Phytoplankton abundance and composition relationships within the surface layer changed over short time periods (4-6 hours) in comparison with more constant associations at 2 cm below the surface. Both strata had a diverse algal flora (\u3e50 taxa), but no distinct neuston assemblage characterized the surface layer algal composition over the 24-hour study. The similarity between the two strata indicated the floral composition of the surface layer came from the water column algae below the surface. Chlorophytes, diatoms, cyanobacteria, and cryptophytes represented the most abundant algal categories for both strata with a total mean phytoplankton abundance of 3,566 cells ml-1 at the surface and 40,532 cells ml-1 at 2 cm over the 24 hours. The autotrophic picoplankton had generally similar levels of abundance over time. Their mean abundance for the 24 hours was 469 and 599 X 103 cells ml-1 at the surface and 2 cm respectively

Burchardt, Lubomira

Marshall, Harold G.

Wilk-Woźniak, Elżbieta

English

Old Dominion University

Old Dominion University ODU Digital Commons Biological Sciences Faculty Publications Biological Sciences 2005 Comparison of Phytoplankton and Autotrophic Picoplankton Populations Over a 24-Hour Period From a Pond's Surface and Subsurface Waters Harold G. Marshall Old Dominion University, hmarshal@odu.edu Lubomira Burchardt Elżbieta Wilk-Woźniak Follow this and additional works at: https://digitalcommons.odu.edu/biology_fac_pubs  Part of the Biology Commons, and the Fresh Water Studies Commons Original Publication Citation Marshall, H. G., Burchardt, L., & Wilk-Wozniak, E. (2005). Comparison of phytoplankton and autotrophic picoplankton populations over a 24-hour period from a pond's surface and subsurface waters. Oceanological and Hydrobiological Studies, 34(3, Suppl.) 229-235. This Article is brought to you for free and open access by the Biological Sciences at ODU Digital Commons. It has been accepted for inclusion in Biological Sciences Faculty Publications by an authorized administrator of ODU Digital Commons. For more information, please contact digitalcommons@odu.edu. Oceanological and Hydrobiological Studies Vol. XXXIV, Supplement 3 Institute of Oceanography I Research Article! (229-235) 2005 University of Gdansk COMPARISON OF PHYTOPLANKTON AND AUTOTROPHIC PICOPLANKTON POPULATIONS FROM A POND'S SURFACE AND SUBSURFACE WATERS OVER A 24-HOUR PERIOD HAROLD G. MARSHALL1•, LUBOMIRA BURCHARDT2, ELZBIETA WILK-WOZNIAK3 1 Department of Biological Sciences, Old Dominion University Norfolk, Virginia, U.S.A. 2 Department of Hydrobiology, Adam Mickiewicz University Poznan, Poland 3 Institute of Natural Conservation, Department of Freshwater Biology, PAS Krakow, Poland •e-mail: hmarshal@odu.edu Key words: neuston, picoplankton, phytoplankton, pond, Virginia. Abstract Phytoplankton abundance and composition relationships within the surface layer changed over short time periods (4-6 hours) in comparison with more constant associations at 2 cm below the swface. Both strata had a diverse algal flora (>SO taxa), but no distinct neuston assemblage characterized the surface layer algal composition over the 24-hour study. The similarity between the two strata indicated the floral composition of the surface layer came from the water column algae below the surface. Chlorophytes, diatoms, cyanobacteria, and cryptophytes represented the most abundant algal categories for both strata with a total mean phytoplankton abundance of 3,566 cells mr1 at the surface and 40,532 cells mr1 at 2 cm over the 24 hours. The autotrophic picoplankton had generally similar levels of abundance over time. Their mean abundance for the 24-hours was 469 and 599 x I 03 cells mr1 at the surface and 2 cm respectively. 230 H.G. Marshall. L. Burchardt, E. Wilk-Wozniak INTRODUCTION The surface waters of freshwater and marine habitats represent a dynamic region of the water column. The surface layer and strata directly below the surface are occupied by floral and faunal populations referred to as neuston (Naumann 1917). The fragile nature of this region is under the direct influence of wind action, changing air and water temperatures, variable light intensities, plus water movement occurring within the upper strata of the water column. These and various environmental conditions will influence the composition and abundance of the biota occupying these strata (Marshall, Burchardt 2005). The surface layers of a freshwater pond located in Norfolk, Virginia (U.S.A.) was the habitat under study in this paper. The pond is shallow (ca. 2 m deep), with a surface area of 0.23 ha. In a seasonal study of this pond, Burchardt and Marshall (2003) reported a diverse assemblage of algae within both the surface neuston layer and waters at ca. 40 cm depth, with no unique floral assemblage associated with the neuston. The objectives of this study were to compare phytoplankton composition and abundance, plus autotrophic picoplankton abundance, between the surface layer and waters at 2 cm depth of this pond over a 24-hour period. MATERIAL AND METHODS Water samples were taken on June 8-9, 2004 at four randomly designated stations in the pond, with consecutive collections taken at 2:00 pm, 8:00 pm, 1 :00 am, 5:00 am, and 2:00 pm. The surface neuston samples were obtained following a glass plate collection protocol (Harvey and Burzell 1972), with separate collections for the phytoplankton and autotrophic picoplankton analysis. Sub-surface samples were collected using a 20 ml pippet that was modified so that the lower end of the pippet was bent at a right angle. The pippet was used to obtain water at 2 cm below the surface with the bent region held horizontal to the water's surface, with separate sample sets collected for phytoplankton and autotrophic picoplankton. During each sampling period a minimum of 10 sub-samples were taken at each station and combined for phytoplankton analysis, this procedure repeated to obtain the water for picoplankton analysis. The phytoplankton samples were preserved with Lugol's solution and analyzed using light microscopy at 300X and 600X magnification. The picoplankton was preserved with glutaraldehyde and cell counts determined using epifluorescence microscopy (Burchardt and Marshall 2003). Results from each of the four stations, for each time period, were analyzed separately and the results recorded. Mean values were then determined from data taken at the four Comparison of phytoplankton and autotrophic picoplankton populations ... 23 I stations for each time period. Water quality analysis was conducted using standard analytical methods. RESULTS During the 24-hour study the surface waters and their phytoplankton assemblages were exposed to changing environmental conditions. These included water temperatures at the pond's surface which ranged from 24.0 to 30.0°C and pH from 8.6 to 9.3. Air temperature was from 21.1 to 33.8 ·c and wind velocity 3.2 to 9.7 km h. 1• The pond's surface water chemistry {upper 2 cm) indicated values (mg r1) as: total nitrogen (0.75), total dissolved nitrogen (0.54), total phosphorus (0.05), and total dissolved phosphorus (0.02). 100000 ... 5 10000 1000 100 2pm 8pm lam Sam 2pm Fig. 1. Total phytoplankton abundance comparison (log scale), June 8-9, 2004, for the surface layer (gray) and at 2cm layer (black). Phytoplankton Total phytoplankton abundance in the surface layer fluctuated over the 24-hour period between 527 (1 :00 am) and 7,487 (5:00 am) cells per m1"1 (Fig. 1). In contrast, at 2 cm the total phytoplankton ranged from 31,872 (5:00 am) to 49,478 (1 :00 am) cells mr 1• These concentrations varied over the 24-hours at both the surface and at 2 cm. Mean cell concentrations of total phytoplankton over the 24-hour period were 3,566 cells m1"1 at the surface and 232 H.G. Marshall, L. Burchardt, E. Wilk-Wozniak 40,532 cells mt· 1 for 2 cm (Table 1 ). Chlorophytes were abundant in both layers with mean counts of 2,182 and 13,018 cells mr' for the surface and 2 cm, respectively. The other most common and diverse algae were diatoms. Their mean abundance was 907 and 11,210 cells ml"1 for the surface and 2 cm depth. More abundant and common at 2 cm than in the surface layer were cryptophytes and cyanobacteria with mean concentrations of 9,223 and 6,872 cells ml"1, respectively. The mean concentrations of the total phytoplankton community were 3,566 and 40,562 cells m1" 1 at the surface and 2 cm. In total, there were 57 taxa recorded for the surface layer and 58 taxa at 2 cm. No unique phytoplankton assemblage over the 24-hours was associated with the neuston surface layer. The flora at the surface included taxa present at 2 cm. Representative taxa recorded in the surface layer and at 2 cm are given in Table 2. In addition to these species, small (< 5 microns) unidentified diatoms were common representatives throughout the study in both strata. Table 1 Mean cell concentrations of phytoplankton and autotrophic picoplankton in the pond over 24 hours, June 8-9, 2004. Phytoplankton (cells ml" 1) Surface 2cm Chlorophytes 2,182 13,018 Diatoms 907 11,210 Cryptoohvtes 282 9227 Cvanobacteria 180 6,872 Others 14 239 Total 3,566 40,562 Autotrophic picoplankton (cells mr') 469,000 599,000 The relative abundance relationships among the floral groups are given in Figure 2. At the surface, the chlorophytes represented from 38% to 95% of the flora. Changes in the representation of the major algal categories, and individual taxa, occurred throughout the study. Several of the most common species were Ankistrodesmus fusiformis Corda, Coelastrum cambricum Archer, Cosmarium grantum Breb. ex Ralfs, and Scenedesmus armatus Chodat. The other major surface components were diatoms that included an abundant representation of unidentified centric diatoms and several pennate species. The cyanobacteria, cryptomonads and a category of other algae had decreasing abundance relationships. Many of the most common surface flora were also common taxa at 2 cm. These included the small centric diatoms. The relative abundance Comparison of phytoplankton and autotrophic picoplankton populations... 233 100% · 90% j 80% j 70% 60%, 0cm I 50%' 40% 30% 20% 10% 2pm 8pm lam Sam 2pm 70% 60% 2cm 50% 40% 30% 20% 10% 0% 2pm 8pm lam Sam 2pm Fig. 2. Relative abundance of major algal categories at 0 cm (surface) and 2 cm depth beginning June 8 into June 9, 2004 for chlorophytes (black), diatoms (white), cyanobacteria (diagonal hatch), cryptophytes (gray), and others (vertical hatch). Table 2 Representative phytoplankton taxa from the pond at the surface ;md 2 cm depth, June 8-9, 2004. Surface 2cm Ankistrodesmus fusiformis Corda Actinastrum hantzschii Lagreheim Coe/astrum cambricum Archer Coe/astrum cambrirom Archer Cosmarium 1trantum Breb. ex Ralfs Oocvstis oarva W. ct G.S. West Oocvstis oarva W. et G.S. West Phacotus /enticularis <Ehr. l Stein Phacotus /enticu/aris {Ehr.) Stein Scenedesmus armatus Chodat Scenedesmus armatus Chodat Scenedesmus subsoicatus Chodat Gomohonema oarvulum /Kiltz.) Grunow. Tetraedron muticum (A. Brown) Hans2ir11 Navicula soo Borv Treubaria schmidlei {Schroeder) Fott et Kovac! Nitzschia so Hassal Aulacoseira ambiJtUa (Grun.) 0. MUiier Small centric diatoms, < S microns Au/acoseira 1tranulata (Ehr.) Ralfs Romeria okensis {Meyer) Hindilk Cye/ote/la mene1thiniana Kiltzinl! Microcystis wesenbel1{ii Komarek Gomohonema oarvulum (Kiltz.) Grunow. Merismooedia tenuissima Lemm, Small centric diatoms, <5 microns Trachelomonas superba Swirenko emend. Deflandre Anabaena sp Bory Rhodomonas minuta Skuja Merismouedia tenuissima Lemm. Micr=tis wesen,._,,ii Komarek Romeria okensis (Mever) Hindak Crvotomonas marsonii Skuia Rhodomonas minuta Skuia 234 H.G. Marshall. L. Burchardt1 E. Wilk-Wozniak relationships between the dominant algal categories of chlorophytes, diatoms, cryptophytes, and cyanobacteria at this lower depth had less variability compared to the surface layer. Autotrophic picoplankton The autotrophic picoplankton at both depths were similar in their shape, size, and fluorescence, and consisted predominantly of isolated single cell cyanobacteria <2 microns in size. Their mean concentrations during the study at the surface and 2 cm were 469 and 599 x 103 cells ml"1 respectively. In the surface layer, concentrations ranged from 168 (2:00 pm) to 530 (2:00 pm) x 103 cells mr1• These concentrations were greater at 2 cm with values from 470 (5:00 am) to 835 (8:00 pm) x 103 cells ml"1 (Fig. 3.). 900 7 800 ·1 700 1 I e Goo 1· ~500 · ~ g400 = -= 300 200 100 0 -, 2pm 8pm lam Sam 2pm Fig. 3. Autrotrophic picoplankton abundance within the pond on June 8-9, 2004, for the surface layer (gray) and at 2cm layer (black). DISCUSSION AND SUMMARY The phytoplankton composition in the surface neuston layer was generally similar to the phytoplankton composition at 2 cm below the surface. This supports the premise that subsurface waters are the major source of algae occupying the neuston layer. The changing environmental conditions over this time period indicated a variety of factors that could have influenced the exchange and development of phytoplankton within these strata. In addition, the surface neuston composition exhibited greater shifts in abundance relationships Comparison of phytoplankton and autotrophic picoplankton populations... 235 among the dominant flora over 24 hours than occurred at the 2 cm depth. This was most evident regarding chlorophyte levels of development, and that major differences in algal abundance and the ratios between the different algal categories took place over short time periods. In contrast, the 2 cm depth exhibited less variability between the relative abundance among the algal categories over time, showing that generally comparable relations were maintained over this time period between chlorophytes, diatoms, cryptomonads, and cyanobacteria. The influence of these changing environmental conditions on the phytoplankton composition within these strata decreased rapidly with depth. In summary, both the surface layer and waters 2 cm below the surface contained a diverse and changing assemblage of phytoplankton. There was no distinct assemblage that was unique to the surface (neuston) layer over the 24-hour period. The surface layer's populations included taxa common to flora at 2 cm. The degree of influence that the general daily environmental conditions had on the presence of these algae was greater at the surface compared to the 2 cm depth. The surface populations existed in a thin and fragile layer more directly exposed to the daily environmental conditions that changed during the 24-hour period. These environmental influences resulted in a dynamic and unstable surface environment compared to waters at the 2 cm depth where the phytoplankton composition, abundance relationships, and stability were greater. ACKNOWLEDGEMENTS Special thanks are given to Todd Egerton and Slawomir Cerbin who assisted in collecting. REFERENCES Burchardt, L., Marshall, H. G.. 2003, Algal composition abundance in the neuston surface micro layer from a lake and pond in Virginia (CJ.S.A), J. Limnology, 62(2), 139-142. Harvey, G. W., Burzell, L. A., 1972, A simple micro/ayer method for small samples. Limnol. Oceanogr., 17,156-157. Marshall H.G., Burchardt L., 2005, Neuston: Its definitions with a historical review regarding its concept and community structure. Archiv for Hydrobio/ogie, in press. Naumann, E. 1917,. Beutriige zur Kenntinis der Teichnannoplanktons. 11 Ober das Neuston des Susswassers, Biol. Zentralbl., 37(2),98-106. 

Comparison of Phytoplankton and Autotrophic Picoplankton Populations Over a 24-Hour Period From a Pond\u27s Surface and Subsurface Waters

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Comparison of Phytoplankton and Autotrophic Picoplankton Populations Over a 24-Hour Period From a Pond\u27s Surface and Subsurface Waters

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