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

Drum, Ryan W.

English

University of Northern Iowa

Proceedings of the Iowa Academy of ScienceVolume 70 | Annual Issue Article 171963Notes on Diatoms V. : Epilithic Diatom Biomass inthe Des Moines RiverRyan W. DrumIowa State UniversityCopyright © Copyright 1963 by the Iowa Academy of Science, Inc.Follow this and additional works at: https://scholarworks.uni.edu/piasThis Research is brought to you for free and open access by UNI ScholarWorks. It has been accepted for inclusion in Proceedings of the Iowa Academyof Science by an authorized editor of UNI ScholarWorks. For more information, please contact scholarworks@uni.edu.Recommended CitationDrum, Ryan W. (1963) "Notes on Diatoms V. : Epilithic Diatom Biomass in the Des Moines River," Proceedings of the Iowa Academy ofScience: Vol. 70: No. 1 , Article 17.Available at: https://scholarworks.uni.edu/pias/vol70/iss1/1774 IOWA ACADEMY OF SCIENCE [Vol. 70 We wish to thank Mr. Karl Holte for field assistance on numer-ous occasions. Literature Cited 1. Anderson, W. A. 1943. Am. Midland Nat. 29:787-791. 2. Caiter, Charles. 1939. Proc. Iowa Acad. Sci. 46:223-234. 3. Dodd, J. D. 1955. Proc. Iowa Acad. Sci. 62:98-103. 4. Gashwiler, K. and John D. Dodd. 1961. Proc. Iowa Acad. Sci. 68: 129-131. 5. Hempstead, D. L. and T. L. Jahn. 1939. Proc. Iowa Acad. Sci. 46:413-416. 6. Reimer, C. \V. 1961. Proc. Indiana Acad. Sci. 71:305-319. 7. Holte, K. and R. F. Thorne. 1962. Proc. Iowa Acad. Sci. 69:54-60. 8. Hustedt, F. 19.'30. Bacillariophyta. Heft 10 in A. Pascher's Die Suss-wasser-Flora Mitteleuropas. G. Fischer, Jena. 9. Boyer, C. A. 1916. The Diatomaceae of Philadelphia and Vicinity. Lippincott Co. ( Phila.) 10. Hustedt, F. 1959. Band VII Teil 2 in L. Rabenhorst's Kryptogamen-Flora. 11. van Heurck, H. 1880. Synopsis des Diatomees de Belgique. Anvers, Belgium. NOTES ON IOWA DIATOMS V. Epilithic Diatom Biomass in the Des Moines River 1 RYAN W. DRuM2 Abstract. L11,'l:uriant epilithic growths of the diatom, Gom-phonema olivaceum (Lyngbye) Kutz., were observed to be growing throucrhout a 320 km section of the Des Moines River. Flat rocks covered with the diatom growth were col-lected and the live weight of the diatom biomass per square centimeter was detennined 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) con-taining 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, com-posed of either cobbles and boulders of glacial origin, or of rock rubble of local origin. For several weeks in the fall of 1962, conditions in the Des Moines River were optimal for the epilithic growth of the dia-tom, Gomphonema olivaceum (Lyngbye) Kutz. Uniformly low temperatures ( 4-8°C), clear water, a nearly stable water level, abundant nutrients (see Table 1), and the absence o.f significant grazing populations all contributed to the favorable environment. Vast quantities of G. olivaceum flourished in the Des Moines River from October 20 to December 12 and continued to flourish in areas of open water throughout the winter months. 1 This work was supported by a Public Health Service grant from the Division of Water Supply and Pollution Control, Department of Health, Education and Welfare. • Department of Botany and Plant Pathology, Iowa State University, Ames, Iowa 1Drum: Notes on Diatoms V. : Epilithic Diatom Biomass in the Des MoinesPublished by UNI ScholarWorks, 19631963] DIATOM BIOMASS 75 Table l . Chemical data from the Des Moines River at the Fraser Dam, collected onNovember 28, 1962, at 1:30 p.m. Oxygen Iron Phosphate Silica itrate Nitrite 12 ppm 0.02 0.30 22.0 4.0 0.011 Sulfate Chloride Calcium Hardness Total H ardness Methyl Orange Alkalinity pH 95 ppm 19 200 460 270 8 .. '1 Figure 1. Large Tock shoal in Des Moines River, cmoposed mainly of cobbles and boulders. ( Boone Co., Iowa) Figure 2. W est Fork of the D es Moines River dowstream from tbe Highway 169 bridge at Humboldt, Iowa, showing a rock rubble riffle area 2Proceedings of the Iowa Academy of Science, Vol. 70 [1963], No. 1, Art. 17https://scholarworks.uni.edu/pias/vol70/iss1/1776 IOWA ACADEMY OF SCIENCE [VO:'.,. 70 In late November, 1962, during the course of a three-day sur-vey of the Des Moines River basin, from its headwaters at Lake Shetek, Minn., to its confluence with the Mississippi River south of Keokuk, Iowa, I observed and collected samples from ex-tremely luxuriant epilithic diatom growths on rocky shoals and riffie areas (Figures 1 and 2). Such growths were common at all sampling stations between Estherville, Iowa, and the Center Street Dam in Des Moines, Iowa. The magnitude of the diatom growth throughout this 320 km portion of the river was diffi-cult to estimate in meaningful units. Therefore, a quantitative determination was carried out in order to estimate the biomass of epilithic diatom growth. The results are reported in this paper. RESULTS Table 2. '¥ater, ashl, and organic matter composition of the epilithic dia-tom growths collected on November 28, 1962. Water Ash Organic Matter 81% 16% 3% 1 The high ash percentage is due to the particulate matter trapped within the colonies sampled. This includes silt and fine sand. Table 3. Epilithic Diatom Biomass, Des Moines River, November 28, 1962 Wet (Live) Weight Organic Matter (ash-free dry weight) Measured gm/cm2 0.7 0.021 Converted metric tons/ hectare 70 2.1 MATERIALS AND METHODS U.S. tons/acre 28 0:85 On November 28, 1962, three nearly Hat rocks were collected from an extensive rock shoal, comprised mainly of cobbles and boulders of glacial origin, at the YWCA bend in the Des Moines River in Boone Co. (T-85N, R-27W, Sec. 36). The diatom growth from the top surface of each rock was carefully removed, placed in a separate beaker and allowed to drain for 1 hour. The samples were then placed in porcelain crucibles, weighed on an analytical balance, and put in an oven at 45°C for 48 hours. They were weighed again and then kept at 60°C until constant weight was achieved. Higher temperatures were not used since such treatment might result in the loss of volatile cellular com-ponents. The samples were next ignited to ash at 800°C until constant weight was reached. From the data obtained in the above manner, the percentages of water, organic matter, and ash in the diatom growths were calculated (Table 2). The choice of rocks with flat surfaces permitted measurement of their respective areas with a planimeter and the calculation of weight per unit area (Table 3). The amount of live (wet) weight and the amount of organic matter are expressed both in metric tons per hectare and in U. S. tons per acre. Additional material was 3Drum: Notes on Diatoms V. : Epilithic Diatom Biomass in the Des MoinesPublished by UNI ScholarWorks, 19631963] DIATOM BIOMASS 77 sampled for light microscopic examination. Some of this ma-terial was vitally stained with ruthenium red. The remainder was cleaned with concentrated H 20 2 and K2 Cr20 7 , and used for taxonomic determinations and electron microscopy. No algal forms other than diatoms were observed in the material collected. DISCUSSION As noted above, the dominant diatom with respect to both numbers and biomass was Gomphonema olivaceum (Lyngbye) Kutz. An electron micrograph of the siliceous frustule of this organism is furnished in Figure 3. This organism secretes a poly-saccaride in the form of an extracellular tubular stalk, as seen in Figures 4 and 5. The stalks dichotomize with each vegetative cell division and reach lengths of up to 5 mm per cell. The bulk of the colonial mass consists of these stalks which are filled wit...li water. The structure of the Gomphonerna olivaceum colony has been discussed by Cholnoky ( l ) . Extensive growths of members of the diatom genus Gompho-nema in Iowa streams and rivers were observed and reported by Meyers ( 2) as early as 1898. Blum ( 3) has reported the oc-currence of luxuriant growths of G. olivaceum in streams and rivers in the vicinity of Ann Arbor, Michigan. When the water level drops as it did in the fall of 1962, the diatom-covered rock surfaces become exposed to air and sun-shine and the colonies dry down to a thin, white flaky layer. This same phenomenon was observed by Abdin ( 4) to occur in the Aswan Dam Reservoir when diatom colonies were exposed by a drop in the water level. This white covering remains on the rocks until it is washed away during periods of high water. Cobbles, boulders, and rock rubble that lay in flowing water, water that is either open or covered by no more than 5 cm of ice, have been observed to maintain extensive epilithic diatom growths throughout the winter months. An area of open water in the upper reaches of the Des Moines River, just south of the junction of the East and West Forks in Humboldt Co. (T-89N, R-28W), was visited on February 21, 1963. The open section was roughly 6 km long, and averaged 30 m in breadth.' with an almost uniform depth of about 50 cm. The river bottom appeared to be composed entirely of rock rubble of local origin. The water was very clear, and (with the aid of the midday sun) the entire bottom of the river was observed to be covered with a 1-2 cm blanket of Gomphonema olivaceum colonies. Large spheroidal colonies frequently broke loose from the rocks and floated to the surface of the river. Each of them contained a large gas bubble trapped within. If one assumes that the growth observed was fairly uniform throughout the 6 km section, then the values given in Table 3 4Proceedings of the Iowa Academy of Science, Vol. 70 [1963], No. 1, Art. 17https://scholarworks.uni.edu/pias/vol70/iss1/1778 Figure 3 . Figure 4. Figure 5 . IOWA ACADEMY OF SCIENCE 1mu::i. ~M\\WI: 1MMmm :\-\\~--~~~ :::ui:::m· •••• ~ .. , .......... j .\•"""" ., ..... ,, ..... ,.  .,.",'· ... .. ,,\.._, ............. .. [Vol. 70 E lection micrograph of Gcrmphonema olivaceum ( Lyngbye) Kutz. ( X5500 ) Light micrograph of G. olivaceum after staining the stalks with ruthenium red . (X550 ). Figure 5 . Light micrograph of two pairs of daughter cells of G . olivaceum prior to their respective formation of new stalk material. can be used to estimate the standing biomass of this segment of the D es Moines River. These values yield an estimate of 1260 metric tons of live weight, and 37.8 metric tons dry weight of organic matter (Respectively, these values convert to 1386 U. S. tons, and 41.6 U. S. tons.) . H ow important such vast quantities of epilithic diatoms may 5Drum: Notes on Diatoms V. : Epilithic Diatom Biomass in the Des MoinesPublished by UNI ScholarWorks, 19631963] DIATOM BIOMASS 79 be in terms of primary production is difficult to evaluate. It has been shown, however, that diatoms make up the bulk of the food of some insect larvae ( 5) and of several species of minnows in the Des :Moines River ( 6). The colonies provide a suitable habi-tat for many types of protozooans, rotifers, and aquatic worms. Many other diatom taxa are also found thriving among the stalks of G. olivaceum. ACKNOWLEDGEMENT The author wishes to thank Dr. John D. Dodd for his en-couragement during this study and Dr. C. C. Bowen for the use of the electron microscope facilities under his direction. Literature Cited 1. Cholnoky. B. 1927. Hedwigia 67:223-236. 2. Meyers, P. C. 1898. Proc. Iowa Acad. Sci. 6:47-52. 3. Blum, J. L. 1954. Pap. Mich. Acad. Sci. 39:3-7. 4. Abdin, G. 1952. Bull. Inst. Egyote 35:93-102. 5. Deonier, R. 1961. The Shore Flies of Iowa. M.S. Thesis, I.S.U., Ames. 6. Starrett, Ii\'. C. 1950. Ecology 31: 216-233. A Study of Photosynthesis in Clear Lake, lowa 1 CORNELIUS I. WEBER2 Abstract. The oxygen and carbon-14 methods were used to measure photosynthesis in Clear Lake, Iowa during 1958 and 1959. Differences in the rates of photosynthesis at widely separated stations were generally small. Daily variations in the rate of photosynthesis were not greater than two-fold. The correlation between the rate of photosynthesis and the incident illumination was 0.81, and the efficiency of utiliza-tion of incident light energy was 0.72 per cent. The net gain of organic matter at the phytoplankton level during the period l\Iay 1 to November 1 was equivalent to 3480 pounds of glucose per acre. Despite the basic position of planktonic algae in the food chain of aquatic environments there have been few extensive studies of food production by phytoplankton in well-defined eco-systems, and little has been done to follow quantitatively the How of organic matter from one level in the food chain to the next. A knowledge of the total food budget available at the primary level would contribute much to an understanding of fish popu-lation dynamics even though the food relationships between fish and phytoplankton are complex and generally obscure. This study of photosynthesis was undertaken to supplement studies of fish population dynamics that have been carried on in Clear Lake since 1941. Clear Lake has an area of approximately 1500 hectares and a 1 This study was conducted in the Department of Botany and Plant Pathology as a part of Project 11 of the Atomic Energy Commission under contract AT( 11-1 )59, ad-ministere dthrough the Institute for Atomic Research, Iowa State University, Ames, Iowa. 2 6985 Moorfield Drive, Cincinnati 30, Ohio 6Proceedings of the Iowa Academy of Science, Vol. 70 [1963], No. 1, Art. 17https://scholarworks.uni.edu/pias/vol70/iss1/17

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

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