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1

Effect of dispersal in single-species discrete diffusion systems with source-sink patches

Elbetch Bilel

Mathematica Applicanda

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2023

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Vol. 51, no. 1

51--97

EN

A multi-patch source-sink model with and without intraspecific competition in the sink patches is considered. First, we study the dynamics of the model when the matrix of migration is irreducible and reducible. We show that, there is a threshold number of source patches such that the population potentially becomes extinct below the threshold and established above the threshold. Next, used the theory of singular perturbation and theorem of Tikhonov, in the case of perfect mixing, i.e. when the diffusion rate tends to infinity, we calculate the equilibrium of the model and we give a good approximations of the solutions in this case. Second, we determine, in some particular cases, the conditions under which fragmentation and the existence of sink patches can lead to a total equilibrium population greater or smaller than the sum of the carrying capacities of the source patches. Finally, we study the effect of the rapid growth of the population in source patches and the rapid death of the population in sink patches on the dynamics of the total equilibrium population and on the coexistence of the populations in the patches.

PL

Rozważany jest model wielogatunkowy enklaw wykluczanych ekologicznie z i bez konkurencji wewnątrzgatunkowej w enklawach zanikających. Najpierw badamy dynamikę modelu, gdy macierz migracji jest nieredukowalna i edukowalna. Pokazujemy, że istnieje progowa liczba enklaw, która powoduje, że populacja potencjalnie wymiera poniżej progu i jest ustablilizowana powyżej pewnego pozomu. Następnie, korzystając z teorii perturbacji pojedynczych i twierdzenia Tichonowa, w przypadku doskonałego mieszania, tj. gdy współczynnik dyfuzji dąży do nieskończoności, obliczamy równowagę modelu i podajemy dobre przybliżenia rozwiązań w tym przypadku. Po drugie, określamy, w pewnych szczególnych przypadkach, warunki, w których fragmentacja i istnienie enklaw może prowadzić do tego, że całkowita populacja w równowadze jest większa lub mniejsza niż suma populacji enklaw. Wreszcie, badamy wpływ szybkiego wzrostu populacji źródłowej i szybkiego wymierania populacji populacji zlewowej na dynamikę całkowitej populacji równowagi i na koegzystencję gatunków.

2

Demographics of great sturgeon (Huso huso) in Iranian waters of the Caspian Sea (2008–2010)

Bakhshalizadeh Shima, Bani Ali, Abdolmalaki Shahram, Ponce Palafox Jesus T.

Oceanological and Hydrobiological Studies

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2021

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Vol. 50, No. 3

325--332

EN

Demographic data of the great sturgeon, Huso huso, from the Iranian coastal waters of the Caspian Sea were derived from measurements of individuals with a fork length ranging from 84 to 255 cm, obtained from commercial fisheries. The maximum age of fish caught in the south Caspian Sea was 30 years. The estimates of the asymptotic length L∞ and the growth coefficient (K) were 265.255 cm and 0.062 per year for males and 275.78 cm and 0.08 per year for females, respectively. Total mortality rates obtained by Gulland's method were larger for males (0.64) than for females (0.46). Annual mortality rates were calculated as 47% for males and 37% for females. Data obtained in this study and their comparison with data from previous studies indicate that the great sturgeon stock is definitely exploited in an unsustainable manner.

3

Revisiting the Logistic Growth with Random Disturbances

Klimasara Paweł

Mathematica Applicanda

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2019

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Vol. 47, no. 2

177--186

EN

We reconsider a one-dimensional probabilistic model of a fire-induced tree-grass coexistence in savannas introduced by D'Odorico, Laio and Ridol in [5]. We rewrite it as a logistic growth model with random tree biomass losses caused by fire occurring at random times. We study it by using the stochastic semigroup theory and we give new suffcient conditions for the existence and stability of a unique stationary density of woody biomass.

PL

Modele populacyjne oparte o równanie logistyczne wciąż są popularne w modelowaniu ekosytemów i pozwalają lepiej zrozumieć różne zjawiska. W tym artykule rozważamy prosty 1-wymiarowy model sawanny zaproponowany przez D'Odorico, Laio i Ridolfi'ego w pracy [5], który jest modelem współistnienia traw i drzew na sawannach indukowanego losowymi pożarami. Jednak zamiast wprowadzać ubytki biomasy spowodowane występowaniem pożarów bezpośrednio do równań modelu, definiujemy odpowiedni proces stochastyczny. Następnie badamy go z wykorzystaniem teorii półgrup stochastycznych. Zasadniczym wynikiem jest twierdzenie 3.1 określające, kiedy przedstawiony model może opisywać stabilne współistnienie traw i drzew charakterystyczne dla sawann. Mianowicie przy spełnionym warunku (7) istnieje jedyny absolutnie ciągły rozkład stacjonarny biomasy drzew, do którego cały układ będzie dążył, natomiast w sytuacji (8) taki rozkład nie istnieje. Powyższy wynik można łatwo przenieść na wyższe wymiary i zastosować np. w dwuwymiarowym modelu podanym w poprzedniej pracy (na ten temat) autora i Marty Tyran-Kamińskiej [7].

4

Controllability of a class of infinite dimensional systems with age structure

Maity Debayan, Tucsnak Marius, Zuazua Enrique

Control and Cybernetics

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2019

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Vol. 48, No. 2

231--260

EN

Given a linear dynamical system, we investigate the linear infinite dimensional system obtained by grafting an age structure. Such systems appear essentially in population dynamics with age structure when phenomena like spatial diffusion or transport are also taken into consideration. We first show that the new system preserves some of the wellposedness properties of the initial one. Our main result asserts that if the initial system is null controllable in a time small enough then the structured system is also null controllable in a time depending on the various involved parameters.

5

Long-Term Changes in Population Density of Nest-Box Breeding Great Tits and Blue Tits in Two Contrasting Habitats in Central Poland

Glądalski M., Wawrzyniak J., Bańbura M., Kaliński A., Markowski M., Skwarska J., Zieliński P., Bańbura J.

Polish Journal of Ecology

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2016

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Vol. 64, nr 3

399--408

EN

Urbanization affects the ecological and behavioral traits of various species of animals, including birds.We present results concerning long-term fluctuations in breeding densities of nest-box populations of the Blue Tit Cyanistes caeruleus and the Great Tit Parus major in two, structurally and floristically contrasting types of habitat (an urban parkland and a rich deciduous forest) located 10 km apart, in central Poland. This study was conducted in 1999–2012 in the parkland site and in 2002–2012 in the forest site. We found a strong correlation of year-to-year changes in breeding densities of Great Tits between the parkland site and the forest site and a lack of such a correlation in Blue Tits. Breeding densities of Great Tits were much higher in the parkland than in the forest area every year during the study period. Annual changes in breeding densities were not correlated between the species studied. The North Atlantic Oscillation Index (NAO-winter index) tended to influence the density dynamics of the two bird species in the forest area but not in the parkland area.

6

Population dynamics of the main copepod species in the Gulf of Gdańsk (the southern Baltic Sea) : abundance, biomass and production rates

Musialik-Koszarowska M., Dzierzbicka-Głowacka L., Kalarus M., Lemieszek A., Maruszak P., Żmijewska M. I.

Oceanological and Hydrobiological Studies

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2016

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Vol. 45, No. 2

159--171

EN

The aim of this study was to describe the production biomass and abundance dynamics of the major Baltic calanoid copepods (Acartia spp., Temora longicornis and Pseudocalanus sp.) in the Gulf of Gdańsk (the southern Baltic Sea) during a three-year period from March 2010 to December 2012. the data were collected at six stations located in the western part of the gulf. Acartia spp. was the most abundant taxon throughout the study period. the observed differences in the weighted mean depth for the investigated species were >2 m between nauplii and adults of Acartia spp., >5 m between nauplii and adults of Temora longicornis and 3 m between nauplii and younger copepodites of Pseudocalanus sp. the highest values of the secondary production rates were determined for Acartia spp. − almost 17.55 mg C m-2 d-1 (summer 2011), while Temora longicornis reached 3.80 mg C m-2 d-1 in spring 2010 and Pseudocalanus sp. had the highest secondary production values in summer 2011 − about 1.28 mg C m-2 d-1.

7

Field and Laboratory Studies of the Earthworm Dendrobaena Alpina

Kostecka J., Butt K. R.

Journal of Ecological Engineering

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2015

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Vol. 16, nr 5

213--217

EN

Distribution of Dendrobaena alpina covers the mountainous region of central Europe, where it has a high dominance and frequency index. This work describes data from field studies conducted over two annual cycles in the Bieszczady National Park (BNP), Poland, in different types of beech forest. Densities of this species ranged from 47–231 g·m -2 with associated biomasses of 19–90 g·m -2. Most (66%) were recovered from less than 0.1 m soil depth with a further 28% from up to 0.2 m. Further, the animals were collected alive from Lutowiska, close to the BNP to obtain baseline data on the life history of D. alpina. Mature individuals were kept in isolation and cocoon production monitored on a 2 monthly basis. Immature individuals were kept until they reached maturity, when they were paired, with combined output of cocoons regularly monitored. Cocoons were collected, had their masses determined and were incubated. Hatchability was recorded, as was estimated duration of incubation and growth to maturity. Field-collected adults had a mean mass of 1.4 g and at 15 ºC, these produced an average of 1.83 cocoons·worm -1·month -1. Zero cocoons were produced by further specimens, collected as immature, grown to maturity and maintained in isolation. Recently-matured, paired D. alpina produced an average of 1.65 cocoons·worm -1·month -3. Cocoons had a mean mass of 19 mg. At 15 ºC, cocoons produced by recently matured adults hatched after 80 days (82% viable), but after 2 months the majority of cocoons failed to hatch. Hatchling growth from an average of 18 mg to maturity required 7–11 months in the given substrate.

8

Spatiotemporal variation of drift and upstream movements of the amphipod Gammarus fossarum in a small unaltered stream

Žganec K., Gottsein S., Hudina S.

Polish Journal of Ecology

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2013

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Vol. 61, nr 4

769--784

EN

Stream invertebrates use ‘drift’ or downstream transport in the water column to disperse, but they also actively move upstream against current. These movements have important role in re-colonization of empty stream reaches and in regulation of population size. For more than half a century, research of stream drift was stimulated by the problem of ‘drift paradox’, i.e. the question how upstream reaches of streams remain inhabited despite constant and often ample losses of individuals by drift. In this study we examined drift and upstream movements of the amphipod Gammarus fossarum through monthly sampling over one-year period at two sites in the upper and middle course of a small unaltered stream in the northwest Croatia. Differences in tendency to drift and to move upstream and effects of environmental factors (temperature, flow, population density and detritus dry weight) on the movement dynamics on both temporal and spatial scale were examined for three size categories (adults, subadults and juveniles). While seasonal variations of drift and upstream movements were similar at two examined sites, at the middle course we recorded higher density, and higher drift and upstream movement rates. In both drift and upstream movements, adults were the most represented size category. In subadults and juveniles, both type of movements depended on population density. Adult upstream movements peaked in November and May/June, with massive upstream movements in May in the middle course. Seasonality of diurnal and nocturnal drift was very similar at both sites, while seasonality of diurnal and nocturnal upstream movements differed between the sites. Out of four examined independent environmental factors, density and temperature had the most important positive effect on spatiotemporal variations of diurnal drift, while nocturnal drift was more strongly affected by density and flow. Temperature was the most significant driver of diurnal upstream movements, while nocturnal upstream movements were most significantly positively affected by density. Massive upstream movements were driven by overcrowding and enabled adults to colonize microhabitats where food is more abundant and competition is less severe.

9

Global existence and asymptotic behavior for a nonlinear degenerate SIS model

Ziane T. A.

Opuscula Mathematica

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2013

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Vol. 33, no. 4

615--630

EN

In this paper we investigate the global existence and asymptotic behavior of a reaction diffusion system with degenerate diffusion arising in the modeling and the spatial spread of an epidemic disease.

10

Storage of hydrogenous gas in geological formations: self-organisation methane gas

Toleukhanov A., Kaltayev A., Panfilov M.

AGH Drilling, Oil, Gas

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2013

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Vol. 30, no. 1

241--245

EN

In the case of producing large amounts of hydrogenous gas, currently there are no problems related to basic techniques of hydrogen production and distribution, but the main technological problem will consists of storing it in order to regulate the difference between permanent or increasing gas production and seasonally modulated gas consumption. The most efficient and most inexpensive method of storing large amounts of hydrogen is to inject them in geological formations like aquifers, depleted gas reservoirs, or salt caverns (Zittel and Wurster 1996). The cost is of order $ 3.5 per 1 GJ (Taylor et al. 1986). Several underground storages of hydrogen (USH) or town gas exist in the word, as for instance, Teeside in the UK, in Texas, in Russia, Kiel in Germany, Lobodice in Czechoslovakia, Beynes - an ex-storage in France. During several tens of years the storage of hydrogen was considered as something deja-vu, to be similar to that of natural gas, which is amplified by the chemical inactivity of hydrogen and its very low solvability in groundwater [Bulatov 1979; Carden and Paterson 1979; Lindblom 1985; Paterson 1983]. Nevertheless, quite unusual behaviour of UHS was discovered by in situ monitoring of the gas composition extracted during the cycle "production" which followed the cycle "injection". These observations (Smigai et al. 1990; Buzek et al. 1994) revealed high variations of gas composition in time and space. In particular, a significant reduction in the H2 and CO2 contents and a simultaneous increase in CH4 contents were observed in the Lobodice town gas storage facility (Smigai et al. 1990). Similar phenomena were recorded in Beynes. After several months of injection and storage, at the beginning of the cycle "production" the twofold increase of the methane contents in the reservoir gas and the twofold reduction of the CO2 CO contents was observed. The contents of hydrogen decreased by 1.4. The explanation to these observations has been done in (Buzek et al. 1994) in terms of the in situ methane generators by methanogenic bacteria which catalyse the reaction between hydrogen and CO2/CO, by producing methane and water. Further observations have revealed even more unusual effects within the storage facility, such as creating a spatial alternation of the areas saturated preferably by hydrogen or methane. This proved an in situ natural separation of chemical components in space. Thus, we are dealing with a natural reactor which partially destroys CO2 and H2 and doubles the mass of methane. It is clear that the problem is important for industry as it concerns both the energy sector and ecology. The resulting economical efficiency of such a process can be estimated only after the physical and mathematical modeling of all possible scenarios of the reservoir behaviour. The development of such a model represents the main objective of this paper.

11

Formation and dynamics of the metapopulation of Senecio rivularis (Waldst. & Kit.) DC. (Asteraceae) at the limit of its geographical range : where, when, by what means?

Czarnecka B.

Polish Journal of Ecology

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2011

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Vol. 59, nr 2

263-278

EN

In the studies on the metapopulation system two aspects are important: cognitive and practical. The former indicates that a metapopulation is a demographic structure of a higher level than coenotic or local populations and aims at recognition of relations between particular populations of a given species. The practical aspect reflects the issues of the dynamics and/or the extinction rate in particular populations and indicates potential habitats which can be colonized. The study of the Senecio rivularis metapopulation is created by relatively abundant population of ragwort in the Roztocze Highlands, Roztocze National Park, south-eastern Poland, recognized as the source population and three other called marginal or sink populations as well as potentially suitable habitats which are distributed as islands in adjacent hydrogenic areas. The distances between particular populations range from 1.3 to 6.5 km. As a long-lived, iteroparous rhizomatous clonal plant, insect-pollinated and anemoc anemochoric one, so having adaptations both for 'escape in time' and 'escape in space', S. rivularis may be treated as the model object of the study on the metapopulation level. The following hypotheses were put forward: (1) the spatial pattern, size and life-stage structures of particular populations reflect the time of their origin in the meta-system; (2) hydrochory is a complementary or alternative way of migration of anemochoric diaspores; (3) local watercourses and hydro-technical activity affect the formation and dynamics of S. rivularis metapopulation. The multi-aspect studies of the source population were conducted in the years 1987.2007. They aimed to establish the density, spatial pattern and life-stage structure of the S. rivularis population, both at a large scale, i.e. in the whole population (three times) and at a small scale, i.e. on the level of three particular clumps (four times). The size structure of generative genets and ramets in the whole population was aleborated five times. In the greatest of the other populations in the meta-system, the size structure was elaborated twice (2002, 2007) while the study of spatial and life-stage structures was done only once, in the first period, because of the disturbance of a greater part of the population in the next years. In the two remaining localities all plants were counted thanks to small abundance of the populations. Considerable changes in the spatial organization and life-stage structure of genets in the source and sink populations exhibited that colonization in the meta-system of S. rivularis proceeds in accordance with an island model of the 'stepping stone' type, downstream the river. Renaturalization of water relations of river catchment areas and construction of the so-called small retention objects affect the formation and dynamics of S. rivularis metapopulation which reflects at least some dynamics phases observed at the level of the source population: progressive, stable, fluctuation and/or regressive, and extinction phases. Knowledge of the density, life-stage and size structures of plants in a population facilitates a highly reliable determination of the development phase of a given local population in the meta-system and prognosis of its future.

12

Emigration Acitivity of Rice Weevil Sitophilus oryzae L (Coleoptera, Curculionidae) in Conditions of Reduced Temperature

Kłyś M.

Ecological Chemistry and Engineering. A

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2011

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Vol. 18, nr 5-6

717-721

EN

The subject of the research was rice weevil Sitophilus oryzae L. – dangerous pest of grain crops storage. Research was held in a laboratory at the temperature 31 °C, optimal for this insect species, and reduced to 22 °C, and 70 5 % relative humidity (R.H.). The main research problem concerned the emigration activity of S. oryzae in conditions of temperature reduction. Population dynamics and sex structure of population were also analyzed. It was affirmed that rice weevil shows a very high emigration activity in temperatures both 31 °C and 22 °C. Whereas the temperature reduction to 22 °C causes drop of emigration activity to 40 % only in two time ranges after 60 and 120 days of raise ing. A higher female emigration was also observed.

PL

Obiektem badań był wołek ryżowy Sitophilus oryzae L. - groźny szkodnik magazynowanego ziarna zbóż. Badania prowadzono w laboratorium w temperaturze 31 oC optymalnej dla tego gatunku owada i w obniżonej do 22 oC, oraz w wilgotności względnej powietrza 70 š 5 % r.h. Główny problem badawczy dotyczył aktywności emigracyjnej wołka ryżowego w warunkach obniżonej temperatury. Analizowano także dynamikę liczebności i strukturę płciową populacji S. oryzae. Stwierdzono, że wołek ryżowy wykazuje bardzo dużą aktywność emigracyjną zarówno w temperaturze 31 oC, jak i 22 oC. Obniżenie temperatury do 22 oC powoduje spadek aktywności emigracyjnej do 40 % tylko w dwóch przedziałach czasowych po 60 i 120 dniach prowadzenia hodowli. Zaobserwowano również większą emigrację samic.

13

Effect of light competition with filamentous algae on the population dynamics and development of the moss species Warnstorfia exannulata in a softwater lake

Szmeja J., Bociąg K., Merdalski M.

Polish Journal of Ecology

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2010

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Vol. 58, nr 2

221-230

EN

The effect of a massive bloom of filamentous algae on the long-term abundance dynamics of the moss Warnstorfia exannulata (B., S. & G.) Loeske was studied in an acidic lowproductivity lake in NW Poland. Individuals were counted on 4 experimental plots, 1 x 1 m each, at a depth of 2.5 m. The studies were conducted for 36 months, every 30 days, by SCUBA diving. Over the three years the seasonal changes in water pH, conductivity, HCO3 - concentration, sediment hydration and pH were not statistically significant (P> 0.05), and light intensity was higher in winter than in summer. Over the three years 4 consecutive stages of population development were observed: regeneration, stabilisation of abundance (fluctuations), regression and repeated regeneration. These stages appeared and lasted at different temperatures and light intensity. The greatest monthly increase in abundance took place in summer and lasted until the beginning of autumn under conditions of high temperature and relatively low light intensity. Long-term abundance variations were strongly correlated with the appearance of filamentous algae, less strongly with the dynamics of the dominant species (Sphagnum denticulatum), and the least with water temperature, light intensity, water and sediment pH, conductivity and HCO3 - concentration. As a result of a massive bloom of these algae, light intensity decreased in the water, Warnstorfia shed its leaves, and then the entire population disappeared. In winter that year it began to regenerate from vegetative propagules (leafless shoots), which were the remains of individuals growing before the filamentous algae appeared. In softwater lakes such massive algal blooms are a common phenomenon which limits light transmission to the substrate and as a result leads to changes in the submerged vegetation structure, especially that of bryophytes.

14

Effects of Lowered Temperatures on the Migration Activites of the Grain Weevil Sitophilus granarius L (Coleoptera, Curculionidae)

Kłyś M.

Ecological Chemistry and Engineering. A

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2010

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Vol. 17, nr 10

1349-1354

EN

The subject of our study was the grain weevil Sitophilus granarius L. In this work based on laboratory research, it has been presumed that lowering environment temperatures can have an effect on emigration and immigration processes, and thus on the spread of this pest. The control culture was conducted at a temperature of 28 oC. The environment temperature of the experimental cultures was changed weekly, and consecutively set at: 25 oC, 10 oC, 21 oC and 25 oC. In conditions facilitating the migration of adult S. granarius specimens, the lowered temperature of the surroundings reduced the population’s migration activity, and a particular drop in female migration activity was observed. Females are more sensitive to the effects of lower temperatures.

PL

Obiektem badań był wołek zbożowy Sitophilus granarius L. W badaniach laboratoryjnych przyjęto założenie, że obniżenie temperatury środowiska może wywierać wpływ na procesy emigracji i imigracji, a tym samym na rozprzestrzenianie się tego szkodnika. Hodowle kontrolne prowadzono w temperaturze 28 oC. W hodowlach eksperymentalnych co tydzień zmieniano temperaturę środowiska, stosując kolejno: 25 oC, 10 oC, 21 oC i 25 oC. W warunkach umożliwiających migracje osobnikom dorosłym S. granarius obniżenie temperatury otoczenia spowodowało zmniejszenie aktywności migracyjnej populacji, a szczególnie spadek aktywności migracyjnej samic. Samice są bardziej wrażliwe na oddziaływanie niskich temperatur.

15

Flowering and generative reproduction in isolated populations of endangered species Carlina onopordifolia Bessr (Asteraceae) in Poland

Denisiuk Z., Chmura D., Adamski P.

Polish Journal of Ecology

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2009

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Vol. 57, nr 1

89-97

EN

Carlina onopordifolia is longlived monocarpic perennial plant, which reproduces only generatively, however, it flowers and fruits only once in lifespan (10-20 yrs) and after seeds development it dies. Due to this type of reproduction the abundance of population depends on amount of produced seeds, moreover the plant flowers more abundantly every 2-3 years. The plant is highly specialized in respect to habitat and micro-climate conditions. It grows on calcareous and sun-heated slopes, where xerothermic grasslands grow with contribution of species typical for steppe vegetation. In Poland it is a very rare species known only from seven isolated natural stands in south and east part of the country. Differences and year-to-year fluctuations in the frequency and the abundance of generative and vegetative specimens in natural stands were studied in 2006 and 2007 years. The regional differences in leaf rosette size and size of inflorescences were examined. The abundance of population in all stands increased from ca. 13600 plants in 2006 to ca. 31950 in 2007. The G test revealed significant decrease in frequency of flowering plants vs. barren plants between the years in four of all seven stands. The significant differences in mean diameter of leaf rosettes (45; 49; 52 cm) and mean diameter of anthodium of generative specimens (7.17; 7.74; 8.27 cm) were observed in three the most geographically distinct and the most abundant populations. The mean values of leave rosette (44.20; 49.31 cm) and sizes of anthodiums (6.05; 7.61 cm) also changed significantly between the years 2006 and 2007, respectively for all data. It can be concluded that in all stands of the thistle in Poland the synchronization of blooming phase takes place. The observations implicate conclusions important for practice of monitoring which must be conducted at least for two vegetative seasons covering the whole phenology of the species in order to prevent the artifacts.

16

The dependencies between the abundance of Chironomus f. l. plumosus and bream (Abramis brama) net catches in a lowland reservoir (Zegrzyński Reservoir, central Poland)

Prus P.

Oceanological and Hydrobiological Studies

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2009

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Vol. 38, No.3

15-30

EN

Chironomus f. l. plumosus larvae, a valuable food of bream (Abramis brama (L.)), dominate in the benthos of the extra-littoral zone of the shallow, lowland, eutrophic Zegrzyński Reservoir. Bream is the dominant fish species in this reservoir, making up to 80% of total net catches. During eight years of studies, very regular Chironomus population dynamics were noted in the lotic part of the central, broad basin of the reservoir. There were usually two peaks of the abundance: the higher one in spring, and the much lower one in late summer. Both peaks of Chironomus abundance positively correlated with commercial net catches of bream in the reservoir in particular years. The total bream catch per year in the reservoir studied also correlated positively with the average yearly abundance of Chironomus. The correlation between Chironomus abundance and bream occurrence (measured by commercial net catches) in the reservoir studied suggests that this environment is used by bream mainly as a feeding ground. In the years with a low spring Chironomus peak of abundance, the bream leave the reservoir, searching for food in its inflows - two large, lowland rivers. This corresponds to much lower catches noted in the reservoir in the years of low Chironomus abundance.

17

Parthenogenesis and gamogenesis in seasonal succession of chydorids (Crustacea, Chydoridae) in three low-productive lakes as observed with activity traps

Nevalainen L.

Polish Journal of Ecology

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2008

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Vol. 56, nr 1

85-97

EN

The aim of the present study was to determine the variance in abundance of parthenogenetic (asexual) and gamogenetic (sexual) individuals among chydorids (Crustacea, Anomopoda, Chydoridae). The chydorids were monitored quantitatively with stationary activity traps in three lakes in southern Finland at 2-week intervals during the open-water season (early May-late October) in 2006. The lakes chosen for the study were low-productive forest lakes; Lake Kalatoin was dystrophic fish-free lake and lakes Tuhkuri and Iso Lehmalampi were oligotrophic. The abundance of trapped individuals varied widely among the lakes and during the sampling period presumably due to site-specific environmental conditions (available microhabitats, food, shelter). The abundance was highest in the dystrophic Lake Kalatoin (max. 43 x 10[^3] m[^2] trapday[^-1] in June) and clearly lower in the two oligotrophic lakes (max. 8.5 x 10[^3] m[^-2] trapday[^-1] in Lake Tuhkuri in mid-July and max. 2.2 x 10[^3] m[^-2] trapday[^1] in Lake Iso Lehmalampi in mid-October). The chydorids exhibited unique sexual reproduction patterns among sampling sites and populations as the abundance of trapped gamogenetic individuals differed, suggesting habitat- and population-specific patterns in gamogenesis. In lakes Kalatoin and Iso Lehmalampi gamogenetic individuals were caught in the traps during the autumn with maxima of 2.2 and 1.6 x 10[^3] m[^-2] trapday[^-1], respectively, but in Lake Tuhkuri no gamogenetic individuals were encountered during the autumn. Although Alonella nana (Baird) was most abundantly trapped species in all the lakes, its gamogenetic individuals were trapped numerously only in Lake Kalatoin (max. ca. 1.5 x l0[^3] m[^-2] trapday[^-1]). The results suggest that gamogenesis in chydorids is a more complex phenomenon than previously believed.

18

A Predator-Prey Cellular Automaton with Parasitic Interactions and Environmental Effects

Farina F., Dennunzio A.

Fundamenta Informaticae

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2008

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Vol. 83, nr 4

337-353

EN

We propose a lattice model to describe a predator-prey system where two species with significantly different size are considered. The biological analogy we refer to is the predatory interaction between bacteria and viruses. We assume simple environmental effects altering the dynamics. Preys (bacteria) procreate by mitosis and they do not move. They may die because of natural causes or under the predation. The predation is the consequence of a diffusive phenomenon by the predators (viruses). Predators grow in number by infection and by prey self-immunity diseases, and they die by starvation.

19

Temperature influence at the feeding activity of lesser grain borer Rhyzoperlha dominica F. (Coleoptera, Bostrichidae)

Kłyś M.

Ecological Chemistry and Engineering. A

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2008

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Vol. 15, nr 4-5

355-360

EN

The aim of the research was the lesser grain borer Rhyzopertha dominica F., a dangerous pest of stored wheat grain and foodstuffs. As the first pest biting the grain, the lesser grain borer helps many other species to attack the grain. The aim of laboratory experiments was to study how various temperature affects feeding activity of this species and an investigation of birth rate dynamics and mortality of the population. Experiments were conducted in three temperature variants: 28, 22 and 31°C. Regular tests were done concerning the proportion of food (wheat grain) consumed, its contamination and the rates of consumption by experimental populations. It was concluded that temperature exerts an influence on the population development as well as on its feeding activity. The decrease in temperature to 22 °C is considered as a factor which inhibits the population development of R. dominica. On the other band, at 31°C, consumption is the highest. Besides that, during the whole experimental period, the degree of grain damage was higher than consumption in all of the studied temperatures, which provides evidence of a high feeding activity of this species.

PL

Obiektem badań był kapturnik zbożowiec Rhyzopertha dominica F. - groźny szkodnik magazynowanego ziarna zbóż i produktów spożywczych. Jako szkodnik pierwotny, nadgryzając ziarno, ułatwia jego atakowanie wielu innym gatunkom. Celem badań laboratoryjnych było zbadanie wpływu różnych temperatur na aktywność pokarmową tego gatunku oraz zbadanie dynamiki liczebności i śmiertelności populacji. Eksperymenty prowadzono w temperaturze 28, 22 i 31°C. Regularnej kontroli poddawano stopień zużycia pokarmu (pszenicy), jego zanieczyszczenie oraz konsumpcję populacji. Stwierdzono, że temperatura wywiera wpływ zarówno na rozwój populacji, jak i na jej aktywność pokarmową. Obniżona temperatura (22 °C) jest czynnikiem hamującym rozwój populacji R. dominica. Natomiast w temperaturze 31°C konsumpcja jest największa. Poza tym w ciągu całego okresu badawczego stopień uszkodzenia ziarna przewyższa konsumpcję we wszystkich badanych temperaturach, co świadczy o dużej aktywności pokarmowej tego gatunku.

20

Effect of increased temperatures on the population dynamics of saw-toothed grain beetles Oryzaephilus surinamensis L (Coleoptera, Cucujidae)

Kłyś M.

Ecological Chemistry and Engineering. A

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2008

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Vol. 15, nr 1-2

75-80

EN

The study included the saw-toothed grain beetles Oryzaephilus surinamensis L. kept in stores and granaries. The aim of the laboratory experiments was to analyse the effect of the short-termed and periodically increased temperatures on the population dynamics of this species. The control and experimenta1 cultures were kept in a thermostat at a temperature of 30°C and relative humidity (r.h.) of 70 %. Semolina was used as a substrate in all the cultures. In the first variant of the experiments, seven days before the assessment the cultures were exposed to a short-termed effect (0.5 h) of the temperature increased to 35°C. In the second variant, the cultures were exposed to the effect of the temperature increased to 35°C in the same way, but for 24 hours. It was found out that the increase in temperature, both short-term and periodical causes a decrease of a population size. The elevated temperature, especially lasting for 24 hours also causes an increase of the population morta1ity. Moreover, it was found out that the females are more sensitive to the effect of temperature rises.

PL

Badaniami objęto spichrzela surynamskiego Oryzaephilus surinamensis L. - owada żyjącego w produktach zbożowych przechowywanych w magazynach i spichlerzach. Celem badań laboratoryjnych była analiza wpływu krótkotrwałego i okresowego działania podwyższonych temperatur na przebieg procesów populacyjnych tego gatunku. Hodowle kontrolne i eksperymentalne prowadzono w termostacie w temperaturze 30°C i wilgotności względnej 70 %. Jako substrat we wszystkich hodowlach zastosowano kaszę mannę. W pierwszym wariancie eksperymentu hodowle co cztery tygodnie, siedem dni przed terminem kontroli, poddawano krótkotrwałemu (0,5 godz.) oddziaływaniu podwyższonej do 35°C temperatury. W drugim wariancie eksperymentu hodowle poddawano w taki sam sposób oddziaływaniu temperatury podwyższonej do 35°C, ale przez okres 24 godzin. Stwierdzono, że podwyższenie temperatury zarówno krótkotrwałe, jak i okresowe powoduje zmniejszenie liczebności populacji. Podwyższona temperatura, zwłaszcza działająca przez okresy 24-godzinne powoduje także wzrost śmiertelności populacji. Ponadto stwierdzono, że samice są bardziej wrażliwe na podwyższanie temperatury.