A crucial factor affecting the rate of eutrophication is the characteristics of the catchment area of lakes. The most visible result of excessive eutrophication is rapidly deteriorating transparency of waters in the summer which is caused by rapid development of planktonic algae. Another symptom of this process is gradual overgrowth of water reservoirs and watercourses by macrophytes. Hence, in order to improve the quality of water in these lakes the renovation treatment is applied. Lakes restoration can be made in many ways: physical, chemical and biological. The chemical and physical methods of lakes restoration are invasive and controversial. However, one of the relatively not invasive methods of lakes restoration is ecological biomanipulation. The goal of biomanipulation is to reduce the concentration of harmful phytoplankton, by the stocking of predatory fish triggers a trophic cascade with decreases in the biomass of smaller-bodied fish, e.g. cyprinids, increases in the biomass of herbivorous zooplankton, and decreases in the biomass of harmful phytoplankton. In some cases plankton-eating fish have been removed directly by lake managers. In addition, the removal of bottom-feeding fish from shallow lakes leads to increases in rooted vegetation and increased water clarity as the rooted plants stabilize the sediments. This transition involves a trophic cascade, as herbivorous zooplankton increase in biomass and consume phytoplankton, but also involves the direct effects of rooted vegetation on sediment stability and nutrient cycling. The most frequent cause of fast eutrophication is the runoff of untreated sewage directly into the waters of lakes and rivers or the excessive runoff of biogenic compounds from agricultural catchment areas. Forest lakes because of far distance from agglomeration and agricultural areas are in lesser extent exposed on the human pressure. Generally, one unfavorable variable affected these lakes is angling pressure. Thus, due to the lack of pollution and the relative stabilization of the mid-forest lakes they are a good place to conduct the ecological biomanipulation. The aim of the present study was to determine the short-term biomanipulation effectiveness in three shallow forest lakes. Biomanipulation was performed by stocking in 2012 to these lakes a summer fry of pike (200 ind. ha-1) and zander (150 ind. ha-1). Before the biomanipulation (in 2011) a control study of physic-chemical parameters, ichthyofauna and zooplankton composition were made. After the biomanipulation (in 2014) the same control study were conducted. Before and after the biomanipulation period significant changes in values of physic-chemical variables were not observed. Similarly, a slight changes in ichthyofauna composition between these two period occurred. The roach and bream were the biomass dominants. Only the zooplankton composition obtained pronounced changes, but statistically not significant. The most visible differences in zooplankton abundance concerned cladocerans – group that the most affect the phytoplankton decreasing. After the biomanipulation abundance of cladocerans increased from 31% to 67%. According to the results, it can be concluded that the biomanipulation time in study lakes was too short to make significant changes. To get a better effect of biomanipulation a successive stocking with summer or autumn fry of pike and zander should be conducted, even in 1000 ind. ha-1. Finally, we can assume that in the forest, shallow, highly eutrophic lakes a biomanipulation with predatory fish may be sufficient for their effective restoration.
Bodies of water are very sensitive to environmental changes and play an important role in nutrient cycle in their catchment. Due to their natural features such as reduction of the land fill, they may cumulate organic matter from the catchment. Excess supply of nutrients to water bodies contributes to gradual water eutrophication. This process can occur rapidly, particularly in shallow lakes, which are more susceptible to degradation. This also results in deterioration of habitat conditions for many organisms and limits the economic use of water. Eutrophication may lead to gradual shallowing and shrinkage of water bodies, and, consequently, to disappearance of lakes. Thus, proper diagnosis and reduction in the amount of pollutants flowing into lakes are key factors to improve water quality and prevent their further degradation. Lake Głęboczek, like many other urban lakes year were powered by sewage. As a result, the tank has ceased to be an attractive element of urbanized land, and became the object of nuisance for residents, often acting health risks. For this reason, the lake has undergone numerous Głęboczek reclamation treatment and protection. The object of this study was rehabilitated water from the lake Głęboczek in Tuchola. Samples were taken 12-fold in 3 places during the period from March 2011 to February 2012. In the tested water was determined by the colorimetric method phosphorus, phosphate, nitrogen, nitrate, nitrite, and aluminum. Additionally, the pH and temperature. Lake Głęboczek is a reservoir, which is heavily influenced by human activities, direct and indirect. This is due to the central location of the water, the entire drainage area is densely populated and intensively exploited for agricultural purposes. One of the most important elements harboring an increase in trophic status of the lake, is its low average depth. In addition to the lake Głęboczek not affect any river, which prevents water exchange and causes the accumulation of pollutants. Both the results of their own and other authors suggest that the degree of eutrophication of the lake Głęboczek apparently decreased. The level of biogenic elements and their compounds was higher than the results obtained in 2001 (after restoration), which may indicate improper sewage and agricultural economy in the catchment of the lake. Oversize nutrient content indicate a renewed increase in trophic lake.
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The experiment was established in a set of containers. Every container held a 10 cm thick layer of profundal sediments and water from a badly polluted lake. The following five preparations were tested (brand names): AQUAKALGON+, BIOGEN REMEDIANT, BIODENN K, ECOTABS 1(TABLETS), ECOTABS 2(POWDER). The biological preparations were applied twice: phase I lasted 56 days and phase II was continued for 21 days. The research results demonstrated that considerably higher values, compared to the control, were initially (day 3) obtained for TOC after the application of ECOTABS 1, for total nitrogen − after BIODENN K and ECOTABS 1, and for total phosphorus − after BIODENN K, ECOTABS 1 and BIOGEN REMEDIANT. Multiplying bacteria might have been an additional source of organic matter in water, which was subsequently deposited in the bottom sediments as implicated by a higher percentage (by 1 to 7% of d.w.) of organic matter in the sediments at the termination of the experiment. Our preliminary experiment did not provide any justification for using the tested preparations in lake restoration efforts. Subsequent studies should focus on the question whether mineral phosphorus released to the lake water or a drastic change in the environmental conditions would not lead towards the dominance of invasive and highly toxic cyanobacteria.
Nitrogen related water pollution in aquatic systems is one of the most common problems encountered worldwide nowadays. Different restoration practices have been tested to eliminate the impacts from eutrophication but no widely applicable methodology has been found until now. Extract of Yucca shidigera has been proved effective in reducing ammonia in livestock industry and aquaculture but have not been yet tested in freshwater ecosystems. In this study, the effects of yucca extract on the reduction of ammonia in Lake Koumoundourou have been investigated. Yucca extract was added at various concentrations to experimental tanks containing lake water and sediment. The results show that yucca extract significantly reduced the concentration of ammonia while other water quality parameters were relatively stable during the experiment, except from dissolved oxygen. The study indicates that yucca extract as a restoration method can be promising but larger scale experiments should be conducted to validate this outcome.
The restoration of the anthropogenic Pławniowice water reservoir with the hypolimnion withdrawal method (the Olszewski's tube) began in December 2003. The decision to restore the reservoir had been taken due to its terrible condition resulting from the hypertrophy, which had been indicated by the research from the years 1993–1998. The following paper presents the results of eight-year-long research into the formation of oxygen conditions and restoration settings. They were compared with the data obtained from the research before the restoration. Positive changes were witnessed. It was showed that grasping the changes in oxygen conditions enables the comparison of oxygen profiles in the same months in subsequent years. The ratio of anoxic water layer thickness to the oxygenated layer thickness was suggested as a factor characterizing oxygen conditions. The area described with an izooxa in the xy coordinate system was suggested as a factor [O2 mg/m2] allowing researchers to understand and describe occurring changes. It was observed that the oxygen solved in water as a result of the restoration occurred in the whole water column in the third decade of July. The oxygen concentration in the hypolimnion gradually rose in May, June and July each year. It was showed that the improvement in oxygen conditions stemmed from progressing oligotrophy of the reservoir.
PL
W grudniu 2003 roku rozpoczęto rekultywację antropogenicznego zbiornika wodnego Pławniowice metodą usuwania hypolimnionu („rura Olszewskiego”). Decyzja o rekultywacji została podjęta w związku z dramatyczną sytuacją zbiornika wynikającą z jego hipertrofii, co wykazały badania z lat 1993–1998. W niniejszym opracowaniu przedstawiono wyniki ośmioletnich badań nad kształtowaniem się stosunków tlenowych, warunkach rekultywacji. Wyniki te porównano z danymi uzyskanymi w trakcie badań przed rekultywacją, wykazując pozytywne zmiany. Wykazano, że uchwycenie zmian stosunków tlenowych umożliwia porównywanie profili tlenowych w tych samych miesiącach, w kolejnych, następujących po sobie latach. Zaproponowano stosunek miąższości warstwy wody pozbawionej tlenu do miąższości warstwy natlenowanej, jako wskaźnik charakteryzujący warunki tlenowe. Zaproponowano pole powierzchni określone izooksą w układzie osi (x, y) jako wskaźnik [mg O2/m2] umożliwiający uchwycenie i opisanie zachodzących zmian. Stwierdzono, że w wyniku rekultywacji rozpuszczony w wodzie tlen występuje w całym słupie wody jeszcze w trzeciej dekadzie lipca. Z roku na rok stężenie tlenu w hypolimnionie, w maju, czerwcu i lipcu z roku na rok stopniowo wzrasta. Wykazano, że poprawa stosunków tlenowych wynika z postępującej oligotrofizacji zbiornika.
The eutrophication of freshwaters – including shallow lakes – has become a global problem in the 21st century. Cyanobacterial blooms belong to the most frequent effects of this phenomenon. Although the problem, as well as methods for control it, are known since the beginning of the last century, in the last 25 years we can observe an increasing number of publications concerning methods of bloom control. The paper gives a review of different methods (chemical, physical and biological) applied in cyanobacterial bloom control in shallow lake ecosystems, taking into account not only the effectiveness of the methods but also their impact on other water biocenoses.
PL
Jednym z globalnych problemów XXI w. jest eutrofizacja wód śródlądowych, w tym płytkich jezior, której częstym efektem są zakwity cyjanobakterii planktonowych. Problem zakwitów sinic znany jest co najmniej od początku poprzedniego stulecia, podobnie jak i sposoby walki z tym negatywnym zjawiskiem, jednak to w ciągu ostatnich 25 lat, wraz z rozwojem ekologii płytkich jezior, daje się zauważyć wzrost liczby publikacji na temat nowych metod kontroli zakwitów. W artykule przedstawiono przegląd różnorodnych (chemicznych, fizycznych i biologicznych), aktualnie stosowanych metod ograniczania nadmiernego rozwoju cyjanobakterii w płytkich zbiornikach wodnych uwzględniając zarówno ich skuteczność, jak i wpływ na inne biocenozy wodne.
W pracy przedstawiono wyniki badań ilości i jakości wód powierzchniowych dopływających do Jeziora Zdworskiego, prowadzonych w półroczu zimowym roku hydrologicznego 2010. Celem badań, realizowanych od 2007 roku, jest rozpoznanie warunków zasilania jeziora wodami rzeki Wielka Struga oraz jego obciążenia biogenami, a także ocena efektów dotychczasowych zabiegów rekultywacyjnych, obejmujących przeciwdziałanie eutrofizacji jeziora oraz odbudowę jego zasobów wodnych. Prowadzone analizy wykazały, że w półroczu zimowym 2010 roku sytuacja hydrologiczna w Jeziorze Zdworskim i jego zlewni była korzystna: przez większą część tego okresu stan wody w zbiorniku przewyższał stan normalny. W okresie zimowym jezioro zasiliło łącznie 1631,9 * 103 m3 wody, a więc około dwukrotnie więcej niż w latach 2008-2009, przy czym sztuczne zasilanie stanowiło jedynie 14 % tej ilości. Odnotowano także większą niż obserwowaną dotychczas w okresach zimowych dostawę azotu i fosforu, spowodowaną zwiększonym dopływem wody oraz istotnym wzrostem zawartości związków azotu w wodach zasilających jezioro. Pomimo stosunkowo dużej objętości wody dopływającej do Jeziora Zdworskiego, warunki wymiany wód w jeziorze były niekorzystne – w ciągu półrocza zimowego 2010 roku odpływ z jeziora stanowił 7,5 % objętości dopływu. Jednocześnie obciążenie jeziora ładunkiem azotu i fosforu było bardzo wysokie, ponieważ biogeny te znacząco przekraczały ładunek niebezpieczny: w przypadku azotu aż 23-krotnie, zaś fosforu 4,2- krotnie.
EN
Results of quantitative and qualitative assessment of water resources in the Zdworskie Lake catchment area are presented and discussed in this paper. Data collected in the winter season of the hydrological year 2010 were used. Measurement and analysis of water resources in the Zdworskie Lake and its basin have been carried out since 2007 in order to recognize water supply of the lake and nutrients loads discharged into this reservoir and to evaluate effects of the restoration measures. Studies revealed that hydrological condition of the lake during winter season 2010 was good: water level of the reservoir was higher than the normal water level most of the time. Total water supply of the lake in this period (1631,9 * 103 m3 ) was two times bigger than in last two hydrological years. In spite of huge amount of water inflowing into the lake, water exchange in the lake was still very low (7,5%). At the same time increase of nutrients loads discharged into the lake due to poor quality of the main tributary (Wielka Struga river) was observed. Total nitrogen and phosphorus loads exceeded the calculated excessive loads 23 times (nitrogen) and 4.3 times (phosphorus).
The research was conducted in a relatively small (26.8 ha) but quite deep (17.3 m) Lake Długie in Olsztyn, Poland. For over 20 years the lake was collecting sewage which eventually caused its complete degradation. In 1987-2000 the lake was restored using the artificial aeration method with destratification of water. The results showed that the artificial aeration effectively limited the internal loading. Application of this restoration method resulted in reduction of phosphorus compounds concentrations in the analyzed water strata. The decrease of TP in bottom sediments (to the level of 3-4 mg P g1 DW) was probably associated with the fact that a new layer of sediments was created, reflecting a change in the aquatic conditions caused by the restoration. The investigations conducted in the reference years showed that the changes were not permanent. A high concentration of phosphorus compounds in bottom sediments, low sorptive capacity and a tendency to oxygen deficiency, indicate that further possibility to decrease the amount of phosphorus compounds in the lake by this restoration method is limited.
PL
Badania prowadzono na małym (26,8 ha), lecz dość głębokim (17,3 m) Jeziorze Długim w Olsztynie. Przez ponad 20 lat jezioro było odbiornikiem ścieków, co doprowadziło do jego całkowitej degradacji. W latach 1987-2000 zbiornik był rekultywowany metodą sztucznego napowietrzania z destratyfikacją. Uzyskane wyniki badań pokazały, że sztuczne napowietrzanie skutecznie ogranicza zasilanie wewnętrzne. Zastosowanie tej metody rekultywaeyjnej poskutkowało obniżeniem stężeń związków fosforu w badanych warstwach wód. Obniżenie zawartości fosforu ogólnego w osadach dennych (do poziomu 3-4 mg P g1 s.m.) było prawdopodobnie związane z odłożeniem się nowej warstwy osadów, odzwierciedlającej zmienione przez rekultywację warunki środowiskowe w jeziorze. Badania przeprowadzone w latach kontrolnych pokazały, że zanotowane zmiany nic miały charakteru trwałego. Wysokie zawartości związków fosforu w osadach, niska pojemność sorpcyjna i tendencje do wyczerpywania tlenu w warstwach przydennych oznaczają, że możliwości dalszego obniżenia ilości związków fosforu w jeziorze za pomocą tej metody są ograniczone.
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Already in the earliest days of limnology, with regional limnology as the main field of research, it was quite clear that lake ecosystems reflect the character of their catchment areas. At the same time, paleolimnological studies proved that it is possible -by means of stratigraphic and fossil analyses of sediment -to reconstruct the ecological development of both the individual lake and its surroundings. The simple fact that surface water and groundwater are carriers of solid and dissolved matter from catchment to lakes means that the shoreline should not be looked upon as a line of demarcation, but as a zone connecting terrestrial and aquatic ecosystems. A lake together with its catchment area constitutes, there fore, the primary ecological and management unit of a river basin. Water bodies are the mirrors in which the original state - and recent care, management and mismanagement -of the catchments are reflected.
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