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At least 145 records · Page 8Linked to original sources
USGS2003

Mud Lake, Florida: Its algae and alkaline brown water

Mud Lake (Marion County, Florida), in the Ocala National Forest, is elliptical, has an area of ca. 180 ha, and a mean depth of less than 50 cm. The water contains about 200 ppm dissolved solids, ranges from brown to nearly colorless (15 to 100 Pt units), and is always alkaline ( p H 7.7 to 10.2). Dissolved Fe, Ca, PO 4 , tannin-lignin, and the specific conductance, color, and temperature of the water were measured monthly for 1 yr, and temperature and p H were measured many other times during the 3-yr study (1966–1968). The lake is surrounded by a zone of mixed hardwood swamp flora and a floating mat of vegetation and has no submerged higher plants and only 1 or 2 m 2 of emergent plants. The lake sediment consists exclusively of minute fecal pellets produced mainly by chironomid larvae and composed solely of blue-green algae. Myxophyceae are represented by at least 10 genera and 12 species, which live exclusively on, or in, the fecal pellets; less than half show a seasonal distribution. The Chlorophyceae consist dominantly of Spirogyra triplicata with minor amounts of Sirogonium sp. and generally occur in enormous winter blooms, correlated with changing amounts of dissolved PO 4 and apparently inversely with both temperature and incident light. Bacillariophyceae are represented by 18 species and varieties, but the total population is small. Nanno-, zoo- and phytoplankton are extremely rare, probably because of the prevailing high intensity illumination and the extremely shallow water. Only the fish population is large, and this is dominated by minnows, gars, and sunfish. The midge population is remarkably small. A bacterial inhibitor probably accounts for the small population of bacteria both in the water and in the top layer of the sediment.

Florida↗
USGS2003

Cisco ( Coregonus artedii ) mortalities in a southern Michigan lake, July 1968

Cisco die-offs are common in the summer in certain lakes of northern Indiana and southern Michigan, along the southern boundary of the national distribution of coregonine fishes. Although numerous cisco die-offs have been reported, few, if any, have been accompanied by environmental information at the time of the die-off. On 31 July and 1 August 1968, we investigated a cisco die-off on Halfmoon Lake, on the border of Washtenaw and Livingston Counties, Michigan.

Limnology and Oceanography↗
USGS2003

Effects of alewife predation on zooplankton populations in Lake Michigan

The zooplankton populations in southeastern Lake Michigan underwent striking, size-related changes between 1954 and 1966. Forms that decline sharply were the largest cladocerans (Leptodora kindtii, Daphnia galeata, and D. retrocurva), the largest calanoid copepods (Limnocalanus macrurus, Epischura lacustris, and Diaptomus sicilis), and the largest cyclopoid copepod (Mesocyclops edax). Two of these, D. galeata and M. edax (both abundant in 1954), became extremely rare. Certain medium-sized or small species increased in numbers: Daphnia longiremis, Holopedium gibberum, Polyphemus pediculus, Bosmina longirostris, Bosmina coregoni, Ceriodaphnia sp., Cyclops bicuspidatus, Cyclops vernalis, and Diaptomus ashlandi. Evidence is strong that the changes were due to selective predation by alewives. The alewife was uncommon in southeastern Lake Michigan in 1954 but had increased to enormous proportions by 1966; there was a massive dieoff in spring 1967, and abundance remained relatively low in 1968. The composition of zooplankton populations in 1968 generally had shifted back toward that of 1954, although D. galeata and M. edax remained rare. The average size, and size at onset of maturity, of D. retrocurva decreased noticeably between 1954 and 1966 but increased between 1966 and 1968.

Limnology and Oceanography↗
USGS2003

Suspended matter in surface waters of the northern Gulf of Mexico

Analyses of about 200 surface water samples collected during late fall 1966 show that concentrations of suspended matter greater than 1 mg/liter were restricted to within a few kilometers off Florida, but extended more than 100 km off Louisiana and Texas. Suspensates from areas farther than 100 km from shore contained mainly combustible organic matter, part of which was attributable to living plankton. Organic aggregates encompassing appreciable amounts of inorganic detritus were particularly noteworthy in transitional areas. Zooplankton metabolism and fecal pellet production appears to be a geologically significant mechanism for depositing fine suspended matter and may contribute to the zonation of bottom sediments. The mineral composition of surface suspensates ranges from a low magnesian calcite‐aragonite suite off Florida to montmorillonite‐kaolinite combinations from Alabama to Texas. The mineral composition of the suspensates resembles that of the bottom sediments in each area.

Northern Gulf of Mexico↗
USGS2003

Transient and steady-state salt transport between sediments and brine in closed lakes

A diffusional transport model for Lake Abert, Oregon, predicts the rates of salt transport from pore fluids into lake waters. In a lake without outflow dissolved salts may migrate across the sediment-water interface in response to a concentration difference between lake and interstitial brine. Transport of salt upward is transient; its direction can be reversed by external input of salt or by depletion of salts stored in the sediments, and a steady-state concentration in lake water is not attainable. Downward transport can be a stationary process if the sedimentation rate is rapid compared with molecular diffusion of salt in interstitial brine, but characteristic rates arc too slow to lead to steady-state concentrations within the lifetime of a closed lake. In Lake Abert, diffusional flux upward was much more important than input of salt from other sources; 45% of the salt of lake brine in 1963–1964 was added from the sediment pore space during the preceding 25 years, only 0.1% from external inflow. The sediment source will dominate input during high water level. Such models permit comparison of salt transport across the sediment-water interface with other input sources at different times of the lake’s history.

Oregon↗
USGS2003

Phosphorus, iron, and manganese distribution in sediment cores of six Wisconsin lakes

Depositional patterns of iron, manganese, and phosphorus in one central and five northern Wisconsin lakes ranging from oligotrophic to eutrophic, primarily from natural causes, have been investigated. One-meter cores from one or more locations within each lake were analyzed. The historical pattern of iron and manganese deposition is closely related to the pattern of phosphorus deposition in most of the cores. Four of the nine cores show a strong positive correlation coefficient between P and Fe and seven between P and Mn. Manganese has more predictive value than iron for determining the concentration of phosphorus in a given core; however, the iron content appears to be the dominant factor in the phosphorus sorptive and retentive capacity of sediments.

Wisconsin↗
USGS2003

Deposition of zinc and cadmium by marine bacteria in estuarine sediments

Mixed cultures of marine bacteria isolated from the sediments of Corpus Christi Harbor were examined for their ability to assimilate or precipitate radioactive zinc and cadmium from solution. Test data indicate that during summer, when bacterial activity is at a maximum, the bacteria and their metabolic byproducts play a significant role in the removal of zinc and cadmium from seawater and their subsequent deposition in marine sediments.

Texas↗
USGS2003

Movement of spilled oil as predicted by estuarine nontidal drift

Information on water movement obtained from bimonthly releases of surface and seabed drifters in the San Francisco Bay and adjacent Pacific Ocean is used to understand major processes controlling dispersal of oil after a spill of 3,200 m3 of Bunker C in the bay in January 1971. River-induced nontidal estuarine circulation was the dominant factor controlling net movement of the oil spilled at the entrance of the bay system, reinforcing ebbing tidal currents and causing the seaward movement of floating oil, which followed paths taken by surface drifters released 3 weeks before the spill. In contrast, some oil formed globules which sank to the near-bottom waters, had the same relative buoyancy as seabed drifters, and moved similarly, beaching in eastern San Pablo Bay after being transported landward in the near-bottom waters. No oil or surface drifters floated into the south bay because surface waters were drifting seaward, away from the south bay. Notable seasonally modulated phenomena which must be considered in predicting surface and near-bottom oil drifts of future spills include a summer (low-river discharge period) diminution of the estuarine circulation mechanism in the north and central bayadjacent ocean region and a seasonal reversal in two-layer drift in the south bay.

California↗
USGS2003

Determination of sulfate in seawater and natural brines by 133Ba and membrane dialysis

Dissolved sulfate is determined by precipitation with the radioisotope 133 Ba and counting of the precipitate on a scintillation counter. Precipitation is carried out in dialysis bags; excess 133 Ba is removed via diffusion by soaking the bags in distilled water for 12 h, and the bags are then placed directly in the well of the scintillation counter. The procedure eliminates previous errors caused by washing and transferring of the precipitate and permits analysis of 0.5–3,000 µ g·ml −1 sulfate in a 1.0-ml sample. The detection limit is increased by simply increasing the sample volume up to 5.0 ml. The technique is interference-free in natural waters ranging from freshwater to brines of 1.5 times the salinity of seawater.

Limnology and Oceanography↗
USGS2003

Methanogenic activity in plankton samples and fish intestines A mechanism for in situ methanogenesis in oceanic surface waters

When plankton samples were incubated anaerobically with a cysteine-sulfide reducing agent, pronounced methane evolution occurred. This activity was inhibited by air, CHCl 3 , C 2 H 2 , and 2-bromoethanesulfonic acid. Adding [ 14 C]CO 3 2− resulted in accumulation of [ 14 C]CH 4 . Portions of the digestive tracts of three fishes were incubated in methanogenic media, and two of the samples showed the presence of methanogenic bacteria.

Limnology and Oceanography↗
USGS2003

High frequency radar measurements of tidal currents flowing through San Pablo Strait, San Francisco Bay

High frequency (HF) radar measurements of the surface current averaged over the upper 0.5 m in San Pablo Strait were compared with current meter measurements of the subsurface current made at 9.4 m below mean lower low water (MLLW) over two 12.4-h tidal cycles. After averaging the radar and current meter data over two tidal cycles, a southerly (ebbing direction) surface current of 32 cm·s −1 was deduced from the radar measurements and a northerly (flooding direction) subsurface current of 7 cm·s −1 from the current meter measurements. This nontidal flow is maintained by freshwater discharge from the Sacramento–San Joaquin Rivers into Suisun and San Pablo Bays. The radar measurement technique provides quantitative estimates of the surface currents that previously were determined only from surface drifter studies.

Limnology and Oceanography↗
USGS2003

The chemical composition of lakes in the north‐central United States

Lake waters of the north‐central U.S.A. are classified into five groups, based on increasing specific conductivity and changes in ionic composition from east to west, from Wisconsin through Minnesota to North and South Dakota. The most dilute group of waters has specific conductivities <29 µ mhos · cm −1 at 25°C; the most concentrated group has specific conductances that range from 7,000 to 73,000 µ mhos. As conductivity increases all major ions increase, but there is a shift in cation dominance from Ca 2 + to Mg 2+ to Na + , and in anion dominance from HCO 3 − to SO 4 2− . This shift partly reflects a westward increase in climatic aridity, and partly a westward sequence of glacial drifts from noncalcareous to calcareous and thence to calcareous with abundant sulfur‐bearing minerals. Levels of pH, K, Cl, F, B, and SiO 2 also show a distinct westward increase. Concentrations of NO 3 − and Mn increase from east to west, but the trend is less distinct. Concentrations of Fe vary widely without any trend over the range of conductivity. Color, mostly from dissolved organic matter, is controlled chiefly by lake depth, except for lakes with extensive peatlands in their drainage basins.

Minnesota, North Dakota, South Dakota, Wisconsin↗
USGS2003

Big Soda Lake (Nevada). 1. Pelagic bacterial heterotrophy and biomass

Bacterial activities and abundance were measured seasonally in the water column of meromictic Big Soda Lake which is divided into three chemically distinct zones: aerobic mixolimnion, anaerobic mixolimnion, and anaerobic monimolimnion. Bacterial abundance ranged between 5 and 52 x 10 6 cells ml &minus;1 , with highest biomass at the interfaces between these zones: 2&ndash;4 mg C liter &minus;1 in the photosynthetic bacterial layer (oxycline) and 0.8&ndash;2.0 mg C liter &minus;1 in the chemocline. Bacterial cell size and morphology also varied with depth: small coccoid cells were dominant in the aerobic mixolimnion, whereas the monimolimnion had a more diverse population that included cocci, rods, and large filaments. Heterotrophic activity was measured by [methyl- 3 H]thymidine incorporation and [ 14 C]glutamate uptake. Highest uptake rates were at or just below the photosynthetic bacterial layer and were attributable to small (<1 &micro; m) heterotrophs rather than the larger photosynthetic bacteria. These high rates of heterotrophic uptake were apparently linked with fermentation; rates of other mineralization processes (e.g. sulfate reduction, methanogenesis, denitrification) in the anoxic mixolimnion were insignificant. Heterotrophic activity in the highly reduced monimolimnion was generally much lower than elsewhere in the water column. Therefore, although the monimolimnion contained most of the bacterial abundance and biomass (&sim;60%), most of the cells there were inactive.

Nevada↗
USGS2003

Big Soda Lake (Nevada). 2. Pelagic sulfate reduction

The epilimnion of hypersaline, alkaline, meromictic Big Soda Lake contains an average 58 mmol sulfate liter &minus;1 and 0.4 &micro; mol dissolved iron liter &minus;1 . The monimolimnion, which is permanently anoxic, has a sulfide concentration ranging seasonally from 4 to 7 mmol liter &minus;1 . Depth profiles of sulfate reduction in the monimolimnion, assayed with a 35 S tracer technique and in situ incubations, demonstrated that sulfate reduction occurs within the water column of this extreme environment. The average rate of reduction in the monimolimnion was 3 &micro; mol sulfate liter &minus;1 d &minus;1 in May compared to 0.9 in October. These values are comparable to rates of sulfate reduction reported for anoxic waters of more moderate environments. Sulfate reduction also occurred in the anoxic zone of the mixolimnion, though at significantly lower rates (0.025&ndash;0.090 &micro; mol liter &minus;1 d &minus;1 at 25 m). Additions of FeS (1.0 mmol liter &minus;1 ) doubled the endogenous rate of sulfate reduction in the monimolimnion, while MnS and kaolinite had no effect. These results suggest that sulfate reduction in Big Soda Lake is iron limited and controlled by seasonal variables other than temperature. Estimates of the organic carbon mineralized by sulfate reduction exceed measured fluxes of particulate organic carbon sinking from the mixolimnion. Thus, additional sources of electron donors (other than those derived from the sinking of pelagic autotrophs) may also fuel monimolimnetic sulfate reduction in the lake.

Nevada↗
USGS2003

Big Soda Lake (Nevada). 3. Pelagic methanogenesis and anaerobic methane oxidation

In situ rates of methanogenesis and methane oxidation were measured in meromictic Big Soda Lake. Methane production was measured by the accumulation of methane in the headspaces of anaerobically sealed water samples; radiotracer was used to follow methane oxidation. Nearly all the methane oxidation occurred in the anoxic zones of the lake. Rates of anaerobic oxidation exceeded production at all depths studied in both the mixolimnion (2–6 vs. 0.1–1 nmol liter −1 d −1 ) and monimolimnion (49–85 vs. 1.6–12 nmol liter −1 d −1 ) of the lake. Thus, a net consumption of methane equivalent to 1.36 mmol m −2 d −1 occurred in the anoxic water column. Anaerobic methane oxidation had a first-order rate constant of 8.1±0.5 × 10 −4 d −1 , and activity was eliminated by filter sterilization. However, in situ methane oxidation was of insufficient magnitude to cause a noticeable decrease of ambient dissolved methane levels over an incubation period of 97 h.

Nevada↗
USGS2003

Big Soda Lake (Nevada). 4. Vertical fluxes of particulate matter: Seasonality and variations across the chemocline

Vertical fluxes of particulate organic matter were measured with sediment traps above and below the chemocline of Big Soda Lake to define the seasonality of sinking losses from the mixolimnion and determine the effectiveness of the chemocline (pycnocline) as a barrier to the sinking of biogenic particles. Seasonality of sedimentation rates reflected seasonal changes in the community of autotrophs. During summer-autumn, when production is dominated by autotrophic bacteria, vertical fluxes were small: 100 mg C m −2 d −1 and ≅0.5 mg Chl a m −2 d −1 . Following the winter diatom bloom, vertical fluxes increased markedly: ≅570 mg C m −2 d −1 and 23 mg Chl a m −2 d −1 . The bulk of the seston (> 80%) and particulate carbon (≅ 65%) sinking to the chemocline passed through it, showing that this very sharp density discontinuity does not effectively retard the sinking of particulate matter. However sinking losses of particulate carbon were generally small (≅10%) relative to previous measures of primary productivity, indicating that the mixolimnion is a zone of efficient carbon cycling. Exceptions occurred following the winter bloom when sinking losses were a larger fraction (≅40%) of productivity.

Nevada↗