Die Gattung Daphnia nimmt eine zentrale Position im pelagischen Nahrungsnetz vieler Standgewässern (Seen, Talsperren) ein. Aufgrund hoher Filtrierleistungen sind Daphnien für das integrierte Gewässermanagement, z.B. im Rahmen einer Nahrungskettenmanipulation (Biomanipulation), von großem Interesse. Ihre relativ einfache Kultivierbarkeit machte sie außerdem zu einen weit verbreiteten Modellorganismus limnologischer Grundlagenforschung. Das Ziel dieser Arbeit besteht darin, ein umfassendes Modellsystem für die Gattung Daphnia zu entwickeln, das wesentliche Kenntnisse der Ökologie von Daphnia miteinander verknüpft, um eine Vernetzung des Wissens zu realisieren. Bestehende Modellansätze konnten diese Aufgabe nur unzureichend erfüllen, weil sie in der Regel einem "Problem-orientierten Ansatz" folgen und somit sehr unterschiedliche inhaltliche Ausrichtungen und verschiedene Modellstrukturen aufweisen. Eine Kopplung bzw. ein direkter Vergleich dieser Modelle ist deshalb in der Regel schwierig. Dieses Modellsystem wurde entwickelt, um ein Instrument zur Synthese des vorhandenen Prozesswissens bereitzustellen, und nicht, um ein spezifisches, abgegrenztes Problem zu bearbeiten; es steht somit diametral zu existierenden Ansätzen. Aus diesem Grunde wird der gewählte Ansatz als ein "Spezies-orientierter Ansatz" bezeichnet. Drei Eigenschaften charakterisieren diesen Ansatz. (i) Das Modellsystem umfasst mehrere hierarchische Ebenen biologischer Organisation, wobei der Schwerpunkt auf den Ebenen des Individuums und der Population liegt. Interaktionen zwischen diesen Organisationsebenen sind ausgeprägt und in Feld- und Laborstudien gut belegt, in existierenden Modellen aber noch unzureichend miteinander verknüpft. (ii) Da eine quantitative Interpretation der Ergebnisse beabsichtigt ist, wurden die Modellausgaben einer umfangreichen Validation an unabhängigen und bereits publizierten Daten unterzogen. (iii) Das Modellsystem zeichnet sich durch einen geschachtelten Aufbau aus (nested design), wodurch eine einfache Erweiterbarkeit des Modells oder auch die separate Anwendung bestimmter Modellkomponenten gewährleistet ist. / The scope of this thesis was to develop a comprehensive model system of the genus Daphnia, a key organism in the pelagic food web of lakes and reservoirs and a widely used model organism in experimental and theoretical ecology. Although its central role in applied and basic research in aquatic ecology is obvious, there are still fundamental problems in modelling the observed dynamics of Daphnia (for details see chapter 2). Therefore, a basic motivation of this work was to use scientific results obtained in independently conducted research for developing a model that brings these results into context. Instead of following a "problem-oriented" paradigm applicable to a single, well defined problem or scientific hypothesis, the underlying concept of the emerging model system was considered to be "species-oriented". Thus, various relevant processes are included into the framework in order to simulate the dynamics of daphnids displayed on different levels of biological organization. To facilitate its application to various problems in ecological research on the genus Daphnia, the model system fulfills the following three important properties: (1) model outputs are thoroughly validated on experimental data in order to guarantee sound quantitative outputs of the model system (2) the system spans over different levels of biological organization with special emphasis laid upon the individual level and the population level (3) the model´s architecture follows a nested design with a defined individual level model that is integrated into a population level model The whole model system is able to describe an individual´s development over time on basis of physiological properties of the organism and, furthermore, how these individual level processes interact with the dynamics on the population level. Due to its nested design, applications of separate submodels (e.g. the individual-level model) are possible.

In estuaries, like the Indian River Lagoon, mesozooplankton have a vital role in the food web by connecting trophic levels. In this study, mesozooplankton abundance and species composition were monitored weekly on the incoming and outgoing tides from September 2006 to May 2009. For the incoming tide, the mean abundance was 2298.2 mesozooplankton/m3 (+/-325.2), and for the outgoing tide the mean abundance was 1180.0 mesozooplankton/m3 (+/-153.1). The mesozooplankton abundance on the incoming tide was significantly greater than on the outgoing tide. The most abundant type of mesozooplankton was the copepod Acartia tonsa, representing 35.0% and 52.1% of the individuals on the incoming and outgoing tides respectively. Mesozooplankton abundance values were compared with environmental data obtained from the South Florida Water Management District. The strongest positive correlation was found between chlorophyll a concentrations and A. tonsa abundance, likely due to phytoplankton being the primary food source for A. tonsa. / by Miranda Hoover Kerr. / Thesis (M.S.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.

Limnologische Charakterisierung ausgewählter Ackerhohlformen (Sölle) des nordostdeutschen Jungmoränengebietes als Grundlage von Schutzmaßnahmen* *) gefördert durch die Deutsche Bundesstiftung Umwelt und die FAZIT-Stiftung, Frankfurt a.M. 160 S.: 64 Abbn., 24 Tab., 3 gezeichnete Tafeln, 4 mikroskopische Tafeln Humboldt-Universität zu Berlin Institut für Biologie AG Ökologie Die Untersuchungen konzentrierten sich auf das Plankton von Söllen der Jungmorä nenlandschaft Nordostdeutschlands. Ziel war es, die qualitative und quantitative Phyto- und Zooplanktonstruktur verschiedener Sölle unter dem Gesichtspunkt der nterschiedlichen Landnutzung, des Wasserhaushaltes und des Stoffeintrages in zwei Untersuchungsgebieten zu erfassen, mit einem weitgehend ursprünglichen Forstsoll zu vergleichen und daraus Schlußfolgerungen für den Erhalt und den Schutz dieser Kleingewässer abzuleiten. Es wurden sieben repräsentative Sölle monatlich über drei Vegetationsperioden (1994-1997) untersucht. Neben dem Artenspektrum und dem Abun danzwechsel des Phyto- und Zooplanktons erfolgte eine Erfassung des Chlorophyll a -Gehaltes der Mikroalgenzellen, der hydrochemischen und physikalischen Grundparameter und der Pegelstände des Sollwassers. Trotz der großen Individualität der Untersuchungsgewässer konnten aus den Erg ebnissen die Sölle in drei Gruppen statistisch signifikant zusammengefaßt werden. Für deren Abgrenzung sind die Nährstoffverhältnisse (N oder P-Überschüsse, Nitrifikationsgrad), die Sauerstoffsättigungswerte und das Artenspektrum des Phyto- und Zooplanktons bedeutsam. Hohe Leitfähigkeit des Wassers besonders in den Söllen des Gebietes um Lietzen-Döbberin wird durch hohe Sulfat- und Chloridgehalte bedingt. Im Vergleich zu den Seen sind die Chlorophyll a -Konzentrationen als Biomasseäquivalent für die Mikroalgen in Relation zu den Phosphatgehalten auffallend gering. Aus den Ergebnissen lassen sich Maßnahmen zur Erhaltung und dem Schutz der Sölle ableiten. Es wird die konsequente Verminderung der externen Nährstoffeinträge durch die Schaffung und/ oder Pflege von Pufferzonen sowie gegebenenfalls die Umwidmung des Einzugsgebietes in Dauergrünland empfohlen. Weitere Maßnahmen, die auf die Reduzierung der internen Nährstoffreserven zielen, sind erst nach zusätzlichen Untersuchungen insbesondere zum Phosphorbindungsvermögen der Sedimente für die Sölle ableitbar. / Limnological characterization of selected ponded depressions of the north German young moraine site as a basis for conservation* *) sponsored by the Deutsche Bundesstiftung Umwelt and the FAZIT-Stiftung, Frankfurt a.M. 160 S.: 64 Abbn., 24 Tab., 3 graphic Tables, 4 microscope tables Humboldt-Universität zu Berlin Institut für Biologie AG Ökologie The main geographical feature of the ground and terminal moraines of northern Germany are the numerous small depressions, many of which are water-filled. They represent a typical geographical element of this region and in the German language are usually referred to as "Sölle" (Singular = "Soll"). These small bodies of water were created either glacially through the melting of dead-ice pieces (natural depressions or dead-ice depressions) or later (circa 12th or 13th century) in the course of the clearing of large tracts of forested land through the partial and permanent damming of depressions (pseudo depressions). The study concentrated on the plankton levels of ponded depressions in the recent moraines of northern Germany. The goal of the study was to record the qualitative and quantitative phytoplankton and zooplankton make-up of several different ponded depressions with consideration of the various land uses, management of water, and introduction of nutrients in two research areas and to compare these findings with a mostly unaltered forested ponded depression (ponded depression in a forested area) for the purpose of deriving conclusions about the preservation and protection of these small water ways. Seven representative ponded depressions were examined monthly over the span of three vegetation periods (1994-1997). In addition to the variety of vegetational species and the variation in amounts of phytoplankton and zooplankton, data about the amount of chlorophyll a in the micro algae cells, the hydro-chemical and physical ground parameters, and the water level of the ponds was recorded. In spite of the considerable uniqueness of each of the ponds under examination, the results of the study allowed for the classification of the ponded depressions into three statistically significant groupings.The proportions of nutrients (a surplus of N or P or the level of nitrification), the oxygen saturation values, and the vegetational spectrum of phytoplankton and zooplankton proved meaningful for the differentiation of the groupings. High conductivity of the water, especially in the ponds in the area around Lietzen-Döbberin, is caused by high levels of sulfate and chloride. In comparison to lakes, the concen trations of Chlorophyll a as a biomass equivalent for the micro algae are noticeably smaller in relation to the phosphate levels. The results of the research suggest measures for the preservation and protection of the ponded depressions. The intentional reduction of external nutrients through the creation of and/or care for buffer zones and, if necessary, the redesignation of areas zoned for development into permanent nature conservation zones is recommended. Further preservation measures, aimed at reducing the reserves of internal nutrients, will only be deduced after further study of the ponded depressions, especially in relation to the ability of the sediment to absorb phosphors.

Ng, Ka Yan. / "November 2009." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 329-399). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstract (English) --- p.iv / Abstract (Chinese) --- p.ix / Contents --- p.xii / List of Tables --- p.xix / List of Figures --- p.xxi / Chapter Chapter 1 --- General Introduction / Chapter 1.1 --- Seaweeds as Beneficial Resources to Humans --- p.1 / Chapter 1.2 --- Seaweed Communities as a Habitat --- p.5 / Chapter 1.2.1 --- Reasons for being a Favourable Habitat in the Ocean ´Ø and the Coastal Region --- p.5 / Chapter 1.2.2 --- Characteristics of Seagrass Habitat and its Associated Faunal Communities --- p.8 / Chapter 1.2.3 --- Characteristics of Seaweed Habitat and its Associated Faunal Communities --- p.9 / Chapter 1.2.3.1 --- Seasonality --- p.9 / Chapter 1.2.3.2 --- Structural Complexity --- p.10 / Chapter 1.2.3.3 --- Canopy Effect on Biota --- p.10 / Chapter 1.3 --- Marine Environment and Sargassum Communities in Hong Kong --- p.11 / Chapter 1.4 --- Study Organism: the Sargassum siliquastrum --- p.14 / Chapter 1.5 --- Study Significance and Objectives --- p.16 / Chapter 1.6 --- Study Sites --- p.18 / Chapter 1.7 --- Thesis Organization --- p.21 / Chapter Chapter 2 --- Zooplankton Assemblage in Seaweed Bed of Sargassum siliquastrum and Its Temporal Variation / Chapter 2.1 --- Introduction --- p.27 / Chapter 2.2 --- Materials and Methods --- p.34 / Chapter 2.2.1 --- Sample collection --- p.34 / Chapter 2.2.2 --- Data acquisition --- p.36 / Chapter 2.2.3 --- Data analysis --- p.37 / Chapter 2.3 --- Results --- p.39 / Chapter 2.3.1 --- Temporal Change in Zooplankton Assemblage Composition --- p.39 / Chapter 2.3.1.1 --- Change in Zooplankton Abundance with Time --- p.43 / Chapter 2.3.1.2 --- Temporal Change in Zooplankton Species Composition --- p.44 / Chapter 2.3.2 --- Effects of Vegetation on Zooplankton Assemblage Structure --- p.47 / Chapter 2.3.2.1 --- Comparison between Vegetated and Unvegetated Habitats in terms of Zooplankton Community Structure --- p.47 / Chapter 2.3.2.2 --- Comparison between Vegetated and Unvegetated Habitats in terms of Zooplankton Abundance --- p.50 / Chapter 2.3.2.3 --- Comparison between Vegetated and Unvegetated Habitats in terms of Zooplankton Species Composition --- p.51 / Chapter 2.3.3 --- Temporal Trends of Environmental Factors and their Relationship with Zooplankton Assemblage --- p.58 / Chapter 2.3.4 --- Relationship between Zooplankton Assemblage and Seaweed Phenology --- p.59 / Chapter 2.4 --- Discussion --- p.61 / Chapter 2.4.1 --- Macro-distribution Pattern and Temporal Change in Zooplankton Assemblage Structure in Sargassum siliquastrum Bed --- p.61 / Chapter 2.4.2 --- Effects of Vegetation on the Micro-distribution of Zooplankton within and between Habitats ´ؤ Relationship between Sargassum Phenology and the associated Zooplankton Assemblage Structure --- p.66 / Chapter 2.4.3 --- Species Composition of Zooplankton Assemblage in Seaweed Bed of Sargassum siliquastrum and its Potential Role as Nursery Ground for Fishery Resources --- p.70 / Chapter 2.5 --- Summary and Conclusion --- p.74 / Chapter Chapter 3 --- Effects of Seaweed Canopy on the Structure of Zooplankton Assemblage in the Sargassum siliquastrum Bed / Chapter 3.1 --- Introduction --- p.118 / Chapter 3.2 --- Materials and Methods --- p.121 / Chapter 3.2.1 --- Sample collection --- p.121 / Chapter 3.2.2 --- Data acquisition --- p.122 / Chapter 3.2.3 --- Data analysis --- p.123 / Chapter 3.3 --- Results --- p.125 / Chapter 3.3.1 --- Effects of Canopy on Zooplankton Community Structure --- p.125 / Chapter 3.3.2 --- "Comparison between Control, Treatment and Unvegetated Habitats in terms of Zooplankton Abundance and Its Temporal Variation" --- p.127 / Chapter 3.3.3 --- "Comparison between Control, Treatment and Unvegetated Habitats in terms of Zooplankton Species Composition and Its Temporal Variation" --- p.128 / Chapter 3.4 --- Discussion --- p.134 / Chapter 3.4.1 --- Effects of Canopy Removal on the Zooplankton Assemblage Structure --- p.134 / Chapter 3.4.2 --- Role of Seaweed Canopy in Zooplankton Community and the Potential Impacts of Canopy Removal on the Coastal Ecosystem --- p.137 / Chapter 3.5 --- Summary and Conclusion --- p.141 / Chapter Chapter 4 --- Epiphytic Faunal Assemblages in Seaweed Bed of Sargassum siliquastrum and its Temporal Variation / Chapter 4.1 --- Introduction --- p.153 / Chapter 4.2 --- Materials and Methods --- p.161 / Chapter 4.2.1 --- Sample collection --- p.161 / Chapter 4.2.2 --- Data acquisition --- p.162 / Chapter 4.2.3 --- Data analysis --- p.163 / Chapter 4.3 --- Results --- p.165 / Chapter 4.3.1 --- Temporal Change in Epiphytic Faunal Assemblage Composition and Comparison among Sites --- p.165 / Chapter 4.3.1.1 --- Temporal Change in Epiphytic Faunal Density and Comparison among Sites --- p.171 / Chapter 4.3.1.2 --- Temporal Change in Epiphytic Faunal Species Richness and Comparison among Sites --- p.172 / Chapter 4.3.1.3 --- Temporal Change in Epiphytic Faunal Species Composition --- p.175 / Chapter 4.3.1.4 --- Occurrence of Caprellidean and Its Variation with Seaweed Growth Stages --- p.179 / Chapter 4.3.2 --- Temporal Trends of Environmental Factors and their Relationship with Epiphytic Faunal Assemblage --- p.179 / Chapter 4.4 --- Discussion --- p.181 / Chapter 4.4.1 --- Temporal Change in Epiphytic Faunal Assemblage Structure --- p.181 / Chapter 4.4.2 --- Species Composition of Epiphytic Faunal Assemblage in Seaweed Bed of Sargassum siliquastrum and Its Potential Role as Nursery Grounds --- p.191 / Chapter 4.4.3 --- Distribution of Epiphytic Fauna in Seaweed Bed of Sargassum siliquastrum among Different Localities --- p.196 / Chapter 4.4.4 --- Relationship of Epiphytic Faunal Assemblage with Environmental Factors --- p.197 / Chapter 4.5 --- Summary and Conclusion --- p.198 / Chapter Chapter 5 --- Relationship of Epiphytic Faunal Assemblage with the Structural Complexity of Seaweed Sargassum siliquastrum / Chapter 5.1 --- Introduction --- p.234 / Chapter 5.2 --- Materials and Methods --- p.239 / Chapter 5.2.1 --- Sample collection --- p.239 / Chapter 5.2.2 --- Data acquisition --- p.241 / Chapter 5.2.3 --- Data analysis --- p.243 / Chapter 5.3 --- Results --- p.245 / Chapter 5.3.1 --- Effects of Macroalgal Structural Complexity on the Associated Epiphytic Faunal Assemblage Structure --- p.245 / Chapter 5.3.1.1 --- Effects on Epiphytic Faunal Abundance --- p.245 / Chapter 5.3.1.2 --- Effects on Epiphytic Faunal Species Richness --- p.247 / Chapter 5.3.1.3 --- Relationship among Parameters of Sargassum siliquastrum --- p.248 / Chapter 5.3.2 --- Within-plant Zonation of Epiphytic Faunal Assemblage Structure --- p.249 / Chapter 5.3.2.1 --- Within-plant Distribution of Epiphytic Faunal Density --- p.250 / Chapter 5.3.2.2 --- Within-plant Distribution of Epiphytic Species Richness --- p.252 / Chapter 5.3.2.3 --- Within-plant Distribution of Epiphytic Faunal Species Composition --- p.253 / Chapter 5.3.2.4 --- Physical Parameters Associated with Each Zone of Sargassum siliquastrum --- p.257 / Chapter 5.4 --- Discussion --- p.260 / Chapter 5.4.1 --- Effects of Macroalgal Structural Complexity and Biomass on the Associated Epiphytic Faunal Assemblage Structure --- p.260 / Chapter 5.4.2 --- Within-plant Zonation of Epiphytic Faunal Assemblage Structure --- p.264 / Chapter 5.5 --- Summary and Conclusion --- p.273 / Chapter Chapter 6 --- Synthesis and Perspectives --- p.320 / References --- p.329

Phytoplankter sind die bedeutendsten Primärproduzenten in aquatischen Ökosystemen und leisten ca. 45 % der globalen Primärproduktion. Sie weisen eine hohe taxonomische Diversität mit vielfältigen morphologischen und physiologischen Eigenschaften auf. Funktionelle Eigenschaften, die das licht-, temperatur- und nährstoffabhängige Wachstum sowie Verlustgrößen (Fraß, Sedimentation) beschreiben, sind eine Möglichkeit Phytoplankter zu klassifizieren. Diese Einteilung gewinnt für das Verständnis und die Modellierung der Phytoplanktonsukzession (z.B. in Wassergütemodellen) immer mehr an Bedeutung, da nicht taxonomische, sondern funktionelle Eigenschaften das Vorkommen der Phytoplankter im Gewässer bestimmen. Das Wassergütemodell SALMO ist ein mechanistisches, dynamisches, vertikales 1D-Modell, welches Nährstoffe, Sauerstoff, Detritus, 4 funktionelle Phytoplanktontypen und eine Zooplanktonmischgruppe simuliert. Bei der Modellanwendung wurde ersichtlich, dass die vorhandenen funktionellen Typgruppen teilweise nicht ausreichen, um die funktionelle Diversität der realen Phytoplanktongemeinschaften adäquat widerzuspiegeln. Deshalb wird eine Erweiterung der funktionellen Typgruppen in SALMO angestrebt. Eine empirische Freilanddatenanalyse an zwei morphologisch und trophisch verschiedenen Talsperren ergab insgesamt 10 funktionelle Phytoplanktontypen (Typgruppen 1, 2 und 4 bereits in SALMO vorhanden). Die bestehenden funktionellen Eigenschaften wurden erweitert und teilweise verändert (insgesamt 10 funktionelle Eigenschaften). Die neue funktionelle Typgruppe 6 (unbewegliche, koloniale, gelatinöse Chlorophyceen) wurde in lichtabhängigen Wachstumsversuchen und Fraßversuchen mit Daphnia galeata × hyalina genauer untersucht. Als stellvertretende Art für diese Typgruppe wurde Sphaerocystis schroeteri gewählt. Die Wachstumsversuche bei 20 °C kennzeichneten Sphaerocystis als Starklichtart mit einer relativ hohen Wachstumsrate (Iopt = 250 µmol m-2 s-1; µmax = 0.96 d-1; 12:12 h Hell-Dunkelzyklus). Eigene Nährmediumsversuche wiesen auf eine Abhängigkeit von freiem CO2 hin. Dies bietet eine Erklärung für ihr häufiges Auftreten in oligo- bis mesotrophen Gewässern. Bei Anwesenheit von Daphnia konnte nach 96 h Versuchsdauer eine signifikante Erhöhung der Koloniegröße (Anteil nicht fressbarer Kolonien 3-74 %), im Vergleich zur Kontrolle (Anteil nicht fressbarer Kolonien 0-5 %), festgestellt werden. Dies stellt einen effektiven Fraßschutz gegen größenselektiv filtrierendes Zooplankton wie z.B. Daphnia dar und kann bei hohem Fraßdruck zur Dominanz der Typgruppe führen (z.B. Klarwasserphase in eutrophen Gewässern). Der Effekt war nicht durch Infochemikalien induzierbar. Aus Literaturdaten wurde eine relativ hohes Topt von 27 °C, eine nur mäßige Konkurrentstärke um Phosphor (mittlerer KP-Wert) sowie eine Brutto-Sinkgeschwindigkeit von 1.5 m d-1 entnommen werden. / Phytoplankter are the most important primary producer in aquatic ecosystems and contribute about 45 % to global primary production. Phytoplankton communities usually show an enormous taxonomical diversity. However, besides taxonomical diversity, a phytoplankton can also be characterised by its functional diversity by means of functional traits like resource-dependent growth characteristics (e.g. KI-, KP-, KN-values) or sensitivity to zooplankton grazing and sedimentation. Since functional, and not taxonomic, traits drive the phytoplankton succession, a functional classification of phytoplankton is recognised to be increasingly important for the ecological understanding and modelling of plankton succession (e.g. in water quality models). The mechanistic, dynamic, vertical 1D water quality model SALMO simulates the dynamics of nutrient concentrations (P, N), oxygen, detritus, 4 functional phytoplankton types and 1 mixed zooplankton group. Different model applications showed that the number of phytoplankton types in SALMO was sometimes not sufficient for accounting for the observed functional diversity in phytoplankton communities. Therefore, the aim of this thesis is to extend the functional diversity of phytoplankton types in SALMO. After careful evaluation of empirical data from two reservoirs with different morphology and trophic state 10 functional phytoplankton types are proposed (types 1, 2 and 4 remained unchanged). Existing functional traits in SALMO were extended and partly changed (in total 10 functional traits). For the new functional phytoplankton type 6 (non motile, colonial gelatinous green algae) light-dependent growth rates were measured and grazing experiments with Daphnia galeata × hyalina were carried out in the laboratory. For these experiments, Sphaerocystis schroeteri was chosen as representative species for this group. It is characterised by high light demand and relative high growth rates at 20 °C (µmax = 0.96 d-1, Iopt = 250 µmol m-2 s-1, 12:12 h light-dark cycle). Their growth depends on the availability of free CO2. This explains the common occurrence in oligo-mesotrophic water bodies. The range of the colony sizes of Sphaerocystis increased in the presence of Daphnia significantly (portion of inedible colonies 3-74 %) in contrast to the control (portion of inedible colonies 0-5 %). This was induced by direct size-selective grazing and not by infochemicals. Thus, Sphaerocystis has evolved an effective defence mechanism against size-selective filter-feeding zooplankton and is competitive superior at high zooplankton grazing pressure (e.g. clear water stage in eutrophic waters). The lack of experimentally derived parameters for temperature- and phosphorus-depending growth (Tmin, Topt, KP-value) as well as gross sinking velocity was complemented with literature data. The alga is only moderately competitive for phosphorus and exhibits relatively high minimal and optimal growth temperatures (Tmin = 7 °C, Topt = 27 °C). Since type 6 consists of large, non motile species, gross sinking velocity was estimated to be about 1.5 m d-1.

Thesis (Ph. D.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 119-131). Also available on the World Wide Web.

The aims of the thesis were to document the history of the Cladocera (Crustacea) community structure in the Starolesnianske Lake (the High Tatra Mountains, Slovakia) with regards to environmental changes (e. g., Medieval Warm Period, Little Ice Age, anthropogenic acidification, recovery from acidification), and to analyze in detail the development of zooplankton (Cladocera, Copepoda, Rotifera) during the peaking acidification and recovery from acidification (1978 - 2015). Based on results of both the approaches, the appropriateness of using historical data on zooplankton in Tatra lakes between 1909 - 1913 (Minkiewicz, 1914) as a reference condition for the evaluating biological recovery from acidification should have been assessed. The methods used were paleolimnological analyses of lake sediment (namely subfossil Cladocera), analysis of recent zooplankton, and analyses of lake water chemistry. It was found that in the historical record, relative abundances of Cladocera species significantly changed cca 150 years ago (at the end of the Little Ice Age and, in the main, in the period of anthropogenic acidification). The lake, though, has had a very stable species composition of Cladocera during the last cca 2,000 years, represented by four species: Alona quadrangularis, Alonella excisa, Ceriodaphnia...

Phytoplankter sind die bedeutendsten Primärproduzenten in aquatischen Ökosystemen und leisten ca. 45 % der globalen Primärproduktion. Sie weisen eine hohe taxonomische Diversität mit vielfältigen morphologischen und physiologischen Eigenschaften auf. Funktionelle Eigenschaften, die das licht-, temperatur- und nährstoffabhängige Wachstum sowie Verlustgrößen (Fraß, Sedimentation) beschreiben, sind eine Möglichkeit Phytoplankter zu klassifizieren. Diese Einteilung gewinnt für das Verständnis und die Modellierung der Phytoplanktonsukzession (z.B. in Wassergütemodellen) immer mehr an Bedeutung, da nicht taxonomische, sondern funktionelle Eigenschaften das Vorkommen der Phytoplankter im Gewässer bestimmen. Das Wassergütemodell SALMO ist ein mechanistisches, dynamisches, vertikales 1D-Modell, welches Nährstoffe, Sauerstoff, Detritus, 4 funktionelle Phytoplanktontypen und eine Zooplanktonmischgruppe simuliert. Bei der Modellanwendung wurde ersichtlich, dass die vorhandenen funktionellen Typgruppen teilweise nicht ausreichen, um die funktionelle Diversität der realen Phytoplanktongemeinschaften adäquat widerzuspiegeln. Deshalb wird eine Erweiterung der funktionellen Typgruppen in SALMO angestrebt. Eine empirische Freilanddatenanalyse an zwei morphologisch und trophisch verschiedenen Talsperren ergab insgesamt 10 funktionelle Phytoplanktontypen (Typgruppen 1, 2 und 4 bereits in SALMO vorhanden). Die bestehenden funktionellen Eigenschaften wurden erweitert und teilweise verändert (insgesamt 10 funktionelle Eigenschaften). Die neue funktionelle Typgruppe 6 (unbewegliche, koloniale, gelatinöse Chlorophyceen) wurde in lichtabhängigen Wachstumsversuchen und Fraßversuchen mit Daphnia galeata × hyalina genauer untersucht. Als stellvertretende Art für diese Typgruppe wurde Sphaerocystis schroeteri gewählt. Die Wachstumsversuche bei 20 °C kennzeichneten Sphaerocystis als Starklichtart mit einer relativ hohen Wachstumsrate (Iopt = 250 µmol m-2 s-1; µmax = 0.96 d-1; 12:12 h Hell-Dunkelzyklus). Eigene Nährmediumsversuche wiesen auf eine Abhängigkeit von freiem CO2 hin. Dies bietet eine Erklärung für ihr häufiges Auftreten in oligo- bis mesotrophen Gewässern. Bei Anwesenheit von Daphnia konnte nach 96 h Versuchsdauer eine signifikante Erhöhung der Koloniegröße (Anteil nicht fressbarer Kolonien 3-74 %), im Vergleich zur Kontrolle (Anteil nicht fressbarer Kolonien 0-5 %), festgestellt werden. Dies stellt einen effektiven Fraßschutz gegen größenselektiv filtrierendes Zooplankton wie z.B. Daphnia dar und kann bei hohem Fraßdruck zur Dominanz der Typgruppe führen (z.B. Klarwasserphase in eutrophen Gewässern). Der Effekt war nicht durch Infochemikalien induzierbar. Aus Literaturdaten wurde eine relativ hohes Topt von 27 °C, eine nur mäßige Konkurrentstärke um Phosphor (mittlerer KP-Wert) sowie eine Brutto-Sinkgeschwindigkeit von 1.5 m d-1 entnommen werden. / Phytoplankter are the most important primary producer in aquatic ecosystems and contribute about 45 % to global primary production. Phytoplankton communities usually show an enormous taxonomical diversity. However, besides taxonomical diversity, a phytoplankton can also be characterised by its functional diversity by means of functional traits like resource-dependent growth characteristics (e.g. KI-, KP-, KN-values) or sensitivity to zooplankton grazing and sedimentation. Since functional, and not taxonomic, traits drive the phytoplankton succession, a functional classification of phytoplankton is recognised to be increasingly important for the ecological understanding and modelling of plankton succession (e.g. in water quality models). The mechanistic, dynamic, vertical 1D water quality model SALMO simulates the dynamics of nutrient concentrations (P, N), oxygen, detritus, 4 functional phytoplankton types and 1 mixed zooplankton group. Different model applications showed that the number of phytoplankton types in SALMO was sometimes not sufficient for accounting for the observed functional diversity in phytoplankton communities. Therefore, the aim of this thesis is to extend the functional diversity of phytoplankton types in SALMO. After careful evaluation of empirical data from two reservoirs with different morphology and trophic state 10 functional phytoplankton types are proposed (types 1, 2 and 4 remained unchanged). Existing functional traits in SALMO were extended and partly changed (in total 10 functional traits). For the new functional phytoplankton type 6 (non motile, colonial gelatinous green algae) light-dependent growth rates were measured and grazing experiments with Daphnia galeata × hyalina were carried out in the laboratory. For these experiments, Sphaerocystis schroeteri was chosen as representative species for this group. It is characterised by high light demand and relative high growth rates at 20 °C (µmax = 0.96 d-1, Iopt = 250 µmol m-2 s-1, 12:12 h light-dark cycle). Their growth depends on the availability of free CO2. This explains the common occurrence in oligo-mesotrophic water bodies. The range of the colony sizes of Sphaerocystis increased in the presence of Daphnia significantly (portion of inedible colonies 3-74 %) in contrast to the control (portion of inedible colonies 0-5 %). This was induced by direct size-selective grazing and not by infochemicals. Thus, Sphaerocystis has evolved an effective defence mechanism against size-selective filter-feeding zooplankton and is competitive superior at high zooplankton grazing pressure (e.g. clear water stage in eutrophic waters). The lack of experimentally derived parameters for temperature- and phosphorus-depending growth (Tmin, Topt, KP-value) as well as gross sinking velocity was complemented with literature data. The alga is only moderately competitive for phosphorus and exhibits relatively high minimal and optimal growth temperatures (Tmin = 7 °C, Topt = 27 °C). Since type 6 consists of large, non motile species, gross sinking velocity was estimated to be about 1.5 m d-1.

The relative importance of local and regional factors to community build-up is a core issue in contemporary ecology. Studies based on research of newly created aquatic habitats may improve understanding of these processes. We monitored zooplankton colonization rates and community assemblage in 20 newly dug and isolated temporary pools in Kokořínsko Protected Landscape Area. The region is characterised by deep stream valleys, extensive land use, low human influence, low waterfowl migration activity and practically absence of large water bodies. After the first hyproperiod all temporary pools were rebuilt to a permanent form. In contrast to expectations, in both cases we observed immediate colonization of newly created habitats by two main groups of zooplankton (crustaceans and rotifers), but only rotifers (Rotifera) were capable of fast successful establishment of viable populations. Cladocerans (Crustacea: Cladocera) and copepods (Crustacea: Copepoda) were observed rarely and usually in low abundances (< 1 ind-l ). 10 months after the filling of permanent pools one ostracod species (Crustacea: Ostracoda), Notodromas monacha, was recorded as well. During the 8 months of temporary pools existence the presence of 1 cladoceran and 1 cyclopoid copepod species and 12 rotifer taxa was recorded, icluding...

Master of Science / Department of Biology / Craig Paukert / The zebra mussel is an invasive bivalve that was first confirmed in Kansas in 2003, and has decreased zooplankton abundance and altered the aquatic community in other areas where it has invaded. However, little is known about its effects on the aquatic communities of warm-water Great Plains reservoirs. We analyzed zooplankton, benthic macroinvertebrate, and juvenile and small-bodied fish abundance in the littoral zone of an Eastern Kansas reservoir with an established zebra mussel population (El Dorado Reservoir) and a control reservoir without zebra mussels (Melvern Reservoir) for two years pre-zebra mussel invasion (2001-2002) and two years post-invasion (2008-2009). We found no difference in littoral zooplankton abundance between reservoirs across time, but abundance of some macroinvertebrate taxa increased, and abundance of juvenile Lepomis spp. and red shiners decreased in the littoral zone of El Dorado Reservoir in August of the post-zebra mussel invasion period in comparison to the control reservoir. We also analyzed abundance and condition of six adult reservoir fishes in El Dorado Reservoir and three control reservoirs in Eastern Kansas for ten years pre-zebra mussel invasion (1993-2002) and five years post-invasion (2004-2008). Adult white crappie abundance remained constant in El Dorado Reservoir but decreased in the control reservoirs during the post-zebra mussel invasion period, and condition of adult bluegill, white bass, and white crappie decreased in El Dorado Reservoir in the post-zebra mussel invasion period compared to the control reservoirs. Our findings suggest that zebra mussel invasion in El Dorado Reservoir may have affected some benthic macroinvertebrates, juvenile and small-bodied fishes, and adult fishes. We did not find evidence that zebra mussels have had substantial effects on the zooplankton community of El Dorado Reservoir. However, July-August zebra mussel veliger densities in El Dorado Reservoir averaged less than 12 veligers/L in four of the six post-zebra mussel invasion years. Additional research and long-term monitoring of zooplankton, macroinvertebrates, and fishes will be necessary to determine the full effects of zebra mussels on the aquatic communities of warm-water reservoirs throughout North America.