Results, Revisions, and Revamping

7 11 2012

Recap: So I set up the experiments, collected the samples, counted all of the different sized particles, and entered them into a spreadsheet.  Now what?

An example of R code I used to generate a figure (B. Blaud)


I have a secret… I hate R.  Ok, I don’t mean that; I just don’t like it as much as I should, as a scientist.  R  is an amazing free data analysis tool that you can do anything on, as long as you speak computer (specifically, S Language).  I, unfortunately, don’t.  Learning to speak computer is like learning a whole new language, which takes time, dedication, and motivation to practice.  To learn a language, you sing the alphabet song, study vocabulary on flashcards, and practice grammar by writing meaningless sentences in four different tenses over and over.  Learning a computer language is similar, and so I cheat.  I use Excel.  Instead of fourteen lines of code that may be necessary to generate a figure of the average volume of particles in each run, I just hi-lite the desired cells, and type “=AVERAGE(B2:B115)” to compute my run average, and fill in the blanks under the “Charts” tab to make a pretty picture.


Why is this a dirty secret?  Several great blogs and articles out there explain in great detail the difference between the two types of software, mainly focusing on user-friendliness and statistical power.  Overall, though, in the professional world, it’s frowned upon to use something like Excel.  So for now, in a very public blog that I share with everyone I know and a lot of people I don’t know, I will just ask that you keep my secret until I become more proficient in the more professional software – which I am working on, slowly but surely. 

This is from my PowerPoint presentation on my project showing figures generated on Excel.  The legend in the top right shows how the colors of the bars change with the increase in probability of successful fertilization in sperm concentration. (B. Blaud)

Now, I get back to the actual results.  It was incredibly exciting counting egg sized particles.  I was finding them in samples as far as 8m away from where they were released, yet they were still hanging out at each distance as long as 5 minutes after the initial release.  Pretty cool!  This means that in the turbulent intertidal, where water is constantly coming and going, the eggs still remain in the immediate area, but just disperse more depending on how the strength of the water activity.

Abalone egg


The sperm sized particles were what I was initially more invested in, seeing as how it’s the guys that really get the girls going, and it’s the concentration of sperm that determine fertilization success.  You see, for an egg to be fertilized, there just needs to be at least one egg present, but it requires 10,000 to 1,000,000 sperm per milliliter (mL) of seawater for a 60 to 100% probability of fertilization (according to laboratory studies).  Fertilization can occur with as few as 100 to 1,000 sperm/mL of seawater, but the probability drops below 10%.  In my results, the concentrations of sperm rarely went above 500 sperm/mL, and only twice were above 1,000 sperm/mL.


At first, I was disheartened by these results, thinking this means that my experiment failed or spawning success was extremely unlikely in the intertidal.  After putting this into more realistic terms, however, I realized that my experiment only represents a single male spawning for a period of 10-minutes, whereas actual spawning events may take as long as an hour, and gametes continue to remain viable (alive and able to fertilize) for an additional hour after being spawned.


So I revised my project.  Instead of a single male spawning for 10 minutes, I’m going to compare results from a single male spawning for 30 minutes (with samples collected 30 minutes after spawning commences) with three simultaneous males spawning for 10 minutes, and see how those results differ from my original experimental runs.  And in the future, I will avoid coulter counters at all costs!!!  (That’s the revamp).



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