Stratification of microbial assemblages in Mono Lake, California, and response to a mixing event

Vertical profiles of microbial assemblages from samples of Mono Lake water collected in July 1994 and in April and July 1995 were obtained by analyzing DNA via the polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) of 16S ribosomal RNA (rRNA) genes. The microbial assemblage was vertically stratified and distributions of individual ribotypes were coherent with temperature, salinity, irradiance and dissolved oxygen distributions at the beginning of the study in July of 1994. The lake mixed completely during the winter of 1994–1995 and was beginning to stratify thermally by April 1995. Water column gradients were weak and oxygen was depleted at depth. The microbial assemblage was uniformly distributed throughout the water column except at 20 m, where one band dominated. The microbial assemblage was vertically stratified again by July 1995. Partial sequences (134–160 bp, except one of 83 bp) obtained from DGGE bands revealed affinities to known organisms, but only one potentially exact match was found. With a few exceptions, the same ribotypes were present on all sampling dates; there was no evidence for a marked seasonal succession in microbial community composition, despite the dramatic changes in limnological conditions that accompanied the winter overturn. A band that was ubiquitous in samples from the oxycline and hypolimnion in July of both years was found throughout the water column in April. This sequence could be attributed to the chloroplast rRNA gene of an unusual phytoplankter, the green alga Picocystis salinarum.     

Photosynthetic activity of phytoplankton and its relation to environmental factors in hypersaline Mono Lake,California

The photosynthetic activity of phytoplankton in hypersaline Mono Lake, California was measured over the three year period, 1983–1985. The maximum chlorophyll-specific rate of carbon uptake (P_m ^B) and the light-limited slope (alpha) were derived from laboratory measurements of photosynthesis vs. irradiance (P-I) relationships. Annual estimates of primary production were 340–540 g C m^-2 yr^-1. Production was two to three times higher during the spring of 1983 than in the springs of 1984 and 1985; higher standing biomass of algae occurred in 1983. While P_m ^B rates followed water temperatures and varied over 40-fold over the year, integral primary production varied less since periods of high P_m ^B occurred when algal biomass was low. Sixty-eight percent of the seasonal variation in the P_m ^B was explained by a regression on temperature (53%), chlorophyll a (12%), and the carbon:chlorophyll a ratio (3%). Light-saturated and light-limited rates of photosynthesis generally covaried, evidenced by the strong seasonal correlation between P_m ^B and alpha. Sixty-one percent of variation in alpha was explained by a regression on P_m ^B, temperature, grazing, water column stability, and self-shading. There was no correlation of carbon uptake with ambient levels of inorganic nitrogen. The regression coefficient of the dependence of P_m ^B on the seasonal temperature trend was much larger than that determined from individual samples incubated at several different temperatures; this indicates that uptake is limited by more than low temperatures in the spring. Regression equations including only temperature, chlorophyll and depth were sufficient to estimate patterns of seasonal and year to year variation in integral primary productivity.     

Airborne remote sensing of chlorophyll distributions in Mono Lake, California

As part of a long-term investigation of seasonal and interannual variations of plankton in Mono Lake (California), we developed a methodology using airborne imaging spectrometry to synoptically measure chlorophyll concentrations. Images of Mono Lake were acquired with NASA's Airborne Visible and Infrared Imaging Spectrometer (AVIRIS) and were atmospherically corrected by applying a version of the radiative transfer model MODTRAN. Using a predictive equation for calculation of chlorophyll based on a band ratio of remote sensing reflectances (R_{{ rs}}; R_{{ rs}} 490 nm/R_{{ rs}} 550 nm), spatial distributions of chlorophyll throughout the lake were determined; broad east to west gradients in chlorophyll and gyres are evident.     

Nitrogen limitation and particulate elemental ratios of seston in hypersaline Mono Lake, California, U.S.A.

Particulate elemental ratios (C:N, N:P and C:Chl a) of seston in hypersaline (70–90 g kg^–1) Mono Lake, California, were examined over an 11-year period (1990–2000) which included the onset and persistence of a 5-year period of persistent chemical stratification. Following the onset of meromixis in mid-1995, phytoplankton and dissolved inorganic nitrogen were substantially reduced with the absence of a winter period of holomixis. C:N, N:P and C:Chl a ratios ranged from 5 to 18 mol mol^–1, 2 to 19 mol mol^–1 and 25 to 150 g g^–1, respectively, and had regular seasonal patterns. Deviations from those expected of nutrient-replete phytoplankton indicated strong nutrient limitation in the summer and roughly balanced growth during the winter prior to the onset of meromixis. Following the onset of meromixis, winter ratios were also indicative of modest nutrient limitation. A 3-year trend in C:N and N:P ratios toward more balanced growth beginning in 1998 suggest the impacts of meromixis weakened due to increased upward fluxes of ammonium associated with weakening stratification and entrainment of ammonium-rich monimolimnetic water. A series of nutrient enrichment experiments with natural assemblages of Mono Lake phytoplankton conducted during the onset of a previous episode of meromixis (1982–1986) confirm the nitrogen will limit phytoplankton before phosphorus or other micronutrients. Particulate ratios of a summer natural assemblage of phytoplankton collected under nitrogen-depleted conditions measured initially, following enrichment, and then after return to a nitrogen-depleted condition followed those expected based on Redfield ratios and laboratory studies.     

First survey of fungi in hypersaline soil and water of Mono Lake area (California)

Mono Lake is a closed lake located in central California, east of the Sierra Nevada mountains. It contains dissolved carbonates, sulfates and chlorides at high concentrations. Due to its high salinity, Mono Lake was sometimes compared to the Dead Sea. However, it appears that Mono Lake water and vicinity abound with life. In this work, the fungal flora living in this extreme ecosystem was studied for the first time. Soil, tufa, water and sediment samples were also analyzed for their mineral and salt composition. Results showed that water was particularly rich in sodium, potassium, phosphorus and boron. Soil and sediments contained very high levels of calcium and magnesium, but also barium, boron and strontium. Sodium, phosphorus and iron levels varied in a large extent from one to another sample. Neutral to very alkaline pH were recorded. Water samples were found sterile in the conditions chosen for fungi isolation, while sediment, soil and tufa samples led to the isolation of a total of 67 fungal species (from 23 samples), belonging to various taxonomic groups. From our results no clear effects of the chemical parameters of the samples were observed on fungal life apart from the pH. The methods chosen did not allow the isolation of extremely halotolerant species. We isolated in this work a series of ubiquitous species, suggesting that a selection of resistant and/or adaptable strains of some common species could have occurred. Depending on the medium and the temperature of isolation, it can be hypothesized that some species were present as dormant structures, while some others, isolated at pH 8 on a medium enriched in Na and Ca, could be in a growing form adapted to alkaline and saline conditions. This work contributes to a better knowledge of the mycobiota present in the Mono Lake's ecosystem.     

Chemical stratification and partial meromixis in reservoirs in Tasmania

During the first summer after impoundment, chemical stratification occurred in four deep, steep-sided reservoirs of the Pieman River Power Development, Tasmania, under the influence of thermal stratification and anoxic hypolimnia caused by decaying vegetation in the flooded river valleys. Marked increases occurred in temperature, conductivity, pH, and in concentrations of dissolved iron, manganese, calcium, magnesium and bicarbonate in the sulphuretted, reducing, waters which accumulated as monimolimnetic pools adjacent to the dams. This partial, incipient meromixis persisted only in Lake Murchison, where a shallow monimolimnetic pool remained three years later. In the other reservoirs of the Pieman scheme it decayed after one or two years. Reservoir morphometry, degree of shelter, nature of major inflows, and alignment with respect to prevailing winds, are primary factors determining the persistence or eventual decay of chemical stratification in the respective impoundments. In Lake Barrington, another meromictic Tasmanian reservoir, the initial chemical gradient decayed and virtually disappeared, but was reestablished with greater severity than on any previous occasion. The severity of partial meromixis may wax and wane in relation to seasonal or longer-term meteorological events.     

Limnological effects of anthropogenic desiccation of a large, saline lake, Walker Lake, Nevada

Walker Lake is a monomictic, nitrogen-limited, terminal lake located in western Nevada. It is one of only eight large (Area>100 km², Z _{{ mean}}>15 m) saline lakes of moderate salinity (3–20 g l^–1) worldwide, and one of the few to support an endemic trout fishery (Oncorhynchus clarki henshawi). As a result of anthropogenic desiccation, between 1882 and 1996 the lake's volume has dropped from 11.1 to 2.7 km³ and salinity has increased from 2.6 to 12–13 g l^–1. This study, conducted between 1992 and 1998, examined the effects of desiccation on the limnology of the lake. Increases in salinity over the past two decades caused the extinction of two zooplankton species, Ceriodaphnia quadrangula and Acanthocyclops vernalis. Recent increases in salinity have not negatively affected the lake's dominant phytoplankton species, the filamentous blue-green algae Nodularia spumigena. In 1994 high salinity levels (14–15 g l^–1) caused a decrease in tui chub minnow populations, the main source of food for Lahontan cutthroat trout, and a subsequent decrease in the health of stocked trout. Lake shrinkage has resulted in hypolimnetic anoxia and hypolimnetic accumulation of ammonia (800–2000 g-N l^–1) and sulfide (15 mg l^–1) to levels toxic to trout. Internal loading of ammonia via hypolimnetic entrainment during summer wind mixing (170 Mg-N during a single event), vertical diffusion (225–500 Mg-N year^–1), and fall destratification (540–740 Mg-N year^–1) exceeds external nitrogen loading (<25 Mg-N year^–1). Increasing salinity in combination with factors related to hypolimnetic anoxia have stressed trout populations and caused a decline in trout size and longevity. If desiccation continues unabated, the lake will be too saline (>15–16 g l^–1) to support trout and chub fisheries in 20 years, and in 50–60 years the lake will reach hydrologic equilibrium at a volume of 1.0 km³ and a salinity of 34 g l^–1.     

Manipulation of Whole-Lake Ecosystems and Long-Term Limnological Observations in the Brandenburg — Mecklenburg Lake District,Germany

An accompanying technical use of ecological effects from pelagic food-web interactions (biofiltration) or from sediment (nutrient remobilization) can speed up recovery of lake ecosystems and can make restoration programs more effective after external load reductions. At present the comprehensive use of multiple ecotechnological controls for water quality is limited because our knowledge of the many complex interactions, indirect effects and above all the long-term effects of such operations is insufficient. Beginning in the 1960s we started long-term limnological analyses of the trophic interactions between community structure and the flow of matter under “manipulated” conditions in whole-lake experiments at Lake Stechlin (manipulated water circulation and waste heat), Lake Haussee (biomanipulation) and Lake Fuchskuhle (lake-dividing). This paper summarises changes in abiotic and biotic structures and functions of the manipulated lake ecosystems and discusses the possibilities and limitations of “whole-lake” experiments.     

Size-fractionated phytoplankton biomass and its implications for the dynamics of an oligotrophic tropical lake

1. Size-fractionated phytoplankton biomass was examined in relation to the hydrodynamics of tropical Lake Alchichica from 1999 to 2002.
2. Alchichica is a warm monomictic lake, in which mixing takes place from late December to early March. The lake is oligotrophic (mean total chlorophyll- a concentration 4.2 ± 4.2  μ g L⁻¹) and its phytoplankton biomass is dominated (72.3 ± 16.4%) by large individuals (>2  μ m). The degree of dominance of the large size class (nano- and microplankton) over the small size class (picoplankton) throughout the year is mainly determined by the availability of silicate and the Si/N ratio in the hypolimnion prior to the mixing period.
3. This is the first record of an oligotrophic tropical lake dominated by large size fractions of phytoplankton. Because of this dominance, the fate of most primary productivity is rapid sedimentation to the bottom followed by decomposition that promotes an anoxic hypolimnion.
4. Our findings in tropical Lake Alchichica challenge the idea that oligotrophic waters are dominated by small phytoplankton, as has been well established for the oligotrophic ocean and temperate lakes.     

Autumnal mixing in Mahoney Lake,British Columbia

Salinity, water temperature and meteorlogical measurements were made over a 5 month period (June–Oct.) at Mahoney Lake, British Columbia to study autumnal mixing. The measurements were made during a time when the lake had been well stratified by a much larger than average runoff the previous spring. The potential energy of stratification decreased from 50 to 24 MJ, in the top 8 m of the water column, from mid August to mid October. Analysis of the energy available from wind shear on the water surface and from penetrative convection during the autumn cooling period was made. Winds were found to be weak (av. 2.17 m s ^–1) at Mahoney Lake, and their average contribution to mixing energy during the study period was less than 30%. Penetrative convection from thermals descending from the cool surface contributed an average of 2.21 J m^–2 d^–1 to mixing which represented 72 % of the energy available. An efficiency factor of 0.20 for the penetrative convection energy, larger than values previously reported in the literature, was found to fit the measured loss of potential energy of stratification during the period.     

The effect of evapoconcentration on dissolved organic carbon concentration and quality in lakes of SW Greenland

1. Dissolved organic carbon (DOC) concentration was determined for a range of lakes of varying conductivity (30–4000 μS cm⁻¹) in the low Arctic of SW Greenland. DOC concentration range from <1 to >100 mg C L⁻¹, occasionally approaching 200 mg C L⁻¹ in meromictic, oligosaline lakes. DOC concentration was strongly related to [log₁₀] conductivity and total nitrogen. 2. Peak DOC concentrations (>80 mg L⁻¹) occur in lakes located approximately 50 km from the present ice sheet margin, a zone of low effective precipitation; evaporative concentration is the first‐order control on DOC concentration. Lakes at the coast and closer to the ice margin had lower DOC concentrations (<20 mg C L⁻¹). Local factors, notably the presence or absence of an outflow and catchment morphometry, resulted in considerable variability in concentration (20–100 mg C L⁻¹) within the area of maximum concentration around 51°W. 3. Despite their high DOC concentration, these lakes are essentially colourless. Dissolved organic matter (DOM) absorption (a₃₇₅) was low in most lakes (<10 m⁻¹) with maximum values (approximately 20 m⁻¹) occurring in one humic‐stained lake in the area. Absorption values corrected for DOC concentration () were very low (<0.6 m² g⁻¹ C) for all lakes apart from those at the coast, perhaps reflecting greater allochthonous inputs at these sites. 4. S, the spectral slope coefficient, ranged from 16 to 27 μm⁻¹ and was weakly correlated with DOC concentration. Both a₃₇₅ and S showed similar distribution patterns along the sampling gradient as did DOC, with maximum values at approximately 51°W. High and low S may indicate fresher, more rapidly flushed, systems with less degraded DOM or greater inputs from their catchments. 5. The lakes closer to the head of the fjord with higher conductivity, had low (<0.2 m² g⁻¹ C) and high S (>21 μm⁻¹) and this may reflect increasingly longer lake water residence times, greater DOM age and photochemical degradation.     

Distribution and abundance of the alkali fly (Ephydra hians) Say at Mono Lake,California (USA) in relation to physical habitat

The distribution and abundance of larval, pupal, and adult stages of the alkali fly Ephydra hians Say were examined in relation to location, benthic substrate type, and shoreline features at Mono Lake. Generation time was calculated as a degree-day model for development time at different temperatures, and compared to the thermal environment of the lake at different depths.Larvae and pupae have a contagious distribution and occur in greatest abundance in benthic habitats containing tufa (a porous limestone deposit), and in least abundance on sand or sand/mud substrates. Numbers increase with increasing area of tufa present in a sample, but not on other rocky substrates (alluvial gravel/cobble or cemented sand). Standing stock densities are greatest at locations around the lake containing a mixture of tufa deposits, detrital mud sediments, and submerged vegetation. Shoreline adult abundance is also greatest in areas adjacent to tufa. The shore fly (ephydrid) community varies in composition among different shoreline habitats and shows a zonation with distance from shore.The duration of pupation (from pupa formation to adult eclosion) becomes shorter as temperature increases. The temperature dependence of pupa development time is not linear and results in prolonged time requirements to complete development at temperatures below 20 °C. About 700 to 1000 degree-days are required to complete a generation. Degree-days of time available in nature declines by 10 to 50% at depths of 5 and 10 metres relative to surface waters (depending on the extent of mixing), resulting in fewer possible generations. Essentially no growth would be expected at 15 m, where temperature seldom exceeds the developmental minimum. It is concluded that reduced substrate availability and low temperatures may limit productivity of the alkali fly at increasing depths in Mono Lake.     

Artemia monica cyst production and recruitment in Mono Lake,California, USA

Annual egg production was determined for Artemia monica in Mono Lake, California, from 1983 to 1987. Annual oviparous (overwintering cyst) production was 3 and 7 million cysts m^–2 yr^–1 in 1986 and 1987, respectively, as measured by in situ sediment traps. Cyst production for the entire five year period was calculated using Artemia census data and inter-brood duration derived from mixolimnetic temperature. These estimates ranged from 2 to 5 million cysts m^–2 yr^–1. This method underestimated annual production by 30%, when compared to estimates using sediment traps. Cyst production was similar during 1983–1986 and showed a significant increase in 1987, which was due primarily to a larger reproductive population later in the year. Recruitment into the adult populations of the following spring ranged between 1.4 to 3.2%. Overall abundance of this generation reflected the patterns in annual cyst production. Compensatory effects must operate on the second generation of each year, since summer populations were similar in all years despite differences in cyst production.     

Re-appearance of rotifers in hypersaline Mono Lake, California, during a period of rising lake levels and decreasing salinity

The surface elevation of Mono Lake, California, rose 2 m and mixed-layer salinities declined about 5 g kg^–1 during the 3 years (1995–1997) following the decision to restrict water diversions out of the Mono Basin. Abundant (18000 m^–2) Hexarthra jenkinae de Beauchamp were noted in pelagic samples in October 1997 after three decades of absence or very low abundance. Abundance subsequently increased to 100000 m^–2 in December 1997 before declining to low numbers through 1998 and 1999. The re-appearance of Branchionus plicatilis Müller in pelagic samples occurred in September 1998. B. plicatilis areal abundance increased to 15000 m^–2 in October–December of both 1998 and 1999 but was low throughout the rest of the year. Both rotifers were noted in nearshore ponds, but were only abundant in those with salinities below 53 g kg^–1. During 1998–1999 when the salinities of the upper water column were 73–75 g kg^–1, less saline shoreline habitats may have been seeding the offshore rotifer populations.     

Physical and Chemical Limnology of a Subsaline Athalassic Lake in West Greenland

Physical and chemical profiles of a shallow (c. 12-m-deep) subsaline (total dissolved solids 2.3-2.8 g l^–1) closed-basin lake in the continental area of southwestern Greenland are described for the first time. Watercolumn data for every 5th consecutive day between April 20 and October 6, 2001, and continuous recordings of lake water level and meteorological conditions are used to infer controls on contemporary lake functioning, sediment formation and climate-lake interactions. Limnological observations demonstrate the importance of lake-ice formation and its role in haline convection and the development of meromixis. Observed lake cycling suggest that the lake at present is in a state of near-meromixis where stagnant bottom waters de-stratify through deep penetration of weak haline convective cells by the end of June. From this study, the primary reasons the shallow Greenlandic low salinity lakes develop meromixis are:(i) lack of an outflow (ii) meltwater dilution and chemical stratification of surface waters, (iii) insubstantial wind mixing, (iv) a weak winter thermohaline convective cell forced by cryoconcentration, and (v) biogeochemically enhanced solute concentrations near the sediment bed. Throughout the open water period the hydrological balance is dominated by evaporative losses. Lake surface water conductivities change from 2110 to 2890 S cm^–1 due to the combined effects of open water evaporation, meltwater dilution, diffusive exchanges over the seasonal pycnocline, and boundary mixing. Freeze-out of salts and resulting deep haline convection increase overall water column salinity during winter. Owing to deep convective mixing, plant nutrients are relatively high in the upper watercolumn with a dominant internal source of phosphorous. Extreme productivity pulses of phytoplankton are observed as soon as sub-ice radiation levels increase and directly after ice-out when sufficient wind mixing can support an intense monospecific diatom bloom of Diatoma spp. leading to the rapid depletion of dissolved silica.     

Consequences of redox conditions on the distribution of cations in a meromictic oligotrophic lake

The cations Ca, Mg, Zn, Na, K, Mn and Fe were measured during the year 1977 in the mixolimnion and in the monimolimnion of lake Pavin. The great difference between the residence time for Ca, Mg, Na, K (15 years) and for Mn and Fe (> 90 years) is due to the redox reactions in the chemocline. The overturn conditions and their influence on cation accumulation are studied.     

Vernal microstratification patterns in a meromictic saline lake: their causes and biological significance

Periodic high spring runoff, in addition to lake surface snow and ice melt, is shown to be a major cause of sharp secondary chemocline formation in a small (20 ha) lake arid and south-central British Columbia. Initially detected in 1982 at about 1 m and enhanced by high inflow of low salinity meltwater in spring 1983, the secondary chemocline gradually deepened and broke down over four subsequent years. Associated microstratification layers (major changes within a few cm of depth), exhibited very high temperatures (> 30 °C), and very high dissolved oxygen (> 200% saturation) as well as very low (close to 0% saturation) levels. Oxygen supersaturation resulted from photosynthetic production at the microstratification boundaries. In the springs of 1982 and 1983, formation of an anoxic layer between regions of high oxygen concentration, separated the phytoplankton and zooplankton communities into two layers above the primary chemocline. The several year persistence of the secondary chemoclines and associated interface processes (concentration of particulate organic matter, bacterial decomposition, nutrient regeneration, phytoplanktonic production) attest to their functional importance in this meromictic lake.     

Abundance and spatial distribution of Artemia salina in Lake Abert,Oregon

In 1981–1982 Abert Lake had an area of 200 km², with a mean depth of 2.5 m and a total dissolved salt concentration of 82 gl^-1. The spatial distribution and abundance of the brine shrimp, Artemia salina, were monitored for 1981–1982. In 1981 during the midsummer months, with sampling primarily in the eastern side of Abert Lake, brine shrimp populations showed peak densities of 2–4 ind. 1^-1. In 1982, peak abundance occurred in early July and ranged between 5–8 ind. 1^-1. Lakewide estimates of brine shrimp derived from 14 collecting stations and assuming a uniform distribution over the lake resulted in estimates of lakewide abundance of 3 × 10¹¹ adults with a total biomass of 7 × 10⁶ kg. The major algal species in the lake was a benthic filamentous green alga (Ctenocladus circinnatus).     

Physico-chemical characteristics and origin of hypersaline meromictic Lake Garrow in the Canadian high Arctic

Garrow Lake (75° 23 N; 96° 50 W), located 3 km from the southern tip of Little Cornwallis Island and 6.7 m above mean sea level, is a meromictic ecto-creno-cryogenic lake with an area of 418 ha and a maximum water depth of 49 m. The thermal stratification of this lake is mesothermic (heliothermic). Some of the solar energy that penetrates through the 2 m ice cover is stored for a long period of time in the upper level of the monimolimnion, under a greenhouse effect due the water density gradient. The energy transfer (0.06 °C m ^–1) by conduction toward the bottom sediments is very constant from one year to the next and is likely to prevent the presence of permafrost under this water body.In its chemical composition, this meromictic lake is quite comparable to the world's saltiest water bodies and is the first lake, with a salinity greater than sea water to be reported for the Canadian Arctic. Its anoxic monimolimnion is nearly three times (90) as salty as normal sea water.This hypersaline water seems to have been derived from isostatic trapped marine waters within the present lacustrine basin as well as from underground during deglaciation of the area. The subsequent freezing-out of salt from the underground waters and the migration and accumulation of these waters in the bottom of Garrow Lake through a talik within the permafrost were the main contributing factors. The speed of formation and migration of the underground brine was a function of the postglacial isostatic uplift rate as well as the permafrost growth rate.     

Thermal stratification and the stability of meromixis in the Pretoria Salt Pan,South Africa

The Pretoria Salt Pan, South Africa, a small (0.076 km²), shallow (Z_max = 2.85 m), hypersaline, maar lake, lies within a clearly-defined crater and is fed by a perennial, slightly saline (3 g l^-1) artesian spring. The lake has two distinct solar-heated peaks in its temperature profile, each of these peaks located in a highly turbid (>80 JTU) layer below a steep chemocline. The upper thermal peak, located at a depth of 10 cm, was transient, with a distinct diel pattern of diurnal heating and nocturnal cooling. The lower thermal peak, located below a steep chemocline and centred at approximately 60 cm, was stable and showed a seasonal pattern of winter heating (maximum: 38.5°C) and summer cooling (minimum: 27.4°C). The unusual bathymetry of the lake, combined with the sheltering effect of the crater rim and steep salinity gradient between the surface (30–80 g l^-1) and bottom water (280–310 g l^-1) prevented windmixing of surface waters beyond a depth of approximately 50 cm. During a 28 month study all water deeper than 55 cm remained anaerobic, and the lake appeared to be meromictic.