Quaternary and extant euryhaline Lamprothamnium Groves (Charales) from Australia: Gyrogonite morphology and paleolimnological significance

Charophytes are very common in Australian modern and Quaternary waterbodies, and are quite commonly incorrectly reported as “Chara” sp. or Lamprothamnium papulosum (Wallroth) Groves. This paper is the first attempt at the identification of the widespread euryhaline genus Lamprothamnium in Australia, and its use as a paleoenvironmental indicator. Lamprothamnium is distributed worldwide in all continents, except north and central America. The Australian environment, characterized by increasing aridity during the last 500 ka, has an abundance of saline lakes. We sampled 30 modern lakes and identified extant Lamprothamnium macropogon (A. Braun) Ophel and Lamprothamnium succinctum (A. Braun in Ascherson) Wood. Fossil gyrogonites, from lacustrine sediments ∼65 ka old from Madigan Gulf, Lake Eyre, were identified as Lamprothamnium williamsii sp. nov. We applied statistical analysis (analysis of variance, ANOVA) to the morphometry of the gyrogonites from one fossil and three living Lamprothamnium populations. The ANOVA test suggests all the populations are different, including two separate populations of extant L. macropogon, interpreted in this case as the expression of ecophenotypic variability. Lamprothamnium is a useful paleoenvironmental indicator because it indicates a non-marine environment with varying salinity ranging from fresh (usually 2–3 g l⁻¹) to 70 g l⁻¹, and water bodies holding water for at least 70 consecutive days. Collectively, these parameters provide important information in the study of ephemeral habitats.     

Pleistocene Charophyta from Arroyo Perucho Verna,Province of Entre Rios,Argentina

The Pleistocene charophytes from Arroyo Perucho Verna, Province of Entre Ríos, were analyzed.Chara contraria Br. ex Kütz.,C. contraria var.longilinea Cáceres,C. globularis Thuill. andTolypella intricata (Trent. ex Roth.) Leonh. var.apiculata (A. Br.) Wood were described and illustrated with scanning electron microscope. The assemblage indicates fresh alkaline to slightly saline waters, not very deep, in a lentic or sometimes lotic environment. Extant assemblages provide data for this paleoecological reconstruction.This is the sixth in a series of papers published in this issue on Paleolimnology in Southern South America. Dr. C. A. Fernandéndez served as guest editor for these papers.     

Charophytes from the warm springs of Svalbard

Two of Svalbard' Trollkjeldane (Troll Springs) have a luxuriant vegetation of charophytes. This article is based on material collected in the Trollkjeldane by Sissel Aarvik, of the Office of the Sysselmann (Governor) of Svalbard, on 28 August 1992 and 16 August 1993. Chara canescens is described, based on living material. The Svalbard specimens have been named Chara canescens f. spitsbergensis comb. nov., which is synonymous with Chara aspera f. spitsbergensis Nordstedt. An imperfect charophyte is described here as a new subspecies of C. canescens: Chara canescens subsp. hoelii, named after Adolf Hoel, who first collected specimens of this subspecies. It is believed that this subspecies originates from Chara canescens, presumably by a genetic reorganization or a mutation of the species. A new subspecies is justified because of the ecorticate internodes, the incomplete or lacking cortex of the branchlets, the occurrence of accessory branchlets and the special bulbils found in this taxon. These are interpreted as characteristics with positive selective value in the special environment of the spring, where asexual reproduction by bulbils presumably has the same selective value as the parthenogenic reproduction by oospores in Chara canescens f. spitsber- gensis.
In a growth experiment, the best growth of C. canescens f. spits- bergensis from the springs was obtained in water with relatively low salt content.
Growing tourism in Svalbard threatens to the springs; more active protection must be evaluated. There is also an urgent need to survey the springs in more detail.     

Post-Wisconsinian paleoenvironments at Salinas del Bebedero basin, San Luis, Argentina

We present a climatic reconstruction of Holocene lacustrine episodes in the Salinas del Bebedero basin (Argentina), based on geological and diatom information.Morphological, sedimentological and diatom evidence between 11600 ± 140 yr BP and 325 ± 95 yr BP, allowed us to interpret the paleoenvironments of the basin. Episodes of high energy (sandy levels) are linked to large inflow of meltwater through the Desaguadero River, related to development of glaciers on the Andes. This inflow is characterized by peaks of relative abundance of the brackish water diatom Cyclotella choctawatcheeana Prasad. The values of C. choctawatcheeana decrease in deposits of low energy (clay levels), where it co-dominates with oligohalobous Fragilaria and Epithemia spp.To the last two peaks of large inflow of meltwater, radiocarbon dates corrected to sidereal ages, are AD 1280/1420 and AD 1443/1656. These ages agree with two cold episodes clearly recorded in dendrological studies from the Patagonian Andes and were correlated to the Little Ice Age. Thus, older Holocene episodes of large inflow of water to the basin were correlated with the Neoglacial Advances defined by Mercer (1976) for the Andes.     

A long-term annual water balance analysis of the Araçuaí|River Basin, Brazil

Semi-arid and arid areas exhibit great temporal variability in water availability. In some of these regions, a one- or two-day rainfall is followed by intervening dry periods of variable length. In recent decades, many rivers of the semi-arid portion of the Jequitinhonha Basin have been undergoing a progressive discharge reduction, mainly of their base flow, the Araçuaí River is one of them. In order to understand this transformation, a long-term analysis of the annual water balance of the Araçuaí River Basin was performed, the results of which are presented herein. Satellite images, hydrometeorological and river discharge data were analyzed; mean and variance tests were conducted to determine temporal homogeneity. Historical pluviometric data analysis shows no corresponding precipitation reduction and temperature undergoes only a slight increase in the same period. On the other hand, evaporation is extremely high, higher than precipitation during most of the year, leaving almost no water for infiltration (aquifer recharge) and runoff. Furthermore, the Araçuaí headwaters of its tributaries are now occupied by a monoculture, Eucaliptus sp., used for paper production. Because of the decreased fluvial discharges, its lowlands, usually used for agriculture and pasture, are abandoned and partially eroded.     

A Petroleum System for the Salina Basin in Kansas Based on Organic Geochemistry and Geologic Analog

The Salina Basin historically has been an exploration desert—a home of dryholes. Although this basin, which underlies much of north-central Kansas, may never be a prolific source of hydrocarbons, recent research into the maturation and geochemistry of organic matter and oils in Kansas can provide guidelines for a new exploration strategy. The Salina Basin is similar to the oil-productive Forest City Basin in northeastern Kansas in many ways. Both basins originated as a single large basin (i.e., the North Kansas Basin) prior to the rise of the Nemaha Uplift in Late Mississippian-Early Pennsylvanian time. Their Paleozoic stratigraphy thus is similar and the axes of both basins are presently at approximately the same depth. Thermal maturation modeling and available organic-matter maturation data indicate that the lower Paleozoic rocks in the axes of both basins are in the early stages of oil generation. In the Forest City Basin the Ordovician Simpson Group is the deepest known hydrocarbon source-rock—oil-reservoir interval, and by analogy, exploration tests in the Salina Basin, at a minimum, should penetrate through this stratigraphic interval. Ordovician Simpson Group shales in the Forest City Basin are the source rocks for a geochemically distinct oil, which also occurs in Ordovician reservoirs in the extreme southern end of the Salina Basin. To increase the odds of success in an exploration program in the Salina Basin, wildcat wells should be drilled where thermal maturation is greatest. The broad NW–SE-trending basin axis is the most logical area. Exploration tests along this axis in the northern end of the basin may have an extra advantage as organic matter in the Simpson Group may be more thermally mature because of greater burial depth during the Cretaceous. Along the eastern margin of the nearby Central Kansas Uplift and Pratt Anticline, several Paleozoic geologic structures, some of which contain major oil fields, are attributable to tectonic reactivation along the western margin of the Precambrian Central North American Rift System (CNARS). Prospective structural trends in the Paleozoic section of the Salina Basin are anticipated to be associated with this underlying tectonic boundary. The western margin of the CNARS trends NNE–SSW where it passes under the axis of the Salina Basin in northeastern Lincoln and southeastern Mitchell counties. This area is sparsely drilled, with less than two tests per township. If an exploration program can define lower Paleozoic structural closures in this region, these structures may represent the best chance for future petroleum discoveries.     

Mass occurance and sporadic distribution of Corynocera ambigua Zetterstedt (Diptera, Chironomidae) in Danish lakes. Neo- and palaeolimnological records

The chironomid Corynocera ambigua (Tanytarsini) is commonly reported as a cold-stenothermal species living in shallow lakes in arctic and subarctic regions. In palaeoecological studies of temperate lakes, larval remains of C. ambigua are usually found in late-glacial sediments from the Allerød and Younger Dryas periods, and often in association with subfossil Chara oospores. During a surface sampling program of chironomid head-capsules in 41 Danish temperate lakes, C. ambigua was found to comprise 25% of the chironomid assemblages in two lakes, and was sporadically found in 8 other lakes (0.5-10%). A 70 cm palaeo-stratigraphy from the shallow (max depth 1.2 m) and eutrophic (total phosphorus = 150 g P l^-1) Lake Stigsholm showed that C. ambigua has been abundant in the last 4-5 centuries. At a sediment level of 25 cm (~year 1925, ²¹⁰Pb dating), C. ambigua began to decrease in frequency while Chironomus plumosus, Procladius sp., Cladotanytarsus gr. mancus and Tanytarsus spp. increased, suggesting an increased nutrient loading and an approach to eutrophic conditions. In 1995 C. ambigua was still very abundant in Lake Stigsholm but in early March 1997 no living larvae were found. An extremely heavy growth of Elodea, Enteromorpha and filamentous algae in the summers of 1995 and 1996, with following degradation in the fall, might have influenced the invertebrate population dynamics. No significant distinguishing characteristics were found for the lakes supporting C. ambigua. Its occurrence in warm (~20°C) Danish lakes brings into question the perception of the species as being cold-stenothermal.     

Benthos of a perennially-astatic, saline, soda lake in Mexico

The effects of multiple stressors on the benthic macroinvertebrate community were monitored in Tecuitlapa Norte, a shallow, perennially-astatic, warm, mesosaline, sodaalkaline lake in Mexico. Physico-chemical and biological variables were determined monthly for one year. Tecuitlapa Norte displayed a clear seasonal environmental pattern (dry and rainy seasons). The benthic macroinvertebrate community consisted of five species:Culicoides occidentalis sonorensis Jorgensen,Ephydra hians Say,Stratiomys sp.,Eristalis sp., andLimnophora sp. of which the first two were dominant and the rest scarce.C. occidentalis was the most important species numerically (76 percent of the total), whileE. hians dominated the biomass (73 percent of the total). Primarily salinity and secondarily pH appear to be the most important environmental factors controlling dominance of benthic organisms in Tecuitlapa Norte. Seasonal abundance dynamics of the dominant organisms was associated with phases in their reproductive cycles: environmentally-triggered (i.e., temperature rise, water-level descent) pupation and emergence periods. We concluded that whereas physical and chemical factors (i.e., salinity, pH) exerted the primary control on benthic macroinvertebrate community composition in Tecuitlapa Norte, another assembly of variables (e.g., water-level, temperature) influenced species distribution and abundance.     

察尔汗盐湖盐田光卤石矿成矿机理与盐田生产实用管理模型探讨

青海察尔汉盐湖是我国已探明储量的最大可溶性钾镁盐矿床,同时也是我国唯一的大型钾肥生产基地。本文根据多年对盐田生产定期取样分析的研究,系统探讨了大面积深水盐田的成矿机理与生产管理应用模型的建立与运行方法,对生产具有较强的指导意义。     

南极附近水域微小型藻类的研究 Ⅱ.南设得兰群岛邻近海域微小型浮游甲藻的分布特征

根据1987年1月17日～2月2日我国第三次南极考察期间,在南设得兰群岛邻近海域所获28个测站的甲藻样品,分析研究了微小型浮游甲藻的种类组成、数量分布和群落结构特征。经鉴定共有11属47种甲藻,其中以圆甲藻属(Gyrodinium spp.)、裸甲藻属Gymnodinium spp.)和原多甲藻属(Protoperidinium spp.)为主。网样甲藻平均丰度为(6.47×10~3个/m~3;水样甲藻平均丰度达2511.43×10~3个/m~3。微小型浮游甲藻的组成具有鲜明的南极海区的地方特点,大部分种是南极地区特有种,适宜在南极高寒海域大量繁殖;部分种为南极沿岸种或南极—亚南极冷水种;还有一部分为南极寒海域冷水种或分布较广的寒温带种;仅个别为广温广布种;南极海域出现的甲藻类分别代表着南极海域生物地理学和海洋生态学的特点。     

南极乔治王岛海军湾亨内克角早第三纪晚期孢粉化石及其地层学意义

根据乔治王岛海军湾亨内克角群上部凝灰质砂泥岩夹层中的孢粉化石组合特征,讨论其时代归属和沉积环境。研究表明亨内克角群上部火山沉积岩中孢粉化石共４０余种,主要成分为冈瓦纳早第三纪群落,属Ｗｅｄｄｅｌｉａｎ生物地理区,Ｎｏｔｈｏｆａｇｉｄｉｔｅｓ为代表分子,其中Ｎ．ｃｆ．ｓａｒａｅｎｓｉｓ和Ｎ．ｃｆ．ｆｌｅｍｉｎｇｉ的存在以及Ｐｒｏｔｅａｃｉｄｉｔｅｓｓｐｐ．的缺失,提示含化石地层时代可能属渐新世,沉积环境为近中低山区的湖沼环境,气候温暖潮湿。     

板寨地下河大型水生植物调查及其固碳评价

为深入研究板寨地下河流域水生植物种类及其固碳潜力,于2014―2016年在植物高生长期和生长结束期对流域内水生植物进行物种鉴定及优势水生物种确定。最终通过对优势种群开展生物量及δ13Ｃ测试,推算其固碳潜力。结果表明：1）该地下河有大型水生植物28科、35属、41种,按其经济价值来分,可食用的6种,药用的33种,观赏的20种,具有较大经济开发潜力。2）流域内黑藻（Hydrilla verticillata）、竹叶眼子菜（Potamogeton malaianus）、小眼子菜（Potamogeton pusillus）、普生轮藻（Chara vulgaris）和金鱼藻（Ceratophyllum demersum）为优势种群,其生物量依次为136.70、225.00、16.00、172.00、17.00 g/m2。3）板寨地下河水生植物光合作用的固碳能力竹叶眼子菜最大,为111.83 gC/（a·m2）,小眼子菜最小,为7.95 gC/（a·m2）。4）板寨地下河水生植物利用作用碳源的比例平均为23.21％,即板寨地下河出口至下游无机碳年通量的损失量中,约23.21％是被水生植物固定下来,其固定的碳量为14.39 gC/（a·m2）,说明水生植物光合作用与岩溶作用相结合表现出巨大的固碳潜力。     

Bathonian and Callovian (Middle Jurassic) dinoflagellate cysts and acritarchs from Franz Josef Land, Arctic Soviet

Well preserved dinoflagellate cyst and acritarch assemblages are recorded from Upper Bathonian and Callovian deposits on Northbrook Island, Franz Josef Land. More than 45 species have been identified. Two new species are proposed: Parvocysta bjaerkei sp. nov., and Meiourogonyaulax spongiosa sp. nov. The recorded marine microfloras are compared with assemblages reported from contemporaneous strata in Svalbard.     

Phytoplankton composition and dynamics in three shallow temporary salt lakes (Monegros, Spain)

The present study deals with phytoplankton composition and dynamics of three ephemeral saline lakes (La Muerte, Piñol and Sulfúrica) situated in one of the most arid inland zone in Europe (Los Monegros). The lakes show marked differences among one another, although they are all temporary, shallow and saline systems (>30 g l⁻¹). La Muerte is dominated by microbial mats that are absent from the other two. Piñol is more exposed to strong winds than the other two lakes and exhibits higher turbidity. Sulfúrica appears to be the most extreme system, with the highest salinity, which leads to a complete absence of macrozooplankton. Phytoplankton composition in these lakes varies as a consequence of the different physico-chemical conditions; it is fundamentally composed of typical hypersaline species such as Dunaliella sp., Aphanothece sp., and soil benthic species (e.g. Hantzschia amphyoxis) that appear to play an important role in these systems. Comparative analysis of the microbial component (phytoplankton diversity and temporal evolution) under in situ conditions and the presence of various abiotic and biotic factors, including the impact of macrozooplankton grazing, shows that it is easy to overlook large differences in the community structure of apparently similar ecosystems. The present study is a contribution to the understanding of the often-neglected microbial ecology of ephemeral shallow lakes.     

Fluctuation in the zooplankton community in two solar salt ponds,Aveiro, Portugal

The zooplankton of two salt ponds at Aveiro was studied to evaluate its density and diversity. Samples were collected biweekly from the salt ponds Esmolas and Tanoeiras. Samples were first separated into Holoplankton (Copepoda, nauplii,Acartia, Ostracoda and Anostraca) and Meroplankton (Mollusca, Insecta, annelidan larvae and Ichthyoplankton). The Holoplankton was mainly composed of:Acartia tonsa, Acartia sp.,Eurytemora velox, Artemia sp., and harpacticoids and calanoids. In both salt ponds, species diversity was identical, but total zooplankton density was higher in the Tanoeiras salt pond, probably because its physical and chemical characteristics allowed the development of stable communities.     

Littoral benthos of the saline crater lakes of the basin of Oriental, Mexico

Two saline crater lakes in the basin of Oriental, Puebla-Tlaxcala-Veracruz, were investigated for littoral benthic macroinvertebrates. Fifty taxa were identified with the oligochaetes, amphipods, chironomids and leeches the dominant organisms. These four taxa made up to 99 per cent in both number and biomass.Limnodrilus hoffmeisteri, Hyalella azteca, Tanypus (Apelopia) sp. andStictochironomus sp. were the most abundant organisms. Unlike other saline lakes which have a littoral benthos dominated by chironomids, Alchichica and Atexcac were dominated by oligochaetes (70–73 per cent). The gastropod,Physa sp., was found up to a salinity of 8 g L⁻¹; in other studies, it has been found in lower salinities.L. hoffmeisteri is also a typical inhabitant of freshwater lakes, particularly of deep waters. It was dominant in the shallow, saline waters of the two lakes studied. Salinity did not affect species richness. Alchichica, the most saline of the six crater lakes of Puebla (salinity, 7.4 g L⁻¹), had 30 per cent more species than the freshwater lakes, and double the species number of Atexcac. It seems the main factor controlling species richness and the density and biomass of organisms in Alchichica and Atexcac is the presence of aquatic vegetation. It does this by increasing habitat heterogeneity and providing food and protection against predators.     

Report on species of Gyrodactylus Nordmann, 1832, distribution in polar regions

The aim of this study was to compare the Gyrodactylus fauna in the Arctic and Antarctic regions. Fish were collected from waters surrounding the South Shetland Islands in the Antarctic and from the Revelva River and Hornsund Fjord in south Spitsbergen in the Arctic. Eighty-two individual fish representing seven species from three families (Channichthyidae, Harpagiferidae, and Nototheniidae) were found in Antarctica and 2 Gyrodactylus infections with altogether 95 specimens were reported. Two new species were identified: Gyrodactylus sp. 1 Rokicka et al., 2009, from the gills of the black rock cod, Notothenia coriiceps Richardson, 1844, and Gyrodactylus sp. 2 Rokicka et al., 2009, from the gills of the gaudy notothen, Lepidonotothen nudifrons Lönnberg, 1905. No Gyrodactylus were found in the 95 Arctic fish examined, which represented four species from four families (Salmonidae, Gadidae, Cottidae, and Liparidae).     

Climatic change and rainfall patterns: Effects on semi-arid plant communities of the Iberian Southeast

The structure and functioning of semi-arid ecosystems are strongly influenced by precipitation patterns. Water availability in such environments is highly pulsed, and discrete rainfall events interspersed with drought periods are important components of the annual water supply. Plant communities do not only respond to rainfall quantity, but also to variations in time, so that relatively small changes in rainfall frequency (i.e., pulsed inputs) may have strong effects on communities. Within the Mediterranean basin, climate change models forecast a decrease in mean annual precipitation and more extreme events (i.e., less rainy days and longer drought periods between events), along with seasonal changes. However, little is known on the consequences of these future precipitation changes on plant communities, especially in semi-arid environments. Here, we summarize the few experiments that have manipulated rainfall patterns in arid and semi-arid areas worldwide, and introduce the first results of a pioneer, long-term rainfall exclusion in the semi-arid southeast region of the Iberian Peninsula. The experiment is not only manipulating the amount of rainfall, but also its frequency and seasonal distribution in a grassland-shrubland in the Tabernas desert (Almería, Spain). This work monitored the effect of precipitation changes on different ecosystem processes for five years, at the species and community level, concluding that this plant community (as other communities studied in the same area) exhibited great resilience to changes in rainfall availability, likely caused by plant adaptation to large intra- and inter-annual precipitation variability.     

FRESHWATER ALGAE COMMUNITY OF A MELTWATER RUNNEL,REEVE HILL, CASEY STATION, ANTARCTICA

Researches on the Antarctic microalgal diversityand distributions in the freshwater environment ran-ging from snow to large lakes and well-definedstreams are extensive.For instance,studies on thestream microalgal community have been conducted onthe Pervay…