The lesson plan I created for the first day of FOR242 is true to what occurred in the classroom on Thursday, January 14, 2016. I will admit, although I had thought through the class several times, I had only written a brief list of how I wanted class to go. Since writing this lesson plan, I have written the subsequent lesson plans to date and will continue to do so. Also true to the class, the session is 160 minutes instead of the typical 50 minutes. Therefore, I feel it is particularly important to change approaches several times in order to keep both my own and my student’s attentions.
Here are my thoughts as I developed the following:
Lesson Title (Phrased as a question)/ Learning Objectives/lesson goals
Creating a lesson title seems simple enough, but phrasing it as a question threw me for a loop. Frankly, I could not find a satisfactory answer online as to why a lesson title should be phrased as a question. The students won’t see it and likely few to no other faculty will see it either; so, I find myself asking how important is this?
Now that I know how to write a clear objective, it is very helpful to explicitly state these at the beginning of a lesson. I am able to ask myself how my lesson contributes to students successfully achieving the objective.
To me, the lesson goals help place a particular lesson into the overall scope of the course. If I cannot justify it in the larger picture, perhaps the lesson is missing the mark.
Gain attention and tap into prior knowledge/Interest Approach/Hook/Anticipatory Set
I like starting class with some sort of warm-up activity. This allows the students to shift from whatever was happening before class to a learning mind-set. Beyond the first day of class, I like to use this opportunity to ask the types of questions I would use on an exam. This serves two purposes: 1) Students can anticipate what my exam will be like and 2) I can gauge how well students are grasping the material. However, on the first day of class I used the warm-up as a precursor to our class introductions. By creating “business cards”, not only did I get to know the students faster, I had flashcards to study the student’s names! Additionally, this pulls from student’s prior knowledge of jobs available to them, although I hope to expend on this throughout the semester as well.
Input/teaching/Summary of Teaching Methods
This section was initially hard for me to design. I had tried to follow Dr. Foster’s formatting of a lesson plan, but I found that his style was too hard for me to follow. Therefore, I created my own table layout. There are three columns to my table: time, activity and description/instructions. The description/instruction column is detailed enough for a colleague to follow, but leaves enough room for interpretation as well.
Within my lesson plan, I tried to mix-up who was doing the talking; typically every-other activity switches the attention from students to instructor. Also, I was sure to change up the way information was being conveyed (e.g. PowerPoint, unsupported lecture, discussion).
In this particular lesson, introductions and review of the syllabus are necessary first day activities. I only see these students 15 times; so, I believe it is important for me to get to know the students quickly and for them to get to know me as an instructor. Also, it is important I lay the framework of the course through the syllabus to set the tone for the rest of the semester. I prefer taking the time to set the framework for the semester, rather than jumping right into lecture materials on the first day of class.
Since this course is partly discussion based, covering potentially controversial topics, I like the triangle activity because it is a low risk situation for students to put out their thoughts to the entire classroom. In addition, it’s fun (with a purpose of course!).
Lastly, I expect students to write well for this course; therefore, I attempt to set them up for success by conveying these expectations. Previously, students have had difficulty structuring their arguments; so, I review a basic 5-paragraph essay with the idea of including a claim, data to support the claim, and a warrant to connect the data to the claim. We then look at examples written by a variety of authors based on topics related to the environment. These essays are available online through NPR’s This I Believe website.
Application/Guided practice with feedback
This activity (This I Believe) was given a longer timeframe than most other sections of the lesson plan. However, because the guided practice was based on 4 different scenarios (and the relative importance of grasping this topic), I was ok with this. In my mind, the 60 minutes was divided into smaller activities, which did not make a 60 minute chunk of time seem as if it lasted forever.
Independent practice/assessment (ex. Homework)
Homework in this course is primarily essay based, which is why I tried to lay out my expectations for writing during the first week. I expect that students will apply what we talked about (claim, data, warrant) as they write their opinions of chapters read from their text. Not only does this show me that they comprehend what is going on, but I realize not everyone is keen on class discussions. Short papers allow for me to know what the student is thinking and engage in another forum.
Closure Wrap Up/Cognitive Connect/Show what you know in class!
To me, this is a time for me to emphasize take-home messages and give reminder announcements. I know that my class is not the only class students have on their plate so I try to take the time to summarize the day’s class.
Overall, I was please how the first day of class went. I wish I had had this lesson plan at the time, but I look forward to having them in the future.
Monday, February 15, 2016
Tuesday, February 9, 2016
What is the "Entomologist's Hat"?
“The second someone find out you took an insect course, you automatically wear the entomologist’s hat.”
These words have been repeated to me countless times as I have taken and been the TA for a freshwater entomology course at Penn State. Even on the first day of the course, the instructor forewarns the students that family and friends alike will expect the students to know every insect they encounter for the rest of their life. Not only is this physically impossible, but our fifteen week course is restricted to larval aquatic insects which makes up such a small proportion of the globe’s insect fauna. Regardless, this is what he refers to as the “entomologist’s hat.” So weather you wear multiple hats or have a cap with lots of feathers in it, join in the conversation.
What are your hats?
Wednesday, February 3, 2016
Syllabus: A Critical Review
The syllabus I chose to use for this assignment is the syllabus I created for FOR242: Elements of Project Supervision in Forestry. The title of the course is highly misleading; however, this is out of my control. If I were to change the title, I would change it to: Wildlife Policy and Current Events.
My syllabus underwent several changes from last year (Spring 2015) prior to the beginning of the Spring 2016 semester. This primarily included formatting of headers and organization of information. Although minute, I changed the font to match that which I require under my formatting policy. I chose to lead by example. Other major changes included an updated office on Dubois campus, discrete office hours (now that I have an office at Penn State Dubois) and the elimination of my cell phone number (I did have students text me questions instead of email me). Therefore, on my latest syllabus, I indicated that email is my preferred method of communication.
At the beginning of this semester, I chose to eliminate last year’s objectives because they were poorly written and include a course overview instead. On my latest syllabus, I have rephrased the course overview and reinforced the major objectives of my course. I believe that the focus and direction of the course is clearer not only to myself but my students as well. Additionally, I have several updated policies:
1. Attendance - This year I added attendance to the grading scheme in hopes that students might be less inclined to schedule meetings with other professors or interviews during my class. While I understand that life happens, it is discouraging to see the lack of value students put on my class. After a discussion with Dr. Cindy Raynak, she suggested changing “Attendance” to “Participation”. My initial policy indicated as long as students were physically in a chair, they would receive a point and students will do anything for a point. To encourage more participation, I should call it just that.
2. Cell phones and Other Electronics - Last year I did not even think to have this policy, but it quickly became clear that I needed one. I struggled with the language I wanted to use, but I needed students to see how serious I am about the policy.
3. Examinations - Somehow I missed including this policy in 2015 and at the beginning of 2016. However, I wrote a short statement to cover the single exam I have in this course. It was difficult to find examples of this policy online as a basis for my own. However, I think this covers what I need.
4. Formatting - Last year I received a barrage of formats for writing assignments. This year, I included a policy for consistency as well as a sense of professionalism.
5. Late Assignments - Last year I did not have a late assignment policy which came back to bite me. Therefore, I was sure to include it this year. This policy was based off of a policy from an instructor who I respect and whose teaching style I try to incorporate into my own.
Another change that I made, per the suggestion of Dr. Raynak, is putting my “Grading” and “Points” sections together. This way, students have all of the information they need in once place. In addition, Dr. Raynak suggested including the point values for the ranges of each grade. This way, students do not have to do the math to see what grade they are getting. Her point was that students should work on the course materials instead of working on the syllabus to see what grade they will receive. With some thought, I finally agreed with this scenario and added the point values under “Grading”.
Another change that I made this year was related to the “Course Schedule” section of the syllabus. The change I decided to make was to include the Taking Sides Topics in the syllabus instead of another document as I did last year. Students had to use too many resources to figure out what chapter they were to read for class. Additionally, I included the corresponding chapters to help alleviate confusion.
Overall, I have become much more confident with my syllabus and my course as a whole. Being able to clearly communicate my goals and expectations to the class will help their performance as well as enhance my overall delivery of the course.
My syllabus underwent several changes from last year (Spring 2015) prior to the beginning of the Spring 2016 semester. This primarily included formatting of headers and organization of information. Although minute, I changed the font to match that which I require under my formatting policy. I chose to lead by example. Other major changes included an updated office on Dubois campus, discrete office hours (now that I have an office at Penn State Dubois) and the elimination of my cell phone number (I did have students text me questions instead of email me). Therefore, on my latest syllabus, I indicated that email is my preferred method of communication.
At the beginning of this semester, I chose to eliminate last year’s objectives because they were poorly written and include a course overview instead. On my latest syllabus, I have rephrased the course overview and reinforced the major objectives of my course. I believe that the focus and direction of the course is clearer not only to myself but my students as well. Additionally, I have several updated policies:
1. Attendance - This year I added attendance to the grading scheme in hopes that students might be less inclined to schedule meetings with other professors or interviews during my class. While I understand that life happens, it is discouraging to see the lack of value students put on my class. After a discussion with Dr. Cindy Raynak, she suggested changing “Attendance” to “Participation”. My initial policy indicated as long as students were physically in a chair, they would receive a point and students will do anything for a point. To encourage more participation, I should call it just that.
2. Cell phones and Other Electronics - Last year I did not even think to have this policy, but it quickly became clear that I needed one. I struggled with the language I wanted to use, but I needed students to see how serious I am about the policy.
3. Examinations - Somehow I missed including this policy in 2015 and at the beginning of 2016. However, I wrote a short statement to cover the single exam I have in this course. It was difficult to find examples of this policy online as a basis for my own. However, I think this covers what I need.
4. Formatting - Last year I received a barrage of formats for writing assignments. This year, I included a policy for consistency as well as a sense of professionalism.
5. Late Assignments - Last year I did not have a late assignment policy which came back to bite me. Therefore, I was sure to include it this year. This policy was based off of a policy from an instructor who I respect and whose teaching style I try to incorporate into my own.
Another change that I made, per the suggestion of Dr. Raynak, is putting my “Grading” and “Points” sections together. This way, students have all of the information they need in once place. In addition, Dr. Raynak suggested including the point values for the ranges of each grade. This way, students do not have to do the math to see what grade they are getting. Her point was that students should work on the course materials instead of working on the syllabus to see what grade they will receive. With some thought, I finally agreed with this scenario and added the point values under “Grading”.
Another change that I made this year was related to the “Course Schedule” section of the syllabus. The change I decided to make was to include the Taking Sides Topics in the syllabus instead of another document as I did last year. Students had to use too many resources to figure out what chapter they were to read for class. Additionally, I included the corresponding chapters to help alleviate confusion.
Overall, I have become much more confident with my syllabus and my course as a whole. Being able to clearly communicate my goals and expectations to the class will help their performance as well as enhance my overall delivery of the course.
Thursday, May 23, 2013
Taking Their Breaths Away
I think one of the reasons I like damselflies and their larvae is because they look neat! The adults are so fragile, even more so than dragonflies, and the larvae have three beautiful “tails”, also known as caudal lamellae. In the summer of 2011, I was working in a fisheries lab and we were told to design individual projects. I got the crazy idea that I could raise damselflies, take pictures of them every week, and when they emerged, identify them to species and use the pictures to make a species key for larval damselflies. Little did I know that when I would go to identify my first emerged adult I would stumble across a larval key, get very upset that my project was useless and resign to the fact that raising macroinvertebrates was just too difficult a task for me anyways. The point of this anecdote was that when I originally collected the live damselfly larvae some of them lost their “tails” and I figured they would die within the first week. I knew that their three caudal lamellae were a source for respiration and would probably be able to live with out one, but not two. After stumbling across the following paper, I have reevaluated the main cause of death for may of the larvae to be their lack of interest in the fish food/mosquito larvae diet they were on, not that their gills had fallen off.
The following paper is entitled “Hypoxia and lost gills: Respiratory ecology of a temperate larval damselfly” by Sesterhenn, Reardon, and Chapman. The authors examined the effect of hypoxia (low dissolved oxygen) on the behaviors of an Ischnura (Coenagrionidae) species with respect to the number of caudal lamellae. This is important to understand as many lakes and slow moving systems, the favored habitat of most damselfly species, become eutrophic. Damselfly and dragonfly species are the top predator of aquatic macroinvertebrates in fishless systems and this role in an ecosystem with low dissolved oxygen is one reason that makes them a model organism for a study on hypoxia.
Caudal lamellae have many uses other than their function for respiration. They are also used for ion regulation, locomotion, intraspecific signaling, and weaponry. However, they are most well adapted for the uptake of oxygen. In looking at a close-up picture you will find that they look like a leaf with prominent veins. It is estimated that up to 90% of individuals in a population may lose at least one lamellae in its life just through the harshness of an environment. However, damselflies have other ways of breathing or increasing oxygen intake. One method is through rectal pumping which allows water to move in and out of the organisms back end and absorbing oxygen through specialized cells inside of the organism. Another method is abdomen waves in which the damselfly will “swish” its abdomen side to side to move water across its lamellae. Also, some damselflies (actually, most gilled aquatic macroinvertebrates use these methods) will do “pull-downs” or what I think looks more like a push-up. This also helps move water over the gills. Below is a link for a stonefly doing this action. Lastly, aquatic macroinvertebrates may just move to the surface of the water to access the oxygen rich layer right below the surface. Despite these other methods, the researchers hypothesized that the “number of caudal lamellae influences damselfly respiratory ecology, and that the role of lamellae may change at different levels of dissolved oxygen.”
With all of this in mind, Ischnura larvae were collected from low dissolved oxygen ponds in Kentucky. Only specimens with all three lamellae were taken for this experiment. The researchers successfully kept them alive (their methods for that make sense in retrospect as compared to mine) and prepared the larvae for two types of experiments. The first experiment involved measuring metabolic rates of damselfly larvae with either three or one caudal lamellae (yes, that means they pulled two lamellae off of some specimens). Through a complex set-up, the oxygen decline in a closed system in response to damselfly respiration could be measured. The second experiment was to observe behaviors of three and one lamellae damselflies at various levels of dissolved oxygen. Behaviors were recorded with a video camera.
What they learned from all of this is that the metabolic rate of Ischnura larvae was not affected by the number of lamellae. Also, smaller individuals and those with one lamellae spent more time near the surface of the water when the dissolved oxygen was low in the behavioral experiments. In addition, the alternate behaviors I previously described were observed more as the dissolved oxygen level decreased. From this we can understand that Ischnura is well adapted to living in low dissolved oxygen (hypoxic) ecosystems. It can also be noted that one caudal lamellae is sufficient for survival. The loss of all three lamellae would change the larvae’s ability to swim and then it wouldn’t be able to move oxygenated water over its body if needed. Therefore, the loss of all three lamellae is much more lethal.
Knowledge about specific tolerances of macroinvertebrates of environmental conditions will prove to be critical as water systems are degraded. A loss of macroinvertebrates communities will hurt fish populations if the fish aren’t directly affected by the low dissolved oxygen in the first place. It also goes beyond dissolved oxygen. Specific chemical tolerance can be species specific which also makes it that more important to know what is going into our waterways (*cough cough* fracking fluid)!
Stonefly pushups:https://www.youtube.com/watch?v=c06Up7YGkY4
Link to original paper:http://www.sciencedirect.com/science/article/pii/S0022191012002752
More about respiration and caudal lamellae: http://link.springer.com/content/pdf/10.1007%2FBF00323773.pdf
Ischnura being parasitized by mites!:http://www.researchgate.net/publication/232664446_PARASITISM_OF_ISCHNURA_POSITA_%28ODONATA_COENAGRIONIDAE%29_IN_FLORIDA_BY_TWO_SPECIES_OF_WATER_MITES
The following paper is entitled “Hypoxia and lost gills: Respiratory ecology of a temperate larval damselfly” by Sesterhenn, Reardon, and Chapman. The authors examined the effect of hypoxia (low dissolved oxygen) on the behaviors of an Ischnura (Coenagrionidae) species with respect to the number of caudal lamellae. This is important to understand as many lakes and slow moving systems, the favored habitat of most damselfly species, become eutrophic. Damselfly and dragonfly species are the top predator of aquatic macroinvertebrates in fishless systems and this role in an ecosystem with low dissolved oxygen is one reason that makes them a model organism for a study on hypoxia.
Caudal lamellae have many uses other than their function for respiration. They are also used for ion regulation, locomotion, intraspecific signaling, and weaponry. However, they are most well adapted for the uptake of oxygen. In looking at a close-up picture you will find that they look like a leaf with prominent veins. It is estimated that up to 90% of individuals in a population may lose at least one lamellae in its life just through the harshness of an environment. However, damselflies have other ways of breathing or increasing oxygen intake. One method is through rectal pumping which allows water to move in and out of the organisms back end and absorbing oxygen through specialized cells inside of the organism. Another method is abdomen waves in which the damselfly will “swish” its abdomen side to side to move water across its lamellae. Also, some damselflies (actually, most gilled aquatic macroinvertebrates use these methods) will do “pull-downs” or what I think looks more like a push-up. This also helps move water over the gills. Below is a link for a stonefly doing this action. Lastly, aquatic macroinvertebrates may just move to the surface of the water to access the oxygen rich layer right below the surface. Despite these other methods, the researchers hypothesized that the “number of caudal lamellae influences damselfly respiratory ecology, and that the role of lamellae may change at different levels of dissolved oxygen.”
With all of this in mind, Ischnura larvae were collected from low dissolved oxygen ponds in Kentucky. Only specimens with all three lamellae were taken for this experiment. The researchers successfully kept them alive (their methods for that make sense in retrospect as compared to mine) and prepared the larvae for two types of experiments. The first experiment involved measuring metabolic rates of damselfly larvae with either three or one caudal lamellae (yes, that means they pulled two lamellae off of some specimens). Through a complex set-up, the oxygen decline in a closed system in response to damselfly respiration could be measured. The second experiment was to observe behaviors of three and one lamellae damselflies at various levels of dissolved oxygen. Behaviors were recorded with a video camera.
What they learned from all of this is that the metabolic rate of Ischnura larvae was not affected by the number of lamellae. Also, smaller individuals and those with one lamellae spent more time near the surface of the water when the dissolved oxygen was low in the behavioral experiments. In addition, the alternate behaviors I previously described were observed more as the dissolved oxygen level decreased. From this we can understand that Ischnura is well adapted to living in low dissolved oxygen (hypoxic) ecosystems. It can also be noted that one caudal lamellae is sufficient for survival. The loss of all three lamellae would change the larvae’s ability to swim and then it wouldn’t be able to move oxygenated water over its body if needed. Therefore, the loss of all three lamellae is much more lethal.
Knowledge about specific tolerances of macroinvertebrates of environmental conditions will prove to be critical as water systems are degraded. A loss of macroinvertebrates communities will hurt fish populations if the fish aren’t directly affected by the low dissolved oxygen in the first place. It also goes beyond dissolved oxygen. Specific chemical tolerance can be species specific which also makes it that more important to know what is going into our waterways (*cough cough* fracking fluid)!
Stonefly pushups:https://www.youtube.com/watch?v=c06Up7YGkY4
Link to original paper:http://www.sciencedirect.com/science/article/pii/S0022191012002752
More about respiration and caudal lamellae: http://link.springer.com/content/pdf/10.1007%2FBF00323773.pdf
Ischnura being parasitized by mites!:http://www.researchgate.net/publication/232664446_PARASITISM_OF_ISCHNURA_POSITA_%28ODONATA_COENAGRIONIDAE%29_IN_FLORIDA_BY_TWO_SPECIES_OF_WATER_MITES
Sunday, May 19, 2013
Kick, kick! Who's in There?
Aquatic macroinvertebrates are critical species to understand when conducting biological surveys of aquatic ecosystems. Many times, population changes over long term monitoring schemes serve as indicators of water quality. Typically, samples are collected with a kicknet. I follow Frost and Huni’s procedures outlined in their 1971 paper. The authors say that their method effectively collects 90% of the benthic (bottom-dwelling) fauna. Samples are preserved in 70% ethanol and taken back to the laboratory for identification. Aquatic macroinvertebrates are usually identified to the lowest taxonomic unit possible, which in many cases is the genus level identification. Species keys are not developed for most larvae because of the morphological (physical) differences in instars (stages of development). If individuals in a sample are damaged, identification to the genus level may not be possible. In addition, there is room for human error in the identification process.
Therefore, there may be a need for other methods of identifying the specimens in a field collection of aquatic macroinvertebrates. One way of doing this is using Next-generation sequencing (NGS). NGS is a new technology that is starting to be applied to the biological sciences. NGS is similar to other DNA sequencing technologies; however, NGS is able to analyze mixtures of DNA. Therefore, the theory is that biologists can collect aquatic macroinvertebrates in the same manner they have in the past, but can analyze a mixture of DNA to get species level identification. DNA can be sequenced from one of three ways although only two are ideal. The first method is to blend the entire sample and analyze the smoothie of aquatic macroinvertebrates. However, this is the least ideal method because it is quite destructive. The other two methods allow the specimens to have minimal damage done to them. One method is for researcher to take a tissue sample from each individual specimen (usually a leg but not all macro invertebrates have those) and add that to the blend of DNA. The second, and least destructive, method is to use the ethanol the aquatic macroinvertebrates have been preserved in; as specimens sit in ethanol, some of their DNA ends up in the liquid ethanol. This is called “free DNA”.
Without getting too technical, the DNA is amplified (copies are made through chemical processes) and sequenced (think of each DNA strand having its own barcode) and then matched against known sequences (barcodes in a library). These known sequences are species specific. This sounds great; however, there are several biases that may prove to be problematic for at least the near future. The greatest issue is that some strands of DNA may get copied more than others and therefore the abundance of individual species will be skewed. Remember that biomonitoring tends of look at changes in populations over time so if there is no accurate indication of population size, this information may be useless. In addition, it may obscure the presence of some species. Also, this bias makes DNA copying not replicable since there is no consistency in which strands will be amplified more than others. There have been attempts to avoid this bias by using different types of amplifiers (copiers) and different combinations of DNA sources. The highest detection rate has been 91.3% in a combined “free DNA” and tissue DNAs along with multiple types of amplifiers.
It should be noted that this is different than eDNA (environmental DNA), which would involve testing pieces of the environment for traces of DNA. An example, and increasing application of eDNA technology, would be taking a water sample and testing for the DNA of invasive fishes to test for presence/absence data. For NGS it is required to have a collected and preserved specimen.
This type of technology could be applied to the monitoring of terrestrial invertebrates such as a collection from a malaise trap. However, the same biases still apply. NGS technology needs to be refined, and if easy to use, I would be happy to try using it in the monitoring programs I am involved in.
This article this post is based on can be found at: http://www.biomedcentral.com/content/pdf/1472-6785-12-28.pdf
Therefore, there may be a need for other methods of identifying the specimens in a field collection of aquatic macroinvertebrates. One way of doing this is using Next-generation sequencing (NGS). NGS is a new technology that is starting to be applied to the biological sciences. NGS is similar to other DNA sequencing technologies; however, NGS is able to analyze mixtures of DNA. Therefore, the theory is that biologists can collect aquatic macroinvertebrates in the same manner they have in the past, but can analyze a mixture of DNA to get species level identification. DNA can be sequenced from one of three ways although only two are ideal. The first method is to blend the entire sample and analyze the smoothie of aquatic macroinvertebrates. However, this is the least ideal method because it is quite destructive. The other two methods allow the specimens to have minimal damage done to them. One method is for researcher to take a tissue sample from each individual specimen (usually a leg but not all macro invertebrates have those) and add that to the blend of DNA. The second, and least destructive, method is to use the ethanol the aquatic macroinvertebrates have been preserved in; as specimens sit in ethanol, some of their DNA ends up in the liquid ethanol. This is called “free DNA”.
Without getting too technical, the DNA is amplified (copies are made through chemical processes) and sequenced (think of each DNA strand having its own barcode) and then matched against known sequences (barcodes in a library). These known sequences are species specific. This sounds great; however, there are several biases that may prove to be problematic for at least the near future. The greatest issue is that some strands of DNA may get copied more than others and therefore the abundance of individual species will be skewed. Remember that biomonitoring tends of look at changes in populations over time so if there is no accurate indication of population size, this information may be useless. In addition, it may obscure the presence of some species. Also, this bias makes DNA copying not replicable since there is no consistency in which strands will be amplified more than others. There have been attempts to avoid this bias by using different types of amplifiers (copiers) and different combinations of DNA sources. The highest detection rate has been 91.3% in a combined “free DNA” and tissue DNAs along with multiple types of amplifiers.
It should be noted that this is different than eDNA (environmental DNA), which would involve testing pieces of the environment for traces of DNA. An example, and increasing application of eDNA technology, would be taking a water sample and testing for the DNA of invasive fishes to test for presence/absence data. For NGS it is required to have a collected and preserved specimen.
This type of technology could be applied to the monitoring of terrestrial invertebrates such as a collection from a malaise trap. However, the same biases still apply. NGS technology needs to be refined, and if easy to use, I would be happy to try using it in the monitoring programs I am involved in.
This article this post is based on can be found at: http://www.biomedcentral.com/content/pdf/1472-6785-12-28.pdf
Thursday, May 9, 2013
Looking at the Little Guys
Insect behavior is a curious thing. Those that are terrestrial are easily observed by the average person such as ants on the ground, bees buzzing around flowers, crickets chirping at night or the pesky house fly sitting on the window. However, there are many insects whose behaviors go unnoticed. One such group of insects is a group that lives in water also referred to as aquatic macroinvertebrates.
Aquatic macroinvertebrates exhibit a behavior called drift. A scientist by the name of Mueller (no known relation but I am looking into it) described a phenomenon where some, not all, species of macroinvertebrates release themselves from the substrate and float downstream in the current until they choose to grab ahold again. The macroinvertebrates continue this process of moving farther and farther downstream until they emerge and the adult fly upstream to lay their eggs. Once the eggs hatch the process of drifting repeats itself. Without going into further detail of when, why, types and other patterns, simply put there is still limited knowledge about this behavior.
An increasing number of studies have been done to look at various factors influencing insect drift. One particular study looked at the impact of suspended solids (sediment) on macroinvertebrates drift behavior in an Indiana Creek (USA). Sediment is considered a pollutant, which comes from activities such as mining, farming, and logging. Previous studies have shown that when there has been an observed increase in sediment in water there has been an observed decrease in macroinvertebrate numbers because sediment decreases the amount of light that comes through the water column as well as smothers habitat. This particular study wanted to consider the impact of sediment runoff of a rock quarry. In this study, controlled amounts of sediment (collected from the bottom of the quarry’s settling ponds) were released into the stream from a modified garbage can dispenser. Holes in the bottom of the can allowed water to flow through the garbage can and a known amount of sediment was placed inside therefore they could calculate the total suspended solids released.
Collecting drifting macroinvertebrates is done by using an appropriately named drift net. These nets were placed in the water downstream of the garbage can for 15 minutes during the time the sediment was being added. After 15 minutes, nets were removed from the water and the insects and debris captured were preserved in 70% ethanol. In the laboratory, macroinvertebrates were identified and counted. Water samples were also taken to be checked in the laboratory for the total suspended solids in order to compare the numbers to what was being released. The researchers were responsible and stopped the experiment on a particular day when they noticed sediment starting to collect on rocks in the study site. Lastly, a substrate sample was also taken, on non-experiment days, with a Surber sampler to determine what the natural benthic macroinvertebrate community structure was.
The results of this study were not particularly surprising. There was a linear relationship between the number of macroinvertebrates drifting and the amount of sediment put into the stream. They found that midge, blackfly, caddisfly, and mayfly larvae were the most common drifting species. Riffle beetles were observed in the substrate but did drift and were therefore not as effected by the sediment entering the water. The researchers cannot be sure, but they believe this drifting behavior could be classified as active-behavioral drift. This means that the macroinvertebrates chose to move away from something happening in their environment as opposed to being carried away by a high flow after a heavy rain. Based on their observations, short term re-population of the study area was successful but high levels of suspended solids could be detrimental in the long term.
So even though an impact like dumping sediment into a stream is a pretty drastic situation, it can have further implications on an ecosystem than just making some insects change habitat. Fish rely on macroinvertebrates as a food source. No macroinvertebrates will mean no fish. Therefore, it is critical that more studies like this one occur to find our what human activities have what level of effect on macroinvertebrate behaviors. The same applies for the dumping of chemicals or excess water into streams. What are the part per million or part per billion tolerances of macroinvertebrates? How tightly can they hang onto the substrate when there is an increased flow? There is also limited knowledge of the time scales of which these changes in macroinvertebrate behaviors occur. Therefore, as more an more industry waste is created it is important to remember the little guys even if we don't see them every day.
To see the original paper visit: https://journals.iupui.edu/index.php/ias/article/viewFile/8310/8461
To read more about the original research on drift, locate the paper:
Müller, K. 1954. Investigations on the organic drift in North Swedish streams. Rep. Inst. Freshw. Res. Drottning. 35:133-148.
Aquatic macroinvertebrates exhibit a behavior called drift. A scientist by the name of Mueller (no known relation but I am looking into it) described a phenomenon where some, not all, species of macroinvertebrates release themselves from the substrate and float downstream in the current until they choose to grab ahold again. The macroinvertebrates continue this process of moving farther and farther downstream until they emerge and the adult fly upstream to lay their eggs. Once the eggs hatch the process of drifting repeats itself. Without going into further detail of when, why, types and other patterns, simply put there is still limited knowledge about this behavior.
An increasing number of studies have been done to look at various factors influencing insect drift. One particular study looked at the impact of suspended solids (sediment) on macroinvertebrates drift behavior in an Indiana Creek (USA). Sediment is considered a pollutant, which comes from activities such as mining, farming, and logging. Previous studies have shown that when there has been an observed increase in sediment in water there has been an observed decrease in macroinvertebrate numbers because sediment decreases the amount of light that comes through the water column as well as smothers habitat. This particular study wanted to consider the impact of sediment runoff of a rock quarry. In this study, controlled amounts of sediment (collected from the bottom of the quarry’s settling ponds) were released into the stream from a modified garbage can dispenser. Holes in the bottom of the can allowed water to flow through the garbage can and a known amount of sediment was placed inside therefore they could calculate the total suspended solids released.
Collecting drifting macroinvertebrates is done by using an appropriately named drift net. These nets were placed in the water downstream of the garbage can for 15 minutes during the time the sediment was being added. After 15 minutes, nets were removed from the water and the insects and debris captured were preserved in 70% ethanol. In the laboratory, macroinvertebrates were identified and counted. Water samples were also taken to be checked in the laboratory for the total suspended solids in order to compare the numbers to what was being released. The researchers were responsible and stopped the experiment on a particular day when they noticed sediment starting to collect on rocks in the study site. Lastly, a substrate sample was also taken, on non-experiment days, with a Surber sampler to determine what the natural benthic macroinvertebrate community structure was.
The results of this study were not particularly surprising. There was a linear relationship between the number of macroinvertebrates drifting and the amount of sediment put into the stream. They found that midge, blackfly, caddisfly, and mayfly larvae were the most common drifting species. Riffle beetles were observed in the substrate but did drift and were therefore not as effected by the sediment entering the water. The researchers cannot be sure, but they believe this drifting behavior could be classified as active-behavioral drift. This means that the macroinvertebrates chose to move away from something happening in their environment as opposed to being carried away by a high flow after a heavy rain. Based on their observations, short term re-population of the study area was successful but high levels of suspended solids could be detrimental in the long term.
So even though an impact like dumping sediment into a stream is a pretty drastic situation, it can have further implications on an ecosystem than just making some insects change habitat. Fish rely on macroinvertebrates as a food source. No macroinvertebrates will mean no fish. Therefore, it is critical that more studies like this one occur to find our what human activities have what level of effect on macroinvertebrate behaviors. The same applies for the dumping of chemicals or excess water into streams. What are the part per million or part per billion tolerances of macroinvertebrates? How tightly can they hang onto the substrate when there is an increased flow? There is also limited knowledge of the time scales of which these changes in macroinvertebrate behaviors occur. Therefore, as more an more industry waste is created it is important to remember the little guys even if we don't see them every day.
To see the original paper visit: https://journals.iupui.edu/index.php/ias/article/viewFile/8310/8461
To read more about the original research on drift, locate the paper:
Müller, K. 1954. Investigations on the organic drift in North Swedish streams. Rep. Inst. Freshw. Res. Drottning. 35:133-148.
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