13 July 2023
This is Rachel’s and my first night at Trout Lake Station for the week. We are returning as Artists-in-Residence through the field station’s Drawing Water Program, almost exactly a year since our last visit. We arrived mid-afternoon, caught up with Gretchen Gerrish and Amber Mrnak, the station’s Director and Administrative Assistant respectively. We checked into our cabin, unrolled our sleeping bags, got groceries and a bite to eat. We unloaded our kayaks onto Big Muskellunge Lake at about 6:30 p.m.
We chose this lake as our first visit of the week, hoping for bryozoans. In 2022, this lake was thick with them. The bryozoans we saw last year were gelatinous green colonies that ranged from the size of an orange to about as large as a rugby ball. They floated beneath the surface like egg masses deposited by aliens. The species, Pectinatella magnifica, is thought to be native about 15 miles north of this lake, potentially making this an adventive population, though I’m not sure how meaningful such a sharp boundary is. We prowled alongside the paling of dead alder stems that extends about ten feet from the shore, blackened at the waterline. We peered down into the water. We saw only water, plants, and beetles.
I paddled to the island opposite the boat launch. The island shoreline curls around an inlet of arrowhead (Sagittaria) rosettes embedded in the mud, their roots textured with impressed rings, like the segments of an earthworm. There are some emergent leaves sprouting from these rosettes, obscurely linear at first, flattened into blades that cant backwards over the petiole, angling toward what will become the full shovel of the Sagittaria leaf at maturity. The arrowheads, like many aquatic plants, tack between life stages. Depending on the habitat, individual, or season, they shift from fully submerged to emergent, pulling nutrients from the muck, photosynthesizing beneath the surface, rising to take advantage of the easy light and oxygen above the surface for a time, then receding to the safety of the water. Arrowheads are, like almost every aquatic plant, land plants by heritage, bearing the evolutionary legacy of roughly 140 million years of angiosperm evolution and 133 million years of being monocots. When they breach the water to produce extravagant 3-petalled flowers bristling with stamens and pistils, they are wearing their early Cretaceous ancestry on their sleeves.
Damselflies were copulating. One couple, locked in coitus, settled on the deck of my kayak. The male’s abdomen looped up like an inchworm in midstep. After several minutes, they loped off awkwardly across the lake to another stem, still clamped onto each other. Water beetles spun across the surface of the water, leaving intersecting wakes behind them. Spatterdock (Nuphar variegata) was blooming. Potamogeton gramineus fruits were floating just below the surface of the lake. A loon called.
The island shoreline slumps down toward the lake, forming a bench at the waterline. This interface between lake and land is a narrow wetland that I presume is fed by rainwater from above, by waves lapping over it in storms, and by the high water table of the lake soaking up from beneath. Tussock sedge (Carex stricta) rhizomes weave a loose sod in this zone. This same community recurs on many of the lakes, often with tussock sedge. At this site, the C. stricta become increasingly diffuse as they move upslope. As they move into deeper water, they form stout, taller hummocks that rise out of the water. Here they begin to look like the tussock sedges I know from sedge meadows and wet prairies in southern Wisconsin and Northern Illinois. Swamp candles (Lysimachia terrestris) were flowering alongside the sedges. Sagittaria colonies flowered in the shallow water, interspersed with bur-reed (Sparganium) in various states of flower and fruit.
I dropped a paddle into the muck to stabilize my boat for a photograph, triggering an eruption of tiny bubbles. These are the exhalations of the soil, roots and bacteria breathing. Red oak leaves were decomposing in the muck. Perhaps some will win the lottery, become compressed and fossilize, leaving a scarce handful of leaves for botanists 10 million years hence. Perhaps they will help inform future humans or our daughter species about what this place looked like at the dawn of the Anthropocene, as temperatures were rising at a rate last hit about 56 million years earlier.
Rafts of Myriophyllum tenellum floated along the edge of the lake. This is the only North American milfoil to produce scales in lieu of full leaves. Strip all the leaves from most Myriophyllum species, dry them and weigh them separated from the rest of the shoot, and you’ll find the leaves make up 50% to 70% of the entire shoot mass. Do this same thing for M. tenellum, and the leaves will only make up 6% of the total shoot mass. This is a plant that, like spike-rushes and cacti, has pulled the photosynthesis function from its leaves and relegated it to its stems. Without a job to do, the leaves degenerated over evolutionary time, like the eyes of cave-dwelling fish and other troglodytes. The mats of M. tenellum on this lake and some of the others we have visited tear loose and float off in sheets several feet long. They break loose so readily that I wonder whether this is a selected part of their life history.
Gelatinous strands of eggs were wrapped like sodden yard around submerged woody stems and the Potamogeton. In 2022, Susan Knight, a long-time researcher at Trout Lake Station, incubated some eggs we brought her that looked just like these. Caddisflies emerged. A few aquatic smartweed (Persicaria amphibia) inflorescences hovered above the lake, floating leaves arrayed all around them. Paired white bristles jutted from the upper surfaces of several of the smartweed leaves, connected to erect, cream-colored cocoons or eggs on the undersides. Packed around those were translucent eggs or cocoons, flat like candies in a box. How many lives transpire on the undersides of these leaves?
Rachel and I looked around, went our own ways at times and met up intermittently, talked, shared what we were finding, took photos and notes. Our visit to the lake ended as the sun was about to dip below the trees. Big Muskellunge Lake is a universe, increasingly complex as we focus in from aerial photos and the gazetteer to what we can see through a hand lens. There are coves within coves, peninsulas of a few centimeters cantilevered off the tip of an island. Yet it is only one of countless lakes in this landscape.
Spatterdock. Rachel Davis. Acrylic on wood panel, 16" x 20".
The range and life history of Pectinatella magnifica come from the Bryozoans section of the USGS Nonindigenous Aquatic Species site (https://nas.er.usgs.gov/taxgroup/Bryozoans/, accessed 2022-07-23). ↩︎
These dates come from Magallon et al.’s (2015) study of divergence time in Angiosperms, and it underestimates the real amount of time that angiosperms have been angiosperms. 139 Ma is the estimated crown age, the age of the last ancestor that all angiosperms share, from water lilies and Amborella to oaks and peanuts and mints and sunflowers. The stem age—the age of the long lineage of organisms after the split between known angiosperms and known gymnosperms, is 325 Ma. The crown represents Darwin’s “abominable mystery,” the sudden eruption of angiosperm diversity within Cretaceous sediments. Magallón S, Gómez-Acevedo S, Sánchez-Reyes LL, Hernández-Hernández T. 2015. A metacalibrated time-tree documents the early rise of flowering plant phylogenetic diversity. New Phytologist 207: 437–453. ↩︎
Aiken SG. 1981. A Conspectus of Myriophyllum (Haloragaceae) in North America. Brittonia 33: 57–69. ↩︎
Gerber DT, Les DH. 1994. Comparison of leaf morphology among submersed species of Myriophyllum (Haloragaceae) from different habitats and geographical distributions. American Journal of Botany 81: 973–979. ↩︎
The irreducible complexity of shorelines is not my own idea. It is a concept sometimes referred to as the shoreline paradox, which in brief is the problem that there is no obvious way to define the length of a shoreline, or the perimeter of a landmass. If you limit your resolution to 1-km measuring sticks, you will get one measure; if you limit your resolution to 1-m measuring sticks, you’ll get another; and you’ll get others with 1 cm, 1 mm, 1 μm, 1 nm… you get the idea. At some point, you’ll be measuring gaps between atoms, and then what do you do? ↩︎