kheredia's blog

Our final project for Writing in biology fall 2019 was chosen to be: Lichen as bioindicators of air pollution in Amherst, Massachusetts
Lichens can be used as bioindicators of airborne pollution either via morphological changes based on pollutant accumulation or by the diversity of lichens in an area. Measures of air pollution using lichens as bioindicators have yet to be done in Amherst, Massachusetts. We aim to compare air pollution levels in Amherst by comparing the number of lichen species in 4 x 4 m plots around two spots on the University of Massachusetts, Amherst campus: the more urbanised Campus Pond and the less urbanised Sylvan woods.

Materials:
2 measuring tapes, plastic flags, a clipboard with a piece of paper, a pencil, a compass and a metal grid and push pins.
2 predetermined locations near campus where lichen was found: Sylvan and campus pond
We used photos of specific lichen to aid in identification: Crustose, foliose, fruticose

Methods:
We marked a 4x4 meter plot of trees in the less urbanized sylvan area and the more urbanized campus pond. We estimated the plots with 4 plastic flags and a meter measuring tape. Once plotted, we used the 100 metal grid plot and recorded the amount of lichen species present on the north-facing side of included trees, 1 meter up from the bottom of the trees. We used a push pin as a placeholder for the 1 meter mark, and recorded the number of species on the clipboard for each trial with the grid until we reached the top of the meter.

The presence of artificial light in particular, during the dark sequence of the biological rhythm, has suggested a negative relationship between exposure of light and effect on our sensory input, which in turn, directly affects behavior. In diurnal vertebrates such as human beings, constant illumination throughout sleep, (the least physically active time of the 24 hour cycle) inhibits the production of melatonin, potentially leading to cognitive dysfunction and behavioral changes due to stress, and ultimately anxiety from failure to reorient to the change in the environment.

This information posed the pressing question of whether organisms on the opposite side of the spectrum, nocturnal invertebrates, are also disturbed by the essence of light during the evening: where they are most active. Increasing evidence suggests that they are, specifically in crickets, where levels of overall activity decreased with lifetime subjection to light pollution. For this reason, house crickets, or Acheta domesticus, were the focal point of this study, with the objective to continue analysis on whether artificial light during the dark cycle affects activity, this time in shorter periods, to test the frequency of mating behaviors.

Artificial light, or light pollution, is a major topic of concern for a variety of species, especially those who are nocturnal, and spend most of their time in the dark. As earth becomes more and more populated by humans, many things are changing, including habitats, ecosystems, and overall activity of so many animals. A key physiological process found in many animals, humans, and even plants that can be affected by changes in light, is the circadian rhythm. Circadian rhythms are the internal clocks that regulate both physiological and behavioral responses to the environment. Productivity in both humans and animal is heavily influenced by these rhythms, and sort of disruption of rhythm, say, from artificial light, could affect an animal’s ability to function, which would have negative impacts on behavior (Moore-Ede et al.,1982).

Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID). It works by reducing hormones that cause inflammation and pain in the body. One of these hormones, prostaglandin, is inhibited when taking the medication. The synthesis of prostaglandin results in dilation of afferent arterioles. Because ibuprofen inhibits the formation of prostaglandin, our afferent arteriole’s begin to constrict without a signal to dilate due to the absence of the hormone. As a result, there is a decrease of blood flow in the kidney and therefore filtration is also reduced.

When we exercise, our vessels constrict in the kidney and slow down blood flow so that our bodies can focus more pumping blood to the muscles as we are using them when we exercise. From the information just learned, taking ibuprofen for a cramp during physical exercise would only have negative effects on the body. This would increase stress on the kidney inducing further constriction and reduced blood flow to the arterioles.

Ibuprofen inhibits prostaglandin formation. Prostaglandin dilates afferent arterioles. Since ibuprofen inhibits prostaglandin, our afferent arteriole can no longer be as dilated as it was before, which will decrease blood flow in the kidney and therefore filtration. When we exercise, we constrict vessels in the kidney and slow down blood flow in order to focus more on the muscles we are using when we exercise. We would definitely not want to take ibuprofen while exercising, as this would stress our kidney out even more and would cause more constriction and reduced blood flow to the arterioles supplying blood for the kidney.

Hyperventilation happens when PCO2 drops. When PCO2 drops, we become more basic, and pH increases. This means we are alkaline, and that translates to us having respiratory alkalosis. An example of this happening is when we are at high altitude. When we are hypoventilating, we’re breathing too little. We have increased PCO2, and this lowers pH, and makes us more acidic. Therefore, we have respiratory acidosis.

Other pH imbalances include metabolic acidosis, where the production of blood acids exceeds loss. Examples of this include ketoacidosis, diarrhea and intense exercise. On the other hand, metabolic alkalosis is when the production of blood acids is less than loss. An example of this is throwing up.

Hypothesis: Light will disrupt courting activity in male crickets, causing them to exhibit fewer mating/competitive behaviors when in the presence of a female cricket and another male cricket.

We chose this hypothesis because when we were working on crickets for lab a few weeks ago, we noticed that the crickets were looking to hide under the paper provided inside of their tanks, and this sparked the question of whether their activity slows down based on how much light is available to them. We know that Light pollution is a big problem, so we wondered how it will affect mating behavior in an animal that we know normally mates at night, and found that their activity is decreased in a study done on crickets being exposed to longterm light conditions.

In another study, on the circadian rhythms of crickets, it was found that they are entrained to be active during the “dark period” which further supports our hypothesis that light disrupts their activity. Our goal is to observe whether males are more active, i.e. displaying behaviors of competition towards another male, or courting a female, in light or dark conditions, and determine of exposure light is the cause of this- which is why we are also including a reference describing types of courtship behaviors in male, in particular, chirping.

We are also referencing our lab we did in class a few weeks ago, where we observed aggressive territorial behaviors in winner versus losers in crickets, as a source of what kinds of behaviors males display when they are competing with another male. Finally, our last reference helps us to better understand when crickets begin mating calls. The reference explains the variances in times and intensity for male mating calls during the evening, which helps our hypothesis further by demonstrating that the light presented in one of the tanks during our experiment will disrupt the courting activity and deter males from calling for females.

After sexing all thirty crickets and separating them accordingly, observers waited 5 minutes to allow the crickets to settle into their new containers. After the 5 minutes ended, two females were chosen at random to be placed into the light and dark simulation arenas. The female crickets were alone in the arenas for 3 minutes before 4 males were chosen at random (two for each arena) and placed simultaneously into the respective arenas. Once all 3 crickets were in an observation tank together, they were watched for a total of 5 minutes.

One observer attended to the trio in the light arena, while the other examined the trio in the dark arena. During this time, observers kept a tally of any mating behaviors or aggressive/competitive behaviors. This includes pursuing the female to mate, or engaging in male-male competition. Examples of female persuasion behavior included actively following the female, mounting, or chirping. Examples of male-male competitive behaviors included moving pinchers, actively moving towards the other male in the arena, and also chirping. If either male began to pursue the female within the allotted time period, the time of first movement towards the female was also written down. After the observation time was completed, all three crickets from each tank were placed back into their original holding container to eliminate re-using a cricket in the same arena and to assure trials were completed independently of one another. This procedure was repeated 5 times for each type of environment.

The following equipment was used to ensure proper handling of subjects and simulate a light or dark environment. Two containers were used as vessels to house both sexes of crickets, respectively. Holes were poked into the lids of the containers to ensure proper ventilation for the insects. Two larger containers were used as arenas, where the majority of the experiment was conducted. In the first large container, used as the light environment simulation, a lamp of 5 watts was placed directly overhead. This angle of the lamp was to help mimic the brightness of the sun at noon.

The second large container, simulating the dark environment, had only minimal, ambient light from the window. The low, natural light was necessary for the observers to assess latin name cricket. Two vials were used to safely transfer the crickets from their housing containers to the light and dark arenas, in which they could be properly observed.