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  • Blackwell Science Ltd  (8)
  • 1
    Electronic Resource
    Electronic Resource
    Phosphorus release from sediments in hardwater eutrophic lakes: the effects of redox-sensitive and -insensitive chemical treatments (2001)
    Oxford UK : Blackwell Science Ltd
    Freshwater biology 46 (2001), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Phosphorus (P) release from bottom sediments is an important source of nutrient enrichment in many lakes in sedimentary basins, such as those in western Canada. On the Boreal Plain, sediment P release is particularly strong during periods of seasonal anoxia.2. In this study, the effects of reduction–oxidation (redox)-sensitive and -insensitive chemicals on P release were examined in sediment cores collected from three eutrophic lakes.3. Contrary to expectations, redox-sensitive treatments were no more effective at lowering total phosphorus (TP) in sediment cores than some redox-insensitive treatments. Redox-sensitive treatments with FeCl3 and FeCl3 + O2 reduced TP to 8 and 6%, respectively, of reference concentrations, whereas redox-insensitive treatments with alum or lime + alum reduced TP to 14% of reference concentrations. Lime and O2 treatments reduced TP concentrations to 35 and 52% of reference concentrations, respectively.4. The fraction of P that adsorbed and co-precipitated with iron and aluminium in the sediment cores was low (non-apatite phosphorus fractions 〈 5%), suggesting that P release was controlled by apatite solubility and bacterial metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2001.00789.x
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  • 2
    Electronic Resource
    Electronic Resource
    Lime treatment and its effects on the chemistry and biota of hardwater eutrophic lakes (2001)
    Oxford UK : Blackwell Science Ltd
    Freshwater biology 46 (2001), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. The main focus of this study was to investigate the effects of single and multiple moderate doses of lime (slaked lime, Ca(OH)2, and/or calcite, CaCO3) on eutrophic hardwater lakes. This information would contribute to strategies to manage phytoplankton and macrophyte biomass in eutrophic lakes.2. Water chemistry and biota were monitored for up to 7 years after initial lime treatment and results were compared with reference systems.3. Complementary studies investigated the effect of lime on macrophytes in ponds, irrigation canals and microcosm experiments.4. When water pH was kept within its natural range (≤ 10), single and multiple lime applications to lakes and ponds controlled macrophyte biomass, without negatively affecting invertebrate communities.5. Single lime treatments at moderate dosages of lakes and ponds resulted in variable and mostly temporary changes in chlorophyll a (chl a) and phosphorus (P) concentration. Although sediment P release was reduced in single-dose lakes during the first winter following treatment, reductions appeared temporary.6. Multiple treatments of lakes and ponds were effective at reducing both chl a and P concentrations over longer periods. Mean winter P release rate was also reduced after initial treatment.7. In laboratory studies, sediment cores were incubated with eight different treatments to assess P release. Redox-sensitive treatments were no more effective at lowering total P concentration in overlying water than some redox-insensitive treatments. Lime reduced total P concentrations, but was not as effective as treatments with alum.8. The use of lime in managing macrophyte and phytoplankton biomass in shallow, hardwater lakes and ponds may be preferable over other treatments, because lime is economical and non-toxic as long as pH is kept within a natural range.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2001.00788.x
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of experimentally induced cyanobacterial blooms on crustacean zooplankton communities (2003)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 48 (2003), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY 1. Large in situ enclosures were used to study the effects of experimentally induced cyanobacterial blooms on zooplankton communities. A combination of N and P was added to shallow (2 m) and deep enclosures (5 m) with the goal of reducing the TN : TP ratio to a low level (∼5 : 1) to promote cyanobacterial growth. After nutrient additions, high biomass of cyanobacteria developed rapidly in shallow enclosures reaching levels only observed during bloom events in eutrophic lakes.2. In the shallow enclosures, particulate phosphorus (PP) was on average 35% higher in comparison with deep enclosures, suggesting that depth plays a key role in P uptake by algae. Phytoplankton communities in both deep and shallow enclosures were dominated by three cyanobacteria species –Aphanizomenon flos-aquae, Anabaena flos-aquae and Microcystis aeruginosa– which accounted for up to 70% of total phytoplankton biomass. However, the absolute biomass of the three species was much higher in shallow enclosures, especially Aphanizomenon flos-aquae. The three cyanobacteria species responded in contrasting ways to nutrient manipulation because of their different physiology.3. Standardised concentrations of the hepatotoxic microcystin-LR increased as a result of nutrient manipulations by a factor of four in the treated enclosures. Increased biomass of inedible and toxin producing cyanobacteria was associated with a decline in Daphnia pulicaria biomass caused by a reduction in the number of individuals with a body length of 〉1 mm. Zooplankton biomass did not decline at moderate cyanobacteria biomass, but when cyanobacteria reached high biomass large cladocerans were reduced.4. Our results demonstrate that zooplankton communities can be negatively affected by cyanobacterial blooms and therefore the potential to use herbivory to reduce algal blooms in such eutrophic lakes appears limited.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2003.01010.x
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of single Ca(OH)2 doses on phosphorus concentration and macrophyte biomass of two boreal eutrophic lakes over 2 years (2001)
    Oxford UK : Blackwell Science Ltd
    Freshwater biology 46 (2001), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Two hardwater eutrophic lakes of central Alberta were subjected to single doses of Ca(OH)2 (74 or 107 mg L–1). The effects of lime treatment on phosphorus (P) precipitation, sediment P release, and macrophyte biomass were assessed for up to 2 years.2. In both lakes, sediment P release was reduced to 16 and 27%, respectively, of pre-treatment values by the first winter following treatment. However, sediment P release returned to pre-treatment values during the following year.3. In contrast to these short-term effects, macrophyte biomass decreased by as much as 80% after lime application and remained there for at least 2 years.4. Our results indicate that a single dose of Ca(OH)2 may give short-term (〈 1 year) control of P and long-term control (〉 1 year) of macrophytes in hardwater eutrophic lakes of Alberta.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2001.00790.x
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  • 5
    Electronic Resource
    Electronic Resource
    Response of plankton communities to whole-lake Ca(OH)2 and CaCO3 additions in eutrophic hardwater lakes (2001)
    Oxford UK : Blackwell Science Ltd
    Freshwater biology 46 (2001), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. The impact of whole-lake lime (slaked lime, Ca(OH)2, and/or calcite, CaCO3) addition on plankton communities was evaluated in eutrophic hardwater lakes on the North American Boreal Plain.2. Two lakes received a single treatment of lime (Ca(OH)2 at 74 or 107 mg L–1), two lakes received multiple treatments with Ca(OH)2 and/or CaCO3 (5–78 mg L–1), and four lakes were untreated and served as reference systems.3. Over the long-term (〉 1 year), phytoplankton biomass was reduced in multiple-dose lakes, but not in single-dose lakes. Cyanobacteria typically dominated the algal community in the years before, during and after lime treatment in both single- and multiple-dose lakes.4. In the single-dose lakes, randomized intervention analysis showed no significant change in the biomass of zooplankton after lime addition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2001.00793.x
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  • 6
    Electronic Resource
    Electronic Resource
    Long-term effects of successive Ca(OH)2 and CaCO3 treatments on the water quality of two eutrophic hardwater lakes (2001)
    Oxford UK : Blackwell Science Ltd
    Freshwater biology 46 (2001), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Whole-lake experiments were conducted in two hardwater lakes (Halfmoon and Figure Eight) in Alberta, Canada, to investigate the effectiveness of repeated lime (slaked lime: Ca(OH)2 and/or calcite: CaCO3) treatments (5–78 mg L–1) for up to 7 years.2. Randomized intervention analysis of intersystem differences between the experimental and three reference lakes demonstrated a decline in euphotic total phosphorus and chlorophyll a concentrations in the experimental lakes after repeated lime treatments.3. After the second lime application to Halfmoon Lake, mean winter total phosphorus release rates (TPRR) decreased to 〈 1 mg m–2 day–1 compared with 3.6 mg m–2 day–1 during the winter after initial treatment. In the final year of lime application, mean summer TPRR decreased to 4.5 mg m–2 day–1 compared with 7.6 mg m–2 day–1 in the pre-treatment year.4. Mean macrophyte biomass declined and species composition was altered at 1 and 2 m depths in Figure Eight Lake during lime application. Over the first 6 years of treatment, macrophyte biomass at 2 m declined by 95% compared with concentrations recorded during the initial treatment year. In the last year of the study, macrophyte biomass at 2 m reached initial treatment concentrations, which coincided with the greatest water transparency. Over the treatment period, macrophyte species shifted from floating to rooted plants.5. Multiple lime applications can improve water quality in eutrophic hardwater lakes for periods of up to 7 years.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2001.00792.x
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  • 7
    Electronic Resource
    Electronic Resource
    The effects of lime addition on aquatic macrophytes in hard water: in situ and microcosm experiments (2001)
    Oxford UK : Blackwell Science Ltd
    Freshwater biology 46 (2001), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Aquatic macrophytes are abundant in ponds and canals that are constructed in semi-arid regions for water storage and conveyance, as well as in lakes that are culturally enriched.2. Addition of Ca(OH)2 to two hardwater ponds at 250 or 275 mg L–1 caused an immediate eradication of submersed aquatic plants. Although these ponds are well-buffered (alkalinity: 2.57–3.94 mequiv L–1; pH: 8.1–9.0), lime addition caused an immediate increase in pH of 0.2–3 units.3. Application of 135 mg L–1 Ca(OH)2 for 24 h or 210 mg L–1 Ca(OH)2 for 65 h to two irrigation canals had no effect on macrophyte biomass at the lower concentration and duration, but resulted in the elimination of aquatic macrophytes 1 month after the higher concentration, longer duration treatment.4. Unlike the macrophyte control achieved following application of 210–275 mg L–1 Ca(OH)2 to ponds or canals, microcosm experiments in which lime formulation [slaked lime (Ca(OH)2), calcite (CaCO3), or a 1 : 1 mixture] and concentrations (up to 1500 mg L–1) were manipulated failed to elicit a consistent change in macrophyte biomass. Macrophytes in microcosms treated for the short-term (23–33 days) with ≥ 200 mg L–1 Ca(OH)2 or a mixed Ca(OH)2/CaCO3 formulation always lost pigmentation, but biomass was not consistently reduced.5. Declines in macrophyte biomass following treatment of ponds and canals may have been triggered by a short-term rise in pH which, in these relatively warm (22–23 °C) alkaline (2.28–3.94 mequiv L–1) systems, would have resulted in low concentrations of free CO2 and bicarbonate for photosynthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2001.00794.x
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  • 8
    Electronic Resource
    Electronic Resource
    A stable carbon and nitrogen isotope study of lake food webs in Canada’s Boreal Plain (2001)
    Oxford UK : Blackwell Science Ltd
    Freshwater biology 46 (2001), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Stable carbon and nitrogen isotope and fish stomach content analyses were used to investigate food webs in five relatively undisturbed lakes on the Boreal Plain of Canada. Stable isotope analysis was also used to determine the importance of external and internal carbon sources.2. Overlap in the carbon and nitrogen signatures of primary producers made it difficult to determine unambiguously the feeding habits of many invertebrates. However, isotope analysis suggested that external carbon inputs were detectable in the aquatic food chains of the one lake with a short water residence time («1 year). In the other four lakes, with water residence times ≥1 year, autochthonous carbon was the only detectable carbon source in the food webs.3. Food webs in these lakes spanned a range of four to five trophic levels. Both invertebrates and fish appeared to eat a variety of food, often feeding at more than one trophic level.4. With the exception of one lake (SPH20), top predators in these lakes, northern pike (Esox lucius) and fathead minnows (Pimephales promelas), occupied similar trophic positions despite large differences in body size and trophic morphology. In SPH20, where there were two additional fish species, pike occupied a higher trophic position. However, all the top predators in each lake appeared to be omnivores and generalists.5. The prevalence of omnivory and the apparent generalist feeding habits of fish in these lakes suggest that organisms are flexible in their feeding habits and that these food webs will be resilient to disturbance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2001.00688.x
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