A series of five stations, arranged as a bottom transect away from shore between the depths of 15 centimeters and 5 meters, was studied. During the three-month period of study (June, July, and August, 1964) there was an evident seasonal succession of dominant diatom species at all stations. In general, the greatest fluctuations in the dominant elements of the flora were noted in the shallower stations. Besides being more seasonally stable, the floras of the deeper stations were relatively more diverse on all dates sampled

Hostetter, H. P.

Stoermer, E. F.

University of Northern Iowa

Proceedings of the Iowa Academy of Science Volume 75 Annual Issue Article 10 1968 A Study of the Vertical Distribution of Periphyton Diatoms in Lake West Okoboji, lowa H. P. Hostetter University of Arizona E. F. Stoermer University of Michigan Let us know how access to this document benefits you Copyright ©1968 Iowa Academy of Science, Inc. Follow this and additional works at: https://scholarworks.uni.edu/pias Recommended Citation Hostetter, H. P. and Stoermer, E. F. (1968) "A Study of the Vertical Distribution of Periphyton Diatoms in Lake West Okoboji, lowa," Proceedings of the Iowa Academy of Science, 75(1), 42-47. Available at: https://scholarworks.uni.edu/pias/vol75/iss1/10 This Research is brought to you for free and open access by the Iowa Academy of Science at UNI ScholarWorks. It has been accepted for inclusion in Proceedings of the Iowa Academy of Science by an authorized editor of UNI ScholarWorks. For more information, please contact scholarworks@uni.edu. A Study of the Vertical Distribution of Periphyton Diatoms in Lake West Okoboji, lowa1 H. P. HosTETTER2 and E. F. STOERMER3 Abstract. A series of five stations, arranged as a bottom transect away from shore between the depths of 15 centimeters and 5 meters, was studied. During the three-month period of study (June, July, and August, 1964) there was an evident seasonal succession of domi-nant diatom species at all stations. In general, the greatest fluctua-tions in the dominant elements of the flora were noted in the shallower stations. Besides being more seasonally stable, the floras of the deeper stations were relatively more diverse on all dates sampled. The ecology of periphyton algae has evoked the interest of numerous investigators. It is widely recognized that diatoms are an important element in most such communities. Aleem (1949, 1950) has investi-gated naturally occurring communities in a littoral zone of the Brit-ish coast. Castenholz (1960) has investigated the seasonal changes in periphyton communities in fresh and saline lakes in the western United States and has ( 1963) conducted experimental investigations of the seasonal .colonization rates of marine littoral diatoms. Blum (1956) reviewed the literature concerning such communities in lotic environments, and more recently Sladeckova ( 1962) has provided an excellent review of the methods used in periphyton investigations. In reports of his investigations of primary productivity in periphyton communities, Wetzel (1964, 1965) has reviewed the literature par-ticularly pertinent to productivity investigations. The aims of the present investigation were to determine the depth distribution of dominant periphyton diatom species and the fluctua-tions in their relative abundance over relatively short time periods. Our previous observations led us to believe that both the species composition and the absolute quantity of diatom biomass in periphyton communities fluctuated widely during different periods of collection and at different collection depths. METHODS The area selected for study was a bottom transect running due west from the southern tip of Fort Dodge Point on Lake West Okoboji, Iowa. This area has a steeply sloping bottom that is uniformly cov-ered with glacial cobbles and boulders down to a depth of about 9 meters. By use of free diving apparatus, hand samples were taken at depths of 15 centimeters, 1, 2, 3, 4 and 5 meters. The stations selected were sampled on 20 June, 19 July, and 6 August, 1964. On the latter two sampling dates the temperatures at each station lThls research was conducted at Iowa Lakeside Laboratoey in the summers of 1964 and 1965 during the senior author's tenure as an NSF Fellow in ti>.~ Summeir Fellowship for Graduate Teaching Assistants Program. 2Departrnent of Biological Sciences, University of Arizona. 3Gre!1-t J.akes Research Division, University of Michigan, 42 1Hostetter and Stoermer: A Study of the Vertical Distribution of Periphyton Diatoms in LakPublished by UNI ScholarWorks, 19681968] VERTICAL DISTRIBUTION OF DIATOMS 43 sampled were recorded, and water sampJes for chemi.cal analysis were taken at the shallowest and at the deepest stations sampled. After recovery the biological samples were split. One-half of each sample was preserved in standard formalin-acetic add-alcohol preser-vative and retained as a reference collection. The remaining portion of each sample was "cleaned" by the method of VanderWerff (1956). Permanent slides suitable for identification of the diatom species pres-ent were then made using Hyrax as a mounting medium. Measure-ments of the frequency of dominant diatom species were obtained by identifying and recording all specimens in random oil immersion (lOOOX) fields. Counts were continued until a total of 500 specimens had been identified from each slide. Water samples taken in conjunction with this study were returned to the laboratory and analyzed within one hour after collection. RESULTS Collection 1 was made on June 20, 1964. Although the water tem-perature was not recorded, there was no temperature discontinuity perceptible to divers working in the area within the depth sampled. There was a perceptible temperature discontinuity at the depth of 9 meters. At this time a luxuriant growth of Cladophora covered the rocks at all depths sampled. Frequency of the diatom species recovered from these sampJes is shown in Table 1. To facilitate discussion those species which com-prised less than 5 percent of the total flora have been placed together in the "rare" category, and their cumulative frequencies rather than the frequency of each species is recorded. It will be noted that there is relatively little differentiation of the flora with depth in these sam-ples. Cocconeis pediculus is abundant at all depths although its abundance does drop rather strikingly at the 5-meter depth. The total number of species per sample and, concomitantly, the percentage contribution of the rare species tend to increase with depth. Table I Frequency of Di.atom Species in Samples Taken 20 June. Where no numerical figure is given the frequency is less than 5 percent. Frequency in Percent Sample Depth 15 cm. lm. 2m. 3m. 4m. Sm. 43 87 55 47 73 15 43 25 29 8 5 9 5 7 6 5 18 6 6 13 15 10 14 56 8 11 9 13 22 65 Cocconeis pediculus Ehr ................ . Gomphonema olivaceum (Lyngb.) Klitz. . . Synedra vaucheriae (Klitz.) Peters. . ..... . Cymbella prostrata (Berkeley) Cleve .... . Achnanthes sp. . ............•........... Rhoicosphenia curvata (Klitz.) Grun. . .. . Fragilaria intermedia (Grun.) ........... . Amphora ovalis var. pediculus Klitz ...... . Nitzschia dissipata (Klitz.) Grun. . ...... . Rare species (cumulative total) ......... . '!otal number of species counted per sample 2Proceedings of the Iowa Academy of Science, Vol. 75 [1968], No. 1, Art. 10https://scholarworks.uni.edu/pias/vol75/iss1/1044 IOWA ACADEMY OF SCIENCE [Vol. 75 Collection 2 was taken on July 19, 1964. The floristic results from this series of samples are presented in Table 2. Temperature and water chemistry data for this sample are recorded in Table 3. It will be noted that the thermodine has developed between 4 and 5 meters. During this sampling period it was noted that Cladophora was absent from the 4- and 5-meter stations and that the plants which occurred at the other sampling depths appeared depauperate. The differentia-tion of the flora with depth is somewhat better developed than in the first series of· samples. The most striking discontinuity appears to o.ccur between the 3- and 4-meter stations. This difference is re-flected both in the frequent elements of the flora and in the total species composition. Table 2 Frequency of Diatom Species in Samples Taken 19 July. Where no numerical figure is given the frequency is less than 5 percent. Frequency in Percent Sample Depth 15 cm. lm. 2m. 3m. 4m. 5m. Cocconeis pediculus Ehr. ................ 69 84 86 65 Synedra vaucheriae (Klitz.) Peters. ....... 11 Epithemia turgida (Ehr.) Klitz. .......... 12 Amphora ovalis var. pediculus Klitz. ...... 21 18 Fragilaria intermedia Grun. .............. 18 13 Stephano discus niagarae Ehr. ............ 5 Rare species (cumulative total) .......... 20 16 14 23 61 64 Total number of species counted per sample 18 15 18 21 80 80 Table 3 Temperature and Water Chemistry; Collection II. 15 cm. 1 m. 2m. 3m. 4m. 5m. Temperature . . . . . 27° C. 27° C; 26° C. 25° C. 25° C. 22° c. 193 ppm (CaC03) 11.2 ppm 210 ppm (CaCOa) Alkalinity (total) . 19 7 ppm (CaC03} (P) . . . 12.5 ppm Total hardness . . . 212 ppm (CaCOs) Iron . . . . . . . . . . . . None detected Nitrate . . . . . . . . . . 0.009 ppm Nitrite . . . . . . . . . . 0.016 ppm Phosphate (total as P04).. 0.26 ppm Sulfate . . . . . . . . . . 26 ppm pH . . . . . . . . . . . . • 8.68 ----------None detected 0.04 ppm 0.09 ppm 0.16 ppm 31 ppm 8.66 ·---·--·-----Collection 3 was taken on August 6, 1964 (Table 4). Physical and chemical data taken at this time as shown in Table 5 reveal substan-tial. alteration in the environment. It will be noted that the water is isothermal at all depths sampled and that there is a small net decrease in surface temperature and an appreciable increase in temperature at the 5-meter depth relative to the previous sampling date. Probable 3Hostetter and Stoermer: A Study of the Vertical Distribution of Periphyton Diatoms in LakPublished by UNI ScholarWorks, 19681968] VERTICAL DISTRIBUTION OF DIATOMS 45 cause for this is to be found in the very heavy rains which occurred approximately one week before the date of sampling and which caused a net rise in lake level of approximately 15 centimeters. Another heavy rain fell two days before the time of sampling. Floristic data from this series of samples indicate further differentiation of the flora with depth. In most cases there is a definite peak frequency of occur-rence at a particular depth. Table 4 Frequency of Diatom Species in Samples Taken 6 August. Where no numerical figure is given the frequency is less than 5 percent. Frequency in Percent Sample Depth 15 cm. 1 m. 2 m. 3 m. 4 m. 5 m. Gomphonema olivaceum (Lyngb.) Ki.itz. 28 Synedra acus Klitz. . . . . . . . . . . . . . . . . . . . . . 60 C occoneis pediculus Ehr, ............... . Epithemia turgida (Ehr.) Ki.itz.) ........ . Amphora ovalis var. pediculus Klitz ...... . Gomphonema gracile var. aurita (A. Braun Cleve) ................... . Epithemia sp. . ........................ . Rhoicosphenia curvata (Ki.itz.) Grun ..... . Fragilaria intermedia Grun. . ............ . Cocconeis placentula Ehr. . ............. . Navilcula scutelloides Wm. Smith ....... . Rare species (cumulative total) . . . . . . . . . . 12 Total number of species counted per sample 14 Table 5 38 6 5 51 45 21 38 6 35 35 7 5 12 23 10 6 37 41 Temperature and Water Chemistry; Collection III. 15 cm. Temperature . . . . . 26° C. Alkalinity (total) . 197 ppm (P) . . . 12 ppm Total hardness . . . 200 ppm Iron ............ None detected Nitrate . . . . . . . . . • 0.25 ppm Nitrite . . . . . . . . . . 0.009 ppm Phosphate (total as P04) .. Sulfate ......... . pH ············· Silica .......... . 0.10 ppm 23 ppm 8.64 8.0 ppm 1 m. 2 m. 3 m. 4 m. 26° c. 26° c. 26° c. 26° c. DISCUSSION 31 9 5 10 5 40 54 Sm. 15 6 18 15 5 41 60 26° C. 195 ppm lOppm 204 µpm None detected 0.045 ppm 0.014 ppm 0.18 ppm 28 ppm 8 .. 19 8.0.ppm Perhaps a salient feature of our results is the consistently increasing diversity of the diatom flora with increasing depth. In all instances the highest total number of species and the highest percentage contri-bution to the total flora by rare species were found at the deepest stations sampled. This result is reasonable in terms of physical factors 4Proceedings of the Iowa Academy of Science, Vol. 75 [1968], No. 1, Art. 10https://scholarworks.uni.edu/pias/vol75/iss1/1046 IOWA ACADEMY OF SCIENCE [Vol. 75 of the environment. An organism living at greater depths should be less subject to drastic changes in temperature and solar radiation and is effectively insulated from the destructive effects of wave action. It would also appear that at least in this particular environment the diatom species are less subject to competition from other algal groups which are less well adapted to growing under conditions of low ambient light. The competition factors are aptly illustrated in the case of Coc-coneis pediculus. This organism is particularly well adapted to epi-phytic growth upon Cladophora. As previously noted, the latter alga was the visible dominant during the periods of collection. It would appear, however, that the adaptation to epiphytic growth on this par-ticular substrate carries with it the penalty of less successful growth at a greater depth. In all instances Cocconeis pediculus reached its greatest abundance between the depths of 1 and 2 meters, and it was rarely abundant below the depth of 4 meters. Once the over-riding habitat preference influence of Cladophora was removed, as in the third series of samples, a greater diversity in the abundant elements of the diatom flora appeared together with an apparent depth prefer-ence for most of the abundant species. Examples of this may be seen in Amphora ovalis which occurred in all samples and was consistently most abundant between 4 and 5 meters depth, and in Rhoicosphenia curvata which was most abundant at a depth of 4 meters. Although observations cover only the mid-summer months of June, July, and August, some indications of the normal seasonal succession of dominant diatom species in this habitat are evident. Our previous observations have shown that Gomphonema oblivaceum is the visible dominant in this habitat during the spring and fall months. A rem-nant of this spring flora is still present in the June collections but is completely absent in the July collections. It would appear that the fall flora is beginning to establish itself in the August collections. Previous observations would lead us to believe this to be unusual in terms of the normal seasonal su.ccession in Lake West Okoboji, and this instance may be attributable to the premature early upset of summer stratification by the previously mentioned unusual weather conditions. The rise in lake level associated with unusually heavy rains is reflected in the overwhelming dominance of Synedra acus in the shallow station of the third series of collections. This species together with the recently established Gomphonema olivaceum com-prised nearly 90 percent of the flora at this station. Literature Cited Aleem, A. A. 1949. Distribution and ecology of marine littoral diatoms. Consid-eration of the littoral diatom flora with special reference to forms living in gelatinous tubes. Bot. Notiser 4:414-440. --. 1950. Distribution and ecology of marine littoral diatoms. J. Ecol 38 · 75-106. . . 5Hostetter and Stoermer: A Study of the Vertical Distribution of Periphyton Diatoms in LakPublished by UNI ScholarWorks, 19681968] VERTICAL DISTRIBUTION OF DIATOMS 47 Blum, J. L. 1956. The ecology of river algae. Bot. Rev. 22:291-341. Castenholz, R. W. 1960. Seasonal changes in the attached algae of freshwater and saline lakes in the Lower Grand Coulee, Washington. Limnol. Osceanogr. 5: 1-28. ---. 1963. An experimental study of the vertical distribution of littoral marine diatoms. Limnol. Oceanogr. 8:450-462. Sllideckovii, A. 1962. Linmological investigation methods for the periphyton (,,Aufwuchs" community. Bot. Rev. 28:287-350. Van der Werff, A. 1956. A new method of concentrating and cleaning diatoms and other organisms. Vehr. Int. Ver. Limnol. 12:276-277. Wetzel, R. G. 1964. A comparative study of the primary productivity of higher aquatic plants, periphyton, and phytoplankton in a large, shallow lake. Int. Rev. Hydro biol. 49: 1-61. ---. 1965. Techniques and problems of primary productivity measurements in higher aquatic plants and periphyton. Mem. Ist. Ital. Idrobiol. 18 Suppl: 249-267. 6Proceedings of the Iowa Academy of Science, Vol. 75 [1968], No. 1, Art. 10https://scholarworks.uni.edu/pias/vol75/iss1/10

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