South American diatoms: a hidden gem with enormous potential

*This is the dedicated post of the Diatom of the Month-January 2018 blog series

The South American continent was crucial to inspire Charles Darwin´s Origin of Species. During his travel, Darwin recognized the importance of two factors while developing his famous theory on how nature works: biogeography and history. In Darwin’s words:

When on board H.M.S. Beagle, as naturalist, I was much struck with certain facts in the distribution of the inhabitants in South America, and in the geological relations of the present to the past inhabitants of that continent”.

Professor Christian Ehrenberg was the first to analyze diatoms from South America, in the Tierra del Fuego. Darwin was fascinated by Ehrenberg´s microscopic observations of diatoms in diatom-rich geological deposits (diatomite). Due to the old age of such deposits and known diatom forms identified, Darwin thought that diatom distributions should also be old, and probably having wide geographical distributions due to their presence in that extreme region of Earth. Therefore, the very first studies of South American diatoms, back in the 19th century, appear to be strongly related to historical biogeography, which is nowadays a hot topic in microbial biogeography discussions (Williams, 2011).

Figure 1. Ehrenberg’s original drawings of microorganisms, including diatoms, from Tierra del Fuego (Source: Williams, 2011).

Since then, however, South American diatom diversity has never been thoroughly investigated. Despite the difficulty in studying high-elevation waterbodies due to topographic and climatological extreme conditions, the Andes mountains became the focus of the first diatom studies. The first floristic descriptions were made in the 1920s by Hustedt in Chile (1927), followed by Frenguelli (1930-1940) in Argentina, and Manguin (1964) in Perú. However, despite the scientific interest of a variety of aquatic ecosystems in the Andes for studies on the diversity of diatoms and their use as ecological indicators (e.g. in paleoclimatology), later diatom studies are surprisingly scarce in this region.

Two major monographs were recently published by Rumrich et al. (2000) and Metzeltin & Lange-Bertalot (2007) in the Andes (Figure 1), and adjacent Amazon lowlands (Figure 2), respectively. According to these authors, the Amazon lowlands contain much more endemisms (diatom species unique to a region) than Andean waterbodies, the latter characterized by more numerous cosmopolitan species. The idea that Andean diatoms have a high proportion of species shared with temperate regions of Europe and North America is also supported by other studies (e.g., Servant-Vildary 1986;  Alvial et al 2008).

Figure 2. Lake Chiriacu, Ecuadorean Andes. Photo by X. Benito.

Figure 3. Lake Mandicocha, Ecuadorean Amazonia. Photo by X. Benito.

Recently, some authors have challenged the view that Andean diatoms are cosmopolitan, arguing that a higher number of endemisms should exist than those currently known (Maidana et al. 2009; Morales et al. 2012). Rumrich et al. 2000 identified 888 diatom taxa from 350 samples randomly distributed from Venezuela to Argentina along the Andes, while Morales et al (2012) found 228 taxa in a single sample from an Andean Bolivian stream (with many taxa not identified at species level). A recent study by Benito et al. (2018), analyzing a diatom metadatabase from the tropical Andes and adjacent lowlands, found a total of 1,086 taxa in 163 aquatic samples, including streams and lakes. The number of new taxa described from the tropical Andes has increased, likely due to recent advances in taxonomy (e.g. molecular markers, scanning electron microscopy), and misidentifications of original diatom type material have been reviewed (Morales et al. 2014). However, a great part of the South American diatom flora may well be yet to be discovered.

An example of endemic diatom species from tropical Andean lakes is Cyclostephanos andinus (E.Theriot, H.G.Carney & P.J.Richerson) P.M.Tapia, E.C.Theriot, S.C.Fritz, F.Cruces & P.Rivera (Figure 3). C. andinus is abundant in phytoplankton communities of Lake Titicaca (Bolivia/Perú) and is also found in other high-elevation deep freshwater lakes of the central Andes. Due its sensitive and direct response to high water lake levels (>35 m) and dilute freshwaters, this bioindicator species has fueled research in paleoclimatology (Fritz et al. 2012), biodiversity (Tapia et al. 2004), and evolutionary processes (Spanbauer et al. 2018) in South America. For instance, population size variability of C. andinus through the last 400,000 years responded to regional environmental change via punctated changes driven by global-scale climate variability (e.g. el Niño-Southern Oscillation, ENSO) that influenced lake level of Lake Titicaca. The past climate of Andean Altiplano was also reconstructed using sedimentary record of C. andinus, indicating that wet conditions in Tropical South America, as reconstructed by overflowing conditions in Lake Titicaca due to periods of increased precipitation, coincided with cold periods in high-latitude regions (Baker et al. 2001).

Figure 4. Light microscopy photos of Cyclostephanos spp. from Lake Titicaca: A-C Cyclostephanos andinus, plankton material; D-F Cyclostephanos spp., sediment core material (Fritz et al. 2012).

There is a clear potential for new studies in South America to address research questions related to diatom taxonomy, ecology, and biogeography. Future works will benefit from harmonised taxonomic data sets spanning geographically distinct regions to understand diatom diversity patterns and drivers in mountain and lowland settings. Every new study dealing with geographic distributions of microorganisms in general, and diatoms in particular, relate to concepts of endemism and cosmopolitanism. Only when geographic distribution of species can be reliably determined, ecological value and thus prioritization of regions that contribute disproportionately to maintain regional diversity are possible (e.g. Williams, 2011). Microorganisms are often neglected in conservation studies, despite their value for ecosystem functioning and structure; diatoms can be more widely and better used to support conservation planning. For the case of the Andes, the endemics diatom taxa inhabiting hipersaline lakes in the Bolivian Altiplano (‘salares’; Blanco et al., 2013) could serve as example of microorganisms indicators of reservoir environments to be preserved from increased human activities in the region (e.g. tourism).

 

References:

Alvial, I.E., Cruces, F.J., Araneda, A.E., Grosjean, M. & Urrutia, R.E. (2008) Estructura comunitaria de diatomeas presentes en los sedimentos superficiales de ocho lagos andinos de Chile central. Revista Chilena de Historia Natural, 81, 83–94.

Baker, P.A., Dunbar, R.B., Cross, S.L., Seltzer, G.O., Grove, M.J., Rowe, H.D., Fritz, S.C., Tapia, P.M. & Broda, J.P. (2001) The History of South American Tropical Precipitation for the Past 25,000 Years. Science, 291, 640 – 643.

Benito, X., Fritz, S.C., Steinitz-Kannan, M., Tapia, P., Kelly, M.A. & Lowell, T.V. (2018) Geo-climatic factors drive diatom community distribution in tropical South American freshwaters. Journal of Ecology. in press. DOI.10.1111/1365-2745.12934

Blanco, S., Álvarez-Blanco, I., Cejudo-Figueiras, C., De Godos, I., Bécares, E., Muñoz, R., Soto, R. (2013). New diatom taxa from high-altitude Andean saline lakes. Diatom Research, 28(1), 13–27

Frenguelli, J. (1939) Diatomeas del lago Titicaca. Notas del Museo de la Plata, 4, 175–198.

Frenguelli, J. (1942) Diatomeas Del Neuquén (Patagonia). Instituto del Museo de la Universidad de La Plata.

Fritz, S.C., Baker, P.A., Tapia, P., Spanbauer, T. & Westover, K. (2012) Evolution of the Lake Titicaca basin and its diatom flora over the last ∼370,000 years. Palaeogeography, Palaeoclimatology, Palaeoecology, 317318, 93–103.

Hustedt, F. (1927) Fossile Bacillariaceen aus dem Loa-Becken in der Atacama-Wüste, Chile. Arch. Hydrobiol, 18, 224–251.

Maidana, N.I., Seeligmann, C. & Morales, M. (2009) Bacillariophyceae Del Complejo Lagunar Vilama (Jujuy, Argentina). Bol. Soc. Argent. Bot., 44, 257–271.

Manguin, E. & Manguin, E. (1964) Contribution À La Connaissance Des Diatomées Des Andes Du Pérou. Edition du Muséum.

Metzeltin, D. & Lange-Bertalot, H. (2007) Tropical Diatoms of South America II (ed H Lange-Bertalot). Iconographia Diatomologica 18, A.R.G. Gantner Verlag K.G., Königstein.

Morales, E.A., Novais, M.H., Chávez, G., Hoffmann, L. & Ector, L. (2012) Diatoms (Bacillariophyceae) from the Bolivian Altiplano: Three new araphid species from the Desaguadero River draining Lake Titicaca. Fottea, 12, 41–58.

Morales, E.A., Wetzel, C.E., Rivera, S.F., Van de Vijver, B. & Ector, L. (2014) Current taxonomic studies on the diatom flora ( Bacillariophyceae ) of the Bolivian Altiplano , South America , with possible consequences for palaeoecological assessments. Journal of Micropalaentology, 33, 1–9.

Rumrich, U., Lange-Bertalot, H. & Rumrich, M. (2000) Diatoms of the Andes, from Venezuela to Patagonia/Tierra Del Fuego, and Two Additional Contributions. Iconographia diatomologica 9 ARG Gartner Verlag KG, Königstein.

Servant-Vildary, S. (1986) Les diatomées actuelles des Andes de Bolivie (Taxonomie, écologie). Cahiers de Micropaléontologie, 1, 99–124.

Spanbauer, T.L., Fritz, S.C. & Baker, P.A. (2018) Punctuated changes in the morphology of an endemic diatom from Lake Titicaca. Paleobiology.

Tapia, P.M., Theriot, E.C., Fritz, S.C., Cruces, F. & Rivera, P. (2004) Distribution and morphometry analysis of Cyclostephanos andinus comb. nov., a planktonic diatom from the central Andes. Diatom Research, 19, 311–327.

Williams, D.M. (2011) Historical biogeography, microbial endemism and the role of classification: everything is endemic. In Fontaneto, D. (ed) Biogeography of Microscopic Organisms. Is Everything Small Everywhere? Cambridge University Press, Cambridge.

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Phycological Consortium Research at Lakeside Laboratory, Iowa

The Phycological Consortium Research, an annual meeting that gather scientists interested in phycology, has been held this weekend at the Lakeside Laboratory of the Iowa State University. This meeting has the goal of creating a collaborative research among graduate and post-graduate researchers, and interchange ideas and feedbacks about their phycological research. The atmosphere of the meeting is very supportive and friendly, and the oustanding Lakeside lab facilities provide the perfect place for research and discussion in a wide range of phycological needs and objectives.

This year´s edition has been my first participation, thanks to the invitation of Dr. Sylvia Lee, one of the PCR co-founders. The Nebraska crew was represented by Melina Feitl and Sabrina Brown, my lab colleagues and friends. Besides bringing our diatom samples for identification and documentation purposes, the Saturday’s session was very productive in terms of breakout group discussions:

  • Biovolume methods
  • Taxonomic identifications: Nitzschia, Aulacoseira, Araphids, picoplankton v. bacteria (distinguishing characteristics)
  • Online resources–outside of US specifically
  • Taxonomic faux pas in manuscripts
  • Experimental methods/design for nutrient enrichment
  • Culturing cyanobacteria

As you can see, the addressed topics have been very diverse. In addition, different people gave short talk presentations about their current research: from the effects of global change to cyanobacteria blooms to the problems of biogeochemical silica cycle in lakes. A very interesting demonstration of algal pigment activity on live using a fluorometer was also given. But not all were indoor activities. We have had the opportunity to sample algae living “under the ice” of the Okoboji lake. The pictures below intend to capture some of these moments.

Hoping to see all people I met the next year at the Iowa Lakeside lab!

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Short but intense visit at University of Bern for paleolimnology study

Hi all!

Our last fieldwork in Ecuador was very successful in multiple levels. Besides the 16 total lakes sampled, two lakes from Cajas NP, in Cuenca, were in our priority list but not monitored during that trip. These two lakes are  Llaviucu (also known as Surocucho) and Fondococha. Laguna Llaviucu is an iconic lake, since some authors reported it as a pristine ecosystem, and results in studies that correlate limnological changes with climate change impacts solely. However, local sources and Ecuadorean scientists explained us that for more than 30 years, a trout farm was established there. In order to provide an alternative hypothesis, we are collaborating with the Paleolimnology group of the University of Bern. The Swiss group recovered a 1.2m core from Llaviucu to reconstruct its paleoclimatic history, and test hyphotesis about El Niño-Southern Oscillation variability. Our collaboration seeks to use diatoms as biological proxy of limnological change through time.

Core of Lake Llaviucu

I must to say that the Paleolimnology group in UniBern offered all the facilities to sub-sample material for diatom analysis. Specially, I would like to thank Tobias Schneider, who kindly welcomed me during the 2-days stay at the lab. Also Martin Grosjean, for letting us sample the mud.  Not all was work at Bern, and we also enjoyed the beautiful downtown of the city, with its calm and clean streets plenty of bars and bikes (unlocked) parked outside! Definitely, a worth place to visit and stay! Below, I share with you some pics of Bern.

 

The zytglogge tower

Aare River

 

 

 

 

 

 

 

 

 

 

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Austral winter sampling in lakes of Ecuador

After a quite long period without new postings, I´m back with a synthesis of our recent fieldwork trip to Ecuador. Together with my lab colleague Melina, and Sara, we crossed most of the Andean country from north to south, and from high to low elevation lakes in 25 days full of water and mud! Along the trip, we have had the opportunity to join with amazing Ecuadorean collaborators, including researchers from University of Cuenca and ETAPA (Henni Hampel and Pablo Mosquera), IKIAM University (Jorge Celi) and ESPOCH (Luis Quevedo). As similar I did the last February, the objective of this trip was to sample modern diatoms and lake sediments for (paleo)limnological studies, funded by a National Geographic grant lead by Prof Sheri Fritz, who also did fieldwork the first week with us, together with our close collaborator Paul Baker. In addition, our Ecuadorean super active collaborator Miriam Steinitz-Kannan joined us for the stretch sampling in Cuenca.

We spent the first week (2-8 July) in Imbabura province sampling Yahuarcocha and Piñan lakes.

Yahuarcocha lake (coring crew: Paul A Baker, Sheri Fritz, Melina Feitl and Xavier Benito)

Yahuarcocha is a well-known lake, located at the Internandean valley. Local people commonly named ‘laguna de sangre’ because its waters became red in historical times. Euglena sanguinea, caused this shift in the lake waters, associated with a combination of limnological factors such as anoxia and low water levels that thrive blooms of this eukaryotic microorganism. The sediments we recovered (4m of mud) showed reddish bands that might indicate episodes in which such limnological conditions occurred as result of climatic variability.

Piñan community, 3400 meters

 

Piñan lake

We dedicated the last days in Imbabura province to travel until Piñan community (4-hours drive), where we sampled a glacial lake located at 3400 meters above sea level surrounded by Páramo vegetation. There, we recovered a very nice 70-cm core that will be used as analogue for the Paramo lakes situated further south in Ecuador, at the Cajas National Park, Cuenca.

The sampling in Cajas (9-15 July) was really amazing, cold and exhausting though. We would like to thank specially the help received by Pablo Mosquera, a technician biologist from ETAPA, the public water company of Cuenca, who not only arranged all the logistics for the trip there (permits, car, accommodation), but also guided us throughout the National Park to reach the most wonderful selection of its lakes, and he taught the landscape history of the park that is not as pristine as thought: damming, trout farms, eutrophication, land uses changes (fires), etc. A total of 9 lakes were sampled (in chronological order): Estrellascocha, Jigeno, Torreadora, Marmolcocha, Patoquinoas, Piñancocha, Riñoncocha (kidney shaped lake), Fondococha and Dos Chorreras. Also, it is must to mention the special help received by Don Simon and his two friendly horses for carrying the scientific gear.

Don Simon and the horses, in Jigeno lake

Piñancocha lake, the highest elevation lake of Cajas NP

Fondococha lake

After the highlands, we headed up to the lowlands, in the Napo province of Ecuador (15-19 July). The objective were to sample 4 lakes floodplain lakes: Gardazacocha, Mandicocha, Añangucocha and Limoncocha. We had the unmeasurable help of local people to reach the lakes with canoes. All of the lakes suffered human impacts since the 80’s with the construction of touristic lodges surrounding them. Nowadays, touristic cabins with all of kind of activities and accommodations are the most typical picture of the Napo lakes. We intend to reconstruct these impacts by analyzing the sediments and compare pre-human impact with modern data (we have some evidences already that blue-green algae have developed in Limoncocha, and they were not present in the past!).

Napo river

Garzacocha, view from the cabin

Coring run in Mandicocha

Melina and I trying to decipher how Añangococha sediment looks like

Our last stop was in Riobamba (19-24 July), in Chimborazo province, at the center of country. Riobamba was the region where Ecuador was built as a country, having its first parliament. With 14 lakes sampled in our backs, here we wanted to core Laguna Colta, a shallow lake with two very different basins in terms of human activities; we sampled the two of them after being told that one is dredged periodically, and the other is apparently less impacted – so good basis for comparison. The second day we headed up to the Sangay NP to sample and core Atillo lakes. We wanted to do a couple of them, including Laguna Negra. After seeing its rocky steep slopes, this lake promised good adventures! We found a very deep lake (more than 40m of water column throughout), which unfortunately we couldn’t took a sediment core rather than good modern samples (there were no previous diatoms studies in Atillo lakes). Instead, we recovered a very nice core from Kuyuk lake, a nearby lake that forms an interesting lacustrine complex of several lakes connected among them: Laguna Magdalena and Laguna Atillo.

 

Laguna Negra (and Lory, our field assistant pet)

Laguna Kuyuk (and yes, Lory again taking care of us from the shore)

Overall, 16 lakes, more than 1,000 1-cm mud slices, 32 modern diatom samples (periphyton and phytoplankton), and associated water physicochemistry data that cover most of the Ecuador ecosystems: Andes, Interandean valley and Amazonia. Lot of hours are waiting us into the lab and microscope! After that, the real fun starts!

Xavier

 

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New blog on the block: Young Diatomists of the ISDR

The Young Scientists of the International Society of Diatom Research are launching the brand new YoungISDR blog. A new interface for diatomists to connect, have contact, share diatom publications (own or particularly relevant), courses, workshops and job positions worldwide!

To keep the blog up-to-date and alive in future, we need YOUR help (not only from the young scientists ;))! If you spot a conference, a workshop, an open job position, a nice new publication or have experienced a research stay/field trip/expedition related to the field of diatoms, please contact YoungISDR!

And don’t forget to sign up to our googlegroups! Big announcements will be given through this medium. We encourage also to visit the oficial Facebook page of the ISDR to keep updated with the latest news of the organization!

On behalf of the The Young Scientists team of ISDR.

Xavier

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PAGES2017 meetings: Morillo de Tou and Saragossa

Hi!

In our way waiting for the connection flight (Charlotte, North Carolina) to Barcelona, my thoughts need to be written as summary for this travel´s objective: to assist at the next PAGES meeting in Aragon Region (Spain). First, I couldn’t be more grateful to the local organizing committee that wrap up a nicely 7 days conference, broken in two different meetings: the Young Science Meeting (YSM) to be held in the small Pre-Pirinean Morillo de Tou, and Open Science Meeting (OSM), to be held in the city of Saragossa. Personally, I will have the opportunity to make an oral presentation to present our biogeography diatom project of tropical South America, in the context to advance the understanding of how these microalgae are distributed and which are the factors that drive their community assembly mechanisms and diversity, and how these relate with the topography and geologic diversity of the tropical Andes and Amazon. I have received a grant to assist and share our ongoing science from the PAGES organization, so thanks so much for this opportunity! Besides the scientific contributions, the meeting is full of social activities and discussions related with the future role of the young researchers in paleo-sciences.

Once in Saragossa, at the OSM we´ll present our results on the natural and anthropogenic evolution of the Ebro Delta in a poster format. This contribution is part of my thesis work. I am so excited to share these results with an outstanding audience of geologists, climatologists, meteorologists, biologists and chemists. Hoping to meet with friends, colleagues, and of course, with new ones to build up networks.

You can follow all PAGES meeting updates by tracking its Twitter account, which has been very active the last weeks. I´ll do it for sure 🙂 #PAGES2017

Xavier

 

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