1 Diatoms of the Holocene from Poutwater Pond Bog, Holden, MA.Adrienne P. Smyth and Peter M. Bradley Department of Biology, Worcester State College, 486 Chandler St., Worcester, MA 01602, USA. 8,180 years Fig. 3 (left) and 4 (right). The Centrales, Aulacoseira species and one Cyclotella species (fig.4). Identification and dating are denoted in figures. Fig. 3 (left) and 4 (right). The Centrales, Aulacoseira species and one Cyclotella species (fig.4). Identification and dating are denoted in figures. MATERIALS and METHODS A five meter sediment core was collected in the summer of 2005 with a hand driven chamber to a depth of 5 meters. Diatoms were extracted from peat samples by density buoyant centrifugation (Morgenroth et al 2000). One gram of sample was mixed with 2g/ml ZnCl2 solution and centrifuged at 200 X g for 10 minutes. The top layer was passed through a Nalgene 0.2µm filter, washed, air dried, mounted onto carbon tape, and sputter coated with gold for SEM with a JEOL JSM-5600LV microscope. Ten core sediment samples were radiocarbon dated by Geochron Cambridge, MA The data was converted to calendar years before present (CaYBP) using a calibration curve (Fairbanks et al 2005). ABSTRACT Diatoms isolated from a 495 cm core from the Sphagnum peatland surrounding Poutwater Pond, Holden, Massachusetts, were examined by scanning electron microscopy to evaluate their historical colonization of the site and their presence as environmental indicators over the last 8,500 years. Both freshwater centric and pennate diatom species were found. The presence of the centric Aulacoseira and Cyclotella diatom species at the earliest time suggests a planktonic deep water oligotrophic lake environment of low acid neutralizing capacity indicative of peatland initiation. Acidophilic pennate diatom species characteristic of bogs, Eunotia, Pinnularia and Tabellaria were present, in addition to Stauroneis, and Neidium species types. The diatom taxa at this site were similar to other peatlands, but differences in diatom species distribution worldwide may be observable by high resolution picture documentation and identification. Introduction The examination of diatoms preserved in peatlands and lake sediments has attracted many scientific investigation and observations. Diatoms isolated from peatlands have been used as indicators of peatland progression (Rühland et al 2000, Brugam and Swain, 2000), to document climate changes (for review see Smol and Cumming 2000) in the Artic from ice cores (Harwood, 1986) and in investigations comparing limnological changes as a result of anthropogenic or natural activities (Köster and Pienitz 2006). Most have focused on quantitative studies. In contrast, this research is more a qualitative analysis of high resolution documentation. This study found and identified diatom species by scanning electron microscopy from a peat sediment core with a basal radiocarbon date of 8,500 years ago. Planktonic diatom species at the deepest sampling indicate the existence of deeper water with bethnic diatoms distributed throughout the core. This data is presented as a high resolution documentation of some diatom species inhabiting a New England bog during 8,500 years. Diatoms from this study were similar to those reported in Buczkó and Wojtal's (2005) study of algal inhabitants of a Hungarian bog and to the freshwater diatoms found at the base of the Greenland Ice Sheet from the Pleistocene (Harwood 1986). More qualitative studies of this type may permit evaluation of diatom distribution patterns in specific niches worldwide. RESULTS Fig. 1 Depth-age curve. Error bars indicate standard deviation of years or range of sample depth. Fig. 5 (left) and 6 (right). The Pennate Eunotia species. Identification and dating are denoted in figures. SEM RESULTS Fig. 2 Low magnification view of diatoms isolated from 4,450 year old sample. Note large Stauroneis sp at central left of image. Fig. 7 (left) and 8 (right). Pennate species of Neidium, Stauroneis, Tabellaria, Diploneis and Pinnularia. Eunotia Tabellaria flocculosa Aulacoseira Stauroneis THE SITE Massachusetts first National Natural Nature Preserve, Poutwater Pond Bog is located in northern Holden, MA, with coordinates of 42º 25΄ 30˝ North latitude 71º 50΄ 20˝ West longitude on the Sterling quadrangle with an elevation of 700 feet (213 meters). The five meter pond lies within 28 acres (11.33 hectares) of land and is surrounded by a floating bog mat. (Map courtesy of USGS, National Parks Service) Asterionella CONCLUSIONS This research documents Holocene diatoms from a New England bog. Many Eunotia and other acidophilic species were documented at this site. The presence of Cyclotella and Aulacosiera species suggests a open water littoral environment at an early time point. Correlation of similar data may data provide a worldwide diatom distribution pattern for peatlands. The accumulation of peat appears constant and is estimated at 1cm every 20 years. The basal peat date is approximately 8,500 calendar years before present suggesting a time for peatland initiation. As interest in peatlands is expanding with insight into global warming, the importance of documentation and continual monitoring of peatland environments and the biodiversity contained within cannot be understated. References Brugam R.B. & Swain P Diatom indicators of peatland development at Pogonia Bog Pond, Minnesota, USA. Holocene 10,4, Fairbanks, R.G., Mortlock, R.A., Chiu, T-C., Cao, L., Kaplan, A., Guilderson, T.P., Fairbanks, T.W., Bloom, A.L., Grootes, P.M., Nadeau, M-J., 2005. Marine radiocarbon calibration curve spanning 0 to 50,000 years BP based on paired 230Th/ 234U/ 238U and 14C dates on pristine corals. Quat. Sci. Rev. 24, Harwood D.M., Do diatoms beneath the Greenland ice sheet indicate interglacials warmer than present? Artic 39,4, Köster D. & Pienitz R., Late-Holocene environmental history of two New England ponds:natural dynamics versus human impacts. Holocene 16,4, Morgenroth, G., Kersher, H., Kretschmer, W., Klein, M., Reichel, M., Tully, T., Wrzosok, I., Improved sample preparation techniques at the Erlangen AMS-facility. Nuc. Instr. Meth. Phys. Res. 172, Rüland K, Smol J.P., Paul Jasinski J.P., Warner B.G., Response of diatoms and other siliceous indicators to the developmental history of a peatland in the Tiksi Forest, Siberia, Russia. Artic, Antartic, and Alpine Res. 32, Smol J. P. & Cumming B.F., Tracking long-term changes in climate using algal indicators in lake sediments. J. Phycol. 36, Acknowledgements The authors thank Worcester State College for the mini grant award to Dr. P. M. Bradley which was used for carbon dating of the samples by Geochron, Cambridge MA, and Dr. Wyatt Oswald of Harvard Forest.