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  • 1
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    Ice roads through lake-rich Arctic watersheds: Integrating climate uncertainty and freshwater habitat responses into adaptive management (2019)
    Taylor & Francis
    In:  EPIC3Arctic, Antarctic, and Alpine Research, Taylor & Francis, 51(1), pp. 9-23, ISSN: 1523-0430
    Details
    Publication Date: 2019-03-12
    Description: Vast mosaics of lakes, wetlands, and rivers on the Arctic Coastal Plain give the impression of water surplus. Yet long winters lock freshwater resources in ice, limiting freshwater habitats and water supply for human uses. Increasingly the petroleum industry relies on lakes to build temporary ice roads for winter oil exploration. Permitting water withdrawal for ice roads in Arctic Alaska is dependent on lake depth, ice thickness, and the fish species present. Recent winter warming suggests that more winter water will be available for ice- road construction, yet high interannual variability in ice thickness and summer precipitation complicates habitat impact assessments. To address these concerns, multidisciplinary researchers are working to understand how Arctic freshwater habitats are responding to changes in both climate and water use in northern Alaska. The dynamics of habitat availability and connectivity are being linked to how food webs support fish and waterbirds across diverse freshwater habitats. Moving toward watershed-scale habitat classification coupled with scenario analysis of climate extremes and water withdrawal is increasingly relevant to future resource management decisions in this region. Such progressive refinement in understanding responses to change provides an example of adaptive management focused on ensuring responsible resource development in the Arctic.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 2
    Electronic Resource
    Electronic Resource
    Dynamics of the exotic Daphnia lumholtzii and native macro-zooplankton in a subtropical chain-of-lakes in Florida, U.S.A. (2000)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 45 (2000), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Seasonal dynamics of the exotic Daphnia lumholtzii and native macro-zooplankton species were studied for 2 years in six inter-connected lakes in Florida, U.S.A. The lakes ranged widely in pH, colour and trophic status, and were dominated by copepods. 
2. All six lakes contained both D. lumholtzii and the native D. ambigua, but the two species did not overlap in time. D. ambigua was dominant in autumn–spring, coinciding with lower water temperature, higher transparency and lower nutrient and chlorophyll a (Chl a) concentrations than in summer, when D. lumholtzii was dominant. 
3. Based on the field observations, temperature optima were 24 °C for D. ambigua and 29 °C for D. lumholtzii, suggesting that temperature plays a role in determining dominance among the daphnids of subtropical Florida lakes. 
4. D. lumholtzii has not displaced native cladocerans but occupies a ‘vacant’ seasonal niche, unexploited due to the inability of native taxa to tolerate high temperature. Furthermore, D. lumholtzii did not significantly alter algal–zooplankton interactions. There was evidence of top–down control by grazing, but it was primarily attributable to the native taxa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2000.00614.x
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  • 3
    Electronic Resource
    Electronic Resource
    Distribution of planktonic ciliates in highly coloured subtropical lakes: comparison with clearwater ciliate communities and the contribution of myxotrophic taxa to total autotrophic biomass (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 20 (1988), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY 1. The planktonic ciliate communities of eleven organically coloured north and central Florida lakes representing a variety of trophic conditions were examined during 1979–80. The total abundance and biomass of ciliates were not significantly different from comparable clearwater lakes and only minor taxonomic replacements were noted at the order level.2. Timing of population peaks of oligotrophic lakes was dissimilar to clearwater lakes of the same trophic state, but seasonality in meso-trophic and eutrophic lakes resembled patterns described for comparable clearwater lakes.3. Various ciliate components were strongly correlated with chlorophyll a concentrations, but only moderately correlated to dominant phytoplankton groups. No significant correlations were found between ciliate components and bacterial abundance.4. Myxotrophic taxa numerically dominated oligotrophic systems, particularly during midsummer, and accounted for a large percentage of the total ciliate biomass. Estimates of the ciliate contribution to total autotrophic biomass indicate that these zoochlorellae-bearing protozoa may account for much of the autotrophic biomass during midsummer periods in coloured lakes, and thus may lead to an overestimation of phytoplankton standing crops available to zooplankton grazers if chlorophyll a is used as a surrogate measure of algal biomass.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1988.tb01716.x
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  • 4
    Electronic Resource
    Electronic Resource
    The role of ciliated protozoa in pelagic freshwater ecosystems (1989)
    Springer
    Microbial ecology 17 (1989), S. 111-136 
    Details
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The abundance and biomass of ciliates are both strongly related to lake trophic status as measured by chlorophylla concentrations. Taxonomic replacements occur with increasing eutrophication such that large-bodied forms (predominantly oligotrichs) are progressively replaced by smaller-bodied ciliates (mainly scuticociliates). Highly acidic lakes display a more pronounced dominance of large-bodied forms when contrasted with less acidic lakes of comparable trophy. Community structure of ciliate populations is determined largely by lake trophy with acidic oligotrophic systems being characterized by reduced diversity and species richness compared with hypereutrophic systems. The temporal and spatial distribution of small (〈 100μm) ciliate populations is ascribed to lake thermal regimes which provide localized concentrations of food resources. Likewise, in extremely productive lakes, very large (〉 100μm) meroplanktonic ciliates enter the water column during midsummer after the development of thermal stratification and associated profundal deoxygenation. Laboratory studies indicate that large zooplankton (crustaceans) are capable of utilizing ciliates as a food source, but there is little direct evidence from field studies documenting this trophic link. Ciliates can be voracious grazers of both bacterioplankton and phytoplankton, and each species has a distinct range of preferred particle size which is a function of both mouth size and morphology. Myxotrophic ciliates may be important components in some plankton communities, particularly during periods of nutrient limitation or after their displacement from the benthos of eutrophic lakes. Evidence regarding the importance of planktonic ciliated protozoa in nutrient regeneration and as intermediaries in energy flow is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02011847
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  • 5
    Electronic Resource
    Electronic Resource
    Midsummer zooplankton assemblages in four types of wetlands in the Upper Midwest, USA (1998)
    Springer
    Hydrobiologia 380 (1998), S. 209-220 
    Details
    ISSN: 1573-5117
    Keywords: wetlands ; zooplankton ; phytoplankton ; Ohio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The objective of this study was to characterize the zooplankton and phytoplankton assemblages of four different types of wetlands and to evaluate their use as environmental indicators. Total abundances, community composition, and species diversity were evaluated for zooplankton and phytoplankton assemblages from 24 wetlands and related to water quality variables. During August 1995, six representative sites were sampled from four types of wetlands designated as constructed, impacted, non-impacted, or temporary. The plankton assemblages of all wetlands were dominated by cosmopolitan crustacean, rotifer, and phytoplankton taxa typical of lake plankton communities. Species diversity, richness, and evenness of zooplankton and phytoplankton assemblages did not differ significantly among the wetland types. Total zooplankton abundance was significantly (p 〈 0.01) related to chlorophyll a and total phosphorus concentrations over the range of trophic conditions. Mean zooplankton densities and phytoplankton biovolumes were similar among the wetlands, however, the relative abundances of major zooplankton groups differed among the wetland types. Cyanophytes, primarily Oscillatoria spp., were a major component of the phytoplankton across all four wetland types, and were significantly more abundant within the constructed and temporary sites. On average, rotifers accounted for 79% of total zooplankton abundance within the constructed wetlands and were much less dominant in the non-impacted and temporary wetlands. Cladoceran, copepodite, and adult copepod concentrations were low in the constructed and impacted wetlands and increased in the non-impacted and temporary wetlands in conjunction with increased chlorophytes and cryptophytes. Our preliminary survey suggests that abiotic factors which are known to directly affect phytoplankton may indirectly affect zooplankton composition in such a way as to use zooplankton assemblages as indicators of water quality. However, further study incorporating seasonal dynamics and the influence of predators on zooplankton assemblages is needed to fully assess the use of zooplankton community composition as an environmental indicator for wetland systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003452118351
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  • 6
    Electronic Resource
    Electronic Resource
    Thermal regimes of Florida lakes (1981)
    Springer
    Hydrobiologia 83 (1981), S. 267-273 
    Details
    ISSN: 1573-5117
    Keywords: thermal ; regimes ; subtropical lakes ; Florida
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Water column temperatures were determined monthly for 24 lakes and bimonthly for 5 lakes in peninsular Florida during 1979. Three geographical groups (north, central, south) were delineated from mean monthly water column temperatures for individual lakes. On a monthly basis, northern lakes were least similar to southern lakes, while central Florida lakes displayed greater affinity to the southern than to the northern lake group. Temperature differences between lake groups broke down during late summer. Subtropical lakes have been defined tentatively as those Florida lakes south of 28° latitude which possess warm monomictic circulation and a mean annual temperature of 24.2 ± 4.8 °C with minimum water column temperature rarely less than 14 °C and summer maxima rarely exceeding 31 °C. While all lakes in Florida are clearly warm monomictic annual nutrient cycling and productivity patterns may be influenced by inter-group differences in the timing and duration of water column circulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00008277
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  • 7
    Electronic Resource
    Electronic Resource
    Temporal variability in algal biomass and primary productivity in Florida lakes relative to latitudinal gradients, organic color and trophic state (1991)
    Springer
    Hydrobiologia 224 (1991), S. 89-97 
    Details
    ISSN: 1573-5117
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seasonal patterns in primary productivity and algal biomass in subtropical Florida lakes along increasing gradients of both dissolved organic color and phytoplankton biomass are presented. Chlorophyll a concentrations and gross primary productivity generally reached maxima during the summer and were most depressed in winter months, regardless of color or trophic classification. Primary productivity was more strongly correlated with chlorophyll a, nutrient concentrations and water clarity in clearwater (〈 75 Pt units) than in colored (〉 75 Pt units) systems. Amplitudes in algal biomass were considerably smaller than temperate lakes. Variability in primary production in Florida lakes was intermediate to patterns in the temperate zone and tropics, but was more closely aligned to northern latitudes. Within the Florida peninsula, variability of primary productivity decreased from north to south and corresponded to latitudinal gradients in climatic regimes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00006865
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Analysis of the community structure of planktonic ciliated protozoa relative to trophic state in Florida lakes (1989)
    Springer
    Hydrobiologia 174 (1989), S. 177-184 
    Details
    ISSN: 1573-5117
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The planktonic ciliate populations of 30 Florida lakes constituting a broad trophic gradient were examined to determine the response of protozoan community structure to increasing eutrophication. Both ciliate abundance and biomass were strongly related to lake trophic state. Comparison of the Florida data base with a comparable north temperate lake group indicated that subtropical lakes generally possess higher ciliate abundance and biomass at a given trophic state than temperate lakes. However the equations derived for each data base were not significantly different. Community diversity and species richness increased with increasing lake productivity. Highly acidic lakes displayed significantly reduced diversity and numbers of species when contrasted with nonacidic oligotrophic lakes. Small-bodied (〈 30 um) ciliates dominated all lakes but were proportionally less important in oligotrophic lakes. Presence-absence data produced three assemblages: an ubiquitous association of primarily small ciliate taxa, a group of large ciliates mainly restricted to eutrophic-hypereutrophic lakes, and a very large ciliate,Stentor niger, which dominated the protozoan communities of acidic oligotrophic lakes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00008155
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  • 9
    Electronic Resource
    Electronic Resource
    Seasonality of planktonic ciliated protozoa in 20 subtropical Florida lakes of varying trophic state (1990)
    Springer
    Hydrobiologia 190 (1990), S. 127-135 
    Details
    ISSN: 1573-5117
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The planktonic ciliate populations of 20 Florida lakes ranging from oligotrophic to hypereutrophic were examined monthly for one year. Oligotrophic lakes displayed abundance peaks during fall mixis and biomass peaks in late winter and fall. Mesotrophic systems exhibited a spring-fall bimodality in ciliate abundance with a biomass maxima occurring during fall. Eutrophic/hypereutrophic lakes had pronounced abundance and biomass maxima during summer, with the large ciliates Plagiopyla nasuta and Paramecium trichium often contributing heavily to the midsummer biomass peak. Members of the Oligotrichida numerically dominated abundance and biomass peaks in oligotrophic lakes while the Scuticociliatida dominated the communities of higher trophic states. Total ciliate abundance and biomass were strongly correlated with chlorophyll a concentrations as were various ciliate taxonomic groups. The relationship between ciliate seasonal distribution in these subtropical lakes with lake thermal regimes and trophic state is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00014103
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