2.7.–7.7. 2017 / Olomouc, CZ ABSTRACT BOOK 2 ABSTRACT BOOK Keynote – Presentation IMPLICATIONS OF GLOBAL CHANGE FOR AQUATIC COMMUNITIES: DO MICRO-EVOLUTIONARY SHIFTS IN POPULATION FUNCTIONAL TRAITS MAKE A DIFFERENCE? Steven Declerk ([email protected])1 1 Netherlands Institute of Ecology, Wageningen, NL By most ecologists, species are considered as entities with fixed traits because rates of evo- lutionary adaptations are believed to be much slower than the rate of ecological dynamics. However, it is only in the latest years that an increasing number of ecologists come to re- alize that microevolutionary adaptation can take place at ecological time scales. Although microevolutionary trait shifts may seem small and insignificant in magnitude compared to the large trait changes that are documented for macro-evolutionary time scales, they may still be of considerable importance from an ecological perspective, as they may strongly determine the performance of contemporary populations and their interactions with the biotic and abiotic environment. This is especially relevant in the context of current glob- al change, with anthropogenic impacts that cause the biotic and abiotic environment of organisms to change at unprecedented rates. In this talk, I will introduce the concept of eco-evolutionary dynamics, illustrate its relevance for aquatic systems with a variety of examples and try to address the question whether such dynamics may effectively contrib- ute to a better understanding of the response of aquatic biota to anthropogenic pressures. / 2.7.–7.7. 2017 / OLOMOUC, CZ 3 Keynote – Presentation SERENDIPITY IN SCIENCE – 35 YEARS STUDYING A TROPICAL LAKE David Harper ([email protected])1 Nic Pacini2 1 University of Leicester, UK 2 University of Calabria Lake Naivasha, Kenya, was once a rather unusual lake, but is becoming ordinary as it fills with alien species that are now commonplace and it becomes surrounded by developments and settlements. This presentation looks at 50 years of change in the lake through the 35 years we have been studying it and whether the knowledge of its limnology acquired, is any use in its management. A small (100-140km2) freshwater lake in a chain of mostly saline-al- kaline lakes running along the predominantly arid Eastern Rift Valley floor between Ethio- pia and Tanzania, Naivasha has always been essential to human existence and, since colo- nization in the lake 19th Century, drawn settlement. People had little impact on its ecology before the middle of the 20th Century, but an increasing list of deliberate introductions and accidental arrivals of alien species, that is still continuing, mean that the lake ecosystem is wholly novel beneath the water, yet can appear little changed above. In parallel to the alien invasion, agricultural and horticultural developments, bringing several hundred thousand people in new settlements, have markedly changed the lake hinterland and threatened its water quality. Intense subsistence cultivation throughout the catchment with increasing population reduce the quality and quantity of incoming river waters. Against these threats to its ecology, the lake responds with the most fickle hydrology imaginable, as a conse- quence of the Inter Tropical Convergence Zone. Seemingly about to become a dustbowl in 2009 through over-abstraction on top of a natural drought, that brought international experts to help write yet more management plans, the lake responded in heavy rains by rising by 2012 to a level last seen in 1969, with native species and high water quality re- turning. With such un-predictability and a near-impossibility of modeling, how useful is its science? Naivasha has been a great training ground for students and foreign scientists as a first ‘taste’ of Africa, but none of the science has generated any effective monitoring at all to guide sustainable management. Will this change? I shall give you a mentally easy pres- entation, to help you wake up, on the morning after the conference dinner. 4 ABSTRACT BOOK Keynote – Presentation MICROBIAL NITRIFICATION IN URBAN STREAMS: FROM SINGLE CELL ACTIVITY TO ECOSYSTEM PROCESSES Stephanie N. Merbt ([email protected])1 1 EAWAG, Switzerland Ammonia oxidization is the first and rate-limiting step of nitrification, which connects eco- systems’ nitrogen (N) inputs (fixation, mineralization) with losses (denitrification, anamox). Ammonia oxidization is carried out by both ammonia oxidizing archaea (AOA) and bac- teria (AOB). Although sharing a common function, AOA and AOB are phylogenetically dis- tinct, suggesting different ecological adaptations and phenotypic characteristics. In high N loaded ecosystems, such as urban streams receiving effluents from wastewater treatment plants (WWTP), ammonia oxidization is highly relevant, and microbial biofilms growing on submerged substrata carry out a fundamental role. Despite the pivotal effect of high N concentrations in triggering eutrophication of downstream waters, there are only few mechanistic insights on how ammonia oxidation is controlled in human altered streams. In my PhD thesis, I aimed to unveil regulating factors and driving mechanisms of ammonia oxidation from single cell to community and ecosystem scales through the combination of a large variety of molecular and biogeochemical tools in both field and laboratory experi- ments. In my presentation, I will show how the effluent of WWTPs shapes the distribution, community composition and activity of AOA and AOB and how this shift is reflected in dif- ferential nitrification rates at ecosystem scale. Moreover, I will unveil differential photo- sensitivity of ammonia oxidizing organisms as an important driver for niche separation; and how habitat heterogeneity within stream reaches influences the spatial distribution of ammonia oxidizers at whole-reach scale. Finally, I will evaluate the relative contribution of different microbial communities (epilithic and epipsammic biofilms) to whole-reach nitri- fication. / 2.7.–7.7. 2017 / OLOMOUC, CZ 5 Keynote – Presentation NEW PERSPECTIVES IN THE STUDY OF LAKE FOOD WEBS Jake Vander Zanden ([email protected])1 1 Center for Limnology, Madison, WI, United States of America In this current era of unprecedented global environmental change, studying lakes from a system-wide perspective provides a holistic basis for understanding and conserving lake ecosystems. In this talk, I’ll highlight several insights into our understanding of lakes that derive from adopting a food web perspective. First, benthic primary production can be an important contributor to whole-lake primary production, and seems to make a dispropor- tionately large contribution to higher trophic levels. Second, lakes are linked to the sur- rounding landscape through aquatic insect emergence events. Studies from Lake Myvatn, Iceland have provided a basis for better understanding the role of lake-to-land food web linkages. Finally, compound-specific stable isotope studies are providing new insights into long term food web change and historical niche partitioning in fish communities. Food web studies as discussed here are part of a larger movement to apply more holistic and system-wide approaches to the study of lakes. 6 ABSTRACT BOOK RS02 – Presentation A STUDY OF THE POTENTIAL IMPACTS OF CLIMATE CHANGE ON OYSTER PRODUCTION IN WHIN ESTUARY IN GHANA Sandra Akugpoka Atindana ([email protected])1 Sandra Brucet2 1 University for Development Studies, Ghana 2 Olajire, Fagbola Ghana depends heavily on her coastal resources for food, income and employment with the Whin Estuary being no exception. It is feared that this ecosystem could be lost in the event of Climate Change (CC) because of its close tie to the sea. This could be magnified by land use activities due to potential impact on food security, livelihood and water. Using case scenarios, historic mollusc catch and current catch data of West African Oyster (Cras- sostrea tulipa) and environmental factors were used as surrogates of the ecological sta- tus and sustainability of oyster fishery. Triangulation approach involving the use of focus group discussions, key informant interview, field measurements and observations were employed to solicit data on catch, land use activities and perception of oyster harvesters on the fishery. A general linear model was performed to determine the influence of envi- ronmental variables on oyster abundance and spatial distribution. Ranking of identified land use stressors were done using the ( Battisti et al., 2009) Salafsky et al. (2003) ranking method. The results of the study showed that mollusc catch decline with increase temper- atures and increase in volume of rainfall. Among the non climatic stressors in the area, the presence of sewage outlets were the major threat (8), followed by uncontrolled mangrove cutting (7), sand winning (6) and the least of the threats were refuse damps(4) and farm- ing activities (3). There was no significant differences in the magnitude of threats of refuse dumps and farming activities. Keywords: Abundance, Catch, Ecological, Oyster, Threats / 2.7.–7.7. 2017 / OLOMOUC, CZ 7 RS02 – Presentation IMPACTS OF CLIMATE CHANGE ON FOOD WEBS: ROLE OF INDIVIDUAL PHENOTYPIC PLASTICITY AND NON-TROPHIC INTERACTIONS David Boukal ([email protected])1 Arnaud Sentis, Charlène Gémard, Baptiste Jaugeon 1 University of South Bohemia, Czech Republic Understanding the dependence of species interaction strengths on environmental factors, species traits and species diversity is crucial to predict