Category Archives: Water


I’m in northwestern Ontario, paying a visit to some long-buried ancestors. As a bonus, I get to experience some chilly weather

Here’s what happens to a waterfall in a chilly breeze at -25 (-13 Fahrenheit):

The lip of Kakabeka Falls in summertime...

The lip of Kakabeka Falls in summertime…

...and in the winter. All motion ceases.

…and in the winter. All motion ceases.


Some of the upstream river is still unfrozen and it slides behind the “ice falls,” briefly appearing in a pool below, before diving back down.

All this is very impressive, but the birds and mammals are even more staggering. Chickadees bounce among the branches, a goshawk chatters, ravens wing by, and red squirrels are out foraging. I took off my gloves (idiot) to snap a few bird photos. One minute later, the wind and cold did their work and I lost all feeling in my thumb. Its skin still tingles, hours later.

I salute you, boreal masters of mikwan, ice.


Black-capped chickadee

Pine grosbeak

Pine grosbeak

Ice flowers in Shakerag Hollow

The temperature dropped to minus five last night (minus twenty for disciples of Anders Celsius), the coldest that I’ve seen in Sewanee. I took a walk in Shakerag Hollow this morning to see how the woods were faring in this unusual chill. I’ve never experienced such silence here. The quiet was punctuated by woodpeckers drilling meager breakfasts from high in the canopy and trees occasionally snapping out gunshot sounds as their wood shattered. No sign of wrens, titmice, chickadees. The forest floor was mostly clear. Only a few deer tracks. Most birds and mammals are in hunker-down mode.

Amazingly, given the cold, the springs were still running. This flowing water created some beautiful ice formations on the rocks all around. When water vapor rises from the stream, it hits cold, dry air. This is an unstable mix, ripe for an encounter with a pointy nucleation site: an icy strand of moss or rock edge. Once they get started, these crystals build on themselves, growing “flowers” from the air. An icy foreshadow of the spring ephemerals? The largest ones are a couple of inches across. Similar formations are found in polar seas and host very unusual communities of bacteria.

So welcome to Tennessee, Polar Vortex. Here are your blooms:


…and an altogether different encounter with the waters of Colorado.

Driving south from Denver, headed to the mountains for some quality time with Rocky Mountain fossils and a campsite, the radio news interrupted my freewheeling reveries. A giant wave of mud had smashed through Manitou Springs, burying part of downtown, killing a driver on the main highway, and destroying dozens of cars and several buildings. The national news gave just a sketch, so I pulled over and got the local paper: grim news of a “massive and deadly flash flood,” caused by rain over a mountainside burn scar. The scar was left by the Waldo Canyon fire that burned 18,000 acres of land in 2012, stripping the mountains of vegetation and leaving dangerously unstable soil behind.

The paper mentioned a need for volunteers, so I put my plans on hold for a day and made a small diversion into Manitou. After signing up with a coordinator I spent several hours shoveling mud out of a basement. The flood water line was about six feet off the ground and ground level was another six feet above the creek: the flash flood was huge, almost unimaginable given the tiny rivulet – three feet across, a few inches deep — that ran in the creek bed when I was there. In the basement, ankle-deep black mud covered everything. Dozens of local residents and a motley group of volunteers dug and carried out the slurry, one five gallon bucket at a time. By day’s end, the basement was clear of ooze, if not clean. Outside, piles of mud and smashed debris were piled next to the road.


Not visible, but far worse than the physical damage, was the human cost: a life lost, homes destroyed, businesses losing both infrastructure and sales at the busiest time of year in this tourist-driven economy. And the weight of knowing that this is not the end: the burn scar remains. The Denver Post reports that this flash flood was the third of the year and ten more years remain before the scar will stop spilling soil into the canyon. All this compounds the pre-existing high flood risk in a town where many of the historic buildings are built along the creek. Local, state and federal agencies are working hard to build upstream mitigation ponds and barriers. This latest flood will spur further action, with funds more readily available now that the area is an official “disaster emergency”.

Two days later, on my return journey, I drove back into town and bought some breakfast. Bucket-carrying is one way to lend a hand; supporting local businesses is another. These are small actions, I know, not at all commensurate with the magnitude of what happened. And crushingly small when we reflect that fires and floods are projected to surge worldwide in the next decades. As I was shoveling mud, unbidden memories and images came roiling up. The smell of dead animals and endless miles of devastation in southern Mississippi after Katrina, tales told by Haitian friends of awful mudslides in their hometowns, images of New York subways inundated after Sandy. Bucket and breakfasts seem mighty, mighty small.

Turtle tracks

Tracks left by young snapping turtle. Body length, about two inches. May 1st, Sewanee TN.

Tracks left by young snapping turtle. Body length: about two inches. May 1st, 2013, Sewanee TN. Habitat: puddle on gravel road between Alabama and Willie Six Avenues.

loggerhead crawl2

Tracks left by adult female loggerhead sea turtle. Body length: about forty inches. July 6th, 2012, St Catherine’s Island, GA. Habitat: large salty puddle between America and Africa.

Happy New Year from the Blue-spotted Mudskipper

One of the many delights of working with Sewanee’s students is the biodiversity that they bring to my desktop. Sometimes, these species arrive on my actual desktop (snails, leaves, dead coots, live hummingbirds, and so forth…), but species also arrive via the glow of the screen. Here is one such arrival. I’m posting it for no other reason than the smile it brought to my face. Thank you, Dr. Bert Harris (Sewanee class of 2006 — a great vintage), for sharing this after a recent research trip to Sumatra. Without further ado, the blue-spotted mudskipper:


These air-breathing fish live in the mud flats of Asia. Males come out of their burrows to joust each other and to perform leaping dances for females. You can read more about their biology here and here.

What these websites will not explain is why they make me slightly nervous: I get the sense that they are ready to step in and take over when the current gaggle of tetrapods finally gives up the ghost. Give these mud-skippers three hundred million years and they’ll be strutting around with sapiens after their names. So this New Year, let’s look sharp and keep focused. We have competition.

Addendum: Thank you to Karen C. Rio for pointing me to this video of the mudskippers in action :)

Fifty Shades of Grey: Woodland Edition

Sitting in the woods with my class last week, I was struck by how grays had come to dominate. The light environment is transformed. Of course, a “fifty shades” wisecrack had to work its way into my impromptu lesson on the visual aesthetics of the forest. The witticism turned into a small project for my walks of the last week: pay attention and find these shades. So here they are, fifty photographs of variations on the theme.

Gray is the most egalitarian of hues. Indeed, its essence is that is not a single color. Instead, gray gives us a muted echo of all the light spectrum, a moody version of white. Contrast this with the bias of other pigments — reds, blues, yellows — that reflect just a tiny slice of the light available to them.

Gray is an unassuming mirror of the world and a quiet companion for its more assertive kin. It absorbs metaphors with ease, having combined light and dark: ash, silver, lead, pepper. A suitable tone, then, for winter reflections.

Happy Solstice, fellow ramblers.

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Wrestling with privet on Bluebell Island

Sharp blades and muscles: These are the lab tools used lately by my class. We’ve been mapping and eradicating privet from Bluebell Island, a local hotspot for wildflowers. Privet is a non-native invader and it overshadows and kills native plants.

Setting up the mapping transect.

Setting up the mapping transect.

The View from Lazy Point used as a field clipboard. The class  combines field work with discussions of readings, so hardback books find multiple uses. I hope Carl Safina would approve.

The View from Lazy Point used as a field clipboard. The class combines field work with discussions of readings, so hardback books find multiple uses. I hope Carl Safina would approve of the students’ improvised use of his fabulous book.

This project started in 2001 when my Ecology class measured and mapped every privet stem on the east side of the island where the flower populations are concentrated. I repeated the project in 2007 with my Seminar in Ecology and Biodiversity, then this year with the Advanced Ecology and Biodiversity class.

We uproot the privet plants...

We uproot the privet plants. Easy to do when they are small…

...not so easy when they are big. Katie pulled this one by hand. All that work on the swim team has paid off.

…not so easy when they are big. Katie pulled this one by hand. All that work on the swim team has paid off. No need to pull out the saw.

We’re building an interesting dataset. There are not too many places where we have long-term data on the details of how invasive plants respond to attempts at control. Along with this scientific goal, we’re hoping to leave the island in much better shape for wildflowers.

What have we found? At first glance, the project seems to be failing spectacularly. There are many, many more privet plants within the project area now than there were in 2001.

Total number of privet stems increased over time.

Total number of privet stems increased over time.

But this graph does not capture the whole story. The vast majority of the stems in 2012 are tiny little sprouts, reaching to knee-height. In 2001, the stems reached over our heads and were casting dense shade.

The number of large plants has decreased over time.

The number of large plants (>15 or 30 mm in diameter) has decreased over time.

The average (mean) size of stems decreased over time. The graph also shows that the variability in stem diameter (standard error of the mean) also decreased over time.

The average (mean) size of stems decreased over time. The graph also shows that the variability in stem diameter (standard error of the mean) also decreased over time.

So we’ve lost big plants and gained lots of little seedlings. It seems that the removal of large privet plants allows light to reach the ground which encourages both wildflowers and new privet plants. Long term success will depend on continued visits to the island to stop new privet sprouts from getting too big. The rest of the island, outside the study area, serves as an interesting contrast. It is overrun with large privet plants and the wildflower populations are dying out. Eradication of privet over the whole island would be a more major undertaking than could be accomplished by one class, even with many days’ work. Fire and goats might help.

Tyler Johnson prepared this map of the location of every privet stem (2007 data) in Dr. Chris Van De Ven's GIS class. We'll be expanding the mapping analysis in coming months to include all three sapling periods, examining whether the spatial distribution of privet has shifted over time.

Tyler Johnson prepared this map of the location of every privet stem (2007 data) in Dr. Chris Van De Ven’s GIS class. We’ll be expanding the mapping analysis in coming months to include all three sampling periods, examining whether the spatial distribution of privet has shifted over time.

Bluebell Island is owned by the South Cumberland Regional Land Trust and was bought with contributions from naturalists in Sewanee and beyond. It hosts dense populations of bluebells, trout lilies (including white trout lily), and even the rare dwarf trillium. I’m grateful to the SCRLT board for their continued support for this work, a project that started when I served on the board but has now extended for more years than I at first imagined.

Privet is not the only threat to the island’s famous wildflower display. Gill-over-the-ground is another non-native plant species that has made inroads on the island, as has exotic honeysuckle. In addition, poachers have dug significant numbers of plants over the years. About ten years ago they hit the island so hard that many parts looked as if they had been rototilled. The bluebells gradually regrew. This year, the trespassers hit again, digging large patches. I’m pretty sure that one of these patches encompasses the only known plant of the dwarf trillium in this part of Tennessee, so this rare species may now be extirpated from the island. The poachers are targeting bluebells, but the tiny trillium plant got taken as collateral damage. I may be wrong – we’ll know in the spring – but the digging crosses the exact spot where the plant lives. So if you’re tempted by the pretty bluebells for sale at the nursery, I’d advise you to skip them unless the seller can prove to you that they were nursery-propagated.

Despite the pressures, Bluebell Island is still a marvelous place. In addition to the flowers, old trees provide great habitat for woodpeckers, owls, and wood ducks. Beavers and mink swim the river. Migrant birds ply the riverbanks in the spring. Butterflies are abundant in summer. The river itself is different on every visit. It runs clear and calm in winter dry spells; swells silty and trashy in the floods; then courses bluegreen in the warm algal summer months. Suwannee is a river, but Sewanee is not; so I enjoy my visits off “the mountain” to see some real flow.

Beavers came around after us and snacked on the discarded privet stems.

Beavers came around after us and snacked on the discarded privet stems.

I’m grateful to the many cohorts of Sewanee students who have yanked, sawed, tweaked, measured, mapped, and analyzed these thousands of privet stems.

Sewanee's Bio 315 class in "gaze at the sun as if something inspiring and important was happening" pose after pulling 4275 privet stems. The largest vanquished stem is held as a trophy. We omitted the blooding ceremony.

Sewanee’s Bio 315 class in “gaze at the sun as if something inspiring and important were happening” pose after pulling 4275 privet stems. The largest vanquished stem is held as a trophy. We omitted the blooding ceremony.

Stream bows

I came across some unexpected sights on my morning walk in Shakerag Hollow. Water was snaking its way through the tangle of rocks and leaf piles that form the boundaries of the little streams on the mountain slope. As the water flowed, the barriers in its way created little falls which emptied into eddies in pools below. All this tumbling motion stirred up air bubbles that turned in slow circles on surface of the pools.

I watched this gentle gyration for some time before my eye caught what was happening below. The bubbles acted as lenses, refracting the sunlight that was coming in at a low angle through the trees. The streambed was covered in underwater stars, each one gliding behind a bubble.

As the light angled through the bubbles, its constituent wavelengths were teased out. Seen close, the stars were edged with prismatic color. Rain can bow the light, even when the rain is old and earth-bound (or, if we look forward, so young that it has not yet risen to the sky). Bubbles were not the only objects drifting on the water’s surface. Leaves and the shells of hickory nuts floated past.

One such hickory shell had some passengers, a dying caddisfly and a cluster of minute eggs encased within a blob of jelly.

I’m guessing that the eggs were deposited by an aquatic snail. (I’d be happy to be corrected or further enlightened about this guess —  I have found no adult snails in this stream which makes me suspect that I’m mistaken. Addendum: these are caddisfly eggs. Thank you David Johnson and Dave McLain for clarifing.) The caddisfly probably flew here from downstream to lay eggs in the water. The adults of many stream insects have an instinct to move upstream when they are ready to breed, counteracting the inevitable downstream flow of aquatic larvae and nymphs.

I took particular pleasure in seeing these two rafters. This is the stream that a few months ago was choked with silt from erosion on the golf course construction site. I took the eggs and the recolonizing caddisfly as signs that, although the stream is still severely impacted by sediment, some aquatic animals have persisted here and others are returning. Soon, I hope, young caddisflies and snails will join the bubbles and stars swimming and crawling in the stream’s waters.

Trash whale

As Homo plasticus shambles its clumsy way through the world, pieces of junk slough off its body. Much of this exfoliated detritus finds its way to water. The sea is now comprised of water, plastic, and life, in that order.

A collaboration among scientists, artists, and engineers at Olympic College in Bremerton, Washington, holds these facts before us in a striking way. A three-month-old gray whale hangs in the gallery, its body made from plastic bags woven into the surface of a welded armature. The baby whale swims through a room strewn with one month’s worth of rubbish collected from the shoreline along a small sampling area in Puget Sound. Toys, tags, wrappers, cups, pieces of Styrofoam, bits of houses, syringes, bottles: the downstream remnants of our appetite for indestructible plastic stuff.

The whale reminds us that many parts of our oceans contain as many bits of floating plastic as plankton. Seabird guts are choked with these fragments. Dissections of the stomachs of beached gray whales show that they also ingest large quantities of plastic. Because they feed, in part, by scooping at the sea floor, their guts get populated not just by the floating plastic, but by heavy sunken objects. And here we find a surprise: golf balls, sitting like modern Jonahs in the guts of whales. Immediately I was transported out of the gallery, away from the coast and across the continent: back to the Tennessee woods, gazing at plastic globes in a mountain forest in Sewanee.

There is no escape, it seems, from the products of our re-creation.

[Special thanks to Susan Digby, geography professor at Olympic College, one of the whale’s creators, for opening the gallery after hours to give me and my friend Peter Wimberger a tour. You can read more about the project on the gallery’s website.]

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Horror from within

The rains have brought all kinds of strangeness to the woods. As we wrapped up our surveys of stream salamanders, a cry went up: nematomorph! (Yes, this is an advanced class; in Introductory Biology the cry would have been, OMG-gross…) Lying on the stream bed was half of a Narceus millipede with a long white worm writhing its way out of the broken body. The millipede’s front legs were still grasping feebly at the ground. It had dragged itself several feet to this spot, leaving its other half discarded on the wet rocks.

This individual was not alone. Barely ten minutes later we found another, this time with both halves still encasing the emerging parasite.

I’m fairly confident that the students’ identification of the cause of this distress was correct: a nematomorph worm emerging from its host. However, the light color of the worm makes me a little suspicious that a mermithid nematode might also be the culprit. My search of the scientific literature revealed nothing about either of these worms in this particular host, so we may have stumbled into new corner of the vast wonderland of pain that is animal parasitism. We’ll likely head back down into Shakerag Hollow to see if we can find more worms to bring back to the lab.

Nematomorphs appear in the first chapter of The Forest Unseen as examples of one extreme of the continuum between cooperation and conflict. The worms eat their hosts from the inside out, with no regard for the comfort of the suffering victim. The vital organs are left in place to allow the host to continue feeding (the food goes mostly to the inner pirate, of course). At last the parasite directs its hollowed-out victim to water. There the worm breaks free, discards its dying carrier and squirms away to look for a mate.

After one of my recent public lectures, someone recently asked me for an example of what I meant by the “weight of the world’s pain” (what a blessed life the questioner must have led). This species could surely serve as an answer.

Some visceral fears are tapped when we observe the emergence from within of a life-robbing villain. I think these fears may, in part, be rooted in our species’ long history with parasites, some of which do indeed emerge through our flesh, others merely use existing exit orifices. Either way, we recoil in horror. Movie-makers titillate these deep-seated fears when they show slick-bodied monsters sliding out of our skin. And Freud et al‘s ideas of the unconscious are so successful because of our pre-existing and, ahem, unconscious fear of what might be hidden within us (oh delicious infolding circularity). Psychoanalysis entices because it promises to draw out the appalling inner worm, a cleansing that is surely the deep desire of all animals.