<p>Ekosystembaserad förvaltning bygger på en helhetlig syn på ekosystemen och dess förhållande till mänsklig aktivitet. Förvaltningsplanen för Barents hav utanför Norge är ett de längst framskridna försöken till implementering av denna förvaltningsmodell. Lång väg återstår dock för att uppnå de målsättningar som satts och särskilt gäller detta miljömålet för biologisk mångfald. Trots att fiskeri utpekats som den största påverkningsfaktorn på biologisk mångfald har det varit lite fokus på fiskeriernas negativa konsekvenser i arbetet med förvaltningsplanen. Den här uppsatsen försöker ge en bild av hur personer som jobbar inom förvaltningen ser på värdet med förvaltningsplanen, hur de uppfattar dess brister, och just varför de tror att fiskeriet negativa konsekvenser fått liten uppmärksamhet.</p><p>Helhetlighet och tvärsektoriellt samarbete kunde konkluderas som de främsta värdena med förvaltningsplanen. Organisationsproblem, konservatism och maktkamper ansågs dock skapa problem för implementering och samarbete över sektorerna, bland annat genom genom dålig kommunikation mellan utredningsgrupper och den implementerande organisationen. Konservatism och maktkamp uttrycktes i form av en ovillighet från andra att samarbeta över sektorerna, att bryta det sektoriella tankesättet, och en vilja att värna om sin maktsfär.  Strukturella problem lyftes även fram som en av de bakomliggande anledninganar till att fiskeriernas negativa effekter inte fått mer fokus. Starkt kulturellt fäste, fokus på petroleumsverksamhet och dålig kunskapsförmedling var andra faktorer som togs upp. </p> / <p>Ecosystem based management is a management approach that seeks to integrate ecological, social and economic goals. The Norwegian management plan for the Barents Sea is one of the most advanced attempts to ecosystem based management. There is, however, still a long way to go to achieve the goals that have been set. This is especially true for the environmental objective of biodiversity. Even though fishing activity has been pointed out as one of the main reasons for biodiversity loss, little attention has been drawn to this fact. This paper therefore tries to give the answer to the questions of how people working within the management perceive the plan; the core values of it, its flaws, and why they beleave that the negative consequenses of fisheries have been out of focus.</p><p> </p><p>The holistic viewpoint and the cooperation between the various sectors were the most emphazised values of the management plan. Organizational problems, conservatism, and power struggles were regarded as the main problems in trying to reach these goals. Lack of communication between  implementing bodies and investigating bodies was one example of this. Conservatism and power struggles were described as unwillingnes among individuals to adopt to the new intersectoral structures, and a wish to safeguard ones own power. The reason why the negative consequenses of fisheries have been out of focus, was also blamed on structural problems to a large extent. Other contributing factors were also the strong cultural role fisheries play in the norweigan society, the political focus on petroleum activity, and an insufficient spread of knowledge.</p>

Sustainability thinking has advanced considerably in the last few decades. Despite these advances, there remains a significant disconnect between thoughts and actions in this field. Sustainability metrics are one method proposed to help address this problem. A literature review of the most commonly used metrics and evaluation systems will first be presented, along with a critical evaluation of each system against the basic principles of sustainability. Next, a new evaluation framework will be proposed that addresses some of the shortcomings of the existing evaluation methods. This framework is designed to follow the best available thinking on a number of sustainability issues and overall, give a clear and concise evaluation of sustainability while still maintaining accuracy and scientific relevancy. Finally, a theoretical application of the framework to evaluating the sustainability of the city of Houston, Texas will be given, showing the necessary metrics required to follow the principles of the framework.

The Convention on Biological Diversity (CBD) promotes the Ecosystem Approach (EA). In this thesis it is analyzed how the EA approach could be applied to regional management of coastal areas in Sweden. The aim of this report is to compare management for preserving biodiversity on a landscape level in two regional coastal areas in Uppsala and Västra Götaland respectively. In Uppsala, one of the plans consists of a previous nature reserve and in Västra Götaland, a Regional landscape strategy has been established. The ecosystem approach is used as a theoretical framework in this thesis. More precisely, five EA operational guidelines have been used as analytical tools in the comparative approach adopted. The results show that the Västra Götaland Regional landscape strategy has been most consistent with the EA framework, since it fulfills three of the five operational guidelines while Gårdsskärskusten only accomplish two of the criteria. The social aspects are more central in the landscape strategy than in Gårdskärskusten, which is the main difference between the two plans. One area of inadequacy detected in the landscape strategy was the few identified aspects on maintenance of landscape connectivity features. The Regional landscape strategy could, if established in every county in Sweden, be a way to prevent the loss of biodiversity. However the plan needs to be supported by actions where preservation and utilization are integrated in an economic context. By considering nature protection as a development opportunity in strategic planning rather than as only a cost, important steps towards a sustainable future can be taken. / För att implementera målsättningarna i FN:s Konvention om Biologisk Mångfald har en ekosystemansats (EA) antagits och en viktig ekosystemtyp i Sverige där EA kan appliceras är kuster. Syftet med examensarbetet är att, med ekosystemansatsen som analysverktyg, studera hur och varför två planer för att bevara biologisk mångfald på landskapsnivå i två regionala kustområden i Uppsala län respektive Västra Götalands län skiljer sig åt. Planen består i Uppsala län av ett tilltänkt naturreservat och i Västra Götalands län av en Regional landskapsstrategi. Uppsatsens teoretiska förankring sker i ekosystemansatsen, med fokus på dess fem vägledande punkter och metodvalet är en jämförande design. Inom ramen för den jämförande designen har sedan en innehållsanalys samt kompletterande semistrukturerade intervjuer utförts. Resultatet visar att den Regionala landskapsstrategin i dagsläget är mer i linje med ekosystemansatsen, eftersom den uppfyller tre av fem vägledande punkter medan processen med Gårdsskärskusten enbart uppfyller två av fem vägledande punkter. I landskapsstrategin är sociala aspekter centrala och det är en förklaring till varför de olika planerna skiljer sig åt. Intressant är dock att betoningen på aktörsinvolvering verkar leda till att vissa ekologiska grundprinciper som konnektivitet i landskapet tonas ned, vilka är framträdande i processen med Gårdskärskusten. Regionala landskapsstrategier kan enligt min mening innebära ett stort steg mot att hindra förlusten av biologisk mångfald i Sverige om de uppförs i varje län. Inom landskapsstrategierna är det vidare essentiellt att skyddade områden, som exempelvis Gårdsskärskusten, också inkorporerar ett landskapsstrategitänk och i många fall innebär det att skötselåtgärder fortsätter att utföras. Svårigheten kan dock vara hur finansieringen av skötseln skall ske men där finns alternativa inkomstmöjligheter, från exempelvis naturturism och stresshantering på företag, som behöver utvecklas ytterligare.

<p>Coal fired power plants are ubiquitous in the United States and most developed countries around the world, providing affordable electricity to consumers. In the US, approximately six hundred power plants generate 136 million tons of Coal Combustion Residuals (CCRs) annually, encompassing fly ash, bottom ash, and flue gas desulfurization materials. The range and blends of CCRs varies substantially across coal-fired plants and depends on a unique set of circumstances for each plant and coal source. Current U.S. regulations mandate the installation of advanced capture technologies to reduce atmospheric pollution, but do not address the transfer and storage, or the potential impacts to water resources. Thus improved air quality is traded for significant enrichments of contaminants in the solid waste and effluent discharged from power plants. </p><p>This work examines the geochemical and isotopic characteristics of CCRs, as well as potential environmental impacts from CCRs. This investigation looks at several different aspects of CCR and environmental interactions from 1) the immediate impacts of the 2008 TVA coal ash spill in Kingston, TN, 2) the long-term (18-month) exposure of the spilled ash in the Emory and Clinch rivers, 3) impacts on waterways in North Carolina that receive CCR effluent from coal fired power plants, and 4) examination of boron and strontium isotopes of CCRs from leaching experiments and their application as tracers in the environment of the TVA spill and NC waterways. These investigations have illuminated several conclusions, including contact of surface water with CCRs leach high concentrations of leachable CCR contaminants, such as As, Se, B, Sr, Mo, and V in the surface waters; the dilution effect is critical in determining the concentration of contaminants from the CCRs in surface water (both at the spill and in waterways receiving CCR effluent); recycling of trace elements (such as As) through adsorption/desorption can impact water quality; and elevated boron and strontium concentrations, in addition to their isotopes, can trace CCR effluent in the environment. Combining the geochemical behavior and isotopic characteristics provides a novel tool for the identification CCR effluents in the environment.</p> / Dissertation

Lake Malawi is the second largest lake in Africa, supporting diverse populations of endemic cichlids and supplying essential water resources to Malawi, Mozambique and Tanzania. However, population growth, rapid deforestation and intensive agriculture, especially in the southern catchments, have accelerated soil erosion during the last half century. These anthropogenically-disturbed catchments have caused rivers to transport greater sediment loads into Lake Malawi than rivers within forested catchments. Lake Malawi?s immense size and oligotrophic nature may retard detection of inputs of external contaminants. Reversing the effects of increased nutrient loading to Lake Malawi once observed would likely take generations, as the residence time of water is over 140 years. Therefore, sensitive metrics are required to assess the effects of land use change and climate variability in Lake Malawi in advance of deleterious effects. In this study, paleolimnological analyses of four sediment cores collected in 1997 and 1998 along a longitudinal transect of Lake Malawi, dated with ²¹⁰Pb analyses and analyzed for biogenic silica and sedimentary diatom assemblages, were used to create a long-term water quality dataset. These four sites span gradients of land use and latitude in order to reconstruct limnological conditions over the whole lake during the last 300 years. Paleoecological results indicate that patterns of diatom assemblage change are not uniform lake wide. Southern cores contain evidence of nutrient enrichment starting as early as ca. 1940, indicated by increased silica, carbon and nitrogen burial. By ca. 1970, increased rates of sedimentation, diatom influx and changes in diatom community composition, characterized by increased percent abundance of eutrophic diatom taxa, are attributable to accelerated enrichment by terrestrial soil erosion. The succession of diatoms in southern Lake Malawi begins with high percent abundance of <i>Aulacoseira nyassensis</i> and <i>Fragilaria africana</i>, which thrive in nutrient-rich waters, followed by a shift towards diatom taxa with reduced silica requirements by ca. 1980 (e. g. <i>Stephanodiscus nyassae, S. minutulus, S. muelleri, Cyclostephanos</i> and small <i>Nitzschia</i> species. ), a pattern comparable to the eutrophication-induced decline in silica to phosphorus ratios in Lake Victoria. In Lake Malawi, evidence of eutrophication extends to the mid lake as indicated by similar diatom assemblage changes in the sediment core from the central region. Diatom stratigraphies from the north end of the lake indicate no observable impacts of land use change on the northern basin of Lake Malawi during the past 350 years. However, a nine-meter rise in water level ca. 1860 AD appears to have resulted in elevated diatom influxes at that time comparable to the recent eutrophication-induced diatom influxes of the southern cores. The effects of this rise in water level was recorded in all three measured sites, southern, central and northern Lake Malawi, indicating lake-wide increased productivity, yet changes to the diatom community composition were imperceptible. This study shows evidence of recent cultural eutrophication altering limnological conditions with impacts to the biogeochemical cycling of silica, the available silica to phosphorus ratios and the biotic communities of a large portion of Lake Malawi. Thus, providing an early warning that proper stewardship of Lake Malawi requires effective management of land-use practices within the catchment to reduce soil erosion and avoid widespread water quality deterioration of this great lake.

Part of a cutover bog in Pokesudie Island, New Brunswick, Canada was contaminated with seawater and was still largely devoid of vegetation 5 years after the event and was consequently chosen for study. The study area consisted of rectangular fields with cambered surface that sloped down (2%) to the drainage ditches on both sides. Across this slope zones were created: Up-, Mid- and Low- areas on either side of the centerline of fields. Two field experiments were conducted to determine abiotic stresses to plant re-establishment in terms of hydrology and peat characteristics along this cambered surface. The general objective was to identify microsites or zones that could be suitable to the introduction of wetland halophytes <em>Juncus balticus</em> Willd. and <em>Spartina pectinata</em> Link obtained from nearby salt marshes. <br /><br /> In the first experiment, cylindrical <em>J. balticus</em> sods were transplanted into the Up- and Low- areas, at 1, 3, 5, 10 and 20 d of incubation (in May 2005) with measurements made on the Outer and Inner annular sod sections, replicated over 4 blocks. Moisture (% dry weight basis (dwb)) reached maximum values 1 day after transplantation, 84±0. 05 for Outer and 103±0. 07 for Inner sod section. Salinity (dS m^-1) in sods due to ingress of sodium (Na⁺ ) and chloride (Cl^-) reached values of the surrounding peat 3 days after transplantation, 3. 52±1. 06 for Inner sod section and 4. 11±0. 99 for Outer sod section in Up-areas, and 1. 76±0. 24 for Inner sod section and 2. 57±0. 28 for Outer sod section in Low-areas. Maximum decrease in pH was at 5 days after transplantation, in Outer sod section in the Up-areas (from 5. 89 to 4. 88±0. 14) which was much higher than the pH range of 3-4 of the surrounding peat. This was due to the buffering capacity of calcium (Ca²⁺) and magnesium (Mg²⁺) in sods which did not change in concentration after 20 days of incubation. Therefore, Inner sod sections were less affected by the surrounding peat compared to the Outer sod sections, suggesting that a larger sod volume may alleviate stressful conditions for a longer time at transplantation and consequently allow greater time for adaptation. <br /><br /> In the second experiment, <em>J. balticus</em> and <em>S. pectinata</em> were transplanted on the 3 Locations Up-, Mid- and Low- areas, replicated over 10 blocks; and peat characteristics were measured at Depths 0-5, 5-10, 10-15 and 15-20 cm 5 times during the study period May-August 2005. Survival of <em>J. balticus</em> was poorest (27. 5±8. 3 %) in the Low-areas compared to 68. 5±8. 9 % in the Up- and 58. 5±8. 7% in the Mid- areas. <em>S. pectinata</em> survival was very good at all Locations (89±5. 3, 91. 6±3. 1 and 84. 2±4. 4 for Up-, Mid- and Low- areas, respectively) having better adaptation to early season waterlogged conditions. Waterlogged conditions resulted from a perched water table during the early part of the growing season (May-June) and were alleviated only upon the complete thaw of the frozen peat layer on 8 July. Thereafter, important changes in hydrology and peat characteristics occurred: water table depths decreased from -8. 5±1. 7 and -1. 6±1. 2 cm on 26 May, to -51. 5±2. 5 and -40. 7±2. 4 cm by 9 August in Up- and Low-areas, respectively; redox potentials at 12 cm depth increased from 26 June (190. 9±8, 175±10. 8 and 109. 2±29. 4 mV) to 9 August (282. 8±8, 302. 8±14. 3 and 312. 3±29. 6 mV) in the Up-, Mid- and Low-areas, respectively which showed that anaerobic conditions were maintained throughout the study period; decreased moisture content from 1256. 8±61. 9, 1667. 4±126. 3 and 1728. 6±153 on 30 May, to 851. 7±21. 2, 874. 6±47 and 1008. 2±57. 5 % dwb on 25 July) which caused increased dry bulk density (from 0. 07±0. 002, 0. 06±0. 003 and 0. 07±0. 01 to 0. 09±0. 003, 0. 09±0. 005 and 0. 08±0. 004) in the Up-, Mid- and Low-areas, respectively; and increased electrical conductivity (salinity) especially on the 0-5cm surface (from 1. 9±0. 13, 1. 8±0. 31 and 1. 5±0. 29 to 18±1. 9, 17. 5±1. 1 and 12. 2±1 dS m^-1) which also caused decreased pH (from 3. 5±0. 04, 3. 5±0. 08 and 3. 6±0. 01 to 2. 85±0. 04, 2. 85±0. 01 and 2. 9±0. 03) in the Up-, Mid- and Low-areas, respectively. Therefore, spring flooding followed by high surface salinity in summer precludes plant establishment by seeding and explains the current lack of spontaneous revegetation. Waterlogged conditions were of greater magnitude and duration at lower elevation areas unfavourable to <em>J. balticus</em> survival but salinity levels were high in the Up- and Mid-areas. <br /><br /> In the subsequent part of the second experiment, plants of <em>J. balticus</em> and <em>S. pectinata</em> grown in the study area and those collected from marshes were divided into above- and below- ground parts and accumulation of salt ions in plant tissues were determined to understand the species' salt-tolerance mechanism, as well as the accumulation of potentially toxic levels of iron (Fe) and manganese (Mn). Both plant species had similar accumulations (mmol kg^-1 dry wt,) of Na⁺ (474. 3±41 and 468. 3±31. 7, respectively) and Cl^- (314. 9±21. 9 and 310. 5±27. 5, respectively) in the above-ground parts but differed in how they managed Na⁺. <em>J. balticus</em> accumulated more Na⁺ in below-ground parts (659. 3±88. 7) and had limited transport to the above-ground parts, while <em>S. pectinata</em> accumulated and excreted Na⁺ in the above-ground parts and had less accumulation in the below-ground parts (397. 4±25. 1). <em>S. pectinata</em> maintained (313. 1±23. 8 in marsh <em>vs. </em> 292. 4±26. 2 in bog) and <em>J. balticus</em> increased (84. 2±1. 2 in marsh <em>vs. </em> 531. 2±38. 6 in bog) K⁺-selectivity in the shoots, a key requirement for survival in saline conditions. Compared with their respective marsh plants, <em>S. pectinata</em> had more salinity-tolerance than <em>J. balticus</em> primarily through its maintenance of Ca²⁺ (21. 5±1. 7 in marsh <em>vs. </em> 35. 6±3. 8 in bog) compared to a decrease in <em>J. balticus</em> (144. 7±12. 5 in marsh <em>vs. </em> 41±3. 7 in bog). Furthermore, Fe and Mn uptake in both species decreased but reached critical Fe-deficiency levels (1. 1±0. 1 mmol kg^-1 dry wt,) only in <em>S. pectinata</em> grown in drier areas. <br /><br /> It is concluded that local conditions of waterlogging (especially in lower elevation areas) and high salinity and low pH (notably in the upper elevation areas) were favourable to the survival of <em>S. pectinata</em> in all areas and <em>J. balticus</em> only in upper elevation areas. Sod transplanting may alleviate the acidity problem and depending on sod volume may delay the effects of harsh conditions of the cutover bog. However, long-term survival and growth of both species in drier areas may be constrained by deficiency in calcium in <em>J. balticus</em> and iron in <em>S. pectinata</em>.

Since their introduction to Lake Erie, dreissenid mussels may have reengineered the cycling of nutrients in the lake so that the nearshore benthic community intercepts, retains, and recycles greater quantities of nutrients. This study traces particulate matter on a basin scale by characterizing the chemical composition (POC and PN concentrations, POC/PN mass ratios, &delta;¹³C and &delta;¹⁵N) of suspended particulate matter in Lake Erie, three tributary inflows, and the lake outflow between May and October, 2002. The data are used to 1) determine the relative contributions of allochthonous and autochthonous sources to suspended particulate matter, 2) identify possible sources of suspended particulate matter, and 3) compare suspended particulate matter in the eastern basin of Lake Erie with that in the central and western basins. Mean POC concentrations range from 175 to 4494 µg/L and mean PN concentrations range from 33 to 812 µg/L in this system. Mean POC/PN mass ratios are similar across all sampling locations, ranging between 4. 5 and 6. 9, and indicate that suspended particulate matter at these sites is mainly derived from autochthonous sources, particularly plankton. The ranges of &delta;¹³C (-34 to -22 ?) and &delta;¹⁵N (1 to 12 ?) identify terrestrial plants and soil matter, aquatic macrophytes, phytoplankton, and sewage as possible sources of suspended particulate matter at all sites. Plankton is probably the dominant source of suspended particulate matter at each site, with smaller contributions from allochthonous and other autochthonous sources. Significant differences in the concentration and isotope data between inflow and lake or outflow sites indicate that tributary inflows may receive greater contributions from terrestrial plants and soils and aquatic macrophytes than the lake and outflow. &delta;¹⁵N signatures also identify animal manure as a possible source of suspended particulate matter at the inflows. PN concentrations and &delta;¹⁵N signatures suggest that the shallowest nearshore sites close to Peacock Point in the eastern basin receive PN from a source that is not present at the other eastern basin sites or at the sites in the central and western basins. This source may be related to dreissenid mussels at these nearshore sites recycling nitrogen back into the water column.

Naphthenic acids (NAs) are carboxylated alkanes and cycloalkanes concentrated in wastewater during oil sands processing. The general chemical formula is C{n}H{n+Z}O{2}, where n represents the number of carbon atoms and Z specifies a homologous family with 0-6 rings (Z=0 to Z=-12). The wastewater is acutely toxic to surface water organisms and is stored in tailings ponds with over 230 million m³ of fines tailings and free water. The purpose of this thesis was to provide a preliminary evaluation of the potential attenuation of NAs during groundwater flow from the ponds. Laboratory studies were conducted to evaluate possible attenuation mechanisms. Aerobes from aquifer material degraded 60% of the NAs over 20 weeks in laboratory microcosms. The greatest decrease occurred in the low molecular weight bicyclic homologues with 12 to 16 carbons. The microbial activity confirms that aerobic naphthenate-degrading bacteria occur naturally in the glacial aquifer near Suncor's Pond 2/3. These results support the hypothesis that limited aerobic biodegradation of the smaller components of NAs could occur relatively rapidly under field conditions. There was no measurable decrease in NA concentration over six months in anaerobic microcosms, although microbial activity did lead to sulfate-reducing and methanogenic conditions. The theoretical retardation in glacio-fluvial sands was calculated using soil-water partitioning coefficients (K{d}) determined by batch equilibration experiments using a mixture of naturally occurring naphthenic acids as well as the nine surrogates. The retardation (porosity of 0. 3, bulk density of 1. 5 g/mL) ranged from 1. 2 to 2. 6. However, no measurable sorption was seen at the field sites. Detailed characterization allows us to examine how the proportions of homologue, or groups of molecules with the same molecular weight and number of cycloalkane rings, vary. Aerobic biodegradation favoured removal of low molecular weight NAs. A 15% mass loss attributed to sorption caused no changes in the 3D signature. Thus, changes in NA "signature" in groundwater systems were then attributed to aerobic biodegradation. Three plumes were examined for evidence of attenuation of NAs via biodegradation. First, the individual samples were classified as background, possibly process-affected or process-affected using a combination of Piper diagrams, the stable isotopes oxygen-18 and deuterium, dissolved chloride and sodium, as well as the total naphthenic acids concentration. Second, in order to estimate attenuation due to dispersive dilution, a linear correlation line was drawn between various conservative tracers and the naphthenic acids concentration. This allowed the identification of certain samples as possibly having a lower concentration of NAs than could be expected from simple dispersive dilution. Third, the 3D signature of certain samples were examined for the presence of the aerobic biodegradation 3D signature. One site showed good evidence for aerobic biodegradation of naphthenic acids. A second site showed some evidence for biodegradation under methanogenic conditions but the evidence was not definitive. The evidence at the third site was contradictory and no conclusions could be drawn from it. This research suggests some attenuation of NAs by biodegradation may be possible during groundwater flow.

Lake Malawi is the second largest lake in Africa, supporting diverse populations of endemic cichlids and supplying essential water resources to Malawi, Mozambique and Tanzania. However, population growth, rapid deforestation and intensive agriculture, especially in the southern catchments, have accelerated soil erosion during the last half century. These anthropogenically-disturbed catchments have caused rivers to transport greater sediment loads into Lake Malawi than rivers within forested catchments. Lake Malawi?s immense size and oligotrophic nature may retard detection of inputs of external contaminants. Reversing the effects of increased nutrient loading to Lake Malawi once observed would likely take generations, as the residence time of water is over 140 years. Therefore, sensitive metrics are required to assess the effects of land use change and climate variability in Lake Malawi in advance of deleterious effects. In this study, paleolimnological analyses of four sediment cores collected in 1997 and 1998 along a longitudinal transect of Lake Malawi, dated with ²¹⁰Pb analyses and analyzed for biogenic silica and sedimentary diatom assemblages, were used to create a long-term water quality dataset. These four sites span gradients of land use and latitude in order to reconstruct limnological conditions over the whole lake during the last 300 years. Paleoecological results indicate that patterns of diatom assemblage change are not uniform lake wide. Southern cores contain evidence of nutrient enrichment starting as early as ca. 1940, indicated by increased silica, carbon and nitrogen burial. By ca. 1970, increased rates of sedimentation, diatom influx and changes in diatom community composition, characterized by increased percent abundance of eutrophic diatom taxa, are attributable to accelerated enrichment by terrestrial soil erosion. The succession of diatoms in southern Lake Malawi begins with high percent abundance of <i>Aulacoseira nyassensis</i> and <i>Fragilaria africana</i>, which thrive in nutrient-rich waters, followed by a shift towards diatom taxa with reduced silica requirements by ca. 1980 (e. g. <i>Stephanodiscus nyassae, S. minutulus, S. muelleri, Cyclostephanos</i> and small <i>Nitzschia</i> species. ), a pattern comparable to the eutrophication-induced decline in silica to phosphorus ratios in Lake Victoria. In Lake Malawi, evidence of eutrophication extends to the mid lake as indicated by similar diatom assemblage changes in the sediment core from the central region. Diatom stratigraphies from the north end of the lake indicate no observable impacts of land use change on the northern basin of Lake Malawi during the past 350 years. However, a nine-meter rise in water level ca. 1860 AD appears to have resulted in elevated diatom influxes at that time comparable to the recent eutrophication-induced diatom influxes of the southern cores. The effects of this rise in water level was recorded in all three measured sites, southern, central and northern Lake Malawi, indicating lake-wide increased productivity, yet changes to the diatom community composition were imperceptible. This study shows evidence of recent cultural eutrophication altering limnological conditions with impacts to the biogeochemical cycling of silica, the available silica to phosphorus ratios and the biotic communities of a large portion of Lake Malawi. Thus, providing an early warning that proper stewardship of Lake Malawi requires effective management of land-use practices within the catchment to reduce soil erosion and avoid widespread water quality deterioration of this great lake.

Part of a cutover bog in Pokesudie Island, New Brunswick, Canada was contaminated with seawater and was still largely devoid of vegetation 5 years after the event and was consequently chosen for study. The study area consisted of rectangular fields with cambered surface that sloped down (2%) to the drainage ditches on both sides. Across this slope zones were created: Up-, Mid- and Low- areas on either side of the centerline of fields. Two field experiments were conducted to determine abiotic stresses to plant re-establishment in terms of hydrology and peat characteristics along this cambered surface. The general objective was to identify microsites or zones that could be suitable to the introduction of wetland halophytes <em>Juncus balticus</em> Willd. and <em>Spartina pectinata</em> Link obtained from nearby salt marshes. <br /><br /> In the first experiment, cylindrical <em>J. balticus</em> sods were transplanted into the Up- and Low- areas, at 1, 3, 5, 10 and 20 d of incubation (in May 2005) with measurements made on the Outer and Inner annular sod sections, replicated over 4 blocks. Moisture (% dry weight basis (dwb)) reached maximum values 1 day after transplantation, 84±0. 05 for Outer and 103±0. 07 for Inner sod section. Salinity (dS m^-1) in sods due to ingress of sodium (Na⁺ ) and chloride (Cl^-) reached values of the surrounding peat 3 days after transplantation, 3. 52±1. 06 for Inner sod section and 4. 11±0. 99 for Outer sod section in Up-areas, and 1. 76±0. 24 for Inner sod section and 2. 57±0. 28 for Outer sod section in Low-areas. Maximum decrease in pH was at 5 days after transplantation, in Outer sod section in the Up-areas (from 5. 89 to 4. 88±0. 14) which was much higher than the pH range of 3-4 of the surrounding peat. This was due to the buffering capacity of calcium (Ca²⁺) and magnesium (Mg²⁺) in sods which did not change in concentration after 20 days of incubation. Therefore, Inner sod sections were less affected by the surrounding peat compared to the Outer sod sections, suggesting that a larger sod volume may alleviate stressful conditions for a longer time at transplantation and consequently allow greater time for adaptation. <br /><br /> In the second experiment, <em>J. balticus</em> and <em>S. pectinata</em> were transplanted on the 3 Locations Up-, Mid- and Low- areas, replicated over 10 blocks; and peat characteristics were measured at Depths 0-5, 5-10, 10-15 and 15-20 cm 5 times during the study period May-August 2005. Survival of <em>J. balticus</em> was poorest (27. 5±8. 3 %) in the Low-areas compared to 68. 5±8. 9 % in the Up- and 58. 5±8. 7% in the Mid- areas. <em>S. pectinata</em> survival was very good at all Locations (89±5. 3, 91. 6±3. 1 and 84. 2±4. 4 for Up-, Mid- and Low- areas, respectively) having better adaptation to early season waterlogged conditions. Waterlogged conditions resulted from a perched water table during the early part of the growing season (May-June) and were alleviated only upon the complete thaw of the frozen peat layer on 8 July. Thereafter, important changes in hydrology and peat characteristics occurred: water table depths decreased from -8. 5±1. 7 and -1. 6±1. 2 cm on 26 May, to -51. 5±2. 5 and -40. 7±2. 4 cm by 9 August in Up- and Low-areas, respectively; redox potentials at 12 cm depth increased from 26 June (190. 9±8, 175±10. 8 and 109. 2±29. 4 mV) to 9 August (282. 8±8, 302. 8±14. 3 and 312. 3±29. 6 mV) in the Up-, Mid- and Low-areas, respectively which showed that anaerobic conditions were maintained throughout the study period; decreased moisture content from 1256. 8±61. 9, 1667. 4±126. 3 and 1728. 6±153 on 30 May, to 851. 7±21. 2, 874. 6±47 and 1008. 2±57. 5 % dwb on 25 July) which caused increased dry bulk density (from 0. 07±0. 002, 0. 06±0. 003 and 0. 07±0. 01 to 0. 09±0. 003, 0. 09±0. 005 and 0. 08±0. 004) in the Up-, Mid- and Low-areas, respectively; and increased electrical conductivity (salinity) especially on the 0-5cm surface (from 1. 9±0. 13, 1. 8±0. 31 and 1. 5±0. 29 to 18±1. 9, 17. 5±1. 1 and 12. 2±1 dS m^-1) which also caused decreased pH (from 3. 5±0. 04, 3. 5±0. 08 and 3. 6±0. 01 to 2. 85±0. 04, 2. 85±0. 01 and 2. 9±0. 03) in the Up-, Mid- and Low-areas, respectively. Therefore, spring flooding followed by high surface salinity in summer precludes plant establishment by seeding and explains the current lack of spontaneous revegetation. Waterlogged conditions were of greater magnitude and duration at lower elevation areas unfavourable to <em>J. balticus</em> survival but salinity levels were high in the Up- and Mid-areas. <br /><br /> In the subsequent part of the second experiment, plants of <em>J. balticus</em> and <em>S. pectinata</em> grown in the study area and those collected from marshes were divided into above- and below- ground parts and accumulation of salt ions in plant tissues were determined to understand the species' salt-tolerance mechanism, as well as the accumulation of potentially toxic levels of iron (Fe) and manganese (Mn). Both plant species had similar accumulations (mmol kg^-1 dry wt,) of Na⁺ (474. 3±41 and 468. 3±31. 7, respectively) and Cl^- (314. 9±21. 9 and 310. 5±27. 5, respectively) in the above-ground parts but differed in how they managed Na⁺. <em>J. balticus</em> accumulated more Na⁺ in below-ground parts (659. 3±88. 7) and had limited transport to the above-ground parts, while <em>S. pectinata</em> accumulated and excreted Na⁺ in the above-ground parts and had less accumulation in the below-ground parts (397. 4±25. 1). <em>S. pectinata</em> maintained (313. 1±23. 8 in marsh <em>vs. </em> 292. 4±26. 2 in bog) and <em>J. balticus</em> increased (84. 2±1. 2 in marsh <em>vs. </em> 531. 2±38. 6 in bog) K⁺-selectivity in the shoots, a key requirement for survival in saline conditions. Compared with their respective marsh plants, <em>S. pectinata</em> had more salinity-tolerance than <em>J. balticus</em> primarily through its maintenance of Ca²⁺ (21. 5±1. 7 in marsh <em>vs. </em> 35. 6±3. 8 in bog) compared to a decrease in <em>J. balticus</em> (144. 7±12. 5 in marsh <em>vs. </em> 41±3. 7 in bog). Furthermore, Fe and Mn uptake in both species decreased but reached critical Fe-deficiency levels (1. 1±0. 1 mmol kg^-1 dry wt,) only in <em>S. pectinata</em> grown in drier areas. <br /><br /> It is concluded that local conditions of waterlogging (especially in lower elevation areas) and high salinity and low pH (notably in the upper elevation areas) were favourable to the survival of <em>S. pectinata</em> in all areas and <em>J. balticus</em> only in upper elevation areas. Sod transplanting may alleviate the acidity problem and depending on sod volume may delay the effects of harsh conditions of the cutover bog. However, long-term survival and growth of both species in drier areas may be constrained by deficiency in calcium in <em>J. balticus</em> and iron in <em>S. pectinata</em>.