchment in the Šumava foothills, Czech Republic. All three types of springs (helocrenes rheocrenes and limnocrenes) were represented, as well as springs with the transitional character. The selected springs were permanent, with water discharge higher than 0.1 L s-1, they all were coldwater and stenothermic, with the winter water temperature at the point of the source ranging from 2.0 to 9.9°C. At each spring area, the main morphological and physical characteristics of the spring and surrounding area were recorded. Samples of detritus were collected (using the 2 mL sampling tube) from up to 5 microhabitats at each spring, usually macrophyte vegetation, point of the source, detrital deposition, sand, algal mat, leaf litter or moss, accordingly to the microhabitats, which were present. Macroinvertebrates were semiquantitatively sampled using a 15-cm circular sampler with 0.8 mm mesh, to the orders or lower taxa were determined. Water samples were taken, and analyses of the main physico-chemical factors were carried out. In our set of springs, organic substrate prevailed. Only small differences in the physico-chemical parameters (e.g. pH = 5.96 ± 0.39; mean ± SD) and low concentrations of nutrients (e.g. N-NO3 - = 0.79 ± 0.86 mg L-1, ortho-PPO4 - = 0.0336 ± 0.0275 mg L-1) were noted, whereas studied geomorphological parameters and microhabitat types were more diverse. The proportion of basic microscopically differentiable components of the detritus was similar in all spring types and microhabitats. In all study sites, faecal pellet content was dominant in the detritus (49%) followed by plant residuals (26%) and amorphous matter (21%). High faecal pellet content is considered to be a consequence of a steadily low temperature in the springs. The correlation among the presence of macroinvertebrate groups and particular detrital components content was not significant, except for Trichoptera; the abundance of this group was positively correlated with the proportion of plantv residuals in detritus in vegetation microhabitats. Faecal pellet content showed a weak negative correlation with N-NH4 concentration, which is probably the result of faster faecal pellet decomposition in springs with higher N-NH4 contents.

6

Detrital components in submontane organogenic springs in relation to their morphology, microhabitats and macroinvertebrates

75%

Ticha K. , Simon O. , Douda K. , Kubikova L.

Polish Journal of Ecology

|

2012

|

tom Vol. 60, nr 1

163-175

EN

Fine particulate organic matter (FPOM), originated by aggregation of smaller particles and by decomposition of bigger particles, usually presents the dominant energy and nutrient source in the primary river net. Relationships between detrital components, environmental factors and macroinvertebrate composition were investigated in 52 submontane organogenic spring areas in small catchment in the Sumava foothills, Czech Republic. All three types of springs (helocrenes, rheocrenes and limnocrenes) were represented, as well as springs with the transitional character. The selected springs were permanent, with water discharge higher than 0.1 L s[^-1], they all were coldwater and stenothermic, with the winter water temperature at the point of the source ranging from 2.0 to 9.9[degrees]C. At each spring area, the main morphological and physical characteristics of the spring and surrounding area were recorded. Samples of detritus were collected (using the 2 mL sampling tube) from up to 5 microhabitats at each spring, usually macrophyte vegetation, point of the source, detrital deposition, sand, algal mat, leaf litter or moss, accordingly to the microhabitats, which were present. Macroinvertebrates were semiquantitatively sampled using a 15-cm circular sampler with 0.8 mm mesh, to the orders or lower taxa were determined. Water samples were taken, and analyses of the main physico-chemical factors were carried out. In our set of springs, organic substrate prevailed. Only small differences in the physico-chemical parameters (e.g. pH = 5.96 [plus or minus] 0.39; mean [plus or minus] SD) and low concentrations of nutrients (e.g. N-NO3[^-] = 0.79 [plus or minus] 0.86 mg L[^-1], ortho-PPO4[^-] = 0.0336 [plus or minus] 0.0275 mg L[^-1]) were noted, whereas studied geomorphological parameters and microhabitat types were more diverse. The proportion of basic microscopically differentiable components of the detritus was similar in all spring types and microhabitats. In all study sites, faecal pellet content was dominant in the detritus (49%) followed by plant residuals (26%) and amorphous matter (21%). High faecal pellet content is considered to be a consequence of a steadily low temperature in the springs. The correlation among the presence of macroinvertebrate groups and particular detrital components content was not significant, except for Trichoptera; the abundance of this group was positively correlated with the proportion of plant residuals in detritus in vegetation microhabitats. Faecal pellet content showed a weak negative correlation with N-NH4 concentration, which is probably the result of faster faecal pellet decomposition in springs with higher N-NH4 contents.

7

Leaf litter diversity leads to non-additivity in stream detritivore colonization dynamics

75%

Swan C. M. , Palmer M. A.

Oceanological and Hydrobiological Studies

|

2005

|

tom 34

|

nr 3

8

Leaf litter decomposition and invertebrate colonization in Alpine environments above the tree line: an experimental study

63%

Bo T. , Cammarata M. , Lopez-Rodriguez M. J. , Tierno de Figueroa J. M. , Fenoglio S.

Polish Journal of Ecology

|

2014

|

tom 62

|

nr 2

EN

Recent studies suggested a general warming trend in the Alps, resulting in a significant migration of forests to altitudes higher than the usual, regional tree line. As a consequence, some headwater streams will likely receive more allochthonous organic matter. For this reason, the dynamics of decomposition of terrestrial leaf detritus in stream reaches that naturally lacked this resource represents a subject of considerable interest, on which no information is currently available. The aim of this study was to analyse breakdown and macroinvertebrate colonisation of leaf bags in an Alpine headwater stream above the tree line. Results of this study indicate that decomposition of terrestrial leaves in a lotic alpine environment above the tree line takes place through a process similar to what happens at lower altitudes, but with some differences. The reduced rate of decomposition observed may be due to lower temperatures. At lower altitudes, tree cover provides a supply of organic material sufficient to support a rich guild of shredders. This study demonstrates that also above tree line, where communities are dominated by scrapers, an important part of the benthic community take part in the decomposition process of leaves. We can conclude that streams above the tree line, while hosting invertebrate communities dominated by rhithrophilous organisms that feed mostly on biofilm, also harbour a rich population of opportunist invertebrates. It seems that, in the case of expected temperature increase at higher altitudes , terrestrial organic detritus may be actively degraded by lotic benthic communities.

9

Charakterystyka żużli i popiołów lotnych pochodzących z elektrociepłowni Tychy.

63%

Zapadka-Żurek B.

Prace Naukowe Instytutu Górnictwa Politechniki Wrocławskiej. Konferencje

|

2007

|

tom Vol. 120, nr 49

335-344

PL

Praca zawiera identyfikację form morfologicznych niespalonej materii organicznej pozostających w żużlach i popiołach lotnych, określenie ich zawartości oraz porównanie ich form z zawartością części palnych. Stwierdzono częste występowanie cenosfer i koronek w popiołach, a form masywnych w żużlach. Słaba korelacja pomiędzy zawartością części palnych, a zawartością form morfologicznych przypuszczalnie wynika z warunków spalania.

EN

The research presents the identification of char morphological forms in slags and fly ashes, determination of their quantity, comparison between their morphology and the unburned organic matter content. Cenospheres and laces are frequently present in ashes and massive forms are frequently present in slags. The weak correlation between the content of unburned organic matter and the content of char morphological forms probably can be related to combustion conditions.

10

Numerical simulations of marine zooplankton dynamics and its interaction with other system components

63%

Dzierzbicka-Glowacka L.

Polish Journal of Ecology

|

2001

|

tom 49

|

nr 1

11

Dynamics of seasonal changes of overground plant biomass in two meadow communities of the Kampinos National Park

63%

Pasternak-Kusmierska D.

Polish Ecological Studies

|

1996

|

tom 22

|

nr 1-2

12

Fauna Uropodina (Acari: Mesostigmata) spróchniałych pni drzew i dziupli w Polsce

62%

Bloszyk J.

Zeszyty Problemowe Postępów Nauk Rolniczych

|

1990

|

tom 373

RU

Автор рассматривает результаты исследований фауны клещей Uropodina истлевших пней и дупел деревьев в Польше. В исследуемом материале охватывающем 188 образцов он обнаружил наличие 41 вида указанных клещей общим числом 2102 особей (табл. 1). Автор характеризует фауну клещей Uropodina исследуемых мероце- нозов и обсуждает сходство видового состава этой фауны в зависимости от вида дерева.

EN

Results of investigations of the fauna of Uropodina mites of decayed tree stumps and hollows in Poland are presented by the author. Occurrence of 41 species with 2102 specimens of the mites as mentioned above were found by him in the material investigated comprising 188 samples (Table 1). The characteristics of the Uropodina mites of the merocenoses under study is presented and similarity of the species composition of this fauna depending on the tree kind is discussed.

13

Numerical modelling of POC dynamics in the Southern Baltic under possible future conditions determined by nutrients, light and temperature

51%

Dzierzbicka-Glowacka L. , Kulinski K. , Maciejewska A. , Jakacki J. , Pempkowiak J.

Oceanologia

|

2011

|

tom 53

|

nr 4

EN

This paper discusses predictions of particulate organic carbon (POC) concentra- tions in the southern Baltic Sea. The study is based on the one-dimensional Particulate Organic Carbon Model (1D POC), described in detail by Dzierzbicka- Głowacka et al. (2010a). The POC concentration is determined as the sum of phytoplankton, zoo- plankton and dead organic matter (detritus) concentrations. Temporal changes in the phytoplankton biomass are caused by primary production, mortality, grazing by zooplankton and sinking. The zooplankton biomass is affected by ingestion, excretion, faecal production, mortality and carnivorous grazing. The changes in the pelagic detritus concentration are determined by the input of dead phytoplankton and zooplankton, the natural mortality of predators, faecal pellets, and sinks – sedimentation, zooplankton grazing and biochemical decomposition. The model simulations were done for selected locations in the southern Baltic Sea (Gdańsk Deep, Bornholm Deep and Gotland Deep) under predicted conditions characterized by changes of temperature, nutrient concentrations and light availability. The results cover the daily, monthly, seasonal and annual POC concentration patterns in the upper water layer. If the assumed trends in light, nutrients and temperature in the southern Baltic correctly predict the conditions in 2050, our calculations indicate that we can expect a two- to three-fold increase in POC concentration in late spring and a shift towards postponed maximum POC concentration. It can also be anticipated that, as a result of the increase in POC, oxygenation of the water layer beneath the halocline will decrease, while the supply of food to organisms at higher trophic levels will increase.

14

Particulate organic carbon in the Southern Baltic Sea: numerical simulations and experimental data

51%

Dzierzbicka-Glowacka L. , Kulinski K. , Maciejewska A. , Jakacki J. , Pempkowiak J.

|

nr 4

EN

Particulate Organic Carbon (POC) is an important component in the carbon cycle of land-locked seas. In this paper, we assess the POC concentration in the Gdańsk Deep, southern Baltic Sea. Our study is based on both a 1D POC Model and current POC concentration measurements. The aim is twofold: (i) validation of simulated concentrations with actual measurements, and (ii) a qualitative assessment of the sources contributing to the POC pool. The POC model consists of six coupled equations: five diffusion-type equations for phytoplankton, zooplankton, pelagic detritus and nutrients (phosphate and total inorganic nitrogen) and one ordinary differential equation for detritus at the bottom. The POC concentration is determined as the sum of phytoplankton, zoo-plankton and pelagic detritus concentrations, all expressed in carbon equivalents. Bacteria are not simulated in this paper. The observed large fluctuations of POC concentrations are attributed to its appreciable seasonal variability. The maximum concentration of POC varied between 870 mgC m−3 in May and 580 mgC m−3 in September, coinciding with the period of maximum dead organic matter and phytoplankton biomass concentrations. The results of the numerical simulations are in good agreement with observed values. The difference between the modelled and observed POC concentrations is equal to 3–28% and depends on the month for which the calculations were made, although no time trend of the difference is observed. The conclusion is that the numerical simulations are a ufficiently good reflection of POC dynamics in the Baltic.

15

Food and feeding of Viviparus viviparus [L.] [Gastropoda] in dam reservoir and river habitats

51%

Jakubik B.

Polish Journal of Ecology

|

2009

|

tom 57

|

nr 2

321-330

EN

Studies on feeding of V. viviparus were carried out in the years 1995–2005 in dam reservoir (Zegrzyński Reservoir, Central Poland, 60 km long, mean depth ca 3.5 m, maximum depth at the dam up to 9 m, mean retention time from 1 to 15 days) and in the outlets of its tributaries (the Bug, Narew and Rządza rivers), in the Narew River and – in the years 2003–2006 – also in oxbow lakes of the Bug River. Sex ratio and size structure of snails were estimated. Both the content of intestines (detritus, algae, inorganic matter) and the gut fulfilment were analysed. Performed multi-factor analysis showed the effect of habitat, season and snail size (estimated from shell height) on food mass in the gut. Snails from dam reservoir and outlet stretches of three rivers showed the largest food mass in the gut. Intestines of snails from rivers and oxbow lakes were less filled. The largest food volumes were found in spring and summer. Only in viviparids from oxbow lakes the largest food mass in the gut was noted in the autumn. Food mass in the gut was largest in snails of the I (<8 mm) and IV (20–35 mm) size class. Food mass was similar in females and males. Differences were, however, noted in the ingested food mass between fertile and infertile females which was smaller in the former. In all studied sites the snails fed mainly on detritus which constituted from 70 to 90% of food mass ingested of all individuals. Detritus abundance in studied habitats might result in using it by snails as obligatory though low-energetic food source. Detritus contributed more to the food of viviparids from Zegrzyński Reservoir and from oxbow lakes, slightly less – to the food of those from outlet stretches of rivers and from the Narew River. Algae contributed from 5% (Zegrzyński Reservoir) to 15% (the Narew River) to the food mass in snail guts. Apart from diatoms, green algae, dinoflagellates and chrysophytes, also cyanobacteria were found in snail food mass. Green algae (46% of all algae) and diatoms (37% of all algae) constituted the largest part of viviparids algal diet in the reservoir. The share of chrysophytes and dinoflagellates made about 10%. More diatoms (up to 48%) and less green algae (up to 25%) were found in snails from outlet stretches of rivers. Guts of snails from the Narew River contained mainly diatoms (over 50%) and green algae (30%). Gut content of snails from oxbow lakes was dominated by green algae (50% of all algae) and diatoms (35% of all algae). Inorganic matter in a form of mineral particles contributed least to the food of snails in the reservoir and in oxbow lakes (ca 5%) in comparison with snails from other sites. No food of animal origin was found. In general, it can be stated that the amount of food mass ingested and its composition differed rather slightly among studied habitats, seasons and individuals.

16

Heavy metal concentrations (Co, Zn, Mn, Fe, Pb AND Cd) in molluscs from the Zegrzyński Reservoir (central Poland) as compared with their levels in other element s of the ecosystem

51%

Jurkiewicz-Karnkowska E. , Królak E.

Chemia i Inżynieria Ekologiczna

|

2000

|

tom Vol. 7, nr 11

1189-1198

EN

Concentrations of copper, zinc, manganese, iron, cadmium and lead were investigated in chosen mollusc species from the Zegrzyński Reservoir (Central Poland) against the background of metal content in water, seston, bottom sediments, macrophytes, periphyton, and detritus. These concentrations were generally comparable to values reported from environments slightly contaminated with heavy metals. Relatively small interspecific variation in accumulation of non-essential metals (Pb, Cd) distinctly lower than in the case of essential metals resulted mainly from the lack of regulation of their level in an organism. It is conducive to molluscs application in bioindication of environmental contamination with Pb and Cd.

PL

Badano stężenie miedzi, cynku, manganu, żelaza, kadmu i olowiu w tkankach miękkich i muszlach wybranych gatunków mięczaków ze Zbiornika Zegrzyńskiego na tle ich poziomu w wodzie, sestonie, osadach dennych, makrofitach, peryfitonie i detrytusie. Stężenia te osiągały na ogół wartości porównywalne do podawanych ze środowisk w niewielkim stopniu zanieczyszczonych metalami ciężkimi. Stosunkowo małe zróżnicowanie gatunkowe kumulacji metali ksenobiotycznych (Pb i Cd) w badanych ślimakach i małżach (dużo mniejsze, niż w przypadku metali biofilnych) wynikające głównie z braku regulacji poziomu tych pierwiastków w organizmie sprzyja wykorzystaniu mięczaków w bioindykacji skażenia badanego ekosystemu ołowiem i kadmem.-

17

Processes regulating pCO2 in the surface waters of the Central Eastern Gotland Sea: a model study

51%

Kuznetsov I. , Neumann T. , Schneider B. , Yakushev E.

Oceanologia

|

2011

|

tom 53

|

nr 3

EN

This work presents a one-dimensional simulation of the seasonal changes in CO2 partial pressure (pCO2). The results of the model were constrained using data from observations, which improved the model’s ability to estimate nitrogen fixation in the central Baltic Sea and allowed the impact of nitrogen fixation on the ecological state of the Baltic Sea to be studied. The model used here is the public domain water-column model GOTM (General Ocean Turbulence Model), which in this study was coupled with a modifed Baltic Sea ecosystem model, ERGOM (The Baltic Sea Research Institute’s ecosystem model). To estimate nitrogen fixation rates in the Gotland Sea, the ERGOM model was modified by including an additional cyanobacteria group able to fix nitrogen from March to June. Furthermore, the model was extended by a simple CO2 cycle. Variable C:P and N:P ratios, controlled by phosphate concentrations in ambient water, were used to represent cyanobacteria, detritus and sediment detritus. This approach improved the model’s ability to reproduce sea-surface phosphate and pCO2 dynamics. The resulting nitrogen fixation rates in 2005 for the two simulations, with and without the additional cyanobacteria group, were 259 and 278 mmol N m−2 year−1 respectively.

18

Food and feeding of Viviparus viviparus (L.) (Gastropoda) in dam reservoir and river habitats

51%

Jakubik B.

Polish Journal of Ecology

|

2009

|

tom Vol. 57, nr 2

321-330

EN

Studies on feeding of V. viviparus were carried out in the years 1995-2005 in dam reservoir (Zegrzyński Reservoir, Central Poland, 60 km long, mean depth ca 3.5 m, maximum depth at the dam up to 9 m, mean retention time from 1 to 15 days) and in the outlets of its tributaries (the Bug, Narew and Rządza rivers), in the Narew River and - in the years 2003-2006 - also in oxbow lakes of the Bug River. Sex ratio and size structure of snails were estimated. Both the content of intestines (detritus, algae, inorganic matter) and the gut fulfilment were analysed. Performed multi-factor analysis showed the effect of habitat, season and snail size (estimated from shell height) on food mass in the gut. Snails from dam reservoir and outlet stretches of three rivers showed the largest food mass in the gut. Intestines of snails from rivers and oxbow lakes were less filled. The largest food volumes were found in spring and summer. Only in viviparids from oxbow lakes the largest food mass in the gut was noted in the autumn. Food mass in the gut was largest in snails of the I (<8 mm) and IV (20-35 mm) size class. Food mass was similar in females and males. Differences were, however, noted in the ingested food mass between fertile and infertile females which was smaller in the former. In all studied sites the snails fed mainly on detritus which constituted from 70 to 90% of food mass ingested of all individuals. Detritus abundance in studied habitats might result in using it by snails as obligatory though low-energetic food source. Detritus contributed more to the food of viviparids from Zegrzyński Reservoir and from oxbow lakes, slightly less - to the food of those from outlet stretches of rivers and from the Narew River. Algae contributed from 5% (Zegrzyński Reservoir) to 15% (the Narew River) to the food mass in snail guts. Apart from diatoms, green algae, dinoflagellates and chrysophytes, also cyanobacteria were found in snail food mass. Green algae (46% of all algae) and diatoms (37% of all algae) constituted the largest part of viviparids algal diet in the reservoir. The share of chrysophytes and dinoflagellates made about 10%. More diatoms (up to 48%) and less green algae (up to 25%) were found in snails from outlet stretches of rivers. Guts of snails from the Narew River contained mainly diatoms (over 50%) and green algae (30%). Gut content of snails from oxbow lakes was dominated by green algae (50% of all algae) and diatoms (35% of all algae). Inorganic matter in a form of mineral particles contributed least to the food of snails in the reservoir and in oxbow lakes (ca 5%) in comparison with snails from other sites. No food of animal origin was found. In general, it can be stated that the amount of food mass ingested and its composition differed rather slightly among studied habitats, seasons and individuals.

19

Chemical changes and nutrient release during decomposition processes of mature leaves of Nuphar lutea [L.] Sibith. and Sm under laboratory conditions

51%

Klink A.

International Journal of Ecohydrology and Hydrobiology

|

2005

|

tom 05

|

nr 3

215-222

20

Numerical studies of the influence of the benthic detritus pool on the chlorophyll a concentration in a stratified sea

51%

Dzierzbicka-Glowacka L. , Zielinski A.

Oceanologia

|

1997

|

tom 39

|

nr 4