@article{PerillonvandeWeyerPaezoltetal.2018,
  author    = {Perillon, Cecile and van de Weyer, Klaus and P{\"a}zolt, Jens and Kasprzak, Peter and Hilt, Sabine},
  title     = {Changes in submerged macrophyte colonization in shallow areas of an oligo-mesotrophic lake and the potential role of groundwater},
  series = {Limnologica : ecology and management of inland waters},
  volume    = {68},
  journal   = {Limnologica : ecology and management of inland waters},
  publisher = {Elsevier},
  address   = {Jena},
  issn      = {0075-9511},
  doi       = {10.1016/j.limno.2017.03.002},
  pages     = {168 -- 176},
  year      = {2018},
  abstract  = {Groundwater influx can significantly contribute to nutrient budgets of lakes and its influence is strongest in shallow littoral areas. In oligo-or mesotrophic systems, additional nutrient supply by groundwater influx may affect benthic primary producers and their interactions. Potential changes can be expected in community composition, biomass, stoichiometry and interactions between submerged macrophytes and epiphyton.},
  language  = {en}
}
@article{HuLudsinMartinetal.2018,
  author    = {Hu, Chenlin and Ludsin, Stuart A. and Martin, Jay F. and Dittmann, Elke and Lee, Jiyoung},
  title     = {Mycosporine-like amino acids (MAAs)-producing Microcystis in Lake Erie},
  series = {Harmful algae},
  volume    = {77},
  journal   = {Harmful algae},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1568-9883},
  doi       = {10.1016/j.hal.2018.05.010},
  pages     = {1 -- 10},
  year      = {2018},
  abstract  = {Mycosporine-like amino acids (MAAs) are UV-absorbing metabolites found in cyanobacteria. While their protective role from UV in Microcystis has been studied in a laboratory setting, a full understanding of the ecology of MAA-producing versus non-MAA-producing Microcystis in natural environments is lacking. This study presents a new tool for quantifying MAA-producing Microcystis and applies it to obtain insight into the dynamics of MAA-producing and non-MAA-producing Microcystis in Lake Erie. This study first developed a sensitive, specific TaqMan real-time PCR assay that targets MAA synthetase gene C (mysC) of Microcystis (quantitative range: 1.7 × 101 to 1.7 × 107 copies/assay). Using this assay, Microcystis was quantified with a MAA-producing genotype (mysC+) in water samples (n = 96) collected during March-November 2013 from 21 Lake Erie sites (undetectable - 8.4 × 106 copies/ml). The mysC+ genotype comprised 0.3-37.8\% of the Microcystis population in Lake Erie during the study period. The proportion of the mysC+ genotype during high solar UV irradiation periods (mean = 18.8\%) was significantly higher than that during lower UV periods (mean = 9.7\%). Among the MAAs, shinorine (major) and porphyra (minor) were detected with HPLC-PDA-MS/MS from the Microcystis isolates and water samples. However, no significant difference in the MAA concentrations existed between higher and lower solar UV periods when the MAA concentrations were normalized with Microcystis mysC abundance. Collectively, this study's findings suggest that the MAA-producing Microcystis are present in Lake Erie, and they may be ecologically advantageous under high UV conditions, but not to the point that they exclusively predominate over the non-MAA-producers.},
  language  = {en}
}
@article{TangFluryGrossartetal.2017,
  author    = {Tang, Kam W. and Flury, Sabine and Grossart, Hans-Peter and McGinnis, Daniel F.},
  title     = {The Chaoborus pump: Migrating phantom midge larvae sustain hypolimnetic oxygen deficiency and nutrient internal loading in lakes},
  series = {Water research},
  volume    = {122},
  journal   = {Water research},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0043-1354},
  doi       = {10.1016/j.watres.2017.05.058},
  pages     = {36 -- 41},
  year      = {2017},
  abstract  = {Hypolimnetic oxygen demand in lakes is often assumed to be driven mainly by sediment microbial processes, while the role of Chaoborus larvae, which are prevalent in eutrophic lakes with hypoxic to anoxic bottoms, has been overlooked. We experimentally measured the respiration rates of C flavicans at different temperatures yielding a Q(10) of 1.44-1.71 and a respiratory quotient of 0.84-0.98. Applying the experimental data in a system analytical approach, we showed that migrating Chaoborus larvae can significantly add to the water column and sediment oxygen demand, and contribute to the observed linear relationship between water column respiration and depth. The estimated phosphorus excretion by Chaoborus in sediment is comparable in magnitude to the required phosphorus loading for eutrophication. Migrating Chaoborus larvae thereby essentially trap nutrients between the water column and the sediment, and this continuous internal loading of nutrients would delay lake remediation even when external inputs are stopped. (C) 2017 Elsevier Ltd. All rights reserved.},
  language  = {en}
}
@article{ReineckeKlemmHeinken2014,
  author    = {Reinecke, Jennifer and Klemm, Gunther and Heinken, Thilo},
  title     = {Vegetation change and homogenization of species composition in temperate nutrient deficient scots pine forests after 45 yr},
  series = {Journal of vegetation science},
  volume    = {25},
  journal   = {Journal of vegetation science},
  number    = {1},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {1100-9233},
  doi       = {10.1111/jvs.12069},
  pages     = {113 -- 121},
  year      = {2014},
  abstract  = {QuestionDoes eutrophication drive vegetation change in pine forests on nutrient deficient sites and thus lead to the homogenization of understorey species composition? LocationForest area (1600ha) in the Lower Spreewald, Brandenburg, Germany. MethodsResurvey of 77 semi-permanent plots after 45yr, including vascular plants, bryophytes and ground lichens. We applied multidimensional ordination of species composition, dissimilarity indices, mean Ellenberg indicator values and the concept of winner/loser species to identify vegetation change between years. Differential responses along a gradient of nutrient availability were analysed on the basis of initial vegetation type, reflecting topsoil N availability of plots. ResultsSpecies composition changed strongly and overall shifted towards higher N and slightly lower light availability. Differences in vegetation change were related to initial vegetation type, with strongest compositional changes in the oligotrophic forest type, but strongest increase of nitrophilous species in the mesotrophic forest type. Despite an overall increase in species number, species composition was homogenized between study years due to the loss of species (mainly ground lichens) on the most oligotrophic sites. ConclusionsThe response to N enrichment is confounded by canopy closure on the N-richest sites and probably by water limitation on N-poorest sites. The relative importance of atmospheric N deposition in the eutrophication effect is difficult to disentangle from natural humus accumulation after historical litter raking. However, the profound differences in species composition between study years across all forest types suggest that atmospheric N deposition contributes to the eutrophication, which drives understorey vegetation change and biotic homogenization in Central European Scots pine forests on nutrient deficient sites.},
  language  = {en}
}
@article{StoofLeichsenringJungingerOlakaetal.2011,
  author    = {Stoof-Leichsenring, Kathleen Rosemarie and Junginger, Annett and Olaka, Lydia A. and Tiedemann, Ralph and Trauth, Martin H.},
  title     = {Environmental variability in Lake Naivasha, Kenya, over the last two centuries},
  series = {Journal of paleolimnolog},
  volume    = {45},
  journal   = {Journal of paleolimnolog},
  number    = {3},
  publisher = {Springer},
  address   = {Dordrecht},
  issn      = {0921-2728},
  doi       = {10.1007/s10933-011-9502-4},
  pages     = {353 -- 367},
  year      = {2011},
  abstract  = {Lake Naivasha, Kenya, is one of a number of freshwater lakes in the East African Rift System. Since the beginning of the twentieth century, it has experienced greater anthropogenic influence as a result of increasingly intensive farming of coffee, tea, flowers, and other horticultural crops within its catchment. The water-level history of Lake Naivasha over the past 200 years was derived from a combination of instrumental records and sediment data. In this study, we analysed diatoms in a lake sediment core to infer past lacustrine conductivity and total phosphorus concentrations. We also measured total nitrogen and carbon concentrations in the sediments. Core chronology was established by (210)Pb dating and covered a similar to 186-year history of natural (climatic) and human-induced environmental changes. Three stratigraphic zones in the core were identified using diatom assemblages. There was a change from littoral/epiphytic diatoms such as Gomphonema gracile and Cymbella muelleri, which occurred during a prolonged dry period from ca. 1820 to 1896 AD, through a transition period, to the present planktonic Aulacoseira sp. that favors nutrient-rich waters. This marked change in the diatom assemblage was caused by climate change, and later a strong anthropogenic overprint on the lake system. Increases in sediment accumulation rates since 1928, from 0.01 to 0.08 g cm(-2) year(-1) correlate with an increase in diatom-inferred total phosphorus concentrations since the beginning of the twentieth century. The increase in phosphorus accumulation suggests increasing eutrophication of freshwater Lake Naivasha. This study identified two major periods in the lake's history: (1) the period from 1820 to 1950 AD, during which the lake was affected mainly by natural climate variations, and (2) the period since 1950, during which the effects of anthropogenic activity overprinted those of natural climate variation.},
  language  = {en}
}
@article{LauterbachRoemermannJeltschetal.2013,
  author    = {Lauterbach, D. and Roemermann, C. and Jeltsch, Florian and Ristow, Michael},
  title     = {Factors driving plant rarity in dry grasslands on different spatial scales: a functional trait approach},
  series = {BIODIVERSITY AND CONSERVATION},
  volume    = {22},
  journal   = {BIODIVERSITY AND CONSERVATION},
  number    = {10},
  publisher = {SPRINGER},
  address   = {DORDRECHT},
  issn      = {0960-3115},
  doi       = {10.1007/s10531-013-0455-y},
  pages     = {2337 -- 2352},
  year      = {2013},
  abstract  = {In European dry grasslands land-use changes affect plant species performance and frequency. Potential driving forces are eutrophication and habitat fragmentation. The importance of these factors is presumably scale dependent. We used a functional trait approach to detect processes that influence species frequency and endangerment on different spatial scales. We tested for associations between functional traits and (1) frequency and (2) degree of endangerment on local, regional and national scales. We focussed on five selected traits that describe the life-history of plant species and that are related to competition, dispersal ability and habitat specificity. Trait data on plant height, SLA, plant coverage, peak of flowering and diaspore mass were measured for 28 perennials from common to rare and endangered to non-endangered on 59 dry grassland sites in north-eastern Germany. Multiple regression models revealed that species frequency is positively and species endangerment negatively related to plant height, plant coverage and SLA on more than one spatial scale. On the local scale, diaspore mass has a negative effect on species frequency. More frequent and less endangered species show a later peak of flowering on nationwide and regional scales. We concluded that competition traits are more important on larger scales, whereas dispersal traits are more important for species frequency on the smaller scale. On national and regional scales, eutrophication and habitat loss may be the main drivers of species threat, whereas on the local scale fragmentation plays a crucial role for the performance of dry grassland species.},
  language  = {en}
}
@article{HundBrownLavkulichetal.2013,
  author    = {Hund, Silja V. and Brown, Sandra and Lavkulich, Les M. and Oswald, Sascha Eric},
  title     = {Relating P Lability in Stream Sediments to Watershed Land Use via an Effective Sequential Extraction Scheme},
  series = {Water, air \& soil pollution : an international journal of environmental pollution},
  volume    = {224},
  journal   = {Water, air \& soil pollution : an international journal of environmental pollution},
  number    = {9},
  publisher = {Springer},
  address   = {Dordrecht},
  issn      = {0049-6979},
  doi       = {10.1007/s11270-013-1643-9},
  pages     = {13},
  year      = {2013},
  abstract  = {High applications of P fertilizers and manure are general practice in intensive agriculture and may cause eutrophication in adjacent streams. Bioavailability of P can be estimated by sequential extractions commonly used for soil or sediment. A single combined method may facilitate more effective comparisons of topsoils and adjoining stream sediments, and enhance management decisions. In this study, the suitability of an established soil P sequential extraction was tested on stream bed sediments. The study was conducted in the Sumas River watershed in the agricultural Lower Fraser Valley, Canada. Sediment samples with differing land use (forest, low and high intensity agriculture) from 1993, 1994, 2008, and 2009 from 14 sites along the Sumas River and tributaries were used. Total sequential extraction concentrations were in agreement with aqua regia digestion (Rs=0.96) and showed consistency over the study time sequence. P fractions released by 0.5 M NaHCO3 (median 14 \%), 0.1 M NaOH (33 \%), and 1.0 M HCl (38 \%) were significantly (alpha=0.05) higher than P released by other extractants. These three extraction steps provide a practical and time-effective assessment of P lability in stream sediments and may be used as a combined scheme for sediment and soil. Analytical results further revealed that land use has a major and characteristic impact on P lability. With a land use change from forest to intensive agriculture, results showed an increase in total P concentrations (30 to 4,000 ppm) and in P lability, in particular for the moderately labile NaOH-P fraction (20 to 50 \%).},
  language  = {en}
}