ABSTRACTS of the 21 st Conference of Polish Hydrobiologists Lublin, 9-11 September 2009 Organisers: The Faculty of General Ecology at Lublin University of Life Sciences The Faculty of Hydrobiology at Lublin University of Life Sciences The Faculty of Hydrobiology & Botany at the John Paul II Catholic University of Lublin Polish Hydrobiological Society Polish Academy of Sciences, Branch in Lublin Contributions compiled by: Ryszard Kornijów Monika Tarkowska-Kukuryk Wojciech Pęczuła Małgorzata Adamczuk 1
Scientific Committee: Chair: Lublin Members: prof. dr hab. Ryszard Kornijów - University of Life Sciences in dr Paweł Buczyński - Maria Curie-Skłodowska University in Lublin dr Danuta Krupa - University of Life Sciences in Lublin dr hab. Bogdan Lorens - Maria Curie-Skłodowska University in Lublin prof. dr hab. Zdzisław Michalczyk - Maria Curie-Skłodowska University in Lublin dr Tomasz Mieczan - University of Life Sciences in Lublin mgr Marek Nieoczym - University of Life Sciences in Lublin prof. dr hab. Barbara Pawlik-Skowrońska - University of Life Sciences in Lublin prof. dr hab. Marcin Pliński University of Gdansk dr Robert Stryjecki - University of Life Sciences in Lublin prof. dr hab. Władysława Wojciechowska - The John Paul II Catholic University of Lublin Organizing Committee: Chair: Lublin Secretary: Members: dr hab. Krzysztof Czernaś, prof. University of Life Sciences in dr Monika Tarkowska-Kukuryk - University of Life Sciences in Lublin dr Barbara Banach - University of Life Sciences in Lublin mgr Radosław Mencfel - The John Paul II Catholic University of Lublin dr Małgorzata Adamczuk - University of Life Sciences in Lublin dr Wojciech Pęczuła - University of Life Sciences in Lublin dr Michał Solis - The John Paul II Catholic University of Lublin dr Artur Serafin - University of Life Sciences in Lublin dr Agnieszka Szczurowska - University of Life Sciences in Lublin mgr Michał Niedźwiecki mgr Michał Blicharz 2
Introduction This is the first time, when contributions presented during the Conference of Polish Hydrobiologists, organized every three years, are presented in English. Our aim was to enable foreign hydrobiologists to have an insight and overview on the investigations carried out in aquatic ecosystems, mostly by Polish hydrobiologists, although, there were also lectures presented by participants from abroad. The topics presented during the conference comprised nearly all the problems dealing with hydrogenic habitats, such as: hydrology, monitoring, assessment of ecological status, degradation and restoration, biological diversity and invasions, life strategies and evolutionary ecology, interactions, ecotoxycology, paleolimnology, ichthybiology and fishery. Finally, because the conference took place during the Darwinian Year, there were several lectures, given by prominent foreign and Polish scientists, showing achievements of world hydrobiology in creative developing of the Darwin s ideas. The session devoted to this was called Darwinian thinking in limnology, and was inspired and organized with an assistance of Biology Faculty of University of Warsaw. Ryszard Kornijów, Chair of the Scientific Committee Wojciech Pęczuła, Member of Organizing Committee 3
Abstracts Plenary Lectures WHAT CAN FISH-FREE HABITATS TELL US ABOUT THE ROLE OF FISH IN SHAPING OFFSHORE ECOSYSTEMS? Z. MACIEJ GLIWICZ Department of Hydrobiology, Faculty of Biology University of Warsaw Banacha 2, 02-097 Warszawa email: gliwicz@hydro.biol.uw.edu.pl Most fish, at least as juveniles, are planktivores predator-harvesters rather than predator-hunters capable of demolishing planktonic prey populations; a single small roach or sardine may ingest 3600 cladocerans per hour! To optimize its feeding, an individual fish selects large- over small-bodied prey because they are more conspicuous and can be seen from a greater distance (in a wider field of vision), and are energetically more rewarding. This highly selective fish predation results in spectacular changes in the relative abundance of different species in the zooplankton community and of different instars in each species population. The effects of this behavior cascade down to the lower trophic levels, causing alterations in the composition and abundance of algae, protozoans, cyanobacteria and bacteria, ultimately producing marked changes in the turbidity and transparency of the aquatic habitat. For years, efforts have been made to apply this knowledge in eutrophication control and water quality protection by optimizing fishery management, promoting piscivores, and sponsoring the mass exploitation of small cyprinid fish of no commercial value. Gaps in our knowledge have made it difficult to fully appreciate the importance of fish in shaping plankton community structure and the abundance of each species in our lakes and seas. Only recently have we begun to comprehend the mechanisms that lead to fixed proportions of different species in a zooplankton community and of different instars in the populations of each component species. Wide-ranging studies on zooplankton have started to tackle previously unanswered questions such as (i) why is each species population density inversely related to its specific reaction distance (the distance from which a foraging fish can see its planktonic prey), (ii) why is the population density level of each species not dependent on the reproduction rate in populations grown at different food levels, and (iii) why is increased recruitment into the population immediately compensated by increased 4
mortality due to predation by foraging fish? It is now clear that fish predation is the key factor permitting long lasting coexistence of different species with overlapping diets, a phenomenon known as the paradox of plankton, which contradicts the rule of competitive exclusion. Although less intuitive, it is also the case that fish predation is the reason for the high species diversity of zooplankton. The overpowering force of fish predation becomes easier to grasp by examining the consequences of its absence. In rare fish-free habitats, competitively inferior zooplankton species are excluded and replaced by a superior competitor. This may be a single species or a single clone of large body size, e.g. a cladoceran such as Daphnia pulicaria, or a branchiopod such as Artemia franciscana, each capable of building its population to a density orders of magnitude higher than those seen in habitats containing fish. Greater body size permits body growth and reproduction at lower foods levels than those required by smaller and competitively inferior species. The population density of a superior competitor may increase up to the carrying capacity of the habitat, at which point each individual can merely cover its respiration (R) by assimilation (A) restricted by low food levels, with some increase in body mass (P=A-R). This cannot be accomplished by individuals of another species of smaller body size since its specific food threshold concentration at which A=R is higher. This also implies long periods of persistence of adults in the winner s population. These animals are either unable to accumulate sufficient resources or are prudent enough to refrain from egg production, being maladaptive at food levels below their specific threshold food concentration (higher than that specific for adults). Severe competition for limiting resources imposes strong selective pressure for the postponement of reproduction until food levels are temporarily increased. Offspring can only survive when born in a short time window between such an increase in food levels and its subsequent decline resulting from population growth due to the appearance of other juveniles. Such zooplankton become not only a single-species community, but also form a single-cohort long-lifespan population. Do these observations permit any new notions relevant to water quality control and fishery management? This question is intended to close my lecture and to invite members of the audience to come up with new ideas to replace those implemented since the concept of biomanipulation was first introduced. Novel thinking and inspiration are needed to rejuvenate our discipline and reverse the trend of declining interest in fundamental limnology. 5
HOW TO COUNT FISH IN THE LAKE FOR THE WATER FRAMEWORK DIRECTIVE- EXAMPLE OF SHALLOW MALTA RESERVOIR MAŁGORZATA GODLEWSKA, WIESŁAW WIŚNIEWOLSKI Inland Fisheries Institute, Oczapowskiego 10, 10-719 Olsztyn, Poland, e-mail: margogod@wp.pl Hydroacoustic methods are being increasingly used for both fisheries and ecological studies. While usefulness of these methods in deep waters is unquestionable, their accuracy in shallow waters is often doubted. Draining of the shallow Malta reservoir (Poland) provided an unique opportunity to check the accuracy of acoustical estimates of fish stock. Before the draining detailed investigations of the fish population were performed using standard gillnetting and horizontally directed echosounder (split beam Simrad EY500, 120 khz). During reservoir draining all fish were collected and weighted. Roach (Rutilus rutilus) and perch (Perca fluviatilis) were dominating species both in numbers and weight. All together 11 fish species were caught of total weight equal to 34 348,9 kg that is 536,7 kgha -1. Fish biomass estimated acoustically under assumption that fish are distributed with random aspect relative to the beam (i.e. using deconvolution) and using Frouzova et al.[2005] regression for TS/length relationship accounted to 548 kgha -1, which is surprisingly close to the density estimated from the total catch. It has been shown that the TS/length relationship has major effect on fish biomass estimation, while different methods (i.e. based on SED or tracked fish) give very similar results. THE INFLUENCE OF DAM-RESERVOIRS ON RIVER WATER QUALITY RYSZARD GOŁDYN Department of Water protection, Faculty of Biology, Adam Mickiewicz Uniwersity in Poznań, Umultowska 89, 61-614 Poznań, Poland, e-mail: rgold@amu.edu.pl Location of the dam-reservoir on a river course causes distinct disturbances in the processes taking place along its course, described in the theory of river continuum. According to the trophic state indexes it elucidated the decreasing of nutrient concentrations, mostly in the result of processes of primary production and sedimentation of suspended matter, both of allo- and autochthonous origin. It is the reason of popular opinion that every damreservoir can be treated as a panacea on nutrient decreasing in the river course. It was frequently putted into practice in construction so-called preliminary 6
reservoirs, for the protection of situated down-stream main reservoir against the inflow of excessive nutrient loads. In the reality problem is far more complicated. The ability of nutrient retention in a reservoir is dependent on many variables, e.g. on its size and depths, its age, water retention time, nutrient concentration in the inflowing water. They are overlapped by the biological processes, taking place in the reservoir, which are seasonally variable. As the effect preliminary reservoirs can be in some conditions (e.g. in certain periods of their age, or in some seasons of a year) an important source of nutrient loads. It influences the trophic conditions, stimulating water blooms in main reservoir situated down-stream. BIOLOGICAL INVASIONS OR COMMING BACK HOME? MICHAŁ GRABOWSKI, KAROLINA BĄCELA-SPYCHALSKA Institute of Biogeography and Ecology of Invertebrates, University of Lodz, Banacha 12/16, 90-237, Lodz e-mail: michalg@biol.uni.lodz.pl In the last century biological invasions are treated as the biggest danger for native biodiversity. Human activity undoubtly influence the intensive expansion of plants and animals. Connections of different catchment areas by construction of inland canals, intensive boat transport and aquacultures resulted in exchange of fauna among areas previously isolated. The alien species, which colonised new territories very rapidly and serve a danger for natives is called invasive species. The European fauna is relatively young and has been forming for 11,000 years, after the glacial age (Würm glaciation) finished. The Iberian, Apennine, Balkan peninsulas and Ponto-Caspian region served as refugia for many animal and plant species during Pleistocene ice age. In many cases the recolonisation of Europe started from these areas. The brown bear, hedgehog, green grasshopper and fresh water chub, barbel and European bullhead are the well studied examples of recolonisation of Europe from southern refugia. Therefore, question arise if species as zebra musell, Chelicorophium curvispinum or racer goby, which spread out from Ponto-Caspian region, are alien elements in fauna of Central and Western Europe or maybe they are coming back to areas inhabited before ice age, but with a human help. May we treat as an alien the gammarid of Balkan origin Gammarus roeselii which has been noticed in our rivers for longer than 100 years, or maybe its presence in Central and Western Europe is an effect of recolonisation? Concerning that one can ask if the idea of diminishing the invasive species population size is right. The main aim of all activities in invasive species management is protection of native biological diversity. However, may we state undoubtly what is native 7
and what not in particular area in the light of historical human mobility and ability to environment modifications? We need to keep in mind that for example Suez Canal was constructed in ancient ages and had been working till 6 century C.E. and the exchange of goods was well developed on the continental and intercontinental scale during ancient and Middle Ages. Concerning the above the problem of defining what is alien, invasive and native species occur. Can be native species invasive, when it recolonises very extensively areas inhabited before after declining geographical borders? Can be the species called native when it was introduced successfully long time ago and still is present in the area? And the most important question: which species should be protected? PALEOLIMINOLOGIC RESERCH METHODS APPLICATIONS, POSSIBILITIES AND LIMITATIONS. KRYSTYJNA MILECKA Department of Biogeography and Paleoecology Adam Mickiewicz University, Dzięgielowa St. 27, 61-680 Poznań, milecka@amu.edu.pl In regard of an abrupt quickening of a civilization development during the last few decades, actions related with preservation of environment have become a necessary aspect accompanying the economic growth. They are essential to achieve conservation of some ecosystems and species, especially those threatened of anthropopression due to specific ecological requirements and specific conditions of existence. Peatbogs and lakes doubtlessly belong to this group, especially those of a low nutrient content i.e. oligotrophic. Their number and/or area diminishes in consequence of conscious human s actions tending to agronomical land cultivation of some areas, and also unintentional effects of e.g. eutrophication processes inseparably connected to intensification of industrial and agricultural production. Nature preservation is very closely related to paleoecological research and paleolimnology, because only studying the natural past allows effective elaboration of proper conservation methods. The condition of ecosystems, which we observe nowadays is only a short period in several hundred years, or usually longer, history. Studying the conditions affecting on the one hand formation of a given configuration, on the other assuming a present form has a key meaning for a strategy of effective conservation actions. Lakes past researches use methods connected to identification of not decomposed animal and plant elements, lying in organic sediments, usually gyttja and peat. 8
Plant and animal micro- or macrofossils such as: pollen grains, seeds, fruits, flower and seed scales, bark or wood fragments, diatoma skeletons, cladoceran shells, malacofauna, fragments of insects and numerous groups of organisms allow to reconstruct flora and fauna existing in the past time horizon. The condition of their usage is the ability of separating of particular remains and - above all - their identification. Remains in a fossil state are sometimes a little different than a fresh/young, or present-days specimen. Numerical and qualitative comparison of a determined organism s fragments are the basis of a paleoliminologic (paleoecologic) interpretation, during of which the knowledge about ecology of a given species is used. Interpretation of a paleobiological work s results is an intimately linked to a problem of an organic sediments dating or a direct notation of an age of a selected remains. Paleolimnologic analysis has a various applications in research of formation and development of lake body, trophy changes and particular physico-chemical features of waters (e.g. temperature, ph), but also water level fluctuations and filling in the lakes by accumulation the limnic and peat sediments, leading to complete fulfillment of an accumulative basin and origin of a land ecosystem. The sediment s elements analysis allows the reconstruction of a history not only the mother configuration of their deposition, but also surrounding the lake land communities, therein forest. Another, wide and vital aspect of paleolimnoligic researches is observing the anthropopression precisely recorded in accumulated layers from feebly illustrated changes in Mesolithic, till drastic environmental changes of the 20 th century. Applications of paleolimnologic research in mentioned and many others aspects are limited by few factors: (1) technical abilities of obtaining full sequences of lake sediments, (2) indicating the age of analyzed sediments, (3) the maintenance state of a plant and animal parts what influence the precision of identification and (4) lack of sufficient knowledge within ecology what limits the bioindicative meaning of the identified fossiled parts.. ECO-EVO ARE LIMNOLOGISTS INTERESTED IN? JOANNA PIJANOWSKA Department of Hydrobiology, University of Warsaw Banacha 2, 02-097 Warszawa email: jopi@hydro.biol.uw.edu.pl The research programs of American and European scientists are aimed to integrate ecology and evolutionary biology (eco-evo). Nowadays also with 9
developmental biology, to produce an integrative approach, so called eco-evodevo. Such an integration gives a chance to both: ecologists to find answers to questions, concerning the functioning of an organism in its environment and to physiologists, molecular biologists or biochemists to discover the mechanisms governing the adaptations to life in a variable and adverse environment. It also increases probability to publish in top journals. The sole description of an ecological phenomenon, even spectacular, is not satisfactory enough. Further questions have to be answered, concerning its evolutionary sense and, also, mechanism governing its expression. Limnology does not follow these postulates. Is then there any future ahead traditional limnologists? HAZARDOUS WATER BLOOMS NOT ONLY THE HYDROBIOLOGICAL PROBLEM MARCIN PLIŃSKI Institute of Oceanography, Gdańsk University, al. Marszałka Piłsudskiego 46, 81-378 Gdynia e-mail: ocemp@univ.gda.pl Water blooms as a natural phenomenon are known for many years. It is joint with the mass growth of algae occurring in the water bodies. The toxic phytoplankton blooms observed in the last few years are caused by the eutrophication. Dinoflagellates and golden-brown flagellates are the main producers of toxins in the marine environment, but the cyanobacteria (bluegreen algae) in the inland waters. Cyanobacterial blooms present hazards to animal and human health because all of the species which characteristically form the blooms are capable of producing potent toxins. Animal fatalities, birdand fish-kills associated with cyanobacterial blooms, or attributed to cyanobacterial toxins, have been reported from around the world for more than a century. Common potentially toxic cyanobacteria in the freshwater include the unicellular Microcystis genus and the filamentous genera Anabaena, Planktothrix, Aphanizomenon and Nodularia. The alkaloid neurotoxins anatoxin-a and homoanatoxin-a are postsynaptic neuromuscular blocking agents, resulting in death by respiratory arrest. The alkaloid toxins saxitoxin and neosaxitoxin are sodium channel-blocking agents causing paralysis. Signs associated with cyanobacterial neurotoxicoses include muscule fasciculations, lethargy, collapse, cyanosis, opisthotonos in birds and convulsions. The hepatotoxins include a cyclic heptapeptide group microcystin and cyclic pentapeptides (nodularins); they are slower acting than neurotoxins. Microcytins and nodularins are accumulated in the liver where they bind irreversibly and inhibit key regulatory enzymes (protein phosphates). Sings of poisoning include weakness, lethargy, pallor, cold extremities, bloody diarrhoea, respiratory 10
distress and coma, with death occurring due to cardiovascular collapse within a few hours to several days. There have been no noticed the immediate human mortal intoxication caused by hepatotoxins. Till now we have no effective technical methods preventing cyanobacterial blooms. Widely education in the field of potentially hazards causing by the contact with water having sings of cayanobacterial blooms is recommended. WATER QUALITY ASSESSMENT IN POLAND IN THE VIEW OF EU REQUIREMENTS HANNA SOSZKA Institute of Environmental Protection, Kolektorska 4, 01-692 Warsaw, e-mail: hasoszka@ios.edu.pl Water Framework Directive accepted in 2000 is considered to be the most important and modern piece of legislation establishing a framework for the Community action in the field of water policy. Implementing WFD requirements concerning water assessment and classification constitutes a big challenge for all EU countries. The directive promotes quite new approach to the issue, introducing the assessment of the ecological and chemical status, which together create a general view of surface water conditions. Ecological status of the water body represents structure and functioning of aquatic ecosystem, and is assessed as the deviation from reference conditions. The basis of ecological status assessment are so-called biological elements, in other words assemblages of aquatic organisms inhabiting waters (phytoplankton, macrophytes and phytobenthos, benthic macroinvertebrates and fish). When introducing WFD requirements Member States faced the necessity to elaborate (by 2006) biological assessment methods related to the reference conditions. Countries which had a long tradition in biological monitoring (i.e. Germany, Austria and Great Britain), owned a large database and practised traditional biological assessment methods, didn t find the task so problematic. These countries can also benefited from a number of projects launched since late 90 s aimed at establishing new assessment methods compliant with WFD or adaptation of traditionally used methods to new requirements. Countries which ran the biological monitoring in a limited range (as the case was in Poland) elaborate new biological assessment methods and implement them to monitoring practice with a significant delay. The reason for this situation is the lack of uniform biological databases (on the whole country scale) and insufficient scientific basis for designing classification systems. These should be a result of profound knowledge about reaction of aquatic assemblages to different types of pressure in quantitative terms. Extended 11
involvement of scientific society in these works could significantly speed up implementation of assessment methods compliant with WFD in Poland. 12
Darvinian thinking in limnology DARWIN AND LIMNOLOGY IN A DOMESTICATED WORLD STANLEY I. DODSON Zoology Department, 444 Birge Hall University of Wisconsin 430 Lincoln Drive Madison, WI 53706-1381, USA e-mail: sidodson@wisc.edu The world landscape has become domesticated since Darwin s time, but limnologists use adaptation, a pre-domestication concept, to explain workings of aquatic communities, even though adaptations are contextdependent. A characteristic of postdomesticated Earth is the rapidly-changing ecological context, in which our challenge as limnologists is to discover how to apply adaptation theory. Limnologists use evolutionary theory as a basic tool for explaining how aquatic systems are structured and how they work. For example, the mechanisms of the PEG model are based on the assumption that aquatic organisms are adapted to their environment and to each other. However, domestication has changed Darwin s world, through species invasions, extinctions, replacement of natural with artificial habitats, and new kinds of water chemistry. Thus, domestication of the Earth changes aquatic environments and communities and favors weedy ubiquitous species, and probably changes the ways in which limnological information can be applied to management of aquatic resources. Nevertheless, the next generation of limnologists will make the transition to using evolution from the domesticated-earth perspective. DARWINIAN NATURAL SELECTION: WHY ITS WAY TO ECOLOGY HAS BEEN SO LONG? ALEXEI GHILAROV Department of General Ecology, Biological Faculty of M.V. Lomonosov University, Moscow 119991, Russia e-mail: ghilarov@rambler.ru Although Ernst Haeckel, who coined in 1866 the term ecology, was the ardent supporter of Darwinism, ecology for a long time developed without any influence of evolutionary views. Even in 1920 30s the time when the foundations of contemporary ecology were laid, evolutionary approach was 13
rather declared than practically used. To understand the reason of such situation we should address the roots of ecology and changing demands of this science for theoretical background. The first, perhaps principal, root of ecology is natural history, an ancient form of inquiry originally oriented at the description and classification of organisms. The second one is general systems theory, the belief that there are some basic laws or rules that govern the functioning of any dynamic system. If we radically simplify the whole content of ecology we see that the main stuff of this science till recent time was typical for natural history. However the methods of organizing and arrangement of raw material were different. If for classical natural history it was nomination of the visible, for ecology it was the revealing of some general principles, that underlie population dynamics, community organization, or ecosystem functioning. In such structure of ecology there was no place for Darwinism simply because ecology didn t need it. However every science has some inner logic of development, a succession of tasks that arises one after another. What we see now is the movement from statement of general principles to more deep understanding of nature in the details. New tasks demand new organizing principles. Darwinism is the name of one of such principles. Recently Oleg Kosterin, entomologist from Novosibirsk, has aptly noted that the main sense and greatness of Darwinism is the statement about absence of special evolutionary mechanism that imply some aim (in any sense) as the cause of evolutionary changes. This simple idea for a long time was not appreciated by scientific community. Ecologists were no exception. CAN DAPHNIA REDUCE THE COSTS OF ANTIPREDATION DEFENSES WHEN GROWN AT LOW POPULATION DENSITY LEVEL? MACIEJ GLIWICZ, WOJCIECH USZKO, PIOTR MASZCZYK Department of Hydrobiology, Faculty of Biology, University of Warsaw Banacha 2, 02-097 Warszawa, e-mail: gliwicz@hydro.biol.uw.edu.pl Daphnia (D. hyalina galeata) were grown in batch culture or flow-through plankton organ chambers in medium containing high levels of Scenedesmus food (1 mg organic carbon L-1) at either low or high population density levels (1 and 60 Daphnia L-1, respectively), in the presence or absence of fish (roach Rutilus rutilus) kairomones. In the presence (but not in the absence) of kairomones, antipredation defenses were weaker in Daphnia grown at low population density: they remained closer to the surface in daylight, their guts were fuller, their body growth faster, the number of eggs per clutch at first reproduction greater and their daily investment in reproduction higher. These observations suggest that Daphnia is able to use low population density as an antipredation refuge and maximizes its fitness in this situation by giving up costly 14
antipredation defenses. This ability may allow Daphnia to quickly restore high density levels after a population collapse. Experiments with live fish (roach) demonstrated that giving up antipredation defenses at low population density levels makes Daphnia more vulnerable to fish predation when the population density becomes high enough to make Daphnia prey attractive to fish again, showing that increased fitness is readily lost when population density increases rapidly. HOW HAVE THE STRATEGIES FOR RESTORING LAKES USING LAKE BIOMANIPULATION BENEFITED FROM THE LIFE-TIME RESEARCHES OF MACIEJ GLIWICZ? RAMESH D. GULATI NIOO/Centre for Limnology, 3631 AC Nieuwersluis, The Netherlands e-mail: r.gulati@nioo.knaw.nl The literature search on Lake Biomanipulation indicates a rather limited, active involvement of Maciej Gliwicz with lake restoration studies. Moreover, as many other eminent freshwater ecologists, Maciej seems to have his reservations: he is, apparently, even pessimistic about lake biomanipulation as a sustainable food-web measure for restoring or rehabilitating lakes. And he is probably right! Many of Maciej s studies concern the cascading top-down effects of piscivorous fish on planktivorous fish and, in return, of the planktivorous fish on large-bodied herbivorous zooplankton. A perusal of Maciej s field studies leads to several interesting revelations. He provides us with an excellent insight into the organisms and their populations and the factors that determine their fitness in the food-web, i.e. the factors that should be in place and operating, if the biomanipulation measures were to succeed in producing the desired results. In this lecture, I attempt to provide a brief expose of Gliwicz s s life-time works, both in the field and laboratory, generally obtained from his published papers in the ISI Journals. Most of this information is also nicely collated and condensed in his book Between Hazards of Starvation and Risks of predation: The Ecology of Offshore Animals. I will attempt to show how some of Gliwicz s findings are at the base of strategies employed to biomanipulate lakes, especially in the north-west Europe and the US, and comment upon why there are far more cases of failure than success of biomanipulation. 15