Urban Stream Syndrome
This week I traveled to central Virginia to electrofish an urban stream. Ordinarily, I wouldn’t be so excited to work all day in a 110° heat index to catch nearly 1,000 minnows, but this stream holds a special place for me.
Ten years ago I didn’t know fisheries biology was a thing. And, if you had told me I could (and would) make a career studying fish, I probably would have rolled my eyes and asked if you had too much to drink. That all changed in 2006 when I started my freshman year at Randolph-Macon College and was placed in a class called “Repairing Nature.” The course description emphasized a year-long class centered on understanding the ecological, sociological, and economical requirements for restoring an urban stream.
“Great,” I thought, “I’m going to plant some trees.”
Boy was I wrong. On the first day of class we took a trip about a mile away to Mechumps Creek, a small stream that flows through my hometown of Ashland, Virginia. Looking at the stream, I didn’t understand the problem. Sure, there was some trash that needed removing, but other than that I didn’t see what needed to be restored.
The answer was everything. And, once I realized that answer, my career path was set in stone.
Mechumps Creek suffered from “urban stream syndrome.” When it rains in a forested watershed, water slowly seeps into the ground and slowly reaches streams. But, in urban settings, parking lots, roadways, buildings, and other impervious surfaces prevent water from reaching the ground. The water has to go somewhere, and the traditional solution is to channel all of it into storm sewers which then deliver water directly to streams.
Typical stream profile for a natural (top) and urban (bottom) stream. In an natural stream, erosion is minimized because, after storms, stream flow slowly increases, tops the banks, and spills over onto the floodplain. In an urban stream, so much water is delivered to the stream so quickly that the stream bottom erodes. The stream continues to erode downward and eventually water can no longer reach the floodplain.
Think about that for a second. During a heavy storm (or a hurricane, as central Virginia often gets) all of the rain water from the entire watershed is being delivered directly to the stream. It’s not only tons of water, but it’s also polluted by anything that was on top of the road (often automobile oils and fuel and trash).
This change in the timing and magnitude of water reaching streams has devastating effects to the shape of the stream channel. In natural streams, stream flow slowly increases, reaches the top of the channel, and then floods the surrounding land. This “spill over” onto the floodplain, decreases stream flow velocity and minimizes stream erosion.
However, when too much water is delivered too fast, stream flows increase so rapidly that they erode the stream bottom. After several years the stream continues to cut deeper and deeper, eventually leaving really high banks. It’s then a positive feedback loop where the stream can’t “spill over” and can only continue eroding deeper (see the above figure for a visual of this effect). Most species of fish and aquatic bugs cannot survive these high flows and sedimentation, and so species diversity drops dramatically.
To this day I can’t really tell you why I find urban streams so interesting. But, standing on the banks of Mechumps Creek and hearing that story, I immediately volunteered to spend nearly my entire fall semester with a small group of students measuring how eroded the banks were in Mechumps Creek (because of this work I was asked to join the trout lab, and here I am today….). Our measurements went to an engineering firm, who drew up blueprints for the stream restoration.
The goal of stream restoration is to design a channel that will not erode during storms. This is accomplished by literally relocating the channel so that the stream can “spill over” onto a floodplain (hard when the floodplain is where fast food restaurants are located) and placing hard structures throughout that lock the stream in place. All of this is expensive, and it took until 2010 to piece together enough grant money to start restoration in Mechumps Creek.
Photos of Mechumps Creek before (left) during (center) and after( right) restoration.
One reason the grant application for the restoration was successful was that my professor at Randolph-Macon promised to monitor fish populations and habitat for 10 years to determine if restoration was successful. So, every July, him and I return to Mechumps Creek. It’s a humbling experience to think that my career started there, by accident, 10 years ago. It’s also very interesting to see species that have returned to the stream. While we always caught creek chubs, bluehead chubs, tessellated darters, and bluegill, over the years we have slowly seen the reappearance of mud sunfish, American eels, mudminnows, pirate perch, and this year grass pickerel.
There’s another section of Mechumps Creek that is currently proposed for restoration, so I may have more warmwater electrofishing in my future.
Fish Phlebotomy 101
he name of the game is the same: It’s hot, dry, and the fish are disappearing from predation. On Monday there was a panic when we showed up to track and there were several new tags gone. From here, the short-term plans I was brewing for the study went up in a gigantic ball of fire, and the lighter fuel looked something like this:
11:30am: A thunderstorm rolls through the area. I find spotty cell service to check the radar and I email my advisor a quick update (mostly to occupy my boredom). After an hour the storm clears, I’ve heard nothing from my advisor, so I carry on with my day none the wiser.
8:00 pm: I get back to the house after tracking and check email before going to bed. I find it odd that my email is taking a while to load, until I realize there are 67 new messages. I scroll down and see the names of my advisor and other collaborators popping up a few more times than they should. This can’t be good.
9:00 pm: After talking to my advisor, we decide to start sampling ASAP. This is why you don’t check email before bed.
1:00 am: Sampling crew contacted, weekend trip to Virginia pushed back, sampling supplies inventoried, mini panic attack that I just moved up a major aspect of my project by over a month.
So, why the sudden change? I’ve mentioned before that we take a gill and blood sample from every fish that we tag. One of the reasons we do this so that we can determine how fish are responding to temperature stress at a molecular level. In the spring we collected tissue from fish that were loving life at stream temperatures near 50°F. This is the equivalent to a relaxing spa day for us, and so it serves as a baseline for what tissues look like when fish are not stressed.
Fast forward and now trout are trapped in water that is 15° warmer and some of the molecular markers have changed in response to the heat stress. But, just like when you come inside to air conditioning after a hot day in the sun, as soon as the water cools down fish will return to baseline. Not knowing how long we have before the heat streak snaps, and because we have already lost so many tagged fish, we had to pull the trigger and push the sampling up.
We are still trying to decide exactly what we will look for in the tissue samples, but one focus right now is heat shock proteins, or HSPs. HSPs are produced by cells in response to heat stress to prevent cell death and are easily detected in the gills of fish. We know we should find a difference in HSPs from spring to summer to fall, but that’s not all that exciting (it will basically just tell us that HSPs are more prevalent when it’s hot).
But, more interestingly, we are curious whether some populations show an adaptation to chronic heat stress. While HSPs are necessary to prevent cell death, they are produced at the cost of reduced growth and reproduction. So, fish can’t just produce a bunch of HSPs because then they won’t have any energy to survive. We are curious whether populations that are exposed to more heat are more efficient producers of HSPs, are acclimated to heat and don’t produce as many HSPs, or if heat is stress that can’t be overcome.
We lucked out and accidently picked one site that is not only warmer than the others, but also more variable in temperature. So, we are curious to see how HSP production differs in that stream in comparison to the others. Regardless of the result, this is one of the first studies of HSPs in natural trout populations, so the results will help us forecast trout response to future warming or at least design follow-up studies to address the question.
For now, we have sampled a little less than half of the study sites. When we sample we are only targeting fish that are currently tagged, so in theory it should be easy. Wrong. These fish are incredible at finding little crevices to hide in, and despite knowing a tag is within 5 feet of you we are still averaging about 30 minutes or more per tag. The dilemma is deciding when to keep trying to recover the tag because you think it’s a hiding fish vs. when to give up because it’s a dropped tag in a deep hole. So, we’ve been throwing rocks, wanding heavy magnets to pick up tags, and pumping voltage (special thanks to Steve and Linda Szoke, who volunteered the first day and taught me a little patience in this task!). Slowly but surely, we’ll get there.
Loyalsock sampling resumes next week, but for now I’m in Virginia for a few days to catch up on non-field life and to help sample an urban stream I’ve been working on since 2006. Why do I volunteer to sample a tiny stream in July when it’s at least 100°F and the bulk of the work is counting juvenile minnows? You’ll have to stay hooked to find out….
When I’m doing monotonous field work I often purposefully get a song stuck in my head to help pass the time. This week Johnny Cash’s “Ring of Fire” was a perfect fit for the conditions in Loyalsock. Streams continue to heat up and dry out, and the weather forecast shows no end in sight. Fish movement has largely stalled and tags are now found almost exclusively in pools where there is some refuge from predation and somewhat lower water temperatures. Last week I wrote about how fortunate we were for such severe conditions, but I’ve since changed my tune and have had to completely overhaul the upcoming sampling schedule to avoiding stressing during tagging. But, if there’s one thing I know for sure, it’s that field work never continues as planned.
Now that we’ve hit a bit of a lull in the telemetry updates I can introduce another aspect of my project. From movement to genetics, we spend a lot of time collecting data on individual fish. Why? Well, we are interested in what causes individuals to behave differently and while it could be genetic differences it could also be due to differences in personality.
Yes, I just said that fish have personalities. And, much like humans, there is a bit of a ‘nature vs. nurture’ debate about what causes personality to develop. We know that both genes and environment are involved, but we’re curious as to whether certain genes tend to produce certain personalities. More importantly, we want to know if certain personalities tend to move more than others.
In humans, the five major personality traits, also known as the “Big Five” by psychologists, are openness, conscientiousness, extraversion, agreeableness, and neuroticism. While we can’t exactly measure a fish’s neuroticism, there are reliable test for fish that measure such things as aggression, exploratory tendency, and sociability. The most tested personality trait in fish is boldness, and it’s the trait we are attempting to relate to fish movement and genetics.
In addition to being comparable among many other studies, boldness is also relatively easy to measure. You simply place a fish in a tank, allow it a few minutes to calm down, and then record the amount of time the fish spends moving around and in the center. The idea is that when a fish is scared it will try to seek shelter by the sides of the tank. The less a fish is scared in this new environment the more it spends moving around and the bolder it is.
Last year I assessed boldness for nearly 400 fish across 16 sites in Loyalsock. This is one of the first field studies of personality, and by far the largest sample size (the next largest is probably well under 100 individuals). This year we will assess personality for tagged fish to look at how our personality assessments relate to genetic and telemetry data. Ultimately we’d like to find the driver for personality, and provide some information about how and why personality should be considered in conservation plans. For example, stocking only fish that are bold and move really far may not be advantageous when trying to re-establish a population or when surrounding habitat is not suitable for trout.
There’s also other reasons to consider personality in conservation (for example, some personalities are smarter than others), but you’ll have to stay hooked for that.
Behavior was filmed with an overhead camera and I'm in the process of quantifying boldness. I use special software to track the fish around the tank so I can determine how much time it spends moving around the tank (which is indicative of boldness) vs. on the sitting on the side (a sign of shyness).
How Low Can They Go?
It takes years to coordinate, design, and execute a telemetry study. When the wheels started spinning on this project I wasn’t even a graduate student at Penn State. So, needless to say, there is no way to plan around unpredictable things like weather. Coming off a relatively mild summer last year, all we could do was cross our fingers and hope that this summer would have the hot and dry conditions that are predicted to become more common in future years.
In this game of field work Russian roulette, we won. Loyalsock Creek is barely trickling. The pools that were once too deep to wade through barely touch my knees. Between Tuesday and Thursday we saw stream temperature rise as much as 7°F. The ground is now so dry that stream flows are still decreasing even after heavy overnight rains.
I’m not sure how much lower the streams can go, but we’ll soon find out. The forecast predicts even hotter and dryer weather for the next week. For the fish, this means several things. First, rising stream temperatures are going to create stressful conditions that put fish at a high risk of mortality. So, if you’re reading this and considering going fishing, it may be better to hold off until stream temperatures decrease a bit (which may be awhile). It’s a well-known fact that angling mortality dramatically increases at high temperatures because fish have a harder time recovering from hooking stress.
Second, fish are becoming sitting ducks for predators. With lower flows pools are shallower and many undercut banks and rock crevices that are good for hiding are no longer under water. Further, fish have a higher metabolism at higher temperatures. This means they are willing to put themselves in riskier situations and spend more time trying to forage at the risk of being nabbed by a bird or opossum. The last two weeks we’ve found many more tags in banks or dangling from trees. Unfortunately (but also interestingly) many of the predated fish have histories as being some of the more mobile fish in the study. This observation fits in with a lot of ecological theories of animal behavior, but it’s too soon to tell if we have enough data to definitively say that the “mover” fish are more prone to predation.
This past week we also surpassed 1000 detections, biopsy samples were delivered to the USGS Leetown Science Center in WV to start analysis, and plans are inching forward for August tagging. I continued to be overwhelmed by the support and interest that everyone has shown for this project. This week we started a conversation with a local news station about doing a segment about my project. So, stay tuned, literally, as The Troutlook may wind up on a television near you.
One last thing, on Tuesday I electrofished some trout to practice new suture techniques and accidentally caught a fish that was tagged in May. As you can see from the photos below, the fish was looking great with a completely healed incision and no infection from the antenna exit site.
If you're paying attention, you'll notice that most of my posts talk about what WE did during the previous week. Who is this we I refer to? No, I'm not talking about my research collaborators (their time will come soon), but my summer technician, Savannah. Savannah has shared just about every field hour with me and deserves a little spotlight for all her hard work. So, take it away Savannah..
My name is Savannah Rhoads and this summer I am working as Shannon's technician in Loyalsock, PA. I assisted with the initial electrofishing and GPS tagging, and I will continue to help with tracking the movement of tagged Brook Trout until August. I am currently a junior at Susquehanna University, majoring in Ecology and minoring in Psychology. I would prefer to find a career focusing on animal behavior in captivity versus in nature, or possibly with a conservation agency. If I am unable to find a job in my field, I plan on pursuing my education at a graduate level, possibly focusing more on Marine Studies. So far this summer I enjoyed helping with the minor surgeries performed on Brook Trout to insert the telemetry trackers. I learned how to take a blood, gill, and fin sample as well as how to make the small incision for the tracker, and how to properly suture the fish back up, which I found to be much harder than it looks! I'm looking forward to seeing exactly how far the fish travel this summer, and to determine the effects of stressful situations (low flows, warm temperatures, etc.). Also I’m excited to see how summer and fall movement differs. Overall I'm really enjoying this summer, and I'm glad to be a part of this project!
What about friday?
Another week, another 200 detections. And, better yet, few dropped tags. We found three tags that seemed to be the victim of predation (most likely of the human variety this time), which was a huge relief after the struggles we had with dropped tags the last two weeks. Leaving Loyalsock Thursday night I was breathing a little easier thinking about the fate of this project.
But, wait…Thursday? What about Friday?
No, I haven’t forgotten that the work week is five days. But, by Thursday deep soreness sets into every major muscle group (who knew fingers could get sore?) and we are toting around a significant amount of data. I personally get a little nervous when a week’s worth of hard-earned data are stored on a single device that is prone to randomly turning off and gets temperamental when surrounded by too much nature (rain, for example, is an instant death sentence to the GPS).
So, it’s back to State College every Thursday night and Fridays are my day to play catch-up in the office. This “behind the scenes” work isn’t nearly as glamorous as the field. It starts well before sunrise (at least we have to wait until daylight to track!) with several hours of me pleading to the GPS to connect to the computer (I swear it plays games with me). Once I win that war, it takes a while to download the data, so I pass time repairing equipment, ordering supplies (August tagging begins soon!), and looking over the hundreds of emails I turned my eye away from during the week.
Sometime around mid-afternoon I finally circle back around to the data which appear as little non-descript dots on a map. Anti-climactic is an understatement. But adjust a few settings, work a little magic, look back through field notes, (make another pot of coffee), and suddenly there’s a twinge of excitement.
Like when you see that one 6-inch fish has moved over 7 football fields away. That may not seem like too far, but it’s over 4200x it’s body length.
Or you notice that some fish are moving between streams
And that there are some fish that consistently occupy habitats that are 2-3 degrees colder than other fish.
At that time you close the file, pack it in, and leave because if you look too closely you’ll spoil any chance of enjoying a little bit of the holiday weekend.
Happy and safe July 4th from The Troutlook! Don’t forget to look at the research tab for new information about the current project.