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Benson B.J.,University of Wisconsin - Madison | Magnuson J.J.,University of Wisconsin - Madison | Jensen O.P.,Rutgers University | Card V.M.,Metropolitan State University | And 7 more authors.
Climatic Change | Year: 2012

Often extreme events, more than changes in mean conditions, have the greatest impact on the environment and human well-being. Here we examine changes in the occurrence of extremes in the timing of the annual formation and disappearance of lake ice in the Northern Hemisphere. Both changes in the mean condition and in variability around the mean condition can alter the probability of extreme events. Using long-term ice phenology data covering two periods 1855-6 to 2004-5 and 1905-6 to 2004-5 for a total of 75 lakes, we examined patterns in long-term trends and variability in the context of understanding the occurrence of extreme events. We also examined patterns in trends for a 30-year subset (1975-6 to 2004-5) of the 100-year data set. Trends for ice variables in the recent 30-year period were steeper than those in the 100- and 150-year periods, and trends in the 150-year period were steeper than in the 100-year period. Ranges of rates of change (days per decade) among time periods based on linear regression were 0. 3-1. 6 later for freeze, 0. 5-1. 9 earlier for breakup, and 0. 7-4. 3 shorter for duration. Mostly, standard deviation did not change, or it decreased in the 150-year and 100-year periods. During the recent 50-year period, standard deviation calculated in 10-year windows increased for all ice measures. For the 150-year and 100-year periods changes in the mean ice dates rather than changes in variability most strongly influenced the significant increases in the frequency of extreme lake ice events associated with warmer conditions and decreases in the frequency of extreme events associated with cooler conditions. © 2011 Springer Science+Business Media B.V.


News Article | February 15, 2017
Site: www.eurekalert.org

"It had remained unclear whether or not the accumulation of alien species has already reached a point of slow-down", says Dr Hanno Seebens from the Senckenberg Biodiversity and Climate Research Centre (BiK-F) in Frankfurt, Germany. The first author of the study has an answer now: "For all groups of organisms on all continents, the number of alien species has increased continuously during the last 200 years. For most groups, even the rate of introduction is highest recently. Barring mammals and fishes, there are no signs of a slow-down and we have to expect more new invasions in the near future." Mark van Kleunen, professor of ecology at the University of Konstanz and one of the co-authors of the study, expects that the number of alien species will increase further in the near future - "as a consequence of climate change, which makes it possible for many alien plants in our gardens to jump the fence and settle in the wild". In the joint research project the researchers established a database of the date an alien species was first detected in a region outside the species' native range. Using more than 45.000 of these first records of more than 16.000 alien species, they analysed the development of alien species accumulation during the last centuries. The researchers found that 37% of all recorded alien species have been introduced in the last few decades between 1970-2014. At its peak, 585 new species were recorded within one year. This corresponds to more than 1.5 new alien species per day globally. "As the date of first record is not available for most alien species, these numbers are clearly underestimating the full extent of alien species introductions", says Dr. Franz Essl from the University of Vienna, Austria, senior author of the study. The trends of increase vary among taxonomic groups, which can be attributed to human activities. "We observe a distinct increase in first record rates of vascular plants in the 19th century, probably as a result of the intensification of horticulture. The rates of new introductions of other organisms such as algae, molluscs or insects increased steeply after 1950. This is most likely a consequence of the ongoing globalisation of trade," explains Seebens, who earned his doctorate at the Limnological Institute of the University of Konstanz in 2008. The unprecedented increase in alien species numbers can have extremely negative impacts on native ecosystems, as native plants might be eliminated and entire ecosystems change. Floras and faunas worldwide assimilate more and more, resulting in a loss of regional variety. Therefore various legislations are currently in force globally attempting to mitigate the introduction of new alien species. "However, our results show that the past efforts have not been effective enough to keep up with ongoing globalisation. There is an urgent need to implement more effective prevention policies at all scales", concludes Essl. Seebens et al.: No saturation in the accumulation of alien species worldwide. Nature Communications 8:14435 | DOI: 10.1038/ncomms14435 You can download photos here: https:/ Caption: The eastern grey squirrel, originally from North America, was introduced to various locations worldwide, including the UK, where it has largely displaced the native red squirrel. Photo: Tim M. Blackburn, University College London https:/ Caption: The rose-ringed parakeet is native to parts of Africa and Asia. It was introduced as an ornamental species and has established populations at various sites in Europe, North America and Australia. Photo: Tim M. Blackburn, University College London https:/ Caption: A large population of American pokeweed (Phytolacca americana) in Hungary. This toxic plant is native to North America and was grown for ornamental and medicinal purpose in Europe. Photo: Petr Pyšek, The Czech Academy of Sciences https:/ Caption: The many-leaved lupine (Lupinus polyphyllus) is extensively used in mountain hay meadows in the The Katzbach Mountains in Poland. In Europe, this species has been planted as a fodder crop and as an ornamental, and is now widely naturalized. Photo: Barbara Tokarska-Guzik, University of Silesia in Katowice, Poland, 2016.


Kaygorodova I.A.,Limnological Institute | Mandzyak N.,Limnological Institute | Petryaeva E.,Irkutsk State University | Pronin N.M.,Institute of General and Experimental Biology
Scientific World Journal | Year: 2014

The study of leeches from Lake Gusinoe and its adjacent area offered us the possibility to determine species diversity. As a result, an updated species list of the Gusinoe Hirudinea fauna (Annelida, Clitellata) has been compiled. There are two orders and three families of leeches in the Gusinoe area: order Rhynchobdellida (families Glossiphoniidae and Piscicolidae) and order Arhynchobdellida (family Erpobdellidae). In total, 6 leech species belonging to 6 genera have been identified. Of these, 3 taxa belonging to the family Glossiphoniidae (Alboglossiphonia heteroclita f. papillosa, Hemiclepsis marginata, and Helobdella stagnalis) and representatives of 3 unidentified species (Glossiphonia sp., Piscicola sp., and Erpobdella sp.) have been recorded. The checklist gives a contemporary overview of the species composition of leeches and information on their hosts or substrates. The validity of morphological identification of each taxon has been verified by phylogenetic approach with a molecular marker adopted for a DNA barcoding of most invertebrates. © 2014 Irina A. Kaygorodova et al.


Kaygorodova I.A.,Limnological Institute | Natyaganova A.V.,Limnological Institute
Archives of Biological Sciences | Year: 2015

In this paper, we present for the first time data on karyotype analysis of leeches of the genus Baicalobdella (Piscicolidae) parasitizing Lake Baikal endemic cottoid fishes. Both mitotic and meiotic chromosomes are described. Leech testisacs were processed by a "shaking-blotting" technique, and chromosomal preparations were stained with water-based fuchsine. Diploid and haploid chromosome sets demonstrated 2n=34 and n=17, respectively, with maximal chromosome length of 1.5-3.0 μm. Comparative karyotype analysis of two ecological forms of Baicalobdella leeches revealed differences in chromosome numbers and its morphology. Previously studied Baicalobdella torquata (Grube, 1871) parasitizing Baikal amphipods had smaller diploid and haploid sets (2n=32, n=16). In addition to numerical superiority, differing patterns of chromosome size gradation and presence of satellite elements were found in the karyotype of piscine Baicalobdella leeches. This confirms the systematic position of the Baikal cottoid leech parasite as a separate species, validating the original name Baicalobdella cottidarum sensu Dogiel, 1957.


Kaygorodova I.A.,Limnological Institute | Sorokovikova N.V.,Limnological Institute
Parasitology International | Year: 2014

Sculpin fish bdellosis in Lake Baikal is caused by leech ectoparasites, which are identified as belonging to the genus Baicalobdella. In addition to Cottocomephorus grewinkii, eight sculpin hosts for Baicalobdella are newly recorded: Paracottus knerii (Cottocomephorinae), and Abyssocottus korotneffi, Asprocottus platycephalus, Batrachocottus baicalensis, Batrachocottus multiradiatus, Cyphocottus megalops, Limnocottus griseus and Procottus major (Abyssocottinae). These host fishes are mass infected by Baicalobdella leeches (up to 75%) in different sites of Lake Baikal. Comparative morphological analysis of Baicalobdella infecting sculpin fishes vs. Baicalobdella torquata proper revealed nine distinctive features that allow confirming a separate systematic position and revalidating original name Baicalobdella cottidarum Dogiel, 1957. © 2014 Elsevier Ireland Ltd.


PubMed | Limnological Institute
Type: Journal Article | Journal: Parasitology international | Year: 2014

Sculpin fish bdellosis in Lake Baikal is caused by leech ectoparasites, which are identified as belonging to the genus Baicalobdella. In addition to Cottocomephorus grewinkii, eight sculpin hosts for Baicalobdella are newly recorded: Paracottus knerii (Cottocomephorinae), and Abyssocottus korotneffi, Asprocottus platycephalus, Batrachocottus baicalensis, Batrachocottus multiradiatus, Cyphocottus megalops, Limnocottus griseus and Procottus major (Abyssocottinae). These host fishes are mass infected by Baicalobdella leeches (up to 75%) in different sites of Lake Baikal. Comparative morphological analysis of Baicalobdella infecting sculpin fishes vs. Baicalobdella torquata proper revealed nine distinctive features that allow confirming a separate systematic position and revalidating original name Baicalobdella cottidarum Dogiel, 1957.


PubMed | Limnological Institute
Type: Journal Article | Journal: Microbial ecology | Year: 2013

Three psychrotrophic and one mesophilic strains were isolated from winter water samples of different freshwater biotopes and identified asCytophaga johnsonae (C-21),Cytophaga sp. (M-17),Pseudomonas fluorescens (KD), andEnterobacter cloacae (BS-2). Temperature shift-up experiments with emphasis on low temperatures were carried out with aerated pure batch cultures in glucose mineral medium. The effects of sudden temperature increases on growth rates and substrate conversion were investigated. All three psychrotrophic strains in the temperature increase experiments at low temperatures showed differing reactions within the linear zone of the Arrhenius plot. TheC. johnsonae (C-21) shift-up cultures adjusted the growth rate immediately to the rate of the temperature adapted cultures, whereasCytophaga sp. (M-17) shift-up cultures showed a lower andP. fluorescens (KD) a higher growth rate. The mesophilicE. cloacae (BS-2), likeC. johnsonae (C-21), adjusted immediately to the new growth rate. Substrate conversion increased in all experiments immediately after the shift-up. The extracellular substrate conversion byP. fluorescens (KD) of glucose to gluconate and 2-ketogluconate was particularly affected by the sudden temperature increase.


PubMed | Limnological Institute
Type: Journal Article | Journal: Environmental monitoring and assessment | Year: 2013

This study deals with the use of the dynamics of dissolved oxygen concentration for water quality assessment in polder ditches. The dynamics of the dissolved oxygen concentration, i.e. the temporal and spatial variations in a few polder ditches under a range of natural, pollution and management conditions is presented.Five requisites formulated for the water quality indicator are discussed: (1) its relation with water quality goals, (2) nature and amount of information it provides, (3) if it could be standardized, (4) if it could be manipulated and (5) its measurability.


PubMed | Limnological Institute
Type: Journal Article | Journal: Environmental monitoring and assessment | Year: 2013

The existing data on the species composition of zooplankton and grazing intensities of crustacean plankton are discussed in the light of trophic status, particularly in the Dutch lakes of varying trophy. Several species of rotifers in northern Europe and North America are considered to indicate eutrophic environments. However, unanimity is less regarding crustacean zooplankton, since several species are encountered in lakes varying widely in trophic degree.The zooplankton to seston (33 m) biomass ratio may provide information about the ecological transfer efficiency and trophic status. In the Dutch lakes the ratio decreases sharply with increase in food concentration during eutrophication, namely from ca 0.4 in oligotrophic lakes to about 0.05 in the hypertrophic ones.The zooplankton community grazing is high and variable in lakes of low trophy but low and relatively constant in lakes of high trophy. The fluctuations in the filtering rates of Daphnia sp. (e.g. D. magna) may provide information both on trophic degree as well as dissolved substances in lake waters. The dominance of small cladocerans in lakes may be due to quality of food and trophic level, besides fish predation. The recurrent clear-water phase in lakes would indicate oligo-mesotrophic situations in which the zooplankton plays an important role in the phytoplankton wax and wane.


News Article | December 7, 2015
Site: motherboard.vice.com

On the main drag of Khuzhir, the principal town of Olkhon Island in Lake Baikal, Siberia, the dust blown from buses delivering tourists billows through the windswept streets. By the upturned chassis of vehicles picked clean of parts, babushkas wade through piles of trash, searching for anything worth claiming. In the shadows of a former prison, sunbathers line a beach around clumps of algae and rusted metal detritus. While Buryat shamans, who revere the lake as holy, perform ceremonies around totem poles festooned with ribbons on a bluff above town, in a ship graveyard below them, children toss empty vodka bottles at each other for entertainment. Stretching for 395 miles, thirty-million-year-old Baikal is the world’s deepest lake, its volume roughly equivalent to the five Great Lakes of North America combined. A UNESCO World Heritage Site, Baikal contains one-fifth of the unfrozen freshwater on the planet. Its unique closed ecosystem is home to over 3,500 species and subspecies of animals and plants, roughly sixty percent of which are not to be found anywhere else on Earth. The lake is now subject to an unprecedented catalogue of threats. I visited the region this summer, when wildfires the likes of which had never been seen before were raging, leading locals to describe the scene as feeling “like doomsday.” The lake faces a range of environmental issues: phosphate run-off from unplanned tourist developments and poor sewage treatment, the rampant growth of algae mats and a sponge die-off, and low inflow that saw water levels hit critical marks this year, down 40cm since 2013. A waterfront industrial plant that produced cellulose fiber for Soviet aircraft tyres is now closed, but dotted around the dimly-lit derelicts lie 13 toxic reservoirs, each the size of two football fields. Now, Baikal is further endangered by Mongolian plans for hydropower plants which, Professor Marianne Moore from Wellesley College told Motherboard, could potentially starve the deep waters of the lake of oxygen. Detritus on the beach near the tourist town of Khuzhir. Image: Stephen M. Bland A few miles from Khuzhir, beyond an abandoned fish factory that had operated as a gulag, I came across the rotting corpses of Nerpa seals which had washed to shore. According to Greenpeace, the number of these unique seals, one of only three entirely freshwater seal species, has decreased by approximately a third since the beginning of the 1990s. Commenting on this “huge die-off,” Greenpeace Russia campaigner Roman Vazhenkov noted that although the seals had died of disease, chlorine substance found in the creatures' fatty tissues suggests their immune systems had been weakened. I spoke to Professor Oleg Timoshkin from the Limnological Institute of the Russian Academy of Sciences about the levels of pollution threatening the lake. “In some areas of Northern Baikal, a crust of rotten spirogyra algae up to ten meters [wide] covers the once cozy beaches,” he told me. “Even cows and horses refuse to drink the water.” Emissions from a failed sewage treatment plant in the town of Severobaikalsk on the northern shore have caused a bank of foul-smelling algae to form that stretches for six miles. In addition to this, locals report that for years, sewage trucks pulled up daily to dispose of wastewater at another dilapidated station near the shoreline. “The [new] plant failed in large part because the railroad industry dumped a bunch of cleaning products into the sewage treatment facility,” Moore told Motherboard. “They were cleaning railroad cars with heavy duty detergent and it killed the microbes that helped remove nutrients. Untreated sewage has been entering the shallow waters up there.” Discarded piles of litter at the abandoned gulag fish factory, Khuzhir. Image: Stephen M. Bland I took a hydrofoil across the lake to Ust-Barguzin, the boat cutting through swathes of smoke rising from the mainland. In this remote hamlet of feral dogs and high-walled compounds, we docked at a port choked with the rusting hulks of half-sunken ships. In an effort to dampen the acrid fumes, some residents had hung wet cloths across their windows. Despite being home to some 7,000 people, the sewage treatment facilities in Ust-Barguzin are, according to Timoshkin, “completely destroyed.” With tourist numbers around Baikal rapidly increasing from 300,000 in 2009 to 1.3 million in 2015, according to the Siberian Times, infrastructure is struggling to keep up with demand. “Down at the southern end of the lake, there’s a town called Listvianka,” Moore continued. “It’s a tourist mecca and the hotels there, many of which have gone up in the last fifteen years, none of them have treatment facilities, so sewage is going right into the lake.” During his group’s latest expedition, Timoshkin and his colleagues also found that a pathogen had been killing sea sponges, which naturally filter the water. In the area under investigation, “from 30 to 100 percent of branched Lubomirskia baicalensis specimens were either sick or damaged and died,” Timoshkin commented. On the shoreline near the monogorod (single-factory town) of Baikalsk lie the ruins of the Baikal Paper and Pulp Mill. The plant, from which chlorinated waste found its way into the lake, finally closed at the end of 2013—for financial, not ecological reasons—but 6.2 million tons of toxic waste still remain in the aforementioned reservoirs. The Baikal trough is located on a rift zone and should an earthquake strike, the contaminated holding pods could easily rupture, causing an ecological disaster. Buryat shaman performing a ceremony on the bluff above Maloe More. Image: Stephen M. Bland In 2014, the Moscow Times reported that the site of the old factory would be turned into a “Russian Disneyland” called "Precious Russia" following the biggest clean-up in the country’s history, projected to take six years. With the economic crisis continuing though, those plans have now been shelved. “I just don’t think Russia has the political will,” Moore told Motherboard. Now, with Mongolia planning to build a series of massive dams upstream, Lake Baikal is facing a challenge which Moore believes could make all other problems “pale in comparison.” The plans, which are being evaluated as part of a World Bank-funded environmental and social impact assessment, include a project to dam the Selenga River, which provides nearly 50 percent of the lake’s water. “If this dam were built then this might cause major damage to Baikal’s ecosystem,” Professor Anson Mackay of University College London told Motherboard. “The Selenga is the lake’s largest tributary. Should flow be reduced [there could be] long-term catastrophic consequences for the ecology and wildlife in and around the lake.” When NGOs met with local authorities in Irkutsk and Baikalsk last week, Mongolian plans for the so-called Shuren Hydropower Project were high on the agenda. As the Convention for the Protection of the World Cultural and Natural Heritage states that countries should not take actions that could affect World Heritage Sites in other nations, environmental groups have questioned the legality of the project. As this row rumbles on, the Russian authorities have continued to drain the lake for an existing hydroelectric station downstream, which is at least partly culpable for water levels that Jennie Sutton from NGO Baikal Wave describes as “critically low.” A source, who spoke on condition of anonymity because the source did not have authorization to speak publicly, said that despite having poured 54 billion roubles into protecting the lake over the last three years, mismanagement of government funds has seen the state of the region continue to deteriorate. Disregarding evidence to the contrary, however, the most recent report from the Ministry of Environment and Ecology on the state of Baikal maintains that the ecosystem has not undergone “any significant changes.” Ruminating on what needs to be done to save the lake, which he describes as “seriously ill,” Timoshkin says he is calling for the introduction of a more effective system of government monitoring. He is not alone in concluding that the current approach is only fit to “diagnose cancer in the last stage.” UNESCO has accused Moscow of "dereliction of duty," per Deutsche Presse-Agentur, with regard to its handling of the Baikal region. As the sun set, having completed their daily pilgrimage to the sights, a clutch of minivan drivers returned tourists to Khuzhir. Beneath ominous skies, Russian holidaymakers hit the bars, discarding their trash as they tottered down the dung-spattered streets. Illegal campfires illuminated the dusky woods along the Maloe More Strait. Mats of algae and flotsam washed to shore. With more of Baikal than ever before open to tourism, dependence on this source of income continues to grow. The future is uncertain for a lake that until recently was considered the cleanest on Earth. Clarification: This story originally referred to Lake Baikal as the "largest" lake in the world. It's the largest by volume, unless you count the Caspian Sea, which is a matter of debate. Baikal, however, is definitely the deepest freshwater body on Earth, which makes for a clearer headlines, so we've referred to it as such. The body of the story never referred to Lake Baikal as the world's largest lake. Apologies for any confusion.

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