Showing posts with label FCE. Show all posts
Showing posts with label FCE. Show all posts

Monday, February 22, 2016

Diatom of the month - February 2016: Cyclotella meneghiniana

February 22, 2016 0
by Luca Marazzi*

‘Who’ is it and where does it live?
This centric diatom’s cells are drum-shaped, the valve diameter and the density of marginal striae are highly variable. Cyclotella meneghiniana is a rather cosmopolitan species; in tropical freshwaters, it is associated with various water depths and salinity1, and, in temperate regions, it is a typical planktonic taxon in the late summer-autumn2. In North America, this species can cope with a wide range of conditions, for example from freshwater to saline waters in the Great Plains lakes3.
a)

                                                                       b)

Cyclotella meneghiniana, with a) chloroplasts and b) silica frustule after ‘chemical digestion’. Source: http://fcelter.fiu.edu/data/database/diatom/index.htm

Why are we studying it?
Studying the distribution of this and other diatoms in thousands-of-years old sediment and ice cores, paleoecologists - nature’s ‘archaeologists’ - can infer past salinity, pollution, eutrophication and climatic changes4. Moreover, analyzing water, soil and vegetation samples, contemporary ecologists can identify the reasons behind recent natural and/or anthropogenic environmental changes. In the Everglades, diatoms have been used as indicators of water pollution and management; in Northeast Shark Slough, assemblages include this month’s ‘protagonist’ Cyclotella meneghiniana alongside the benthic species Brachysira neoexilis, Encyonema evergladianum, Mastogloia lacustris and Nitzschia palea var. debilis5. A total of 127 diatom species from North and South of the Tamiami Trailwere observed in 40 samples in transitional areas; where phosphorus concentrations are higher, competition for this usually limiting nutrient is less intense and thus more species can survive and reproduce than just those tolerating its scarcity.

        

West Shark River Slough and North East Shark River Slough. Source: Johnson (2005) - http://www.nap.edu/read/11754/chapter/4#43
The Tamiami Trail (L29 road and canal) is an obstacle to the natural flow of water into the Everglades National Park that is critically important for algae and all wildlife. But water needs to flow better and faster also for the human population of South Florida and their reliable drinking water source, which is right under the Everglades! Installing water spreaders under the Trail can help restore the diffuse ‘sheet-flow’ and maintain at least portions of this wetland’s unique original landscape of sloughs, ridges and tree islands (plus alligator holes and so on…)6.

Diatom art
Human passion for nature drives scientists, artists and laypeople to investigate, but also depict and take photographs of, organisms such as birds and butterflies in the countryside or in forests, large mammals during safaris and so on. Some people ‘go deeper’ and transform the ‘invisible’ into artwork, very small overlooked life forms such as diatoms and other algae (like desmids), fungi and bacteria.

The ones below may look like some kind of flowers, but they are cells of our Cyclotella meneghiniana in a 12-color composition presented by my former colleague Gizem Berdici at the UCL “Research Images as Art” competition.                      
                            

Cyclotella meneghiniana from a brackish water lake of Turkey (original photo was taken by a light microscope). By Gizem Berdici (University College London Research Images As Art 2009 Gallery).


There is a lot to be learned about ecosystems and evolution by digging cores in lake or wetland sediments; finding, identifying and counting these minuscule algal remains enable scientists to know about their ecology, complexity, and artists to celebrate their importance and beauty. There is still time to visit the “In deep with diatoms” exhibitions at FIU BBC campus; if you are a student, why not take a break with friends and family to marvel at these beautiful artwork depicting these very real and astonishing organisms?!

 


 

Sylvia Bota’s watercolor of cells of Cyclotella, part of the “In deep with diatoms” exhibition by Tropical Botanic Artists at Florida International University.

 


* Postdoctoral Associate in Dr. Evelyn Gaiser's lab at Florida International University.

1. Tapia P.M., Fritz S.C., Baker P.A., et al. (2003). A late Quaternary diatom record of tropical climate
    history from Lake Titicaca (Peru and Bolivia). Palaeogeography, Palaeoclimatology, Palaeoecology,  
    194, 139–164.
2. “River diatoms: a multiaccess key” - http://craticula.ncl.ac.uk/EADiatomKey/html/taxon11.html
3. Fritz S.C., Juggins S. and Batterbee R.W. (1993). Diatom assemblages and ionic characterization of
    lakes of the northern great plains, North America - a tool for reconstructing past salinity and climate
    fluctuations. Canadian Journal of Fisheries and Aquatic Sciences, 50, 1844-1856.

4. Joseph Cheek “Reconstructing past Antarctic climate with microorganisms”. Science Poles (March 28, 2008) - Interview with Wim Vyverman.

5. Gaiser E.E., McCormick P.V., Hagerthey S.E. & Gottlieb A.D. (2011) Landscape Patterns of Periphyton      in the Florida Everglades. Critical Reviews in Environmental Science and Technology, 41(S1), 92–120.

6. Bramburger A., Munyon J., Gaiser E.E. (2013) Water quality and wet season diatom assemblage characteristics from the Tamiami Trail pilot swales sites. Phytotaxa, 127, 163-182.



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Wednesday, January 20, 2016

Diatom of the month - January 2016: Gomphonema parvulum

January 20, 2016 0
by Luca Marazzi*

‘Who’ is it?
The genus Gomphonema includes numerous species growing on mucilaginous stalks. These diatoms are asymmetrical biraphid, as the bottom part is usually longer and thinner than the top part and they have two raphes, narrow slits that allow them to move over surfaces. Yes, there are diatoms that perform photosynthesis, move and even eat organic matter! G. parvulum is on the lower end of the size spectrum for the genus (length from 15 to over 100 µm and width between 5 and 15 µm).

                  
                 

Gomphonema parvulum, partially
   obstructed by Eunotia, in a sample from the Florida Everglades.
        Source: Tobias and Gaiser, 2006
G. parvulum and stalks in a sample from Japan; cell body: 48 µm long, 10 µm wide. 
Source: http://protist.i.hosei.ac.jp/


Where does it live?
In North America, species of Gomphonema can be found in many habitat types in lakes and streams with pH close to 7. Gomphonema parvulum is widespread and tends to live in freshwater with high nutrient concentrations. Therefore it has been widely used as an indicator of eutrophication, including in the Everglades where agricultural fertilization has historically increased phosphorus levels1 the reduction of which is part of the largest wetland restoration programme in the world. It has a cosmopolitan distribution, but different geographical regions have been shown to host different clades of G. parvulum from Mexico, the Faroe Islands, Germany and Korea: Gomphonema parvulum sensu strictu, G. saprophilum, G. lagenula, G. narodoense2. Increasing evidence is showing that this and other species of diatoms have evolved in relation to climate, geography and water quality so that truly cosmopolitan taxa may be less common than previously thought.

Why are we studying it?
In the Everglades, G. parvulum is a dominant taxa, particularly in freshwater marshes; FIU’s Franco Tobias, Evelyn Gaiser and collaborators analyzed samples from 237 sites to suggest revisions of its taxonomy and clarify confusion that often arises in such a complicated, and at times subjective, discipline. They identified 20 taxa of Gomphonema parvulum-like diatoms from the Everglades; so far no new species have been found. This might be due to the Everglades being a ‘teenager’ wetland (about 5,000 years old) and very calcareous so that only a subset of this genus preferring acidic pH are selected3. But we have a lot of data and samples that may tell us some new ecological ‘secrets’ about Everglades diatoms - so stay tuned with the Gaiser lab!

What can you do?
If you are a Floridian or a U.S.-American, get familiar with the diatoms of the Everglades, it is your wetland! If you are not from this part of the world and you ever come to Miami for its beaches, you must also go visit this fantastic ecosystem that is increasingly threatened by sea level rise. To convince yourself, please visit the Florida Coastal Everglades Long Term Ecological Research Network website and look up for wonderful pictures of our diatoms and the precious environments they live in, from the ‘sweet-water' marshes to the salty-water mangroves and more!


Shark River Slough - airboat morning. Photo by Franco Tobias (27 September 2011).


Tributary of the Shark River. Photo by Stephen Davis (26 June 2014)


* Postdoctoral Associate in Dr. Evelyn Gaiser's lab at Florida International University.

1. Gaiser E.E., Childers D.L., Jones R.D., Richards J.H., Scinto L.J., and Trexler J.C. (2006). Periphyton responses to eutrophication in the Florida Everglades: Cross-system patterns Eutrophication today 355 of structural and compositional change. Limnology and Oceanography 51: 617–630
2. Abarca N., Enke N., Zimmermann J., Jahn R. (2014) Does the cosmopolitan diatom Gomphonema parvulum (Kützing) Kützing have a biogeography? PLOS One 9: e86885. doi: 10.1371/journal.pone.0086885
3. Tobias F.C.A. and Gaiser E.E. 2006. Taxonomy and distribution of taxa in the genus Gomphonema from the Florida Everglades, U.S.A. Diatom Research 21: 379-405.
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Wednesday, December 16, 2015

Diatom of the month - December 2015: Tursiocola ziemanii

December 16, 2015 0
by Luca Marazzi*

‘Who’ is it?
Tursiocola ziemanii is one of three new species described by FIU’s Dr. Thomas Frankovich and colleagues in a recent paper in Phytotaxa, a journal dedicated to the publication of discoveries on the taxonomy of plants, algae, mosses, lichens and fungi. The name was chosen to honor Dr. Joseph C. Zieman (1943–), in recognition of his generous support of diatom research in, and contributions to our understanding of, Florida Bay.



A manatee in South Florida.
Source: http://eyeonmiami.blogspot.com/2014/05/did-i-see-manatee-dying-yesterday-by.html
Scalebars: a. 5 µm; b)10 µm; Length Range: 20-61 µm;
                         Width Range: 2.4-5.2 µm; Striae in 10 µm: 22-25
Scanning electron microscopy photos of Tursiocola ziemanii in a) valve or face view and b) girdle or lateral view.
Source: Frankovich et al. (2015)






Where does it live?
This diatom lives in a somewhat strange place: on the skin of the West Indian manatee (Trichechus manatus), a familiar ‘face’ in Florida waters! And in very high numbers: in Frankovitch’s study, 90% of all diatoms on the manatee skin were of Tursiocola ziemanii. This diatom probably tolerates large changes in salinity as manatees are migratory mammals who move from freshwater to marine environments1. There are many other epizoic diatoms - that is to say they live on animals like whales, porpoises and even on other small plankton!

Why are we studying it?
There are between 20,000 to 2 million species (!) of diatoms on Earth with many new discoveries under way. About two years ago, Frankovich and colleagues took samples of dried skin from the belly area of a deceased adult female manatee and, after these were treated chemically at the Florida Bay Interagency Science Center (Key Largo), Tursiocola ziemanii, and her diatom ‘sisters’ T. varicopulifera and T. costata were ready to be brought to light under the microscope. Will they become famous as the ‘manatee diatoms’?

What can you do?
Diatoms can tell us so much about the historical and present conditions of many environments and allow us to predict how these will change. Their diversity and ability to disperse, live and reproduce in very different places and conditions is fascinating and important. That is why many researchers have been studying these microorganisms since the times of the father of evolutionary thought, Charles Darwin, who once even wondered: “were these created that they might be examined and admired under the high powers of the microscope?”. But algae such as diatoms also inspire artists who arrange them in truly amazing compositions, draw, paint and even build sculptures of them!

 


“Diatoms-Silica” (2015) by Xavier Cortada, FIU Artist In Residence in the College of Architecture & the Arts. Pieces are made of glazed porcelain and rest on glass mosaic tiles.



    Video on Klaus Kemp’s stunning arrangement    
    art. Source: https://vimeo.com/90160649 

The least we can do is get interested and admire these ancient aquatic plants and ‘listen’ to what they tell us - via ecological research- about the environment, its natural cycles and the vast anthropogenic ongoing changes. After all, we would not breathe oxygen if it wasn’t for plants and algae!


* Postdoctoral Associate in Dr. Evelyn Gaiser's lab at Florida International University.

1. Frankovich T.A., Sullivan M.J. & Stacy N.I. (2015) “Three new species of Tursiocola (Bacillariophyta) from the skin of the West Indian manatee”. Phytotaxa 204: 33–48.
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Thursday, October 29, 2015

Diatom of the month - November 2015: Encyonema evergladianum

October 29, 2015 0
by Luca Marazzi*

‘Who’ is it?
Encyonema evergladianum is a diatom living attached to various substrates, but is also able to move, if it needs to. It was originally described in 1997 by Krammer from samples collected in the Florida Everglades, USA.

                 Scalebar = 10 µm    Scalebar = 5 µm 

Encyonema evergladianum (Length range: 16-33 µm; Width Range: 4-6 µm; Striae in 10 µm: 20-22)

Where does it live?
This beautiful diatom lives in the Everglades periphyton mats, characteristic multi-color ‘biological carpets’ inhabited by bacteria, fungi and, importantly, by algae attached to soil and plants that feed all sorts of critters. These are in turn eaten by fish that, as we know, become food for birds and for humans too.

Nine mile pond.

                   
                       Calcareous periphyton mat.    



In the interior Everglades, these mats have a top calcium carbonate (CaCO3) layer produced by cyanobacteria (Gaiser et al. 2011, Hagerthey et al. 2011). These photosynthetic organisms are a lower-quality food for invertebrates and fish than diatoms and green algae (Geddes and Trexler, 2003). Encyonema evergladianumhas been observed in rivers throughout South Florida and in Central Texas, but these records have not been confirmed. Our young scientist Viviana Mazzei found this species in karstic, freshwater wetlands up to the spectacular coastal mangroves in Everglades National Park.

Why are we studying it?
To understand how sea level rise affects the abundance of Encyonema evergladianum and the concentrations of solutes (for example, calcium, sodium, chlorine) and nutrients (nitrogen and phosphorus) in the periphyton mats, one of the things we do is to control small parts of the environment in mesocosm (‘middle-sized world’) experiments. By increasing salinity and phosphorus levels in the periphyton mats, we are generating new ecological knowledge to help conserve the Everglades, an ecosystem at high risk, as you can see in this recent TV documentary: “Everglades Under Attack”.





    
Scheme of freshwater (FW), marine water (MW) and groundwater (GW) flows and varying ratios nitrogen : phosphorus concentrations (N:P).   

Mesocosm experiment in Key Largo to assess effects of salinity and phosphorus on diatom abundance and periphyton mat mineral content.

What can you do?
Let us not forget where some of our food and a lot of the oxygen we breathe come from, invisible aquatic plants like our diatom of the month! Many fish eat snails and other little animals that feed on hundreds of species of algae like Encyonema evergladianum. Share this information with your friends, family and colleagues, follow us on Facebook and go visit the Everglades, a unique wetland that we need to study and protect as our natural heritage!


* Postdoctoral Associate in Dr. Evelyn Gaiser's lab at Florida International University. 
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