A study on distribution of natural radionuclide polonium-210 in a pond ecosystem

This paper presents the results of an investigation on the distribution of²¹⁰Po in Mutharasanallur pond ecosystem. It has been demonstrated that²¹⁰Po is non-uniformly distributed within the ecosystem. The results of the study show a dissolved²¹⁰Po concentration in pond water of 1 4mBq 1₋₁. The sediment samplso recorded a²¹⁰Po activity of 59 9 Bq kg₋₁. The aquatic organisms showed differential accumulation of the radionuclide with enhanced bioaccumulation in soft tissues and muscle. The²¹⁰Po activity in the biota fell within the range of 1·2–53 3 Bq kg₋₁ (wet wt). The bivalve mussel,Lamellidens marginalis was identified to accumulate higher concentration of²¹⁰Poin soft tissues, suggesting that these organisms could serve as a bio-monitor of²¹⁰Po radionuclide in a freshwater system. The concentration factors of²¹⁰Po for the biotic components ranged from ∼10²–∼10⁴. Analyses of the results indicate that prawn and fish represent an important source of supply of²¹⁰Po to humans via dietary intake. Results of²¹⁰Po activity in the abiotic and biotic components of the pond ecosystem were higher when compared with those of Cauvery river system, the primary water source of the pond.     

Epsilonproteobacteria Represent the Major Portion of Chemoautotrophic Bacteria in Sulfidic Waters of Pelagic Redoxclines of the Baltic and Black Seas

Recent studies have indicated that chemoautotrophic Epsilonproteobacteria might play an important role, especially as anaerobic or microaerophilic dark CO₂-fixing organisms, in marine pelagic redoxclines. However, knowledge of their distribution and abundance as actively CO₂-fixing microorganisms in pelagic redoxclines is still deficient. We determined the contribution of Epsilonproteobacteria to dark CO₂ fixation in the sulfidic areas of central Baltic Sea and Black Sea redoxclines by combining catalyzed reporter deposition-fluorescence in situ hybridization with microautoradiography using [¹⁴C]bicarbonate and compared it to the total prokaryotic chemoautotrophic activity. In absolute numbers, up to 3 × 10^{5 14}CO₂-fixing prokaryotic cells ml⁻¹ were enumerated in the redoxcline of the central Baltic Sea and up to 9 × 10^{4 14}CO₂-fixing cells ml⁻¹ were enumerated in the Black Sea redoxcline, corresponding to 29% and 12%, respectively, of total cell abundance. ¹⁴CO₂-incorporating cells belonged exclusively to the domain Bacteria. Among these, members of the Epsilonproteobacteria were approximately 70% of the cells in the central Baltic Sea and up to 100% in the Black Sea. For the Baltic Sea, the Sulfurimonas subgroup GD17, previously assumed to be involved in autotrophic denitrification, was the most dominant CO₂-fixing group. In conclusion, Epsilonproteobacteria were found to be mainly responsible for chemoautotrophic activity in the dark CO₂ fixation maxima of the Black Sea and central Baltic Sea redoxclines. These Epsilonproteobacteria might be relevant in similar habitats of the world's oceans, where high dark CO₂ fixation rates have been measured.     

Polonium-210 in fishes from the Black Sea

The specific activity of naturally occurring radionuclide 210Po in main species of the Black Sea fishes and some their organs were used for the calculation of absorbed and equivalent dose rates. The values of the dose in investigated fish depend on their ecological belonging. Maximum values of equivalent dose rates for viscera and, first of all, liver exceed such for the whole body of fishes. But they are significantly lower than the dose rate limit recommended by IAEA for the protection of aquatic organisms from ionizing radiation.     

Invaders Ctenophores Mnemiopsis leidyi (A. Agassiz) and Beroe ovata Mayer 1912, and Their Influence on the Pelagic Ecosystem of Northeastern Black Sea

We analyzed the state of pelagic ecosystem of northeastern Black Sea affected by invasion of a new settler Beroe ovata in 1999–2001. Development of B. ovata considerably decreased the population of another invader, Mnemiopsis leidyi, that deformed the Black Sea ecosystem for over a decade. Reduction of M. leidyi population limited its influence on the ecosystem and, consequently, we observed recovering of the main components of the Black Sea pelagic ecosystem—zooplankton and fish as well as their eggs and larvae. The relationships between annual and seasonal variability of the population development and size of the both invaders M. leidyi and B. ovata are discussed.     

Polonium-210 Absorption in Rats: Effects of Biological Modification

CALCULATIONS of maximum permissible body burdens of polonium-210 for radiation workers and the general public made by the International Commission on Radiological Protection (ICRP) assume 0.06 as the fraction going from the gastrointestinal tract to blood¹. This estimate is based on the work of Delia Rosa et al.², in which freshly neutralized polonium chloride solution was given orally to rats by stomach intubation (gavage). Excretion functions and tissue retention were measured and used to calculate the transfer of polonium across the gut. Hill³ and Kauranen and Miettinen⁴, who studied the transfer of Po along the lichen-reindeer or caribou-man food chain, suggested that the ²¹⁰Po found in the soft tissues of herbivores may be organically bound and therefore readily available to humans. Their data indicated that the ²¹⁰Po ingested from reindeer meat was from five to twenty-five times more available than predicted from the transfer values adopted by the ICRP. Experiments reported here indicate that polonium secreted in the milk of a goat which had been given an acute oral dose of PoO₂ is absorbed across the gut of rats in concentrations approximately twenty times greater than that absorbed when rats are fed PoO₂ or PoCl₄ in drinking water. These results are at least partial verification of the greater availability of ²¹⁰Po through biological modification as estimated by Hill.     

Comparative role of salps and other zooplankton in the cycling and transport of selected elements and natural radionuclides in Mediterranean waters

Salps, salp fecal pellets and other zooplankton species were analyzed for a suite of elements and natural radionuclides to assess their role in the biogeochemical cycling of nuclides in oceanic waters. The nuclide/Al ratios in organisms normalized to the same ratio in crustal rock indicated that Ca, Sr, Zn, Cu, U,²¹⁰Po, and²¹⁰Pb are enriched in the organisms. The concentrations of Fe, Al, Th isotopes and²¹⁰Pb in salps and fecal pellets were about an order of magnitude higher than those in salps, whereas Ca, Cu, Zn, Mn and Po were higher by factors of about 2–5. Fluxes via salp defecation were higher than those which have been measured in crustacean zooplankton species, a result primarily due to the high defecation rates characteristic of salps. High nuclide levels in salp fecal pellets coupled with high defecation rates and presumed high salp biomass in many areas underscore the importance of these indiscriminate filter feeders in packaging and transporting to depth particulate-associated nuclides in surface waters.     

Length–weight and length–length relationships for four shad species along the western Black Sea coast of Turkey

This study investigates length–weight and length–length relationships of four shad species (Alosa caspia caspia, Alosa immaculata, Alosa maeotica, Alosa tanaica) captured in the western Black Sea coast of Turkey. A total of 686 specimens, 355 females and 331 males, were caught by gill net, trammel net and longline from 2006 through 2007 along the western Black Sea coast of Turkey. The relationships of total length (TL), fork length (FL) and standard length (SL) are presented for inhabiting in the Black Sea four shad species and the relationships between total length (TL) and body weight (BW) from the two localities, Sile and Karasu in the western Black Sea coast of Turkey. The Length–weight relationships generally indicated positive allometric growth in Alosa species for both males and females and an isometric growth for A. immaculata females. The coefficient b ranged from a minimum 2.97 for females of A. immaculata to a maximum 3.75 for both sexes A. c. caspia. Results indicated that the length–length relationship between the three length measurements were highly correlated (r² > 0.99, P < 0.001).     

Natural variation in <Superscript>210</Superscript>Po and <Superscript>210</Superscript>Pb activity concentrations in the urine of Finnish population groups

A study to determine activity concentrations of ²¹⁰Pb and ²¹⁰Po in the urine of certain Finnish population groups was conducted, to investigate the variation in natural background level of urinary excretion. The study participants were divided into three groups mainly based on their diet. The first group comprised recreational fishermen and the second group represented people consuming more reindeer meat than an average Finn, while people using drinking water with very high activity concentrations of ²¹⁰Po were selected for the third group. The fourth group was a control group. The mean urinary excretion of ²¹⁰Po in groups 1 and 2 was 73 and 100 mBq d⁻¹, respectively. These values were higher than the value of the control group (20 mBq d⁻¹) and the mean values reported in the literature. The mean daily urinary excretion of ²¹⁰Pb in groups 1 and 2, 70 and 52 mBq d⁻¹, was also slightly higher than that in the control group (32 mBq d⁻¹). In contrast, the excretion rates of both ²¹⁰Po and ²¹⁰Pb for the members of group 3 were one to two orders of magnitude higher than those reported in the literature. This was clearly due to the elevated levels of natural radionuclides in their drinking water. The present study demonstrates the importance of possessing good knowledge of the background levels, in order to allow the determination of the additional exposure due, for example, to the malevolent use of radiation.     

Identifying resuspended particles using isotope ratios

Three simple methods were developed to estimate the proportion of particles in lake water derived from resuspended material. These techniques use the different distributions of long and short-lived radioisotopes sorbed onto particles and were tested in the three basins of Lake Erie using ⁷Be, ¹³⁷Cs and ²¹⁰Po/²¹⁰Pb.While the concentration of ²¹⁰Po on particles did not vary significantly in the lake, resuspended particles were characterized by high concentrations of ¹³⁷Cs and low concentrations of ⁷Be. The distribution of these radioisotopes is consistent with a simple mixing model in which the fraction of particles in the lake water derived from resuspension ranged from 8% to about 100%. Higher concentrations of resuspended particles were found in deeper samples from the nepheloid layer and in the shallow western basin where thermal stratification was very weak.     

Aggressive behavior as a mechanism of spatial differentiation of juvenile salmonid fishes (based on Black Sea brown trout Salmo trutta labrax (salmonidae))

Aggressive behavior of hatchery-reared juvenile Black Sea brown trout Salmo trutta labrax at the age of 5.5–6.0 months is investigated. Shortage of suitable territory leads to the separation of the fish into two spatial groups: demersal and pelagic. During the process of spatial differentiation of the fish, the individuals that have not selected permanent habitats (demersal or pelagic) are characterized by the highest aggression level. The duration of the formation of stable spatial differentiation of the fish depends on the stocking density. At a low stocking density (10–45 fish/m²), spatial differentiation is established by the beginning of the second day after the transfer of the fish to new conditions; at a high stocking density (182 fish/m²), it is established approximately by the seventh day. Following the establishment of the (secondary) spatial groups, aggressive acts are registered mainly between the individuals from the same spatial group. A role of aggressive behavior in intrapopulation differentiation of brown trout is discussed.     

Description of two new species of the genus Gobio (Teleostei: Cyprinidae) from the Black Sea coast of Turkey

Thesystematics of the genus Gobio, especially of the populations on the southern Black Sea coast, seems to be still far from being resolved. Seven species were rec-orded from the northern Black Sea coast while three species were recognized from the southern Black Sea coast. We examined in total 43 specimens from K?z?l?rmak River (southern Black Sea basin), 80 specimens from Çoruh River (the Western Cau-casus of the Black Sea basin), 14 specimens from Rioni River (the Western Caucasus of the Black Sea basin), and 6 specimens from Kherota and Shakhe Rivers (the Western Caucasus of the Black Sea basin). Based on an analysis of 32 metric and 5 meristic data as well as the number of vertebrae, we concluded that the K?z?l?rmak and Coruh populations are two distinct, unnamed species, and we describe them here as Gobio kizilirmakensis from the K?z?l?rmak River and G. artvinicus from the Çoruh River.

http://www.zoobank.org/urn:urn:lsid:zoobank.org:pub:1ED54FB1-588F-4412-B376-4BE4E4516EB1     

Competitive advantage of the invasive copepod Oithona davisae over the indigenous copepod Oithona nana in the Marmara Sea and Golden Horn Estuary

Around 2010, the alien copepod Oithona davisae was introduced to the Marmara Sea and Golden Horn Estuary to live alongside the native species, Oithona nana. By October 2015, the population number, including nauplii, of the introduced species (213,600 ind m^?3) was higher than that of the native species (54,900 ind m^?3) and close to that of O. davisae in Sevastopol Bay of the Black Sea (342,000 ind m^?3) where it appeared 14 years ago. A high percentage of O. davisae females with ovisacs (up to 30% of total female number) carrying up to 15.1 ± 2.1 eggs in the sac and the predominance of nauplii in the population (up to 95% of the total population number) indicate that this alien copepod has become a permanent component of the Marmara Sea and Golden Horn Estuary ecosystem. Our experiments showed that in comparison with widely euryhaline O. davisae, O. nana is a stenohaline species. It has a salinity tolerance in the range of 13–27 psu and, in spite of having a larger body, a lower body density (1.037 ± 0.007 g cm^?3) and sinking speed. Carbon-specific respiration rates of both species were close (0.32–0.38 μL O₂ μgC^?1 day^?1) and similar to that of O. davisae from the Black Sea during this period but the frequency and speed of routine jumps, and the maximum escape reaction speed (up to 23.3 ± 1.7 cm s^?1) in O. davisae from the Marmara Sea were significantly higher. This indicates the higher adaptive potential of O. davisae in this situation compared to that of O. nana.     

Distribution of Sprattus sprattus phalericus (Risso, 1827) and zooplankton near the Black Sea redoxcline

Understanding what environmental drivers influence marine predator–prey relationships can be key to managing and protecting ecosystems, especially in the face of future climate change risks. This is especially important in environments such as the Black Sea, where strong biogeochemical gradients can drive marine habitat partitioning and ecological interactions. We used underwater video recordings in the north-eastern Black Sea in November 2013 to observe the distribution and behaviour of the Black Sea sprat (Sprattus sprattus phalericus, Risso 1827) and its zooplankton prey. Video recordings have shown that the Black Sea sprat S. sprattus phalericus tolerates severely hypoxic waters near the redoxcline. The school was distributed in the 33–96 m layer [oxygen concentration (O₂) 277–84 μmol L⁻¹]. Some individuals were observed to leave the school and descended 20 m deeper for foraging on copepods in the 119–123 m layer (O₂ 12–10 μmol L⁻¹). Zooplankton appeared concentrated on the upper boundary of the suboxic zone (O₂ < 10 μmol L⁻¹). No zooplankton were observed below O₂ 6–7 μmol L⁻¹ (128 m). Understanding the ability of this species to tolerate low oxygen waters is crucial to predicting future responses to natural and anthropogenic changes in hypoxia.     

Contrasting multispecies patterns in larval fish production trace inter-annual variability in oceanographic conditions over the N.E. Aegean Sea continental shelf (Eastern Mediterranean)

The response of larval fish communities of the northeastern Aegean Sea (NEA) to interannual environmental changes is analyzed using data from four ichthyoplankton surveys covering the NEA continental shelf during June 1993, 1994, 1995, and 1996. Waters were significantly cooler, less saline and richer in zooplankton in 1993 and 1996 (‘cold’ years) than in 1994 and 1995 (‘warm’ years). A comparison of monthly SST series (1993–1997) between the NEA, the Marmara Sea, and the Western Black Sea revealed high correlations and similar trend components among these areas implying that oceanographic conditions over the NEA (and observed inter-annual differences) were most likely dominated by the properties and relative amount of Black Sea water inflow in the NEA. The relative composition of the larval fish community was significantly related to the ‘cold/warm’ regime and larval diversity was higher during the warm years. Larvae of the small-sized pelagic species, such as anchovy (Engraulis encrasicolus), and most mesopelagic fishes were relatively more abundant during the cold, zooplankton-rich years. Larvae of the middle-sized pelagics (Sardinella aurita, Scomber japonicus, Trachurus mediterraneaus, Auxis rochei) and certain benthopelagic species exhibited an opposite trend, i.e., they were more abundant during the warm years or absent during the cold years. Most of these species are known to be typical summer spawners (e.g., Serranus cabrilla, Lisa saliens, Trachinus draco, and Symphurus nigrescens). Co-variation in larval fish production might be indicative of similar responses among species to changing physical and/or trophic regimes.     

Some biological characteristics of early larvae Dacodraco hunteri (Notothenioidei: Channichthyidae) in the western Ross Sea

Ichtyoplankton surveys were carried out in the western Ross Sea by the R/V Italica in the austral summer 1996 and 1997–1998 to study species composition and spatial distribution of larval stages of fish. One of the most abundant icefish caught was Dacodraco hunteri, a poorly known channichthyid inhabiting the high-Antarctic Zone. Based on 382 yolk-sac larvae and 13 preflexion larvae, the study was focused to estimate spatial distribution and abundance, as well as diet and growth rate. The pigmentation pattern and some morphometric measurements were also recorded for comparative purposes. The specimens were caught in relatively restricted areas located in Terra Nova Bay and north of the Ross Ice Shelf on the Challenger and Joides Basins. The standardized abundance of early larvae ranged between 0.03 and 1.72 individuals 10⁻³ m³ in 1996 and 0.16–4.53 individuals 10⁻³ m³ in 1997–1998, respectively. Fitting a linear model to the mean length increase in larvae collected in subsequent catch dates, the growth rate was estimated to be approximately 0.11 mm/day. Based on back calculation of growth rate and presumed hatch size of 11 mm, larval hatching probably took place in mid-December. Diet of preflexion larvae consisted exclusively of larvae of the pelagic nototheniid Pleuragramma antarcticum, a key species of the high-Antarctic pelagic food web. Hence, D. hunteri probably plays a more important role than previously thought in the pelagic community of the Ross Sea.     

210Po Activity and Concentrations of Selected Trace Elements (As, Cd, Cu, Hg, Pb, Zn) in the Muscle Tissue of Tunas Thunnus albacares and Katsuwonus pelamis from the Eastern Pacific Ocean

Daily mineral intake (DMI) of Cu and Zn, percentage weekly intake (PWI) of As, Cd, Hg, Pb, and doses of ²¹⁰Po were estimated by using their elemental concentration in muscle of two tuna species and the average tuna consumption in Mexico. Skipjack tuna Katsuwonus pelamis had significantly (p?<?0.05) higher levels of As (1.38???g?g^?1 dw) and Cu (1.85???g?g^?1 dw) than yellowfin tuna Thunnus albacares, whereas Pb concentrations (0.18???g?g^?1 dw) were significantly (p?<?0.05) higher in T. albacares. The sequence of elemental concentrations in both species was Zn?>?Cu?>?As?>?Hg?>?Pb?>?Cd. In T. albacares, concentrations of Cd and Pb in muscle tissue were positively correlated (p?<?0.05) with weight of specimens, while Cu was negatively correlated. DMI values were below 10?%. PWI figures (<2?%) are not potentially harmful to human health. ²¹⁰Po concentration in T. albacares and K. pelamis accounts for 13.5 to 89.7?% of the median individual annual dose (7.1???Sv) from consumption of marine fish and shellfish for the world population.     

Fish biology and fisheries ecology of the Salton Sea, California

Studies of the fisheries ecology and fish biology of the Salton Sea, California, were conducted in 1999 and 2000 using 50 m gill nets in river, nearshore, pelagic, and estuarine areas. Total lengths and weights were measured for all fish captured, and sub-samples were dissected for gonad weights and aging. Ten fish species were captured of which a hybrid tilapia (Oreochromis mossambicusx O. urolepis hornorum) was dominant by number and weight. Nearshore and estuarine areas had highest catch rates (over 11 kg h^–1 net^–1 for tilapia). Rivers were richest in the number of species (6 of 10 species were exclusively riverine), but lowest in fish abundance. Orangemouth corvina (Cynoscion xanthulus), bairdiella (Bairdiella icistia), sargo (Anisotremus davidsoni), and tilapia grew faster, but had shorter life spans than conspecifics elsewhere and Salton Sea conspecifics of 50 years ago. Reproduction occurred mostly in the nearshore and estuarine areas. Onset of reproduction of bairdiella and sargo was in the spring and extended through the beginning of summer. Reproduction of orangemouth corvina started in the summer and of tilapia in the spring. Reproduction of orangemouth corvina and tilapia extended through the fall. Gender ratios of tilapia were skewed toward males in all areas, except the rivers, where females predominated. All four species aggregated along the nearshore and estuarine areas in the summer when dissolved oxygen in the pelagic area was limited. Any restoration alternative for the Salton Sea should consider areas close to shore as primary areas for fish reproduction and survival.     

Isolated population of the Middle Eastern Phoenicolacerta laevis from the Georgian Black Sea Coast,and its genetic closeness to populations from southern Turkey

The Lebanon Lizard (Phoenicolacerta laevis) occurs on the Levantine coast and scattered populations are found in isolated coastal habitats along the southern and south-western coast of Turkey. We found an isolated but dense population of this species at and around the castle of Anaklia on Georgia’s Black Sea Coast, near the mouth of the river Enguri. The analysis of mitochondrial cytochrome b sequence suggests closeness of this population to the populations in the provinces of Kahramanmara?, Adana and Içel in southern Turkey, rather than to those in Lebanon and Israel. It is thought that the species was introduced from a Turkish region to Anaklia, which was an important trade location at the eastern Black Sea coast until the late 18^th century. This is the first established location of this species outside the eastern Mediterranean area. Climate and competition with rock lizards of the genus Darevskia are the most likely reasons preventing expansion of the species into the neighboring areas of Western Georgia.     

Sterols from two Black Sea sponges (Haliclona Sp.)

The sterol composition of two sponges, Haliclona flavescens and Haliclona cinerea, from the Black Sea was investigated. Sterol composition in the two species is similar and both sponges actively transform dietary sterols into stanols and further to Δ⁷-sterols. Short side chain sterols of androstane and pregnane type were discovered in one sample. The composition of steryl esters and the taxonomic position of the two Haliclona species are discussed.     

The problem of invaders in the Caspian Sea in the context of the findings of new zoo- and phytoplankton species from the Black Sea

In April 2004, an expedition to the Caspian Sea discovered the species in the Middle Caspian not previously described in this sea. These species preliminary identified as Oithona similis Claus 1963, Sagitta setosa Muller 1847, and Calanus euxinus (Hulsemann) are the main representatives of edible plankton of the Black Sea; most likely they were introduced into the Caspian Sea with ballast waters of ships passing through the Volga-Don Canal. At present, it is difficult to say if these species will be established in the Caspian Sea; if so, they will clearly become a valuable food resource for planktophagous fish in the Caspian Sea. In addition, we discovered two diatom species typical for the Black Sea phytoplankton, Pseudo-nitzschia seriata (Cleve) H. Peragallo and M. Peragallo and Cerataulina pelagica (Cleve) Hendey which invaded the Caspian Sea in recent years. Pseudo-nitzschia seriata synthesizes a toxin (domoic acid) and can become harmful for the basin in the case of mass bloom. We discuss the problem of spontaneous invasion of alien species from the Black Sea and their effect on the Caspian ecosystem in the context of these findings.Translated from Izvestiya Akademii Nauk, Seriya Biologicheskaya, No. 1, 2005, pp. 78–87.Original Russian Text Copyright © 2005 by Shiganova, Musaeva, Pautova, Bulgakova.