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  • 1
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    Historical trends in lake and river ice cover in the northern hemisphere (2000)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2000-09-08
    Description: Freeze and breakup dates of ice on lakes and rivers provide consistent evidence of later freezing and earlier breakup around the Northern Hemisphere from 1846 to 1995. Over these 150 years, changes in freeze dates averaged 5.8 days per 100 years later, and changes in breakup dates averaged 6.5 days per 100 years earlier; these translate to increasing air temperatures of about 1.2 degrees C per 100 years. Interannual variability in both freeze and breakup dates has increased since 1950. A few longer time series reveal reduced ice cover (a warming trend) beginning as early as the 16th century, with increasing rates of change after about 1850.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Magnuson -- Robertson -- Benson -- Wynne -- Livingstone -- Arai -- Assel -- Barry -- Card V -- Kuusisto -- Granin -- Prowse -- Stewart -- Vuglinski -- New York, N.Y. -- Science. 2000 Sep 8;289(5485):1743-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Limnology, University of Wisconsin-Madison, Madison, WI 53706, USA. U.S. Geological Survey, Water Resources Division, 8505 Research Way, Middleton, WI 53562, USA. Department of Forestry, Virginia Polytechnic Institute and State Unive.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10976066" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
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    Ecology and conservation. Whose fish are they anyway? (2001)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2001-08-18
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Magnuson, J J -- Safina, C -- Sissenwine, M P -- New York, N.Y. -- Science. 2001 Aug 17;293(5533):1267-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Limnology, University of Wisconsin, Madison, WI 53706, USA. jmagnuson@mhub.limnology.wisc.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11509715" target="_blank"〉PubMed〈/a〉
    Keywords: Animal Identification Systems ; Animals ; Atlantic Ocean ; *Behavior, Animal ; Body Temperature ; *Conservation of Natural Resources ; Diving ; *Ecosystem ; Fisheries ; Population Dynamics ; Reproduction ; Swimming ; Tuna/genetics/*physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 3
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    Breathing gas mixtures different from air: an adaptation for survival under the ice of a facultative air-breathing fish (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-04-15
    Description: Gaseous respiration by central mudminnows (Umbra limi), particularly their use of bubbles composed of gas mixtures other than air, may have evolved as an adaptation to the oxygen-depleted, carbon dioxide-rich water of winterkill lakes. Under simulated winterkill conditions, mudminnows frequently engulfed gaseous bubbles. Use of bubbles was not related to varying methane or nitrogen content (0 to 80 percent) when all bubbles contained 20 percent oxygen. When the oxygen content of bubbles varied (0 to 20 percent), fish visited bubbles randomly but remained longer and took fewer "breaths" at bubbles with high oxygen content. High temperature (16 degrees to 34 degrees C) and low pH (6.8 to 4.5) did not stimulate increased air-breathing when dissolved oxygen was sufficient.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Magnuson, J J -- Keller, J W -- Beckel, A L -- Gallepp, G W -- New York, N.Y. -- Science. 1983 Apr 15;220(4594):312-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17732920" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 4
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    The fishing problem: exploitation of marine communities (1986)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1986-06-13
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Magnuson, J J -- New York, N.Y. -- Science. 1986 Jun 13;232(4756):1447.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17828921" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 5
    Electronic Resource
    Electronic Resource
    Temporal coherence in the limnology of a suite of lakes in Wisconsin, U.S.A. (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 23 (1990), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. 1. Temporal coherence between pairs of lakes over 7 years was measured for thirty-seven limnological variables in seven lakes at the North Temperate Lakes Long Term Ecological Research site in Northern Wisconsin. This analysis tested. First, whether lakes more similar in exposure to the atmosphere were more temporally coherent than lakes which differed more in exposure and, second, whether temporal coherence in lakes progressively decreased from variables more directly influenced by climatic factors such as thermal and hydrologic properties, to those chemical and biological properties which may be less directly influenced by climatic factors.2. The lakes were a heterogeneous set in respect to exposure to climatic factors as estimated by the ratio of‘lake area/mean depth’and by other morphometric features, and they also differed in their position in the landscape, fertility and fish assemblages. Limnological variables formed a progression from those expected to respond directly to climatic factors to those which would not. They ranged from water level and temperatures to chemical variables such as pH, calcium concentrations and total dissolved phosphorus to biological variables such as chlorophyll concentrations, invertebrate and fish abundances.3. Coherence was estimated by the correlation between lake pairs for each of the different variables. The mean correlation and the percentage of strong correlations were calculated for each lake pair across all variables, and for each variable across all lake pairs, and both measures of coherence gave similar answers to the questions posed above.4. Temporal coherence between takes was higher for lakes similar in their exposure to climatic factors; mean correlation (r̄) being +0.3 to +0.7 for these lakes and 〈+0.3 for lakes not similar in exposure. None of the lake pairs had high coherence across all variables.5. Temporal coherence between lakes was greater for limnological variables directly influenced by climatic factors than for variables either indirectly affected by climate or complexly influenced by other types of factors. Water-level variables had a coherence near 1, r̄=0.9. All biological variables had low coherence, some near r̄=0.0. Chemical variables more likely to be influenced directly by climatic factors appeared to be more coherent than those more influenced by hydrology or biology. Most silica and phosphorus variables had coherences less than r̄=0.15.6. Coherence was not as strongly related to similarity in landscape position as it was to similarity in exposure to climatic factors, and was not jelated to the proximity of the lake pairs or to their similarity in fertility.7. A conceptual model was presented to explain how climatic signals are filtered by the lake's exposure to climatic factors and by terrestrially mediated and in-lakc processes to reduce the coherence of lake pairs owing to time lags, frequency shifts and complex interference pattems.8. Coherence is an important property to evaluate because it influences how broadly we can extrapolate results from a lake or set of lakes (for example, to a lake district) and because manipulative whole lake experiments often use adjacent lakes as reference lakes to evaluate treatment effects. The low coherence in this set of lakes in general and of individual variables such as chlorophyll concentrations and yellow perch year-class strength are discussed.9. We found no studies that explicitly addressed interlake coherence; one long-term study of forest production made it clear that coherence among sites in a landscape will be a function of scale.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1990.tb00259.x
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  • 6
    Electronic Resource
    Electronic Resource
    Stocking piscivores to improve fishing and water clarity: a synthesis of the Lake Mendota biomanipulation project (2002)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 47 (2002), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARYY 1. A total of 2.7 × 106 walleye fingerlings and 1.7 × 105 northern pike fingerlings were stocked during 1987–99 in eutrophic Lake Mendota. The objectives of the biomanipulation were to improve sport fishing and to increase piscivory to levels that would reduce planktivore biomass, increase Daphnia grazing and ultimately reduce algal densities in the lake. The combined biomass of the two piscivore species in the lake increased rapidly from 〈 1 kg ha−1 and stabilised at 4–6 kg ha−1 throughout the evaluation period.2. Restrictive harvest regulations (i.e. increase in minimum size limit and reduction in bag limit) were implemented in 1988 to protect the stocked piscivores. Further restrictions were added in 1991 and 1996 for walleye and northern pike, respectively. These restrictions were essential because fishing pressure on both species (especially walleye) increased dramatically during biomanipulation.3. Commencing in 1987 with a massive natural die-off of cisco and declining yellow perch populations, total planktivore biomass dropped from about 300–600 kg ha−1 prior to the die-off and the fish stocking, to about 20–40 kg ha−1 in subsequent years. These low planktivore biomasses lasted until a resurgence in the perch population in 1999.4. During the period prior to biomanipulation when cisco were very abundant, the dominant Daphnia species was the smaller-bodied D. galeata mendotae, which usually reached a biomass maximum in June and then crashed shortly thereafter. Beginning in 1988, the larger-bodied D. pulicaria dominated, with relatively high biomasses occurring earlier in the spring and lasting well past mid-summer of many years.5. In many years dominated by D. pulicaria, Secchi disc readings were greater during the spring and summer months when compared with years dominated by D. galeata mendotae. During the biomanipulation evaluation period, phosphorus (P) levels also changed dramatically thus complicating our analysis. Earlier research on Lake Mendota had shown that Daphnia grazing increased summer Secchi disc readings, but P concentrations linked to agricultural and urban runoff and to climate-controlled internal mixing processes were also important factors affecting summer readings.6. The Lake Mendota biomanipulation project has been a success given that high densities of the large-bodied D. pulicaria have continued to dominate for over a decade, and the diversity of fishing opportunities have improved for walleye, northern pike and, more recently, yellow perch.7. Massive stocking coupled with very restrictive fishing regulations produced moderate increases in piscivore densities. Larger increases could be realised by more drastic restrictions on sport fishing, but these regulations would be very controversial to anglers.8. If the lake's food web remains in a favourable biomanipulation state (i.e. high herbivory), further improvements in water clarity are possible with future reductions in P loadings from a recently initiated non-point pollution abatement programme in the lake's drainage basin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2002.01011.x
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  • 7
    Electronic Resource
    Electronic Resource
    A network for long-term ecological research in the United States (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 23 (1990), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. 1. A network of seventeen long-term ecological research sites funded by the National Science Foundation (NSF) and spanning sites in arctic to tropical climates, low to high altitudes and wet to dry environments, provides evidence for the increasing popularity of sustained ecological research in the U.S.A.2. The sites function as regional or national facilities for long-term research as well as for comparative and process studies by investigators from the operating institutions and by visiting researchers.3. The aquatic habitats include a variety of lakes ponds, wetlands and a playa; montane, woodland, tundra and prairie streams; as well as salt marsh, estuary, ocean beach and inshore oceanic sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1990.tb00258.x
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of changing spatial scale on acoustic observations of patchiness in the Gulf Stream (1992)
    Springer
    Landscape ecology 6 (1992), S. 279-291 
    Details
    ISSN: 1572-9761
    Keywords: patchiness ; nekton ; Gulf Stream ; acoustics ; scale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We examine the influence of spatial scale on studies of nektonic patchiness at the north edge of the Gulf Stream by altering the grain size of acoustic cross sections and applying a patch-finding algorithm. From original ‘pictures’ of 180 pixels deep by 540–1260 pixels long, we averaged depth and length, to give 9 scales ranging from fine grain (1 m vertical × 25 m horizontal sized pixels) to coarse grain (12 m × 300 m sized pixels). Measures of overall echo intensity within patches were the most predictable and showed little change with scale. Measures of variability of the echo within patches showed simple negative trends with scale and were best measured at fine spatial scales. Patch size and shape related variables have a more complex relationship with scale with differences between day and night transects more pronounced at intermediate scales. This suggests behavioral patch forming mechanisms within the nekton occur at a specific grain size (4 m vertical × 100 m horizontal) within the Gulf Stream front.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00129706
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  • 9
    Electronic Resource
    Electronic Resource
    Experimental acidification of Little Rock Lake, Wisconsin (1986)
    Springer
    Water, air & soil pollution 31 (1986), S. 115-121 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The controlled acidification of a two-basin lake is described. The lake was divided by a vinyl curtain in 1984; acidification of one basin began in 1985. Target pH values of 5.5, 5.0 and 4.5 are planned for 2-yr increments. Biotic and chemical responses and internal alkalinity generation are being studied. Baseline studies, initial results at pH 5.5, and predictions of lake responses to acidification are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00630825
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  • 10
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    Compensatory dynamics are rare in natural ecological communities (2007)
    National Academy of Sciences
    Details
    Publication Date: 2007-02-21
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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