Tuesday, June 26, 2012

Can you spot the predator?


I'll give you a hint: the predator in question is an arthropod, but not an insect.

If you can't spot it, don't be too hard on yourself... neither could the ant in the center of this blanketflower.

The predator I refer to is a spider from the family Thomisidae, commonly referred to as 'crab spiders'. (If you still haven't spotted it, the spider is on the left side of the central reddish disk). Most crab spiders, this one included, employ an ambush hunting strategy. They simply sit tight on or beside a flower and wait for insects to come to them.

Our predator should be more obvious in this one....

Sunday, May 27, 2012

Truth in advertising: Dove's "Followers" video

I came across this ad by Dove while watching an episode of The Office.


The video, which is part of the Dove Movement for Self-Esteem, lists the number of Twitter followers (as of March 8, 2012) associated with "Today's top female..."
Reality Star -- 4,553,457
Fashion Model -- 13,710,211
Pop Star -- 20,268,261
Scientist -- 7
and concludes with the message
Dove wants to introduce your daughter to some new role models. Because strong female role models build stronger self-esteem.
Alright, it's a clever video and improving self-esteem is a worthwhile goal. But 7! Today's top female scientist has only 7 followers on Twitter? I don't know about you, but reading that statistic set off like all of my bullshit detectors. Of course, I don't doubt that scientists (regardless of gender) generally have far fewer Twitter followers than reality stars, models, and pop stars. I just don't think the difference is quite that large.

Initially, I figured it would be easy to disprove the '7 followers' statistic, but then something occurred to me... who the hell is "today's top female scientist"? The word 'top' is both ambiguous and subjective. Identifying "today's top female scientist" is kind of like identifying "the world's best city".

Given this ambiguity, there is really no way to test the claims made in Dove's video (well played, Dove). Nonetheless, I think if we can find some prominent female scientists with a lot more than 7 Twitter followers, it will demonstrate that Dove's video is somewhat misleading.

Here's what Google turned up (note my search was haphazard and certainly not exhaustive):

Number of Twitter followers for select female research scientists:
Dr. Kate Clancy Anthropologist 3,093
Dr. Rachael Dunlop Medical Researcher 6,337
Dr. Chris Gunter Geneticist; Senior Editor for Nature (2002-2008) 4,706
Dr. Hopi Hoekstra Evolutionary Biologist 279
Dr. Karen James Geneticist; Director of Science, HMCS Beagle Project 7,044
Dr. Carolyn Porco Planetary Scientist; Leader of the Cassini Imaging Team 9,124
Dr. Lisa Randall Theoretical Physicist; Elected Member of the NAS 4,204
Dr. Jennifer Rohn Cell Biologist 3,366
Dr. Tara Smith Epidemiologist 3,334

Number of Twitter followers for select female science enthusiasts, journalists, etc.:
Dr. Deborah Berebichez Physicist; Science Communicator 6,573
Dr. Sylvia Earle Oceanographer; Nat Geo Explorer-In-Residence 7,090
Jane Goodall Institute Conservation Organization Founded by Jane Goodall 120,493
Maggie Koerth-Baker Science Editor for boingboing.net 8,506
Dr. Emily Lakdawalla Former Planetary Geologist; Science Writer 14,792
Joanne Manaster Biology Lecturer; Science Communicator 13,311
Jennifer Oullette Science Writer 5,638
Dr. Kirsten Sanford Former Neurophysiologist; Science Broadcaster 119,639
Nicole Stott Astronaut 94,045

Happily, the situation is not quite as gloomy as Dove's video would seem to imply. There are female research scientists with almost 10,000 Twitter followers and a few female science communicators with around 100,000 followers. Two scientists in particular, Drs. Carolyn Porco and Lisa Randall, probably are contenders for the title of "today's top scientist" and happen to have far more than 7 followers (to the tune of about 3 orders of magnitude). Drs. Porco and Randall have each co-authored more than 100 peer-reviewed publications and have received numerous awards, honours, and prizes in their respective fields.

So was Dove lying?

Not exactly, but they did use ambiguous language and data to exaggerate their claim. In all likelihood, the majority of today's 'top' scientists (regardless of gender and how one defines 'top') would have 0 (or more accurately, N/A) Twitter followers because relatively few scientists use Twitter (especially the most accomplished scientists who are generally a bit older). I spent about 45 minutes checking whether any female Nobel Laureates, Fellows of the Royal Society, or National Medal of Science recipients were on Twitter, but I couldn't find a single one (again, my search was not exhaustive). Of course, admitting that "today's top female scientist" doesn't use Twitter would have made for a much less effective, but probably more accurate, video.

Again, I don't doubt the general claim made in Dove's video. I'm simply a big fan of truth in advertising.

Saturday, May 26, 2012

What DO scientists look like?

This Is What A Scientist Looks Like is a really cool project aimed at myth-busting the traditional scientist stereotype. Here's a snippet from their website:
Have you ever searched the Internet for an image of a scientist? Of the first 20 images in a Google image search, only two are women, all are white, and most have either too much or too little hair. Oh and most are sporting spectacles ... 
[This Is What A Scientist Looks Like] is dedicated to changing the overwhelming stereotype that science is conducted behind closed doors by unapproachable old, white men.
The website features photographs of real scientists doing everyday things like dancing, surfing, playing with pets, rocking out on the guitar, posing with their wedding party, or pretending to be a walrus. It turns out that scientists are just as diverse and multidimensional as any other group of people, and they are even allowed to have fun!

Wednesday, May 23, 2012

0.999... = 1

Maybe this mathematical curiosity is more widely appreciated than I realize. However, I only recently became aware of it, so I will share with you the madness that I've discovered.

It turns out that 0.999... (the “...” means that the 9s go on forever) is equal to 1. And I don't just mean that the two numbers are extremely close to one another or that they are equal by convention. Rather, I'm telling you that the symbols 0.999... and 1 represent the exact same real number and that this equality can be proven.

If you're learning of this for the very first time, I can guess how you are feeling:


I was feeling the exact same way, and I knew what had to be done. Research mode engaged.

After about 20 minutes of intense research (e.g. Wikipedia, various math blogs, etc.), I was entirely satisfied that 0.999… = 1.

Preliminaries

First off, Wikipedia has an entire page on 0.999… = 1. If that doesn’t settle the matter, then I don’t know what will.

Next stop WolframAlpha, a “computational knowledge engine” that knows pretty much everything. For example, WolframAlpha knows the estimated number of atoms in the sun (9 x 10^56), the average undergraduate tuition at Harvard ($33,700 US), the population of Bahrain in 1962 (161,000 people), and even the phase of the moon on the night that Leonardo da Vinci was born (waning crescent). WolframAlpha also knows that 0.999… is equal to 1.


Evidence

Of course, the above arguments are really only appeals to authority, not actual evidence. So let’s get down to business.

Hopefully we can all agree that
1/9 = 0.111…
If so, we can also agree that
9 * 1/9 = 9 * 0.111...
We’ve simply multiplied both sides of the equation by 9, so the equality still holds true.

If we now simplify both sides of the equation, we are left with
1 = 0.999…
Crazy, right?! Another way to think about this is to ask: is there any number that can fit between 0.999… and 1? If two numbers are truly different, then at least one other number should fit in between them. But nothing fits between 0.999... and 1. For example, if we subtract 0.999... from 1, we get
1 - 0.999... = 0.000...1
The “...” on the right side of the equation represents an infinite number of 0s, so the 1 at the end is irrelevant. Subtracting 0.999... from 1 leaves us with nothing – a big fat goose egg.

You might have guessed that this strange phenomenon is not limited to 0.999… and 1. For the same reasons described above
1.999... = 2
0.42999... = 0.43
99.999... = 100, etc.
In fact, every nonzero number that ends in an infinite number of 0s (e.g. 1 can also be written as 1.000…) has a counterpart that ends in an infinite number of 9s.

See here and here for more details on this mathemagical weirdness.

Monday, May 21, 2012

Jay Ingram on Canada's Experimental Lakes Area

I came across a great (and rather old) video today describing some of the research that has been done at Canada's Experimental Lakes Area.
There are some scientific experiments that are so big, they cannot be done in a lab. That is why a small corner of Northwestern Ontario has been set aside for the scientists with those big ideas. It is called the experimental lakes area. Fisheries and Oceans scientists are trying to replicate what happens on a much larger scale elsewhere, for example acidification of lakes or flooding of peat bogs and dry forest. Their findings are now used to help mitigate the environmental impact of projects such a hydro electric dams.
Unfortunately, in science as in life, all good things must come to an end... generally under a Conservative government :-P

Sunday, May 20, 2012

Phosphorus, detergent, and Canada's Experimental Lakes

ResearchBlogging.org
I'm angry at the people who decided that phosphate was growing algae. I'm not sure that I believe that.  –Sue Wright, Texas
Sue Wright, quoted above, was upset because in 2010, sixteen American states banned the sale of dishwashing detergent containing high levels of phosphorus, an aquatic pollutant that sometimes causes eutrophication (algal blooms). Unfortunately, phosphorus is a rather effective component of detergent, so phosphorus-free dishwashing detergents did not immediately perform quite as well as their predecessors. This led some consumers (like our pal Sue) to complain to detergent manufacturers, state governments, consumer protection agencies, and the media.

What I like most about Sue’s complaint is that her anger was directed toward “the people who decided that phosphate was growing algae” rather than the policymakers who drafted and enacted the legislation. Her implied logic is exquisite – a factual claim has resulted in legislation that negatively affects some aspect of my life, therefore I don’t believe this factual claim and furthermore am angry at those who made it!

So, who specifically should Sue have directed her anger toward? Which jackass scientist “decided that phosphate was growing algae”?

The answer, unsurprisingly, is that many independent studies (involving various research groups) have demonstrated that phosphorus pollution, under some conditions, will stimulate algal growth and lead to eutrophication (see Schindler 2006 for a review). Here, I will focus on just one of these studies, perhaps the most influential.

My real motivation for discussing this particular paper is the recent announcement that the Canadian Government is discontinuing its operation of the Experimental Lakes Area (ELA), a collection of 58 pristine lakes that for over 40 years have been set aside for long-term ecosystem monitoring and ecosystem-scale experiments (more on the ELA later).

Green sludge

In the 1960s and 70s, many North American rivers and lakes, especially the Great Lakes, were experiencing rapid declines in water quality (see here and here). Industrial and municipal effluents were stimulating the growth of algae and other aquatic plants (termed ‘eutrophication’) leading to unsightly mats of green sludge, oxygen depletion, massive die-offs of fish and other aquatic life, and problems with the taste and odour of municipal drinking water.

The August 1969 issue of Time Magazine describes the then deteriorating state of Lake Erie:
Each day, Detroit, Cleveland and 120 other municipalities fill Erie with 1.5 billion gallons of inadequately treated wastes, including nitrates and phosphates. These chemicals act as fertilizer for growths of algae that suck oxygen from the lower depths and rise to the surface as odoriferous green scum. Commercial and game fish … have nearly vanished ... Weeds proliferate, turning water frontage into swamp. In short, Lake Erie is in danger of dying by suffocation.
The public, industry, and all levels of government agreed that something had to be done to curb the declining state of North American waterways. However, there was disagreement over the most effective course of regulatory action because at the time, scientists and policymakers were still debating which nutrients were responsible for eutrophication. Was algal growth primarily limited by carbon, nitrogen, or phosphorus?

Schindler 1974

Experiments are the best way to establish causation, but are not always feasible. For example, the best way to test the anthropogenic climate change hypothesis would be to release copious quantities of greenhouse gas into the atmospheres of a random sample of earth-like planets, leave another randomly-chosen bunch of planets untouched, and then compare change in climate across the two groups of planets. Clearly this is not feasible, and clearly we can’t experimentally pollute a bunch of lakes just for the sake of science. Right? Wrong. Well, wrong to the second assertion at least.

The aforementioned Experimental Lakes Area is (was) a wonderful place where scientists could manipulate whole lakes to test hypotheses on the scale of entire ecosystems. In the late 1960s and early 70s, David Schindler – a Canadian limnologist who at the time was director of the ELA – oversaw a number of whole-lake experiments designed to determine which nutrient (out of carbon, nitrogen, and phosphorus) was primarily responsible for eutrophication.

In an initial experiment, Schindler et al. added copious amounts of nitrogen and phosphorus to Lake 227 which naturally had an extremely low concentration of dissolved carbon. If algal growth was primarily limited by carbon (and not nitrogen or phosphorus), then the N + P treatment should not stimulate the growth of algae. However, this was not the case. Within weeks of the treatment, Schindler et al. observed that Lake 227 “was transformed into a teeming, green soup” with algal concentrations up to two orders of magnitude higher than nearby untreated lakes. Clearly, low levels of carbon had not been limiting the growth of algae.

In a second experiment, Schindler et al. divided another lake, Lake 226, into two equal halves using a large vinyl curtain that was sealed into the sediment and surrounding bedrock. The team added an equivalent amount of carbon and nitrogen to both halves of the lake, but added phosphorus to only one side. This manipulation resulted in what James Elser at Arizona State University has called “the single most powerful image in the history of limnology”.

Figure 1. Lake 226 following fertilization with carbon, nitrogen, and phosphorus (below divider) versus carbon and nitrogen only (above divider).

Just a few months after the nutrient additions began, the side of the lake receiving C + N + P was completely covered by a bloom of blue-green algae whereas algae levels on the C + N side were essentially unchanged from when the nutrient additions began. It was abundantly clear that phosphorus had been limiting the growth of algae in Lake 226.

In a final experiment, Schindler et al. manipulated a third lake, Lake 304, to test whether, and how quickly, a lake could recover from phosphorus-induced eutrophication. The team measured the concentration of algae in Lake 304 at approximately monthly intervals over the course of five years, between 1969 and 1973. For three of those years, 1971–1973, the lake received additions of carbon and nitrogen, and for two years, 1971–1972, also received phosphorus. The experiment therefore mimicked what might happen if governments took steps to limit the amount of phosphorus entering a polluted water body. The general finding was that summertime algal concentrations increased dramatically in 1971 and 1972 when the lake was being fertilized with C + N + P, but returned to near baseline levels in 1973 after phosphorus fertilization was discontinued.


Figure 2. Chlorophyll a concentrations (a proxy for algal growth) in Lake 304 from 19691973. Boxplots are based on data extracted from Figure 2 of Schindler 1974 and only include samples from mid-summer; between June and September.

This result again demonstrated that algal growth was limited by phosphorus, and furthermore showed that reducing the amount of phosphorus entering a polluted lake could lead to rapid recovery.

This series of experiments led by Schindler was instrumental in convincing scientists, governments, and the public that phosphorus played a significant role in eutrophication and should therefore be regulated. Throughout the 1970s and 80s, the Canadian government and many American states enacted legislation banning or limiting the use of phosphorus in laundry detergents and other cleaning products.

The Experimental Lakes Area

Schindler’s work on eutrophication represents just a small fraction of the world-class research conducted at the Experimental Lakes Area. Over the past 40 years, research carried out at the ELA has led to 676 peer-reviewed publications including 8 papers in the journal Nature and 15 in Science (the most prestigious scientific journals). In addition, 116 graduate theses and 158 technical reports have been based on research at the ELA.

Much of the research carried out at the ELA has been highly relevant to public policy. Scientists with the Department of Fisheries and Oceans and researchers from universities across Canada and the world have used the ELA to determine how aquatic ecosystems are impacted by things like synthetic hormones from birth control pills, acid rain, aquaculture, common forms of habitat destruction such as the removal of aquatic vegetation, hydroelectric reservoirs, eutrophication, and the accumulation of heavy metals and organic toxicants. A news article in the journal Science refers to the ELA as “Ecology’s supercollider” and James Elser of Arizona State University suggests that “it’s hard to overstate the impact [the ELA] has had”.

Tragically, the Canadian government feels that $600,000 per year (the ELA’s estimated operating budget) is too high a price to pay for world-class environmental science. In case it isn’t clear, I emphatically disagree.

____________________________________

Schindler, D. (1974). Eutrophication and Recovery in Experimental Lakes: Implications for Lake Management Science, 184 (4139), 897-899 DOI: 10.1126/science.184.4139.897