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At least 343 records · Page 19Linked to original sources
USGS2003

Geology and biology of the sea floor as deduced from simulaneous photographs and samples

During 1963, 260 paired photographs and large bottom samples were taken on the continental shelf and slope off northeastern United States. The photographs revealed surface characteristics of the sediments and natural attitudes of benthic animals; the samples retrieved specimens for geological and biological examination and identification. Samples are the best source materials for making textural studies of sediments consisting mostly of sand, silt, or clay, but photographs are better than samples for bottoms too bouldery for proper sampling. Ripple marks and other surface irregularities revealed by the photographs supplement textural studies of the samples in deducing effects of wave movements and currents upon bottom materials. For biological studies, the photographs yield much information on relationships of the benthic fauna to bottom materials, but they fail to provide useful data on biomasses. Biomasses and accurate taxonomic identifications are far better made upon samples. Thus, a combination of photographs and accompanying samples provides maximum information for biological as well as geological purposes.

Limnology and Oceanography↗
USGS2003

Eutrophication of the St. Lawrence Great Lakes

Lakes Huron, Michigan, and Superior are classified as oligotrophic lakes on the basis of their biological, chemical, and physical characteristics. Lake Ontario, although rich in nutrients, is morphometrically oligotrophic or mesotrophic because of its large area of deep water. Lake Erie, the most productive of the lakes and the shallowest, is eutrophic. Several changes commonly associated with eutrophication in small lakes have been observed in the Great Lakes. These changes apparently reflect accelerated eutrophication in the Great Lakes due to man's activity. Chemical data compiled from a number of sources, dating as early as 1854, indicate a progressive increase in the concentrations of various major ions and total dissolved solids in all of the lakes except Lake Superior. The plankton has changed somewhat in Lake Michigan and the plankton, benthos, and fish populations of Lake Erie are greatly different today from those of the past. An extensive area of hypolimnetic water of Lake Erie has developed low dissolved oxygen concentrations in late summer within recent years.

Limnology and Oceanography↗
USGS2003

Changes in the bottom fauna of western Lake Erie from 1930 to 1961

Samples were collected at 40 stations in western Lake Erie in 1961 to determine the species composition, distribution, and abundance of macrobenthonic organisms and to document changes since 1930, when a similar survey was made. The fauna in 1961 was composed principally of Oligochaeta, Tendipedidae (7 genera), Sphaeriidac (15 species), and Gastropoda (at least 8 species). Stations with a high density of Oligochaeta were near the principal sources of pollution (Maumee, Raisin, and Detroit rivers). Stations with fewer Oligochacta and a more diverse fauna were farthest from the river mouths. The population density of the burrowing mayfly, Hexagenia spp., was reduced from an average of 139/m 2 in 1930 to less than 1/m 2 in 1961. Organisms more abundant near the sources of pollution than in other areas were, in addition to Oligochaeta: the midge, Procladius; the fingernail clam, Sphaerium transversum; and the snail, Valvata sincera (sens. lat.). Organisms sensitive to pollution, such as amphipods, mayfly nymphs, caddisfly larvae, and naiad clams, were scarce and usually at the more lakeward stations. The most important changes in fauna during the 31-year period were: ninefold increase in Oligochacta; fourfold increase in Tendipedidae; twofold increase in Sphaeriidae; sixfold increase in Gastropoda; and a reduction of Hexagenia to less than 1% of former abundance. The area of pollution (as judged from the abundance of Oligochaeta) increased from 263 km 2 in 1930 to 1,020 km 2 in 1961.

Michigan, Ohio↗
USGS2003

The relative toxicities of several pesticides to naiads of three species of stoneflies

Static bioassays were conducted to determine the relative acute toxicities of some insecticides, herbicides, fungicides, a defoliant, and a molluscicide to the naiads of three species of stonef!y, Pteronarcys califomica, Pteronarcella badia, and Claassenia sabulosa. Toxic effects were measured by determination of median lethal concn (Lcoo) for 24-, 48-, and 96-hr exposures, at 15.5C. Endrin and dieldrin were the most and DDT the least toxic of the chlorinated hydrocarbon insecticides tested. Parathion was the most toxic organophosphate insecticide to P. califomica naiads, but dursban was the most toxic to P. badia and C. sabulosa naiads. Trichlorofon ( Dipterex) was the least toxic to all three species. P. badia, the species of smallest size, was the species most susceptible to most pesticides, followed in descending order of sensitivity by C. sabulosa and P. califomica. Smaller specimens of P. californica naiads were consistently more susceptible to some insecticides than larger specimens of the same species.

Limnology and Oceanography↗
USGS2003

Daytime distribution of Pontoporeia affinis off bottom in Lake Michigan

The vertical migration of the amphipod Pontoporeia affinis in Lake Michigan has been well documented by Wells, Marzolf, and McNaught and Hasler. Wells and Marzolf observed Pontoporeia off bottom only at night. McNaught and Hasler, however, found Pontoporeia above the bottom shortly after noon in a 24-hr study on 12 June 1965, and some individuals were taken just below the thermocline in all daylight hours in a similar study on 19-20 August. This paper presents evidence that Pontoporeia regularly were present above bottom during the day from April-August 1964. The data for this report were collected during a study of seasonal and depth distribution of larval bloaters (Coregonus hoyi) in Lake Michigan. Sampling was conducted from the U.S. Bureau of Commercial Fisheries RV Cisco off Saugatuck, Michigan, at intervals of about 10 days from 9 April to 14 August 1964. A few samples were taken on 22 August and 15 October.

Limnology and Oceanography↗
USGS2003

Vertical density currents — II

Examples of vertical density currents wholly within the domain of laminar flow, one in a water solution, the other in air, have come to my attention. Both examples illustrate new ways of introducing and dispersing microscopic particles into static fluids and both demonstrate that a stable, clearly defined layer of dispersed particles forms first and that the vertical density currents originate and flow from the lower part of this layer. The new information comes from wholly unrelated lines of research, one in virology, and the other in mycology. Neither investigation was aimed at hydrodynamics yet both provide good experimental support for vertical density currents.

Limnology and Oceanography↗
USGS2003

Effects of toxicants on community metabolism in pools

Estimates of community metabolism of simulated natural environments were dcrivcd by diel oxygen techniques over a period of nine months. During this time, toxicants were added to some of the pools. "Natural" environmental factors and toxicants that did not affect the communities (0.02 mg/liter p,p' DDT; 0.1 mg/liter antimycin A; and 9.2 mg/liter KMnO,I) usually resulted in simultaneous changes, up or down, in both community photosynthesis and respiration. Concentrations (mg/liter) of 0.9 and 2.6 formalin, 10.0 nigrosine black, 10.0 and 2.0 malachite green, 0.1 Diquat, and 0,.5 and 5.0 CUSO.~ usually tlcprcsscd community oxygen production and increased community respiration for periods of 1 to 20 weeks.

Limnology and Oceanography↗
USGS2003

Distribution of oligochaetes in western Lake Erie, 1961

A total of 52,390 oligochaetes were collected from 40 stations in western Lake Erie in spring 1961. The population was composed of two families, Naididae and Tubificidae. Only six species of naidids were found. One, Paranais frici, is apparently new to the list of North American freshwater Naididae. Among the 14 tubificids found, five species of Limnodrilus were most abundant; they contributed 90% or more of all oligochaetes at 33 of the 40 stations. Numbers of Limnodrilus were generally large near the mouths of the Detroit, Raisin, and Maumee rivers and decreased progressively lakeward. Stylodrilus heringianus, a pollution-intolerant species common in eastern Lake Erie, was not found in the western end of the lake.

Limnology and Oceanography↗
USGS2003

The influence of nitrogen on heterocyst production in blue-green algae

A series of experiments on heterocyst production in Anabaena variabilis provides some strong indirect evidence for the role of heterocysts in nitrogen fixation. Of the algae tested ( Anabaena variabilis, A. inaequalis, A. cylindrica, A. flos-aquae, Tolypothrix distorta, Gloeotrichia echinulata, Aphanizomenon flos-aquae, Oscillatoria sp. , and Microcystis aeruginosa ), only those with heterocysts grew in a nitrate-free medium. Growth in the nitrate-free medium was accompanied by an increase in heterocysts. Heterocyst formation in A . variabilis was evident 24 hr after transfer from a nitrate-containing to a nitrate-free medium. The number of heterocysts was altered by changes in the nitrogen source. Numbers were lowest when NH 4 -N was used as a nitrogen source and highest when nitrogen (N 2 -N) was derived from the atmosphere. Heterocyst numbers could also be regulated by controlling the concentration of NO 3 -N in the medium. Heterocyst production depended on the absence of combined nitrogen and the presence of phosphate. Data are presented on the occurrence of blue-green algae (with heterocysts) in Lake Erie and the environmental conditions apparently necessary for them to become dominant.

Limnology and Oceanography↗
USGS2003

Seasonal fluctuations of Lake Michigan diatoms

Diatoms were collected in four areas of Lake Michigan and in southern Green Bay from April to early November 1965. The flora of the lake was characterized by Fragilaria crotonensis, Tabellaria flocculosa, Melosira islandica, Cyclotella 'glomerata-stelligera,' Cyclotella michiganiana, Asterionella formosa, and Stephanodiscus tenuis. Stephanodiscus niagarae always dominated the diatom biomass in Green Bay; also characteristic of the bay were Melosira granulata, Melosira ambigua, Melosira binderana, Fragilaria capucina, and Fragilaria crotonensis. There was an average of 517 diatoms per ml in the lake and 944 in the bay. Diatom abundance appeared to have one peak in the lake and two in the bay. At times of maximum abundance, optimum depth was usually 5 m. Numbers were greater in Green Bay and the inshore areas than in the offshore areas and appreciably higher near the eastern shore than the western shore of the lake. The higher populations near the eastern shore and in Green Bay appeared to be correlated with higher concentrations of phosphorus and chlorophyll a and lower concentrations of nitrate-N.

Limnology and Oceanography↗
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↗