More Than Just a Shell

I go down to the edge of the sea.

How everything shines in the morning light!

The cusp of the whelk,

the broken cupboard of the clam,

the opened, blue mussels,

moon snails, pale pink and barnacle scarred—

and nothing at all whole or shut, but tattered, split,

dropped by the gulls onto the gray rocks and all the moisture gone.

It’s like a schoolhouse

of little words,

thousands of words.

First you figure out what each one means by itself,

the jingle, the periwinkle, the scallop

       full of moonlight.

Then you begin, slowly, to read the whole story.

Breakage by Mary Oliver

Treasures
two shells i found

Snow crunched under the weight of me. My boots left tracks down to the river where I saw a rock that looked like a shell, wait, was that a shell? The only shells I’d ever seen in Minnesota were those tiny snail shells at the shores of lakes or the ones people bring back from vacations to Florida. It was cracked in half—and another as well, and, what?! another and another—four halves. All brown and muddy, hiding under a sheet of ice that rose up over the shore of the river. They were buried in the glowing light under the frozen cover. I flipped them over, and they were pearly white and empty, like they had been preserved in that ice forever and then melted out, like mermaid treasures washed up all the way from the ocean. There was a small, misshapen pearl in one. What luck!

I carefully carried them inside and looked them up, determining that these abandoned shells were, in fact, Freshwater Pearl Mussels. Depending on the species, they were considered either endangered or low risk. Through species identification books I later found their closest match—Villosa villosa—not listed as endangered. But who knew there were so many species of mussels—let alone any that lived in Minnesota? North America is home to more than 300 species—more than any other continent in the world! For some reason this fact escaped my knowledge of nature for twenty years, and yet they’ve always existed in that time. How much do I have yet to discover, and how much does the whole world have yet to discover? So little is known.

botticelli-birth-venus
birth of venus by botticelli (uffizi)

Venus came from a shell like this. Prehistoric people used the shells and pearls of mussels to decorate themselves and their graves. But, according to Wendell R. Haag, up until thirty years ago, “we knew virtually nothing about the basic ecology of freshwater mussels. With a few notable exceptions, mussel research… usually involved collecting mussels, getting rid of the ‘meat’ as quickly as possible, and whisking the shells away to museum drawers” (Haag xii). Scientists who studied mussels then considered themselves “conchologists,” or studiers of shells. Mussels were seen more as living rocks, which is understandable (at first glance I thought they were rocks, too). But under the water, mussels live and even sometimes move… Only recently has the true story of these animals begun to be told. This is a whole new field of study.

We need to understand the ecology of freshwater mussels. They are a keystone species, research suggests. They filter the bodies of water that they live in, and cycle nutrients. They provide physical habitats and food for other animals, and might also provide calcium to calcium-poor waters (Haag 43). Up until fifty or so years ago, scientists called freshwater mussels naiads. “In Greek mythology, Naiads were nymphs who inhabited and gave life to fresh waters. A Naiad was intimately connected to a specific body of water, and her existence depended on it; if a stream dried up, its Naiad expired” (3). The name naiad can no longer be used for mussels, however, because the name has already been taken by some other aquatic larvae. Nevertheless, mussels still make a name for themselves. Many places in North America are named after mussels, meaning they must have been very abundant in the past. Think Clam Lake, Pearl Lake, Shell Creek, and others—all place-names in Minnesota and other states as well.

91708 two dot musselshell see 5561 single283
musselshell river, MT (montana pictures)

Shells, like tree rings, record growth and other life events. It is a wonder that any mussels survive to tell their stories at all, though, for whether or not they live to maturity is dependent upon many factors. Males release sperm which are inhaled by females. The fertilized eggs develop in the female’s gills. Environmental cues trigger the release of larvae, which at that time look like mini mussels, but their shells are kept open until they clamp down on a fish’s gills (Skinner 4). Although freshwater mussels are free living for most of their lives, in nearly all species, larval development “is dependent on a period of a few weeks during which larvae are parasites on fish” (Haag 37). Most don’t find a fish and are swept away. Those who make it live in the gills until they drop off and hopefully find a sandy place to land. This is when they burrow, and live for anywhere from 5 to 50 years, depending on the species. Some legends say that they can live for over a hundred years.

Aristotle thought mussels “arose spontaneously from mud or sand.” Wendell R. Haag notes that “this would be remarkable indeed, but as always, the truth is even more interesting” (Haag 37). Even though “mussels live most of their lives burrowed at the bottom of a stream or lake,” some species are more sedentary than others (31). While mussels aren’t really able to swim up, they do sometimes move horizontally using their “foot.” Only a small percentage of mussels across many individuals and species move enough to be noticed, but those few are the adventurers, much like some humans are adventurers. Some may move because the water is too shallow, but still very little is known about mussel movement. Many parts of mussel’s lives are still a mystery to the scientific world.

Screen Shot 2017-04-10 at 8.11.49 PM
the secret lives of mussels (sue scott via skinner)

Though we’re only just getting to know these animals, like many animals right now, in our time of the sixth great extinction, many species of these intriguing creatures are quickly disappearing in many areas. It’s not the first time, however, that mussels have been threatened by human action. “Despite the great importance attached to freshwater pearls by Native Americans and early European explorers, large-scale pearl harvest in historical times began relatively late but abruptly” (Haag 295). In 1857, a pearl was found by a carpenter in New Jersey and was bought by Tiffany and Co., where it was ultimately sold to the Empress Eugenie of France. This sparked the “first great pearl excitement.” Everyone wanted in on this new pearl craze. Pearls were also later turned into buttons, an industry that further destroyed mussel populations. Because of buttons, “many [mussel] beds were considered commercially exhausted by 1899” (306). Though the button industry didn’t do as well during the Great Depression and through the dawn of plastic buttons, shells continued to be harvested (309). One good thing that came out of this, however, was the beginning of a realization that humans have a direct impact on mussel populations, and are likewise responsible for saving them.

The next pearl rush was in the nineties, though this time the fad was rounded pearls instead of buttons. On top of over-harvesting, zebra mussels were introduced in 1988, which almost completely killed all native freshwater mussels in the Great Lakes. Populations are only just now recovering again from that time (Haag 314). Mussels used to literally pave the bottoms of North American rivers. Hunting/harvesting, chemical spills, pesticide use, and other forms of habitat destruction have wiped out populations in the last 100 years. Also, “more than 75,000 dams in the United States severely disrupt the continuity of the river landscape and affect to some extent every major watershed in the country” (331). Dams have directly made extinct at least 12 mussel species, who are directly impacted by water flow (332). Even when dams stopped being built so often in the 1980’s, mussel numbers still declined due to isolation and fragmentation. In the last 100 years, we’ve lost 30-40 species forever.

Processed with VSCO with a4 preset
a qualitative sketch of mussel populations according to haag’s research and outlook (this could be completely off)

After all of these losses, the mussel population in the Mississippi River is still currently estimated to be greater than the whole human population of the United States. Even with these numbers, though, we could still lose half of all North American freshwater mussels in the next 100 years. If fragmented species that now exist go extinct, larger numbers of species could disappear as well. (Haag 391). Human help is needed now. Conservation of mussels for use has been happening since the early 1900’s, and since the Endangered Species Act in 1973, they have begun to be protected for their own sakes. Habitat restoration is one way to recover mussel populations (396). The future could look rather bright, thanks to the Clean Water Act and other legislation, though now that order may be reversed again. “Trump said he is ‘paving the way for the elimination’ of the rule” (NPR). Public awareness and efforts to help clean drinking water help the mussels as well as humans. We, as living things on this earth need to work together and help each other. Stories matter now more than ever. The scientific truth needs to be told. More is learned every day in the field of mussel ecology and in countless branches of science everywhere. Here’s to making sure freshwater pearl mussels once again become part of our cultural landscape, because if we care for our environment and have clean water, mussels will live on. And if we care for our environment and have clean water, we, too, will have life.

thanks to:

Haag, Wendell R. North American freshwater mussels: natural history, ecology, and conservation. Cambridge: Cambridge U Press, 2012. Print.

Kennedy, Merrit, and Susan Phillips. “Trump Aims To ‘Eliminate’ Clean Water Rule.” NPR. NPR, 28 Feb. 2017. Web. 10 Apr. 2017.

Skinner A, Young M, & Hastie L (2003). Ecology of the Freshwater Pearl Mussel. Conserving Natura 2000 Rivers Ecology Series No. 2 English Nature, Peterborough.

http://www.uffizi.org/artworks/the-birth-of-venus-by-sandro-botticelli

http://www.montanapictures.net/two_dot_montana_landmarks.htm

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s