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2 June 2015



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Metal atoms in Cyclotella meneghiniana (see Marginalia below)



Lake Willoughby, Essex County, Vermont
Diatoms -- "the paragon of animalcules"

This group of unicellular, photosynthetic microorganisms is well-known for a wonderous, intricate architectural beauty. However, there is more to a diatom than simply its pretty face. As a major branch in the tree of life, over the past 250 million years from a mosaic of genetic sources it has evolved molecular metabolic machinery adaptive to a variety of circumstances, and it has generated a species diversity rivalling that of flowering plants. Diatoms have evolved to become important local and global players in recycling life's critical nutrients, influencing the composition of the earth's environments and powering the planet's aquatic ecosystems, as well as elucidating their history. This web site focusses on their evolution and ecology.

(
Above) Light microscope serial-focus and composite images of the glass cell wall of the diatom Asteromphalus from the Bering Sea. See About Images for explanation of focussing.

 

1 May 2015 The lost recovery from eutrophication:a cautionary tale of climate change from a lake in Saxony.

The Beauty of Diatoms: from the Marine Food Web to Nanotechnology by Mark Hildebrand, Scripps Institution of Oceanography ((video, 50 min) - an introduction to diatoms - their basic cell biology, ecology and application to nanotechnology from a lecture in 2004


Diatoms: the evolution of a new species by Richard Dawkins, The Richard Dawkins Foundation & University of Nebraska State Museum (video, 2 min 10 sec)

The scale of diatoms: Quick zoom-in on the cell wall of Arachnoidiscus using an electron microscope (ZeissImaging, 29 sec)

 

Commentary and notes on diatom evolution
and ecology and the history of their study

Metals in diatoms. An exploration of the roles of metals in diatom metabolism.

 

(Above) Video (50 sec) of a single cell of the diatom Cyclotella meneghiniana imaged using x-ray flourescence tomography showing the 3-dimensional spatial distribution of elementally different metal atoms (from M. D. de Jonge et al. 2010. Proceedings of the Academy of Sciences USA 107:1576).

The diatom cell. An introduction to the organelles of diatoms.



Transmission electron micrograph of the chloroplast in the diatom Melosira varians. Image: microscopy of Richard Crawford in J. Dodge's Fine Structure of Algal Cells (1975), Academic Press.

How diatoms got their name. Diatoms - cleft confervas, or carved at the joints.


A colony of Diatoma. Image: Christian Linkenheld

Fragilaria crotonensis -- a "queer form" in the fountains of New York City


Washington Square Park, New York City, ca. 1855; fountain not flowing. Image: Luther S. Harris (2003) Around Washington Square: an illustrated history of Greenwich Village, JHU Press. Original photo by Silas A. Holmes, The J. Paul Getty Museum.

A calendar and perspectives on the evolution
and ecology
of diatoms and other phytoplankters
in the lakes of northern Vermont


Complete Archive

diatom.org's posters of Vermont lakes and online Primer & Guide
exploring the application of mathematics and computer science
to the study of lakes including:

  • • basic arithmetic and trigonometric operations, use of reciprocals, fractions, roots, exponentiation, order of operations
  • • digital measurement of distances and angles
  • • estimation of medial axis by eye, inscribed circles, Voronoi diagrams and skeletonization
  • • estimation of surface area by fitted simple and compounded geometric figures, mosaics of triangles employing Heron's concept of semiperimeter, the surveyor's (Gauss's) area formula employing vector cross products, and pixel censusing
  • • the formation of binary images, masks, and contour extractions
  • • reading bathymetric sounding charts
  • • converting bathymetric soundings to bathymetric contours using simple linear interpolation
  • • converting bathymetic soundings to grids involving nearest neighbor, neighborhood, inverse distance and inverse-squared distance interpolations
  • automated measurement of surface area and perimeters enclosed by contours by means of contour tracking
  • construction of two-dimensional color-coded plots of depth contours
  • • construction of three-dimensional color-coded models of lake shape with contours in wire-frame and full-panel perspectives, and the rotation and tilting of the models
  • • the conversion of contour surface areas into volume versus depth plots
  • • the construction of hypsographic plots (absolute, relative, double relative) and Hakanson transformed hypsographic plots
  • • the classication of lakes based on hypsographic features

The 24" x 36" (61 x 91 cm) posters and guide are expected online
in early summer 2015.


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