Crustaceans, the most abundant group of organisms that make up zooplankton, form a critical link in the food web between primary-producing phytoplankton and planktivorous fish. Examining this link is essential in order to effectively estimate the amount of energy available to higher trophic levels. The most appropriate currency for tracking energy flow through these food webs is to measure production, or the amount of new biomass generated over a given period of time. Although measurements of primary productivity are routinely made in oceanographic studies, estimates of secondary productivity are rare due to their historical reliance on time-consuming methods. The overall objective of this thesis was to determine the factors influencing temporal variations in community-level crustacean productivity. A simplified lab experiment was used to establish a relationship between diet and chitobiase-based estimates of copepod productivity in response to single versus mixed species phytoplankton diets. In addition, the relationships between primary productivity and chitobiase-based productivity for the entire crustacean zooplankton community were examined over two years in Saanich Inlet, British Columbia, Canada. Lastly, this work determined the abiotic and biotic factors most strongly influencing crustacean productivity in the tropical Guanabara Bay, Rio de Janeiro, Brazil, dominated by the microbial loop. Results from this work show that: (i) copepod populations fed a poor food item take longer to develop through early stages, have lower daily growth rates, and exhibit lower productivity than those fed a good quality food item; (ii) important variations in crustacean productivity are missed when biomass estimates, alone, are used to represent food available to higher trophic levels; (iii) relationships between primary productivity and crustacean productivity can vary interannually and are not necessarily controlled by bottom-up processes; (iv) substantial interannual variations in trophic transfer efficiency (TTE) occur even if average TTE is the same across years; and (v) community-level crustacean productivity in tropical regions dominated by the microbial food loop can be as high as, if not higher than, productivity measured in temperate regions. Ultimately, this work provides insight into how accurate productivity estimates can improve our understanding of zooplankton dynamics in both laboratory and field settings in marine ecosystems worldwide. / Graduate

Since the 1990s water quality monitoring projects using aquatic insects or macroinvertebrates as bioindication in Mongolia has mostly occurred in rivers drainage to the Arctic Ocean. They have been conducted to identify different anthropogentic stressors and impacts upon these running water ecosystems. However, there are still knowledge gaps and uncertainties concerning the research of these macroinvertebrates, in particular, a life cycle study of representative species are one such section of information missing. The specific aim for the study was to determine their life cycles and secondary production of selected species in the Kharaa River Basin, Mongolia, where these animals are exposed to harsh environment conditions. The main challenges for the research project were selecting the most suitable methods for use in the field sampling campaigns as well as establishing biomonitoring criteria for the target species under the extreme harsh climatic conditions. The research also sorts to address the pre-existing taxonomical identification problems. Consequently, a multi-habitat quantitative sampling method, and emergence traps type ‘Model week’ were selected. Five specific traits were chosen as selection criteria from the literature, where the life cycles of numerous species were investigated under comparable conditions to this study. Based on those five distinct criteria, a total of 18 species from EPT group (Ephemeroptera, Plecoptera, and Trichoptera) were selected for deeper analysis. This thesis provided the first quantitative results on the life cycle, production, growth rate and emergence of aquatic insects from Mongolia, to allow comparisons with studies in other regions using the same methods. However, it still needs more quantitative research of population dynamics for a wider range of species including fecundity, accurate development rates, mortality losses (e.g., due to predation), and food availability across environmental gradients of hydraulic conditions and substrate types. In conclusion, last not least it is essential to obtain knowledge especially about life cycle strategies of macroinvertebrates to identify the indicator-properties of single species and to predict re-colonisation potential of disturbed habitats and to evaluate the efficiency of management measures.

Made available in DSpace on 2016-06-02T19:32:09Z (GMT). No. of bitstreams: 1 5730.pdf: 6957633 bytes, checksum: c45a22d4b0d6a4e3858d4318d496940e (MD5) Previous issue date: 2014-02-07 / Financiadora de Estudos e Projetos / In Brazil and other countries the agrochemical carbofurano is largely used, and can reach freshwaters and cause damages to non-target organisms. Rotifera dominates zooplankton communities of most freshwater ecosystems worldwide, both in number of species and density. In the present work biological and ecotoxicological studies in laboratory were carried out with the species Philodina roseola Ehrenberg, 1830 (Rotifera, Bdelloidea) regarding the main aspects of its biology: life cycle, filtration rates, ingestion and secondary production at 25 ± 1.0 °C, besides testing its sensitivity and performance as a test-organism for ecotoxicological studies. Also, a literature review regarding the use of rotifers as testorganisms in the evaluation of pesticides toxicity in freshwaters was carried out for the last three decades. Experiments were performed aiming to assess filtration and ingestion rates of P. roseola feeding on the microalgae Raphidocelis subcapitata at 7 different concentrations. The individual biomass (μg DW ind-1) and secondary production were determined. The main parameters obtained for P. roseola life cycle were: 23.88 ± 3.82 hours duration of embryonic development; 3.5 days generation time; 22.33 ± 2.29 eggs/female total mean fecundity and 23.0 days maximum longevity. Filtration rates varied between 2.715 and 6.615 ml ind-1d-1. Total mean individual secondary production was 0.285692 ± 0.055185 μg ind-1d-1 from which 73.42 ± 5.62 % was allocated into reproduction. P. roseola was an adequate test-organism for ecotoxicological studies considering the life cycle characteristics and response to the pesticide carbofurano with CE50 48-h values of 13.36 ± 2.63 mg L-1 and 89.32 ± 6.52 mg L-1 for the active ingredient and the commercial product, respectively. It was concluded that P. roseola has a fast development time, high metabolism as related to ingestion and filtration rates, high fecundity and moderate sensitivity to the tested pesticide. Studies on its functional response to other factors combinations and sensitivity to other toxicants should be performed. / No Brasil e em outros países o agrotóxico carbofurano é amplamente utilizado, podendo atingir as águas doces e ocasionar danos a organismos não-alvo. Os rotíferos dominam o zooplâncton da maioria dos ambientes aquáticos em todo o mundo, tanto em número de espécies como em densidade. No presente trabalho, estudos biológicos e ecotoxicológicos em laboratório com a espécie Philodina roseola Ehrenberg, 1830 (Rotifera, Bdelloidea) foram realizados, em relação aos principais aspectos de sua biologia: ciclo de vida, taxas de filtração, ingestão e produção secundária a 25 ± 1,0 °C, além de testar sua sensibilidade e desempenho como organismo-teste para estudos ecotoxicológicos. Realizou-se uma revisão de literatura sobre a utilização de rotíferos como organismos-teste na avaliação da toxicidade de pesticidas em águas doces, para as últimas três décadas. Experimentos foram realizados para determinar as taxas de filtração e de ingestão de P roseola, alimentadas com Raphidocelis subcapitata em 7 concentrações diferentes. A biomassa (μg PS. ind-1) e a produção secundária individual foram determinadas. Os principais parâmetros do ciclo de vida de P. roseola foram: desenvolvimento embrionário de 23,88 ± 3,82 horas; idade da primípara de 3,5 dias; fecundidade total média de 22,33 ± 2,29 ovos/fêmea e longevidade máxima de 23 dias. As taxas de filtração variaram entre 2,715 e 6,615 mL ind-1d-1. A produção secundária total foi de 0, 285692 ± 0,055185 μg ind-1d-1 sendo 84,68 ± 3,65 % desta alocada em reprodução. P. roseola é uma espécie adequada como organismo-teste em estudos ecotoxicológicos considerando-se o conjunto de características de seu ciclo de vida e as respostas ao pesticida carbofurano com valores de CE50 48-h de 13,36 ± 2,63 mg L-1 e 89,32 ± 6,52 mg L-1 para o ingrediente ativo e o produto formulado respectivamente. Concluiu-se que P. roseola tem rápido tempo de desenvolvimento, elevado metabolismo em relação às taxas de ingestão e filtração, elevada fecundidade e moderada sensibilidade ao pesticida testado. Estudos sobre suas respostas funcionais a outras combinações de fatores e sua sensibilidade a outros compostos tóxicos deverão ser realizados.

Made available in DSpace on 2016-06-02T19:30:00Z (GMT). No. of bitstreams: 1 5863.pdf: 7083877 bytes, checksum: 4178701e4246ba2359818734ccaf16cf (MD5) Previous issue date: 2014-03-07 / Financiadora de Estudos e Projetos / Reservoirs are ecologically complex and heterogenous environments subject to impacts caused by increased human activities in its hydrographic basin, causing among other disorders, the eutrophication. The phytoplanktonic and zooplanktonic communities can be used as bioindicators for responding quickly to changes that occur in water bodies. The aim this study was to analyze the phytoplanktonic and zooplanktonic communities in Guarapiranga reservoir in relation to different ecological parameters searching to correlate them to hydrodynamic factors and eutrophication. Intensive studies were performed with sampling surveys in both horizontal and vertical axis. Physical and chemical characteristics and also the trophic status of the reservoir were evaluated, and the phytoplanktonic and zooplanktonic communities were studied in relation to species richness, population densities, biomass, secondary production, diversity, uniformity and dominance. The Guarapiranga reservoir is a heterogeneous water body with a small oligotrophic portion, some mesotrophic portions and a larger part eutrophic with high richness of planktonic organisms. The results from two diel cycles characterized the system studied in this period as polymitic, with thermal stratifications interspersed by periods of partial circulation. The air temperature and wind speed were the most important meteorological factors that altered the thermal structure of the reservoir. The phytoplankton was dominated by the cyanobacterium Aphanocapsa delicatissima West and West and the zooplankton by microzooplankton (rotifers and Cyclopoida nauplii). The most eutrophic reservoir compartments were Parelheiros, Embu-Mirim and Guavirutuba. The rotifer Conochlius unicornis Rousselet and the cladoceran Bosminopsis deitersi Richard were indicators of Embu-Guaçu oligo/mesotrophic compartment. The high biomass of Filinia longiseta Ehrenberg in Parelheiros indicated tolerance of this species to extremely eutrophic conditions. The Guarapiranga reservoir is a system with high secondary productivity when compared to other environments of different trophic degree, having as dominant groups the Cyclopoida and rotifers. It was found that Guarapiranga reservoir has high secondary production, but the great load of nutrients needs to be stopped in order to reverse the eutrophication process and to recover the water quality of this important water resource. / Os reservatórios são ambientes ecologicamente complexos e heterogêneos, sujeitos a impactos ocasionados pelo aumento das atividades antrópicas em seu entorno, causando entre outros distúrbios a eutrofização. As comunidades fito e zooplanctônicas podem ser utilizadas como ferramentas de avaliação dos impactos por responderem rapidamente às alterações que ocorrem nos corpos d água. O objetivo deste trabalho foi analisar as comunidades fito e zooplanctônica no reservatório de Guarapiranga em relação a diferentes parâmetros ecológicos buscando correlacioná-las aos fatores hidrodinâmica e eutrofização. Foram feitos estudos intensivos com amostragem em varredura tanto no eixo horizontal como vertical, avaliando as características físicas, químicas e estado trófico do reservatório, bem como as comunidades fito e zooplanctônicas em relação à riqueza de espécies, densidade, biomassa, produção secundária, diversidade, uniformidade e dominância. O reservatório de Guarapiranga é um corpo d água heterogêneo com pequena porção oligotrófica, algumas porções mesotróficas e na maior parte eutrófico, com elevada riqueza de organismos planctônicos. Os resultados da variação nictemeral caracterizaram o sistema neste período estudado como polimítico, com estratificações térmicas intercaladas por períodos de circulação parcial. A temperatura do ar e velocidade do vento foram os fatores meteorológicos mais importantes que alteraram a estrutura térmica do reservatório. O fitoplâncton foi dominado pela cianobactéria Aphanocapsa delicatissima West e West e o zooplâncton pelo microzooplâncton (rotíferos e náuplios de Cyclopoida). As porções mais eutrofizadas foram Parelheiros, Embu-Mirim e Guavirutuba. As espécies Conochlius unicornis Rousselet e Bosminopsis deitersi Richard foram indicadoras do compartimento oligo/mesotrófico Embu-Guaçu. A elevada biomassa de Filinia longiseta Ehrenberg em Parelheiros indicou tolerância da espécie a condições extremamente eutróficas. O reservatório de Guarapiranga é um sistema com elevada produtividade secundária quando comparado a outros ambientes de diferentes graus de trofia, tendo como grupos dominantes Cyclopoida e Rotifera. Concluiu-se que o reservatório de Guarapiranga tem elevada produção secundária, mas o grande aporte de nutrientes precisa ser interrompido para reverter o processo de eutrofização e levar à recuperação da qualidade da água deste importante recurso hídrico.

Made available in DSpace on 2016-06-02T19:30:01Z (GMT). No. of bitstreams: 1 5864.pdf: 3534463 bytes, checksum: cd15fcfba13c323323c9b239d2f29ed8 (MD5) Previous issue date: 2014-03-06 / Financiadora de Estudos e Projetos / The study of diversity and productivity can contribute to understanding the functioning of Amazonian ecosystems as a whole and especially to the conservation of its aquatic biota, considered one of the richest in species on the planet. The present study aimed to analyze the course of three years the limnological characteristics of three floodplain lakes of the Madeira River in the area of influence of the Santo Antônio hydroelectric plant on the Madeira, in the region near to Porto Velho, Rondônia, with emphasis on the zooplankton community. Samples were quarterly covering the four major hydrological periods: low water, flood, high water and ebb over three years (2010-2013). Physical, chemical and biological variables of the lakes were collected and correlated with species composition, biomass and production of zooplankton. The zooplankton community was characterized by high species richness (195 taxa) and high degree of endemism for the group of Copepoda Calanoida. The results showed that the three lakes have eutrophic or mesotrophic characteristics. The highest values of density and biomass of zooplankton in the lake occurred Cujubim. The rotifers were numerically dominant, but the Copepoda dominated in biomass and secondary production in lakes Cuniã and San Miguel. There was little variability in secondary production of zooplankton, being slightly higher in the lake Cujubim with increased production of copepods and rotifers in this lake. The rainfall variation demarcated the occurrence of well-defined hydrological periods, directly affecting the hydrodynamics of this region, controlling population fluctuations of zooplankton, probably brought by the increased availability of resources on the Madeira River in the flood season, playing an important role in the organization of food webs, and how to link the transfer of matter and energy in food chains. / O estudo da diversidade e produtividade pode contribuir para o entendimento do funcionamento dos ecossistemas amazônicos como um todo e principalmente para a conservação da sua biota aquática, considerada uma das mais ricas em espécies no planeta. O presente estudo teve como objetivo analisar ao longo de três anos as características limnológicas de três lagos de várzea do rio Madeira na área de influência da Usina Hidroelétrica Santo Antônio do Madeira, na região próxima a Porto Velho, Rondônia, com ênfase na comunidade zooplanctônica. As amostragens foram trimestrais abrangendo os quatro períodos hidrológicos principais: Águas baixas, enchente, águas altas e vazante, ao longo de três anos (2010-2013). Foram coletadas variáveis físicas, químicas e biológicas dos lagos, correlacionando com a composição de espécies, além de determinadas a biomassa e a produção da comunidade zooplanctônica. A comunidade zooplanctônica foi caracterizada por elevada riqueza de espécies (195 táxons) e alto grau de endemismo para o grupo dos Copepoda Calanoida. Os resultados obtidos evidenciaram que os três lagos apresentam características mesotróficas ou eutróficas. Os maiores valores de densidade e biomassa da comunidade zooplanctônica ocorreram no lago Cujubim. Os Rotifera foram numericamente dominantes, mas os Copepoda dominaram em biomassa e produção secundária, nos lagos Cuniã e São Miguel. Houve pequena variabilidade na produção secundária da comunidade zooplanctônica, sendo ligeiramente superior no lago Cujubim, com maior a produção de Copepoda e Rotifera neste lago. A variação pluviométrica demarcou a ocorrência de períodos hidrológicos bem definidos, afetando diretamente a hidrodinâmica desta região, controlando flutuações populacionais da comunidade zooplanctônica, provavelmente pela maior disponibilidade de recursos trazidos do rio Madeira nos períodos de cheia, desempenhando papel importante na organização das teias tróficas, e como elo de transferência de matéria e energia nas cadeias alimentares.

Macroinvertebrate communities inhabiting an exotic, Myriophyllum spicatum, and a native, Heteranthera dubia macrophyte were studied from March 1999 to June 2000 in experimental ponds. Although macrophyte architecture explained some variation in macroinvertebrate abundance between the two macrophytes, most variation was explained by the sampling months. Total number of macroinvertebrates was found to be positively correlated with epiphyton biomass which differed significantly between the two plant types and among sampling months. Taxa richness did not vary between the two plant types. Chironomid larvae were the most abundant organisms and dominated by Apedilum elachistus on both plant communities. Annual production of five chironomid species was estimated by the size-frequency method. Production estimates (P) in g dry wt m-2 yr-1 of plant surface area for the predator Tanypodinae larvae were: Larsia decolarata, P= 0.77 and 0.67, Labrundinia virescens, P= 0.59 and 0.35 on M. spicatum and H. dubia, respectively. Larvae of Cricotopus sylvestris and Psectrocladius vernalis were collected from M. spicatum from March to mid-June. Production of C. sylvestris was found to be 0.46 g dry wt m-2, whereas it was 0.07 g dry wt m-2 for P. vernalis for this period. Apedilum elachistus exhibited the highest productivity: 9.9 g dry wt m-2 yr-1 of plant surface area on M. spicatum, and 8.5 g dry wt m-2 yr-1 on H. dubia. These production estimates are among the highest production values reported for a single species. Additionally, post-ovipositing development times for five chironomid species collected from Myriophyllum and Heteranthera were determined. Three different temperatures (15°, 20° and 25°C) were chosen to rear eggs under 12L: 12D photoperiod. Egg development times ranged between 1-4 days. Larval development times ranged from 44 days at 20°C for Tanypus neopunctipennis to as few as 9 days at 20°C for Larsia decolorata.

Intensive Landwirtschaft ist eine der allgegenwärtigsten anthropogenen Bedrohungen für aquatische Ökosysteme und beeinflusst sowohl die abiotischen als auch die biotischen Eigenschaften von Fließgewässerökosystemen. Diese resultieren aus der Vielzahl von Störungen, die mit Landnutzungsänderungen verbunden sind, wie z.B. Uferkahlschlag und dem damit verbundenen Verlust von allochthonem organischem Material und Beschattung, Nährstoff- und Pestizidkontamination, Feinsedimenteintrag durch Erosion und Oberflächenabfluss, sowie beeinträchtigte Hydromorphologie und damit verbundenem Verlust von vielfältigen Lebensräumen. Umfangreiche Literatur zu den Auswirkungen von Landwirtschaft auf einzelne Ökosystemkomponenten wie Makroinvertebraten, Biofilm oder Fischfauna existiert bereits, wobei der Schwerpunkt hier zumeist auf strukturellen Ansätzen oder einzelnen Ökosystemprozessen liegt. Allerdings haben nur wenige Studien umfassende Auswertungen angestellt, wie intensive Landwirtschaft die Funktion des gesamten aquatischen Ökosystems und die Wechselwirkungen zwischen den Ökosystemkomponenten beeinflusst. Um komplexe Effektmuster landwirtschaftlicher Stressoren auf Fließgewässerstruktur- und funktion sowie mechanistische Wirkzusammenhänge zwischen trophischen Ebenen besser zu verstehen wurden im Rahmen der vorliegenden Arbeit zwei Bäche die innerhalb landwirtschaftlicher Einzugsgebiete liegen und zwei bewaldete Referenzbäche im Harz, Sachsen-Anhalt, hinsichtlich ihrer physiko-chemischen Eigenschaften, der Menge und der Einträge von benthischem organischem Material, der Primärproduktion und organischen Kohlenstoffkreisläufen sowie der Sekundärproduktion von Makroinvertebraten und Fischen über einen Zeitraum von 12-17 Monate miteinander verglichen. Intensive Landwirtschaft hatte starke Auswirkungen auf die physiko-chemischen Eigenschaften der untersuchten Bachoberläufe. Wir ermittelten spezifische Leitfähigkeitswerte in landwirtschaftlich genutzten Bächen, welche die Konzentration gelöster Ionen in bewaldeten Referenzbächen um eine Größenordnung übertrafen. Die Konzentrationen von gelöstem anorganischem Stickstoff und löslichem reaktivem Phosphor waren in den landwirtschaftlichen Bächen im Durchschnitt viermal höher und der pH-Wert war im Durchschnitt eine Einheit niedriger als in den bewaldeten Bächen. Die Wassertemperatur war in landwirtschaftlich genutzten Bächen im Durchschnitt 3°C wärmer und zeigte höhere tageszeitliche Schwankungen. Der Eintrag von partikulärem organischem Material (POM) in die landwirtschaftlichen Bäche war ca. 30-mal niedriger als der Eintrag in die Referenzbäche, und die Menge an benthischem organischem Material (BOM) war in landwirtschaftlichen Bächen signifikant niedriger als in den Referenzbächen. Landwirtschaftliche Fließgewässer wiesen signifikant höhere Mengen an feinem benthischem organischem Material (FBOM) auf, hatten aber geringere Bestände an grobem benthischem organischem Material (CBOM) als die Referenzgewässer. Während in bewaldeten Fließgewässern die zeitliche Dynamik des BOM einem saisonalen Muster folgte, waren die Schwankungen in den landwirtschaftlichen Fließgewässern überwiegend stochastisch und durch anthropogene Aktivitäten, wie das Mähen der Uferrandstreifen, beeinflusst. Auch die Retention von POM war in landwirtschaftlich genutzten Bächen im Vergleich zu bewaldeten Bächen deutlich geringer, was auf eine geringere morphologische Komplexität und die größere hydrologische Variabilität, insbesondere auf die Abflussganglinien, zurückzuführen ist. Innerhalb des Experimentes zur Aufnahme von gelöstem organischem Kohlenstoff (DOC) war die Biofilmqualität in den landwirtschaftlichen Bächen ebenfalls höher. Interessanterweise zeigte jedoch der landwirtschaftliche Bach Hassel einen höheren Grad an Heterotrophie als der bewaldete Bach Wormsgraben. Da die biofilmspezifische DOC-Aufnahme im bewaldeten Bach nur 4 % der Gesamtaufnahme betrug, kann davon ausgegangen werden, dass die mikrobiell vermittelte Verarbeitung von Nährstoffen in der hyporheischen Zone den größten Anteil an der DOC-Aufnahme ausmachte. Vermutlich begünstigte die höhere Verweildauer und der bessere Austausch zwischen Oberflächenwasser und der hyporheischen Zone im bewaldeten Bach Wormsgraben die heterotrophe Nährstoffumsetzung im interstitiellen Porenraum. Die Bewertung der Makroinvertebraten-Gemeinschaft ergab, dass der Artenreichtum in landwirtschaftlichen Bächen im Vergleich zu bewaldeten Bächen um die Hälfte reduziert war. Die Biomasse, Dichte und Sekundärproduktion der Makroinvertebraten (Makroinvertebratensekundärproduktion, MSP) nahm jedoch entlang eines Gradienten der Ressourcenqualität und -quantität zu, mit höchster Produktivität im landwirtschaftlichen Bach Sauerbach, gefolgt vom landwirtschaftlichen Bach Getel und den bewaldeten Bächen Ochsenbach und Wormsgraben. Der Anstieg der MSP war hauptsächlich auf Zunahmen innerhalb der funktionellen Ernährungsgruppen der Sedimentfresser und Weidegänger zurückzuführen. Höhere MSP, Biomasse und Dichte korrelierten positiv mit niedrigeren N:P- und C:P-Verhältnissen des Biofilms und der Ressourcenmenge (höhere Biofilm-Zuwachsrate und Menge an krautiger Vegetation, Chlorophyll a-, TDN- (Summe an gelöstem Stickstoff), SRP- (gelöster reaktiver Phosphor) und POC- (Partikulärer organischer Kohlenstoff) Konzentrationen von Biofilm und Seston). Hohe Interaktionsstärken zwischen Zerkleinerern und grobpartikulärem organischem Material (CPOM) in landwirtschaftlichen Bächen deuteten auf eine Ressourcenlimitierung durch allochthones organisches Material hin. Da die Interaktionsstärken zwischen Weidegängern und Biofilm sowie zwischen feinpartikulärem organischem Material (FPOM) und Sammlern in landwirtschaftlichen Bächen deutlich geringer waren als in bewaldeten Bächen ist anzunehmen, dass die Gruppe der Zerkleinerer diese Limitation durch hohe funktionelle Plastizität und damit alternative Ressourcennutzung ausgleichen konnten. Die Analyse der Fischsekundärproduktion und Interaktionsstärken zwischen Fischen und ihrer Makroinvertebraten-Beute konnte zusätzlich zeigen, dass die landwirtschaftliche Flächennutzung zu einer starken Verschiebung des Fischartenspektrums führen und die Top-down Kontrolle der MSP durch Fische dadurch deutlich zurückgehen kann. Diese Ergebnisse zeigen, dass der Verlust der Ufervegetation und die übermäßige Nährstoffbelastung ökologische Nischen homogenisieren und hochproduktive Generalisten mit hoher Nahrungsplastizität begünstigten, die flexibel zwischen ubiquitären und stochastisch verfügbaren Nahrungsressourcen wechseln können. Insgesamt konnten wir mit dieser Studie darlegen, durch welche Mechanismen aus hoch-diversen, nährstoffbegrenzten, bewaldeten Bachoberläufen, die stark von terrestrischen Laubeinträgen abhängig sind, durch landwirtschaftliche Flächennutzung homogene, nährstoffbelastete und taxonomisch vereinfachte Bäche, mit einem hohen Maß an Autochthonie, werden können. Die gleichzeitige Analyse struktureller und funktioneller Indikatoren zeigte, dass die Landwirtschaft strukturelle Messgrößen wie den Artenreichtum beeinflusst, ohne dass es zu größeren Veränderungen in der Funktion kommen muss (ähnliche MSP im landwirtschaftlich genutzten Bach Getel im Vergleich zu bewaldeten Referenzbächen), und dass die Variabilität in der Funktion (Retention von organischem Material, Laubabbau) nicht automatisch die Informationen widerspiegelt, die die üblicherweise bewerteten chemischen oder biologischen strukturellen Messgrößen liefern. Die Ergebnisse dieser Arbeit zeigen deutlich, dass eine Kombination mehrerer struktureller und funktioneller Indikatoren entlang der Nahrungsnetzhierarchie erforderlich ist, um mechanistisch zu verstehen, wie intensive Landwirtschaft die Ökosysteme von Fließgewässern beeinflusst. So erlaubten z.B. nur die Informationen über die Qualität und Quantität der Primärproduktion, in Kombination mit strukturellen und funktionellen Informationen über die Makroinvertebratengemeinschaft, ein mechanistisches Verständnis darüber, wie landwirtschaftliche Stressoren die Produktivität mehrerer trophischer Ebenen des Nahrungsnetzes von Fließgewässern beeinflussen und damit auch wie diese Auswirkungen gemildert werden könnten. Diese Ergebnisse verdeutlichen die dringende Notwendigkeit, effektive und breite Gewässerrandstreifen zu erhalten oder zu errichten, um Sedimenteinträge durch Erosion- und Oberflächenabfluss zu verringern, sowie Einträge von Nährstoffen und Pestiziden zurückzuhalten, um eine verbesserte Vereinbarkeit von Landwirtschaft und Naturschutz zu erwirken. Diese Maßnahmen hätten eine positive Auswirkung auf Lebensraum- und Ressourcenvielfalt und schützen damit sowohl terrestrische als auch aquatische Ökosysteme und die damit verbundenen essentiellen Ökosystemdienstleistungen dieser Systeme.:Table of contents Table of contents 1 List of tables 5 List of figures 6 List of abbreviations and acronyms 8 Abstract 11 Zusammenfassung 14 1. General introduction 18 1.1 Forested headwater streams - the significance of aquatic-terrestrial coupling 18 1.2 Effects of agricultural land use on forested headwater streams 22 1.3 Integrating measures of ecosystem functioning in stream ecosystem assessment 24 1.4 Aims and objectives 28 1.5 Thesis outline 30 2. Chapter I: Agricultural land use alters temporal dynamics and the composition of organic matter in temperate headwater streams 31 2.1 Introduction 31 2.2 Methods 33 2.2.1 Study sites 33 2.2.2 Sampling of POM inputs and standing crops 37 2.2.3 Organic matter sample processing 37 2.2.4 Physical and chemical stream characteristics 38 2.2.5 C spiraling metrics 39 2.2.6 Litter decomposition 39 2.2.7 Data analyses 41 2.3 Results 43 2.3.1 Organic matter inputs 43 2.3.2 Benthic organic matter 46 2.3.3 Organic matter retention 52 2.3.4 Environmental drivers of BOM dynamics 55 2.3.5 Leaf litter decomposition 55 2.4 Discussion 57 2.4.1 Effects of agricultural land use on POM inputs and BOM dynamics 57 2.4.2 Organic matter retention 60 2.4.3 Organic matter processing 61 2.4.4 Ecosystem-level implications of altered OM dynamics 62 2.5 Conclusions 63 3. Chapter II: Biofilm-specific uptake does not explain differences in whole-stream DOC tracer uptake between a forest and an agricultural stream 64 3.1 Introduction 64 3.2 Methods 66 3.2.1 Site description 66 3.2.2 Stable isotope tDOC labeling 68 3.2.3 Experimental design 68 3.2.4 Sampling and analysis 69 3.2.5 Statistical analysis 72 3.3 Results 74 3.3.1 Stream characteristics 74 3.3.2 DOC uptake 75 3.3.3 Benthic biofilm attributes 79 3.4 Discussion 84 3.4.1 Mechanisms linking hydromorphology, benthic-biofilm uptake and whole-stream uptake 84 3.4.2 Comparison of whole-stream tDOC uptake with other studies 86 3.4.3 Benthic biofilm attributes 87 3.5 Conclusions 89 4. Chapter III: Resource supply and organismal dominance are associated with high secondary production in temperate agricultural streams 90 4.1 Introduction 90 4.2 Methods 93 4.2.1 Study sites 93 4.2.2 Macroinvertebrate sampling and processing 97 4.2.3 Macroinvertebrate secondary production (MSP) 97 4.2.4 Environmental characteristics of streams 98 4.2.5 Benthic organic matter 99 4.2.6 Biofilm biomass accrual and stoichiometry 99 4.2.7 Fish biomass 100 4.2.8 Ingestion rates and interaction strength 100 4.2.9 Data analyses 101 4.3 Results 104 4.3.1 Environmental characteristics of the study streams 104 4.3.2 Structural descriptors of the macroinvertebrate community 106 4.3.3 Macroinvertebrate secondary production (MSP) 107 4.3.4 Environmental drivers of MSP and biomass 109 4.3.5 Relationships between MSP and species richness and evenness 111 4.3.6 Consumer-resource interactions 111 4.4 Discussion 113 4.4.1 Environmental drivers of MSP and biomass 113 4.4.2 Biological mechanisms associated with MSP 116 4.4.3 Top-down vs. bottom-up control 118 4.5 Conclusion 120 5. General discussion 121 5.1 Environmental conditions 121 5.2 Allochthonous organic matter dynamics 122 5.3 Organic matter processing 124 5.4 Primary production 124 5.5 Drivers of macroinvertebrate secondary production 127 5.6 Fish community 128 6. General conclusion 132 7. Implications for the assessment of running water ecosystems 134 8. Outlook 137 References 139 Appendix 182 Chapter I 182 Chapter II 189 Supplemental methods 189 Chapter III 198 Acknowledgements 212 Curriculum vitae 215 List of publications 217 Publication output during thesis period 217 Further publications 218 Eidesstattliche Erklärung 219 / Intensive crop agriculture is one of the most ubiquitous and pervasive anthropogenic threats to aquatic ecosystems. Important agriculture-related pressures include riparian clearcutting and the associated loss of allochthonous organic matter inputs and shading, nutrient and pesticide contamination, fine sediment inputs due to erosion and run-off, increased surface runoff, flashier hydrographs as well as degraded geomorphology and habitat diversity. The multitude of stressors deriving from agricultural land use often produces concomitant effects on several groups of biological organism and associated functions. While effects on single ecosystem components such as macroinvertebrates, biofilm or fish fauna with primary focus on structural components or single ecosystem processes are well described, only few studies have compiled comprehensive data sets on how agriculture affects the functioning of the entire aquatic ecosystem and interactions among ecosystem components. Thus, this thesis aimed to fill this knowledge gap by comparing agricultural and forested reference streams regarding their physicochemical characteristics, organic matter standing stocks and inputs, primary production, organic carbon spiraling, DOC uptake rates as well as secondary production of macroinvertebrates and fish for a period of 12-17 months. Intensive agricultural land use had strong effects on the physico-chemistry of the studied headwater streams of the main study (two agricultural streams vs. two forested streams in the Harz mountains, Saxony-Anhalt). We ascertained specific conductivity values in agricultural streams that exceeded the ones measured in forested streams by an order of magnitude. Concentrations of dissolved inorganic nitrogen and soluble reactive phosphorus were on average four times higher and pH was on average one unit lower in agricultural streams than in forested streams. Water temperature was on average 3°C higher in agricultural streams and showed higher diurnal variations. Particulate organic matter (POM) inputs to forested streams were approx. 30-times higher than inputs into agricultural streams, and mean standing crops of total benthic organic matter (BOM) were significantly lower in agricultural streams than in forested streams. Agricultural streams had significantly higher standing crops of fine benthic organic matter (FBOM), but less coarse benthic organic matter (CBOM) than forested streams. While in forested streams temporal dynamics of organic matter standing stocks followed a seasonal pattern, variations were predominantly stochastic and influenced by anthropogenic activities such as stream margin mowing in agricultural streams. Also, the retention of POM was distinctly lower in agricultural compared to forested streams due to lower in-stream complexity and flashier hydrographs in agricultural streams indicating that agricultural streams are less efficient to retain organic matter, facilitating the loss of carbon to downstream sections of streams. Within the main study streams, biofilm accrual rates and chlorophyll a content were six and eight times higher, respectively, and biofilm N:P and C:P ratios were three times lower in agricultural than forested streams. In the dissolved organic carbon-uptake experiment (one agricultural stream vs. one forested stream), biofilm quality was similarly higher in the agricultural stream Hassel. Against expectations, the Hassel showed a higher level of heterotrophy than the forested stream Wormsgraben. However, the total and biofilm associated uptake of labeled leaf-leachate dissolved organic carbon (DOC) in the Hassel was six and two times higher than in the forested Wormsgraben, respectively. As the biofilm-specific uptake in the forested stream amounted to only 4% of the whole stream uptake, it seems that microbial-mediated processing of nutrients in the hyporheic zone is responsible for the largest proportion of DOC uptake. Presumably, the higher transient storage and the heterotrophic community resident in the interstitial pore space of the forested stream has a higher demand for labile DOC and hence, retained distinctly more DOC than in the agricultural stream, highlighting the importance of functional hyporheic zones for carbon spiraling. The macroinvertebrate community assessment revealed that species richness was reduced by half in agricultural compared to forested streams. Macroinvertebrate biomass, density, and secondary production (MSP), however, increased along a gradient of resource quality and quantity with highest productivity in the agricultural stream Sauerbach, followed by the agricultural stream Getel, and the forested streams Ochsenbach and Wormsgraben. The increase in MSP was mainly due to higher production within the functional feeding groups (FFGs) of gatherer/collectors and grazers. Higher MSP, biomass, and density correlated positively with lower biofilm N:P and C:P ratios and resource quantity (higher biofilm accrual rate and standing crops of riparian herbaceous vegetation, biofilm and seston chlorophyll a, total dissolved nitrogen, soluble reactive phosphorus, and particulate organic carbon concentrations). High interaction strengths between shredders and coarse particulate organic carbon (CPOM) in agricultural streams indicated a resource limitation of allochthonous organic matter, while this seemed to have no effect on macroinvertebrate productivity as interaction strengths between grazers and biofilm as well as between fine particulate organic carbon (FPOM) and gatherers were distinctly lower in agricultural than in forested streams. These findings show that the loss of riparian canopy and excess nutrient conditions homogenized ecological niches and favored highly productive non-insect generalist species with high feeding plasticity to switch flexibly between ubiquitous and stochastically available food resources. In addition, analyses of fish secondary production and interaction strengths between fish and their macroinvertebrate prey demonstrated that agriculture may cause a major shift in fish species community composition, resulting in a decline in fish top-down control on MSP. Overall, the presented results demonstrate that agriculture induces a shift from nutrient-limited forested headwaters dependent on detrital pathways and closely coupled to riparian subsidies with highly diverse macroinvertebrate communities to homogenous, nutrient contaminated and taxonomically simplified streams with high levels of autochthony. The simultaneous analysis of structural and functional indicators showed that agriculture affects structural measures of community composition such as species richness without major changes in process rates (similar level of macroinvertebrate secondary production in the agricultural stream Getel compared to forested streams) and that variability in function (organic matter retention, decomposition) does not automatically reflect the information provided by commonly assessed structural measures of communities. The results of this thesis clearly showed that a combination of multiple structural and functional indicators along the food web hierarchy is required to mechanistically understand how intensive agricultural land use affects stream ecosystems. For example, only the information on quality and quantity of primary production combined with structural and functional information on the macroinvertebrate community allowed to mechanistically understand how agricultural stressors affect the productivity of multiple trophic levels of the stream food web and thus, how these effects can be mitigated. Given that such mitigation measures would largely address excessive nutrient and sediment inputs, the loss of habitat heterogeneity and natural resource dynamics, the high relevance of riparian buffer zones known for their effective the retention of nutrients, erosional run-off and the provision of resource quantity and quality is evident. Consequently, there is an urgent need to preserve or restore effective riparian zones along stream networks aiding both terrestrial and aquatic ecosystems while integrating protection measures for other anthropogenic pressures such as habitat degradation and climate change.:Table of contents Table of contents 1 List of tables 5 List of figures 6 List of abbreviations and acronyms 8 Abstract 11 Zusammenfassung 14 1. General introduction 18 1.1 Forested headwater streams - the significance of aquatic-terrestrial coupling 18 1.2 Effects of agricultural land use on forested headwater streams 22 1.3 Integrating measures of ecosystem functioning in stream ecosystem assessment 24 1.4 Aims and objectives 28 1.5 Thesis outline 30 2. Chapter I: Agricultural land use alters temporal dynamics and the composition of organic matter in temperate headwater streams 31 2.1 Introduction 31 2.2 Methods 33 2.2.1 Study sites 33 2.2.2 Sampling of POM inputs and standing crops 37 2.2.3 Organic matter sample processing 37 2.2.4 Physical and chemical stream characteristics 38 2.2.5 C spiraling metrics 39 2.2.6 Litter decomposition 39 2.2.7 Data analyses 41 2.3 Results 43 2.3.1 Organic matter inputs 43 2.3.2 Benthic organic matter 46 2.3.3 Organic matter retention 52 2.3.4 Environmental drivers of BOM dynamics 55 2.3.5 Leaf litter decomposition 55 2.4 Discussion 57 2.4.1 Effects of agricultural land use on POM inputs and BOM dynamics 57 2.4.2 Organic matter retention 60 2.4.3 Organic matter processing 61 2.4.4 Ecosystem-level implications of altered OM dynamics 62 2.5 Conclusions 63 3. Chapter II: Biofilm-specific uptake does not explain differences in whole-stream DOC tracer uptake between a forest and an agricultural stream 64 3.1 Introduction 64 3.2 Methods 66 3.2.1 Site description 66 3.2.2 Stable isotope tDOC labeling 68 3.2.3 Experimental design 68 3.2.4 Sampling and analysis 69 3.2.5 Statistical analysis 72 3.3 Results 74 3.3.1 Stream characteristics 74 3.3.2 DOC uptake 75 3.3.3 Benthic biofilm attributes 79 3.4 Discussion 84 3.4.1 Mechanisms linking hydromorphology, benthic-biofilm uptake and whole-stream uptake 84 3.4.2 Comparison of whole-stream tDOC uptake with other studies 86 3.4.3 Benthic biofilm attributes 87 3.5 Conclusions 89 4. Chapter III: Resource supply and organismal dominance are associated with high secondary production in temperate agricultural streams 90 4.1 Introduction 90 4.2 Methods 93 4.2.1 Study sites 93 4.2.2 Macroinvertebrate sampling and processing 97 4.2.3 Macroinvertebrate secondary production (MSP) 97 4.2.4 Environmental characteristics of streams 98 4.2.5 Benthic organic matter 99 4.2.6 Biofilm biomass accrual and stoichiometry 99 4.2.7 Fish biomass 100 4.2.8 Ingestion rates and interaction strength 100 4.2.9 Data analyses 101 4.3 Results 104 4.3.1 Environmental characteristics of the study streams 104 4.3.2 Structural descriptors of the macroinvertebrate community 106 4.3.3 Macroinvertebrate secondary production (MSP) 107 4.3.4 Environmental drivers of MSP and biomass 109 4.3.5 Relationships between MSP and species richness and evenness 111 4.3.6 Consumer-resource interactions 111 4.4 Discussion 113 4.4.1 Environmental drivers of MSP and biomass 113 4.4.2 Biological mechanisms associated with MSP 116 4.4.3 Top-down vs. bottom-up control 118 4.5 Conclusion 120 5. General discussion 121 5.1 Environmental conditions 121 5.2 Allochthonous organic matter dynamics 122 5.3 Organic matter processing 124 5.4 Primary production 124 5.5 Drivers of macroinvertebrate secondary production 127 5.6 Fish community 128 6. General conclusion 132 7. Implications for the assessment of running water ecosystems 134 8. Outlook 137 References 139 Appendix 182 Chapter I 182 Chapter II 189 Supplemental methods 189 Chapter III 198 Acknowledgements 212 Curriculum vitae 215 List of publications 217 Publication output during thesis period 217 Further publications 218 Eidesstattliche Erklärung 219

Master of Science / Department of Biology / Keith B. Gido / Nonnative species represent a major threat to the continued persistence of native fishes globally, especially in the Colorado River Basin of western North America, where there are now more nonnative than native fishes. In the upper Gila River, a tributary of the Colorado, numerous nonnative fishes have established populations, and predation by these nonnatives has been linked to extirpation of native fishes under low-flow conditions at some locations. Historically, the upper Gila lacked a top piscivore, and it is unclear what mechanisms have allowed the establishment of nonnative piscivores and resultant extension in food chain length. To investigate the phenomenon of increased food chain length through nonnative introductions we explored the influence of autochthonous energy availability on nonnative predator abundance, food chain length, and abundance of other trophic levels. Predictions were that increased basal energy availability would lead to increased nonnative predator abundance and thus increased food chain length, based upon predictions from food web theory. Annual production and biomass of four trophic levels measured across six longitudinally-positioned sites were calculated between June 2008 and June 2009 to test these predictions. In addition, energy demand of trophic levels relative to energy supply was compared across sites using a quantitative food web approach, to evaluate energy limitation across trophic levels. Primary production was found to vary considerably across the upper Gila (1,677-16,276 kcal m-2 yr-1), but production and biomass of other trophic levels was not related to this gradient as predicted. In addition, food chain length demonstrated a marginally-significant negative relationship with primary production (R[superscript]2=0.42, d.f.=5, p=0.16), which was in contrast with predicted responses. These results suggest that energy availability does not appear to be a limiting factor to the production or biomass of consumers. The influence of other mechanisms on food chain length in the upper Gila River, in particular disturbance frequency and intensity, deserve further investigation.

O objetivo desta tese foi o estudo da variabilidade temporal, crescimento e produção do zooplâncton metazoário, com ênfase sobre estágios imaturos de copépodes, na região costeira de Ubatuba (SP, Brasil). Para tal, a comunidade zooplanctônica foi estudada durante as estações de verão e inverno em regime de dias alternados, para os anos de 2009 a 2011, através de coletas realizadas com redes de malha de 20 e 100 m. Índices ecológicos como densidade, diversidade e equitabilidade foram calculados. Os estágios imaturos de copépodes foram submetidos a experimentos de coortes artificiais em quatro classes de tamanho (50-80, 80-100, 100-150 e 150-200 m) para a determinação das taxas de crescimento de 14 táxons em diferentes estágios de desenvolvimento. A biomassa foi estimada através de equações de regressão comprimento-peso para o posterior cálculo da produção secundária. A incidência e possíveis efeitos de um protista alveolado parasita (Ellobiopsis sp.) sobre o crescimento de copépodes hospedeiros, com ênfase sobre a família Paracalanidae, também foi avaliada. A comunidade de copépodes esteve representada por 66 espécies e caracterizada por valores relativamente altos de diversidade e equitabilidade em relação aos demais trabalhos na plataforma interna da região sudeste do país. Os copépodes foram o grupo dominante, sendo que estágios naupliares foram os mais comuns para a rede de 20 m, enquanto que copepoditos juvenis dominaram para a rede de 100 m. A densidade do zooplâncton foi altamente variável, sendo os maiores valores registrados para o inverno de 2011 para a malha de 20 m (33.160 ± 23.136 org. m-3) e os menores para o inverno de 2009 para a malha de 100 m (5.393 ± 2.264 org. m-3). As famílias dominantes de copépodes foram Oithonidae, Oncaeidae, Paracalanidae e Acartiidae, sendo a primeira dominante também em termos de biomassa. Os estágios juvenis dos copépodes representaram uma biomassa entre 1,06 a 3,47 mg C m-3 para o inverno de 2010 e verão de 2009 respectivamente. Taxas de crescimento foram obtidas para sete táxons de Calanoida (0,41 ± 0,21 d-1), cinco de Cyclopoida (0,27 ± 0,17 d-1) e dois de Harpacticoida (0,31 ± 0,16 d-1). Os valores de crescimento foram semelhantes entre as diferentes classes de tamanho e as estações do ano, mas foram substancialmente diferentes entre as ordens, sendo geralmente maiores para os Calanoida. A produção média estimada para os estágios imaturos dos táxons dominantes de copépodes foi igual a 0,45 mg C m-3, valor conservativo por não contemplar as espécies de menor densidade e frequência. O crescimento de copépodes da família Paracalanidae, principalmente Parvocalanus crassirostris, foi afetado pelo protista parasita Ellobiopsis sp., uma vez que as fêmeas adultas infectadas foram significativamente menores do que as normais. Cerca de 5% das fêmeas da espécie estiveram infectadas pelo parasita, que provavelmente afeta o crescimento somático e reprodutivo de P. crassirostris, com efeitos ainda desconhecidos em termos de biomassa e produção. As taxas calculadas de crescimento e a produção são semelhantes às de outros trabalhos em regiões tropicais. A abordagem experimental através de coortes artificiais forneceu os primeiros resultados sobre o crescimento de estágios juvenis de copépodes para uma região subtropical do Atlântico Sul Ocidental e demonstrou que a concentração da clorofila-a não foi um fator limitante. Este é um dos poucos trabalhos a disponibilizar dados de crescimento, biomassa e produção de tais estágios em ecossistemas marinhos tropicais e que padroniza o método de coortes artificiais para obtenção do crescimento / This thesis aimed to evaluate the temporal variability of the metazoan zooplankton density, growth, and production, with emphasis on copepod immature stages in the coastal area of Ubatuba (São Paulo, Brazil). The zooplankton community was studied during summer and winter from 2009 to 2011, by means of sampling with 20 and 100 m mesh-sized nets. Ecological indexes such as density, diversity and evenness were calculated. Growth rates for 14 taxa of copepod juvenile stages were determined by the artificial cohort method, in four size classes and different developmental stages (50-80, 80-100, 100-150 and 150-200 m). Biomass was estimated by the use of length-weight regressions followed by secondary production estimates. The incidence and possible effects of the alveolate parasite Ellobiopsis sp. on the growth of the copepod hosts was also investigated, with emphasis on the Paracalanidae family. The copepod assemblage was represented by 66 species and displayed relatively high diversity and evenness, in comparison to other studies in the inner shelf of the Brazilian southeastern coast. Copepod was the dominant group; nauplii in the 20 m net, and juvenile copepodids in the 100 m net. The zooplankton density was highly variable: the highest densities occurred during winter 2011 in the 20 m samples (33,160 ± 23,136 org. m-3) and the lowest for the winter 2009 in the 100 m samples (5,393 ± 2,264 org. m-3). The dominant copepod families were Oithonidae, Oncaeidae, Paracalanidae and Acartiidae, the former being the main taxa in terms of biomass as well. Juvenile copepod biomass varied between 1.06 and 3.47 mg C m-3 in the winter 2010 and summer 2009, respectively. Growth rates were recorded for seven Calanoida (0.41 ± 0.21 d-1), five Cyclopoida (0.27 ± 0.17 d-1) and two Harpacticoida (0.31 ± 0.16 d-1) taxa. Growth values were similar between the different size classes, seasons and years, but were substantially different between copepod orders (higher rates for the Calanoida). The mean production for all immature copepod stages was 0.45 mg C m-3, a conservative value, since rare species were not accounted for. The growth of the Paracalanidae copepod Parvocalanus crassirostris, was affected by the parasite protist Ellobiopsis sp., since infected adult females were significantly smaller than normal individuals. About 5% of adult females were infected by the parasite, which probably reduced somatic and reproductive growth of P. crassirostris, with potential consequences for biomass accumulation and, consequently, production. Growth and production rates were similar to those found in other studies carried out in tropical regions. The artificial cohort method has been applied here for the first time on the tropical and subtropical Southwest Atlantic, where clorophyl-a concentration was not considered a limiting factor for growth rates. This is one of the few studies providing data on growth, biomass and production for copepod juvenile stages in tropical marine ecosystems and standardizing the artificial cohort method to measure the growth rates

O principal objetivo deste trabalho foi avaliar a dinâmica populacional dos cladóceros e apendiculários em uma estação fixa ao largo de Ubatuba (SP, Brasil). As amostras de zooplâncton foram coletadas mensalmente, de julho de 2005 a dezembro de 2008, com uma rede de malha de 200 ?m. Os apendiculários e os cladóceros foram identificados, classificados em estágios, contados e medidos. Ambos os grupos taxonômicos tiveram maiores densidades nas camadas superficiais, principalmente quando a coluna de água estava estratificada devido às intrusões de fundo da Água Central do Atlântico Sul (ACAS). A temperatura foi a principal variável influenciando na distribuição de Penilia avirostris e dos apendiculários, enquanto para Pseudevadne tergestina e Evadne spinifera a salinidade foi um melhor indicador da variabilidade temporal. A pressão de predação e o alimento disponível também pareceram controlar a distribuição dos apendiculários e dos cladóceros. Indivíduos gamogênicos ocorreram associados aos máximos de abundância; eles foram raros e pouco abundantes, indicando que na costa de Ubatuba os cladóceros podem se propagar apenas por partenogênese durante todo o ano. Os apendiculários tiveram uma produção anual média de ~70% em relação à dos copépodes, confirmando a importância dos apendiculários no fluxo de carbono em regiões costeiras tropicais e subtropicais. / This work aimed to evaluate the population dynamics of cladocerans and appendicularians at a fixed station off Ubatuba (state of São Paulo, Brazil). Zooplankton samples were monthly collected, from July 2005 through December 2008, with a 200 ?m mesh net. Appendicularians and cladocerans were identified, classified into stages, counted and measured. Both taxonomic groups had higher densities at upper layers, especially when the water column was stratified due to bottom intrusions of the South Atlantic Central Water (SACW). Temperature was the main parameter influencing on the distribution of Penilia avirostris and appendicularians, whereas salinity was the principal regulating parameter of Pseudevadne tergestina and Evadne spinifera population dynamics. Predation pressure and avaiable food also seemed to control the distribution of appendicularians and cladocerans. Gamogenic individuals occurred associated with abundance maxima; they were rare and had low abundances, which indicates that in Ubatuba cladocerans may propagate only through parthenogenesis during the entire year. Appendicularians had an annual mean production ~70% of that of copepods, which confirms that appendicularians play a key role in the carbon flow in coastal subtropical and tropical regions