Showing posts with label Everglades. Show all posts

Thursday, June 22, 2017

Diatom of the Month – June 2017: Fragilaria synegrotesca

vivien June 22, 2017 0

by Nick Schulte*

I think Fragilaria synegrotesca is a cute diatom. Although long and lanky (nothing wrong with that!), F. synegrotesca has an adorable, sometimes very slight, potbelly (Fig. 1).

Fig. 1. a) Live frustules in a rosette colony (http://fcelter.fiu.edu/data/database/diatom/index.htm?species=3568)

b) Fragilaria synegrotesca in valve view (Schulte 2014).

Now, some boring diatomist (e.g., me) might describe that little bump in the middle right as “a unilaterally expanded, hyaline central margin” and that’s accurate enough. But I also like to think of it as F. synegrotesca’s belly pooch. It brings to my mind the potbellies of seahorses, pigs, puppies and toddlers, and it seems very boop-able.

But let’s move past the physical attributes of this diatom, as the allure of this species is in its “actions”. Fragilaria synegrotesca has so far only been reported from karstic wetlands of the Caribbean and is most well-known from the Florida Everglades. In the Everglades, F. synegrotesca is nearly ubiquitous (Fig. 2), and it’s one of the five most abundant species in the calcareous periphyton mats in the nutrient-poor freshwater marshes (Gaiser et al. 2006).

Fig. 2. Relative abundance (%) of F. synegrotesca across the Everglades (data from the Comprehensive Everglades Restoration Plan Monitoring and Assessment Plan).

A major issue in Everglades restoration is getting the amounts of water and nutrients that enter this wetland right. Every winter/spring (the “dry season”), sloughs and inundated prairies often dry down. This happens more often and more severely now than in the “natural” pre-drainage state in many sites. But water managers (e.g., the South Florida Water Management District) can’t just send water through the marshes unless it’s “clean” (e.g., low in phosphorus), so as not to harm organisms that are adapted to this wetland’s low nutrient waters. So, Everglades restoration is between a bit of a rock and a hard place: we need to deliver more water to help the organisms that need high water (and can’t handle severe dry-down – e.g., many fish), but not at the expense of the organisms that can’t handle high nutrients in the water (e.g., some grasses and sedges).

Fragilaria synegrotesca is one of those organisms that doesn’t like to be dried out (Gottlieb et al. 2005, Lee et al. 2013), and its preference for being wet makes it a potentially “reliable indicator of the absence of periodic drying” in the ‘Glades (Gaiser et al. 2011). We can therefore use the abundance of this species (alongside other indicators) to measure the effects on biodiversity that potential reduced water flow might have upon different locations. This information can then inform decisions on how much water should be sent where and when – all key questions in Everglades restoration.

Unlike its freshwater-loving, high nutrient-hating buddies Brachysira microcephala, Encyonema evergladianum, and Mastogloia calcarea (let’s call them the “Fresh Diatoms of Belle Glades,” or “Freshies” for short), F. synegrotesca can also live comfortably in moderate phosphorus (P) concentrations and slightly salty water (“oligohaline”).

So, we can think of F. synegrotesca as that close friend that is too cool for us sometimes and likes to hang out with hipper, more indulgent folks.

And if this diatom is found in relatively high abundance in the absence of the Freshies, we know that area might be getting a little too phosphorus-y and/or salty than is normal. Now, there are some regions of the Everglades where finding F. synegrotescain enriched or salty places is normal, but by now we know which places are “normally” enriched/salty and which are not. So, if we see this species hanging out with the Salty Boys or the +P Posse in the good side of town (i.e., a normally freshwater, low nutrient place), we know something’s about to go down. In this way, I guess F. synegrotesca is also like that sweet suburban kid who gets caught up in the wrong crowd, and we’d rather see it back at home with the Freshies.

But here is some science to back up these potentially confusing analogies. In the Everglades, the total phosphorus (TP) optimum of F. synegrotesca is 270±202 µg P g^-1periphtyon (Gaiser et al. 2006), and this species has been designated as an indicator of high TP (La Hée and Gaiser 2012). Compare that to oligotrophic, freshwater indicators (B. microcephala, E. evergladianum, and M. calcarea) that have a mean TP optimum of 159 µg g^-1 (Gaiser et al. 2006). Our diatom of the month also has a salinity optimum and tolerance of 5±7.3 ppt (parts per thousand) – slightly higher than the Freshies (mean optimum across those 3 taxa = 2.9 ppt) (Wachnicka et al. 2010). Importantly, though, F. synegrotesca is generally not an indicator of a nutrient or salinity impacted site. Rather, its presence might indicate that a place is in limbo: it’s not too far gone, but it’s worse than we would expect if everything was OK. And F. synegrotesca alone doesn’t tell us much: rather, we have to look at the entire community of diatoms (and other algae and cyanobacteria) in order to make sense of the ecological impacts of modified nutrient levels and hydrology. So we use an “indicator community” analysis approach rather than “indicator species.”

As an example, in the Comprehensive Everglades Restoration Plan (CERP) Monitoring and Assessment Program (MAP) scientists from the Gaiser and Trexler labs report on how ~150 sites across the Everglades (and their animals, plants, and algae in periphyton mats) are affected by nutrient enrichment. To do this, one of the best measurements of site alteration is a combined periphyton TP-diatom community composition metric (RECOVER 2014, see pages 6-33 – 6-39). They use a “stoplight” reporting technique: green means baseline (“success”) conditions (TP < 200 µg / g), yellow means “caution” (TP = 200-250 µg / g), and red means “altered” (TP > 250 µg / g) (Fig. 3). Fragilaria synegrotesca is one of the diatoms that can contribute to a “caution” designation if it’s found away from the Freshies.

Fig. 3. Condition status of sampling sites from 2011 using a periphtyon TP-diatom community metric (from RECOVER 2014; Fig. 6-17).

So, while F. synegrotesca may seem a bit pudgy, it is a mover and shaker of the diatom scene in the Everglades. In the Everglades, there is the potential for more widespread dry-downs, human-caused phosphorus enrichment in the Everglades interior (particularly in the northern Everglades and near canals), and for sea-level rise in the southern Everglades (pushing saltier, nutrient-enriched water into the freshwater inland regions). Fragilaria synegrotesca and its associated community are great tools to understand how such disturbances are affecting the nature of this wonderful and important wetland. The ongoing diligent scientific monitoring and analysis (e.g., by CERP MAP and the Florida Coastal Everglades Long Term Ecological Research program) allow us to understand things like a potbellied diatom that inform sustainable management and conservation of the entire ecosystem.

*Ph.D. student at the Institute of Arctic and Alpine Research, University of Colorado Boulder and FIU Algae Research Lab alumnus

Gaiser, E. E., Childers, D. L., Jones, R. D., Richards, J. H., Scinto, L. J., & Trexler, J. C. (2006). Periphyton responses to eutrophication in the Florida Everglades: Cross‐system patterns of structural and compositional change. Limnology and Oceanography, 51(1part2), 617-630.

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.

Gottlieb, A., Richards, J., & Gaiser, E. (2005). Effects of desiccation duration on the community structure and nutrient retention of short and long-hydroperiod Everglades periphyton mats. Aquatic Botany, 82(2), 99-112.

Lee, S. S., Gaiser, E. E., & Trexler, J. C. (2013). Diatom-based models for inferring hydrology and periphyton abundance in a subtropical karstic wetland: Implications for ecosystem-scale bioassessment. Wetlands, 33(1), 157-173.

RECOVER (2014). System Status Report. Comprehensive Everglades Restoration Plan, Restoration Coordination and Verification (RECOVER). U.S. Army Corps of Engineers Jacksonville District, Jacksonville, Florida, and South Florida Water Management District, West Palm Beach, Florida, USA. http://141.232.10.32/pm/ssr_2014/cerp_ssr_2014.aspx

Schulte, N. (2014). Fragilaria synegrotesca. In Diatoms of the United States. Retrieved June 16, 2017, from http://westerndiatoms.colorado.edu/taxa/species/fragilaria_synegrotesca

Wachnicka, A., Gaiser, E., Collins, L., Frankovich, T., & Boyer, J. (2010). Distribution of diatoms and development of diatom-based models for inferring salinity and nutrient concentrations in Florida Bay and adjacent coastal wetlands of south Florida (USA). Estuaries and Coasts, 33(5), 1080-1098.

Tags # Algae # Diatoms # Everglades Continue Reading

Thursday, February 23, 2017

Diatom of the Month: February 2017

vivien February 23, 2017 0

The Art of Diatoms
by Xavier Cortada
Artist-in-Residence

FIU School of Environment, Art and Society

Fig. 1. Cortada’s one-hundred diatom works on tile (each 6″ x 6″), 2017.

I marvel at looking into a microscope.

I focus in and see time. I see the past, really far into the past. I see beautiful small aquatic plants encased in glass that lived on our planet for many millions of years. Sitting inside Dr. Evelyn Gaiser’s Algae Research lab at Florida International University in Miami, I look at a slide and see diatoms.

Diatoms transport me to a place so distant in time that it wouldn’t look like the Earth I know. They help connect me to an Earth I am trying to better understand. An Earth fluid. An Earth as process. An Earth completely interconnected. An Earth generating life forms across space and time.

Fig. 2. Xavier Cortada, Drawings of Diatoms from the Everglades, 6″ x 6″, ceramic tile, 2017.

In diatoms I also see moments captured in time. Scientists can determine the past salinity of water by examining the glass shells of diatoms preserved in sedimentary core samples. Each diatom species has a different salinity preference, so changes in the mixture of fresh and sea water (driven by sea level rise and water management) can be inferred from past diatom remains.

Their presence in the layered sediment connects us to the ecosystem in which they thrived while they were alive. Indeed, they are a portal to what once was so that we can better learn how to protect what now is.

A diatom glass shell is a talisman.

The tiniest of talismans-- as tiny as a cell: a single-celled organism that lives in the water and harnesses the power of the sun to convert CO₂ into organic substances to sustain its life and releasing oxygen in the process. Indeed, the oxygen in one of every third breath we take was returned to the atmosphere by and through diatoms!

Elegant, gem-like, the bilaterally symmetrical shapes of many diatoms move me to depict them in my art. I do so to celebrate the science that shows us their relevance in our world. These are some of the works:

Fig. 3. Xavier Cortada, “Diatom Fountain” 16’ x 8’ x 8’, ceramic tile, 2017.

Diatom Fountain (Fig. 3)

I am currently putting finishing touches on Diatom Fountain. Comprised of 1,616 handmade, hand-painted ceramic tiles, we just need to add water as soon as we get the lights and water pump installed on this sixteen-foot tall public fountain. It is my latest public work, one of several featuring diatoms.

This one is at Miami-Dade Housing Authority’s Smathers Plaza, an elderly living community in Little Havana. Here, four vertical water channels disrupt the natural flow of diatoms across the sculpture, much like dredging and canals have disrupted the flow of the River of Grass across South Florida. I like depicting diatoms in public places as a way of engaging audiences – an entry point for them to learn about how scientists use diatoms to monitor water flow and quality in the Florida Everglades and throughout Florida’s ecosystems.

Florida Coastal Everglades LTER (Fig. 4)

Using a microscope, I captured the image of a diatom from samples used by scientists working in the FIU-led Florida Coastal Everglades LTER (Long Term Ecological Research) program to study the ecology of the Everglades and sea level rise. In the digital art piece, my first work about diatoms, I had this diatom image hover over a layer of maps (that I captured using Google maps) showing the artificial canals and lakes created to develop parcels of developable land where the River of Grass once flowed.

Miami Beach City Hall (Fig. 5)
To create the Centennial art piece for the City of Miami Beach, I used a diatom as the central image for the digital work. The diatom depicted in the art piece was living on Biscayne Bay in 1915. It was creating the very air Miami Beach founders breathed 100 years ago as they brought the city to life. Its glass shell, all that remains from the diatom, is used by scientists today to see what was as they research environmental issues crucial to the city in the century to come.

Fig. 6. Xavier Cortada, “Florida is… Sunshine (Sunset)” digital art, 2015.

Florida Turnpike (Figs. 6, 7)
I was commissioned to create permanent public art installations in three Florida Turnpike plazas, making them cultural destinations in and of themselves. Wanting to connect tourists and locals to Florida’s true beauty--nature, I portrayed Florida’s life-giving sun, its endangered animals and native wildflowers. At the Florida Turnpike Turkey Lake Plaza near Orlando, I depicted the Florida’s sun-using and water-bound diatoms that harness its power thus creating oxygen. Conceptually, I wanted to track a day in the life across the Sunshine State:

• Sunrise: Huge diatom-clad sunrays rise above the Northbound entrance (on the east side

of the Turkey Lake plaza),

• High Noon: life-giving diatoms appear as circles on the ceiling at the center of the building

at high noon, and

• Sunset: the rays set above the Southbound entrance on the west.”

Tags # Art # Diatoms # Everglades Continue Reading

Thursday, February 16, 2017

Researching Algae, the Unsung Heroes of Aquatic Food Webs

vivien February 16, 2017 0

by Luca Marazzi^*

Why is it important to study algae?To start with, algae produce ~ 50% of the oxygen on planet Earth, they are food for small and large animals that in turn are eaten by people, but they also recycle nutrients and absorb CO₂ from the air; by existing and doing their own thing, these microorganisms provide these so called ecosystem services to human beings (Fig. 1). Moreover, as algae reproduce fast and are often adapted to specific environmental conditions, understanding how many species of algae, and which ones, live where and why give us cues as to the health of aquatic ecosystems, such as rivers, lakes, and wetlands.

Fig. 1. Simplified scheme of the role of algae in food webs (from my Ph.D. Thesis).

* Dr. Luca Marazzi is a freshwater ecologist working in Dr. Evelyn Gaiser’s research group in the School of Environment, Arts and Society at Florida International University. His main interest is how biodiversity, ecology, and distribution of algae in subtropical wetlands change with hydrology, nutrient concentrations and habitat. He curates the “Diatom of the month” blog series aimed to raise awareness on these algae, key primary producers and indicators of environmental change.

How did I get to do research on algae? For my Environmental Science MSc dissertation project, I worked in the northern Italy’s Alps studying Passerine bird migration, then my career path took me to office-based research on air quality and climate change. Wanting to go back to field research, I got a Ph.D. opportunity at University College London to study the biodiversity and biomass of microscopic algae in the Okavango Delta, a subject and a place I didn’t know much about, apart from biology courses and natural science readings. Between 2009 and 2010, I spent ~3 months in Maun (NW Botswana), to carry out the necessary sampling in this incredible, remote, and near pristine wetland in the middle of the Kalahari; another ~ 70 months were needed to master and apply taxonomy and microscope skills, conduct statistical analyses, read, think, and write my Thesis, as well as working to support my graduate studies.

Fast-forward 8+ years, here I am in sunny Miami, some 8,000 km away from the cold and misty mountain pass where I did my MSc research and 12,200 km from the Okavango, to work on another amazing wetland, the Everglades, as part of a Postdoctoral Associate contract in Dr. Evelyn’s Gaiser laboratory at Florida International University (FIU). After a few months at FIU putting together a database for the Comprehensive Everglades Research Plan Monitoring and Assessment Plan (CERP-MAP) and planning my publications, I decided, with my postdoc and Ph.D. advisors, to undertake an ambitious comparative study of patterns and drivers of species richness and life-history strategies in the Okavango and Everglades. We estimated that, the Okavango hosts, on average, ~80 species of algae in each sampling site, the Everglades have ‘only’ ~ 20 (Fig. 2). This is likely due to phosphorus scarcity, habitat fragmentation due to water diversion schemes, and nutrient pollution in the Everglades whereas the Okavango is still a near pristine wetland. Moreover, Florida is a long peninsula, while the Zambezi ecoregion in Africa has been historically well connected so that organisms may be able to better disperse to and from this wetland than in the Everglades. For more information, our paper “Algal richness and life-history strategies are influenced by hydrology and phosphorus in two major subtropical wetlands” is published in this month's issue of Freshwater Biology.

Fig. 2. Map of estimated algal richness and photos from the air: Okavango (above) and Everglades (below). Okavango (site averages); UPH= Upper Panhandle; LPH=Lower Panhandle; XAK=Xakanaxa; BOR=Boro; SAN=Santantadibe.Everglades; LKO=Lake Okeechobee; LOX=Loxahatchee; Out_ENP=Outside of Everglades National Park (including the Water Conservation Areas, WCA 2 and 3); ENP=Everglades National Park.

Although, in the Okavango, the flooding cycles have a stronger influence on species richness, as compared to phosphorus in the Everglades, maintaining and restoring the natural hydrology in these wetlands is critical for the preservation of algal communities, and thus for the health of food webs. Due to their outstanding geographic features and biodiversity, both these wetlands are protected as World Heritage sites, and are included in the Ramsar Convention on Wetlands of International Importance, and so it is critical to keep monitoring these ecosystems.

What’s next?

I am currently researching how algal dominance changes with nutrients and hydrology in the Everglades, which is relevant for freshwater flow and water quality restoration scenarios. I am also trying to create opportunities for comparative research in other subtropical wetlands. Last September, I visited the Nanjing Institute of Geography and Limnology of the Chinese Academy of Sciences and, with other 800 experts, attended the excellent 10^th INTECOL Wetlands conference in Changshu. I presented my comparative work and co-organized a workshop on future directions in wetlands studies, strengthened previous connections and made new ones with various colleagues working in Asia, South America and Australia. In June, other FIU scholars and I are planning to present our work at the next Society of Wetland Scientists’ meeting in Puerto Rico (“Celebrating Wetland Diversity Across the Landscape: Mountains to Mangroves”), where we aim to foster new collaborations with ecologists conducting research on wetland ecosystems and food webs in Central and South America, and beyond. Moreover, Dr. Gaiser, Dr. Barry H. Rosen (USGS) and I co-organized a special session on how algae / periphyton mats may respond to different nutrient and hydrology scenarios in the Everglades for the Greater Everglades Ecosystem Restoration (GEER 2017) conference. As wetlands are facing unprecedented anthropogenic impacts due to, for example, land use change, water diversion, and global warming, such collaborations among scientists, and between us and policy makers, are crucial to foster and inform sustainable management practices and strong conservation and restoration activities.

Fig. 3. (from top to bottom) In front of the conference venue with Drs. Wolfgang Junk (Federal University of Mato Grosso, Brazil), Max Finlayson (Charles Sturt University, Australia) and Xuhui Dong (Aarhus Institute of Advanced Studies, Denmark and Chinese Academy of Sciences); our International Network for Next Generation Ecologists workshop; two pictures from one of the conference fieldtrips to Shanghu Lake.

Tags # Algae # Conferences # Ecology Continue Reading

Friday, May 20, 2016

Diatom of the month – May 2016: Rhopalodia gibba

vivien May 20, 2016 0

by Luca Marazzi*

Rhopalodia gibba belongs to the epithemioid group, that is to say it has valves symmetric about a line (bilateral symmetry), but asymmetrical to the apical (longitudinal) axis, the raphe system is well developed, enclosed within a canal, and positioned near the valve margin¹. It is longer and more slender than other species such as the lunate R. gibberula, and the more arched R. musculus; it is found in the benthos, attached to substrata such as plant (epiphytic), or gliding more freely and opportunistically². Interestingly, R. gibba seems to have declined significantly in the United Kingdom due to agricultural intensification and associated large use of nitrogen fertilizers. In fact, this pennate (bilaterally symmetric) diatom species lives in nitrogen poor habitats, but it has evolved an endosymbiosis with cyanobacteria that fix nitrogen³. So it does not like when there is too much nitrogen around, and loses its competitive edge against other fellow diatoms and algae, but it’s quite happy with abundant phosphorus…

Rhopalodia gibba in valve and girdle view (scalebars = 10 µm; from Hebron Swamp, Cheboygan Co, MI; photos by P. Kociolek www.westerndiatoms.colorado.edu); (top right) a specimen of the lunate R. gibberula (www.fcelter.fiu.edu); R. gibba with cyanelles (inset above), its endosymbiotic cyanobacteria: https://microscopesandmonsters.wordpress.com; cell length ~ 100 µm & max width ~ 20 µm).

…such as in some areas of the Everglades, where R. gibba can tolerate high phosphorus (P) concentrations (> 800 μg P g⁻¹) in the periphyton mats⁴. This species has been found to dominate primary production in restored prairie wetlands in South Dakota that had persistent high P levels.⁵Moreover, it is well adapted to high conductivity and alkalinity, such as in boreal wetlands in Wood Buffalo National Park(in Northeast Alberta, Canada); here R. gibba lives in yellow diatom ponds (!), nesting sites of whooping cranes⁶. The diatom ponds are shallow spring-fed, alkaline wetlands with bicarbonate, sulphate, calcium and magnesium. In these open habitats, cranes can see predators well, and they find their favored nesting material, bulrush⁶. So preserving the habitats of these glass-celled algae that fix nitrogen thanks to cyanobacteria living in their cells, we end up conserving large charismatic species too (and viceversa), from the bottom to the top of the food chain.

Ponded wetland in Wood Buffalo National Park (source: www.emaze.com).

A whooping crane (source: http://cranetrust.org); this large bird uses diatom ponds as nesting habitats.

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

1. Source: https://westerndiatoms.colorado.edu/taxa/morphology/epithemioid

2. M. Kelly “More about Croft Kettle” - https://microscopesandmonsters.wordpress.com/tag/rhopalodia-gibba/

3. Round, F. E., R. M. Crawford, and D. G. Mann. 1990. The Diatoms: Biology and Morphology on the Genera. Cambridge University Press, Cambridge, U.K.

4. 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.

5. Mayer P.M. & Galatowitsch S.M. (2001) Assessing ecosystem integrity of restored prairie wetlands from species production–diversity relationships Hydrobiologia, 443, 177–185.

6. Tilmoney K., Zoltai S.C. & Goldsborough L.G. (1997) Boreal diatom ponds: a rare wetland associated with
nesting whooping cranes. Wetlands, 17, 539–51.

Tags # Algae # Diatoms # Education and Outreach Continue Reading

Wednesday, April 20, 2016

Diatom of the month – April 2016: Cocconeis placentula

vivien April 20, 2016 0

by Luca Marazzi*

‘Who’ is it and where does it live?

This diatom is monoraphid, that is to say it has a raphe only on one valve, as shown in the figures. Monoraphid species are one of 9 major morphological types of diatoms - the other ones are: centric (like Cyclotella meneghiniana), araphid (e.g. Asterionella formosa, which forms star-shaped colonies!), eunotioid (e.g. the beautifully ornamented Eunotia diadema), symmetrical biraphid (e.g. the slender Navicula lanceolata), asymmetrical biraphid (e.g. Gomphonema parvulum), epithemioid (e.g. Rhopalodia gibba, which hosts nitrogen-fixing bacteria as symbionts), nitzschioid (e.g. the organic pollution-loving Nitzschia palea), and surirelloid (the big Surirella ovalis)¹. Like in many other cases, the taxonomy is far from settled though; following recent research, numerous specimens usually named C. placentula should be more accurately named Cocconeis lineata and C. euglypta².

Cocconeis placentula / C. lineata from a 2003 Everglades sample (Dr. Evelyn Gaiser Lab photo archive).

Valve with (left) and without (right) raphe (http://westerndiatoms.colorado.edu/; scalebar: 10 µm). Recent taxonomic work suggests that this be named C. euglypta (pers. comm. Tom Frankovich)².

Like many other diatoms that are adapted to specific environmental conditions, Cocconeis placentula, is a freshwater epiphytic species that tolerates high salinity levels in the water. Why? A 2013 study on the Coroong wetlands (Australia) suggests that this diatom (and C. pinnata) is capable of regulating the size of its pore holes which control nutrient flows between the cells and the environment³. With higher concentrations of salt, this diatom basically spits out the ions in excess from aptly enlarged pores.

Why are we studying it?

Algae such as our diatoms of the month are extremely useful indicators or sentinels of the environmental changes occurring in freshwater ecosystems, including (as by now you know, if you read previous posts) the Florida Everglades. A recent study on sediment cores collected in this wetland’s marshes identified several species best adapted to shallow habitats with short hydroperiod (the number of days during which a site is flooded / wet), e.g. Nitzschia serpentiraphe, Achnanthidium minutissimum, and C. placentula, that were most abundant in shallow water / short hydroperiod habitats (<38 cm; <300 days), as opposed to deeper water / long hydroperiod habitats (>46 cm; >400 days), which were preferred by other taxa such as Eunotia flexuosa and Encyonema evergladianum⁴. So data on these microalgae, together with key hydrological and water quality information, can improve our understanding of the effects of water flow changes in the Everglades. The impacts of large-scale canalizations and water retention schemes - to respectively irrigate crops and protect cities from either floods or droughts – on the ecosystem – and that of restoration projects to enhance water flow to natural areas have been monitored for many years. Measuring and estimating past and present environmental conditions is crucial to provide South Florida water managers and state and federal agency policy makers with realistic scenarios of what the marshes and prairies will look like in the years to come, subject to different natural conditions and human choices. These models are then used by organizations such as the South Florida Water Management District, and the US Army Corps of Engineers, for example to increase the important flows of freshwater to Everglades National Park (“The largest subtropical wilderness in the United States”).

Faculty and staff members of FIU, South Florida Water Management District, and US Army Corps of Engineers near a large tree island during an official visit to Water Conservation Area 3A (November 2015).

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

1. Source: http://westerndiatoms.colorado.edu/taxa

2. Romero O.E., Jahn R. (2013) Typification of Cocconeis lineata and Cocconeis euglypta. Diatom Research,

28, 175–184.

3. Leterme S.C., Prime E., Mitchell J., Brown M.H., Ellis A.V. Diatom adaptability to environmental change: a case study of two Cocconeis species from high-salinity areas. Diatom Research, 28, 29–35.

4. Sanchez C., Gaiser E.E., Saunders C.J., Wachnicka A.H., Oehm N., Craft C. (2013) Challenges in using siliceous subfossils as a tool for inferring past water level and hydroperiod in Everglades marshes. Journal of Paleolimnology, 49, 45–66.

Tags # Algae # Diatoms # Ecology Continue Reading