No description available.

Salford Quays were created from the highly polluted Manchester docks after their closure in 1984. In order to make use of the potential for an attractive waterside location in the centre of Greater Manchester, it was decided to redevelop the area for commercial, recreational and residential use. This involved isolating and artificially mixing the docks and instigating a series of management interventions, including the introduction of fish, macrophytes and the invasive filter-feeding bivalve Dreissena polymorpha. The positive results of these interventions are clearly visible in modern day Salford Quays (SQ) which now provides a home to several thousand people, office and retail space, a site for water sports activities and the location of the new BBC Media City. Despite this success the precise drivers of environmental improvements and the extent to which each intervention has contributed to restoration has proven elusive. Therefore further investigation is warranted, not only to inform future water quality management but also to determine the ecosystem processes involved and to increase our understanding of how lentic ecosystems function. Restoration of SQ has been accompanied by intensive monitoring of water quality and ecology from 1984 to the present day. The resulting dataset has been analysed to examine the relationships between the physiochemical environment, management and phytoplankton community structure using a combination of non-linear regression and ordination techniques. This has explained the patterns behind the change from Planktothrix agardhii dominated eutrophy to the clear waters of the present day and indicated the importance of nutrient control and D. polymorpha filtration on past and present ecosystem function. This study has demonstrated how useful non-linear approaches are to the study of ecology and a strong case has been made for their incorporation into future analysis. To quantify the effects of the introduced D. polymorpha population, further data were collected on their spread and effects on the SQs ecosystem. Using the limited past data available, plus a full scuba dive survey in 2010 and ex situ lab experiments on filtration rate it has been possible to quantify their effect on the phytoplankton communities and show that mussels are likely a significant controlling factor in all basins except the larger, Huron basin where populations remain inexplicably low. In parallel a new molecular method has been developed to chart the spread of D. polymorpha both around SQ and in new areas via a 9 loci microsatellite multiplex to assess both historic effects and the potential for future dispersal. Finally, a high resolution, multi-parameter dataset was collected over 2010/2011 to determine the current seasonal patterns in biological and physiochemical environment in SQ. It has shown the overwhelming influence of D. polymorpha to the annual and inter-annual variation in water quality and plankton ecology and, when combined with molecular analysis, shows the possible implications of their use in water management. This thesis will serve to broaden our understanding of freshwater ecology and will prove especially useful in future management projects, especially in relation to other artificial waterways and lake systems.

No description available.

No description available.

Studies have been carried out on the phytoplankton of two freshwater lakes-eutrophic Rostherne Mere (Cheshire, UK) and mesotrophic Lake Glubokoe (Moscow region, Russia). Diversity was investigated in relation to two major aspects : (a) species composition, with indices of diversity being estimated from phytoplankton cell and colony counts, and (b) intraspecific diversity, looking at variation in elemental composition within selected species. The major genera of phytoplankton in Rostherne Mere included Stephanodiscus and Asterionella (spring diatom bloom), Chlamydomonas and Sphaerocystis (clear water phase), and a species assembly dominated by Microcystis (1997) or Ceratium (1999) in the late summer/autumn bloom. The sequence of major algal groups recorded at Lake Glubokoe were: chrysophytes, dinoflagellates and diatoms in spring, chlorophytes and blue-greens in the clear water phase, and an assembly of diatoms, blue-greens, dinoflagellates and chrysophytes in the late summer/autumn bloom. Indices of species diversity were determined in relation to species richness (Richness index, species count), general diversity (Shannon index) and species dominance (Simpson index). In both lakes, species richness and general diversity were greatest in the late summer bloom, a period of maximum phytoplankton stability and high productivity, characterised by K-selected species. Species dominance in Rostherne Mere was highest at extremes of productivity, including times of low algal biomass (clear water phase, 1997 and 1999) and very high biomass (late summer bloom, 1999). In Lake Glubokoe species dominance was maximal at the end of the summer/autumn bloom, a period of intermediate productivity and dominance of a limited number of species. Overall diversity (maximum seasonal Shannon index) decreased with increase in productivity, being highest in Lake Glubokoe (1998, low productivity), intermediate in Rostherne Mere 1997, and lowest in Rostherne Mere 1999 (highest chlorophyll-a levels). Phytoplankton diversity within the water column (mid-day) was determined at the key phases in lake stratification in Rostherne Mere (1999) and at the period of late summer bloom in Lake Glubokoe (1998). At each phase of the seasonal growth cycle, differences in the vertical distribution of individual species and algal groups reflected positioning of algae in relation to ambient conditions (nutrients, light, temperature, density gradients) or sedimentation within the water column. Phytoplankton diversity in species richness closely corresponded to the overall phytoplankton population (biomass profile and individual counts), usually having the maximum values in the epilimnion. Profiles of species dominance varied markedly in some of the depth analyses. High species dominance reflected either the growth of individual species (surface populations of chlorophytes in the clear water phase -Rostherne Mere) or the accumulation of populations at a particular depth due to sedimentation (hypolirrmion peak of diatoms in Lake Glubokoe). Phytoplankton statistical groups and assemblages were analysed within the water column of Rostherne Mere at the time of markedly high algal productivity (late summer bloom in 1999). Intraspecific diversity was examined on the basis of elemental composition of three main species (Ceratium hirundinella, Anabaena flos-aquae and Microcystis aeruginosa), sampled within the same water column in Rostherne Mere. The elemental composition of single cells within a mixed phytoplankton preparation was determined using Electron Probe X-ray Microanalysis. Intraspecific variation was investigated in relation to differences in elemental composition within the water column, variation within micropopulations, and pattern of elemental correlation. X-ray analysis detected a similar range of elements in the populations of Ceratium, Anabaena and Microcystis: magnesium, silicon, phosphorus, sulphur, chlorine, potassium, calcium, with P as the major anionic element, K as the major cation. Si was present at substantial levels. Elemental composition varied considerably within micropopulations of each species. Variation in the concentration of most elements was unimodal. Bimodal distribution was shown by K in Ceratium cells, and by Si in Anabaena and Microcystis cells, indicating particular subpopulations, within these species. Distinct subpopulations of high-Si and low-Si cells in Anabaena and Microcystis were attributed to the presence of Si as a surface layer associated with Al in high-Si cells. Low-K cells in Ceratium were seen as part of the population undergoing senescence. The pattern of elemental correlations revealed a major statistical association between Mg, P, S and K in each species throughout the water column. The XRMA results suggested an underlying homogeneity in the elemental composition of Ceratium, Anabaena and Microcystis within the top 8 m of the water column.

The ecology of ponds is threatened by urbanisation and as cities expand pond habitats are disappearing at an alarming rate. Pond communities are structured by local (water quality, physical) and regional (land-use, connectivity) processes. Since ca1904 >80% of ponds in Birmingham, U.K., have been lost due to land-use intensification, resulting in an increasingly diffuse network. A survey of thirty urban ponds revealed high spatial and temporal variability in water quality, which frequently failed environmental standards. Most were eutrophic, although macrophyte-rich, well connected ponds supported macroinvertebrate assemblages of high conservation value. Statistically, local physical variables (e.g. shading) explained more variation, both in water quality and macroinvertebrate community composition than regional factors. Nonetheless, habitat availability within the wider landscape was important. Ecosystem functioning (leaf-litter breakdown) along a rural-urban gradient was confounded by habitat area, despite a decrease in functional redundancy. Ponds are identified that promote network connectivity and management of land-use within 100m may buffer against diffuse pollution with reductions in riparian shading required to improve growth conditions for oxygenating vegetation and to reduce nutrient levels. The results indicate that many urban ponds are threatened habitats that require active management to protect and restore water quality, biodiversity and ecosystem functioning.

The use of artificial ponds for the temporary storage of urban stormwater runoff is a commonly used environmental engineering practice in North America. By releasing runoff at a rate slower than the initial generation rate, on-line flood control is achieved. Urban runoff typically has a high eutrophication potential, so that single unit detention ponds may sustain excess algal/macrophyte growth within only a few years of construction. A research project was undertaken between 1992 and 1995 on stormwater detention ponds in the Province of Saskatchewan, Canada. Three ponds aged 15 to 17 years old are described in this thesis. The focus of the study was to describe the nutrient characteristics and associated phytoplankton cycles within these systems, and to further identify potential management options for water quality improvement. Four to five months of permanent winter ice cover occurs in the central zone of the Province. Of the three systems reported here, complete winter anoxia is typical in two (1.7 to 1.8 m deep - mixed), while partial or complete anoxia occurs in the third pond according to the timing of snowmelt (2.7 m deepthermally stratified in summer). Therefore, biological community structure is limited by the overwintering potential. Accumulated nitrogen, phosphorus, and silica sustained green algae and diatom blooms following ice-melt, and pH values of >9.5 often occurred by late April. During the open water season, hypereutrophic conditions were sustained and the systems typically oscillated between blue-green and green algal dominance according to flushing, external N- loading and mixing. Dissolved inorganic nitrogen:phosphorus (DIN:DIP) ratios of stormwater were typically below Redfield stoichiometry. Therefore, inpond DIN:DIP ratios of <3 were typical, with one system frequently <1. These low ratios were the result of both internal P-Ioading and N loss mechanisms during dry weather storage periods, and DIP >0.25 mg/L sometimes occurred within the euphotic zone. Dense N-fixing Anabaena sp. blooms periodically developed under suitable climatic conditions. Nitrogen fixed into the system in turn supported non-fixing species as a subsiding bloom was mineralized. Nutrient and phytoplankton cycles fluctuated within short time scales, according to physical disturbances and algal self-shading at peak biomass (sometimes > 100 mm3/L). Average algal biomass levels in the stratifying pond were lower than the other ponds on account of sedimentary losses to an anaerobic bottom zone. xv Grazing by herbivorous zooplankton was generally not significant in promoting phytoplankton species successions. The zooplankton of all three systems were dominated by cyclopoid copepods and rotifers. Predation by fish (minnows), food quality (blue-green algae dominance), and losses during large flushing events are among factors which may suppress desirable large-bodied cladoceran zooplankton in these systems. The mean surficial (1 cm) sediment iron content was lowest (",,27 mg Fe/g dry wt VS. 38 mg Fe/g dry wt) and the organic content was highest ("" 18% LOI VS. 11 % LOI) in the stratifying pond compared to the two non-stratifying ponds. Also, the mean sediment depth in the stratifying pond (not including the littoral slope sediments) was highest (",,21 cm VS. 9 to 13 cm), when compared to the two non-stratifying ponds. Iron may be lost from the stratifying pond by flushing of anaerobic hypolimnetic waters during stormflows. Groundwater inflows to the stratified pond resulted in a higher alkalinity system and consequently the highest mean sediment calcium content of the three ponds (",,82 mg Calg dry wt, VS. 31 to 34 mg Calg dry wt). The surficial sediment total-P [TP] of the three ponds ranged from 0.97 to 1.26 mg/g dry wt, and in all cases 11 to 15% of this was associated with inorganic extractable P, with more in the calcium than the iron/aluminium bound fraction. At peak water temperatures (s:26°C) internal P loading rates >30 mg/m2/day were calculated from field data in the non-stratifying ponds. An average P release rate of 15 mg/m2/day was measured during anaerobic incubation of sediment cores from one of these ponds at 20°C. However, aerobic incubation of these sediments showed that Fe concentrations were sufficient to provide high P uptake potential when oxidized. Anaerobic incubations of intact cores from the stratifying pond gave average release rates of 5 to 16 mg/m2/day from 5 to 20°C. Field data also showed that net internal P loads were reflected by changes in the surficial sediment P pool. A nutrient input budget for the stratifying pond showed that groundwater baseflow supplied a massive amount of DIN (as N03) relative to stormflows. If the seasonal stormwater DIP load was expressed as an averaged areal mass/day, the average seasonal internal P loading (-8 to 10 mg/m2/day) was four times higher. Theoretical P removal efficiencies of 63 to 80% were calculated for the ponds, but resuspension and flushing of internally loaded P accumulated during dry weather may reduce these values. A TP mass export of 0.25 to 0.3 kg/ha impervious/0.58 year from 250 mm precipitation was calculated from runoff studies in Saskatoon. In experimental work, inorganic nitrogen additions to the most N-limited pond were carried out from May to July 1994. Complete dominance of the spring to mid-summer phytoplankton by green algae and diatoms was maintained. However, warming water increased P recycling, and during a period of lower than average wind speeds a non-fixing blue-green algae bloom developed in place of the usual N-fixing algae bloom. No significant alteration to the zooplankton species composition was evident despite structural changes to the vernal phytoplankton composition. Phosphorus inactivation with aluminium sulphate was successful in improving water quality for a six week period during which the control pond developed a dense N-fixing algae bloom. Sediment surface oxidation was promoted by the reduction of productivity, and P adsorption to sediment iron complexes was an important secondary benefit. Several very large storms were ultimately responsible for exchanging approximately 100% of the storage volume, after which bloom conditions were restored. The procedure may be an effective short-term measure, but benefits will not extend beyond major exchange events. Management options for aesthetic improvement are very limited in these hypereutrophic ponds. External DIP loads will continue to be at least 5 to 10 times greater than threshold values for nuisance algal growth, and seasonal internal loading of P is high. The inability of increased N availability to prevent blue-green algae bloom formation, together with high exchange volumes and a general lack of herbivorous zooplankton, suggest that top-down management interventions (limited by overwintering) to control zooplanktivores are unlikely to prevent algae bloom formation in ponds with lower volume:catchment area ratios. More work is required with regard to nutrient budgets if pond operational efficiencies are to be accurately assessed. In addition, measurement of primary productivity would provide invaluable information for any attempt to model algal growth in these ponds. Sediment removal is ultimately required as a long-term maintenance measure, but more information on the incorporation of P inactivation agents directly into the sediment structure is needed as a means to retard internal P loading.

Short term and irregular sampling in Loch Creran over recent decades suggested that changes may be occurring in the phytoplankton community in the loch. This study sought to confirm this suggestion. After instigating a regular sampling regime during 2008 and 2009 it became clear that significant changes had occurred, relative to information from the 1970s, in both the numbers of phytoplankton in the loch and in their biomass, particularly during the time of the spring bloom. Utilising a tool to assess change in the phytoplankton community, it also became clear that significant changes had occurred in the composition of the phytoplankton in Loch Creran. Work was undertaken to explore possible explanations behind these changes. The e�ect that toxic, anti-fouling compounds, arising from an increase in leisure boating in Loch Creran, were having on the productivity of phytoplankton in the loch was considered by adapting an existing assimilative capacity model for phytoplankton growth. It was found, that at present levels of boating activity, the concentration of anti-fouling products present in the loch, would not be great enough to significantly impact on phytoplankton growth. Nutrient samples collected during 2009 showed no significant changes in the concentration of silicate or nitrate in the loch, but phosphate levels were found to be significantly lower. A review of the e�ects of grazing on phytoplankton by farmed mussels in Loch Creran indicated that, at current levels, this would not account for the decrease in phytoplankton numbers observed in the loch. Significant changes were observed in the water temperature in the loch and in the intensity and pattern of local rainfall. Increased levels of rainfall in the first three months of the year were found to be high enough to influence the rate of flushing and the rate of phytoplankton washout from the loch. A correlation was found between the availability of light in the surface layers of the loch and the concentration of phytoplankton present in these layers. This correlation was found to exist, throughout the year and not only, as previously thought, during the winter months. In conclusion, the observed decline in phytoplankton numbers in Loch Creran, was attributed to changes in local weather patterns, that had an impact on the physical structure of the water column, washout rates, the pattern and intensity of heterotrophic grazing and the availability of light.

Release of phosphorus (P) from bed sediments to overlying waters (internal P-loading) can detrimentally alter ecological structure and function in shallow lakes. The theory of regime shifts states that shallow lakes can exist in alternative states and that shifts between states can occur as a result of disturbance. The main hypothesis of this study was that the use of a P-capping agent (Phoslock®) in shallow lakes (i.e. a controlled disturbance) will break down the internal P-loading feedback mechanism resulting in a regime shift. Experiments, ranging in scale from mesocosm to whole-lake, showed that Phoslock® significantly reduced internal P-loading by increasing the mass of P stored in more refractory sediment P-fractions relative to potentially release-sensitive P-fractions. Intact sediment core experiments highlighted that the application of high areal loads of Phoslock® can, at least temporarily, significantly alter the vertical distribution of sediment dissolved oxygen concentrations and cycling of nutrients other than P, suggesting that the application of high areal loads of Phoslock® to lakes should be avoided. Disruption of internal P-loading in Loch Flemington (Inverness, UK) caused a significant reduction of in-lake P concentrations, a decrease of phytoplankton biomass and an increase in water clarity. The observed changes were generally comparable to those observed in long-term multi-lake studies investigating the recovery of shallow lakes following external P-load control, but occurred over a shorter time scale (1 year compared to decades). Alterations in ecological structure and function indicated that a change in state from a ‘phytoplankton dominated turbid state’ to a ‘macrophyte dominated clear water state’ was achieved in Loch Flemington. This study confirms that it is possible to force a state change in shallow lakes by disturbing feedback mechanisms and documents further work required to improve the efficacy of the Pcapping approach in lake remediation.

Η παρούσα έκθεση περιγράφει την Οικολογική Διαχείριση της Περιοχής της Λίμνης Καϊάφα, που ανήκει στο δίκτυο ΦΥΣΗ 2000. Η περιοχή έχει σπουδαία Οικοσυστήματα, με παραλιακή αμμόφιλη βλάστηση, παράκτια δάση πεύκης και λιμνοθαλάσσια βλάστηση. Υπάρχουν σημαντικοί τύποι οικοτόπων και παράλληλα έντονη ανθρώπινη επίδραση, τόσο λόγω των ιαματικών λουτρών όσο και λόγω της αναψυχής, στις εκτεταμένες αμμώδεις παραλίες. Ωστόσο, σημαντικό μέρος της περιοχής έχει καταστραφεί από τις τελευταίες πυρκαγιές. Ως εκ τούτου, παρατίθενται γενικά στοιχεία περιγραφής των υγροτόπων και του δικτύου ΦΥΣΗ (ΝΑΤURA) 2000, πλήρης περιγραφή του συγκεκριμένου οικοσυστήματος, αξιολόγηση των παραμέτρων, ανάλυση των επιδράσεων που δέχεται η περιοχή και προτάσεις διαχείρισης μέσω ενός προγράμματος παρακολούθησης. Στο τέλος της εργασίας παρατίθεται και ένα ένθετο φωτογραφιών της περιοχής. / The present diploma thesis, studies the Environmental Management of the Kaiafa Lake, located on West Peloponnese, Greece, which is included and protected by the Natura 2000 network. The specific area incorporates large Ecosystems with coastal vegetation, coastal pine forests and lagoon vegetation. The habitat, which is of significant importance, is strongly influenced by human interference, due to the sanative tourism and the extensive recreational works among the wide sandy beaches. Furthermore, a significant part of the area has been devastated by fire, during the past summer. This work provides a general description of Wetlands and Natura 2000 network of sites, a full description of the ecosystems, the effects of the reception area and an evaluation of proposals and management parameters as well, via a monitoring program.