Paleolimnological records of Didymosphenia geminata in North America. Sarah A Spaulding INSTAAR, University of Colorado

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1 Paleolimnological records of Didymosphenia geminata in North America Sarah A Spaulding INSTAAR, University of Colorado

2 Problem Nuisance blooms of Didymosphenia geminata occur in streams and rivers of the Rocky Mountains, including within national park boundaries. Management responses to Dg depend on whether the diatom is native to the region, or is a recent arrival. The goal of this study is to reconstruct the historical presence of Dg, based on subfossils preserved in lake sediments. In Beauty Lake, we also have the opportunity to examine additional paleolimnological parameters (sediment geochemistry).

3 Live cell of D. geminata, showing chloroplast with dorsal fold. Numerous diatoms (Achnanthidium especially) grow attached to the stalk. Valve of D. geminata, showing large, robust siliceous valve, stigmata and apical porefield

4 Paleo record of stream diatoms in lakes Didymosphenia geminata reaches its greatest abundance in streams and rivers with fairly rapid flow. Cells grow within lakes, primarily the wave zone, but they do not reach high abundance. An ideal study site is a small lake, with quantified Dg blooms upstream. Then, it would be possible to develop a calibration between stream abundance and lake sediment abundance.

5 LOTIC SYSTEMS EROSIONAL HABITAT No preservation of historical record Streams and rivers

6 LENTIC SYSTEMS DEPOSITIONAL HABITAT Preservation of historical record Diatom species in the sediments include those that live in the lake (planktonic + benthic) and those that were deposited by streams. Ponds and small lakes

7 LENTIC SYSTEMS DEPOSITIONAL HABITAT Preservation of historical record Diatom species in the sediments dominated by (planktonic + benthic). Smaller proportion of species deposited by streams. Large lakes

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9 Naknek Lake 800 year record Pite et al. 2009

10 Beauty Lake Yellowstone Lake Phelps Lake

11 Method Sediments were dried, weighed and was digested in 30% H 2 O 2. Ten microslides from each sediment section were made from each sample. ALL Didymosphenia valves were enumerated from the each of the ten microslides at low power (40x).

12 Yellowstone Lake large lake Theriot E.C., Fritz S.C., Whitlock C. and Conley D.J Late Quaternary rapid morphological evolution of an endemic diatom in Yellowstone Lake, Wyoming. Paleobiology 32: National Lacustrine Core Facility (LacCore) core 1A FD2-92, from water depth 81.5 m, cm to 108 cm, 1 cm sections dispersed through core to approx 13,000 ybp based on 14C dates of organic material 177 samples Dg not confirmed Cymbella janischii present

13 Beauty Lake relatively small, subalpine Gravity core obtained in 2007 Total core depth 269 cm Chronology based on 210Pb and 14C Maximum age, at glacial till of 14,930 ybp Dg present (Saros et al., in prep.)

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15 D. geminata valves from Beauty Lake sediments

16 Stone et al., in prep

17 A lake in Maine was transformed from a more productive, high P, high ph, low DOC system into an oligotrophic, relatively low P, acidic, humic lake over a period of 16,600 years.

18 Beauty Lake Fe Speciation µmol Fe / g dry wt BTY 001 BTY 040 BTY 079 BTY 118 BTY 137 BTY 156 BTY 176 BTY 191 Depth (cm) BTY 195 BTY 201 BTY 210 BTY 220 BTY 233 BTY 251 BTY 256 BTY 260 BTY 264 BTY 267 BTY % LOI A (NH4Cl) B (BD) C (0.1M NaOH) D (HCl) E (1M NaOH) LOI

19 Beauty Lake P Speciation µmol P / g dry wt BTY 001 BTY 040 BTY 079 BTY 118 BTY 137 BTY 156 BTY 176 BTY 191 Depth (cm) BTY 195 BTY 201 BTY 210 BTY 220 BTY 233 BTY 251 BTY 256 BTY 260 BTY 264 BTY 267 BTY % LOI A (NH4Cl) B (BD) C (0.1M NaOH) - rp C (0.1M NaOH) - nrp D (HCl) E (1M NaOH) LOI

20 Stone et al., in prep

21 Conclusions 1) Dg formed large populations in a newly deglaciated site (Beauty Lake) within a relatively short period of time (2-3,000 years) 2) Large populations of Dg were present in a new habitat - absent human transport. Dg has the capacity to spread in absence of human vectors. 3) Maximum cell concentrations show a strong relationship to the period of warm, dry climate in the region. 4) Dg was not present in Yellowstone Lake during the same time (to 12,000 ybp) 5) Relation of blooms of Dg to P and Fe in sediments remains inconclusive

22 Acknowledgments Sue O Ney, Grand Teton National Park made this study possible. Jasmine Saros, University of Maine Steve Norton, University of Maine Jeffery Stone, Indiana State University Alex Wolfe, University of Alberta Megan Otu, INSTAAR, University of Colorado Danielle Pite, INSTAAR, University of Colorado Anna Hermann, INSTAAR, University of Colorado Funded by: NPS Rocky Mountain Cooperative Ecosystem Agreement (CESU)

23 Spaulding et al., in prep

24 Beauty Lake Al Speciation µmol Al / g dry wt BTY 001 BTY 040 BTY 079 BTY 118 BTY 137 BTY 156 BTY 176 BTY 191 Depth (cm) BTY 195 BTY 201 BTY 210 BTY 220 BTY 233 BTY 251 BTY 256 BTY 260 BTY 264 BTY 267 BTY % LOI A (NH4Cl) B (BD) C (0.1M NaOH) D (HCl) E (1M NaOH) LOI