| 1. |
- Moss, Brian D., et al.
(författare)
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Climate change and the future of freshwater biodiversity in Europe : a primer for policy-makers
- 2009
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Ingår i: Freshwater Reviews. - : Freshwater Biological Association. - 1755-084X. ; 2:2, s. 103-130
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Tidskriftsartikel (refereegranskat)abstract
- Earth's climate is changing, and by the end of the 21st century in Europe, average temperatures are likely to have risen by at least 2 °C, and more likely 4 °C with associated effects on patterns of precipitation and the frequency of extreme weather events. Attention among policy-makers is divided about how to minimise the change, how to mitigate its effects, how to maintain the natural resources on which societies depend and how to adapt human societies to the changes. Natural systems are still seen, through a long tradition of conservation management that is largely species-based, as amenable to adaptive management, and biodiversity, mostly perceived as the richness of plant and vertebrate communities, often forms a focus for planning. We argue that prediction of particular species changes will be possible only in a minority of cases but that prediction of trends in general structure and operation of four generic freshwater ecosystems (erosive rivers, depositional floodplain rivers, shallow lakes and deep lakes) in three broad zones of Europe (Mediterranean, Central and Arctic-Boreal) is practicable. Maintenance and rehabilitation of ecological structures and operations will inevitably and incidentally embrace restoration of appropriate levels of species biodiversity. Using expert judgement, based on an extensive literature, we have outlined, primarily for lay policy makers, the pristine features of these systems, their states under current human impacts, how these states are likely to alter with a warming of 2 °C to 4 °C and what might be done to mitigate this. We have avoided technical terms in the interests of communication, and although we have included full referencing as in academic papers, we have eliminated degrees of detail that could confuse broad policy-making
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| 2. |
- Norberg, Matilda, 1977-
(författare)
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A paleolimnological perspective on liming – implications for defining reference conditions in Swedish lakes
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Using paleolimnological techniques, I have studied surface-water acidification and the effects of liming in Swedish lakes on a decadal to millennial time-scale. The overall objective was to contribute to the discussion on the fulfilment of goals within the Swedish liming program. One of the main goals of this program is to restore lakes to natural or nearly natural conditions, i.e. to a reference condition as termed in the EU Water Framework Directive. In this context, a key issue is to define reference conditions. This is a central theme of my thesis, as lake sediments offer a unique way to study past lake conditions. Past lake-water acidity of 12 reference lakes in the Swedish liming program (ISELAW) was determined using diatom analysis of sediment cores. Pollen, lead, and flyash from coal/oil combustion were used as indicators of impact from land use and atmospheric pollution. A general trend in these lakes is an initial decline in pH after lake formation due to natural soil processes, which was then followed by rather low pH values (pH 5.3-6.5). In six of the lakes pH increased as a result of expansion of agriculture (burning, forest grazing) 2000 to 1000 years ago. Local mining and long-range airborne pollution have also impacted the lakes since medieval time. These results show that the conditions of the study lakes were not natural prior to industrialization and recent (20th century) acidification. The ISELAW lakes were selected on the basis of representing typical limed lakes, and they have been limed and monitored since at least the 1980s. A comparison of chemical/biological monitoring data and the paleolimnological data gives somewhat diverging results. Most of the monitoring data suggest that the lakes were subjected to acidification during the 20th century, but the paleolimnological data can only identify clear evidence of acidification in five of the 12 lakes, hence, all lakes were probably not recently acidified. According to conclusions from monitoring the lakes have recovered following liming. The paleolimnological data give a more complex picture and three different responses have been identified: 1) a return to a diatom composition found in the lake one hundred to several thousand years ago; 2) very small shifts in the diatom composition; or 3) a diatom composition previously not found in the lake. The latter response raised the question whether liming can cause an unnatural diatom community. A comparison of diatoms in surface sediment samples of 31 limed lakes with pre-industrial reference samples from 291 lakes showed that liming does not create an unnatural diatom composition. These results illustrate that the goals for liming were not reached in all of the limed lakes, and that paleolimnology can play an important role for assessments of acidification and liming. The comparative study also highlights the importance of designing monitoring programs that can produce reliable and long data series. Given the results of the paleolimnological investigations, it is obvious that we cannot assume that the 19th century represented a natural or near natural state, and thus is a realistic reference conditions. Natural long-term lake development and previous land-use impacts need to be considered in defining reference conditions. Neither can we disregard the fact that humans always will impact nature. Although paleolimnological studies are time consuming, I believe that they could be simplified to the extent that paleolimnology could become a routine method for environmental management.
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| 3. |
- Sayer, Carl D., et al.
(författare)
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The application of palaeolimnology to evidence-based lake management and conservation: examples from UK lakes
- 2012
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Ingår i: Aquatic conservation. - : John Wiley & Sons, Ltd. - 1052-7613 .- 1099-0755. ; 22:2, s. 165-180
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Tidskriftsartikel (refereegranskat)abstract
- * To help meet the requirements of water legislation, palaeolimnology has been widely used to establish ‘reference conditions’ and restoration targets for lakes. However, its potential for assessing the necessity and appropriateness of different lake management activities has been less publicized. * With reference to selected case studies covering consultancy projects commissioned by UK conservation agencies, this study highlights the important applied role of palaeolimnology. Using varying combinations of diatom, plant macrofossil and cladoceran analysis, the degree, timing and in many cases the likely drivers of ecological change were inferred for several lake sites. * From this basis advice was given on a range of lake management issues, including the need for sediment removal to combat eutrophication and/or the necessity of other nutrient reduction measures (Case study 1), the depth of sediment to be removed to maximize restoration potential through exposure of dormant banks of characean oospores (Case study 2), the requirement for fish management (Case study 3), and advice regarding fish farm expansion and licensing (Case study 4). Where possible management responses to the recommendations are outlined including any major outcomes. * All case studies illustrate the advantages, for lake management and conservation decision-making, of placing current lake ecological conditions in the context of long-term change. Copyright © 2012 John Wiley & Sons, Ltd.
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