The aim of this study was investigate if increasing total organic carbon (TOC) affects the growth rate and biomass of perch (Perca fluviatilis) and biomass of roach (Rutilus rutilus). The ongoing climate change affects the climate by increasing annual mean temperature and precipitation. The runoff to surface waters will increase, which also has the consequence that the export of terrestrial organic matter (TOM) and nutrients to surface waters will increase. Increasing of TOM into the surface waters make it darker, i.e. brownification of the water. This brownification of surface water affects the amount of available light for benthic algae causing the benthic primary production to decrease. As the benthic primary production decreases also whole lake ecosystem productivity decreases. The impact on fish biomass and production of fish were studied in five small lakes in Sweden. Lake morphology, water chemistry and fish community characteristics were sampled. A subset of perch from the catch was selected to determine age and growth. Data from age determination was then used to calculate the size dependent growth and production of perch in each lake. Total fish biomass and biomass of perch and roach was negatively affected by TOC and yearly biomass production of perch was lower in lakes with higher TOC. Thus, climate change may at least in small forest lakes lead to lower production and biomass of fish in the future.

Phenotypic plasticity in Eurasian perch (Perca fluviatilis) can be driven by a trade-off for ecological specialisation to littoral and pelagic resources. Previous studies on perch have found that this specialisation can have different effects on linkage between the littoral and pelagic food web depending on water transparency. In this study I aimed to answer how foraging efficiency and prey preference of phenotypic divergent perch are affected by high and low water transparency, and the presence of a predator in a series of aquarium experiments. Two different phenotypes of perch were kept in littoral and pelagic environments in the lab. By presenting perch with Daphnia sp. and Ephemeroptera, either separately or combined. I found that in clear water the littoral and pelagic phenotypes were comparatively more efficient on resources that were representative of their habitats (Ephemeroptera and Daphnia, respectively) and that both phenotypes prefer Ephemeroptera over Daphnia. In low visibility the differences in foraging efficiency between phenotypes when feeding on Daphnia disappeared but remained similar to clear water when feeding on Ephemeroptera. When vision was constrained littoral and pelagic perch showed no sign of prey preferences. In the presence of a predator the difference in foraging efficiency between the phenotypes, and also prey preference disappeared. I found that littoral phenotypes interacted more with other group members than did pelagic phenotypes, when foraging on littoral prey. And for perch in general, when foraging for Daphnia the interaction among group members was markedly reduced compared to when foraging for Ephemeroptera. In this study I show that morphological adaptation and prey choice is affected by visibility and predation. I also give suggestions how and argue why this can affect linkage of food webs and the community composition in littoral and pelagic habitats.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2009. / Härtill 5 uppsatser.

O presente estudo foi baseado na ocorrência, análises morfométricas, craniométricas e conteúdo estomacal de cetáceos odontocetes encontrados mortos em praias do sul do Estado de São Paulo (Ilha Comprida e Marujá) e norte do Estado do Paraná (Deserta), no período de abril de 1986 à abril de 1988. Para a espécie mais abundante estimou-se também a idade dos indivíduos pelo número de anéis na camada de dentina. Encontrou-se 100 animais compreendidos em 7 gêneros e 7 espécies pertencentes a 3 famílias. Para a região são caracterizadas pela primeira vez, Delphinus delphis (n=13), Stenella frontalis (n=3) , Kogia breviceps (n=1) e Globicephala macrorhynchus (n=1). Destas, para o litoral e São Paulo são novas S. frontalis e G. macrorhynchus, sendo esta última também descrita pela primeira vez para águas ocidentais do Atlântico Sul. Para o litoral do Estado do Paraná são todas ocorrências novas, com exceção de Sotalia fluviatilis. Esta última foi a espécie mais abundante (n=58) , seguida por Pontoporia blainvillei (n=21). Também foi encontrada a espécie Tursiops gephyreus (n=2) além de 1 delfinídeo não identificado. A ocorrência total dessas espécies seguiu um padrão pouco definido ao longo do ano, ocorrendo em maior número nos meses de inverno e verão. Para a espécie mais abundante, S. fluviatilis alguns dos parâmetros de crescimento foram estimados baseando-se em equações que descrevem relações interespecíficas desses parâmetros. Animais com 6 ou mais anéis foram classificados como maduros fisicamente. Construiu-se uma curva de crescimento a mão livre para a espécie, baseando-se em alguns dos dados fornecidos pelas equações e dados obtidos dos próprios exemplares como número de anéis dos dentes e comprimentos dos corpos; o método de von Bertalanffy para ajuste da curva de crescimento não mostrou-se satisfatório para todas as fases do crescimento da espécie. Ainda para essa espécie analisou-se 5 componentes funcionais do crânio dos exemplares encontrados, obtendo-se 6 anéis para a estabilização do crescimento desses componentes, com excessão do aparato alimentar que atingiu o patamar com 8 anéis. A análise da dieta alimentar dessa espécie mostrou a ocorrência de espécies de peixes demersais pelágicas de superfície comuns na região costeira, sendo a família Sciaenidae a mais abundante. Bicos de lulas pertencentes a 2 ou 3 espécies também foram encontrados em 100% dos estômagos analisados. Encontrou-se em um Estômago camarões pertencentes à espécie Penaeus brasiliensis. Parasitas estomacais pertencentes à família Anisakidae foram encontrados em 28,6% dos estômagos, além de mesma frequência para isópodos parasitas de brânquias de peixes. A maioria dos animais encontrados. Possivelmente foram mortos em redes de pesca na região costeira adjacente às praias estudadas. / The occurrence, morphometric and craniometric data and stomach contents of odontoceti cetaceans found in the south coast of São Paulo State and north coast of Paraná State (Ilha Comprida, Marujá and Deserta beaches) from April, 1986 to April, 1988 were analysed in this study. For the most abundant species we estimated the individual age by reading growth layers in the dentine. We found 100 animaIs belonging to 7 genera, 7 species and 3 famiIies. The first records for this region were: Delphinus delphis (n=13), Stenella frontalis (n=3). Kogia breviceps (n=1), and Globicephala macrorhynchus (n=1). The first ones for the coast of São Paulo State were: S. frontalis and G. macrorhynchus. This Iast species was also first described for the southwestern Atlantic. AlI of the species were new records for the coasts of Paraná State except S. fluviatilis. This Iast one was the most abundant species (n=58), followed by Pontoporia blainvillei (n=21). We also encountered Tursiops gephyreus (n=2) and an unidentified delfinid. There was little seasonal pattern in the total occurrence of the animals with a small increase in their abundance during the winter and summer seasons. For the most abundant species, Sotalis fluviatilis, we estimated some growth parameters using published equations which describe the interspecific relationships of these parameters. Physical maturity was considered in animals with for more dental layers. A growth curve was drawn by eye, using data obtained the from some of the above equations and data obtained from individuaIs analysed in this study, such as dental layers and total length; a growth curve by von Bertalanffy\'s method did not fit well. The species plateau development of 5 skull functional components for this showed 6 dental layers for the attainment of adult plateau except for the feeding apparatus which stops growing at 8 dental layers. The diet of S. fluviatilis consisted mainly of demersal and superficial pelagic common fishes found in the Brazilian southeastern coast. The Sciaenidae family was the most abundant. Beaks of squids belonging to 2 or 3 especies were found in all stomach contents analysed; we also encountered shrimps in one stomach content. Stomach parasites belonging to the Anisakidae family were found in 28,6% of the stomachs with the same frequency of fish gill parasite isopods. Most of the cetaceans were probably captured accidentally with gillnets in adjacent waters of the studied beaches.

O presente estudo foi baseado na ocorrência, análises morfométricas, craniométricas e conteúdo estomacal de cetáceos odontocetes encontrados mortos em praias do sul do Estado de São Paulo (Ilha Comprida e Marujá) e norte do Estado do Paraná (Deserta), no período de abril de 1986 à abril de 1988. Para a espécie mais abundante estimou-se também a idade dos indivíduos pelo número de anéis na camada de dentina. Encontrou-se 100 animais compreendidos em 7 gêneros e 7 espécies pertencentes a 3 famílias. Para a região são caracterizadas pela primeira vez, Delphinus delphis (n=13), Stenella frontalis (n=3) , Kogia breviceps (n=1) e Globicephala macrorhynchus (n=1). Destas, para o litoral e São Paulo são novas S. frontalis e G. macrorhynchus, sendo esta última também descrita pela primeira vez para águas ocidentais do Atlântico Sul. Para o litoral do Estado do Paraná são todas ocorrências novas, com exceção de Sotalia fluviatilis. Esta última foi a espécie mais abundante (n=58) , seguida por Pontoporia blainvillei (n=21). Também foi encontrada a espécie Tursiops gephyreus (n=2) além de 1 delfinídeo não identificado. A ocorrência total dessas espécies seguiu um padrão pouco definido ao longo do ano, ocorrendo em maior número nos meses de inverno e verão. Para a espécie mais abundante, S. fluviatilis alguns dos parâmetros de crescimento foram estimados baseando-se em equações que descrevem relações interespecíficas desses parâmetros. Animais com 6 ou mais anéis foram classificados como maduros fisicamente. Construiu-se uma curva de crescimento a mão livre para a espécie, baseando-se em alguns dos dados fornecidos pelas equações e dados obtidos dos próprios exemplares como número de anéis dos dentes e comprimentos dos corpos; o método de von Bertalanffy para ajuste da curva de crescimento não mostrou-se satisfatório para todas as fases do crescimento da espécie. Ainda para essa espécie analisou-se 5 componentes funcionais do crânio dos exemplares encontrados, obtendo-se 6 anéis para a estabilização do crescimento desses componentes, com excessão do aparato alimentar que atingiu o patamar com 8 anéis. A análise da dieta alimentar dessa espécie mostrou a ocorrência de espécies de peixes demersais pelágicas de superfície comuns na região costeira, sendo a família Sciaenidae a mais abundante. Bicos de lulas pertencentes a 2 ou 3 espécies também foram encontrados em 100% dos estômagos analisados. Encontrou-se em um Estômago camarões pertencentes à espécie Penaeus brasiliensis. Parasitas estomacais pertencentes à família Anisakidae foram encontrados em 28,6% dos estômagos, além de mesma frequência para isópodos parasitas de brânquias de peixes. A maioria dos animais encontrados. Possivelmente foram mortos em redes de pesca na região costeira adjacente às praias estudadas. / The occurrence, morphometric and craniometric data and stomach contents of odontoceti cetaceans found in the south coast of São Paulo State and north coast of Paraná State (Ilha Comprida, Marujá and Deserta beaches) from April, 1986 to April, 1988 were analysed in this study. For the most abundant species we estimated the individual age by reading growth layers in the dentine. We found 100 animaIs belonging to 7 genera, 7 species and 3 famiIies. The first records for this region were: Delphinus delphis (n=13), Stenella frontalis (n=3). Kogia breviceps (n=1), and Globicephala macrorhynchus (n=1). The first ones for the coast of São Paulo State were: S. frontalis and G. macrorhynchus. This Iast species was also first described for the southwestern Atlantic. AlI of the species were new records for the coasts of Paraná State except S. fluviatilis. This Iast one was the most abundant species (n=58), followed by Pontoporia blainvillei (n=21). We also encountered Tursiops gephyreus (n=2) and an unidentified delfinid. There was little seasonal pattern in the total occurrence of the animals with a small increase in their abundance during the winter and summer seasons. For the most abundant species, Sotalis fluviatilis, we estimated some growth parameters using published equations which describe the interspecific relationships of these parameters. Physical maturity was considered in animals with for more dental layers. A growth curve was drawn by eye, using data obtained the from some of the above equations and data obtained from individuaIs analysed in this study, such as dental layers and total length; a growth curve by von Bertalanffy\'s method did not fit well. The species plateau development of 5 skull functional components for this showed 6 dental layers for the attainment of adult plateau except for the feeding apparatus which stops growing at 8 dental layers. The diet of S. fluviatilis consisted mainly of demersal and superficial pelagic common fishes found in the Brazilian southeastern coast. The Sciaenidae family was the most abundant. Beaks of squids belonging to 2 or 3 especies were found in all stomach contents analysed; we also encountered shrimps in one stomach content. Stomach parasites belonging to the Anisakidae family were found in 28,6% of the stomachs with the same frequency of fish gill parasite isopods. Most of the cetaceans were probably captured accidentally with gillnets in adjacent waters of the studied beaches.

L’amélioration des performances de reproduction des poissons d’élevage nécessite de déterminer les facteurs intrinsèques et extrinsèques influençant la qualité des gamètes d’une part, et de définir des paramètres fiables permettant de prédire les performances de reproduction d’autre part. Notre objectif est donc de comprendre le déterminisme multifactoriel de la reproduction chez la perche commune, Perca fluviatilis. Quatre facteurs nutritionnels (type d’aliment et taux de rationnement distribués lors des phases d’induction et de vernalisation) et 3 facteurs populationnels (poids initial, origine géographique, niveau de domestication) ont été testés. Une différence de réponse entre les sexes a été observée. Le type d’aliment distribué en vernalisation et le poids initial ont modifié l’état général des femelles. Les mâles ont plutôt été sensibles aux taux de rationnement et à l’origine géographique. L’étude des performances de reproduction a montré que le taux de ponte était sous l’influence de l’interaction entre le type d’aliment distribué en induction et en vernalisation, tandis que l’origine géographique a modulé la date de ponte. La régulation des performances de reproduction est donc un mécanisme complexe sous l’influence simultanée de plusieurs facteurs. La seconde partie de ce travail concerne la recherche de marqueurs prédictifs de la qualité des ovules. Nous avons d’abord montré que peu de paramètres morpho-anatomiques des pontes ou ovules sont des prédicateurs fiables. Cependant, l’analyse protéomique a permis de mettre en évidence plusieurs protéines exprimées différemment selon la qualité des pontes, pouvant jouer le rôle de biomarqueurs de qualité des ovules / Improving fish reproduction in breeding conditions implies to understand intrinsic and extrinsic factors influencing gametes quality on the one hand and to define relevant parameters allowing the prediction of fish reproductive performance on the other hand. Our goal was thus to understand the multifactorial determinism of the common perch (Perca fluviatilis) reproduction. Four nutritional factors (type of food and rate of rationing used either during the induction or vernalization phases) and 3 populational factors (initial weight, geographic origin and domestication level of breeders) have been tested. Data show different responses between females and males. type of food during wintering phase and initial broodstock weigh modified female condition. Males have been sensitive to rationing during wintering phase as well as geographical origin. Data show also that spawning rate was under the influence of interaction between kind of food during wintering phase and induction whereas geographical origin modulated the spawning date. The regulation of the performance reproduction is also a complex mechanism influenced by several factors. The second part of this work consisted on the research of parameters potentially predictive of ova quality. Firstly, our work shows that morphometric parameters measured before the fertilization are poorly relevant to predict reproductive performance. However, the proteomic analysis of several spawn allowed us to highlight proteins differently expressed according to the spawn quality, such proteins could be ova quality biomarkers

Top predators in aquatic ecosystems often have strong top-down effects on the ecosystem. Northern pike (Esox lucius) has been documented to cause whitefish (Coregonus lavaretus) populations to diverge into different ecomorphs. This can facilitate piscivory in other predators as a novel resource becomes available to them in the form of dwarf whitefish. The aim of this study is to examine whether the presence of pike causes Eurasian perch (Perca fluviatilis) to shift their diet from insectivory to piscivory, and whether this is directly driven by whitefish polymorphism. Stomach contents of 147 perch from lakes with and without pikes were analyzed. The results show that the presence of pike has a clear influence on the diet of the perch. In lakes without pike, perch are mostly insectivorous, and in lakes with pike, they are mostly piscivorous. This diet shift appears to be driven by whitefish availability, as a majority of the diet of perch in pike lakes consisted of whitefish, while none of the fish eaten by perch in non-pike lakes was whitefish. In addition, the results showed that perch undergo the diet shift from insectivory to piscivory at a smaller size when coexisting with pike. This study can be added to the growing body of evidence for the ecological significance of pike.

Biocide-based antifouling (AF) paints are the most common method for preventing biofouling, i.e. the growth of algae, barnacles and other organisms on boat hulls. AF paints for leisure boats are predominantly based on copper (Cu) as the main biocide, with zinc (Zn) present as a pigment and stabilizer. Both metals are released from the paint matrix into the water column, leading to contamination of marinas which typically have only limited water exchange. Thus, the aim of this PhD thesis was to describe the use of AF paints in different regions in Sweden, as well as the associated environmental consequences with regard to contamination of the environment and toxicity to non-target aquatic snails. Using a recently developed X-ray fluorescence application, high levels of Cu were detected on boats moored in freshwaters, despite a more than 20-year-old ban, as well as high levels of tin (Sn) on 10 % of the boats, indicating the presence of (old) tributyltin paints (TBT), which might pose an environmental risk and a health hazard for people performing the paint scraping (paper 1). In addition, very high levels of Cu and Zn were measured in the biofouling material collected from the boat hulls, and this is problematic because the biofouling is commonly disposed of on the soil in boatyards at the end of each season. No difference was found in the amount of biofouling on boats coated with Cu or biocide-free paints, which implies that Cu might be currently overused in areas of low salinity and low barnacle density (paper 2). This work also introduces the use of a new species for ecotoxicological field experiments, the snail Theodoxus fluviatilis. Chronic field experiments (paper 3) revealed 6-fold increases in snail mortality, negative growth and up to 67-fold decreased reproduction in marinas, compared to areas not impacted by boating (‘reference areas’). Moreover, a higher prevalence of snails with histopathological alterations (e.g. necrosis of gills, gonads, midgut gland and parasite infestation, among others) was observed in the marinas, compared to the reference areas (paper 4). Statistical modelling indicated that the majority of the toxic effects were best predicted by the metals, most likely originating from AF paints. The results presented in this thesis depict some important aspects of AF paint use in brackish water and highlight the necessity of implementing a suitable management practice for the heavily contaminated biofouling waste in order to minimize the risk to soils. In addition, the evidence of toxicity to snails in marinas can be used as a basis to increase the public understanding of the impact of recreational boating and encourage people to choose less toxic alternatives to AF paints. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.</p>

The Lower Karori Reservoir (LKR) is a small, monomictic lake of 2.34 ha situated in the Karori Wildlife Sanctuary (KWS), Wellington. Over the past decade cyanobacterial blooms have become a common occurrence in this water body. In 2005 Anabaena planktonica was detected for the first time in the LKR and this species now forms dense blooms during summer. These blooms are problematic as they reduce aesthetic appeal and have resulted in odour problems for visitors to this high profile wildlife sanctuary. The objectives of this study were to identify key physical, chemical and biological variables influencing phytoplankton dynamics in the LKR and to use ecological models to investigate plausible management options. The key parameters investigated, that may cause bloom formation were; summer stratification, high nutrient levels, and the food web effects of a large population of European perch (Perca fluviatilis). High resolution sampling was carried out every six hours over a 72 hour period during pre-bloom, bloom and post-bloom periods in 2006/7 to elucidate short term temporal and spatial variations in biological and physico-chemical parameters. Quantitative polymerase chain reaction (QPCR) was used to enumerate A. planktonica populations, allowing a large number of samples to be simultaneously evaluated. Algal densities were also estimated using conventional phytoplankton enumeration and chlorophyll a analysis. Water samples were collected for nutrient analysis at discrete depths and profiles were taken for temperature, dissolved oxygen and photosynthetic active radiation. Secchi depth and pH were also measured. Weekly or fortnightly phytoplankton and zooplankton samples and physical variables have been collected at LKR since September 2005 as part of an independent sampling program carried out by the KWS, Waikato University and Cawthron Institute. In this project the 2-year data set was used to assist with analysis of lake processes and for validation of the hydrodynamic-ecological model DYRESM-CAEDYM. Between 12 and 15 February, 2007, electric fishing was undertaken within the LKR. A total of 3,946 P. fluviatilis were removed and the effects on phytoplankton and zooplankton concentrations were investigated. To increase knowledge of the physiology of A. planktonica, laboratory experiments were undertaken using cultures subjected to a range of different light intensities and temperature regimes The phytoplankton assemblage of the LKR shows very distinct temporal variations. Summer stratification occurred in the LKR for ~4 months each summer. During these periods A. planktonica comprised up to 99.9% of the surface phytoplankton population. During isothermy chlorophytes, bacillariophytes and small flagellated dinophytes are co-dominant in the phytoplankton assemblage. The results of the QPCR showed distinct diurnal vertical movement of A. planktonica, with the highest cell concentrations occurring at 1900 hours at the surface. Ammonium (NH4-N) is the dominant species of inorganic nitrogen during periods of stratification, while nitrate (NO3-N) is generally dominant during times of isothermy. Phosphate concentrations at surface and depth remained at low levels throughout the sampling period. The large surface populations of A. planktonica, are probably responsible for the elevated total nitrogen concentrations in surface waters during stratified periods. There appeared to be some short term effects of the P. fluviatilis removal with an increase in large crustaceans (e.g., Daphnia sp.) and a reduction in A. planktonica densities observed in the months following the P. fluviatilis removal. Only a small proportion of the total P. fluviatilis population was removed and it is unlikely that the effects will be long-lasting without subsequent removal steps. However, it seems likely that P. fluviatilis is one of the factors contributing to cyanobacterial blooms and management of this fish species should be considered in future lake restoration plans. Growth experiments indicated A. planktonica grow over a wide range of light intensities and temperatures, although highest growth rates were generally associated with higher temperatures (25 C) and light intensities (60 - 140 μmol m-2 s-1). Ecological and hydrodynamic trends within the LKR over a two year period were simulated with adequate success using the model DYRESM-CAEDYM. Management scenarios simulated using DYRESM-CAEDYM suggest implementation of an artificial destratification system in the LKR may be the most practical and effective means of controlling A. planktonica blooms. The addition of an artificial aeration system emitting air at a rate of approximately 50 l-1 s-1 should result in an isothermal system. Without summer stratification some of the physiological features of A. planktonica (e.g., buoyancy regulation and nitrogen-fixation) that give it a competitive advantage over other phytoplankton species will be reduced.

Individuals within a single population can vary widely in their phenotype e.g. in their body shape. These differences are an important source of biodiversity and they can precede evolutionary divergence within a population. In this thesis we use the biological invasion of the zebra mussels into Swedish lakes to investigate which processes create or maintain phenotypic diversity within populations of the two native fish species perch and roach and the mussel itself. Both fishes have specially adapted body shapes that depend on whether they feed in the near-shore or open-water habitat of lakes. This habitat-specific divergence was more pronounced in lakes with zebra mussels, probably because resources in both habitats were in higher supply due to the mussels’ effects on the lakes. Divergence in perch body shapes between habitats was also higher in lakes with a higher water clarity, suggesting that visual conditions can affect the resource use and thus also the expression of a habitat-specific body shape. When investigating the diversity of body shapes in the mussel itself we found that mussels from one lake changed their shell shape when exposed to different predators: fish predators induced a more elongated shell shape while crayfish predators induced a rounder shell. These specific shell shapes probably serve as two alternative predator defenses protecting the mussel from predation. We conclude that the availability and use of distinct resources is an important source of diversity within populations. Abiotic conditions can play a previously underappreciated role by promoting or impairing the use of the distinct resources thus affecting the divergence. The diversity of shell shapes we found in the zebra mussels complements our study by demonstrating that not only consumer responses to resources but also resources’ responses to predators can generate phenotypic diversity.