You're Looking Mighty FINE with a "mudstache".

Hjustrom Diagram: http://www.columbia.edu/~vjd1/streams_basic.htm

Hi, Brooke here!

While we are snorkeling in the rivers we often grow a “mudstache” throughout the search. These fashionable features are due to the sediment flowing through the river. The interaction between the velocity of water and the sediment flowing in it is an important one! The energy (determined by the velocity) of the river, determines how much sediment is entrained and suspended - with more sediment suspended, the greater the “mudstaches” we get.

There are two important diagrams that show the relationship between sediment size and energy of the river system.

One is The Hjulström Diagram below shows the relationship of sediment diameter versus water velocity - showing what speed a particle is in transport, being eroded and deposited.   

Another is Shield's diagram. Put simply, this diagram shows at what shear stress is particle is likely to be entrained (or move along the bed or in suspension).

Sheilds Diagram http://www4.uwsp.edu/geo/faculty/lemke/geomorphology/lectures/03_stream_sediment.html

There are three categories of sediment transport; the wash load, suspended load and bedload.

The wash load of a river is the sediment/debris in the river that is carried by the water near the surface. Usually it will not ever deposit.

The suspended load is the sediment that settles very slow, so slow that it also may never touch the bed of the river. It is upheld by turbulence - and is what causes us to get our great five o’clock shadows.

The bedload of a river is the sediment that is transported along the bed. This transport occurs through the saltation, rolling and sliding of the sediment. Saltation is jumping along of a particle along the bed - rolling and sliding are pretty intuitive.

Saltation image http://www.asu.edu/courses/gph111/Fluvial/LarsonFluvialOutline.html

Unfortunately we do not have any images of us with our fancy-staches, but instead is here a picture of Maya as a burrito! We call this a burrito because we wrap ourselves up in a tarp to keep the car somewhat dry when driving from site to site!

I'm Pretty "Sueur" There Are No Mussels Here

Since Molly and Brooke conquered the Chippewa early last week, it was my and Maya's turn to join Mark and head to the Le Sueur river to aggregate more mussels for our glycogen analysis. We got up bright and early Friday morning and drove out into the cornfields.

The river that greeted us was noticeably different than the rivers we've seen so far. The current was strong, and there were deep holes you wouldn't want to step into with a weight belt on. There were downed trees everywhere; at one site, they had created a dam that was ~30 meters wide and ~35 meters long! 

In addition, there was so much suspended sediment that there was no chance of spotting anything farther than three inches away from your face! This meant we were forced to feel around for mussels, but unfortunately we caught many more mussel-sized rocks. We were only able to aggregate enough heelsplitters and pocketbooks at one site instead of three.

One of our data sheets. As you can see, we did not find any live mussels at this site (although we did see a softshell turtle!!)

15 years ago, the Minnesota DNR found plenty of mussels at these sites. Where, then, have they gone, and why? Maya and I are really interested in thinking about this question and looking at whether land use changes could be a factor here. 

Because of the difficulty in finding enough mussels, and heelsplitters in particular, our team has decided to change one of our target species from the White heelsplitter (Lasmigona complanata) to the more common Three-ridge (Amblema plicata). Hopefully this will make it easier to complete our research!

Mussels and Fishies: An Underwater Romance

When we’re looking for live mussels in the riverbeds, we often find the weathered shells of deceased mussels. Opening the valves, a slurry of sediment and debris obscures your vision for a moment.  Sometimes, though, we discover that these calcium carbonate skeletons have been claimed--by fish! It turns out that these shells make the perfect nesting site for fish (like darters) to lay their eggs.  

Last week, we visited the Sleepy Eye Creek, and were surprised to find lots and lots of shells nestled among the cobbles and boulders. Many more than usual were filled with little gelatinous-looking beads. After taking some pictures, we were sure to return the shells to the water as to not dry them out too much.

A white heelsplitter shell from the Sleepy Eye Creek with fish eggs.

While the fish clearly utilize the mussel shells to reproduce, the relationship actually goes both ways. Mussels (of the living variety) often need fish to reproduce. Male mussels release sperm into the open water, and female mussels will produce eggs and hold them in their gills until sperm reaches them. Since mussels don't exactly have the means to move about far distances, some mussels use a special part of their mantle to entice fish to come try and take a nibble. Others release little packets, resembling food to the fish. Either way, instead of a meal, the fish are surprised with a mouthful of glochidia larvae, which attach to the fish's gills and hang out until they become juveniles. When they're ready, the juvenile mussels detach, having caught a ride to a new home!

Life cycle of mussels. 

http://molluskconservation.org/MUSSELS/Reproduction.html

What the Glycogen: Chippewa Edition

Glycogen

As we've mentioned, it's been a wet summer. However, whether the weather wants to cooperate or not, we need to prepare each site by grouping and aggregating 10-15 specimens of our target mussel species (the White Heelsplitter and the Plain Pocketbook) for glycogen analysis. 

The glycogen analysis is basically a "how happy/stressed is this mussel?" analysis. While humans store fat in their bodies, mussels store glycogen. Thus, the more glycogen present, the happier and less stressed the mussel is. 

Chippewa River Aggregation Location

The analysis must be done to the mussels in the same time period to get comparable data, so whenever we visit a site, we place our mussel collections in specific locations marked by GPS coordinates, where we will hopefully find them once again. 

Chippewa River Sites

This week, Mark, Brooke and I visited the Chippewa River near Benson, MN. Going in, we had little hope of finding enough mussels for aggregation. Water levels were high, and we often wore two weight belts, and even used small boulders as personal anchors to stay underwater and fight the current! Also, because of the murky water, we had to rely on our sense of touch rather than sight. 

Chippewa River Site

But all our hard work paid off: we were able to find and aggregate enough mussels of both species for 3 full sites! We even found a nice amount of the sneaky White Heelsplitters, which were quite elusive in our Snake and Cottonwood sites.

Mussels buried semi-deep in Snake River substrate

Many species in the Chippewa, especially the Three Ridge and the Plain Pocketbook, were of monstrous size and heavily buried. I don't blame them: either burrow into the substrate or get carried away by the fast current. I think I'll try that next time!

Photos Credits:
Jess Kozarek, picture 3

River Watch!

Molly here!

We’ve definitely begun to settle into a routine these days, but every site is different. We've had the chance to see some pretty amazing (and sometimes downright creepy) wildlife above and below the water. This list includes but is not limited to:

-crayfish

-fish

-poison ivy

-muskrat

-bald eagles

-huge, water-hopping spiders (like I said, creepy)

Dragonfly on Snake River

Story time: As we were working in the Snake, Brooke set her equipment down on a branch sticking out of the water mid-channel. It just so happens that the largest spiders I’ve ever seen liked Brooke’s equipment a lot. When we grabbed the weight belt flinging the spiders away, it was a moment filled with pure adrenaline and yelling, and then shock as we watched the spiders jump off the branch and hop along the water to the shore. I’m pretty sure our mouths were wide open.

You can imagine, though, what years of human habitation near rivers can do. There are also non-living things in rivers, such as:

-broken bottles

-fishing lines

-farming equipment

-bridge materials

-bicycles

Non-natural things can be a little dangerous. We typically wear gloves, and try to slowly move our hands along the river bed as we search for mussels so as not to hurt ourselves. 

All in all, though, what can I say? We are constantly entertained by the job, and I'm glad to be a part of this unique experience!

Snake River Site

Are Two Weight Belts Enough?

Taking Sediment samples in the Snake River at high flow.  Photo courtesy of Macalester Promotional Material.

This past week we got the opportunity to revisit a previous field site - except during a much higher flow! The first time we went out  the river was flowing around 250 cubic feet per second (cfs, or the volume of water moving through the channel), when we visited this week, it was about 550cfs - this made working in the field quite different. There was a noticeable change in the appearance of the river bed - less fine grained sediment and fewer live mussels!

Taking sediment samples during normal flow! Photo courtesy of Jess Kozarek.

When we collect sediment samples, someone sinks to the bottom and scoops up sediment with a cup - this past time the water movement was much faster - pushing the scooper downstream very quickly. I personally like to use Molly’s legs as a anchor!

As water flux increases, the velocity increases. This higher energy allows for more sediment to move along the bed, or become suspended in the water. This fact was very present at this site in the Snake River. When snorkeling, the visibility had decreased greatly from the last time we were at the site - making it harder to find the mussels.

Yay, cookies! Photo courtesy of Macalester Promotional material.

The mussels we did find were few, and often just shells. Where did all the mussels go that we had found there less than a week before? Had the burrowed deeper? Or traveled with the current downstream? Or could we just not see them?

The hard work was all worth it for some Dan’s homemade cookies!

cfs data found at: http://waterdata.usgs.gov/nwis/uv?cb_00065=on&cb_00060=on&format=gif_default&site_no=05338500&period=&begin_date=2015-07-01&end_date=2015-07-08

Pocketbook, Pigtoe, or Spike?

For the first week or so (and a little bit even now), looking at the big pile of our collected mussels on the shore was completely overwhelming. How on earth was I supposed to know whether the mussel I was holding was a Round or a Wabash pigtoe? Which one was A. Lig? And are pocketbooks and L. card the same thing? Every scientific name sounded the same, and even worse, all the mussels looked the same. They looked like roundish, flatish rocks.

But! There is hope! Only a couple of weeks in and we can all identify way more species than I thought possible. Here is a quick list of the most common species we are encountering in our fieldwork:

Spike (Elliptio dilatata): This mussel is easy to identify because of its elongated shape, much more exaggerated than most mussels.

Elliptio dilatata

Ligumia recta: Looks extremely similar to E. dil, except that the raised line on each shell starting from the hinge of the mussel, called the posterior ridge, ends on the side of the shell instead of the bottom (in other words, it ends medially instead of ventrally).

Three-ridge (Amblema plicata): By far the easiest mussel to identify-- just look for those ridges! Sometimes there are more than three, however.

Wabash pigtoe (Fusconaia flava): My favorite, it has a wonky shape but is overall much more round than mussels that have a slightly elongated shape. It also has a bright orange foot!

Fusconaia flava

Pocketbook (Lampsilis cardium): Very fat. Very, very fat. So fat. Definitely the most curious- they are the first to open their shells to explore their new surroundings when we gather on the riverbank to sort our catch.

Lampsilis cardium (center) and Amblema plicata (right)

Pink heelsplitter (Potamilus alatus): Named the heelsplitter because of its shark fin-like appendage on its top, which you would definitely not want to step on! They’re also usually much larger than other mussels.

Potamilus alatus

White heelsplitter (Lasmigona complanata): Looks exactly like the pink version, except that its sides are much flatter and not inflated. It can be hard to distinguish between the two. Both heelsplitters can be a bit of a jokester and squirt you with water when you hold them up in the air.

Mucket (Actinonaias ligamentina): If it has no real distinguishing characteristics and just kinda looks like a mussel, I would bet you’re holding a good old mucket.

Leptodea fragilis: Just like the mucket, but really light. Extremely light. Suspiciously light.

Photo credit:

http://www.museum.state.il.us/ismdepts/zoology/mussels/gallery.html?RollID=mussel_01&FrameID=potamilus_alatus677337a
http://wwx.inhs.illinois.edu/collections/mollusk/publications/guide/index/46
http://www.snipview.com/q/Elliptio
Macalester promotional material