| 1. |
- Dahl, Magnus, et al.
(författare)
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Is Lake Vänern well mixed? : A statistical procedure for selecting model structure and resolution
- 2004
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Ingår i: Journal of Great Lakes research. - 0380-1330. ; 30:2, s. 267-276
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Tidskriftsartikel (refereegranskat)abstract
- A statistical analysis of water quality data from Lake Vänern spanning three decades has been performed in order to establish an appropriate level of complexity for a water quality model. The analysis consists of paired t-tests for differences in the vertical direction and multiple comparison tests (Tukey's honestly significant difference criterion) for differences in the horizontal direction. The analysis indicates significant differences between the epi- and hypolimnion during stratified periods, but no significant differences in mixed periods. The two distinct basins are only marginally different. Furthermore, each basin can be considered well-mixed horizontally, except for parts located close to point emissions, or the particularly shallow regions.
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| 2. |
- Bryhn, Andreas, et al.
(författare)
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Ecosystem-based fisheries management is attainable, affordable, and should be viewed as a long-term commitment: Experiences from Lake Vattern, Sweden
- 2021
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Ingår i: Journal of Great Lakes Research. - : Elsevier BV. - 0380-1330. ; 47, s. 1437-1445
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Tidskriftsartikel (refereegranskat)abstract
- Lake Vattern is Sweden's second largest lake and faces multiple environmental challenges such as climate change, pollutants and invasive alien species. Since its foundation in 1957, the Lake Vattern Society of Water Conservation (LVSWC) has been a local actor aiming to manage a broad range of environmental issues concerning the lake and its catchment. Stakeholders can be members of LVSWC, which also organises a fisheries co-management group mainly dealing with fisheries issues. Ecosystem-based fisheries management (EBFM) is a widely desired framework shaped to focus on ecosystems, involve stakeholders, and address environmental issues in an adaptive, integrated and holistic manner while also including societal aspects. We have investigated how the management of Lake Vattern relates to 15 central principles for EBFM. The study found that LVSWC and the fisheries co-management group work along and towards the EBFM principles in a locally adapted way. Several environmental improvements have been observed concurrently with LVSWC activity, such as increased water clarity, and a strengthened stock of the Arctic char (Salvelinus alpinus). Long-term commitment by European, national and regional authorities was seen as essential to maintain and improve EBFM functions for Lake Vattern, to ensure continuity in the work, rather than having to depend on short projects. Becasue literature examples of EBFM in lakes are scarce worldwide, this study provides a unique example of the pursuit of EBFM in lake ecosystem management. (c) 2021 The Authors. Published by Elsevier B.V. on behalf of International Association for Great Lakes Research. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/ 4.0/).
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| 3. |
- Cazzaniga, Ilaria, et al.
(författare)
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Temporal changes in the remote sensing reflectance at Lake Vänern
- 2023
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Ingår i: Journal of Great Lakes research. - : Elsevier BV. - 0380-1330. ; 49:2, s. 357-367
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Tidskriftsartikel (refereegranskat)abstract
- The Aerosol Robotic Network - Ocean Color (AERONET-OC) instrument located at the Pålgrunden site in Lake Vänern provides values of remote sensing spectral reflectance RRS(λ) since 2008. These in situ RRS(λ) indicated a temporal increase from 2015 at center-wavelengths in the green and red spectral regions. To investigate the environmental and climate processes responsible for this increase, water color trends in Lake Vänern were analyzed considering in situ limnological measurements, meteo-climatic quantities and additionally satellite-derived data products from the Moderate Resolution Imaging Spectroradiometer on board the Aqua platform (MODIS-A). Satellite ocean color RRS(λ) data assessed against in situ RRS(λ) from the Pålgrunden site showed satisfactory agreement at a number of spectral bands. Relying on these validation results, comprehensive statistical analysis were performed using MODIS-A RRS(λ). These indicated periodical changes between 2002 and 2021 with clear minima occurring between 2010 and 2013. The complementary analyses of temporal changes characterizing limological and meteo-climatic quantities, and also relationships between these quantities and RRS(λ), indicated the existence of complex and concurrent bio-geochemical processes influencing water color in Lake Vänern. In particular, significant correlations were observed between RRS(λ) and turbidity, and also between RRS(λ) and total biovolume. Additionally, an early warming of Lake Vänern surface waters was identified since spring 2014. This occurrence could potentially affect the vertical mixing and water exchange between turbid coastal and pelagic waters with implications for phytoplankton phenology.
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| 4. |
- Futter, Martyn, et al.
(författare)
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Impacts of climate change on hydrology and water quality: Future proofing management strategies in the Lake Simcoe watershed, Canada
- 2013
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Ingår i: Journal of Great Lakes Research. - : Elsevier BV. - 0380-1330. ; 39, s. 19-32
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Tidskriftsartikel (refereegranskat)abstract
- The impacts of climate change on hydrology and water quality of the Black River, a tributary of Lake Simcoe, Canada, were assessed for the period 2001-2100, by integrating two models, HBV and INCA-P, and using statistically downscaled data from the Global Circulation Model CGCM3 for two IPCC scenarios (A1b and A2). The effectiveness of catchment management strategies was assessed across the 21st century by simulating controls on sewage treatment works and fertiliser applications, and implementing buffer strips and bank erosion controls. Both IPCC scenarios projected greatest precipitation increases during winter (highest in A2), and greatest rises in temperature during summer (highest in A1b) throughout the 21st century. Under both IPCC scenarios, the greater winter precipitation and warmer temperatures resulted both in higher winter flows and in an earlier spring snowmelt event Under scenario A2, the flow regime ceased to represent a river with a significant snowmelt influence by the 2090s. Increasing summer temperatures reduced summer flows (greater under A1b). Despite variability between IPCC scenarios, both projected increases in annual TP loadings into Lake Simcoe throughout the 21st century (greatest during winter). Management scenarios reduced, but did not fully compensate for, the impact of climate change upon Black River TP loads throughout the 21st century. Winter increases were still observed, due to high rainfall and flow. This climatic impact has significant implications for the current management plans which aim to reduce TP loads to the Lake by 30 tonnes. Mitigation strategies should therefore focus on methods for reducing TP loadings during wetter conditions. (c) 2012 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved.
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| 5. |
- Hammar, Johan, et al.
(författare)
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Smelt (Osmerus eperlanus): Glacial relict, planktivore, predator, competitor, and key prey for the endangered Arctic char in Lake Vättern, southern Sweden
- 2018
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Ingår i: Journal of Great Lakes Research. - : Elsevier BV. - 0380-1330. ; 44, s. 126-139
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Tidskriftsartikel (refereegranskat)abstract
- Smelts are crucial forage prey for many piscivorous fish species and have, as such, been frequently introduced outside their indigenous ranges, a management measure causing controversy, as smelts are also efficient predators and competitors. In Lake Vattern, relict Arctic char, fourhorn sculpin, smelt and seven species of crustaceans form a deep-water food-web, and interact closely as competitors, predators and prey. Here, we analyzed new and archived data back to the late 1960s in order to understand and relate observed life-history shifts in the smelt population, to concurrent adverse life-history changes observed in the endangered Arctic char population. Smelt growth was sigmoidal and the size frequency distribution dominated by fish up to 110 mm and age 0-4, although smelt occasionally reached 250 mm. Smelt diet shifts as the fish grow, from zooplankton, to Mysis relicta, to piscivory for individuals larger than 150 mm. Recruitment commonly demonstrates regular inter-annual pulses of YOY abundance although strong year classes produced during years with higher spring temperature cause post-annual irregularity of year class strength. Young smelt reside in surface water and older fish in deeper water. This ontogenetic shift in distribution depends on temperature occupied, prey availability and risk of inter- and intra-specific predation. Interestingly, even though very small Arctic char feed on smelt, most small Arctic char are found in deep water together with large smelt, and most large Arctic char are found in shallow water with small smelt. (C) 2017 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved.
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| 6. |
- Jenny, Jean Philippe, et al.
(författare)
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Scientists’ Warning to Humanity: Rapid degradation of the world's large lakes
- 2020
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Ingår i: Journal of Great Lakes Research. - : Elsevier BV. - 0380-1330. ; 46:4, s. 686-702
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Forskningsöversikt (refereegranskat)abstract
- © 2020 The Authors Large lakes of the world are habitats for diverse species, including endemic taxa, and are valuable resources that provide humanity with many ecosystem services. They are also sentinels of global and local change, and recent studies in limnology and paleolimnology have demonstrated disturbing evidence of their collective degradation in terms of depletion of resources (water and food), rapid warming and loss of ice, destruction of habitats and ecosystems, loss of species, and accelerating pollution. Large lakes are particularly exposed to anthropogenic and climatic stressors. The Second Warning to Humanity provides a framework to assess the dangers now threatening the world's large lake ecosystems and to evaluate pathways of sustainable development that are more respectful of their ongoing provision of services. Here we review current and emerging threats to the large lakes of the world, including iconic examples of lake management failures and successes, from which we identify priorities and approaches for future conservation efforts. The review underscores the extent of lake resource degradation, which is a result of cumulative perturbation through time by long-term human impacts combined with other emerging stressors. Decades of degradation of large lakes have resulted in major challenges for restoration and management and a legacy of ecological and economic costs for future generations. Large lakes will require more intense conservation efforts in a warmer, increasingly populated world to achieve sustainable, high-quality waters. This Warning to Humanity is also an opportunity to highlight the value of a long-term lake observatory network to monitor and report on environmental changes in large lake ecosystems.
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| 7. |
- Mc Callum, Erin
(författare)
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Fish living near two wastewater treatment plants have unaltered thermal tolerance but show changes in organ and tissue traits
- 2021
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Ingår i: Journal of Great Lakes Research. - : Elsevier BV. - 0380-1330. ; 47, s. 522-533
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Tidskriftsartikel (refereegranskat)abstract
- Municipal wastewater treatment plants (WWTPs) are a significant source of anthropogenic pollutants and are a serious environmental stressor in Laurentian Great Lakes ecosystems. In this study, we examined whether three freshwater fish species (bluegill sunfish Lepomis macrochirus, green sunfish Lepomis cyanellus, and round goby Neogobius melanostomus) collected near two wastewater effluent outflows in Lake Ontario showed altered measures of somatic investment and thermal tolerance. Fish of all three species collected near the WWTPs were larger with 50-60% heavier body masses compared to those collected at reference sites. Green sunfish had higher body condition and increased haematocrit at wastewater-contaminated sites, and both round goby and bluegill sunfish had larger livers (controlling for body mass) at wastewater-contaminated sites. Thermal tolerance (critical thermal maximum, CTmax) differed between species (green sunfish > bluegill sunfish > round goby), but was similar in fish collected at wastewater-contaminated sites compared to cleaner reference sites. Wastewater-contaminated sites had poorer water quality, higher nutrient loadings, and higher concentrations of anthropogenic contaminants (measured via polar organic chemical integrative samplers, POCIS) than reference sites. Our results suggest that fish in the wild may have some capacity to cope with WWTP effluent and avoid any potential impairments in thermal tolerance. Our findings also suggest that treated wastewater is changing water quality locally in Great Lakes watersheds, and that many fish species may be able to access extra nutrients provided by such effluent outflows. However, if outflow areas become preferred foraging areas this will inadvertently increase exposure to anthropogenic stressors and pollutants. Crown Copyright (C) 2021 Published by Elsevier B.V. on behalf of International Association for Great Lakes Research.
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| 8. |
- Milan, Manuela, et al.
(författare)
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Multiproxy reconstruction of a large and deep subalpine lake's ecological history since the Middle Ages
- 2015
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Ingår i: Journal of Great Lakes research. - : Elsevier. - 0380-1330. ; 41:4, s. 982-994
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Tidskriftsartikel (refereegranskat)abstract
- Two short sediment cores collected at the deepest points of the two sub-basins of Lake Garda (Northern Italy) were radiometrically dated and analyzed for geochemistry, spheroidal carbonaceous particles, photosynthetic pigments and diatoms aimed at reconstructing the lake's ecological evolution over the last ~700 years, and at defining its reference conditions. Both cores showed steady dominance of small Cyclotella spp. and oligotrophic diatom-inferred lake TP concentrations from the Middle Ages until the 1960s. During the successive decades, meso- to eutraphentic elongated Fragilariaceae increased at the expense of small centrics, and diatom-inferred TP concentrations increased. Independent records of subfossil pigments revealed higher pytoplankton biomass and abundance of cyanobacteria in both lake basins since the 1990s. Trends of biological proxies and reconstructed lake TP level agree with modern limnological data collected since the 1990s. Multivariate analyses outlined lake nutrient level as the principal driver of long-term trophic and diatom evolution of Lake Garda and suggested that decadal scale climate dynamics (i.e. air temperature, East Atlantic and North Atlantic Oscillation teleconnection indices) may indirectly modulate the nutrient-driven phytoplankton evolution. The comparison of the two cores revealed that only the larger lake basin responded to major hydrological changes in the catchment during the 1940s. The study emphasizes the vulnerability of large and deep subalpine lakes towards the steadily increasing anthropogenic pressures affecting such lakes, under the present context of global warming.
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| 9. |
- Naddafi, Rahmat
(författare)
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Stomach contents and stable isotopes analysis indicate Hemimysis anomala in Lake Ontario are broadly omnivorous
- 2018
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Ingår i: Journal of Great Lakes Research. - : Elsevier BV. - 0380-1330. ; 44, s. 467-475
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Tidskriftsartikel (refereegranskat)abstract
- Hemimysis anomala is a recent invader to North American aquatic ecosystems and is spreading rapidly throughout the Great Lakes region. This is the first littoral mysid in the North American Great Lakes; and, as such, the ecosystem effects are unknown and could be substantial. These effects depend on the role of Hemimysis in the food web and, therefore, on its diet. We examined the stomach contents of two life stages of Hemimysis from two sites in Lake Ontario during the growing season (May-November 2010). We also report the relationship between zooplankton hard parts and size for a number of potential prey species to allow the back-calculation of prey lengths from stomach contents. Both juvenile (2-5 mm) and adult Hemimysis (5-11 mm) were omnivorous, consuming phytoplankton, zooplankton, and benthos when available. However, adults appeared slightly more carnivorous and incorporated larger prey in their diets. Hemimysis were able to consume zooplankton prey up to 30% of their own length, including Bythotrephes longimanus and Cercopagis pengoi. Daphnia and Bosmina were selected over other prey by both juvenile and adult Hemimysis and were most common in stomachs during July and September when their abundances in the zooplankton were highest. Measurements of delta C-13 and delta N-15 corroborated stomach content materials, indicating an omnivorous diet which included benthic and pelagic sources. Omnivory by Hemimysis is typical of mysids in general and makes them less sensitive to seasonal dynamics of preferred prey items. (C) 2018 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved.
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| 10. |
- Oni, Stephen, et al.
(författare)
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Landscape-scale control of carbon budget of Lake Simcoe: A process-based modelling approach
- 2011
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Ingår i: Journal of Great Lakes Research. - : Elsevier BV. - 0380-1330. ; 37, s. 160-165
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Tidskriftsartikel (refereegranskat)abstract
- We present an application of the Integrated Catchments model for Carbon (INCA-C) to simulate dissolved organic carbon (DOC) dynamics in two main tributaries of Lake Simcoe. This is the first application of the INCA-C model to a large watershed with mixed agricultural, urban and forest land use. Understanding DOC dynamics in the Lake Simcoe watershed will aid in understanding the spatial and temporal patterns of organic and metal contaminant transport in the watershed which should, in turn, lead to improved watershed management. We were able to successfully simulate flows in the Beaver River and to capture the seasonal and inter-annual patterns in DOC concentration in the Beaver and White Creeks, two of Lake Simcoe's major tributaries. Sensitivity analysis showed the importance of hydrology and land use in controlling surface water DOC. The success of the model application presented here suggests that some of the same processes which control DOC in headwater watersheds are also operating in larger river basins. (C) 2010 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved.
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