Spatio-temporal insights into microbiology of the freshwater-to-hypersaline, oxic-hypoxic-euxinic waters of Ursu Lake

Ursu Lake is located in the Middle Miocene salt deposit of Central Romania. It is stratified, and the water column has three distinct water masses: an upper freshwater-to-moderately saline stratum (0–3 m), an intermediate stratum exhibiting a steep halocline (3–3.5 m), and a lower hypersaline stratum (4 m and below) that is euxinic (i.e. anoxic and sulphidic). Recent studies have characterized the lake's microbial taxonomy and given rise to intriguing ecological questions. Here, we explore whether the communities are dynamic or stable in relation to taxonomic composition, geochemistry, biophysics, and ecophysiological functions during the annual cycle. We found: (i) seasonally fluctuating, light-dependent communities in the upper layer (≥0.987–0.990 water-activity), a stable but phylogenetically diverse population of heterotrophs in the hypersaline stratum (water activities down to 0.762) and a persistent plate of green sulphur bacteria that connects these two (0.958–0.956 water activity) at 3–3.5 to 4 m; (ii) communities that might be involved in carbon- and sulphur-cycling between and within the lake's three main water masses; (iii) uncultured lineages including Acetothermia (OP1), Cloacimonetes (WWE1), Marinimicrobia (SAR406), Omnitrophicaeota (OP3), Parcubacteria (OD1) and other Candidate Phyla Radiation bacteria, and SR1 in the hypersaline stratum (likely involved in the anaerobic steps of carbon- and sulphur-cycling); and (iv) that species richness and habitat stability are associated with high redox-potentials. Ursu Lake has a unique and complex ecology, at the same time exhibiting dynamic fluctuations and stability, and can be used as a modern analogue for ancient euxinic water bodies and comparator system for other stratified hypersaline systems

Preliminary data on the ornithological fauna of the islet forming in the south part of Musura Gulf , between Stambulul Vechi (Ukraine) and Sulina (Romania) branches of the Danube

For several tens of years, Sacalin Island has been regarded as the classic example of a new biotope forming in the easternmost part of the Danube, resulted as an interaction between the river and the Black Sea, host to specific flora and fauna; presently, the island tends to become a maritime levee, gradually joining the mainland and Holinca levee. Therefore, the area is losing its physical and geographical features as a new formed territory, including its unique characteristic as an optimal site for the establishment of waterbird colonies. A similar process of islet forming has been recently taking place in the east part of Musura Gulf, between Stambulul Vechi - Starâi Stambul (Ukraine) and Sulina (Romania) branches. The Ukrainian name of the site is Novaia Zemlia – New Land, and the country borders have already been marked. The new formed islets host a rich and diverse ornithological fauna, dueto their location and spatial orientation. On the Romanian side of the site, the reappearance of Sandwich Tern (Sternasandvicensis) colonies, represented by a great number of pairs, as well as Common Terns (Sterna hirundo), has been noted. Also, the site hosts the largest Caspian Gull (Larus cachinnans) colony in the country; the breeding of the Avocet (Recurvirostra avosetta) and of the Oystercatcher (Haematopus ostralegus) has been documented. The observations performed up to present lead us to conclude that this new formed land is a model for the evolution of river-maritime sandbanks as a result of sedimentation; it is also of a major ornithological importance for the roosting, feeding and nesting ofboth sedentary and migratory species. Further monitoring is imperative in order to designate the site as a core area andresearch based on transboundary cooperation is required

Preliminary data concerning ornithofauna of the Babadag lake area

The ornithological observations were carried out in the Babadag Lake area and its surroundings (Tauc and Topraichioi lakes) in 2008 and 2009. The purpose of the study was to put up-to-date the data concerning qualitative analysis of the ornithofauna from the Babadag Lake area. Were counted 91 species of birds, of them 80 species arenesting in the Babadag Lake area. The identified bird species belong to 12 orders, 36 families and 65 genera. There was found one of the largest colonies of Sand Martin (Riparia riparia) from the Dobrogea Tableland and also from Romania, over 2,000 pairs

The evaluation of the environmental quality in Romania

The evaluation of the environmental quality concerns the analysis of the physical, chemical, biological and statistical features that allow the scientists to classify a territory in a certain category or hierarchic scale. In the model used in this study, the environmental quality was assessed at the administrative unit level (county), as a result of the interaction of different components. Fifty indicators were selected and included into 6 major groups based on several factors (natural hazards, air quality, biodiversity, water quality, human health, soil quality, economic activities) that increase the communities' susceptibility to different negative aspects concerning the environment. Each indicator was classified on a scale from 1 to 5 (1-very good…5-very weak). The sum of the indicators was reclassified according to the same model, until the total environmental quality was finally determined. The analysis of the environmental quality on a departmental level provides the opportunity to identify the regions that need to be allotted financial resources in order to diminish the negative impact of the disturbing (anthropic and natural) factors. At the same time, by focusing the research on the most vulnerable counties, a more detailed analysis has revealed the most vulnerable administrative units (towns and communes)

Data on the postbreeding migration of marked Romanian Great White Pelicans (Pelecanus onocrotalus Linnaeus, 1758)

Between 1931 and 2018 in the Danube Delta, 1,171 Great White Pelican (Pelecanus onocrotalus Linnaeus 1758) were ringed (731 with metal rings, 440 with coloured plastic rings) at breeding sites. The majority of the captured birds were flightless young individuals. From the ringed birds, 25 (2.13%) were reported as recaptured. Most were reported from Israel (28%), and the rest from 8 other countries. Recovery distance varied between 50 and 3,000 km. 19 birds (76%) were reported within half year after ringing, 2 birds (8%) within a year, and further 4 individuals (16%) were reported after a year. With the exception of a single photographed individual, all the others perished: they were shot or fell victims to accidents. These cases suggest high mortality in the young age cohort. Very little knowledge is available about the African wintering grounds; there are only two reports from Egypt and one from Southern Sudan. Traditional ringing yields little information for this species. Considerably more exact data could be expected from satellite tracking, use of other modern locating techniques and use of genetic methods. The ringing of nestlings is only possible if we can apply less aggressive methods then used to date. Besides its scientific value, the intense research on the still numerous Great White Pelican population would be justified by the outstanding faunistic, economic and cultural importance of this species

Data on the distribution of the Greater Black-headed Gull (Larus ichthyaetus Pall. 1773) and its breeding in the Danube Delta Biosphere Reserve

In the present article the authors provide data on the first record of the breeding in Romania of the Greater Black-headed Gull (Larus ichthyaetus). The colony was identified on June 4th, 2009, on a new island located in the Musura gulf, at the north-eastern border of the Danube Delta (Danube Delta Biosphere Reserve)

New nesting site for Dalmatian Pelican elecanus cispus in a polyspecific colony of aquatic birds on Taaul Lae Romania

In the Natura 2000 site, ROSPA 0060 Taşaul - Corbu Lakes, the nesting of Dalmatian Pelican (elecanus crispus Bruch 1832) have been confirmed in 2016. The presence of the species in the breeding season was regurarly recorded in this location since 2008. The novelty is that it is the first proved nesting of the species in Romania, except the Danube Delta Biosphere Reserve perimeter, in the last 100 years. The colony is located on the La Ostrov island on Taşaul Lake (Constanţa county). The island hosts a polyspecific colony of aquatic birds, 5 species being recorded during our investigations. In the first phase several counts have been performed from the lake shore using adequate optical equipment and on 24th of June 2016 a direct count on the island have been done. The colony comprises 3 orders elecaniformes, iconiiformes and haradriiformes: Dalmatian Pelican (elecanus crispus) - 12 pairs, 800-900 pairs of Great Cormorant (halacrocora carbo), 100-200 pairs of Little Egret (gretta garetta), 30-50 pairs of Night Heron (Ncticora ncticora) and about 1,000 pairs of Caspian Gull (arus cachinnans). Monitoring of the colony should continue in the following years. Access to the island should be allowed only outside the breeding season of the Dalmatian Pelicans. The colony should be treated as a core area in Natura 2000 sit

Considerations regarding the occurence of the Eurasian Beaver (Castor fiber Linnaeus 1758) in the Danube Delta (Romania)

On its original Romanian name - breb, the Eurasian Beaver (Castor fiber) extinct at us for almost two centuries and reintroduced in some areas of the country, at present is better known under the name of his North American relative, beaver. In the last decades, this specie has been reintroduced within in its old habitats from where itwas extinct, especially under the effect of human pressure. Since 1998, reinsertion actions took place in Romania, in many areas, the closest one to Danube Delta area being the lower part of Ialomita river. By 2011 epigraphic or paleozoology evidences about the presence of this mammalian into the actual Delta have not been found, except the Lower Danube, up to Isaccea, but also near Dobrogea Plateau in Murighiol area. Its last Paleontology evidences come from early medieval period. Until now, the actual delta was considered a territory inappropriate for the Eurasian Beaver, due to high fluctuations of the water levels. But, in April 2011, the spontaneous appearance of the European beaver near Maliuc area was proved, a copy killed by poachers. In July 2011, a Beaver injured after the collision with a boat was found and scientifically investigated. The future observations will have to document if this mammal extends its habitat up here or remains an erratic appearance. In case of success of spontaneous colonization, its consequences and effects on the environment in general and on biodiversity inparticular are required to be monitored

The complete sequence of a West Nile virus lineage 2 strain detected in a Hyalomma marginatum marginatum tick collected from a song thrush (Turdus philomelos) in eastern Romania in 2013 revealed closest genetic relationship to strain Volgograd 2007.

In this study the first complete sequence of the West Nile virus (WNV) lineage 2 strain currently circulating in Romania was determined. The virus was detected in a Hyalomma marginatum marginatum tick collected from a juvenile song thrush (Turdus philomelos) in the Romanian Danube Delta close to the city of Tulcea, end of August 2013. Our finding emphasizes the role of ticks in introduction and maintenance of WNV infections. Sequence analyses revealed close genetic relationship of the Romanian WNV strain to strain Reb_Volgograd_07_H, which was isolated from human brain tissue during an outbreak of West Nile neuroinvasive disease (WNND) in Russia in 2007. In 2010 the Eastern European lineage 2 WNV caused an outbreak of human WNND in Romania. Partial sequences from subsequent years demonstrated that this WNV strain became endemic in Eastern Europe and has been causing outbreaks of varying sizes in southern Russia since 2007 and in Romania since 2010

Preliminary results of the research on the West Nile Virus from the Danube Delta Biosphere Reserve

Since 2004, we have started to study the role of birds in transmission of West Nile Virus (WNV) in Danube Delta and Dobrogea Tableland (Fig. 1 and Fig. 6). Same, we want to understand the mechanism of the virus’ transmission, to know which environmental factors induce the emergence of WNV. The work was focusedon three main issues: monitoring of relevant environmental factors (biotic and abiotic) and gathering data on the factors from the past and correlate them with WNV human cases; harvesting ectoparasites of birds (lice and ticks) for testing, and verifying the hypothesis of their vectorial role; sampling a large number of wild and domestic birds and horses and testing to find out their seroprevalence. All our results will be integrated into the laboratory work of thecolleagues from the Cantacuzino Institute (they deal especially with mosquitoes research - positive species, qualitative and quantitative composition). Up to now we detected seroprevalence in birds and horses, the increasing the number of the species involved on WNV transmission and gathered relevant information on environmental factors. Sampling of birds and horses will continue for another two years in order to clarify the mechanism of emergence and dissemination of WNV