At Station B, Aphanocapsa sp. (74% at 0 m, 10% at 1 m, 20% at 5 m, 76% at 10 m) and Aphanizomenon flos-aquae (20% at 0 m, 64% at 1 m, 45% at 5 m, 15% at 10 m) were the dominant algae. Chroococcus sp. (5% at 0 m, 20% at 1 m, 15% at 5 m, 6% at 10 m) was also present. Minor components were Oscillatoria (20% at 5 m), Anabaena spiroides, and various green algae.
Algal cell densities were low, <200 cells/ml in Station A collections and <100 cells/ml in Stationi B collections. The dominant phytoplankten in Buffalo Lake was the diatom Fragilaria crotonensis, which composed 45-83% of the population in all depths (0 m, 1 m, 5 m, 10 m) at both Stations A and B. Centric diatoms including Stephanodiscus sp.,made up to 6-27% in these collections. The dominant phytoplankten in Buffalo Lake was the diatom Fragilaria crotonensis, which composed 45-83% of the population in all depths (0 m, 1 m, 5 m, 10 m) at both Stations A and B. Centric diatoms including Stephanodiscus sp., composed 6-27% in these collections. The green alga Sphaerocystis schroeteri was present in all collections 3-14%) except in the 10 m samples and the 1 m sample from Station A. Minor constituents included Quadrigula chodatii, Asterionella formosa, Tabellaria sp. and Oocystis parva, among others.
An examination of the diatoms in the May collections from Buffalo Lake that revealed Fragilaria crotonensis was the dominant diatom, comprising 87-90% of the population at the depths sampled. Other diatoms were the centric Cyclotella comta (6-9%) and the pennates Asterionella formosa (to 3%) and Tabellaria sp. to 4%). A few cells of Navicula sp., Epithemia sp. and Synedra sp. were also found.
The September, 1986, phytoplankton assemblages at Buffalo Lake Stations A and B were dominated by the blue-green algae Microcystis aeruginosa, Anabaena flos-aquae, Gloeotrichia echinulata, all of which are common in eutrophic waters (Hutchinson 1967, Reynolds 1988).
Microcystis aeruginosa, a colonial, non-nitrogen fixing blue-green, may form nuisance blooms in stratified or slowly-flowing waters. The alga prefers nitrogen and phosphorus enriched waters. Some strains are toxic to vertebrate and invertebrate consumers (Paerl 1988).
The nitrogen fixing genus Anabaena is generally a sub-dominant in the phytoplankton of oligotrophic to eutrophic lakes, ponds and rivers. Anabaena can also form nuisance blooms in eutrophic waters, especially those enriched with phosphorus and organic matter. Maximum bloom development usually occurs in stratified waters during calm, warm weather (Paerl 1988). Certain species of Anabaena are known to be toxic to vertebrate and invertebrate consumers.
Gloeotrichia, also a nitrogen fixing genus of blue-green algae, is found attached in the plankton of oligotrophic to eutrophic streams, lakes and ponds (Paerl 1988). It is generally a subdominant, but may occur as a dominant in nuisance blooms. Aphanocapsa sp., another blue-green, is common in hypertrophic waters in late summer (Reynolds 1984a).
Oocystis, is a green alga, is usually found in ponds and shallow, fertile lakes, but some species may be dominant in deep unproductive lakes. Chroococcus, a non-nitrogen fixing genus of blue-green algae, is commonly a subdominant in mesotrophic to hypertrophic waters (Paerl 1988). It is frequently associated with bloom-forming blue-greens, but it rarely forms blooms itself.
The abundance of the nitrogen-fixing blue-green algae Anabaena and Gloeotrichia, both with numerous heterocysts, in the September 1986, phytoplankton indicates that nitrogen was probably limiting. The dominance of the phytoplankton by the blue-green algae (Anabaena flos-aquae, Aphanocapsa sp. And Chroococcus with some Anabaena spiroides) is characteristic of lakes having high levels of nutrient availability.
The algae abundant in the May, 1987, collections Fragilaria crotonensis, Stephanodiscus sp., a dinoflagellate (probably Peridinium sp.), and Asterionella formosa are considered indicative of mesotrophic to eutrophic conditions (Hutchinson 1967, Reynolds 1984a).
Asterionella formosa is often considered eutrophic. It may be found in both oligotrophic as well as eutrophic waters (Wetzel 1975, Stevenson 1985). Asterionella and Fragilaria crotonensis is associated with eutrophication in temperate waters (Taylor, et al. 1981). Stoermer and Yang (1970) call the taxon eutrophic but observed that it did not do well in highly polluted waters where high nitrogen:phosphorus ratios occur. Stegenson (1985) reports that Fragilaria crotonensis is not as competitive in waters that are phosphorus-rich and poor in nitrogen or silicon
Sphaerocystis schroeteri is frequently found in ponds and in shallow fertile lakes, but may be present with desmids in oligotrophic lakes mesotrophic conditions. Oocystis, a green alga poorly represented in the May samples, is usually found in ponds and shallow, fertile lakes, but some species have been found as dominants in deep unproductive lakes (Hutchinson 1967).
In summary, the phytoplankton samples taken from Buffalo Lake in September, 1986, and May, 1987, contain algae commonly found in mesotrophic to eutrophic conditions. The presence of these taxa, together with the moderate algal densities observed, indicate that the lake is mesotrophic.
Sample Depth Phytoplankton Algal Cells per ml Percentage
Surface
Microcystis aeruginosa 389 73%
Anabaena flos-aquae 81 15%
Chroococcus sp. 55 10%
1 Meter
Anabaena flos-aquae 167 59%
Aphanocapsa sp. 54 19%
Gloeotrichia echinulata 32 11%
Chroococcus sp. 26 9%
5 Meter
Aphanocapsa sp. 257 76%
Anabaena flos-aquae 55 16%
Chroococcus sp. 13 4%
Anabaena spiriodes 9 3%
unicellular green alga 6 2%
10 Meters
Aphanocapsa sp. 64 51%
Anabaena sp. 35 28%
Anabaena flos-aquae 18 14%
Chroococcus sp. 9 7%
Sample Depth Phytoplankton Algal Cells per ml Percentage
Surface
Aphanocapsa sp. 194 74%
Anabaena flos-aquae 52 20%
Chroococcus sp. 12 5%
1 Meter
Anabaena flos-aquae 65 64%
Chroococcus sp. 21 20%
Aphanocapsa sp. 10 10%
Anabaena spiroides. 4 4%
5 Meters
Anabaena flos-aquae 102 45%
Aphanocapsa sp. 45 20%
Oscillatoria sp. 44 20%
Chroococcus sp. 24 11%
Chroococcus cf. prescotti 10 4%
10 Meters
Aphanocapsa sp. 120 76%
Anabaena flos-aquae 23 15%
Chroococcus sp. 9 6%
Anabaena spiriodes 4 3%
Spring , 6 May 1987
Station A
Sample Depth Phytoplankton Algal Cells per ml Percentage
Surface
Fragilaria crotonensis 153 78%
Stephanodiscus sp. 19 10%
Sphaerocystis schroeteri 15 8%
Quadrigula chodatii 5 2%
1 Meters
Fragilaria crontonensis 85 75%
Stephanodiscus sp. 21 19%
Peridinium willei 3 3%
Tabellaria sp. 3 2%
5 Meters
Fragilaria crotonensis 117 67%
Sphaerocystis schroeteri 24 14%
Stephanodiscus sp. 18 10%
Quadrigula chodatii 6 3%
Peridinium willei 4 2%
Asterionella formosa 3 2%
10 Meters
Fragilaria crontonensis 99 79%
Tabellaria sp. 12 10%
Stephanodiscus sp. 8 6%
Asterionella formosa 5 4%
Sample Depth Phytoplankton Algal Cells per ml Percentage
Surface
Fragilaria crotonensis 43 45%
Stephanodiscus sp. 26 27%
Sphaerocystis schroeteri 14 14%
Quadridgula chodatii 6 6%
Asterinella formosa 6 6%
Tebellaria sp. 2 2%
1 Meter
Fragilaria crotonensis 74 60%
centric diatoms 19 16%
Quadrigula chodatii 11 8%
Sphaerocystis schroeteri 10 8%
Tabellaria sp. 7 6%
5 Meters
Fragilaria crotonensis 96 69%
centric diatoms 22 16%
Tabellaria sp. 5 4%
unidentified unicellular alga 4 3%
Sphaerocystis schroeteri 4 3%
Oocystis parva 3 2%
Quadrigula chodatii 3 2%
10 Meters
Fragilaria crotonesis 151 83%
Tabellaria sp. 10 5%
centric diatoms 9 5%
Asterionella formosa 6 3%
unicellular alga 4 2%