1. Freshwater Phytoplankton Key for the Northeast By: Rachael Brown, Sonya Carlson, and Diana Jackson Under the guidance of Dr. Alan Baker NEXT

2. Introduction: This photographic key is intended to aid in identification of freshwater algae to the Genus level. Proceed through this key by clicking on the picture that most resembles your organism. Buttons to know: Home: Go to the beginning page at any time Back: Go to the last page viewed Forward: Go to the next page in the key To Start Key Click Here START

3. Cells with definite chloroplasts and nuclei, not blue-green in color Cells without definite chloroplasts and nuclei, blue-green in color

4. Vegetative cells usually grass-green in color and with a definite cell wall Vegetative cells not grass-green

5. Vegetative cells yellowish to brown with a glass-like silica wall of two overlapping halves Vegetative cells yellow-green with a cell wall

6. Class: Chrysophyceae

7. Class: Cyanophyceae Common Name: Cyanobacteria, blue-greens Continue to Genus

8. Rectangular Is the general contour of the specimen: Elongate strands of cellsOblong, Circular, or Globular Sperm shaped Note: A filament is a strand of cells arranged end to end

9. Are the filaments: Unbranched Branched Elongate filaments of cells

10. Genus: Microthamnion

11. Filaments are found alone Unbranched: Filaments form together in parallel colonies (rafts)

12. Option A: Oblong Option B: Circular Option C: Globular Oblong, Circular, or Globular

13. Head has thin membrane Head has thick wavy membrane Sperm-Shaped

14. Genus: Aphanocapsa

15. Genus: Aphanothece

16. Genus: Chroococcus

17. Genus: Coelosphaerium

18. Genus: Gloeocapsa

19. Genus: Microcystis

20. Genus: Merismopedia

21. Genus: Cylindrospermum

22. Genus: Gloeotrichia

23. Genus: Anabaena

24. Genus: Aphanizomenon

25. Genus: Calothrix

26. Genus: Chamaesiphon

27. Genus: Lyngbya

28. Genus: Nostoc

29. Genus: Oscillatoria

30. Filaments are joined at one end Filaments are parallel and are not joined together at any end

31. Filaments have elongate cells arranged end to end Filaments have horizontal cells that are stacked on top of each other

32. Filaments Found Alone Cells are round and are arranged in long filaments (like strands of pearls) Elongate unicells are found on a substrate unicells

33. Cell shape is rectangular Cell shape is oblong

34. Filaments are spaced apart from each other Filaments are lumped together

35. Option A: Oblong Cells float freely apart from each other Cells join in even numbers and have a clear membrane around them

36. Option B: Circular Cells are free floating with thin clear membranes Cells are congregated and encased in a round membrane

37. Encased Cells Cells are encased by a clear membrane Cells are encased in a thick green membrane

38. Order: Bacillariophyceae Common Name:Diatoms Continue to Genus

39. Is the shape of the organism rectangular? Is the shape of the organism circular or oval? Does organism have stalks?

40. Are there many rectangles joined together? Are the rectangles separate from each other?

41. Do the rectangles make a line or stairstep formation? Do the rectangles form a star? Do the rectangles form a box?

42. Genus: Tabellaria

43. Genus: Asterionella

44. Genus: Eunotia

45. Width (W) of individual cells is 1/10 of the length (L) W L W L Width (W) of individual cells is 1/5 of the length (L)

46. Genus: Fragilaria

48. Are there many small circles within the cells? Is the end of the cell a long spike or is there a few large circles within the cells?

49. Genus: Melosira

50. Genus: Rhizosolenia

51. Is the middle of the cell wider than either end? Is the end of the cell opposite of the stalk the widest section?

52. Genus: Cymbella

53. Genus: Gomphonema

54. Are there smaller circles within the large circle? Are there lines around the edge of the circle? Is the shape of the organism oval?

55. Genus: Cocconeis

56. Genus: Cyclotella

57. Is the cell extremely long and skinny with the length (L) more than 15 times as much the width (W)?

58. Genus: Synedra

59. Are the ends of the cell pointed (p) or rounded (r) )? Are the ends of the cell curved (c)? Are the ends of the cell flat (f)?

60. Genus: Gyrosigma

61. Genus: Amphora

62. Is the cell the same width in the middle as it is nearer to the ends? (a is equal to b) Is the cell the wider in the middle than it is nearer to the ends? (a is larger than b)

63. Is the edge of the oval smooth? Does the edge of the oval have a distinct bump? Bump Smooth

64. Is there a distinct line down the length of the cell? Distinct Line Is no distinct line visible in the center of the cell?

65. Is the center area of the middle line is wider than the ends of the middle line with a distinct break in the center? Is the middle line even in width with a distinct break in the center? Is the middle line complete with no distinct break in the center?

66. Genus: Navicula

67. Genus: Frustulia

68. Genus: Opephora

69. Is the cell long and skinny with the length (L) more than 5 times as much the width (W)? Is the cell short with the length (L) less than 5 times as much the width (W)?

70. Genus: Diatoma

71. Genus: Amphipleura

72. Genus: Surirella

73. Are there distinct parallel lines extending from the middle of the cell to the edge? Is the interior of the cell a homogenous color without lines? Lines

74. Genus: Achnanthes

75. Genus: Rhopalodia

76. Are the ends distinctly pointed? Are the ends distinctly rounded?

77. Genus: Nitzschia

78. Genus: Pinnularia

79. Actinastrum

80. Ankistrodesmus

81. Apiocystis

82. Arthrodesmus

83. Bulbochaete

84. Carteria

85. Centritractus

86. Chaetophora

87. Chaetosphaeridium

88. Characiopsis

89. Characium

90. Chlamydomonas

91. Chlorella

92. Chlorococcum

93. Cladophora

94. Closterium

95. Coelastrum

96. Coelosphaerium

97. Coleochaete

98. Cosmarium

99. Crucigenia

100. Desmidium

101. Dictyosphaerium

102. Dimorphococcus

103. Docidium

104. Euastrum

105. Eudorina

106. Gloeocystis

107. Gonium

108. Haematococcus

109. Hormidium

110. Hyalotheca

111. Hydrodictyon

112. Kirchneriella

113. Micractinium

114. Micrasterias

115. Microspora

116. (Conjugating) Mougeotia

117. Oedogonium

118. Onychonema

119. Oocystis

120. Palmella

121. Palmellocystis

122. Pandorina

123. Pediastrum

124. Planktosphaeria

125. Pleurotaenium

126. Scenedesmus

127. Selenastrum

128. Spirogyra

129. Staurodesmus

130. Tetraedron

131. Ulothrix

132. Volvox

133. Xanthidium

134. Zoochlorella

135. Zygnema

136. COLONIES (GROUPS OF CELLS) FILAMENTS (LINEARLY) CELLS ARE ARRANGED IN… SINGLE CELLS Class: Chlorophycae

137. COLONIES ARE… FLAT (2-D)SPHERICAL (3-D)

138. CELLS IN FILAMENTS HAVE… ONE CHLOROPLAST TWO CHLOROPLASTS MANY CHLOROPLASTS

139. SINGLE CELLS ARE… UNICELLULARHEMISPHERES

140. INDIVIDUAL CELL SHAPE IS… SPHERICAL OR ELLIPTICAL LONG OR ROD SHAPED SPIKEY

141. COLONIES HAVE… TIGHTLY PACKED CELLS SPACE BETWEEN CELLS

142. FILAMENTS ARE… SINGULAR BRANCHED

143. HEMICELLS ARE… LONG AND NARROW SEMICIRCULAR

144. CHLOROPLASTS ARE… CLUMPED SPIRALED

145. ARE CELLS IN THE FILIMENT… SHORT LONG

146. Does your algae look like any of these?