Diatom Forest as Water Quality Indicator: H2O Publishes my Illustration

My original illustration for my article on Diatom Forests

 

This past spring, Dutch scientist Herman van Dam (Consultancy for Water and Nature) approached me for permission to use my illustration of the diatom forest in a paper he and co-authors were preparing for the Dutch journal H2O. He explained that they wanted to help familiarize water managers who read the journal with the underwater biodiversity for which my illustration would be helpful.

 

The Illustration

 

He’d seen my illustration in my article “A Diatom Spring” in The Meaning of Water. Below is a summary of my article about the diatom forest:

 

Attachment and colonization starts with a ‘clean’ unpopulated surface (usually scoured by turbulence in a storm or some other event or a new surface tumbled into the water). Several stages of succession take place, starting with early colonizers. The adnate Cocconeis placentula, whose frustules attach directly to the substrate, is an example of an early colonizer. When they attach to a substrate they form a biofilm (think moss in a terrestrial forest). Adnate species are eventually overgrown by taxa that produce a mucilaginous pad (e.g. Synedra) or stalk (e.g. Gomphonema). The understory layer is typically occupied by diatoms such as Fragilaria vaucheriae and Synedra radians that attach to the surface at one end (apical) of their rod-shaped frustules using a mucilaginous pad to form “rosettes” that resemble spiky understory shrubs. This allows them to protrude above the adnate taxa and take advantage of more light.

Fragilaria and Synedra forming "rosettes" on substrate

 

The diatoms Cymbella and Gomphonema produce long stalks that attach directly to the surface, allowing them to form a swaying canopy over the lower tier of cells of Fragilaria vaucheriae, Synedra radians and early colonizer Cocconeis placentula whose frustules attach directly to the substrate (think overstory and understory of a terrestrial forest or a marine kelp forest).

SEMs of colonizing stalked diatoms

 

The Diatom Forest Structure

 

Just like trees, the canopy-forming stalked diatoms effectively compete for available light and nutrients in the water with their vertical reach. They provide the ‘overstory’ of the diatom forest’s vertical stratification. These tree-like diatoms also provide an additional surface for other diatoms to colonize (e.g. tiny epiphytic Achnanthes settle on the long stalks of Cymbella, just as lichen does on a tree trunk).

 

The stalked diatom forest acts like a net, trapping drifting-in euplankton, such as Pediastrum sp. andFragilaria spp., which then decide to stay and settle in with the periphyton community. The mucilage captures and binds detrital particles in both lower and upper stories of the diatom forest; these, in turn, provide nutrients for the diatom forest and additional surfaces for colonization. In their work with periphyton communities, Roemer et al. (1984) found several diatoms (e.g. Diatoma vulgare, Fragilaria spp. Stephanodiscus minutula) entangled in the complex network of cells, stalks, and detritus of the diatom forest’s upper story. They also found rosettes of Synedra radians—like jungle orchids—attached to large clumps of sediment caught by the net of mucilage.

 

Eventually, ‘overgrowth’ occurs as the periphyton colony matures and grows ‘top-heavy’ with all this networking. The upper story of the community simply sloughs off—usually triggered by turbulence in a river from rains, storms, or dam release. This is similar to a forest fire in the Boreal forest, which creates space and light for new colonization and growth. The dislodged periphyton ride the turbulent flow, temporarily becoming plankton, and those that survive the crashing waters provide “seed” to colonize substrates downstream. Others may get damaged and form the ‘dish soap’ like suds or foam you often see in turbulent water. The proteins, lignins and lipids of the diatoms (and other associated algae) act as surfactants or foaming agents that trap air and form bubbles that stick to each other through surface tension.

 

My illustration adapted by H2O in Dutch

The Paper

 

The paper was published June 13, 2024, in H2O, written by Jako van der Wal, Joep de Koning and Herman van Dam, and entitled “Snel inzicht in de ecologische waterkwaliteit met diatomeeën”(Quick insight into ecological water quality with diatoms).This paper was right up my alley! As a diatom specialist and limnologist who studied them in relation to environmental conditions and perturbations, I was intrigued by the paper and gained some additional insight on diatom ecology. 

 

Van der Wal et al. cited recent advances in DNA-based identification methods that provide fast and cheap diatom identification over the traditional method of using an optical compound microscope to observe morphological characteristics such as size, shape and ornamentations of the silicified cell wall. I can attest that this is a labour-intensive process in which I spent many hours and days hunched over a microscope during my masters research at Concordia University. This efficient DNA-identification has seen a resurgence of using diatoms as a valuable tool for water quality managers, with applications providing insight into both current and historical water conditions. The authors argue that benthic diatoms or periphyton(living on substrates such as plants, rock, sand and artificial surfaces) have been since the 1980s used as indicators of saproby, trophy, acid and salt character in, among other things, ditches and canals. For every type of water and water quality, there are diatoms that have their habitat there, write the authors. They argue that, unlike phytoplankton, fish and macrofauna, periphyton attach to a surface and hardly move; this means that effects of water quality can be demonstrated locally. Because many diatom species tolerances and intolerances are known and they reproduce quickly (over days), diatoms respond quickly to changes in the environment—much faster (often within weeks) than other ecological indicators. 

 

Scientists and water technicians can use diatom species composition to measure perturbations by organic material, low oxygen content, eutrophication, and toxicity. Given that diatoms colonize and develop quickly, this includes unstable and damaged habitats where other indicators cannot develop, such as shipping traffic, waves or where cleaning or dredging is carried out regularly. Historical insight can be provided by diatoms, given that their silica frustules are naturally preserved in sediment. 

Diatoms and organics form froth of bubbles on shore rocks

 

My Own Work with Turbulence

 

During my masters research in several streams in the Eastern Townships, I examined how diatoms colonized artificial substrates; how they formed productive biofilms that sustained an entire periphyton community of attached aquatic life and discovered that their pattern of colonization related to current speed and direction. I submerged glass slides (the kind people use to look at critters under the microscope) in a device in the stream and oriented them parallel or perpendicular to the current.

Microscope slides with periphyton growth after immersion in a stream 

 

There are two ways an algal community grows in a new area: (1) by initial colonization and settling; and (2) by reproduction and growth. I studied both by collecting slides exposed for differing lengths of time (collecting young and mature communities) in different seasons.

Nonrandom diatom colonization across a microscope slide

I discovered that the diatoms colonized these surfaces in weird ways based on micro-turbulence. Early colonizers, like Achnanthes and adnate Cocconeis preferred to settle on the edges of the slides, where the chaos of turbulence ruled over the sheer of laminar flow. They colonized by directly appressing to the substrate, making them the first photosynthetic taxa to establish a biofilm on a clean substrate. Vadeboncoeur and Katona (2022) write that “in waved-washed surfaces, these taxa may be the only algae that persist.” I postulated that the drift velocity was reduced on the slide’s edge, where turbulence was greatest, giving drifting algae a greater chance to collide and settle on the slide over the more shear laminar flow along the slide’s central face.

 

Once settled, the community was more likely to grow with turbulence. Greater turbulence decreases the diffusion gradient of materials around algal cells, with a higher rate of nutrient uptake and respiration. Turbulence provides greater opportunity to an existing colony by increasing “chaotic” flow, potential collision and exchange. Turbulence is a kind of “stable chaos” that enhances vigor, robustness and communication.

 

Diatom and organic scum below a dam

 

Using Diatoms in Water Quality Assessments

 

Van der Wal et al. argued that in environmental assessment the DNA-identification is just one step in a process that looks a population structure and health. Diatoms are already used in 21 of the 27 EU countries as part of a Water Framework Directive (WFD) quality index for flowing waters and in nine EU countries for standing water. Example conditions and associated perturbations where diatoms are a particularly useful indicator include: salinity, acidity, oxygen saturation, organic load (saproby), nutrient richness (trophy), temperature, and toxicity.

 

Diatom Growth Forms & Deformities

 

Van der Wal et al. argue that in addition to the different species compositions and the related ecological indices, growth forms and deformations of diatoms are useful indicators of water quality, particularly in relation to specific toxins.

 

Growth forms of diatoms can be described as attached, short-stalked, long-stalked, mobile and living in mucous tubes (Figure 3, van der Wal et al., 2024). Each growth form has advantages and disadvantages. For example, short-stalked diatoms are more difficult to graze and long-stalked diatoms come into contact with more water, from which they can then absorb substances. Long-stalked diatoms can also absorb more light if there is a lot of competition. Mobile diatoms can adapt to changing conditions by, for example, migrating from surface to subsurface and vice versa. Diatoms in slime tubes are more difficult to prey on and respond more slowly to environmental changes.

 

Van der Wal et al. cited work by Rimet & Bouchezwho found that long-stalked diatoms decline in waterbodies subjected to various pesticides. Falasco et al. also observed diatom deformities when exposed to various toxic substances. Heavy metals were observed to cause deformities in Navicula and nitrogen toxicity was also implicated in diatom deformities. 

Navicula sp. frustule on the right shows deformed striations

 

 

References: 

 

Falasco, E., Ector, L., Wetzel, C.E., Badino, G. & Bona, F. (2021). “Looking back, looking forward: a review of the new literature on diatom teratological forms (2010-2020).” Hydrobiologia 848: 1675-1753.

 

Munteanu, N. 2-22. “When Diatoms Create a Forest.” https://themeaningofwater.com. December 18, 2022.

 

Munteanu, N. 2023. “When Diatoms Bloom in Spring.” https://themeaningofwater.com. May 14, 2023.

 

Munteanu, N. 2023. “A Diatom Spring.” https://themeaningofwater.com. April 16, 2023.

 

Munteanu, N. & E. J. Maly, 1981. The effect of current on the distribution of diatoms settling on submerged glass slides. Hydrobiologia 78: 273–282.

 

Munteanu, Nina. 2016. “Water Is…The Meaning of Water.” Pixl Press, Delta, BC. 584 pp.

 

Poikane, S., Kelly, M., & Cantonati, M. (2016). ‘Benthic algal assessment of ecological status in European lakes and rivers: challenges and opportunities’. Science of the Total Environment 568: 603-613. 

 

Rimet, F. & Bouchez, A. (2011). ‘Use of diatom life-forms and ecological guilds to assess pesticide contamination in rivers: Lotic mesocosm approaches’. Ecological Indicators 11: 489-499.

 

Roemer, Stephen C., Kyle D. Hoagland, and James R. Rosowski. 1984. “Development of a freshwater periphyton community as influenced by diatom mucilages.” Can. J. Bot. 62: 1799-1813. 

 

Serôdio, J. & Lavaud, J. (2020). “Diatoms and their ecological importance”. In: Leal Filho, W. et al. (eds). Life below water. Encyclopedia of the UN Sustainable Development Goals (pp.1-9). Springer Nature.

 

Smolar-Zvanut, Natasa and Matjaz Mikos. “The impact of flow regulation by hydropower dams on the periphyton community in the Soca River, Slovenia. Hydrological Sciences Journal 59 (5): 1032-1045.

 

Wal, J. van der, Joep de Koning and Herman van Dam. 2024. “Snel inzicht in de ecologische waterkwaliteit met diatomeeën”  H2O, 13 June, 2024.

Wood, Allison R. 2016. “Attached Algae as an Indicator of Water Quality: A Study of the Viability of Genomic Taxanomic Methods.” Honors Theses and Capstones. 306. University of New Hampshire Scholars’ Repository.

 

Zuilichem, H. van, Peeters, E. & Wal, J. van der (2016). “Diatomeeën als indicator voor waterkwaliteit nabij rwzi's”. H2O-Online, 9 december 2016. https://edepot.wur.nl/401202 

Diatom and organic froth on a river below a dam

Nina Munteanu is a Canadian ecologist / limnologist and novelist. She is co-editor of Europa SF and currently teaches writing courses at George Brown College and the University of Toronto. Visit www.ninamunteanu.ca for the latest on her books. Nina’s bilingual “La natura dell’acqua / The Way of Water” was published by Mincione Edizioni in Rome. Her non-fiction book “Water Is…” by Pixl Press(Vancouver) was selected by Margaret Atwood in the New York Times ‘Year in Reading’ and was chosen as the 2017 Summer Read by Water Canada. Her novel “A Diary in the Age of Water” was released by Inanna Publications (Toronto) in June 2020.

Nina Munteanu’s “Robin’s Last Song” in Metastellar Magazine

My short story Robin’s Last Song was republished recently in the superlative online magazine Metastellar. The story had first been published in 2021 in Issue 128 of Apex Magazine. An earlier version of the story called Out of the Silence appeared in the literary magazine subTerrain Magazine Issue 85 in 2020. 

 

I raced up the stairs to the auditorium then quieted my breath and listened at the door, heart thumping like a bird trying to escape. Professor Gopnik was ten minutes into his lecture; I could hear his commanding voice: “… estimates that the entire number of birds have been reduced by a third in five decades—I mean common birds like the robins, sparrows, warblers, and even starlings…”

He was talking about Rosenberg’s paper in Science. The study shocked the scientific community; but I had already observed the decline of the house sparrow around my aunt and uncle’s house near the Old Mill. And the robin—my namesake, whose song heralded spring for me—had grown quiet.

I imagined Gopnik waving the journal at the class in his typical showman style. He had a habit of wandering the stage like an evangelist, fixing each student with intense blue eyes as if challenging them to believe. I thought him an over-confident condescending prig. But for someone who looked as young as the students he was teaching, Gopnik was brilliant. And what he was doing was so important. I wanted so badly to work under him as a grad student. But he terrified me.

 

The Story Behind the Story

 

It all began with my discovery of an emerging bioacoustic tool, soundscape ecology, that measures biodiversity and ecosystem functionality. I’d just read the disturbing 2019 Science article by Rosenberg and team who determined that our slow violence of habitat degradation and toxic pollution has reduced the world’s bird population by a third in just five decades. I was devastated; I could not imagine a world without the comforting sound of birds. What would it be like if all the birds disappeared?

 

Already primed with research into genetic engineering for the sequel to my 2020 eco-novel, A Diary in the Age of Water, my muse (often delightfully unruly) played with notions of the potential implication of gene hacking in ecological calamity and how this might touch on our precious birds: when nature “is forced out of her natural state and squeezed and moulded;” her secrets “reveal themselves more readily under the vexations of art than when they go their own way.”

 

Robin’s Last Songis a realizable work of fiction in which science and technology are both instigators of disaster and purveyors of salvation. Today, gene-editing, proteomics, and DNA origami—to name just a few—promise many things from increased longevity in humans to giant disease-resistant crops. Will synthetic biology control and redesign Nature to suit hubris or serve evolution? What is our moral imperative and who are the casualties? As Francis Bacon expressed in Novum Organum, science does not make that decision. We do. 

 

 

You can read an Interview on Writing Robin’s Last Song that Alberta author Simon Rose did with me recently.

 

I also recently sat down with Rebecca E. Treasure of Apex Magazine for a conversation about story, ecology, and the future. Here’s how it begins:

 

Apex Magazine: The Way of Water in Little Blue Marble is such a powerful piece touching on water scarcity and friendship, a dry future and the potential for technology to overtake natural ecology. Robin’s Last Songexplores extinction, human fallibility, friendship, and again, that conflict between technology and nature. Do you think we’re heading toward the kind of dystopia shown in these stories?...

 

For more about bird declines around the world see my articles: “What if the Birds All Die?”

and “Birds are Vanishing.”

 

“Over increasingly large areas of the United States, spring now comes unheralded by the return of the birds. The early mornings are strangely silent where once they were filled with the beauty of bird song.”—Rachel Carson, Silent Spring

 

Read my other stories in Metastellar here: Nina Munteanu in Metastellar Speculative Fiction and Beyond. 

Nina Munteanu is a Canadian ecologist / limnologist and novelist. She is co-editor of Europa SF and currently teaches writing courses at George Brown College and the University of Toronto. Visit www.ninamunteanu.ca for the latest on her books. Nina’s bilingual “La natura dell’acqua / The Way of Water” was published by Mincione Edizioni in Rome. Her non-fiction book “Water Is…” by Pixl Press(Vancouver) was selected by Margaret Atwood in the New York Times ‘Year in Reading’ and was chosen as the 2017 Summer Read by Water Canada. Her novel “A Diary in the Age of Water” was released by Inanna Publications (Toronto) in June 2020.

Nina’s “Favorite 3 Reads Of 2023: Feminist Eco-Fiction

In late 2023, I was invited by Shepherd to post an article of my favourite three reads of 2023. I had earlier posted on Shepherd an article describing what I considered to be the best eco-fiction books that make you care and give you hope.

 

I started out by reviewing what I had read in 2023. It looked like I’d read about thirty odd books, almost half and half non-fiction to fiction. That’s not many, but I’m a slow reader. I pore through each book at a snail’s pace, spending time making notes with some, particularly the non-fiction books, which I use to research my writing. With fiction, I dive in deep and thoroughly savor each word and sentence like a mouthful of an excellent meal made with loving hands. Books varied from non-fiction scholarly works on forest ecosystems (The Treeline by Ben Rawlence) and post-capitalism (Four Futures by Peter Frase) to literary fiction, political thrillers, speculative fiction, clifi, and eco-fiction.

 

It was a tough choice, but I came up with three choices and a thematic rationale that resonated with me and made a deep kind of sense for that year: all three books were eco-fiction of sorts and featured hopeful stories of strong women, acting out of compassion and in solidarity with intelligence, kindness and courage. For me, 2023 was a year of strong feminine energy for the planet and my favourite books reflect that. Here they are (read the original article on Shepherd here): 

 

 

The first of my favourite three books of 2023 is Michelle Min Sterling’s Camp Zero.

 

Set in the remote Canadian north—a place I love for its harsh beauty—this feminist climate fiction explores a warming climate through the perilous journeys of several female characters, each relating to her environment in different ways. Each woman exerts agency in surprising ways that include love, bravery and shared community. The strength of female power carried me through the pages like a braided river heading to a singular ocean. These very different women journey through the dark ruins of violent capitalism, colonialism and patriarchy—flowing past and through hubristic men pushing north with agendas and jingoistic visions—to triumph in an ocean of solidarity. I empathized with each woman as she found her strength and learned to wield true heroism—one based on collaboration and humble honesty.

 

 

My second favourite book of 2023 is Yevgeni Zamyatin’s We.

 

I enjoyed this 1920 hopeful dystopia for its courageous and unprecedented feminism.

While the story centres on logical D-503, a man vacuously content as a number in the One State, it is I-330—Zamyatin’s unruly heroine—who stole my attention. Confident, powerful and heroic, the liberated I-330 embraces the Green Wind of change to influence D-503. A force of hope and resilience, she braves torture to successfully orchestrate a revolution that breaches the Green Wall—feats typically relegated to a male protagonist in novels of that era.When pregnant O-90 refuses to surrender her child to the State, I-330 helps her escape to the outside, where the Green Wind of freedom blows.I resonated with Zamyatin’s cautionary tale on the folly of logic without love and Nature.

 

 

My third favourite book of 2023 is Hugh Howie’s Wool (first of the SILO series).

Juliette—humble and gutsy, kind and relentlessly motivated in her journey for the truth—kept the pages turning for me. Juliette is a mechanic from the Down-Deep of the underground Silo, humanity’s last refuge to a toxic world. When Juliette inexplicably lands the job of sheriff, she treats her new position as a tool to seek the truth about her lover’s mysterious recent death. At her own peril, she pulls on threads that ultimately reveal a great conspiracy. 

 

Juliette’s literal and metaphoric rise from the Down-Deep to the Up-Top is a feminist’s journey that transcends intersectional barriers as she battles small-minded men of power and maintains her integrity by refusing to abide by the inhumane Up-Top rules of order. By the end, I sensed a victory for humankind through womankind. 

 

Also check out Shepherd’s 100 best books of 2023.

 

You might be interested in two of my own eco-fiction novels that feature several strong female protagonists:

 

Darwin’s Paradox follows the complex dynamic of a brave mother and her willful teenage daughter, both ‘gifted’ by a virus living inside them. Accused of murder and deliberately spreading the virus that killed many, Julie fled the enclosed city and settled in the climate wastelands with her husband and their child. Years later, when their harsh refuge is threatened by city forces seeking mother and daughter for experimentation, Julie leaves her family and gives herself up to the city, hoping they will abandon pursuing her daughter. Still psychically connected to the city’s AI community (now evolving into an autonomous entity with the intelligent virus), Julie tangles with political intrigue while her daughter, who followed her to the city, stumbles into her mother’s violent past.  

 

A Diary in the Age of Water follows the climate-induced journey of Earth and humanity through four generations of women, each with a unique relationship to water. Centuries from now, in a dying boreal forest in what used to be northern Canada, Kyo, a young acolyte called to service in the Exodus, yearns for Earth’s past—the Age of Water—before the “Water Twins” destroyed humanity. Looking for answers and plagued by vivid dreams of this holocaust, Kyo discovers the diary of Lynna, a limnologist from that time of severe water scarcity just prior to the destruction. In her work for a global giant that controls Earth’s water, Lynna witnesses and records in her diary the disturbing events that will soon lead to humanity’s demise.

 

Nina Munteanu is a Canadian ecologist / limnologist and novelist. She is co-editor of Europa SF and currently teaches writing courses at George Brown College and the University of Toronto. Visit www.ninamunteanu.ca for the latest on her books. Nina’s bilingual “La natura dell’acqua / The Way of Water” was published by Mincione Edizioni in Rome. Her non-fiction book “Water Is…” by Pixl Press(Vancouver) was selected by Margaret Atwood in the New York Times ‘Year in Reading’ and was chosen as the 2017 Summer Read by Water Canada. Her novel “A Diary in the Age of Water” was released by Inanna Publications (Toronto) in June 2020.