Alkaline soda Lake Velika Rusanda (Serbia): the first insight into diatom diversity of this extreme saline lake

Alkaline soda lakes are unique habitats found in specific geographic regions, usually with dry climate. The Carpathian Basin is one of those regions very important for habitat and biodiversity conservation in Europe, with natural soda lakes found in Austria, Hungary and Serbia. In comparison to other two countries from Central Europe, algal biodiversity studies of saline soda lakes in Serbia are scarce. Lake Velika Rusanda has the highest measured salinity of all saline lakes in the Carpathian Basin and there were no reports of its diatom species richness and diversity till now. We conducted 2-year investigation programme to study biodiversity and seasonal dynamics of diatoms in this lake. A total of 27 diatom taxa were found, almost all of them attached to reed and much less in benthos and plankton. Five new diatom species for Serbia were recorded, Craticula halopannonica, Navicymbula pusilla, Hantzschia weyprechtii, Nitzschia thermaloides and Navicula staffordiae. The last mentioned is new for Europe as well. Lake Velika Rusanda is inhabited mostly by alkaliphilous and halophilic diatoms. Since diatoms are used as bioindicators in soda lakes, our results will improve their further application in ecological status assessment of these fragile habitats in the Carpathian Basin.

     

The mammals of northern Melanesia: speciation,ecology, and biogeography

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Sedimentary diatom assemblages in the northern part of Lake Tanganyika

Surface sediment diatoms from the northern part of Lake Tanganyika were analysed with several ordination and classification techniques. Three sample groups characterized by four diatom assemblages were recognized. The first sample group occurs in a rather shallow area near the delta of the Rusizi River on a coarse-grained sand substrate. The second and most important sample group occurs on the silty bottom of an underwater depression situated off the delta of the Rusizi River in the north-eastern part of Lake Tanganyika; its diatom composition has a great affinity to the Rusizi River diatom population. The third sample group contains all the other samples and covers an area corresponding to the west-, east- and southward continuation of the area of the second group: its diatom composition is also related to the Rusizi River diatom population, but in a less pronounced manner.     

On the use of measures of structure and diversity in applied diatom ecology

Water managers ask for simple ecological indices as a tool for measuring the effectiveness of their activities. Diversity indices are often used as such tools. The concept of diversity is closely related to the nature of species-abundance distributions. There is empirical and theoretical evidence that diatom-assemblages have a species-abundance distribution of log-series type. Then the most appropriate diversity index is the dominance,i.e. the relative abundance of the commonest species. The number of species in a sample of fixed size of the assemblage is a useful additional index. It appears from some examples that these indices have no consistent relationships with the degree of water pollution. This in contrast to the species composition of the assemblages. (Complete paper published in: HAKANSSON, H. and J.GERLOFF, Eds., (1982). Festschrift Niels Foged. Diatomaceae III. Beiheft zur Nova Hedwigia     

Centric diatom algae (Centrophyceae) of ultraoligotrophic Lake Elgygytgyn and water bodies of its basin (Chukotka,Russia)

The electron microscopy study of algae from Lake Elgygytgyn and the water bodies of its basin has revealed 21 taxa of centric diatoms of specific and intraspecific ranks. Nine new species and varieties have been found, including Aulacoseira distans var. nivaloides, A. distans var. septentrionalis, Discostella guslyakovyi, which are rare for the flora of Russia; an endemic species (?) Pliocaenicus seckinae; and six interesting forms from the genus Aulacoseira identified only to the genus. The list of Centrophyceae of Beringia has been broadened.     

First investigation of ultraoligotrophic alpine Lake Puma Yumco in the pre-Himalayas,China

Lake Puma Yumco is a typical alpine lake (altitude 5030m) located in the pre-Himalayas of Tibet, China, and this study was the first limnological investigation ever conducted on it. Lake Puma Yumco (28°34N, 90°24E) has the following morphometric properties: maximum length 31km, maximum width 14km, mean width 9km, shoreline 90km, surface area 280km², and shoreline development 1.5. Transparency was approximately 10m, even in the thawing season. The extinction coefficient of the lake water was calculated as 0.15m^–1. Annual maximum transparency was estimated from the depth of the Chara zone to be 30m. Dissolved oxygen was 7mg O₂ l^–1 and showed saturated values, and salinity was 360mgl^–1. The chemical type of the lake water was Mg-Ca-HCO₃-SO₄, and it was slightly alkaline in character. Total nitrogenous nutrients (sum of ammonia, nitrite, nitrate, and urea nitrogen), phosphate, and silicate were extremely low at 1, 0.02, and 9µM, respectively. Dissolved organic carbon, nitrogen, and phosphorus concentrations were 160, 11, and 0.08µM and the molar ratio was calculated as 2100:140:1. Chlorophyll a concentration was 0.2mgm^–3. Phytoplankton and zooplankton were dominated by Aphanocapsa sp. and Diaptomidae. Both nitrogen and phosphorus appear to be the limiting parameters for phytoplankton growth. Organic carbon and nitrogen contents in lake sediments were low and the sediments contained a large amount of CaCO₃. The grain size of sediment was that of silt-sand in most cases. The present results indicate that the pre-Himalayan alpine freshwater Lake Puma Yumco is an ultraoligotrophic lake.     

Current patterns of macroalgal diversity and biomass in northern hemisphere rocky shores

Latitudinal gradients in species abundance and diversity have been postulated for nearshore taxa but few analyses have been done over sufficiently broad geographic scales incorporating various nearshore depth strata to empirically test these gradients. Typically, gradients are based on literature reviews and species lists and have focused on alpha diversity across the entire nearshore zone. No studies have used a standardized protocol in the field to examine species density among sites across a large spatial scale while also focusing on particular depth strata. The present research used field collected samples in the northern hemisphere to explore the relationships between macroalgal species density and biomass along intertidal heights and subtidal depths and latitude. Results indicated no overall correlations between either estimates of species density or biomass with latitude, although the highest numbers of both were found at mid-latitudes. However, when strata were examined separately, significant positive correlations were found for both species numbers and biomass at particular strata, namely the intertidal ones. While the data presented in this paper have some limitations, we show that latitudinal macroalgal trends in species density and biomass do exist for some strata in the northern hemisphere with more taxa and biomass at higher latitudes.     

Diversity, ecology and biogeography of the freshwater diatom communities from Ulu Peninsula (James Ross Island, NE Antarctic Peninsula)

The diversity, ecology and biogeography of diatoms in lakes, seepage areas and streams on the Ulu Peninsula, a large ice-free area in the northern part of James Ross Island (Weddell Sea), were studied. A diverse diatom flora of 123 taxa was observed, dominated by several Nitzschia taxa, Psammothidium papilio, Eolimna jamesrossensis, Fragilaria capucina and Fistulifera saprophila. The results from the similarity and diversity analysis suggest James Ross Island to be biogeographically positioned within the Maritime Antarctic region, yet with some affinities with the flora of Continental Antarctica, as shown by the presence of Luticola gaussii and Achnanthes taylorensis. Based on our data, James Ross Island can thus be located close to the boundary of the two main Antarctic biogeographical regions. Diatom communities present in streams and seepage areas could be clearly distinguished from those in lakes, the latter being much more species rich. Based on the multivariate analysis, conductivity and nutrients were selected as the two main environmental factors determining the diatom composition in the Ulu Peninsula lakes. The revised taxonomy of the Antarctic diatom flora induced the construction of a transfer function for water conductivity in the studied lakes that can be applied in further palaeoecological studies.     

Spatial patterns of diatom diversity and community structure in ancient Lake Ohrid

For effective lakes’ management, high-frequent water quality data on a synoptic scale are essential. The aim of this study is to test the suitability of the latest generation of satellite sensors to provide information on lake water quality parameters for the five largest Italian subalpine lakes. In situ data of phytoplankton composition, chlorophyll-a (chl-a) concentration and water reflectance were used in synergy with satellite observations to map some algal blooms in 2016. Chl-a concentration maps were derived from satellite data by applying a bio-optical model to satellite data, previously corrected for atmospheric effects. Results were compared with in situ data, showing good agreement. The shape and magnitude of water reflectance from different satellite data were consistent. Output chl-a concentration maps, show the distribution within each lake during blooming events, suggesting a synoptic view is required for these events monitoring. Maps show the dynamic of bloom events with concentration increasing from 2 up to 7 mg m^?3 and dropping again to initial value in less than 20 days. Latest generation sensors were shown to be valuable tools for lakes monitoring, thanks to frequent, free of charge data availability over long time periods.     

The diatom flora in the ultra-oligotrophic Lake El'gygytgyn,Chukotka

Lake El'gygytgyn, an impact crater lake in northeastern Siberia, was analysed based on water-column characteristics and the modern and sub-recent diatom flora. Vertical temperature, conductivity and oxygen profiles, as well as ionic concentrations in the lake water, reveal that Lake El'gygytgyn is a clear, cold-monomictic, ultra-oligotrophic high-Arctic lake with high light-penetration depth. We identified 113 diatom taxa, of which only 2 species are planktic diatoms. Cyclotella ocellata is the only quantitatively significant diatom present in the modern phytoplankton community, and is also predominant in a short sediment core, which probably reflects the mid- and late-Holocene environmental history of Lake El'gygytgyn. Pliocaenicus costatus var. sibiricus is also common but of minor importance. This is the first evidence of P. costatus var. sibiricus outside the Lake Baikal region.     

Microbial ecology of an extreme acidic environment,the Tinto River

The Tinto River (Huelva, southwestern Spain) is an extreme environment with a rather constant acidic pH along the entire river and a high concentration of heavy metals. The extreme conditions of the Tinto ecosystem are generated by the metabolic activity of chemolithotrophic microorganisms thriving in the rich complex sulfides of the Iberian Pyrite Belt. Molecular ecology techniques were used to analyze the diversity of this microbial community. The community's composition was studied by denaturing gradient gel electrophoresis (DGGE) using 16S rRNA and by 16S rRNA gene amplification. A good correlation between the two approaches was found. Comparative sequence analysis of DGGE bands showed the presence of organisms related to Leptospirillum spp., Acidithiobacillus ferrooxidans, Acidiphilium spp., "Ferrimicrobium acidiphilum," Ferroplasma acidiphilum, and Thermoplasma acidophilum. The different phylogenetic groups were quantified by fluorescent in situ hybridization with a set of rRNA-targeted oligonucleotide probes. More than 80% of the cells were affiliated with the domain Bacteria, with only a minor fraction corresponding to ARCHAEA: Members of Leptospirillum ferrooxidans, Acidithiobacillus ferrooxidans, and Acidiphilium spp., all related to the iron cycle, accounted for most of the prokaryotic microorganisms detected. Different isolates of these microorganisms were obtained from the Tinto ecosystem, and their physiological properties were determined. Given the physicochemical characteristics of the habitat and the physiological properties and relative concentrations of the different prokaryotes found in the river, a model for the Tinto ecosystem based on the iron cycle is suggested.     

Combining ecology,human demands,and philosophy into the management of northern pike in Michigan

Northern pike (Esox lucius Linnaeus) are a common sportfish native to most waters in Michigan. Early use of northern pike was unregulated consumptive harvest. Pike anglers today vary from those interested in intense harvest, to winter spear fisheries, to those interested in catching trophy fish. Michigan pike are now managed within three ecological groupings: 1. High density and slow growing populations, managed to increase harvest and reduce density (managed with a daily bag limit of 5 fish and no size limit). 2. Moderate density populations with normal growth (most populations, managed with a 61-cm (24-in) size limit and creel of 2 fish per day). 3. Low density and rapid growing populations (managed for trophy fisheries with a 76-cm (30-in) size limit and restricted take). Recent management challenges also include loss of wetland-spawning habitat, driving a need for stocking to supplement natural reproduction. Michigan has managed spawning marshes and other habitat to produce northern pike from natural waters, and recent demand has led to hatchery production of fry. Technology for hatchery production has moved from extensively growing pike and stocking at a small size to the current system using pelleted feed, growing fish to a larger size at a lower density. Future plans for pike management in Michigan are even more focused on using ecology as a means to manage lakes and streams, but will require much more research to be feasible. Guest editors: J. M. Farrell, C. Skov, M. Mingelbier, T. Margenau & J. E. Cooper International Pike Symposium: Merging Knowledge of Ecology, Biology, and Management for a Circumpolar Species     

Taxonomic diversity of the terrestrial bird and mammal fauna in temperate and boreal biomes of the northern hemisphere

Abstract. Using comprehensive range information of northern Hemisphere birds and mammals, we assessed the taxonomic diversity of these two groups in four different regions: Europe, east Asia, and western and eastern North America. East Asia is the richest region in the number of bird and mammal species, genera, families and orders, except that mammal species richness is highest in western North America. Eastern North America is taxonomically the poorest region, but when only forest-associated taxa were considered in mammals taxonomic diversity is equally low in Europe and in eastern North America, and in birds, Europe is the least diverse region. Patterns in endemic taxa follow overall taxonomic diversity. The proportion of shared taxa between regions is higher among boreal species and genera than among all taxa. A comparison with tree species diversity underpins the role of east Asia as the most diverse of all northern biota. Largely congruent patterns at different taxonomic levels emphasizes the role of historical processes, such as differential extinction rate in response to paleoenvironmental fluctuations, in producing these patterns, but we stress the need for more research on the coevolution of species diversity and habitat diversity.     

Morphometry,biogeography and ecology of Calcidiscus and Umbilicosphaera in the South Atlantic

Here we present morphometrical evaluation, biogeographical distribution patterns and ecological information for five coccolithophore taxa (Calcidiscus leptoporus, C. leptoporus small, C. quadriperforatus, Umbilicosphaera foliosa and U. sibogae). This information is based on data obtained from surface sediments from the South Atlantic. The three Calcidiscus taxa can easily been distinguished by a combination of size and qualitative characters of their distal shields. Mostly encountered in the temperate to sub-polar regions C. leptoporus is the most abundant taxon and exhibits a negative correlation to temperature and salinity. Both, C. leptoporus small and C. quadriperforatus reach their maximum abundances also at higher latitudes and in the SW-African upwelling area. Their distributions therefore suggest preference for nutrient-enriched waters, which is also indicated by CCA. The two circular Umbilicosphaera species exhibit significant differences in coccolith morphology and show little overlap in size. Highest abundances are encountered in sub-tropical latitudes and are mainly derived from U. sibogae. In contrast, U. foliosa is present in very low abundances. Both species exhibit a preference for warm and oligotrophic conditions. However, U. foliosa increases in relative proportion to U. sibogae at the southernmost locations and in the Benguela upwelling. This could be interpreted as an affinity for slightly cooler and nutrient-enriched environments.     

Early Hominid diversity, age and biogeography of the Malawi-Rift

Remains of earlyHomo andParanthropus have been recovered from two contemporaneous sites (Uraha and Malema) in the “Hominid Corridor” in Northern Malawi (Chiwondo Beds). Faunal dating suggests an age of 2.5–2.3 Ma for both hominids. The two specimens, a mandible attributed toHomo rudolfensis (UR 501 from Uraha), and a maxillary fragment ofParanthropus boisci. (RC 911 from Malema) known only from eastern Africa, represent the southernmost known distribution of these taxa. The biogeographic significance of these hominids from the Malawi-Rift lay in their association with the eastern African endemic animal group. Biogeographic variation in south-eastern Africa may be linked to habitat change occurring due to climate change, with maximum change occurring around 2.5 Ma.     

Further insight into the genetic diversity of Entamoeba coli and Entamoeba hartmanni

Despite the species' wide distribution, studies of the genetic diversity within Entamoeba coli and Entamoeba hartmanni remain limited. In the present study, we provide further insight into the genetic diversity of both species based on analysis of partial nuclear small subunit ribosomal DNA sequences generated from human fecal DNAs from samples collected in Africa, South America, and Europe. Reinforcing the previous recognition that E. coli is a species complex, our data confirm the existence of the two subtypes, ST1 and ST2, previously identified plus, potentially, a new subtype, ST3. While ST1 appears to be genetically quite homogenous, ST2 shows a substantial degree of intrasubtype diversity. ST2 was more common in samples collected outside Europe, whereas ST1 showed no geographical restriction. The potentially novel subtype is represented to date exclusively by sequences from South American and African samples. In contrast to previous reports, our new data also indicate substantial variation in E. hartmanni that could also support the establishment of subtypes within this species. Here, however, no links were identified between subtype and geographical origin.