Algae

Arkansas has a very diverse assemblage of algae. The majority of the research conducted on algae in the state is published in the Arkansas Academy of Science’s journal, but some is available in other journals and government publications. Most of the studies have been performed in northern Arkansas by Dr. Richard L. Meyer from the University of Arkansas (UA) in Fayetteville (Washington County). He and his graduate students undertook many studies that were developed into MS and PhD theses. The studies were performed in rivers (Buffalo, White, Arkansas, and Mississippi rivers), a few lakes (Lake Chicot, Lake Fort Smith, and Lake Fayetteville), a few smaller ponds, a stream, and an agricultural rice field. Three studies were done in Hot Springs National Park in the 1970s, 1980s, and 2006. The dominate algae form was Cyanobacteria.

Thomas Smith developed a comprehensive list of algal species identified in the state of Arkansas. This publication identified ten algal groups and a total of 1,387 species in Arkansas.

General Characteristics of Algae
Algae are a diverse polyphyletic group. Although they have caused dilemmas within taxonomy due to their diversity, morphology, and the evolution of the chloroplast, they have been well studied since the early twentieth century. The term “algae” is defined as any organism possessing the four following features, which distinguish them from other plants:

1)      Chlorophyll “a”: This photosynthetic pigment is the primary pigment that processes the sun’s energy and is used to create carbohydrates from inorganic compounds and gives off oxygen as a by-product.

2)      Body plan: There is no specialization of the algal body into root, stem, and leaves with vascular tissue. The photosynthetic portion of the alga is a thallus, while the attachment portion comprises hair-like rhizoids.

3)      No embryo: For most algae, sperm and eggs fuse in the open water, and the zygote develops into a new plant without any protection.

4)      Reproductive structures: The gametes are produced within a single cell. There is no jacket of sterile cells protecting the gametes.

This definition encompasses a number of plant forms that are not necessarily closely related evolutionarily, but it is still useful in identifying these organisms.

The algal taxonomic groups are further subdivided primarily on their photosynthetic pigments, carbohydrate reserve, and cell covering composition. Their morphology ranges in shape and size from a single-celled species of less than one micrometer to giant seaweeds over fifty meters. Algae are abundant and ancient organisms that can be found in virtually every ecosystem in the biosphere. For billions of years, algae have exerted profound effects on the planet’s oxygen atmosphere and its biosphere, and they continue to do so today. Algae are primary producers and the bases of the food chain. They are generally thought to be cosmopolitan (widely distributed) organisms.

Phycologists traditionally studied organisms that included and spanned both prokaryotic and eukaryotic domains; for simplicity, both prokaryotic and eukaryotic organisms will be included here.

Prokaryotic Organisms
Ernst Stizenberger (1860) split the prokaryotic organisms from Chlorophyceae into a recognizable taxonomic group, which he called Myxophyceae. R. Y. Stanier et al. (1978) coined the term Cyanobacteria and incorporated these organisms under the International Code of Nomenclature of Bacteria. This distinction is based on bacterial practices and morphology. He placed them in the group Myxophyceae. As prokaryotic organisms, they share all characteristics of this domain and kingdom: no nucleus, circular DNA, prokaryotic RNA, no membrane bound organelles, no sexual reproduction, and binary fission reproduction.

There are 337 Cyanobacteria species identified in Arkansas. Oscillatoriales is the most common filamentous order. Oscillatoriales is characterized by simple filaments without branching or false branching and without heterocysts, with and without mucilage sheaths. Common genera in this order are Phormidium, Lyngbya, Oscillatoria, and Leptolyngbya. Nostocales is the second-most-common order, and common genera are benthic Anabaena, Nostoc, and Calothrix. This order is characterized as having heterocysts, which are specialized vegetative cells that undergo nitrogen fixation in the absence of oxygen.

Chroococcales is common in Arkansas, while there are only a few species in the order Stigonematales that have been identified. Chroococcales is spherical in shape and imbedded into a mucilage matrix. Order Stigonematales seems to be morphologically most developed with true branching, heterocysts, and complicated life cycles.

Eukaryotic Organisms
Bacillariophyta (diatoms) are the most common algal division in Arkansas. Diatoms are unique as having silica as a cell wall matrix. Only a few other groups share this characteristic. Diatoms have been subdivided into three classes: Centric diatoms (Coscinodiscophyceae), Pennate diatoms without a raphe (a seam) (Fragilariophyceae), and those with at least a partial raphe present (Bacillariophyceae). Bacillariophyceae is the most common class of diatoms with the common genera as Navicula, Pinularia, Gomphonema, and Cymbella. Fragilariophyceae and Coscinodiscophyceae are less common. Common genera in Fragilariophyceae are Fragilaria and Synedra. Coscinodiscophyceae are cylindrical, typically with spines, and are planktonic.

Charophyta (stoneworts) and Chlorophyta (green algae) are very common divisions in Arkansas. Both divisions have similar photosynthetic pigments, carbohydrate reserve, and cell covering materials. The main difference is during cytokinesis (the cell plate formation). The microtubules from the spindle apparatus form parallel to the cell plate (phycoplast) as in Chlorophyta. Charophyta’s microtubules form perpendicular to the cell plate (phragmoplast), which is the type of cytokinesis high plants exhibit. Common genera of Charophyta are branching (Chara), filamentous(Spirogyra, Mougeotia), and desmid genera (Pleurotaenium, Cosmarium,, Micrasterias, Staurodesmus). Common genera to Chlorophyta are Ankistrodesmus, Chlamydomonas, Cladophora, Oocystis, Scenedesmus, Ulothrix, and Volvox.

Heterokontophyta (heterokont) and Euglenozoa (euglenoids) are smaller species that are widespread in Arkansas. The most common heterokonts are Chrysophyceae and Synurophyceae, while Xanthophyceae is less conspicuous. Euglena, Phacus, and Trachelomonas are the common genera in Euglenozoa. Uncommon divisions in Arkansas are Dinophyta (dinoflagellates), Cryptophyta (cryptomonads), Haptophyta (haptophytes), and Rhodophyta (red algae).

For additional information:
Eichman, J. “The Influence of Nutrients, Flow Characteristics and Geological Substrate of the Community Ecology of Periphytic Diatoms.” MS thesis, University of Arkansas, 1991.

Hoffman, C., and D. Causey. “Limnological Studies in Arkansas: 1. Physico-Chemical and Net Plankton Studies of Lake Fort Smith in Its Fourth Year of Impoundment.” Proceedings of the Arkansas Academy of Science 5 (1952): 55–72.

Kay Shipley-Phillips, J. “Developmental Morphogenesis and Phylogeny in Pleurotaenium.” PhD thesis, University of Arkansas, 1991.

Meyer, R. “The Desmids (Conjugatophycean) from Arkansas.” Proceedings of the Arkansas Academy of Science 50 (1996): 110–114.

———. “The Freshwater Algae of Arkansas: Introduction and Recent Additions.” Proceedings of the Arkansas Academy of Science 23 (1969): 145–156.

———. “The Freshwater Algae of Arkansas II: New Additions.” Proceedings of the Arkansas Academy of Science 24 (1970): 32–35.

———. “Notes on the Algae of Arkansas I: Chrysococcus, Kephyrion, Kephyriopsis, Pseudokephyrion, and Stenokalyx.” Proceedings of the Arkansas Academy of Science 25 (1971): 32–41.

Placke, J. “Some Observations on the Nychthemeral Distribution of Phytoplankton in a Shallow Pond.” MS thesis, University of Arkansas, 1979.

Rippery, L. “Spatial and Temporal Distribution of Algae and Selected Water Quality Parameters in the Buffalo River, AR.” MS thesis, University of Arkansas, 1977.

Robinson, A. “Comments on the Bacillariophyceae of North Central Arkansas.” Proceedings of the Arkansas Academy of Science 6 (1953): 51–52.

Smith, G. “The Role of Study of Algae in the Development of Botany.” American Journal of Botany 43 (1956): 537–543.

Smith, T. “Algae in Agricultural Fields from St. Francis County, Arkansas.” Proceedings of the Arkansas Academy of Science 62 (2009): 97–102.

———. “Revised List of Algae from Arkansas, U.S.A. and New Additions.” International Journal on Algae 12.3 (2010): 230–256.

Stanier, R. Y., et al. “Proposal to Place the Nomenclature of the Cyanobacteria (Blue-Green Algae) under the Rules of the International Code of Nomenclature of Bacteria.” International Journal of Systematic Bacteriology 28 (1978): 335–336.

Tankersley, J. “Thermophilic Blue-Green Algae in Hot Springs National Park.” MS thesis, East Texas State University, 1970.

Toon, S. “The Ultrastructure and Taxonomic Position of Boecklovia Hooglandii Nicoli & Baas–Becking.” MS thesis, University of Arkansas, 1987.

Woomer, N. “Periphyton Succession and Production in a Stream.” PhD thesis, University of Arkansas, 1986.

Thomas Smith
Ave Maria University