simpple025: Periphyton

Showing posts with label Periphyton. Show all posts

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

Wednesday, January 14, 2015

Algae Met a Bear: Algae where you'd least expect them!

vivien January 14, 2015 0

Polar bear! In the EVERGLADES?!?!

So how many of you know the poem "Algy"?

"Algy met a bear.
The bear met Algy.
The bear was bulgy.
The bulge was Algy."

I think my dad sang "Algy" to me when I was a little tyke, though in my 3-year-old wisdom I must have taken "Algy" as "Algae" and from then on aspired to become a phycologist. Now, some attribute this verse to Ogden Nash, while others chalk it up to Anonymous (that great and varied writer!). And while this verse may be humorous, it's not truly nonsense (though this sentence is). I've seen analysis of Algy and the bear as an allegory for existentialist being (what does it mean "to be"?), while others just say (spoiler alert) that the bear ate Algy. BUT, I think they're all wrong as a result of a translational error where "Algy" should be "Algae" as my 3-year-old self clearly realized. THEREFORE:

Looks a little green 'round the edges.

"Algae met a bear.
The bear met algae."

These lines are clearly discussing the cyanobacteria that grow in polar bear hair fibers! That's right - there's a type of cyanobacteria (blue-green algae) that lives in the hollow hairs of polar bears. This isn't a natural phenomenon, as the cold habitat of polar bears prevents algae from normally colonizing polar bear fur, but in warmer zoos algae find the hair follicles of the bears a cozy place to set up shop (and turn the polar bears what some think is a sickly "green around the edges").

"The bear was bulgy.
The bulge was algae."

All pictures are a different scale: 1. Polar bear hair (tiny dots are the algae), 2. Close-up of the tiny Aphanocapsa dots, 3. Super close-up of Aphanocapsa montana, aka "the bulge". From Lewin et al. 1981.

These lines are, likewise, clearly categorizing the specific type of the cyanobacteria in those hairs. Lewin et al. in 1981 found that the algae living in polar bear hair were cyanobacteria of the order Chroococcales, resembling the species Aphanocapsa montana. Individuals of this species are unicellular and spherical, described as globules and gelatinous. I think Anonymous added "bulgy" to that description!

Glad we cleared that up.

But from here we can go completely crazy. You know that greenish tinge of sloths? Algae. (This one's really quite cool, too. Sloth hairs have cracks that allow rain to saturate the follicle, which in turn allows algae to grow hydroponically - in this case a green alga named Trichophilus welckeri is most common.

There's a really quite hilarious and informative recent study by Pauli et al. 2014 and article that summarizes a very "crappy" pathway among sloths, moths, and algae - check it out and impress your friends! Make that one sloth-obsessive think twice about that love for adorable sloths. And even a new genus and species of red has been described from sloth hair!)

Cute obligatory sea otter.

I think I also promised a picture of a sea otter. You know what? Algae in their hair, too.

And if we look beyond hair, we see all sorts of epizoic algae (algae growing on animals): on shells, turtles, lizards, manatees! Moral of the story? Wash your hair. Algae are here to take over the world.

Oh? You don't see the relevance of this to graduate research in the Everglades? Well, I could attribute this to the strain of my M.S. research finally getting to me, propelling me into babbling analysis of children rhymes and my research project (I wonder if I could squeeze this into a chapter of interdisciplinary applications of the research...). But, really, I was thinking up ways of introducing those that need no introduction: ALGAE! Pop quiz for name recognition:

Agar, biofuels, harmful algal blooms, ice cream, Naked Juice, nori, oxygen, Spirulina.

This author's personal favorite. And,
yes, it does have carrageenan.
And apparently half the fat. Tasty algae.

If any of those sound familiar, you've likely come across algae in some way or another, either as a product using some algae extract (e.g., carrageenan, a thickening agent, is used in many ice creams and is extracted from the red alga Chondrus crispus) or some other basic function (e.g., algae produce over half of the oxygen in the atmosphere!). Sylvia Lee's already written about "What is algae?" so I won't elaborate beyond "the bulge" (as above). But, instead, what's the big deal about algae in the Everglades? Well, you're going to have to stay tuned for next week's (?) episode of Nick's Wonderful World of Algae. I see you all waiting as eagerly for it as for new episodes of The Walking Dead or Game of Thrones, etc. But what about The Walking Algae or Game of Cyanos?

A teaser: I mentioned algae on manatees. Dr. Tom Frankovich from FIU has actually looked into diatoms that live on manatees 'round these parts - super cool stuff. You may have noticed manatees that look a bit mossy. Let's amend that to "algae-y" and start singing, "Algae met a manatee. The manatee met algae." And they lived happily ever after.

D'aww. From: Fish and Wildlife Service

Tags # Algae # Carbon # climate change Continue Reading

Tuesday, November 18, 2014

The Wonderful World of Diatoms

vivien November 18, 2014 0

I admit that I ended that last post a bit unclear. But diatoms, it should be said, aren’t (or, rather, shouldn't be said since I shouldn't use double negatives. Ah, well.).

http://tmagazine.blogs.nytimes.com/2014/09/16/diatomist-film-matthew-killip-premiere/?_php=true&_type=blogs&smid=nytcore-ipad-share&smprod=nytcore-ipad&_r=0

Not physically, that is; you see, diatom cell walls are made of silica (glass), and that feature is actually incredibly important (not to mention gives rise to beautiful 'micromanipulations' like this one by Klaus Kemp - different colors in part because of different thicknesses of their glass). Diatoms arose between 180 and 225 million years ago – youngsters in the algal world (compare that to the geezer cyanobacteria of 3+ billion – way vintage) – and in so doing utilized an under-used, widely available resource that set them apart. The genealogy (or “systematics”) of diatoms has since expanded to include anywhere from 20,000 to over 1 million species that span almost every aquatic or semi-aquatic habitat imaginable – oceans, lakes, rivers, moss, soil. In those habitats they can be suspended in the water column, anchored onto plants or rocks, and moving through the soil. And the species diversity of diatoms is mirrored by their physical diversity: some are round (‘centric’ – shaped like a barrel), others needle-like (‘pennate’), others bent or otherwise contorted (‘yogis’ – don’t quote me on that, though! Those are really just rebellious pennates), all of them in a variety of shapes and sizes. They are unicellular (just like, say, a red blood cell. Only they can be just as small as a red blood cell [~7 micrometers] or over 20 times as large!). Their glass cell walls are adorned with tiny holes in very distinct patterns, glass thickness varies, spines might protrude, a slit used to move may vary in shape and placement. And what’s cool is that you can use all these miniscule features to differentiate species based on appearance alone – quickly and relatively inexpensively (with the right training and tools – mostly a good microscope and a literal library of reference material. I hope you know German, though [the language of some of the best reference texts]!). So the take-home is that diatoms can be identified based on species’ unique cell wall ornamentation (a Who’s Who Among Diatoms in American Rivers and Lakes, if you will. Now that's a taxonomy textbook title!), and that allows us to figure out who’s where and why.

Tom-ay-to, tom-ah-to.

And understanding who’s where lets us use diatoms as very dependable indicators for ecosystem changes. Diatoms are sensitive and like what they like (what's that on the Myers-Briggs Type Indicator? ISFP?). They often fill very specific roles in their communities, and if something happens to the environment – changing temperatures, physical disturbance, nutrient enrichment – then the diatoms, and other algae, are among the first to respond. So you can catch the effects of, say, agricultural runoff into a lake early on if you look at how the algae changes. And arguably the best algae for noting that change is the diatoms because of their diversity, ID-ability, and preservability. Because glass tends to linger in most conditions we can even take a soil core of that 'polluted' lake and examine the diatoms from years past to then model and understand what past conditions were like! Their cell wall ornamentation is preserved, allowing us to still identify their dead ‘shells’ (properly, “frustules”) – a natural preservation that we replicate in the lab by killing modern diatoms so we can look at just their glass frustules to make identification easier. Talk about bio-indicators (and cruelty to diatoms). And that diversity within and among habitats allows us to use diatoms to answer some very fundamental ecological questions involving metacommunity diversity and microbial dispersal and biogeography (I know, I know: those will be discussed in entirely separate posts to come).

And I’m just getting started (“Oh, no,” you’re thinking.). I’ll be quick. Going back to the uninformative reasons of why they’re awesome, some clarification. Diatoms alone produce around anywhere from 25 to 40% of Earth’s oxygen and are large carbon sinks (translation: they gobble up that pesky carbon dioxide and give us oxygen, free of charge. So generous!). They produce oil droplets that are delicacies for primary consumers (as well as nutritious – think Flintstones gummies good) – and they have potential to be used for biofuels (they’re trying to squeeze the oil out of them. Literally.). When they died off en masse thousands of years ago (diatom genocide! Where was the UN?!) their graveyards eventually became reserves of

(or diatomaceous earth), which is great if you like clean teeth (as an abrasive) and beer (as filters) and don’t like ants in your house (natural pesticide). But even when they’re alive some species secrete vast amounts of 'mucus' around them that invite all sorts of other creatures (mainly bacteria, fungi, and/or other algae) to party and form a biofilm, which have even more ecosystem benefits (outside of making you fall on your face in a lake)! Imagine coating yourself in your own snot and letting stay anything that wants to use, eat, or add onto that snot (not quite a perfect example of the intricacies, but what a vivid picture for the general idea! That makes the "affectionate" term of "rock snot" for biofilms of the diatom Didymosphenia geminata even apter, eh?).

Didymosphenia geminata biofilm

I realize that all of this may be a little too general to be overly informative, but my hope is that it piques your interest in learning a bit more about diatoms – whether scientist or enthusiast. In the Everglades we’re using diatoms to look at ecosystem-scale effects of sea level rise on the Everglades. Diatom indicator species of nutrient enrichment are used in assessing the efficacy of Everglades restoration and conservation. We see poignant applications of diatom science right here in South Florida that are visible all the way up to reports to Congress! (Mastogloia smithii Goes To Washington, anyone? Though Sylvia Lee may have something to say about that nomenclature!)

But in all this excitement about diatoms it’s important to recognize algae as a whole. Cf. T. jeffersonii (invalid, illegitimate, and insane taxonomy?) doesn’t agree with discrimination, remember. So to rectify this miscarriage of algal civil rights, stay tuned for the next installment of the Wonderful World of Algae! (Will there be death? Will there be destruction [of tasteful writing, yes! Of algae…?]? Will there be adorable pictures of sea otters on an Everglades research page? Find out next week!)

This blog post was written by Nick Schulte, a Master's student in Evelyn Gaiser's lab at FIU.

Tags # Algae # Diatoms # Ecology Continue Reading

Tuesday, January 7, 2014

Exploring the Outer Reaches of the Everglades

vivien January 07, 2014 0

This post was written by guest blogger Emily Nodine, a PhD candidate in FIU's Periphyton Lab (http://algae.fiu.edu/research/).

When people think about today’s Everglades or the “River of Grass,” they generally think of Lake Okeechobee, Everglades National Park, and the canals and water control structures in between. But the watershed is actually much larger than that. Lake Okeechobee does serve as the headwaters of the Everglades; prior to human alteration, Lake Okeechobee would slowly overflow southward during very wet periods, forming the shallow, slow-flowing sheet of water that earned it the title “River of Grass.” Today, the Hoover Dike prevents this and the water flow is strictly controlled, mostly released to the east and west coasts via the St. Lucie and Caloosahatchee Rivers, but also southward to the Everglades through an extensive system of canals and water control structures. But the water in Lake Okeechobee came from somewhere else, too.

Lake Okeechobee sits at the mouth of the Kissimmee River and several smaller creeks that drain much of highlands central Florida as far north as Orlando. Much like Lake Okeechobee and the Everglades, the Kissimmee River has also been through dramatic hydrological alteration and subsequent restoration efforts. Once a meandering 103-mile waterway with a floodplain 1 to 3 miles across, the Kissimmee River was transformed during the 1960s to a 56-mile canal 300 feet wide and 30 feet deep. Within the next couple of years, the South Florida Water Management District and U.S. Army Corps of Engineers plan to complete backfilling of a large section of the canal and removing water control structures in order to restore ecological integrity to 40 square miles of the river-floodplain system and 12,000 acres of wetlands. Already, flora and fauna that disappeared following the canalization have begun to return. Additional details about the restoration project can be found at http://my.sfwmd.gov/portal/page/portal/xweb%20protecting%20and%20restoring/kissimmee%20river.

Little of the Everglades watershed has been left untouched by hydrological alterations. While restoration efforts such as the one-mile bridge on Tamiami Trail aim to deliver more water southward to the Everglades, estuaries at the outflows of the St. Lucie and Caloosahatchee Rivers suffer from the effects of too much freshwater. Historically, the Caloosahatchee River’s headwater was a small wetland pond west of Lake Okeechobee called Lake Hicpochee. During early efforts to drain the Everglades for farmland in the late 1800s, a canal was dug connecting Lake Hicpochee to Lake Okeechobee, allowing the Caloosahatchee to become a major outflow for the larger lake. Through subsequent canalization and installation of water control structures, the Caloosahatchee, like the Kissimmee River, was transformed. Today, freshwater is released through a series of lock and dam structures down the Caloosahatchee to relieve pressure on the aging Hoover Dike that surrounds Lake Okeechobee, causing an influx of eutrophic water to the Charlotte Harbor estuary that results in adverse effects on seagrasses, oyster beds, and water quality.

My research is focused on the Charlotte Harbor watershed, which sometimes feels peripheral to the work of FCE LTER scientists in the Everglades, but I remind myself how important this region is as part of the Greater Everglades Ecosystem. There are three major inflows into Charlotte Harbor, and they couldn’t be more different. The Caloosahatchee, which is near my home, is highly managed and cut off from marine influence by water control structures (except during severe storms, when these are occasionally breached); the Peace River, which is naturally enriched in phosphorus and has been extensively mined for fertilizer; and the Myakka River, which is relatively pristine, with much of its watershed set aside as conservation lands and parks.

My goal is to understand the differences among these systems and how they influence inputs to Charlotte Harbor over time. I am studying the diatom communities across this watershed in order to interpret long term changes from sediment cores taken from the estuary. Diatoms are single-celled algae that provide clues about past environments because they are indicators of specific environmental conditions and they preserve in sediments, allowing us to determine what past conditions were based on which diatoms are present. Specifically, I am interested in how they are distributed along environmental gradients, and how this changes in response to a disturbance such as a tropical storm or hurricane. By studying what diatoms occur in these waterways before and after storms, I hope to identify a signal of hurricane activity that can be detected in sediment cores and help us to understand how these types of storms have affected south Florida ecosystems on large time scales.

Tropical Storm Debby, in June 2012, provided an excellent opportunity to investigate changes across the watershed. During the dry season, diatom assemblages are strongly related to a salinity gradient across the watershed. But following the storm, diatom communities changed in different ways across the various regions of the watershed. Next, I hope to identify patterns in these differences to help us understand drivers of the type or direction of changes, such as whether anthropogenic alteration causes a different response to disturbance compared to more pristine areas.

Tags # conservation # Emily Nodine # Myakka River Continue Reading

Tuesday, September 10, 2013

Three new Everglades diatom species named

vivien September 10, 2013 0

Recently, my colleagues and I named three new Everglades diatom species after much morphological analyses and taxonomic detective work. While the Everglades diatom community may not be as species-rich as lakes in more temperate environments, there are many species waiting to receive a proper name and publication. The reason that so many species continue to be called "species number 17" or "looks like this other species but not quite" is because there just has not been the kind of focused taxonomic research here in subtropical and tropical places in the Western hemisphere. Contrast this to the hundreds of years of research on European diatoms. The Everglades diatom community offers great opportunities for graduate students, like me, to investigate and describe new species!

Everglades periphyton with four live cells of Mastogloia calcarea at 1000x magnification

For the FIU News article, click here:
http://news.fiu.edu/2013/09/algae-researcher-names-three-new-species-in-the-everglades/66963

For additional pictures of the new species, see below:
All scanning electron micrographs are credited to Dr. Bart Van de Vijver. Solid lines on the images indicate 10 micrometers (0.01 millimeters).

Mastogloia calcarea - light micrographs of a single specimen at two different focus levels and scanning electron micrographs of two specimens showing the exterior and interior of the cell. This diatom is the most dominant species in Everglades periphyton. It has long been mistaken for Mastogloia smithii or M. smithii var. lacustris because original material for these two taxa were not accessible for accurate comparison with the Everglades taxon.

Mastogloia pseudosmithii - light micrographs of a single specimen at two different focus levels and scanning electron micrographs of two specimens showing the exterior and interior of the cell. This diatom is similar to Mastogloia smithii because of its elliptical shape but has completely different patterning on the exterior and has completely different internal ultrastructure.

Envekadea metzeltinii - light micrographs and scanning electron micrographs of four specimens showing different sizes and the exterior and interior of the cell. This diatom is part of a recently erected genus identified by the sigmoid shape of the raphe (slit that goes through the center) and the irregularly shaped areolae (holes on the cell surface).

The Mastogloia species will be published in the journal Diatom Research.

Envekadea metzeltinii was published in the journal Phytotaxa and can be accessed through the following doi: http://dx.doi.org/10.11646/phytotaxa.115.1.2

For even more detail about this species, visit the Diatoms of the United States website:

http://westerndiatoms.colorado.edu/taxa/species/envekadea_metzeltinii

Tags # Diatoms # Periphyton # Sylvia Lee Continue Reading