Studies of growth rates of some freshwater cryptophyte algae

Cryptophytes are free-living unicellular algae which are important for the productivity and food chain Dynamics of temperate lakes. This study provides fundamental information on the ecophysiology of two freshwater cryptophytes of different cell size, mainly in terms of growth and related factors. This thesis comprises of six chapters, three of which describe light or light-and-temperature experiments with small-scale batch cultures (Chapters. 2 to 4), one depicts a larger scale laboratory experiment simulating natural conditions (Chapter 5) and the two last (Chapters 6 and 7) are based on short-term investigations in situ. The effects of light and temperature on nutrient-saturated growth and cellular composition (chlorophyll a, proteins, carbohydrates) were studied in batch cultures. With the help of mathematical models, the physiological basis for interspecific differences of growth response was determined (Chapter 2). The cryptophyte strain L315 appeared to be a cold-water species as its optimum temperature was ca. 19°C. The strain L485 was more adapted to warm-water conditions with its optimum of ca. 24.5 °C. In respect of their growth response to irradiance, L485 can be said to be a stenotopic and L315 a eurytopic strain, as L485 shows photoinhibition soon after saturation point, whereas L315 tolerates a much wider range of irradiance. The role of changes in cellular composition is discussed. In order to explain the observed growth differences the effects of light and temperature on gross photosynthesis, respiration and hence net productivity were studied (Chapter 3). The observed respiration/photosynthesis ratios were high, as in L485 and L315 respiration accounted for 17-77 % and 14-81 % of gross photosynthesis, respectively. Under optimum conditions the respiration/Pmax for L485 was 17 % and for L315 58 %. The response of cryptophytes to chromatic light was studied by means of quantitative epifluorescence microscopy and it was found that in comparison to blue-green algae cryptophytes L485 and L315 do not gain such great adaptational advantages in terms of growth by chromatic adaptation (Chapter 4). The modest role of chromatic adaptation is discussed. The role of diel vertical migrations (DVM) in the growth of cryptophytes was studied in 4 m tall experimental columns (Chapter 5). Results revealed that by migrating into cooler, nutrient rich. hypolimnion flagellated cryptophytes can increase their growth rate under conditions where resources (light and nutrients) are spatially separated for prolonged time periods. This study also emphasizes the need for more detailed DVM studies in situ. Finally, the pattern and timing of nuclear and cellular division in two Cryptomonas species in situ was studied by means of mitotic index technique (Chapter 6) and DNA quantification (Chapter 7). The nuclear division of Cryptomonas L485 (Chapter 6) appeared to be well phased, but as in this division pattern mitosis and cytokinesis were totally overlapping, it was impossible to calculate in situ growth rates. Field observations (Chapter 7) revealed that DNA quantification by means of epifluorescence microscopy is possible from a natural cryptophyte population, but as the Cryptomonas sp. population under scrutiny was not well phased, growth rate calculation could not be carried out. The survival strategies of Cryptophytes L485 and L315 in terms of r vs. K strategies are discussed in Chapter 8. It is pointed out that, although the habitats occupied by these strains as well as some of their morphological and physiological features indicate that L485 is probably a r-strategist and L315 a K-strategist, it is not possible to draw final conclusions on the basis of this study. Light and temperature, i.e. the factors mostly studied in this thesis, are presumably not the environmental factors of greatest selective importance for these cryptophytes in natural competitive situations

Urban Wetlands: A Review on Ecological and Cultural Values

Wetlands are a critical part of natural environments that offer a wide range of ecosystem services. In urban areas, wetlands contribute to the livability of cities through improving the water quality, carbon sequestration, providing habitats for wildlife species, reducing the effects of urban heat islands, and creating recreation opportunities. However, maintaining wetlands in urban areas faces many challenges, such as the reduction of hydrological functions, changed water regimes due to barriers, contamination by wastewater, habitat loss due to land-use change, and loss of biodiversity due to the entry of alien species. In this article, we review the theoretical background of wetlands in urban areas through the existing studies in the literature. We provide knowledge on urban wetlands and highlight the benefits of these wetlands in urban areas. These benefits include sustainability, biodiversity, urban heat islands, social perception, and recreation values. We also summarize the objectives, methodologies, and findings of the reviewed articles in five tables. In addition, we summarize the critical research gaps addressed in the reviewed articles. Our review study addresses the research gaps by performing a rigorous analysis to identify significant open research challenges, showing the path toward future research in the field. We further discuss and highlight the role of policymakers and stakeholders in preserving wetlands and finally present our conclusions

Urban Wetlands: A Review on Ecological and Cultural Values

Wetlands are a critical part of natural environments that offer a wide range of ecosystem services. In urban areas, wetlands contribute to the livability of cities through improving the water quality, carbon sequestration, providing habitats for wildlife species, reducing the effects of urban heat islands, and creating recreation opportunities. However, maintaining wetlands in urban areas faces many challenges, such as the reduction of hydrological functions, changed water regimes due to barriers, contamination by wastewater, habitat loss due to land-use change, and loss of biodiversity due to the entry of alien species. In this article, we review the theoretical background of wetlands in urban areas through the existing studies in the literature. We provide knowledge on urban wetlands and highlight the benefits of these wetlands in urban areas. These benefits include sustainability, biodiversity, urban heat islands, social perception, and recreation values. We also summarize the objectives, methodologies, and findings of the reviewed articles in five tables. In addition, we summarize the critical research gaps addressed in the reviewed articles. Our review study addresses the research gaps by performing a rigorous analysis to identify significant open research challenges, showing the path toward future research in the field. We further discuss and highlight the role of policymakers and stakeholders in preserving wetlands and finally present our conclusions

Comparative analysis of phycoerythrin production in cryptophytes

Phycobiliproteins are pigments with uses in pharmacology, cosmetics, foods, and as fluorescent probes in biochemistry. Cryptophyte microalgae are one possible source of phycobiliproteins as well as other molecules such as omega-3 fatty acids. The use of cryptophytes in biotechnology is currently very limited and especially the potential of freshwater species is poorly documented. For commercial microalgae production, it is important to find the best performing strains in terms of growth and yields of the products of interest. Phycoerythrin is a phycobiliprotein with red colour and strong yellow fluorescence. In this study, we evaluate the growth and phycoerythrin production of eight strains of freshwater cryptophytes belonging to the genus Cryptomonas, comparing them to two marine strains. The strains are grown in batch cultures under standardised conditions. Most of the studied freshwater strains have lower growth rates and all of them have lower biomass yields than the marine strains. However, most of them have much higher cellular phycoerythrin concentrations, which in the case of two strains leads them to a significantly higher overall phycoerythrin yield. There is large variation among cryptophytes in growth rates and phycoerythrin content. Our results suggest that freshwater cryptophytes of the genus Cryptomonas may be better sources of phycoerythrin than the more extensively studied marine strains.Peer reviewe

Urban water bodies and recreational opportunities in Finland

Urban water bodies provide recreational opportunities to residents such as swimming, boating, fishing and spending leisure time. The recreational opportunities offered by water bodies contributes to both physical and mental health. In Finland, there are almost unlimited possibilities to enjoy water bodies in urban areas by having 3.4 million hectares of inland water resources, e.g., lakes, ponds, and coastal wetland and 5.2 million hectares of marine waters. In this paper, we highlight the recreational values offered by these water areas in the urban context. We use water-based outdoor recreation statistics collected from the three provinces in Finland called Uusimaa, Pirkanmaa, and Pohjanmaa. As a result, we show that the demographic structure, access to the water areas are linked to the type of recreation activities such as swimming, fishing and boating. Thus, resulting in the well-being of people living in cities.Peer reviewe

Changes in phytoplankton in a boreal lake during a 14-year period

Peer reviewe

Culturing of Selenastrum on diluted composting fluids; conversion of waste to valuable algal biomass in presence of bacteria

Growth and fatty acid production of microalga Selenastrum sp. with associated bacteria was studied in lab-scale experiments in three composting leachate liquids. Nutrient reduction in cultures was measured at different initial substrate strengths. A small, pilot-scale photobioreactor (PBR) was used to verify labscale results. Similar growth conditions supported growth of both Selenastrum and bacteria. CO2 feed enhanced the production of biomass and lipids in PBR (2.4 g L-1 and 17% DW) compared to lab-scale (0.1-1.6 g L-1 and 4.0-6.5% DW) experiments. Also prolonged cultivation time increased lipid content in PBR. At both scales, NH4-N with an initial concentration of ca. 40 mg L-1 was completely removed from the biowaste leachate. In lab-scale, maximal COD reduction was over 2000 mg L-1, indicating mixotrophic growth of Selenastrum. Co-cultures are efficient in composting leachate liquid treatment, and conversion of waste to biomass is a promising approach to improve the bioeconomy of composting plants. (C) 2017 The Authors. Published by Elsevier Ltd.Peer reviewe

Prediction of drug dissolution from Toremifene 80 mg tablets by NIR spectroscopy

The aim of our study was to justify substitution of dissolution analysis for NIR measurement of Toremifene 80 mg tablets. We studied implementation of a NIRS method by integrating the method development to discrimination power of the dissolution method. Hence, we analyzed 20 DoE tablet batches and studied which of the critical formulation factors affecting dissolution were statistically significant. To study if these factors can be detected by NIRS, PLS calibration models were developed. Finally, PLS model was built to correlate NIR data with the actual dissolution results to predict the released amount of toremifene in 30 min. To obtain the data the tablet batches were measured by NIR using diffuse reflectance technique and multivariate analysis tool was used to calibrate the NIRS models. Correlations between the critical formulation factors and the NIR spectra of Toremifene 80 mg tablet were shown and it was thus justified to develop a NIRS prediction model for dissolution. Variance (R-2), standard error of estimate (SEE) and standard error of prediction (SEP) of the model were 90.0%, 4.3% and 5.9%, respectively. It was thus shown that mull-phased and time consuming dissolution procedure could be substituted for fast non-invasive NIRS method.Peer reviewe