Explaining My Research to 10 Year Olds

Me sampling in Sabino Canyon

Me sampling in Sabino Canyon. Photo by Jess Gwinn.

Last week, the Bug Geek issued a challenged to the science blogging community: explain your research to 10-year-olds in 250 words or less.  She’s writing an application that will allow her to do science outreach with kids and part of it is writing a description of her work to 8- to 12-year-olds.  She thought it was a good experience for everyone.  I adore doing outreach and I work with a lot of kids, so being able to communicate to the younger crowd about science is something near and dear to my heart.  So, I sat down and started typing out my response to the challenge immediately.

I promptly ran into a roadblock though: I couldn’t talk about all three areas of research I’ve been involved with in only 250 words.  And it turns out that I wasn’t the only one with this problem!  Ted MacRae at Beetles in the Bush ended up writing one paragraph for his actual work dealing with genetically modified crops and another for his full-time hobby of collecting and describing beetles from around the world.  In the end, I decided to choose only one area of research, my work monitoring aquatic habitats using insects, and focused on that.  Maybe I’ll write two more paragraphs describing my work with giant water bug egg respiration and my dragonfly swarm research in the future, but for now I present my exactly 250 word summary:

Sabino Canyon

Me sampling for aquatic insects. Photo by Dave Walker.

I love bugs!  In fact, I love them so much that I got a job working with them.  I am an entomologist, a scientist who studies insects!  But not just any entomologist.  I study insects that live in the water, aquatic insects.  Did you know there are thousands of species of insects that live in lakes and rivers?  Some have really interesting structures like snorkels to help them breathe or suction cups to keep from being washed away in a river.  They have fun names too, like caddisfly, predaceous diving beetle, and water scorpion!  All of these underwater insects have a place they belong and a job that they do that ultimately help the plants and animals that live with them survive. 

Studying aquatic insects is important because they can tell us about the water they live in, like whether their water has been polluted or flooded.  We often drink the water that insects live in, so we can tell if water is safe and unpolluted by looking at the insects living in it.  If there are a lot of insects that like clean water, then there has been little pollution or other problems in the water.  If you find mostly insects that can live in very dirty water, that tells you that there is something wrong and you can try to fix the problem. 

By studying aquatic insects, I am learning more about our world, but also helping the people who live here.  I have the best job ever!

Me Sampling the Salt River

Me Sampling the Salt River

I work with a lot of second graders, so I think this statement might actually be a bit young for the average 10-year-old.  I adjust how I speak about my work based on the average intellectual level of whatever group I’m working with.  It’s a lot harder to do that in print though!  So, I’m hoping I don’t insult any 4th graders out there by being condescending.

Now, how to summarize why I study giant water bug egg respiration in 250 words or less…  Yikes, that’s going to be a tough one!

(Morgan Jackson at Biodiversity in Focus also took up the Bug Geek’s challenge and described his work with fly taxonomy in his 250 word statement.  It’s really great, so I recommend that you head on over and check it out!)

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

Using Aquatic Insect Tolerance Values: An Example

EDW

A highly impaired, effluent dominated stream downstream of a wastewater treatment plant. Photo by Dave Walker.

Last Monday I discussed how tolerance values are assigned to aquatic insects so that water resource managers and scientists can use insects as indicators of water quality.  While simply knowing the tolerance value of an invertebrate can tell you something about that animal and where it is likely to live, combining the tolerance values of a whole bunch of invertebrates can tell you some pretty profound things about the body of water in which you found them.  Today I’m going to walk you through a large study that I did with my former employer, one in which we examined the aquatic macroinvertebrates in five effluent dominated streams in Arizona, to show you how tolerance values can be used to determine the water quality in a body of water.

Arizona isn’t known for having tons of water all over the place.  We have a lot of people in some areas and a whole lot of agriculture, so the demands for water are high.  As urban and agricultural uses grow, the amount of total available water will decrease until there is very little left.  Water resource managers are thus looking to other sources of water to meet the needs of Arizonans and our aquatic wildlife and sport fish.  One possible source of water is effluent.  It’s possible that many of Arizona’s aquatic animals, especially fish, will depend on effluent dominated waters (EDWs) for survival in the future.

water sampling

Me recording data during a sampling trip to an EDW. Photo by Dave Walker.

Soon after I started grad school, the Arizona Department of Environmental  Quality (ADEQ) became interested in classifying and comparing the macroinvertebrate assemblages of five Arizona EDWs to determine a) the water quality at the outfall from the waste water treatment plant (WWTP) and further downstream and b) whether they represented viable habitat for Arizona’s aquatic organisms.  They gave a grant to my former employer, who hired several students to help, including me.  All of us spent many hours working in some really awful water collecting insects, measuring basic water chemistry, collecting water and algae samples, and measuring the physical characteristics of the stream.  We collected from two sites in each of five EDWs, once during the winter and again during the summer.   Back at the lab, I directed a team of people who sifted through the enormous samples, removed all the macroinvertebrates, and then handed them over to me to ID.  Once I had everything identified to genus and counted, I calculated the diversity and the Hilsenhoff biotic index (HBI) for each site during the winter and summer.

For now I’m going to ignore diversity and focus on the HBI results.  The HBI is an index of pollution tolerance that was originally developed by William Hilsenhoff in 1977 and updated in two subsequent publications.  It’s used by aquatic scientists and water resource managers all the time!  It’s simple conceptually: you determine the tolerance values of many aquatic macroinvertebrates (as described in my post on tolerance values), take a macroinvertebrate sample in a body of water of interest, identify and count all the animals in the sample, and calculate the average of the tolerance values for every individual in the sample.  The resulting number tells you the overall average tolerance value of the macroinvertebrates in the stream.  You can then compare the values you get to this chart to see how polluted the body of water is:

Tolerance values

Pollution levels according to the Hilsenhoff Biotic Index. Click to make bigger! From Hilsenhoff 1987.

For the project I was involved with, I calculated the HBI for each site for the five different EDWs.  I’m not going to name the exact streams so I don’t end up getting sued (one particular WWTP wasn’t so thrilled about what we said about their effluent…), but here’s what we learned.  First, the WWTPs with the better treatment processes had lower HBI’s than the ones with lower quality treatments.  For example, in the best WWTP, water is treated using extended aeration, activated sludge, secondary clarification, and ultraviolet disinfection.  The average HBI for all sites and dates combined for this site was 7.23.  At the worst WWTP, treatment consists of filtering out the solids, running the water through biofilters to remove nitrogen, chlorinating and de-chlorinating the water, and then dumping it into the stream.  From another couple of studies I worked on, I know that the water coming out of this WWTP is full of pharmaceutical products, flame and fire retardants, and other chemicals – and it smells terrible too.  The average HBI for this site was 9.75, which is just about as high as it gets!

EDW

Sampling at an EDW in southern AZ. Photo by Dave Walker.

There were also some overall trends in the HBI values we calculated for each site and date.  The HBI’s were usually higher near the outfall than further downstream, suggesting that the streambed is acting like a filter or the plants are absorbing pollutants from the streams and improving the water quality as it moves downstream.  For example, in the stream below one of the high quality WWTP’s, the HBI at the outfall was 7.5 but dropped to 6.9 further down.  Also, the HBIs were higher in the summer than the winter, 8.4 and 7.5 respectively in one stream.  The reasons behind these seasonal shifts are complex, but the dissolved oxygen levels in the water played a big role.  Generally, things with high tolerance values tend to be able to survive in much lower oxygen environments than things with low tolerance values, and oxygen levels decrease as water temperature increases.  Thus, invertebrates with tolerance values around 6  were probably just getting by in the winter and couldn’t survive at all in the summer, driving the HBI up during the hot part of the year.

The HBI’s of the five effluent dominated streams ranged from 6.5 at a downstream site in the winter at the best WWTP to 9.8 at a downstream site in the summer at the worst WWTP.  Notice that with the exception of the one instance of an 6.5 HBI that falls into the “fair” category, these streams suffer from extensive organic pollution.  One site earned the HBI of 9.8.  Indeed, we found only three species at that site on that date: bloodworms, drain flies, and sludge worms.  Sounds appetizing doesn’t it?

EDW

This EDW looks nice, but it had some pretty nasty water in it. Photo by Dave Walker.

In the end, the HBI values (along with the diversity index we used and our statistics) led us to one undeniable conclusion: none of the EDWs in Arizona are particularly good habitat for aquatic insects.  The oxygen levels are too low and the nutrient and chemical content too high for most macroinvertebrates.  Fish certainly aren’t going to be able to survive in this water over the long term!  In our report we stated that effluent, at least as it is currently treated, is not of sufficient quality to support habitat for most of Arizona’s aquatic organisms and that improved treatment is the only way to make effluent useful for this purpose.  A disappointing recommendation for the water resource managers I think, but it was obvious to anyone who pulled giant handfuls of bloodworms out of a rank, hot, sandy stream when it was 110 degrees outside that this water is far from clean.  In fact, several of the WWTPs recommend that you wash your skin with potable water and soap if you are exposed to effluent.

I’m continuing with the water quality and macroinvertebrate theme next week.  Hope you’ll check back!

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For more detailed information about the Hilsenhoff Biotic Index, consider reading William Hilsenhoff’s 1987 paper (might be a little hard to get your hands on if you don’t have access to an academic library…):

Hilsenhoff, W.L.  1987.  An improved biotic index of organic stream pollution.  Great Lakes Entomol.  20:31-39.

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Unless otherwise stated, all text, images, and video are copyright © 2011 DragonflyWoman.wordpress.com

Friday 5: Aquatic Insects that Suck

For today’s Friday 5, I’m going to discuss five aquatic insects that suck.  No, not that kind of sucking!  These are insects that have suction cups, or suction cup-like structures, that allow them to live in their aquatic habitats.  Now I don’t know about you, but I find it pretty amazing that there are insects with suction cups on their bodies, so I feel the need to share the love!  In no particular order, I present 5 aquatic insects that suck:

water penny

Water penny, top view

water penny

Water penny, bottom view

1. Water pennies.

Water pennies are funky insects – and yes, that IS an insect!  As adult beetles, most species aren’t that exciting, just nondescript black beetles.  But the larvae, pictured here, are bizarre!  These insects don’t have suction cups on their bodies like most of the other insects on my list today.  Instead, their whole broad, domed shaped bodies work like suction cups!  I’ve written about how water penny larvae work before, so I won’t go over it in detail again here.  However, if you think of the little plastic suction cups you use to stick things onto windows, you’ll have a pretty good idea of how the suction works.  You’ll find these living on the tops of rocks in cold, fast flowing streams.

Blepharicerid larva, top

Net-winged midge larvae, top

Net-winged midge larvae, top

Net-winged midge larvae, bottom. The dark, round discs are the suction cups.

2. Net-winged midges.

Ah, blepharicerids.  I can remember the first moment I found one of these in a stream.  I nearly yelled out in utter joy!  It’s one thing to see pictures in a book and quite another to find hundreds of them all over rocks in a stream.  These fly larvae are truly amazing.  They’re bizarrely shaped, even by insect standards, with constrictions along the length of the body.  Each constricted section also contains a suction cup.  Like the water pennies, they live right out on top of rocks in cold, fast flowing streams, so they’re constantly being slammed with water as it flows downstream.  The suction cups keep them from being swept away!  (If you think the larvae of these flies are interesting to look at, I highly recommend that you take a look at the pupae.  Weird!)

predaceous diving beetle

Predaceous diving beetle (Thermonectus nigrofasciatus)

dytiscid foot

Predaceous diving beetle foreleg. The suction pad is made up of several individual suction cups.

3. Predaceous diving beetles.

These are the only adult insects I know of that have suction cups.  And, they don’t use their suction cups to prevent their washing downstream like most aquatic insects with suction cups.  Any idea what they might be used for?  Hint: only the males have them.  These suction cups are used during mating!  Predaceous diving beetles are extremely well adapted for swimming and exhibit very smooth, domed bodies that allow them to move through the water with surprising grace.  If you’ve ever tried to pick one up with forceps, you know how slippery these little buggers are!  This causes problems when a slippery dome-shaped male wants to climb onto his slippery domed-shape mate’s back and get down to business.  So, they evolved suction cups on their forelegs!  You can see them there in the photo – lots of little suction cups making up a big suction pad.  The male presses the suction pad onto the female’s back and is able to hold on long enough to mate.  Pretty neat, eh?

Rhithrogena impersonata

Rhithrogena impersonata. Photo from http://www.troutnut.com/specimen/482.

Rhithrogena impersonata

Rhithrogena impersonata, bottom. Photo from http://www.troutnut.com/specimen/482.

4. March brown mayflies.

Mayflies in the genus Rhithrogena (family: Heptageniidae)  are rather similar to the water pennies in that they do not have true suction cups.  Instead, they have flat bodies and their abdomens are ringed by broad, flat gills.  The space between the gills works like a suction cup and keeps these mayflies attached to the rocks on which they live in streams.  While these nymphs are not dome shaped like the water penny larvae, their suction cup works in a similar manner.

Leech

Leech. Leech sucker is inset.

5. Leeches.

Leeches are not insects.  In fact, they’re not even arthropods!  However, they are aquatic and they definitely have suction cups, so I’m including them in my list.  Leeches use their suction cups to grab the substrate or to hold onto their prey as they suck their fluids.  I also personally think they add to the overall distasteful appearance of these animals.  I mean, what’s not to love about an animal that uses a sucker at one end to attach to you and a sucker at the other end to suck your blood?  :) (Okay, I’ll admit that I do actually like leeches.  Ever seen one swim?  It’s both horrifying and mesmerizing and I can’t tear my eyes away!)

Don’t know what I’ll do next week!  I have a long list of ideas, so it will depend on my mood when I sit down to write.  Maybe something Christmasy!

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Unless otherwise stated, all text, images, and video are copyright © 2010 DragonflyWoman.wordpress.com

Notes from NABS Day 4

meeting logoIncorporating Service Learning Into an Introductory Limnology Course

Greetings from NABS Day 4!  Tomorrow is the last day of the conference, so I’ll only be making one more post in this series.  I’m also headed home, and a bit earlier than originally planned.  A combination of sleep deprivation and general physical and mental exhaustion due to extensive traveling over the last few weeks (I was gone almost a week right before the conference began) has convinced me that I should go home in the morning, skipping the talks on the last day of the conference.  I’m driving home, so it’s important that I travel during the period when I am most alert, which means missing the talks.  So, I will be presenting something from one of the first four days of the conference when I post my final entry for the conference on Saturday.  What can you do?

Things I learned:

— High school students have a lot of fun going out into the field to collect data (though this shouldn’t come as a surprise – my favorite biology lab in high school was one where we documented the ecosystem of a marsh in Colorado, the same marsh where I eventually did my undergraduate biology thesis!)
— Aquatic insect species that are found in many areas across the landscape are usually found at about the same altitude while insects that are found in a wide range of altitudes are typically only found in a small geographic area.
— This is really re-confirming something for me:  conferences are exhausting!

On to my favorite talk of the day!  I attended the Education in Aquatic Sciences session today because this subject is near and dear to my heart.  I LOVE teaching, so any time I can learn more about how to do it better, you know I’ll be there in the front row.  (Okay, okay – so, I was in the second row…)  My favorite talk of the session ended up being my favorite talk of the day, partly because it was an interesting talk and partly because the speaker, Dr. Frank Wilhelm, was completely inspiring.  Dr. Wilhelm is a professor in the University of Idaho’s Fish and Wildlife Resources Department and teaches a course in introductory limnology to undergraduate students.  His talk focused on a service-learning project that he has incorporated into his class and he described how it works.

Service learning is defined as a method of teaching, learning, and reflecting that combines classroom curriculum and meaningful service throughout the community.  In essence, service learning projects allow students to doing something hands-on that is also worthwhile to the community.  Dr. Wilhelm described service learning as a powerful, motivating, and effective approach to teaching and learning and believes it can be broadly applied in college courses focusing on field-based sciences.  He also believes that it engages students in a way that isn’t possible via other teaching methods and helps the students form a strong connection between what they learn in class and the real world.

Here’s how the service learning component of Dr. Wilhelm’s intro limnology course works.  First, he finds someone or a group of people in the community that have a problem they want solved or a question they want answered.  That person or group then becomes the partner for the class that semester.  Dr. Wilhelm gave an example of a partner from the last class he taught.  In his area, there is a small lake that is surrounded by ritzy homes.  However, the lake was absolutely full of vegetation, so full that it was completely useless for any other purposes such as fishing or boating.  The neighborhood asked Dr. Wilhelm to have his students tackle their problem and became the class service learning partner for the semester.

Students are told at the beginning of the term that they will be doing a service learning project as part of the course.  It is a required activity that ends up taking up the final 1/3 of the lab periods of the course.  During the first week, the students are put into groups that become their team for the semester and the entire class is introduced to the problem.  The second week, the partner presents the problem to the class so that the students know the person/people they are helping and the problem they are trying to solve.  They then identify subsections within the main problem that individual groups can tackle during the course.  Teams decide which subsection they want to focus on and define clear objectives, develop methods, make lists of equipment they require (made available by Dr. Wilhelm from his personal supply), and develop a budget that will help them accomplish their goal.  Dr. Wilhelm allows his students nearly complete freedom to decide which aspects of the problem they wish to tackle, how they wish to tackle it, and what sort of data they will need to collect.  His only requirement is that they have to work toward solving the overall goals of the project.

Then he sets them loose out in the field to do their projects!  By his account, this part is a little chaotic, but the students generally have fun and are learning valuable things while they work.  Dr. Wilhelm also said that students use their travel time to discuss issues related to the project, so there isn’t any downtime – they are constantly learning.

Back in the lab, the students analyze the data they collected in the field and make conclusions based on their results.  Then they present their part of the project to the rest of the class in teams.  The students combine their efforts to create a report that they will present to the partner.  And then they present their data to the partner in person, making suggestions for how the partner might solve their problem.

Dr. Wilhelm said that this sort of project is fairly easy to incorporate into a class that could conceivably have a field component.  (I can imagine how well it would fit into my insect behavior and aquatic entomology labs!)  He said that all you need to get started is to identify a partner for the semester, identify the areas of expertise for which you have sufficient knowledge to successfully guide students toward solving the partner’s problem, and spread the word about the program to get people interested.

Dr. Wilhelm believes the program has been a big success.  The partners have been happy with the information the students have provided them.  The students themselves tell Dr. Wilhelm that they really enjoy the project and think it’s the best part of the class.  Dr. Wilhelm thinks his students have become more engaged in the course since he introduced the service learning project as well.  Perhaps the best measure of success is that, in a difficult senior level undergraduate course worth 4 credits that starts at 8AM, he has nearly 100% attendance!  This just doesn’t happen.  He attributes this spectacular feat to the service learning project experience.

Although the talk was simple and not a scientific research talk, I really loved this one.  If nothing else, Dr. Wilhelm obviously cares about his students deeply and wants them to succeed.  He puts a lot of effort into his teaching and is clearly excited by the teaching component of his professorship (a somewhat rare trait at the big public universities!).  It was so inspiring to listen to him talk about his program and how involved the students become, how much they care about what they’re doing during their service learning project.  I’m hoping to incorporate some of the same things into my own courses sometime!

Tomorrow I’ll finish up Notes from NABS with a description of a talk I heard on Day 3 that focused on the effects that a small wildlife preserve has on a river in southern Michigan.  The vegetation that would naturally surround the river (called the riparian area) has been entirely replaced by agricultural fields – except for the area where it flows through the preserve.  Want to know if this preserve helps improve the quality of the water before it flows downstream?  Check back tomorrow!

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Posts in this series:
Day 0 – Introduction to the Series
Day 1
– Invasive Crayfish
Day 2 – Giant Water Bug Dispersal
Day 3 – Dragonfly Captive Rearing
Day 4 – Integrating Service-Learning Programs into College Courses
Day 5 – Impact of a Small Preserve on Stream Health

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Unless otherwise stated, all text, images, and video are copyright © 2010 DragonflyWoman.wordpress.com.

Notes from NABS Day 1

meeting logoTrophic cascades, detrital dynamics, and invasive crayfish

Welcome to my summary of Day 1 of the NABS/ASLO joint meeting, almost live and definitely on location!  I’ve decided I’m going to start each NABS meeting posts with a short list of things I learned during the previous day.  Here goes!

Things I learned yesterday:

— There are a whole lot of invasive fish species in the world and they can cause massive problems in stream systems.  The round goby is a big problem in the Great Lakes region and the armored catfish dominates some rivers in southern Mexico (and is feared by the locals who think the fish is poisonous).
— Dams and other barriers to fish can cause nitrogen shortages in streams above the barriers.
— Global warming could cause a downward shift in body size in a huge variety of organisms because body size generally goes down as temperature goes up.

My favorite talk at the meeting yesterday was the one titled above.  For my entomological or scientific readers out there, this title likely makes sense.  For the rest of you – don’t worry if it doesn’t!  We scientists use a lot of big words that normal, er, I mean, non-scientific, people wouldn’t ever have a reason to know.  Let’s go over the concepts in the title before I get into the content of the talk.

I’m going to start with detrital dynamics.  Detritus is a fancy word for biological debris or debris made up of organic matter.  In aquatic systems, detritus is typically made up of plants parts (such as leaves that have fallen into the water), dead algae, and the occasional dead animal.  Detritus is an important food source for many aquatic insects, so a lot of aquatic scientists will put mesh bags full of leaves into streams and see what happens to them as part of their studies.  This is what detrital dynamics means: how detritus in a stream or lake is processed and broken down by the organisms living in the water.

Invasive means exactly what you think it might mean.  An invasive species is an organism that has invaded another environment, a habitat in which it has not lived before, either naturally or via human activities.  Most of the time, invasive species are problematic.  For example, yesterday I learned that round gobies were probably transferred from their native habitat to the Great Lakes in the ballast water of tansoceanic ships that entered the Great Lakes.  The species does well in the Great Lakes and is causing problems for native fish.  It is currently expanding its range into the streams that flow into the lakes.

Trophic cascades are a little more complicated.  Most people know about food chains or food webs.  Let’s quickly review the concept.  At the bottom, you have producers, things like plants and bacteria, that convert solar energy or other forms of non-organic energy into body mass.  Then you have the herbivores.  Herbivores eat the producers, converting the energy they get from digesting the producer into their own body mass.  Then you have the predators, the carnivores.  These organisms eat the herbivores to develop their body mass.  The producers, herbivores, and predators form what are known as trophic levels, groups of organisms that have similar feeding requirements and styles.  The suffix “troph” refers to food, so any time you see this term used in biological terms you know you’re supposed to consider food or feeding modes.

In the past, biologists used to think that the relationships between these organisms was a simple chain or a simple web: a predator eats an herbivore that ate a producer.  They didn’t think that a predator had much of an impact on other predators or the herbivores it didn’t eat, and early biologists definitely didn’t expect that the predator would have any impact on the producers.  We now know that this is a considerably oversimplified way to think about the relationship of organisms in nature and that the relationships among and between trophic levels can be incredibly complex.  As an example, consider a bird species that eats grasshoppers.  The birds love grasshoppers and eat as many as they can.  Because the birds are eating the grasshoppers, they are decreasing the number of grasshoppers in the population.  This in turn allows the grasses and other plants the grasshopper consumes to grow better because there are fewer grasshoppers eating them.  So, the bird has an indirect affect on the grasses.  And this is what is known as a trophic cascade: one organism impacts an organism in the next lower trophic level, which in turn impacts the next lowest trophic level, etc.  Everything is kept in a sort of balance, at least until something comes along to change that balance.  And that brings me to the subject of the talk I liked most yesterday: the signal crayfish.

signal crayfish

The signal crayfish. Photo taken from Wikipedia.

The signal crayfish (Pacifastacus leniusculus) is an American crayfish that has become an invasive species in certain parts of the world.  They’ve been purposefully introduced into streams in Europe on more than one occasion and they’ve been transported beyond their natural range within the United States as well.  They’re omnivores and they eat almost everything they can get their mouthparts on, including several things that other organisms have a hard time eating.  As a result, they can cause major problems if they become established in an area outside of their native range.

Dr. Jonathan Moore of the University of California Santa Cruz studied the species in a stream in northern California, Scott Creek, where the crayfish is an invasive species.  He suggested that biologists still don’t have any means of accurately predicting what will happen if a species is added or removed from a stream because we don’t understand how everything ties together in a system.  He stated that trophic cascades are really more like trophic tangles, masses of interactions that we can’t disentangle from one another.  Some of his work focuses on trophic cascades and what happens when a species is eliminated or introduced into a system.

The study he presented was one in which he looked at the effect of the presence of signal crayfish on the populations of aquatic insects, algae production, and leaf litter processing in Scott Creek.  To do this, he did two different studies, one short term experiment and one long term observational study.  For the short term experiment, he compared the aquatic insects, algae levels, and leaf breakdown in small, isolated pools with various numbers of crayfish in them.  In the long term experiment, he looked at the same factors in pools that had never had crayfish in them compared to pools that had crayfish.

Dr. Moore found that in the short term, signal crayfish decreased the number of aquatic insects in the pools significantly.  This in turn allowed an increase in the amount of algae to occur, likely because the insects were not as abundant and were not able to eat as much of the algae in the pool and the crayfish don’t eat as much of the algae as the insects do.  He also found that leaf breakdown increased with an increase in crayfish abundance in the pools.  The crayfish were eating the leaves, so the more crayfish, the faster the leaves were broken down and consumed.

In the long term, Dr. Moore found similar results.  The number of aquatic insects was higher in pools without crayfish compared to pools containing crayfish.  The algae levels were higher in pools with crayfish than in those without.  He didn’t see the expected result with the leaf litter though: pools with and without crayfish had nearly identical leaf breakdown rates.  He attributed this to the fact that pools with low or no crayfish in them had more insects, particularly caddisflies, that broke the leaves down in the place of the crayfish.  So, the leaf litter being broken down or consumed at similar rates regardless of which organism was doing the work.

The take home message with which Dr. Moore ended his talk was that the impact of an organism on its environment is a combination of direct and indirect effects.  He also suggested that these direct and indirect effects can operate on distinctive timescales as evident from differences the leaf breakdown rates in the short and long term studies.  He then emphasized the importance of these types of studies so that we better understand the relationship between organisms and might someday be able to predict what will happen if a species is added or subtracted from a system with more precision.

And with that, I’m off for another day of talks!  Tonight I am also doing my presentation, a poster on my work on the respiratory behaviors of the giant water bug.  I will not talk about my own work tomorrow and focus instead on another talk I find interesting, but I’ll get back to my own research eventually.  Hope you’ll check back again tomorrow!

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Posts in this series:
Day 0 – Introduction to the Series
Day 1
– Invasive Crayfish
Day 2 – Giant Water Bug Dispersal
Day 3 – Dragonfly Captive Rearing
Day 4 – Integrating Service-Learning Programs into College Courses
Day 5 – Impact of a Small Preserve on Stream Health

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Unless otherwise stated, all text, images, and video are copyright © 2010 DragonflyWoman.wordpress.com.

Notes from NABS

meeting logoGreetings from a new venue for the Dragonfly Woman!  I’m currently in Santa Fe attending the joint meeting of the North American Benthological Society (NABS) and the American Society of Limnology and Oceanography (ASLO).  I’ve been to NABS meetings in the past and they’re quite fun as far as scientific meetings go.  You spend your days going to scientific talks (and there are TONS, so it’s not hard to find at least one thing you’re interested in during any given time slot) or poster sessions and your evenings socializing with the other members of the society.  The NABS meetings are far and away my favorite meetings to go to of all of the scientific meetings I’ve been to because they’re a reasonable size and really emphasize the social aspects of the society.  As a not-at-all-outgoing person, I appreciate this.  Forced scientific social time is good for me.  :)

This year… well, I can’t say the meeting is going to be quite as fun for me, though I’m sure other people would heartily disagree.  There are double the people at the meeting due to the addition of the ASLO members, and I find the crowds disconcerting.  The social activities are, I’ll admit, a bit overwhelming for me due to the gigantic number of attendees and that makes them far less fun for me.  The meeting is also spread across several buildings for the first time since I’ve been attending the NABS meetings.  This wouldn’t be a problem if the buildings were close together, but some of them are several blocks apart.  This makes scheduling your day a lot more complicated because you can’t just flit from room to room easily like I have in the past.  I feel obligated to sit through talks I’m not as interested in hearing because something better is too far away to get to in time.  And then there are a bunch of little personal touches that the NABS meetings always include that are absent from this meeting, making it feel just a bit less special.  None of these things are the end of the world of course and I’m sure I’ll enjoy the conference anyway, but they do make the meeting marginally less appealing to me than in former years.

The meeting officially started yesterday.  I hadn’t planned to go to the opening ceremonies last night, but even if I had, I wouldn’t have made it to Santa Fe in time.  When estimating how long it would take to get to Santa Fe by car, I stupidly used the time it took to get there from where I used to live in Colorado rather than Tucson, even though I’ve driven both ways a hundred times.  That combined with being hit by an absolutely enormous, blinding storm on the interstate in the dark meant that I arrived much later than planned and completely missed all of the things that happened last night.  But that’s okay.  I did get to see a spectacular sunset shortly before the mother of all storms slammed into my car and that made the drive 100% worth it.  This photo doesn’t even begin to do it justice (it was, after all, taken one handed and out the window of a car going 75 mph on the interstate and I certainly wasn’t taking my eyes off the road long enough to frame the shot properly – not ideal photographic conditions!):

sunset

Sunset in New Mexico

Because I missed the official first evening, I consider today day 1 of the conference.  And this means that, as promised, I am going to try to blog every day this week and highlight my favorite talk or poster of the day.  Just as a warning, I might jump outside of the aquatic insect realm this week.  This isn’t an insect meeting and there are tons and tons of other aquatic related topics covered here that I find fascinating, so one non-insect talk might work its way in.  My favorite talk today did at least deal with another freshwater invertebrate: the crayfish.  It was a very interesting talk and I am very excited to share some of the information that was presented.

However, you won’t get to hear about it until tomorrow.  I am going to have a one day delay in getting things posted (Day 1 will be posted on Day 2, etc).  This is to ensure that I have enough time to get a decent post together rather than throwing something up that doesn’t make sense.  I will have a new post every day through Saturday though, so I hope you’ll check back often.  There will be some very interesting and very new science posted over the next 5 days.  It should be worth your while!

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Posts in this series:
Day 0Introduction to the Series
Day 1
Invasive Crayfish
Day 2Giant Water Bug Dispersal
Day 3 Dragonfly Captive Rearing
Day 4Integrating Service-Learning Programs into College Courses
Day 5Impact of a Small Preserve on Stream Health

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Unless otherwise stated, all text, images, and video are copyright © 2010 DragonflyWoman.wordpress.com.

Building a Garden Pond for Aquatic Insects, Part 5

pondThe Educational Value of an Insect Pond

If you’ve kept up with my last 4 posts, you know that I’ve built a pond at the Biosphere 2 as part of the fellowship I have through B2.  Because I’m an aquatic entomologist, I built the pond specifically to attract insects.  For more details on how the pond was installed, why I chose to include particular things in the pond, and suggestions for building your own insect pond, see my previous few posts!  Today I’m going to talk about my educational display as a whole, the experience the pond was built to be a part of.

As I said in my first post in the series, I believe the best way for people to learn about aquatic insects is to see live insects.  The focus of my display is my pond so that B2 visitors can see live insects swimming around and doing the things they normally do.  If everything goes as planned, the pond will attract several insect species (including several beetles, mayflies, backswimmers, water boatmen, bloodworms, etc) from the surrounding area that will then colonize the pond.  However, simply having people look at the insects has almost no educational value.  To actually teach visitors something about the insects they find in the water, I created educational signs and identification guides.

My signs focus on two different topics, aquatic insects of the Sonoran Desert and dragonflies and damselflies:

aquatic insects sign

Aquatic insects sign

dragonfly sign

Dragonfly sign

I know you can’t read the text in the signs, but let me tell you a bit about them.  The aquatic insects sign focuses on something that is related to the work that I do: how the types of aquatic insects you find in a body of water can tell you important things about that body of water.  Aquatic insects are found in almost all exposed freshwater, from a huge river to the water that collects in the base of your flower pots.  Aquatic insects also depend on the availability of water for their survival and reproduction.  This makes them excellent indicator species, species that tell us about the characteristics of a particular aquatic habitat.

In my aquatic insects sign, I discuss two different things that aquatic insects can tell us: how clean the water is and whether the water normally flows or not.  Many federal, state, and local governmental organizations rely on insects to tell them valuable things about how clean the water is.  Over the past 30 or 40 years, scientists have been observing insects they find in different types of water and assigning them pollution tolerance values.  These tolerance values are based on the characteristics of the water in which the insects are typically found and can be inputted into mathematical formulas to tell an agency how clean the water is.  I’ve done several projects that use insects as indicator species of aquatic habitat quality and it is a valuable means of quickly determining how clean the water is.  I’ll discuss this idea further in a future post.

Insects can also tell us whether the water usually flows or not.  Most aquatic insects have a preferred habitat, the place they most like to live.  When you see enough habitats and collect enough insects, you start to see patterns in their distribution.  For example, the insect called a hellgrammite (the larva of the dobsonfly) is usually found in fast flowing, relatively cool water.  It is also long-lived for an insect, spending about 3-5 years underwater before it pupates and then emerges as an adult.  If you find a hellgrammite, you know that the water in the system generally flows year-round and is often cold because they require 3-5 years of fast-flowing, cool water to survive.  Knowing which insects belong in which types of conditions can tell you a lot about a system based solely on the insects you see in that system.  It is also possible to tell whether disturbances have occurred in a system by looking at the insect population.  For example, if you were to look into a pond and find a hellgrammite you might suppose that the area has been experiencing a drought, perhaps drying a flowing stream sufficiently to form ponds.  A hellgrammite wouldn’t normally be found in still water, so you know there’s something abnormal going on in that system.

My dragonfly sign focuses on my favorite insects, the dragonflies.  It’s a simple sign that talks about the life cycle of dragonflies (they are hemimetabolous insects, so they have three life stages – see my post on metamorphosis for more detailed information) and how to tell the dragonflies and damselflies apart (see my posts on how to tell them apart as adults and nymphs for more info on this topic).

Both signs introduce a topic, pose a question for the visitor to answer on his or her own, and then directs them to identification guides that will help them identify the things they are most likely to see.  The dragonfly sign asks visitors to look for dragonflies and damselflies in the places they are most likely to be and suggests that they identify any they observe using the dragonfly ID guide.  The aquatic insect sign asks them to look into the pond to see which insects a typical Sonoran Desert pond, one that contains still water year-round, will contain.  They are encouraged to use the aquatic insect ID guide to identify the insects they find in the water.  Both guides include photos, the scientific and common names of the insect, some of their obvious identifying characteristics, and suggestions for where to look for them in the pond.  The ID guides were printed in color, laminated, and hung off the side of the pond via binder rings for easy access:

ID guides

The ID guides hanging from their hangers on the pond.

I hope they will get good use for several years!  I have also made the ID guides available here for people to download if they wish.  This introduced all sorts of copyright issues for the images I was originally intending to use, some gorgeous line drawings from an aquatic entomology book that is otherwise dated, so I ended up using photographs instead.  Most of the photographs are my own, but I would also like to thank Bob Behrstock for providing images for most of the damselflies that I was missing.  Be sure to check out his amazing insect photographs on his website!  To download the ID guide files, please see my Educational Materials page.  I will leave them archived here for as long as I am able.

And that wraps up my pond series for now!  I’ll give a brief update on how the pond is doing in May after we have the final meeting for my cohort of Biosphere 2 Science and Society fellows and I have a chance to check up on it, but I think my pond is largely on its own at this point.  All in all, I thought the pond-building experience was a good one.  It ended up being a lot more work than I’d expected because I got less help at every stage than I had expected, but what doesn’t kill you makes you stronger and better educated, right?  I learned a lot while building this pond and it’s an activity I would highly recommend that other people try.  If I could do it, anyone can!  It wasn’t all that expensive (about $600 for the tank and all of the supplies) and the above ground tank made everything pretty easy in the construction phase.  Plus, you get to use power tools, and that’s always a good thing.  You can’t beat the end product – a gorgeous pond full of green plants and amazing insects in your yard.  I am looking forward to the day when I can build a pond in my own yard and enjoy the dragonflies and other insects that will use it.  I’m sure it will be even easier the second time around!

Until next time, I leave you with a photo of my entire display (pond, signs, ID guides, and all) in the lovely orchard courtyard of the B2.  If you have a chance to visit B2 and check it out, I hope you’ll stop back here and leave comments!  I’d love to hear what people find in the pond and how they like the display – and I’m always happy to answer questions too.

educational display

The final product of my permanent educational display at the Biosphere 2.

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Posts in this series:

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Unless otherwise stated, all text, images, and video are copyright © 2010 DragonflyWoman.wordpress.com.