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Microscopic Past of Poutwater Pond
Adrienne P. Smyth and Peter M. Bradley

Northeastern Naturalist, Volume 16, Issue 4 (2009): 595–606

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2009 NORTHEASTERN NATURALIST 16(4):595–606 Microscopic Past of Poutwater Pond Adrienne P. Smyth1 and Peter M. Bradley1,* Abstract - Poutwater Pond Bog is a National Natural Landmark located in Holden, MA. As present-day species inhabiting this bog have been described, this study presents an insight into earlier inhabitants of the area during the mid- to late Holocene. A 5-m coring of peat was collected 10 m from the pond edge. Radiocarbon analysis of 10 sections of the core shows a nearly linear accumulation rate of peatland from 8500 years ago to the present. The presence of mineral matter at the base of the core suggests paulidification as the mechanism for formation of the bog. Microfossils were isolated from sections of the peat core by densitybuoyant centrifugation, and examined using a scanning electron microscope. High-resolution images of pollen, sponge remains, and algae are presented. Circumneutral and acidobiontic diatoms were found at different depths of the core, indicating a changing water environment over time. Arboreal pollen grains were documented spanning 8500 years of vegetative history, permitting insight into the biodiversity that once existed. Introduction Peatlands preserve a record of environmental history. Pollen from the vegetation and the surrounding landscape of a peatland are preserved in the upper layer of peat sediment. Initial peat growth can be approximated at 1 cm per year, although 90% of this is compacted (Lagerås 2003). Examination of a sediment core of 1 m potentially contains 100–1000s of years of paleoecological data, in the form of radiocarbon dating and analysis of microfossils, some of which is presented here. Peatland development results from either terrestrialization, filling in of a lake or water body, or paulidification, a result of an increase in the water table that triggers peat growth on solid ground inhibiting water drainage. In an examination of three peatlands in New England, it was determined that topographical influences and paulidification were instrumental in their formation (Anderson et al. 2003). A determination of the mechanism of peatland initiation can be inferred by examination of the core for lake mud or silt beneath the peat, indicating terrestrialization in contrast to paulidification, which would have mineral deposits directly underneath the peat (Anderson et al. 2003). Therefore, a single coring may provide insight into peatland development. Classification of bogs can be based on water source or supply, surrounding landforms causative of bog development or landform produced 1Department of Biology, Worcester State College, 486 Chandler Street, Worcester, MA 01602-2597. *Corresponding author - peter.bradley@worcester.edu. 596 Northeastern Naturalist Vol. 16, No. 4 by the bog (Damman and French 1987), or by the presence of vegetative indicator species (Popp 1997). Poutwater Pond Bog has been classified as a “quaking bog” and “an early stage ombrotrophic mire” (Schofield 1971). Favour (1971) agrees with this classification due to its sphagnum coverage, ericaceous shrubs, coniferous trees, and other indicator species. This site has also been described as an “undisturbed sphagnum-heath bog” (USDOI NPS 2001), and a level bog (BioMap and Living Waters 2004, Salett 2002). The US Department of the Interior, National Parks Service (2001) describes Poutwater Pond as an “excellent example of ecological succession from open water in a glacial depression to upland forest.” Poutwater Pond’s acidic water and vegetation are all indications of an ombrotrophic bog or mire; however, the water supply from an ombrotrophic bog is exclusively from precipitation (Damman and French 1987), and the surface water runoff from the surrounding uphill landscape must contribute some nutrients and minerals and as such should be considered a minerotrophic, topogenous peat bog lake system of the moat bog type (Salett 2002). Analysis of microfossils preserved in a bog can provide much paleoecological data. Pollen analysis from sediment was first recorded by Swedish geologist Lennart von Post in the early 1900s (West 1971). An analysis of pollen in increasing depths of sediment can provide a history of vegetation from a time when glaciers covered the land to the present. Shuman et al. (2004) provide an analysis of regional forest development in New England, by comparison of pollen abundance to moisture availability and temperature for the past 15,000 years. Diatoms, unicellular algae, are also useful ecological indicators as they are sensitive to temperature, pH, conductivity, and salinity and exhibit species-selectivity for habitats depending on climate (Smol and Cumming 2000). Diatom assemblies have been used to track the development of a bog from an open-water environment to a raised bog over 7200 years (Rüland et al. 2000). This research aimed to discover the age and depth of the peatland of Poutwater Pond Bog, determine the timeline of peatland development, isolate microfossils for qualitative scanning electron microscopy, and identify microfossils to a species level for subsequent analysis as proxies of environmental change and quantitative analyses. Our preliminary paleoecological findings result from a 5-m core collected in the fall of 2005, from the bog mat at the edge of Poutwater Pond. Radiocarbon dating provides a timeline for approximately the last 8500 years. In another study using this core, bacteria have been isolated and identified (Fynan et al. 2009). Images of microfossils produced by scanning electron microscopy provide insight into the biological diversity of the historic past and allows for identification to species level. Diatoms can be used to determine changes in peatland development, and arboreal pollen dispersed within cores can indicate past climatic changes. 2009 A.P. Smyth and P.M. Bradley 597 Site Description Poutwater Pond Bog is located in northern Holden, MA, with coordinates of 42º25΄30˝N, 71°50´20″W on the Sterling quadrangle (Fig. 1). It is an 11.33-ha (28-acre) site with an elevation of 213 m (700 ft). The 2-ha (5-acre) pond is surrounded by a floating sphagnum bog mat of 6–30 m (20–100 ft). It has also been known as Wonketopick or Rutland Pond. Wonketopick is most likely the Nipmuc “Wonchatopek” or “Wonketopic” meaning “Pond, where to get roots” or “crooked roots place” (NIAC 1995). This etymology Figure 1. Map showing the location of Poutwater Pond, Holden, MA. Map courtesy of The National Natural Landmarks Program, National Park Service. 598 Northeastern Naturalist Vol. 16, No. 4 is supported by the observed presence of Sagittaria latifolia Willd. (Broadleaved Arrowhead or Wapato), which was most likely harvested for its underwater edible tubers by Native Americans (Darby 1996), in the shallow waters surrounding the floating bog mat. In 1971, the site was nominated by Ed Schofield and subsequently evaluated and recommended by Paul Favour for designation as a National Natural Landmark, which was awarded in 1972. In 1994, the Metropolitan District Commission (MDC) purchased 200 ha (493 acres) of which 86 ha (213 acres) includes Poutwater Pond and its surrounding peatland, for watershedprotection purposes. A subsequent evaluation (O’Conner et al. 1997) of Poutwater Pond’s unique geographical makeup, the kettlehole depression, soil variation, esker, and plant communities prompted its nomination as Massachusetts’ first Nature Preserve and designation as such in 1998. The 90.7-ha (224-acre) nature preserve is jointly owned by the Department of Fisheries and Wildlife and the MDC. In 1999, an inventory of vascular plants at Poutwater Pond described 76 plant species in 56 genera and 34 families (Searcy and Hickler 1999). The pond is surrounded by a floating bog mat on which dwarf and tall shrubs infiltrate. On the westerly side, the peatland is wider and the slope to upland more gradual. Typical bog plants are found in the peatlands of Poutwater Pond. These include the families Cyperaceae (sedges), Orchidaceae (orchids), and Ericaceae (the heath family—e.g., rhododendron, azalea, blueberry, and cranberry bushes). Trees that are able to root and grow in bog-like conditions are found in Poutwater, including Picea mariana P. Mill (Black or Bog Spruce), Larix laricina (DuRoi) K. Koch, (Tamarack or American Larch), and Acer rubrum L. (Red Maple). Methods Sediment coring at a location 10 m from the open edge of Poutwater Pond was done with a Russian Peat Corer. The corer was pushed into the ground with the chamber open to the desired depth. It was then twisted 180º clockwise, trapping the sediment within the chamber. The corer was then withdrawn, and the sediment sample retrieved by turning the chamber counterclockwise. Sediment was collected every 50 cm, to a maximum depth of 5 m with the use of extension rods. The samples were covered in plastic wrap and aluminum foil and stored at 4 °C until subsequent sectioning into 5- to15-cm samples for pollen extraction, microscopic analysis, and radiocarbon dating (Smyth 2006). Microfossils were extracted by modification of a density-buoyant centrifugation method developed by Morgenroth et al. (2000). One gram of wet sediment sample was added to 5 ml of ZnCl2 (2 g/ml), vortexed, and centrifuged for 10 minutes at 400 g. Microfossils were collected from the lighter organic top layer onto a Nalgene 0.2-μm filter, and washed with 50 ml 2009 A.P. Smyth and P.M. Bradley 599 of water. The filter was removed and air dried. Microfossils were collected from the filter onto double-stick carbon tape on 8-mm mounting stubs, gold coated using an Anatech Hummer 6.2 sputter coater following the manufacturers instructions, and examined with a JEOL JSM - 5600LV scanning electron microscope (SEM) (Smyth 2006). Radiocarbon dating was performed by Geochron Laboratories, Billerica, MA on 10 samples. Nine samples were processed using 30 g of peat sediment treated with 1M hot HCl for 1 h, followed by drying and combustion in oxygen to generate CO2 for the analysis. The basal age was determined by accelerated mass spectrometry. The age is referenced to the year A.D. 1950. The 14C data obtained was then input into 2 calibration programs for conversion into calibrated years before present (ca BP) using the programs of Fairbanks et al. (2005) and Ramsey’s OxCal 4 (Bronk 1995). Identification of pollen and diatoms from 13 core sections was done by comparison to the online keys of PalDat (Buchner and Weber 2000), USDAARS (2001), and ADIAC (2006) in addition to consulting the literature of Wodehouse (1965), Krammer and Lange-Bertalot (1986), Bassett et al. (1978), Camburn and Charles (2000), and Faegri and Iversen (1989). Results Figure 2 plots 10 uncalibrated and 9 calibrated samples from sections of the core that were radiocarbon dated. The most recent sample extends Figure 2. Radiocarbon dating of the peat core from Poutwater Pond showing the relationship between depth and age. Error bars are standard deviation in years, and range of sediment sampled in cms. 600 Northeastern Naturalist Vol. 16, No. 4 outside the range of both calibration programs (Bronk 1995, Fairbanks et al. 2005) and is omitted from the calibrated data in the figure. The two calibration programs have similar plots; however, a notable difference of approximately 1000 years is observed between the raw 14C date and either of the calibrated dates for the oldest sample. The basal dating of peatland initiation at the site is approximately 8500 ca BP. Paulidification is the inferred mechanism of peatland initiation from the observation of mineral deposits, which lack any lake silt or mud and which have peat deposits immediately above, at the basal depth of the 5-m core collected 10 m from the lake margin of Poutwater Pond. However, further coring is needed to confirm this preliminary evidence for paulidification at this site. There was no observed change in the peat appearance of the core over time except the presence of the additional mineral matter at the base. The peatland accumulation rate is estimated to be between 0.5–0.58 mm/yr. As mineral matter impeded deeper sample collection, this result is only suggestive and warrants further coring closer upland. Visualization of the isolated microfossils by scanning electron microscopy has resulted in many collected and stored images, a few of which we present in this paper (Figs. 3–5). Figure 3 is a low-magnification image Figure 3. Scanning electron microscope (SEM) images of 4500 ca BP sample containing pollen, diatoms, and sponge remains. (a) pine and (b) alder pollen, (c) sponge spicule, (d) sponge gemmosclere, (e) centric diatom, and (f) pennate diatom. 2009 A.P. Smyth and P.M. Bradley 601 Figure 4. Freshwater microfossils as examined with the SEM. Ages of samples are in brackets in ca BP. (a) Cyclotella sp., a centric diatom (8250), (b) Eunotia sp., a pennate diatom (3800), (c) Aulacoseira sp., a centric diatom (5400), (d) unidentified Dinoflagellate (3800), and (e) Eunotia glacialis F. Meister, a pennate diatom (5400). captured by SEM of isolated pollen, sponge spicules, and diatoms from 4500 ca BP, demonstrating a good recovery and specimen isolation using the outlined methodology. Higher magnification and resolution by SEM (Figs. 3–5) aids species identification of microfossils using morphological distinctions. Centric and pennate diatoms were found at all depths sampled. Although many diatom species have been identified, only a few are shown in Figures 3 and 4 as examples. Other microfossils isolated include freshwater sponge spicules and gemmoscleres, and dinoflagellates (Figs. 3c, 3d, and 4d). Arboreal pollen was found throughout the core, and representative images of Pinus (pine), Carya (hickory), Tsuga (hemlock), Betula (birch), Salix (willow), Alnus (alder), Fagus (oak), and Acer (maple) are shown in Figure 5. Pinaceae family and Fagaceae pollen were found throughout the depth of the core. The more temperate species of hickory, willow, and maple were found at depths central to the sediment sampling, from 246 to 325 cm, and dated around 3–6000 ca BP; these were not as abundant as pine and oak species. Non-arboreal pollen of Alismaceae, plant members of which are found 602 Northeastern Naturalist Vol. 16, No. 4 in ponds and streams, was found in the most recent deposition of peat, dating less than 125 BP, but at no other depth sampled. As BP refers to dates before 1950, this is a time in the early 1800s. Figure 5. Pollen isolated from different depths of peat: SEM images. Ages of samples are in brackets in ca BP. (a) American Water-plantain (<125), (b) pine on left and hickory on right (4000), (c) hemlock on left and birch on right (7250), (d.) maple at top and Aulacoseira sp. on bottom (7250), (e) alder (4500), (f) oak (8500), and (g) willow (4500). 2009 A.P. Smyth and P.M. Bradley 603 Discussion Peatlands, in addition to preserving a record of biological diversity, are becoming more important as climate-change studies are increasing in significance and attention. Peatlands are a carbon sink, and as such, scientists differ in their opinions as to whether the demise of peatlands by elevating temperatures would result in them becoming a carbon source or remaining as a carbon sink by the initiation of new forest cover. Some literature suggests the accumulation of peat has begun to slow down in the West Siberian Lowland and that these areas have been methane sources since the early Holocene (Smith et al. 2004). Our data of a New England temperate peatland provide evidence of its existence since 8500 ca BP, which compares to 3 other peatlands in New England that have been dated at 7250, 8420, and 9600 ca BP, respectively (Anderson et al. 2003). The accumulation rate of peat over time at Poutwater Pond of 0.5–0.58 mm/yr does appear to lag during more recent times, but this interpretation is not conclusive and falls within the data presented from the three previously mentioned New England peatlands. Analysis of the diatom data suggests a changing lake environment. Cyclotella and species of other diatom genera of low acid-neutralizing capacity were found at the deeper sampling depths and are indicative of a deep-water oligotrophic lake environment prior to or during the early stages of peatland initiation. Acidophilic or acidobiontic species of diatoms (e.g., Eunotia and Aulacoseira) are found as time progresses, the sphagnum peatland accumulates, and the water chemistry is altered and becomes more acidic (Brugam and Swain 2000). General climate trends during the time of initiation at the site approximately 8500 ca BP are associated with a change from a warm, dry to a cooler, wetter climate suitable for the accumulation of peatland species (Davis et al. 1980). Vegetative pollen recovered is mainly from tree species (Figs. 5 b–g). Pine, hemlock, and oak pollen were found at 8500 ca BP, suggesting a thriving forest landscape. Hickory, birch, and maple pollen grains were identified between 4–7400 ca BP. The most infrequently encountered pollen was willow, at 4500 ca BP, followed by alder. The observation of pollen from the more temperate tree species during the mid-Holocene agrees with a warming after 8200 ca BP and with moisture availability decreasing until 3000 ca BP (Shuman et al. 2004). The non-arboreal Alisma plantago L. (Water Plantain) pollen (Fig. 5a) may be indicative of more recent human influences. Native Americans may have cultivated this edible plant in addition to the presentday Arrowhead found in the shallow waters of the moat adjacent to the floating bog mat. Freshwater sponges and dinoflagellates (Fig. 4) were also a part of this habitat, as evidenced by sponge spicules and gemmoscleres (Fig. 3), and their presence is in agreement with the ending of a drier climate trend of 604 Northeastern Naturalist Vol. 16, No. 4 the Holocene and the beginning of a modern cooler and wetter climate trend around 3200 ca BP (Newby et al. 2000). This study, derived from the preliminary analysis of microfossils and radiocarbon dating, of a coring from the peatlands of the National Natural Landmark and Massachusetts’ first Nature Preserve, Poutwater Pond Bog, Holden, MA, presents a timeline for peatland initiation and provides insight into the palynological diversity during the Holocene (Figs. 3–5); our results offer evidence for changing climate trends spanning approximately 8500 years. Acknowledgments The authors are grateful to the Worcester State College faculty mini-grant program for financial assistance to obtain the radiocarbon data. We thank Wyatt Oswald of Harvard Forest for assistance with pollen identification and core sampling. We are also grateful to the guest editor, Dr. G.A. Langlois, and the reviewers for many valuable suggestions that improved the manuscript. Literature Cited Anderson, R.L., D.R. Foster, and G. Motzkin. 2003. Integrating lateral expansion into models of peatland development in temperate New England. Journal of Ecology 91:68–76. Automatic Diatom Identification and Classification (ADIAC). 2006. Available online at http://www.ualg.pt/adiac/intro/general.htm. Accessed April 12, 2006. Bassett, I.J., C.W. Crompton, and J.A. Parmelee. 1978. An Atlas of Airborne Pollen Grains and Common Fungus Spores of Canada. Canadian Department of Agriculture Monograph No. 18. Ottawa, ON, Canada. 321 pp. BioMap and Living Waters. 2004. Guiding land conservation for biodiversity in Massachusetts. Core habitats of Holden. Produced by Natural Heritage and Endangered Species Program, MA Division of Fisheries and Wildlife, Westborough, MA. Bronk, R.C. 1995. Radiocarbon calibration and analysis of stratigraphy: The OxCal program. Radiocarbon 37(2):424–430. Brugam, R.B., and P. Swain. 2000. Diatom indicators of peatland development at Pogonia Bog Pond, Minnesota, USA. Holocene 10(4):453–464. Buchner, R., and M. Weber. 2000. PalDat. A palynological database: Descriptions, illustrations, identification, and information retrieval. Available online at http:// www.paldat.org/. Accessed 27 September 2005. Camburn, K.E., and J.C. Charles. 2000. Diatoms of Low-alkalinity Lakes in the Northeastern United States. The Academy of Natural Sciences of Philadelphia, Philadelphia, PA. 152 pp. Damman, A.W.H., and T.W. French. 1987. The ecology of peat bogs of the glaciated northeastern United States: A community profile. US Fish and Wildlife Service, Washington, DC. Biological Report 85(7.16). Darby, M.C. 1996. Wapato for the people: An ecological approach to understanding the Native American use of Sagittaria latifolia on the lower Columbia River. M.A. Thesis. Portland State University, Portland, OR. 136 pp. 2009 A.P. Smyth and P.M. Bradley 605 Davis, M.B., R. Spear, and L. Shane. 1980. Holocene climate of New England. Quaternary Research 14:240–250. Faegri, K., and J. Iversen. 1989. Textbook of Pollen Analysis. 4th Edition. John Wiley and Sons, Chichester, UK. 328 pp. Fairbanks, R.G., R.A. Mortlock, T.-C. Chiu, L. Cao, A. Kaplan, T.P. Guilderson, T.W. Fairbanks, and A.L. Bloom. 2005. Marine radiocarbon calibration curve spanning 0 to 50,000 years BP based on paired 230Th/ 234U/ 238U and 14C dates on pristine corals. Quaternary Science Review 24:1781–1796. Favour, P.G. 1971. Evaluation of Poutwater Pond Bog Holden, Massachusetts for eligibility for registered national landmark. National Parks Service, US Department of the Interior, Washington, DC. Fynan, E.F., M.R. Hunt, P. Dowling, J. Auguste, P. Smyth, and P.M. Bradley. 2009. Natural antibiotic resistance of bacteria isolated from a peat bog at Poutwater Pond, Holden, MA. BIOS - Quarterly Journal of Biology 80(1):9–13. Krammer, K., and H. Lange-Bertalot. 1986. Bacillariophyceae. Parts 1–4. In H. Ettl, J. Gerloff, H. Heynig, and D. Mollenhauer (Eds.). Volume 2 of Süsswasserflora von Mitteleuropa. Gustav Fischer Verlag: Stuttgart, Germany. Lagerås, P. 2003. Approaches and methods for commissioned archaeology in wetlands: Experience from the E4 project in Skåne, southern Sweden. European Journal of Archaeology 6(3):231–249. Morgenroth, G., H. Kersher, W. Kretschmer, M. Klein, M. Reichel, T. Tully, and I. Wrzosok. 2000. Improved sample-preparation techniques at the Erlangen AMSfacility. Nuclear Instruments and Methods in Physics Research 172:416–423. Newby, P.E., P. Killoran, M.R. Waldorf, B.N. Shuman, R.S. Webb, and T.S. Webb. 2000. 14,000 years of sediment, vegetation, and water-level changes at the Makepeace Cedar Swamp, Southeastern Massachusetts. Quaternary Research 53:352–368. Nipmuc Indian Association of Connecticut (NIAC). 1995. Historical Series, Number 3, 1st Edition, 1995. Nipmuc Place Names of New England. Available online at http://www.nativetech.org/Nipmuc/placenames. Accessed 26 April 2006. O’Conner, R., K.B. Searcy, T. Mahlstedt, D. Clark, G. Buzzell, T. Simmons, and J. MacDougall. 1997. Poutwater Pond Nature Protection Plan. Report produced by Metropolitan District Commission (MDC) from the Nature Preserve Program of the Department of Fisheries and Wildlife Boston, MA. Popp, R.G. 1997. Lakes, ponds, bogs, and fens. New England Wildflower 1:22–24. Rüland, K., J.P. Smol, P. Jasinski, and B.G. Warner. 2000. Response of diatoms and other siliceous indicators to the developmental history of a peatland in the Tiksi Forest, Siberia, Russia. Arctic, Antarctic, and Alpine Research 32:167–178. Salett, M. 2002. A natural history of bogs and acidic fens of southern New England. Conservation Perspectives (on-line journal of the NESCB). Available online at http://www.nescb.org/epublications/summer2002/bogsand fens1.html. Accessed 14 June 2005. Schofield, E. 1971. Description of Poutwater Pond, Holden, Massachusetts. Attachment to: Poutwater Pond Bog, Nature Preserve Nomination Form. Massachusetts Division of Fisheries and Wildlife, Boston, MA. Searcy, K.B., and M.G. Hickler. 1999. The peatland communities and vascular flora of the peatland within Poutwater Pond Nature Preserve. Rhodora 101:341–359. 606 Northeastern Naturalist Vol. 16, No. 4 Shuman, B., P. Newby, Y. Huang, and T. Webb III. 2004. Evidence for the close climatic control of New England vegetation history. Ecology 85:1297–1310. Smith, L.C., G.M. MacDonald, A.A Velichko, D.W. Beilman, O.K. Borisova, K.E. Frey, K.V. Kremenetski, and Y. Sheng. 2004. Siberian peatlands a net carbon sink and global methane source since the early Holocene. Science 303:353–356. Smol, J.P., and B.F. Cumming. 2000. Tracking long-term changes in climate using algal indicators in lake sediment. Journal of Phycology 36:986–1011. Smyth, A.P. 2006. Scanning electron microscope study of present-day pollen and microfossils of Poutwater Pond Bog, Holden, Massachusetts. M.Sc. Thesis. Worcester State College, Worcester, MA. 95 pp. US Department of Agriculture (USDA-ARS). 2001. Areawide Pest management Research Unit. Available online at http://www.pollen.usda.gov. Accessed 27, September 2005. US Department of the Interior (USDOI-NPS). 2001. National Natural Landmarks Program of the National Parks Service, Boston, MA NNL file 1962-2001: group 79. West, R.G. 1971. Studying the Past by Pollen Analysis. Oxford University Readers. Edited by J.J. Head and O.E. Lowenstein. Oxford University Press, London, UK. 16 pp. Wodehouse, R.P. 1965. Pollen Grains: Their Structure, Identification, and Signifi- cance. Hafner Publishing Company, New York, NY. 574 pp.