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Graduate students do a lot of reading. And, sometimes, you stumble on a research article that is so obvious you wonder why you never thought about it before. For me, one such article was, “Landscapes to Riverscapes: Bridging the Gap between Research and Conservation of Stream Fishes” coauthored by Kurt Fausch and his colleagues in 2002. I first read this article as an undergraduate, and it’s probably been assigned reading in no fewer than five other classes along my academic journey. Every time I read it I think two things. First, “duh”. Second, “why are we (still) ignoring these concepts in our management of fisheries?” The take away message is that fish ecology is often not reflected in our design of research projects and management of fish populations. Seems like a major oversight, right? In everyone’s defense, it’s really difficult, perhaps impossible, to cover all aspects of a species’ ecology when designing a research project. For example, we’re lucky if we can scrape together enough funding to run a project for 2-5 years. But, many fish species live much longer than that and are affected by processes that occur much less frequently (e.g., disease, rare weather events) or over very long time scales (e.g., climate change, evolution). So, we end up with a series of studies with important results, but results that many not be entirely appropriate for the species of interest. For example, a short-term study on the effects of floods on fish populations might conclude that they are catastrophic. But, if you look 10-50 years later, you might find that they are beneficial. Likewise, scientific crews are often small, overworked, and under paid. We can only cover but so much area, and so we decide to sample a few hundred feet, maybe yards, of habitat. Or, we might use aerial maps to visualize entire watersheds. But, with these two approaches we’ve missed the spatial scale that is likely most important. Fish don’t stay put in one pool, or even a small stream segment. And, very often, they don’t move around the entire watershed. The scale that is probably most important, at least for trout, is measured in miles. But, sample crews can’t measure fish and habitat across miles of stream, and we certainly can’t use maps to document the fine-scale habitat features that are found in these stream segments.  A figure from "Landscapes to Riverscapes" illustrating the scale gaps we have in understanding fisheries ecology. Many processes that influence fish life history happen at spatial and temporal scales that we aren't studying and aren't managing.  After years of study, a reasonable assumption would have been that the Arkansas darter stayed in isolated pools. But, that would have been incorrect, as it was found that the darters were able to make long-distance movements to new pools during rare storm events. The scary thing is that our data often lie to us, and we don’t know that we’ve collected information at the wrong temporal or spatial scale needed to answer the research question of interest. We could study the same population of fish for decades and never see movement. But then, suddenly, a slight increase in temperature or a little bit more rain, and you may see long-distance dispersal (this happens in populations of Arkansas darters, which seem to make long-distance movements, but only every 5-10 years after heavy rains). Or, we might study a species only during summer (which is common) and miss seasonal behaviors or changes in habitat use that correspond to different stages in the individual’s life cycle. And, if we do that, we may (and often do) falsely conclude that fish don’t move or make some other inaccurate statement about a species’ ecology. Even more scary, these rare events and small-scale habitat features that we very often miss in our studies are some of the most important for fish populations. It’s the rare, long-distant movements that recolonize streams and connect populations. And, it’s the seasonal use of tiny areas of ground water upwelling or short-term occupancy of unique habitat features that fish use to spawn or survive thermal stress.  Upper sections of Loyalsock Creek are a fisheries biologist's sampling nightmare. Wading through it is like trying to walk on greased bowling balls, and parts of scuba destination. Who knows what's actually in there. Though scientists are starting to realize the inadequacies of our studies (not to say we are fixing them, our hands are often tied), management hasn’t always kept up. For starters, managers’ hands are also tied. They can only work with the information they have and, as I’ve said, the information is often inaccurate or missing. But, sometimes, the protocols in place for protecting fish species need updating to better reflect improved information on species ecology- information that highlights the importance of considering different temporal and spatial scales in management plans.
Take for example Pennsylvania. In Pennsylvania waterways are given a designated use classification based on the aquatic species present. The streams I’m currently researching have different designated uses depending on the exact location, but include “Exceptional Value,” “High Quality Cold Water Fishes,” and “Migratory Fishes,” largely due to the presence of healthy trout populations. But, Loyalsock Creek itself has a designated use for ‘Cold Water Fishes’ indicating the river is used to propagate or maintain cold water species, including trout. What’s the problem? This designation system emphasizes population size, which is a very reasonable approach when considering the data in hand and average conditions. Shanerburg Run is a high quality system because there are far more trout there than in Loyalsock Creek and, unlike Loyalsock Creek where summer temperatures far exceed trout thermal tolerance, Shanerburg Run can support trout all year. Further, evidence of wild trout in Loyalsock Creek has been limited because most sampling occurs in summer (when Loyalsock is too hot) and the system, which is a combination of deep pools, shallow riffles, and large boulders, is test for all fisheries sampling gear. However, as we are learning from our telemetry study (and perhaps the anglers of Loyalsock already knew), Loyalsock Creek may be critical over-wintering habitat for a sub-set of brook trout. They don’t stay there all year, and it’s certainly only a small proportion of fish, but these nomadic individuals may be critical for sustaining brook trout population connectivity. As I talked about in my post last week, connectivity greatly improves population health by increasing genetic diversity and lowering the probability of population extirpation. So, protecting these fish may be disproportionately more important when considering conservation strategies. Given this, are main stem rivers getting enough protection in brook trout watersheds? It’s hard to say. This is one case on one small scale with results that are still unfolding. But, it does highlight the need to think beyond “average” and consider how fish habitat use may change depending on the time and space scale you are considering.
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 Large floods, like the historic 500-year event that hit Loyalsock Creek in 2011, are surprisingly necessary for long-term trout survival. Photo courtesy of PA State Police. There’s been a reoccurring theme in my posts- stream flow is really important. When streams rise too far, trout can wash downstream and die. When there isn’t enough flow, stream temperatures rise, oxygen availability declines, fish become trapped in isolated pools, and, you guessed it, they can die. But, trout aren’t the Goldilocks I may have led you to believe. Headwater streams are some of the harshest environments an animal can live in. They are a complex mosaic of habitats- riffles, runs, pools, glides- all connected by the unpredictable flow of water. Flood stages and drought conditions can be separated by only a few hours. Stream temperature changes quickly with rain and air temperature. Aquatic macroinvertebrates, a trout’s major food source, follow their own schedule, and fish have to sit and wait for a causality to float downstream (and in doing so expose themselves to predators). The only thing predictable about headwater streams is that they are unpredictable. Rivers and large streams are less erratic than headwater creeks, but these larger systems are often too warm for trout and don’t have the right food sources (though, some trout can use these habitats…a story for later). So, for most of the year, trout are basically stuck in these unpredictable headwaters. To survive, trout need to be tough. But, it also takes a team effort. In this case, the “team” I’m talking about is the ecosystem. And on this team, unpredictability isn’t just something that organisms have evolved to survive, but is a necessary player. And, one element of unpredictability needed for survival are what we humans have decided to call “natural disasters.” Take floods, for example. Loyalsock Creek has had its fair share of flooding the last five years. In 2011 there was a 500-year flood (meaning stream flows are predicted to get that high only once every 500 years). And, just last week, parts of Loyalsock were hit hard with floods that washed away bridges and homes. These events are devastating for humans because we’ve decided to build structures alongside streams. But, trout depend on floods for long-term health for several reason: Floods clean streams: Trout hate sediment. It scratches their gills, suffocates their eggs, and decreases overall water quality. It can also be a source for diseases and parasites. Even the healthiest streams receive sediment from erosion of riparian land, and the only way to clear it from the stream is with high-velocity stream flows. In a forested watershed, the average rain event will cause little change in stream flows. Streams flows may increase more in an unforested watershed (because there are fewer trees and plants to absorb rain water), but total stream sediment increases because of more riparian erosion. Really high flows and floods are needed to completely clean the system. These high flows cause fine sediment and small gravel to become suspended in the water column and wash downstream. As sediment is passing by, it scrubs algae off rocks and boulders and uncovers a fresh stream bed. What’s left is cleaner trout habitat with less fine particles. Floods create habitat. If you fish, you know some of the best trout habitat includes submerged logs and large boulders. These features create deep pools and are good hiding spots for trout trying to avoid predators. But, they are extremely heavy. Luckily, water is very powerful. Heavy rains erode banks and cause riparian trees to fall into the stream. But, really heavy floods mobilize trees and boulders from much further away. A large pulse of water can cause a downed tree from the hillslope to enter the stream and become trout habitat. In fact, the lack of fallen trees in watersheds that have been historically logged is a common source of habitat loss in trout populations. Forests less than a century old may appear healthy, but most trees are likely to still be standing and so less wood is available to enter streams during floods.  To the naked eye, Shanerburg Run looks like a healthy trout stream. But, the lack of submerged logs is a sign of a watershed still recovering from historic logging. Floods reconnect populations. On average, trout are good at hunkering down and staying put during high flow events. But, in flood conditions, many fish do get washed downstream. Some likely perish, but survivors find new habitats. This can cause new streams to become colonized or temporarily connect otherwise isolated populations. This is extremely important because connectivity is key to long-term population survival. Populations that are connected have higher genetic diversity, meaning there are more forms of a gene present in the population. This is critical, particularly in highly variable environments like streams, because different genes are better at surviving different forms of stress. Let’s think about a fake example that will bring this point closer to home. A population with low genetic diversity in humans may have, for example, a high proportion of people with blue eyes. If there is a lethal disease that effects only people with blue eyes, then that population would quickly die. However, a population with high genetic diversity may have an equal number of people with blue, green, and brown eyes. Now, if the blue-eyed killer hits, the population declines, but the damage is limited to a small subset of individuals and the population survives. Though this is a fictitious example, similar scenarios do happen in natural populations frequently.  A population with high genetic diversity (represented here as dot colors) is more capable of surviving a catastrophe or disturbance. Here, only the red and blue genes were capable of surviving, but the population did not die. Had the population had less diversity, perhaps only green and orange dots, the population would have died following the catastrophe. So, in short, trout thrive on human catastrophes. At this point in my research, I would expect nothing less of my study organism.
In the week ahead- it’s (maybe) our last full week of tracking! Hard to believe after six months I can see the finish line. And, I think we are finally documenting the movement patterns we were hoping to see when we started this study. Vague? Yes, but I don’t want to get too excited just yet.  A cold morning at Double Run started most of our mornings the last few weeks. The last couple weeks we’ve started our mornings by standing around the truck in sub -freezing temperatures, pleading with the sun to shine a little brighter. This week, it was back to shorts, t-shirts, and hot breezes. Cruel joke, Mother Nature. Not only is it going to make winter feel a little more bitter, but the trout are now confused about whether it’s time to spawn. My post last week described some of mating rituals brook trout go through before and during spawning. But, I forgot to mention a key part- water temperature! There’s no one set temperature that triggers spawning, but we know that as temperatures drop below 50°F the probability of spawning gets much higher. Two weeks ago water temperatures in my Loyalsock Creek study streams were between 43-47 °F. We were seeing more fish in riffles, regular and moderate rains were keeping stream flows steady, and fewer fish were swimming away when we approached. Spawning seemed close. Then, three days of 70°F+ air temperatures and, more importantly, overnight lows above 50°F, and the streams are now back to around 53°F. Reset the clock. This temperature swing may not seem like much. In fact, it happened frequently during the summer when air temperatures soared into the 90s and forced stream temperatures close to brook trout lethal limits. However, while streams are still fairly cool, in the fall trout are less prepared for quick changes in stream temperature. In the summer, trout are already in deep pools where water is a little cooler. Plus, fish are conserving energy and limiting oxygen demands by moving less. Put another way, trout in the summer are like sunbathers on the beach. They might be hot, but they are lazily lounging and not exerting much energy. In the fall, they become marathon runners and need more oxygen, more energy, and do best when temperatures are lower. This creates the potential for a perfect storm during the fall. Trout need a lot of energy and oxygen to move and spawn. But, they are not consuming a lot of calories because fewer bugs are hatching and emerging and trout are focused on spawning. Warmer water also carries less dissolved oxygen, and trout are seeking shallower riffles and runs which are prone to heating faster than deeper pools. In short, this means that sudden increases in fall water temperature have the potential to be very stressful despite being well below lethal limits.  As water temperature increases, the amount of oxygen in the water decreases. A week ago with water temperatures closer to 8C, there was >11 mg/l of oxygen in the water. Earlier this week, stream temperatures increased to 12C and oxygen dropped closer to 10 mg/l.  One of many bridges in the Loyalsock Creek watershed that fell victim to high floods on October 21st. Photo courtesy of Carol Kafer, Loyalsock Creek Watershed Association. And, that’s only the adults. Trout eggs require oxygen-rich, cool water. If trout spawn before a sudden temperature increase, eggs can quickly suffocate from a decline in oxygen or loss of adequate stream flow. If this happens enough, it could cause complete collapse of an entire year class and could quickly cause an entire population to become extirpated from a watershed.
This highlights the importance of another aspect of climate change that is often overlooked. Yes, there is projected to be an increase in stream temperature in the future. But, equally important is the increased variability and unpredictability in weather conditions. Centuries ago weather patterns were much more stable, making temperature a reliable cue that trout could use when deciding the best time to start spawning. Now that weather patterns are more unpredictable, environmental cues are giving false information about the suitability of habitat conditions. Trout can’t predict the future (and the unreliability of 10-day weather forecasts says humans aren’t great at it, either). It took many generations of evolution for trout to use stream temperature as a spawning indicator. So, it’s unlikely that they will quickly learn that they need to wait a few more weeks before water temperatures are safe and stable. And, water temperature isn’t the only wild card in climate change. There is a fairly narrow range of stream flows that will deliver enough oxygen to eggs while not washing them downstream. And, unfortunately, precipitation is also going to become harder to predict in the future. Just this week Loyalsock Creek suffered devastating flooding that washed away several bridges and many homes. Any trout eggs that were already in the streams likely perished in the high flows. In this, increases in stream temperatures a few days earlier may have saved eggs, assuming the adults survived. Timing is everything, and climate change is busting the clocks for many trout populations.  This redd is fairly obvious (the patch of light gravel), but most aren't this easy to spot, particularly in streams with larger substrate and when the redds are not freshly constructed.
Yesterday I may have tagged the very last brook trout of my PhD. Nearly 200 fish later, it’s hard to believe I closed that chapter of my research. The tracking will continue for at least another month, and we’ll sample again at least one more time for tissue samples, but I have officially tied my last suture. One step closer.
You may recall that in the summer we did several retagging events so that we had most of our tags running at all times. Yesterday was the only retagging for Fall for two reasons. First, between higher stream flows, tagging larger fish, and an improved suturing technique, we are finding fewer dropped tags. Second, we are very close to spawning season. We’ve seen signs of spawning for a few weeks. The fish we tagged in September were starting to show their iconic orange-bellied spawning colors, and yesterday they were in full force. We have also seen fish moving a lot, particularly out of deeper pools and into smaller riffles and runs. These areas of faster moving water carry more oxygen than slow water in pools, making them ideal habitats for females to build their nurseries, called redds. When a female is ready to spawn, she moves into a riffle ½-2 feet deep, turns on her side, and uses her tail to clear silt and sand from around the gravel. If you’re near a trout stream in the next few weeks, keep an eye out for an area of lightly colored gravel with depressions and mounds- you’re likely looking at the trout’s labor and delivery room.
As females are building redds, males are nearby fighting with one another for the right to spawn with that particular female. They ‘strut their stuff’ and chase, bite, and engage in lateral displays until the most dominant male wins the contest and others are chased away from the redd. At that point, a male and female pair have been established, and the female will lay eggs and males release milt into the substrate. The female then uses her tail to make some final adjustments and move substrate around to ensure that the eggs have just enough flow to survive, but not too much that they get washed downstream during high flows.
The video below by my friend Derek Wheaton of Enchanting Ectotherms Photography does an excellent job of capturing redd construction and male competition.  Alveins are had to see because they are burried in gravel. But, they are pretty easy to identify by the large yolk sac that is used for food for about two weeks after emerging from the egg.
Each female releases up to 14,000 eggs, which will overwinter in redds. During this time there is high mortality due to lack of fertilization, floods, predation, or disturbance. But, come spring, the surviving eggs hatch into alevins. At this stage, the fish continue to live in the gravel and feed off of a yolk sac that is still attached to the fish. After the yolk sac is consumed, fish transition into the fry stage and are given a cruel welcome to the real world. Tiny fry consume a lot of energy, and so need to quickly find food, avoid predators, and not get washed downstream. Fry also start competing with one another for access to good habitats, so they need to quickly gain some social skills. Once fry grow a few inches in length, they become parr named for the black ‘fingerprints’ running down their side known as parr marks. It takes about a year for parr to lose those black markings and then, nearly two years after starting as an egg, the trout is now an adult. What a cycle!
During spawning season brook trout are hyper focused on building redds or defending territories. They very often stop paying attention to predators- humans included-and are easy to sneak up on without them swimming away. Many times you’ll see a breeding pair of large trout sitting in the middle of the stream, refusing to move, but ready to eat. The easy catchability and gorgeous bright spawning colors often makes fall a popular time to fish for brook trout. For many states trout season is now closed. But, for states like Pennsylvania where it is still legal to fish for brook trout,
STOP FISHING FOR BROOK TROUT.
At least for a few weeks. Hooking and handling are significant stresses on trout, and juvenile health is a direct reflection on how healthy the parents were during spawning. And, no matter how gentle you handle them, you very likely will cause trout to vacate their territories and seek sub-optimal spawning habitats. Plus, redds are hard to spot with even the most trained eyes, so there’s a good chance you will tromp through and either directly cause egg mortality or interrupt the stream flow the female worked so hard to achieve.
If you hit the streams this winter, remember that redds are active through spring, so keep an eye out and walk on the banks when possible.  If I had to run into a snake, at least it was just a water snake. Typically fairly aggressive, but not when it's cold. Monday was a day I had been dreading for some time. With the fish tagged and recovered, Dan and I hit the streams trying to locate all the new brook trout we recruited into the study (calling them recruits makes it sound like they had a choice in this matter. They, of course, did not.). In the summer, I had basically memorized the location of every fish and they rarely moved. So, tracking was as simple as walking to the fish, fine-tuning the location, and entering the data into the GPS. Now, with 60 more tags, higher stream flows, and movement for spawning season, I have to assume none of the fish are where they were last time. Plus, tags are spread across six frequencies, so it takes a lot more focus and time. But, we tentatively set the next sample date for mid-November, which will also signify the end of fall telemetry. Just keep tracking. The job did get marginally easier, though. We found a few dropped tags which had signs of mammalian predation (teeth marks). We also finally did what I hoped we would never do- tracked a tag into a snake. I had walked around the tag all morning because I was struggling to get a good signal. This should have been the first tip that it was out of the water. I’ve learned that consistently weak signals are usually the result of pointing the antenna in the wrong direction (i.e., only focusing my attention on the stream, and not the banks. Because fish don’t usually wind up land. Keyword: Usually). Right as we were leaving I finally got a signal strong enough to follow and we scampered up a steep slope trying to hone in on the signal. I was traipsing around a tiny area, wondering why I couldn’t get the signal higher. Dan was starting to wipe leaves away looking for the tag when, you guessed it, he pawed right over the snake. The snake definitely wasn’t happy to see us, but thankfully it was a cold morning or otherwise one of us would have surely gotten bitten.  Fish rely on the land for more than just bugs. Here is a brook trout we caught during tagging attempting to eat a frog. I find this feat a little more impressive that the snake. Lost tags are always a little frustrating. The analyses we hope to complete are very data hungry, meaning every fish counts. That said, dropped tags, particularly tags that end up in odd locations, always spark some curiosity. What happened to the fish, and how did the tag end up where we found it? Sometimes I’m curious because we find the tag really far away; much further than it should have traveled in two days. Other times we find tags next to a nest of fishing line (not so hard to figure out what happened to that fish, but I do wonder want the angler thought when they saw the antenna. Robofish?).
When I find a tag with clear signs of predation, it really reminds me that streams aren’t isolated habitats. Fish biologists spend a lot of time with their eyes in the water and it’s sometimes easy to forget that aquatic and terrestrial habitats are intimately connected. The bugs on the land feed the fish, and the fish feed the land animals (among other things). It’s a tight food web that, if interrupted, can really collapse entire ecosystems. This example was set by 4-foot snake that gobbled up a 7.5-inch trout. An impressive feast. And, the only question that remains for me is how the snake feels about having that transmitter pass through its digestive system. We were hoping to track on Friday, but Pennsylvania is currently under a black cloud of rain. Hopefully it eases up by Monday and the fish will have done something interesting. In case you missed it, be sure to check out our special on Pennsylvania Outdoor Life (videos can be found by clicking here). A special thanks to anyone who left comments or feedback, I’ll return all your messages soon! And, if you’re in the area, mark your calendars for October 12th at 7 pm when I’ll be giving a presentation to the Susquehanna Chapter of Trout Unlimited. Come hear more about my research and some early results that are rolling in.
I'm excited to announce that our segment on WNEP's Pennsylvania Outdoor Life aired today. Don Jacobs and Brian Hollingshead did an incredible job bringing our research into the homes of thousands. It's rare that scientists get offered a platform to present our research to a general audience, and I'm glad to see that it's already generated a lot of interest from viewers.
If you saw this segment and want to know more, please let me know! My contact information can be found in the "Who We Are" section above. If you missed it, the videos are posted below, or can be found here and here.  The only way I can identify hemlocks is by the bare branches low on the trunk. These branches don't have needles because they are shaded by the top of the tree. The other day I was in the middle of the stream and took a rare moment to glance up. Towering above were several large hemlocks playing gatekeeper to the hot sun trying to peak through. In addition to being one of the few trees I can identify, hemlocks are one of the most common species of riparian vegetation in trout streams. But, invasive insects are threatening the health of hemlocks, which could have devastating effects on brook trout populations. I know nearly nothing about trees and certainly couldn’t do this topic justice. So, I asked my colleague Erynn Maynard, a PhD student in the Ecology Program at Penn State studying invasive plants, to catch me up to speed on the plight of the hemlocks. Do you have a favorite hemlock grove? If you spend time outdoors in the northeastern United States and in the southern Appalachian Mountains, you likely can think of a place where this species casts their deep purple shade. Within this region, hemlocks flourish in riparian areas near clear, flowing water, and even thrive in rocky outcroppings and stream-edges. Their roots appear to cling and hug to rocks and squeeze between crevices. They are frequently, although not always, accompanied by the graceful sweeping branches and large leaves of the evergreen shrub, rhododendron (Rhododendron maximum).  Not much light reaches the ground (or stream) once hemlock takes over.  The woolly adelgid looks like little tufts of lint hanging onto hemlock tree branches. While the eastern hemlock (Tsuga canadensis) has tiny needles (1/3 to 2/3 inch in length), they are arranged in a single plane along their many branches to provide dense, evergreen shade (a must-have for trout!). Hemlock seedlings can only grow in a dark, moist litter bed, and so they require the deep shade of a hollow and/or other trees to first pave the way and grow large enough to cast shade on the soil below. Once a hemlock seedling germinates, slowly, over many decades, the hemlock will grow and continue to reach for the canopy. Once it inches above its fellow competitors, all other tree species fail to regenerate and only the occasional beech tree will survive in the shady understory. This is why old hemlock stands are what ecologists call a ‘climax stage,’ meaning that the trees species that make up a forest doesn’t change much once hemlock take over. Well, that is until the hemlock woolly adelgid was introduced. The hemlock woolly adelgid (Adelges tsugae) is an insect that resembles an aphid and sucks sap from its host trees near the base of the needles. Its native range in East Asia, the woolly adelgid is usually not capable of killing or even severely impacting the health of its host tree. However, in the United States, trees do not have defenses against the pest, and hemlocks typically succumb to adelgid infestation within five to seven years. If you do have a favorite hemlock grove in the southern parts of the hemlock range, you may have noticed it thin out and lose the purple cast shade over the recent years. Sadly, in many areas, the grove may be gone completely. Why does this matter for brook trout? This thinning of the canopy over coldwater streams allows more sunlight to hit the water causing increased stream temperature in the summer, which brook trout are very sensitive to. In the winter, because air is cold and the ground is warm (comparatively), streams are actually a few degrees warmer when under a dense hemlock canopy and this warmth could facilitate development of brook trout eggs. In some cases, rhododendron shrubs, which have large evergreen leaves, and already existed in the understory can thicken and provide a similar shade and buffering effect. However, in many cases, this shade may also prevent trees from re-establishing at the site, which has many other impacts to the terrestrial and aquatic ecosystems.  Few hemlocks are spared from the devastating effects of woolly adelgid, leaving only a skeleton of the former towering giants.  Map from the US Forest Service showing areas where the woolly adelgid has infestated hemlocks in red, and the distribution of eastern hemlock in green. Rhododendron is also not an equal replacement for hemlock because they are smaller and are not able to regulate water levels in the same way as the larger, denser hemlock. You can think of each hemlock tree as a storage container for water. When it rains, hemlocks soak up water preventing it from immediately flooding streams. When it’s dry, hemlocks slowly release this water back into the atmosphere. So, loss of each hemlock means an increased risk of flooding and less water available during droughts. When trees are able to re-colonize after hemlock departs, they tend to be deciduous trees, meaning that they lose their leaves seasonally and are bare in the winter. Unlike the evergreen hemlock, deciduous trees are not actively storing and using as much water during the winter. This results in higher stream flows in the winter when deciduous trees are dormant, but also lower stream flows during the spring and summer as deciduous trees are using a lot of water to grow and maintain their big floppy leaves. In fact, streams with hemlock have a much lower chance of going dry in the summer than streams lined with deciduous trees in the same watershed. This water regulation service provided by hemlock helps keep stream flows consistent for fish, but also invertebrates. An increased chance of seasonally drying is one of many factors that impacts the abundance and diversity of insects and other invertebrate organisms in the stream. Hemlock streams have more of these delicious creepy-crawlies than hardwood streams do, which may be why some studies have found up to three times as many brook trout in hemlock streams as compared to deciduous streams.  Applying an insecticide around each tree can help prevent infestation, but these practices are not feasible for large, remote forests. What is being done about this? Well, individual trees can be chemically treated with insecticide (on the trunk or in the soil where it is absorbed into the entire tree) to prevent adelgids from eating them. This is obviously time and cost prohibitive in large and remote areas, and is usually only done in parks and landscaping settings. However, this is not a permanent solution, but merely a hold-over to keep large trees alive until predators are established for the adelgid. While the hemlock woolly adelgid was introduced accidentally on shipped plant material, its insect predators were left behind and nothing in the United States finds the adelgid quite as delicious as its predators from East Asia. Currently, there is a mad scramble to find something from the adelgid’s native range that will eat only the adelgid and that can be reared and released here in the United States. But, this type of biological control agent comes with risks as well. It’s difficult to predict what an introduced insect predator will and won’t eat in the wild in a new range. This means that many people are very opposed to intentionally introducing a new non-native species, however, no tree species native to the U.S. will replace the niche of the eastern hemlock.
 A short story behind the American sturgeon and the James River Association is even featured on the label of the Great Return. Continuing with the beer-themed mini-series, but stepping outside of the trout-sphere, this week I’m going behind the name of Hardywood Park’s Great Return. It’s not only a fish-themed beer, but a beer that supports fisheries conservation! Those residing outside of the Old Dominion may not be familiar with the label, but Hardywood is a craft brewery rooted in Richmond, Virginia. Owned by two childhood friends, the brewery opened in 2011 and takes pride in brewing with local ingredients and renewable resources. Nestled in the historic German brewing district, Hardywood is the destination for anything from lively block parties to quiet afternoons in the garden. IPAs are my flavor of choice, so ordering my first Great Return was a no-brainer when it was first released in 2013. I didn’t pay much attention to the name, and it was probably several months before I saw the label and realized it featured an American sturgeon. The Great Return is referencing one of the biggest comeback stories in fisheries, and that’s a cause I can drink to! So, what’s so great about an American sturgeon return? American sturgeon is a large species of fish reaching nearly 10 feet in the length and weighing up to 300 pounds. They are also one of the oldest living species and it is believed they were swimming around at the same time dinosaurs were roaming the earth.  Matt Balazik, a PhD student at Virginia Commonwealth University, leads much of the research efforts on American sturgeon in the James River. Here, he tosses a 70-lb sturgeon back into the river. (image courtesy of phys.org)  In the early 1900s, sturgeon were still regularly harvested in large numbers. (image courtesy of coastalreview.org) Despite surviving the same mass extinction that wiped out the T-Rex, Atlantic sturgeon was listed under the Endangered Species Act in 2012. There are two specific aspects of the species’ ecology that make it particularly vulnerable. First, it takes up to 20 years for a female sturgeon to be able to reproduce. In that 20 years a lot of things can happen, that kill the fish before it is able to reproduce. Most notably, a lot of sturgeon mortality could historically be traced to angler harvest. The first rapid decline in sturgeon populations was believed to occur during colonial times and into the 20th century when sturgeon caviar (eggs) were considered a delicacy and the species was overharvested. In fact, Atlantic sturgeon is believed to have largely prevented massive starvation of early settlers because the fish was large, plentiful, and easy to catch. Today Atlantic sturgeon harvest is illegal; however, adults are still at risk of fatal injury when accidentally caught and from being struck by boat propellers. The other difficultly with Atlantic sturgeon conservation is that they require a wide range of habitats to complete their life cycle. They are a bit like salmon- when not spawning they live in saltwater in the Chesapeake Bay and Atlantic Ocean, but when ready to reproduce they swim into freshwater rivers. Historically, these rivers would have been a safer spot to spawn because there are fewer things to eat the eggs and water currents are not as strong as in the open ocean allowing eggs are more comfortable place to develop. However, in modern times, dams block access to much of the spawning habitat and water quality is so poor that eggs and juveniles can suffocate in sediment-laden water.  Juvenile sturgeon can spend up to 4 years in freshwater rivers before migrating to the Chesapeake Bay and Atlantic Ocean. The above paints the picture of Atlantic sturgeon populations in the James River which flows from the mountains of Virginia, through Richmond, and into the Chesapeake Bay. Historically the James River was home to one of the largest populations of Atlantic sturgeon. Today, it is estimated that only 300 adults occupy the James River every year, and they are all spawning in the same location. This spawning location is unfortunately placed in a section of the river with heavy boat traffic and is regularly dredged to make the river deeper and navigable by large commercial ships. Dredging not only displaces adult sturgeon, but suspends sediment into the water column making the water quality too poor to support Atlantic sturgeon. It would appear that this story ends with having to choose between using the river to support sturgeon, or using the river for commercial hauling (Richmond has a deep history of maritime transportation dating back to the early 1600s that is still alive and well today). However, thanks to valiant efforts by The James River Association and research by university, state, and federal biologists, there are early indications that it may be possible to have both the ecologic and economic uses of the river. Detailed maps of spawning grounds have pinpointed critical areas in the river to protect, and more research on spawning behavior has identified spawning windows in fall and spring when sturgeon reproduce and water quality is of highest importance. Further, through the use of radio telemetry, biologists now have a better understanding of where sturgeon go within the river and the Chesapeake Bay. Together, this information has been used to form an adaptive management plan that minimize risks to sturgeon during critical life stages and protects a larger range of habitats used by the species.  Maps showing the movement of three telemetry-tagged Atlantic sturgeon in the James River. Like the trout, there are some fish (A and B) that don't seem to move much, but others (C) that move up and down the waterway. (image courtesy of Balazik et al. 2012) It’s still early to tell how these management adaptations have effected long-term sturgeon population health, but the observation of more and larger sturgeon entering the James River to spawn has biologists excited about the future. Improved ecosystem management in the James River is a cause that Hardywood continues to support, and they contribute $10 per barrel of Great Return to the James River Association to not only support sturgeon recovery but James River ecosystem restoration.
So, your next drink may very well be saving the Atlantic sturgeon. Bottoms up!  A trout and an IPA. What's not to love? There are two laws in fish biology. Your waders will leak, and there will be beer in the cooler. These rules are common knowledge among anglers and biologists, but also brewers who have enticed many weary fish enthusiast with beers donning a fish-centric name. Some of these beers require no stretch of the imagination- Sculpin IPA (Ballast Point), Striped Bass Pale Ale (Devil’s Backbone), and Wall IPA (Northwoods)- which are all well-known fish species. But some brewers go a step further, intentionally or not, and are able to sell a little fish ecology on every bottle. While my field work continues to crawl along, I felt inspired by the summer heat to introduce a mini-series that goes behind the names of a few beers that may be sitting in your cooler. Up first is Bell’s Two Hearted Ale. This is a certain eye-catcher for any trout enthusiast as the label features an elegant brook trout surfacing through a stream. But, what does a brook trout have to do with two hearts? Bell’s likely named the beer after the Ernest Hemingway short story ‘Big Two-Hearted River’ which makes mention of trout fishing on the river in Michigan. But, I like to think the title has another meaning, one Bell’s likely never saw coming. That is, trout actually have two hearts. The first functions as the normal blood-pumping machine and, in most fish, sits right behind the throat. This four-chambered heart pumps deoxygenated blood to the gills where it fills small capillaries. In the capillaries, carbon dioxide is dumped out of the blood and oxygen is absorbed from the water through a processed called diffusion (which basically just means oxygen molecules move from high concentrations in water to low concentrations in blood). From there, blood circulates up towards the top of the fish, and then heads through the body and towards the tail.  A diagram of basic fish circulation where oxygenated blood (shown in red) moved from gills through the body. Deoxygenated blood (shown in blue) then travels back to the heart through the caudal vein. Once in the tail, blood is largely deoxygenated and sitting in many small capillaries where the pressure isn’t high enough to efficiently pump it back to the heart. So, evolution fixed that problem and gave many fish a second heart, the caudal heart. The caudal heart is located near the last few vertebrae in the fish’s backbone, in a region called the caudal peduncle. The caudal heart collects blood from all the small capillaries in the tail and forces it into the higher-pressure caudal vein where it can more efficiently flow back to the heart. The caudal heart is small (about ½ an inch in trout), two chambers, and is powered by a combination of skeletal muscles and movement of the tail during swimming. Muscle contractions force blood from one chamber of the caudal heart into the other. This second chamber then empties blood into the caudal vein where travels back to the heart. With the first chamber now empty, there is room for many capillaries to each deliver a small amount of blood to the caudal heart and the process starts over again. Interesting, the caudal heart is believed to only be active when fish are swimming, suggesting it is reserved for times when fish are active and in need of more oxygen. So, the caudal heart is kind of like an oxygen mask dropping down when I crank the treadmill up a little higher. Also, not all fish have caudal hearts, and some fish (like eels and hagfish, which both have snake-like bodies) have somewhat different anatomical structures in their caudal hearts. But, the purpose and function of the caudal heart remains the same. So, next time you’re at a bar order a Two Hearted Ale and think about the caudal heart. Or, maybe go trout fishing and think about the ale. Whichever your fancy.  This fish could probably go for a beer. 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.  One of the first pictures of me doing fieldwork. My partner is holding essentially a really long ruler and we would walk around the stream surveying various aspects of the stream channel. 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. |
AuthorShannon White Archives
October 2018
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