Diatom Research ISSN: 0269-249X (Print) 2159-8347 (Online) Journal homepage: http://www.tandfonline.com/loi/tdia20 Freshwater diatoms in the Sajama, Quelccaya, and Coropuna glaciers of the South American Andes D. Marie Weide , Sherilyn C. Fritz, Bruce E. Brinson, Lonnie G. Thompson & W. Edward Billups To cite this article: D. Marie Weide , Sherilyn C. Fritz, Bruce E. Brinson, Lonnie G. Thompson & W. Edward Billups (2017): Freshwater diatoms in the Sajama, Quelccaya, and Coropuna glaciers of the South American Andes, Diatom Research, DOI: 10.1080/0269249X.2017.1335240 To link to this article: http://dx.doi.org/10.1080/0269249X.2017.1335240 Published online: 17 Jul 2017. Submit your article to this journal Article views: 6 View related articles View Crossmark data Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=tdia20 Download by: [Lund University Libraries] Date: 19 July 2017, At: 08:18 Diatom Research,2017 https://doi.org/10.1080/0269249X.2017.1335240 Freshwater diatoms in the Sajama, Quelccaya, and Coropuna glaciers of the South American Andes 1 1 2 3 D. MARIE WEIDE ∗,SHERILYNC.FRITZ,BRUCEE.BRINSON, LONNIE G. THOMPSON & W. EDWARD BILLUPS2 1Department of Earth and Atmospheric Sciences, University of Nebraska-Lincoln, Lincoln, NE, USA 2Department of Chemistry, Rice University, Houston, TX, USA 3School of Earth Sciences and Byrd Polar and Climate Research Center, The Ohio State University, Columbus, OH, USA Diatoms in ice cores have been used to infer regional and global climatic events. These archives offer high-resolution records of past climate events, often providing annual resolution of environmental variability during the Late Holocene. Recently, the first low-latitude tropical diatoms were described from the Quelccaya Summit Dome. Here, we document diatoms observed in ice cores from Quelccaya, spanning AD 1300 to 1815, along with those from two additional glaciers (Coropuna, and Sajama glaciers) in the tropical Andes, spanning AD 1764 to 1814. Diatom assemblages recovered from these three sites were rare, but differ in abundance and species composition through time. Assemblages are characterized by cosmopolitan and aerophilic species, mostly pennate diatoms. There were 44 taxa in all, with Pinnularia cf. borealis Ehrenberg being the most common species encountered in the samples. Eleven taxa were found at all three sites. Both Coropuna and Sajama had taxa that were unique to these locations, whereas Quelccaya had no unique taxa. Due to the rarity of diatoms and the cosmopolitan nature of the dominant species, it is not possible to determine their origin, limiting their utility in paleoclimate reconstructions. Keywords: ice cores, tropical Andes, aerophilic diatoms, bacillariophyceae, Pinnularia borealis Ehrenberg, dust transport Introduction Recent research has shown that, at least in some cases, Ice cores from the Eastern and Western Cordilleras of the there are limits to the dispersal of microorganisms and that tropical Andes offer insights into past climate and envi- the distribution of microbes is influenced by both historical ronments (Thompson et al. 1985, 1986, 2013,Liuetal. events and environmental conditions (Martiny et al. 2006). 2007, Herreros et al. 2009, Reese et al. 2013). Particulate The factors that affect the dispersal of diatoms under dif- matter preserved in dust layers in these ice cores includes ferent scenarios are still uncertain, but aeolian-distributed diatoms (Thompson et al. 1994, Fritz et al. 2015), which diatoms can increase our understanding of dispersal mech- may provide clues to climatic patterns in the southern anisms. For example, Van Eaton et al. (2013) demonstrated hemisphere, environmental dynamics associated with the that diatoms in tephra deposits originated from ancient accumulation of the ice, as well as information on microor- Lake Huka, New Zealand, and had become incorporated ganismal dispersal mechanisms across extreme barriers into the ash plume as the volcano erupted through the like the Andes. lake bed. These diatoms were dispersed hundreds of kilo- Wind has long been known to distribute dust and metres from the source, but it is still unclear whether associated microscopic particles, which include pollen they would have been viable once deposited in their new and microorganisms, long distances (Harper 1999, Finlay environment. 2002). Aeolian deposition of diatoms in ice cores from There are still questions on the utility of the diatoms polar areas, including Greenland and Antarctica, is well found in ice cores as proxies for paleoenvironmental documented (Burckle et al. 1988,Gayleyetal.1989, reconstruction and biogeographical studies. Diatoms are Donarummo et al. 2003). In addition, aeolian-deposited ararecomponentofdustcollectedinatmospherictraps diatoms have been used as environmental proxies. Pokras (Harper & McKay 2010), and, thus, may not be useful &Mix(1985)usedfreshwaterdiatomsfromdeep-seased- as proxies of past environment and climate. In addition, iments to track long-term climate variability in tropical diatoms found in previous ice core studies (Donarummo Africa since the Last Glacial Maximum. et al. 2003,Harper&McKay2010, Fritz et al. 2015)are *Corresponding author. E-mail: [email protected] (Received 29 January 2017; accepted 11 April 2017) ©2017TheInternationalSocietyforDiatomResearch 2 Marie Weide et al. Fig. 1. Map of the study area. mostly cosmopolitan aerophilic species, which may limit Cordilleras in the Central Andes (66–71°W, 14–22°S, their utility as indicators of dispersal. 3650–3900 m a.s.l.), covering parts of Peru, Bolivia, ∼ We used diatoms found in ice cores from three sites, Argentina, and Chile (Argollo & Mourguiart 2000), with two on the western boundary and one on the eastern bound- agradientofdecreasingprecipitationfromnorthtosouth ary of the Altiplano, to explore the utility of diatoms within (Condom et al. 2004). The Central Andes are characterized tropical ice cores as indicators of past climate and environ- by steep elevational gradients, with the western slopes on ment, as well as whether they can provide information on the Pacific Coast having a steeper gradient than the east- the likely source region of the diatoms. This study builds ern slopes. Cold-water upwelling in the Pacific results in on a preliminary report on diatoms observed in the Quel- cool sea-surface temperatures and aridity on the western ccaya ice core (Fritz et al. 2015)anddiscussesdiatoms slopes (Zhou & Lau 1998). The Eastern Central Andes are found in two additional ice cores, Nevado Sajama and located adjacent to the relatively wetter Amazon lowlands. Nevado Coropuna. The dominant source of precipitation for the Central Andes is the Atlantic Ocean via the Amazon Basin (Baker et al. 2001). Site descriptions Nevado Coropuna (15°33′S72°39′W, 6450 m a.s.l.), The glaciers included in this study are located in the trop- located 155 km NW of Arequipa, Chile, is an inac- ∼ ical Andes of Peru and Bolivia (Fig. 1). The Andean tive volcano in the Cordillera Ampato (Zagorodnov et al. cordillera is a volcanic arc that is located on the west- 2005), on the western boundary of the Altiplano (Kuentz ern edge of South America, extending from the western et al. 2007). Its area was 60.8 km2 in 2000 (Racoviteanu border of Venezuela down the Pacific coast to Patagonia et al. 2007). Precipitation is mainly from the east, with air at the southern tip of Argentina. Due to their height, the masses originating in the tropical Atlantic Ocean, although mountains obstruct atmospheric circulation of air masses infrequent air masses from the Pacific and southern South between the Pacific and Amazon lowlands (Garreaud et al. America can also affect this site. The majority ( 70–90%) 1 ∼ 2003). The large internally drained basin known as the of annual precipitation ( 700 mm yr− )fallsduringthe ∼ Altiplano is located between the Eastern and Western austral summer (December through March) (Herreros et al. Freshwater diatoms in the Sajama, Quelccaya, and Coropuna glaciers 3 Table 1. Ice core samples analysed in this study. Volume of Total valves Site and sample ID Core depth (m) Age (AD) water (mL) observed Valves/100 mL Coropuna CCC111.74 111.74–111.85 1811 145 6 4.1 CCC113.12 113.12–113.23 1801 150 262 174.7 CCC117.68 117.68–117.81 1766 155 23 14.8 Quelccaya QSD97.49 97.49–97.64 1813 145 20 13.8 QSD98.98 98.98–99.09 1802 160 38 23.8 QSD103.59 103.59–103.77 1764–1765 155 30 19.4 QSD136.40 136.40–136.56 1410–1414 170 18 10.6 QSD138.65 138.65–138.88 1361–1366 160 11 6.9 QSD141.11 141.11–141.30 1306–1311 200 27 13.5 Sajama SJ51.99 51.99–52.14 1814 160 29 18.1 SJ53.30 53.30–53.43 1799 145 164 113.1 SJ55.90 55.90–56.15 1764 190 175 92.1 2009). The dry season is short, lasting June through August small plants, especially Plantago, and shrubs, including (Brack & Mendiola 2000). The average annual tempera- Polylepis (Reese & Liu 2002). ture is < 6°C (Kuentz et al. 2007). The local vegetation is characterized by puna brava, a high-elevation environ- ment with sparse vegetation. It is composed of mainly Materials and methods Apiaceae (Azolla) and Asteraceae, with common occur- The diatom samples presented here were taken from ice rences of marshes and peat bogs in glacially shaped valleys cores recovered in 2003 from the Quelccaya Summit Dome (Kuentz et al. 2007, 2011). (QSD) (Zagorodnov et al. 2005, Fritz et al. 2015), the Nevado Sajama (18°06′S68°53′W, 6542 m a.s.l.), an Sajama Ice Cap (SJ) in 1997 (Hong et al. 2004,Liuetal. extinct volcano in the relatively dry Western Cordillera 2005), and the Coropuna Ice Cap (CCC) in 2003. Sam- of Bolivia, approximately 150 km south of Lake Titicaca, ples for diatom analysis were chosen based on dust layers is near the Chilean-Peruvian border (Vuille 1999,Liu thick enough to be seen without a microscope, maximizing et al.