Notes on Diatoms V. : Epilithic Diatom Biomass in the Des Moines River

Luxuriant epilithic growths of the diatom, Gomphonema olivaceum (Lyngbye) Kutz., were observed to be growing throughout a 320 km section of the Des Moines River. Flat rocks covered with the diatom growth were collected and the live weight of the diatom biomass per square centimeter was determined to be 0.7 gm. This included 0.021 gm dry weight of organic matter. Using these values, the standing epilithic diatom biomass in one 6 km section of the river was estimated to be 1260 metric tons (live weight) containing 37.6 metric tons dry weight of organic matter. The bulk of the growth consisted of polysaccharide material secreted as tubular stalks by G. olivaceum. Extensive growths were usually limited to rocky shoals and riffle areas, composed of either cobbles and boulders of glacial origin, or of rock rubble of local origin

Diatoms In The Des Moines River

Diatoms were observed to be the dominant algal group in all seasons in the 860 km long Des Moines River, from April 1961 through September 1964. The 9 most abundant diatom taxa were: Diatoma vulgare, Gomphonema olivaceum, Melosira granulata, Nitzschia dissipata, N. palea, Stephanodiscus hantzschii, Synedra acus and S.ulna. Of the 60 most abundant diatom taxa in the Des Moines River, 36 are important components of diatom floras in other major United States Rivers. From over 600 samples collected year around and throughout the length of the river, 274 diatom taxa representing 38 genera were identified. No new diatom taxa were recognized. Diatoms and a water sample were collected weekly. Water samples were analysed for: temperature, pH, turbidity, sulfate, iron, phosphate, silica, nitrite, nitrate, methyl orange alkalinity, chloride, calcium hardness, total hardness, oxygen, and manganese. The river basin climate produced 5 distinct positive growth periods for diatoms each year; these were characterized by heavy benthic, attached, and planktonic (except in winter) diatom growth; and delimited or terminated by one of 5 distinct respective \u27\u27antigrowth periods\u27\u27 of highwater. The latter periods were typified by heavy silt loads, and removal of most diatoms from the river by flushing and scouring. Sources of diatoms for repopulating the river were the two headwater lakes, numerous tributaries, migratory animals, and impoundments in the upper and middle zones of the river itself. Motility is an important survival factor for diatoms settling out with silt in river impoundments, and 80% of the Des Moines River diatoms are motile forms. Flow (water volume) and available light were probably the most important limiting factors for diatom growth in all seasons in the Des Moines River, both in turn limited by precipitation in the drainage basin. Light penetration most probably was limited by ice and snow cover and turbidity; in addition to precipitation, high turbidity was also caused by effluents from commercial washing of sand and gravel. Seasonal temperature variation also regulated the kinds of dominant and abundant diatoms. Ample nutrients, especially nitrates and phosphates, for diatom growth were provided by inorganic fertilizers washed from farmlands and sewage and related effluents from over 500,000 people. The intrinsic fertility of the Des Moines River is insignificant under these conditions. It is estimated that during positive growth periods over l000 tons per month of diatoms and other algae were produced in and carried out of the river; the vast amount of diatom primary production in the Des Moines River is probably utilized negligibly by other organisms. Two large dams, at Saylorville and Red Rock, will alter the diatom growth patterns in the Middle and Lower portions of the river as well as providing the opportunity for a stratified sedimentary deposition of diatoms. The impoundments from these dams will probably result in a change in the kinds of dominant diatoms and increase the number of taxa collectable

Notes on Iowa Diatoms III. Occurrence of the Genus Pleurosigma in the Des Moines River

A member of the diatom genus Pleurosigma was collected from the Des Moines River from 12 stations. Earlier investigators did not report it. This organism may be suitable as an ecological indicator, since most members of the genus occur in salt or brackish water. Positive identification was not made, the organism is probably a variety of P. delicatulum Wm. Smith

Notes on Iowa Diatoms. VI. Frustular Aberrations in Surirella Ovalis

Two types of frustular aberrations in cultures of Surirella ovalis Breb. have been observed. The first is a notch deformity occurring in approximately 0.1% of the population. It is produced by mechanical distortion where the cells are crowded. This deformity is passed to daughter cells in each successive vegetative division. The second type is characterized by the presence of one or more aberrant raphe canals crossing the valve face in various directions. It occurred only in cultures exposed to continuous light for two weeks. Little or no cell division occurred during this period. The raphe canal aberrations, which occurred in about 0.01% of the exposed population, may have resulted from abortive cell divisions. They were not observed to continue in later transfers of the exposed populations to normal growth conditions

|Research Focus Star Trek replicators and diatom nanotechnology

Diatoms are single celled algae, the 10 5 –10 6 species of which create a wide variety of three-dimensional amorphous silica shells. If we could get them to produce useful structures, perhaps by compustat selection experiments (i.e. forced evolution of development or evodevo), their exponential growth in suspension cultures could compete with the lithography techniques of present day nanotechnology, which have limited 3D capabilities. Alternatively, their fine detail could be used for templates for MEMS (micro electro mechanical systems), or their silica deposition systems isolated for guiding silica deposition. A recent paper has demonstrated that silica can be replaced atom for atom without change of shape – a step towards the Star Trek replicator. Given that diatoms are responsible for,25 % of the world’s net primary production [1] they have been the most underfunded organism per unit mass. This might be about to change with a flurry of activity in a new field dubbed ‘diatom nanotechnology’, which will have its debut in a workshop at the next North American Diato