The amount of various phosphorus (P) fractions in the sediment and the relationship between the amount of P and sediment particle size were investigated in a constructed wetland southwest of Linköping. Furthermore, the possible correlation between clay content in the sediment and distance from the inlet was investigated. Sediment samples were collected along three transects from the inlet to the outlet, with six samples in each transect. In order to measure the soluble P, an NH4Cl extraction was done. This was also analysed for total soluble P after oxidation with peroxodisulphate. The sediment was also analysed for total-P and organic P by drying, dispersion in a mortar and sieving followed by boiling in HCl. Analysis of phosphate-P in all extracts was done with an acid molybdate solution and ascorbic acid, forming a blue complex that was measured spectrophotometrically. There was no significant relationship between soluble P or soluble total-P and the proportion of clay in the sediment samples. This was also the case for total-P and organic-P. Generally, the levels of phosphorus in the sediment were low, which may result from too deep sediment samples, causing the settled P-rich sediment to be diluted by the terrestrial soil underneath the wetland. There was a low proportion of clay in the sediment (4 – 18 %), which made it difficult to detect any correlation with soluble-P content. When omitting the samples at the inlet (which were more influenced by vegetation than the others), a significant positive correlation between percentage of clay and distance from the inlet was detected, suggesting that clay particles were settling in the wetland.

Eutrophication is a current problem on coastal lines worldwide. Cirripedia like the northern acorn barnacle Semibalanus balanoides actively help to prevent high amounts of plankton in the coastal zones by filtering plankton out of the surrounding water. This investigation focuses on the movements of Semibalanus balanoides in comparison to increasing concentrations of plankton in the water (between 33mg and 110 mg particles per litre) which simulate eutrophication. The four factors feeding activity, pumping activity, isolation time and clogging of the feeding apparatus in relation to the plankton concentration of the water were examined. The results show significant interaction between pumping movement and the plankton concentration. The feeding activity, the isolation time and the clogging compared to the plankton concentration get no statistical results. Less feeding activity and an increase in pumping behaviour will not decrease the amount of plankton in the coastal waters which will increase the problems of eutrophication. The paper shows that more investigation on suspension feeders and their surroundings needs to be done to be able to understand the dangers fully.

Phosphorus (P) is a limiting nutrient regulating productivity in both freshwater and marine ecosystems. A full knowledge of the sources and pathways of the P cycle is essential for understanding aquatic ecosystem function and for managing eutrophication. However, two significant pathways are poorly understood or remain uncharacterized. First, aquatic metazoans represent a significant internal regenerative pathway of P through the mineralization, translocation (i.e., benthic pelagic coupling) and excretion of nutrients. Rates of P excreted are expected to vary across taxa (i.e., zooplankton vs. mussels vs. benthic macroinvertebrates vs. fish), yet the significance of any one group of taxa in supplying P to bacteria and algae is unknown. Therefore, I developed the first comprehensive set of empirical models of nutrient release for aquatic metazoans (zooplankton, mussels, other benthic macroinvertebrates, and detritivorous and non-detritivorous fish) and compared inter-taxonomic differences in P excretion. I demonstrated that detritivorous fish excrete P at rates greater than all other taxa (as a function of individual organism mass); whereas, mussels generally excreted P at rates less than other taxa. Significant differences in the rate of P excretion between zooplankton and non-detritivorous fish were not observed [i.e., the allometry of P excretion was similar between zooplankton and non-detritivorous fish (as a function of individual body mass)]. I subsequently applied the models to assemblage biomass and abundance data to examine and compare the relative contribution of each taxa to the internal supply of P, and to examine the turnover time of P bound in metazoan biomass. I clearly demonstrated a hierarchy in the contribution by different metazoan assemblages to P cycling (zooplankton > benthic macroinvertebrates > mussels > fish) and clarified the significance of different metazoan taxa in P cycling. Moreover, I demonstrated that the slow turnover time of P bound in fish biomass (relative to other metazoans) indicates that fish are important as sinks rather than sources of P. A second potentially significant P pathway is through the influence of ultraviolet radiation (UVR) on P cycling. UVR may alter P cycling abiotically through changes in P availability and biotically through changes in the acquisition and regeneration of dissolved P by plankton. However, the significance of P released from the photodecomposition of dissolved organic P compounds (DOP), and the effect of UVR on the uptake and regeneration of dissolved P, the turnover of particulate P, and on ambient phosphate (PO43-) concentration has not been investigated and remains unknown. Therefore, my initial experiments applied the novel use of radiophosphate uptake assays to quantify the significance of the photodecomposition of DOP to PO43-. I concluded that the liberation of PO43- through the photodecomposition of DOP is not a significant pathway. However, the photochemical liberation of PO43- from suspended sediments was evident and should be an important pathway supplying PO43- to plankton in shallow polymictic lakes. This represents the first study to identify this P pathway in lakes. The turnover time of the PO43- pool increased under UVR irradiance (i.e., uptake of P by plankton decreased), while the regeneration rate of dissolved P and turnover rate of planktonic P were generally not affected. The net effect of UVR was an increase in steady state PO43- concentration (ssPO43-). Alkaline phosphatase activity (APA) in the dissolved and particulate fractions was significantly reduced in UVR treatments, but unrelated to changes in P uptake as proposed in the literature. This is the first study to comprehensively investigate the biotic effects of UVR on P cycling and represents a major advancement in the field of photobiology. In summary, I have characterized several poorly understood pathways in the P cycle of lakes. With the models I have developed, aquatic metazoans can now be integrated into the P cycle of lakes, for example, with other internal and external sources of P (e.g., from inlets, lake sediments and the atmosphere). This will advance our knowledge of P cycling, and will provide researchers with a better understanding of the nutrient pathways supporting primary production.

Accurate estimates of the amount of groundwater entering a lake on a yearly basis may provide valuable information for assessing contaminant loadings such as nutrient mass fluxes and the subsequent contribution of groundwater to eutrophication. Groundwater exchange with lakes is often a critical component of a lake’s water balance, yet its quantification has often proven problematic. Large component uncertainties preclude accurate estimation of the groundwater flux, upon which the assessment of contaminant loadings may depend. In this study, water balance techniques for lake systems were assessed at Lake Pyhäjärvi (near Säkylä, SW Finland), a relatively large lake in a long established agricultural area. A water balance was conducted over 38 water years to estimate the net groundwater discharge into the lake. This was compared with groundwater flux estimates via Darcy’s Law for the adjacent Honkala Aquifer in the Kuivalahti-Säkylä tributary esker (a potential conduit for groundwater impacted by agricultural practices). Direct runoff estimates were initially made using an average of river flow per unit area ratios from the two rivers that flow into the lake. Adjustments to these estimates were made using PART (Rutledge, 2007) hydrograph separation results from the larger river. The mean net groundwater discharge increased from -73 to +38mm per unit lake area (-4.8 to +2.5% of average total inflow) due to these adjustments, which yielded a better qualitative match with observations at the lake (e.g., Rautio, 2009; Rautio and Korkka-Niemi, 2011). Uncertainty analysis for the water balance indicated that relative uncertainty ranged from 40 to 2900% on the net groundwater flux, while the average absolute uncertainty was 118mm per unit lake area. Groundwater discharge estimates based on Darcy’s Law were ≤ 22 mm per unit lake area (≤1.4% of average total inflow) with sizeable uncertainty (± one order of magnitude). Most of the uncertainty on the net groundwater discharge estimates was incurred from the evaporation, precipitation, and direct runoff components; esker flux uncertainty was essentially due to error on the hydraulic conductivity estimate. The resolution of the water balance method suggests that it is better suited to lakes with relatively large net groundwater contributions (>5% of average total inflow). Results highlight the following needs for large lake water balances: improvements in the accuracy of evaporation, precipitation, and direct runoff component estimates; and uncertainty analysis. Groundwater contributions to inflow rivers may be more important than direct discharge from highly permeable subsurface materials adjacent to lakes in the context of understanding nutrient loadings to large lakes.

Phosphorus (P) is a limiting nutrient regulating productivity in both freshwater and marine ecosystems. A full knowledge of the sources and pathways of the P cycle is essential for understanding aquatic ecosystem function and for managing eutrophication. However, two significant pathways are poorly understood or remain uncharacterized. First, aquatic metazoans represent a significant internal regenerative pathway of P through the mineralization, translocation (i.e., benthic pelagic coupling) and excretion of nutrients. Rates of P excreted are expected to vary across taxa (i.e., zooplankton vs. mussels vs. benthic macroinvertebrates vs. fish), yet the significance of any one group of taxa in supplying P to bacteria and algae is unknown. Therefore, I developed the first comprehensive set of empirical models of nutrient release for aquatic metazoans (zooplankton, mussels, other benthic macroinvertebrates, and detritivorous and non-detritivorous fish) and compared inter-taxonomic differences in P excretion. I demonstrated that detritivorous fish excrete P at rates greater than all other taxa (as a function of individual organism mass); whereas, mussels generally excreted P at rates less than other taxa. Significant differences in the rate of P excretion between zooplankton and non-detritivorous fish were not observed [i.e., the allometry of P excretion was similar between zooplankton and non-detritivorous fish (as a function of individual body mass)]. I subsequently applied the models to assemblage biomass and abundance data to examine and compare the relative contribution of each taxa to the internal supply of P, and to examine the turnover time of P bound in metazoan biomass. I clearly demonstrated a hierarchy in the contribution by different metazoan assemblages to P cycling (zooplankton > benthic macroinvertebrates > mussels > fish) and clarified the significance of different metazoan taxa in P cycling. Moreover, I demonstrated that the slow turnover time of P bound in fish biomass (relative to other metazoans) indicates that fish are important as sinks rather than sources of P. A second potentially significant P pathway is through the influence of ultraviolet radiation (UVR) on P cycling. UVR may alter P cycling abiotically through changes in P availability and biotically through changes in the acquisition and regeneration of dissolved P by plankton. However, the significance of P released from the photodecomposition of dissolved organic P compounds (DOP), and the effect of UVR on the uptake and regeneration of dissolved P, the turnover of particulate P, and on ambient phosphate (PO43-) concentration has not been investigated and remains unknown. Therefore, my initial experiments applied the novel use of radiophosphate uptake assays to quantify the significance of the photodecomposition of DOP to PO43-. I concluded that the liberation of PO43- through the photodecomposition of DOP is not a significant pathway. However, the photochemical liberation of PO43- from suspended sediments was evident and should be an important pathway supplying PO43- to plankton in shallow polymictic lakes. This represents the first study to identify this P pathway in lakes. The turnover time of the PO43- pool increased under UVR irradiance (i.e., uptake of P by plankton decreased), while the regeneration rate of dissolved P and turnover rate of planktonic P were generally not affected. The net effect of UVR was an increase in steady state PO43- concentration (ssPO43-). Alkaline phosphatase activity (APA) in the dissolved and particulate fractions was significantly reduced in UVR treatments, but unrelated to changes in P uptake as proposed in the literature. This is the first study to comprehensively investigate the biotic effects of UVR on P cycling and represents a major advancement in the field of photobiology. In summary, I have characterized several poorly understood pathways in the P cycle of lakes. With the models I have developed, aquatic metazoans can now be integrated into the P cycle of lakes, for example, with other internal and external sources of P (e.g., from inlets, lake sediments and the atmosphere). This will advance our knowledge of P cycling, and will provide researchers with a better understanding of the nutrient pathways supporting primary production.

Human-induced eutrophication is indirectly affecting aquatic organisms by altering their environment. This brings on altered selective pressures and could thereby cause changes in the genetic composition of exposed populations. Since anthropogenic environmental changes are usually occurring at a much higher rate than naturally occurring changes, they force populations to adapt to the new conditions faster than normal. Here, I have studied populations of three-spined sticklebacks (Gasterosteus aculeatus) from four eutrophicated and four adjacent reference sites, along the coast of Finland, to investigate if this species has responded genetically to the human-induced eutrophication of the Baltic Sea. For this purpose I used amplified fragment length polymorphism (AFLP) and found distinctions in genetic composition between the two habitats, as well as similarities between populations from eutrophicated sites. This suggests a similar genetic response to eutrophicated conditions by stickleback populations from different geographical areas. Moreover I found a distinct geographic structure among three-spined sticklebacks in the Baltic Sea.

Human-induced eutrophication is indirectly affecting aquatic organisms by altering their environment. This brings on altered selective pressures and could thereby cause changes in the genetic composition of exposed populations. Since anthropogenic environmental changes are usually occurring at a much higher rate than naturally occurring changes, they force populations to adapt to the new conditions faster than normal. Here, I have studied populations of three-spined sticklebacks (Gasterosteus aculeatus) from four eutrophicated and four adjacent reference sites, along the coast of Finland, to investigate if this species has responded genetically to the human-induced eutrophication of the Baltic Sea. For this purpose I used amplified fragment length polymorphism (AFLP) and found distinctions in genetic composition between the two habitats, as well as similarities between populations from eutrophicated sites. This suggests a similar genetic response to eutrophicated conditions by stickleback populations from different geographical areas. Moreover I found a distinct geographic structure among three-spined sticklebacks in the Baltic Sea.

Jung Jeng Lake located in Mei Nong in south of Taiwan, is the origin of Mei Nong Hakka culture. Owing to stockbreeding hogs, cultivation and domestic wastewater in the upstream of Jiang Tz Liau River that finally flows into Jung Jeng Lake for years, the lake thus suffered extremely serious problem of eutrophication. In addition, the water hyacinth remain seeds in the lake and reproduce resulting in speeding up the lacustrine silt that would greatly shorten the life of Jung Jeng Lake. Using artificial lagoon and artificial floating island were found able to improve the water quality of lake. Therefore, we could sightseeing resource, historic site, and ecological resources of Mei Nong. This research applied the advantages of ecological engineering methods to restore the Jung Jeng Lake, and thus the southern Taiwan unique Hakka tourism can be presented.

A 3D numerical model ¡V COHERENS has been applied to construct a coupled hydrodynamic and ecological model for studying Tapeng Bay, which is a coastal lagoon situated in southwest of Taiwan. The simulations have been carried out to study the influences and their interacting mechanisms among the tidal currents, nutrients and micro planktons in the Lagoon. Model results have been compiled for calculating the nutrient fluxes and the primary productions in the Tapeng Bay. Tapeng Bay is a semi-enclosed coastal lagoon, which has only one tidal inlet for exchanging lagoon water with the coastal currents along the Kaoping coast on the narrow shelf in southwest of Taiwan. The study area is situated in the tropical climate zone where has sunshine through out the year except the rainy days concentrated in the summer season, which is influenced by the southwest monsoon. There are several drainage channels that collect the untreated domestic sewerage and wastewater discharged from the fish farms surround the lagoon. The discharges in these channels are usually low during the dry season. The solid contained in the water are mostly settled on the channel beds. During the raining season, high discharges due to the storm rainfalls re-suspend the sediments and carry into the lagoon. These sediments, which contain high concentrations of suspended solids and nutrients, cause the Bay water highly eutrophied. Therefore, the Bay is fully influenced by the seasonal variations. There are a lot of aquaculture, i.e. oyster farming and fish cage, in the Bay area since the water is calm and rich. But the balance between the nature and the anthropogenic disturbance is breaking. Besides the water level variation generated from the tidal inlet, the fresh water inflow from 3 major channels are included in the model to simulate their influences to the hydrodynamics and the density driven circulation due to changing salinities and temperatures from these inlets. Plankton, detritus, dissolved nutrients and dissolved oxygen is taking into account as the model variables for this marine eco-system. The plankton growth is mainly generated due to temperature, light intensity and nutrient level. Only the nitrogen cycle has been considered in the model by assuming there are enough supply of phosphate and silicate. Model runs have been carried out according to different seasonal situations of the boundary conditions. Furthermore, climates (heats, lights, winds, etc) are also included in the model to distinct seasonal characteristics. It is shown, from the model results, that the currents mainly dominate the distribution of nutrients in the Tapeng Bay. The nutrient level controls plankton growth. The nutrient sources are mainly coming from the coastal currents (through tidal inlet) in the wintertime, whereas the summer source was from the drainage channels due to the wash out by the high discharge rates. Beside these, dissolved oxygen concentrations in the Bay water are strongly influenced by the plankton growth rate, faster the photosynthesis higher the DO concentrations. The eutrophication levels of the Tapeng Bay water have been compiled using the plankton carbon level modeled at various situations. According to the Nixon standard (1995), Tapeng Bay has eutrophication through out the year. Mesotrophic condition can be observed during the wintertime, whereas the hypereutrophic level can be concluded during the raining season.

Phosphorus (P) is a pollutant in freshwater systems because it promotes eutrophication. The dairies in the North Bosque and its water body segments import more P than they export. Dairies accumulate P-rich effluent in lagoons and use the wastewater for irrigation. As more P is applied as irrigation than is removed by crops, P accumulates in the soil. During intense rainfall events, P enters the river with stormwater runoff and can become bio-available. Reducing the P applied to the land would limit P build up in the soil and reduce the potential for P pollution. Since wastewater P is associated with suspended solids (SS), the flocculants, poly-DADMAC and PAM, were used to reduce SS. To precipitate soluble P from the effluent, NH4OH was added to raise the pH. Raw effluent was collected from a dairy in Comanche County, TX, and stored in 190-L barrels in a laboratory at Texas A&M University. Flocculant additions reduced effluent P content by as much as 66%. Addition of NH4OH to the flocculated effluent raised the pH from near 8 to near 9, inducing P precipitation, further reducing the P content. The total P reduction for the best combination of treatments was 97%, a decrease from 76 to 2 mg L-1. If this level of reduction were achieved in dairy operations, P pollution from effluent application would gradually disappear.