Can seabirds overfish a resource? The case of cormorants in Estonia

Published in Open Lab 2010, a print compilation of the best science blog posts of the year.

“Overfishing” is a term associated with resource depletion, extinction, and human greed.  While the definition of overfishing is technically a subjective measure (How much fishing is too much?), it has been widely accepted to mean catching more of an aquatic resource than can be replenished naturally by the system.  The idea of depleting a marine resource is ubiquitous and familiar these days, with the bluefin tuna even featured as the cover article of the New York Times Magazine this past June.

That’s a lot of mackerel for one net! Image: NOAA

The idea may be commonplace now, but this was not always so.  A 2003 paper by Nicholas Dulvy and others enumerates the reasons why it was long believed that marine populations were more resilient than terrestrial species, and less likely to go extinct due to overfishing, habitat loss, invasive species, disease, and other causes.  Jean Baptiste de Lamark himself was a proponent of the “paradigm of ocean inexhaustibility” due to the high fecundity of fish.  He (and others) argued that because fish lay so many eggs and have excessive offspring (with little care put into each), we could never actually catch enough of a population to cause any damage.  One problem with this argument is that fecundity often increases with size of an individual.  Since we selectively catch larger fish, we’re catching the most reproductively able of a population and causing a large impact per fish caught.  Other arguments about the impossibility of aquatic extinction include broad geographic range and dispersal, and that economic extinction of a fishery would precede biological extinction of a species (all of which have counter-arguments).

In all the discussion of overfishing, it is always humans that are doing the fishing to the detriment of non-human species, either through depletion of a fished species itself, or by reducing resources for other species that rely on it for prey.  It is we humans who must reduce our impacts and allot resources for other species on our fair planet.

Last month (August 2010), an article from ICES Journal of Marine Science asks whether humans are the only species capable of overfishing.  More interesting than the research itself is the questions it raises about our own relationship with “nature.”

The story of cormorants in the Baltic Sea

 

The Great Cormorant (Phalacrocorax carbo) is a seabird that lives in the Baltic Sea, along with many other locales.  According to the Helsinki Commission, in the 1950s and 1960s the bird was overhunted to near-extinction locally, at which point they were put under government protection.  Over the rest of the 20th century, the bird population improved dramatically, recolonizing old haunts with great success.  They were so successful that they began expanding their original range, initially colonizing Estonia in 1983.  In 2005, there were 20 great cormorant colonies in Estonia with an estimated 10,000 nesting pairs.

Over the course of this period, fishing decreased in Estonia waters, in part to conserve the estuarine wetlands that are important for bird migration and fish spawning.  Despite this, many commercially valuable fish stocks plummeted.  Though working with a limited data set (fish were sampled only in 1995 and 2005), in the ICES paper, the scientists satisfactorily concluded that this loss of fish species was due to overexploitation, not by humans, but by these great cormorant colonies.  The cormorants were fishing 10-20 times more than the commercial catch of fish species such as perch Perca fluviatilis and roach Rutilus rutilus, decreasing the fishes’ ability to recover year after year.

Population development of the Cormorant in the eastern and northern Baltic (Estonia and Finland). Data from SYKE (2008, 2009), Lilleleht (2008), and Evironmental Board of Estonia (2009, pers. com). From the Helsinki Commission

How this questions our typical relationship with “nature”

This is an interesting story for several reasons.  The birds were able to spread their range as far as they did and, in the end, compete with humans for food resources because we were trying to protect them.  Their near-extinction in the 1950s probably led the government to be hesitant to lift protection because the birds were no longer birds, but a symbol of species recovery.  After such a great success, how could we take their resources away and potentially lead them to extinction once more?

The fact alone that they are seabirds also makes their presence hard to define.  Some cases of “invasive species” are very clear cut.  For example, brown tree snakes are not from Guam, but were brought there and are now wreaking havoc on native animal populations.  But seabirds toe the line.  They are able to fly anywhere, and simply live on colonies at sea.  Who are we to determine where geographically those colonies exist?  The authors of the paper do not even use the word “invasive” to describe the expansion of great cormorants into Estonia until the end of the paper.

Are these birds invasive?  It depends on your definition of the term.  Some would argue that, yes, they did not live there before but do now, and are affecting the ecosystem to the detriment of other species.  But it’s all relative: invasive species are defined by an anthropocentric view of the world, in which what is “natural” is the distribution of organisms we initially encountered and recorded.  But who are we to decide that a species belongs or does not belong in a certain place?  Who are we to tell the cormorants that they cannot live on that rock near an ample food supply?  We’re the only species that sets these sorts of boundaries; all the other species are just trying to utilize resources and survive.

The idea that humans are the only species able to overexploit a resource is also anthropocentric.  It makes Homo sapiens the center of the world, the ones who determine the fate of all other organisms, who can harvest them for ourselves or choose to spare them.  This case of the cormorants places us back in our role as a competitive species: we have to decide whether or not we are willing to take back our resource, even if it means losing some of these big, aesthetically-valuable cormorants.  We are no longer the masters of nature, but rather are inserted back into it.

I hope I manage to keep up with this case and find out what happens in Estonia.  At this point, “taking back our resource” would not mean going in and competing by fishing; there are too many cormorants, so we would simply deplete the resources further.  Instead, the Estonian government would have to enter the colonies and manage the population through oiling or pricking eggs to kill the developing birds (the Helsinki Commission estimates that this is done to 18% of nests in Denmark).  Already 10,000-20,000 birds are shot in the Baltic Sea area each year, but public protests limit the amount of population control that is performed.

We may have simply lost control of the situation at this point.  There may just be too many cormorants to keep them from overfishing, for our own sake or to preserve the fish as an ecosystem resource.

Dulvy, N., Sadovy, Y., & Reynolds, J. (2003). Extinction vulnerability in marine populations Fish and Fisheries, 4 (1), 25-64 DOI: 10.1046/j.1467-2979.2003.00105.x

Vetemaa, M., Eschbaum, R., Albert, A., Saks, L., Verliin, A., Jurgens, K., Kesler, M., Hubel, K., Hannesson, R., & Saat, T. (2010). Changes in fish stocks in an Estonian estuary: overfishing by cormorants? ICES Journal of Marine Science DOI: 10.1093/icesjms/fsq113

DMS(P): the amazing story of a pervasive indicator molecule in the marine food web

Dimethylsulfide.  Does that word mean anything to you?  “Why yes,” you organic chemistry nerds may say, “It clearly is a molecule of sulfur with two methyl groups attached.”  That’s as far as I could have gotten – until this past week, when I inundated myself with information on dimethylsulfide (DMS) due to a paper published in Science.  Now I’m enlightened – what a wonderful molecule!  Let me spoil it for you: it is simultaneously a defense mechanism, a chemical cue pervasive throughout the marine food web, and an effector on the earth’s climate.  (See illustration at bottom of post for summary.)  That’s right.  Just a sulfur molecule with two methyl groups attached.  Now let’s back up a bit.

DMS is a sulfur compound that accounts for 50-60% of the total natural reduced sulfur flux to the atmosphere (even more than either volcanoes or vegetation).  While sulfur in the atmosphere can cause acid rain, it is also very important, as it helps form clouds.  In order for water to transition from a gas to liquid in the atmosphere, it needs a small particle in the air to adhere onto, known as a cloud condensation nucleus.  Sulfur oxide, which can be derived from DMS, is one of these particles.  Clouds not only carry our precipitation, but help to reflect sunlight (and thus heat) back into space, affecting our planet’s climate.

After the realization of its importance as a cloud condensation nucleus, scientists began to look for DMS’s planetary source and found that 95% of the atmospheric DMS originates in the oceans – but from where?  As illustrated in my figure, it is actually formed in certain species of phytoplankton and released when cells leak, most often due to herbivory by other organisms.  The phytoplankton itself actually makes a molecule called DMSP (dimethylsuphoniopropionate, if you must know).  When its cell wall begins to break down, stores of DMSP (from an unknown location within the cell) and an enzyme, DMSP-lyase, are released into the surrounding water.  This DMSP-lyase removes the P-group, leaving us with our favorite molecule of the day, DMS.

In 1987, the CLAW hypothesis (named for its authors) was put forward by James Lovelock and a handful of his lackeys to support his infamous Gaia hypothesis which suggests that microorganisms regulate the Earth’s climate to maintain conditions suitable for life.  CLAW hypothesized that levels of DMSP and its P-cleaving enzyme in phytoplankton are regulated by light and temperature, with greater amounts of DMSP produced when it gets warm in order to send more DMS into the atmosphere, deflecting sunlight and reducing global temperatures.  However, like most support for the Gaia hypothesis, this idea requires that phytoplankton act altruistically, releasing the DMS for the good of the planet, which does not make much sense in light of natural selection.  (A good review of this and the above sections can be found in this paper by Rafel Simo.)

A 2001 MEPS paper by Kathryn Van Alstyne and others provides evidence that the release of DMSP and DMSP-lyase by phytoplankton is actually a chemical defense mechanism.  After DMSP-lyase activity, the resulting products are DMS and acrylase or acrylic acid.  The authors found that acrylic acid deterred grazing by two species of sea urchins on algae, and they suggest that this is due to an aversion to acidity by the urchin itself or that the acid irritates its gut microbes.  While the evidence is not directly causative, as the authors showed a reaction to acrylic acid and not to DMSP-produced acrylic acid in vivo, it does suggest (with other evidence) that the important part of this reaction to the phytoplankton is not DMS, but rather its byproduct.

Fig. 1 from Van Alstyne et al. (2001), showing the DMSP-lyase reaction

Smaller grazers, such as isopods, had no reaction to the acrylic acid in that paper.  But a paper published in Science this week (July 16 2010) by Justin Seymour, Rafel Simo, and others looks into the effects of DMSP on the smallest grazers: microbes.  Using “microfluid technology” (see details at end of post), the researchers measured the strength of attraction of 4 different types of microbes (7 species) to varying concentrations of DMSP, DMS, DMSO (dimethylsulfoxide, a DMS and DMSP degradation product), GBT (glycine betaine, a molecule analogous to DMSP in structure and function), and artificial seawater (as a control).

1. Each of the 3 species of autotrophic plankton reacted differently to DMSP in the water.  The algae Micromonas pusilla showed strong attraction to DMSP, taking it up presumably as a carbon and sulfur source.  The cyanobacterium Synechococcus sp. showed no reaction.  Most strangely, the algae Dunaliella tertiolecta moved very strongly toward DMSP, but not to assimilate it directly; rather, it cleaved the molecule into DMS extracellularly and potentially assimilated that molecule instead.  The authors do not know why this action occurs.
2. Two species of bacteria, Pseudoalteromonas haloplanktis and Silicibacter sp., each moved toward the DMSP for assimilation as part of their carbon and sulfur requirements.
3. Two consumers, one a herbivore to eat the algae itself (Oxyrrhis marina) and the other a bacteriovore which strove to eat the bacteria consuming the DMSP, each showed positive chemotaxis and moved toward the DMSP source.

This last part is the most interesting: these two microbe species use the DMSP as a chemical signal that there is food around.  Out of all the molecules that could leak from the burst cell and indicate prey, it is this very molecule, DMSP, that does the trick.

But wait: didn’t the 2001 paper I just wrote about suggest that DMSP is a chemical defense of phytoplankton?  What is it doing drawing in its own predators?  The authors suggest that previous studies have flawed experimental design, releasing far too much bulk DMSP into the environment in contrast to their own “microfluid technology.”  Previous studies, such as a 1997 Nature paper by Gordon Wolfe and a 2003 paper by Suzanne Strom, found that O. marina has a higher tolerance to digesting DMSP and is less repelled than other species.  More work should be done in order to get to the root of this contradiction.

Thus far, we have DMSP attracting bacteria to consume the DMSP itself, drawing in an herbivore to consume the DMSP-producer, and a bacteriovore attracted to the DMSP in order to find its own bacterial prey.  This is not the end of the story, as DMSP is a prey indicator at higher trophic levels as well.  A 2008 Science paper out of UC-Davis and UNC found that planktivorous fish use DMSP as a foraging cue, aggregating near DMSP hotspots.  Furthermore, Gabrielle Nevitt reviewed literature in 2008 on seabirds (Order: Procellariiformes) using DMS as an olfactory cue to identify patches of its own prey, fish and squid, feeding on the zooplankton and its phytoplankton prey.  A similar pattern has also been found in seals and whale sharks.

The evolutionary implications of this are astounding.  It seems as though many molecules released from a leaky phytoplankton cell could be used as indicators of these clusters of consumption.  However, DMSP has something special: sulfur.  We all know that smell, and perhaps it is this stinkiness that has allowed it to become such a pervasive indicator throughout the marine food web.  In her review, Nevitt discusses the evolution of DMS-sensitivity in seabirds, and using phylogenetic trees, shows that only the species that are reared in dark burrows, relying on smell alone to identify food, currently have DMS-sensitivity.  How did this apparent convergent evolution occur?  Is it convergent?  (I have no answers to these questions.)

Are there any implications for climate in these findings, as DMSP is indirectly responsible for increased albedo (sunlight reflection) in our atmosphere?  I doubt that there are any direct consequences that we can enumerate.  As all biogeochemists know, the stuff of the air frequently comes from the stuff we live on and in: soil and water.  This is simply another tie to the way microbes and abiotic stuffs relate to climate-regulating molecules.  The authors of this week’s Science paper note that “microbial behaviors, played out over microscale chemical landscapes, shape planktonic food webs while potentially influencing climate at global scales.”  DMS as a prey cue should create a positive feedback loop, drawing more herbivores to open more cells and leak increasing DMSP, which in turn draws more herbivores.  Some studies show varying ties of DMSP production to species, light, temperature and salinity (review by Stefels et al. here), but it seems to me that the DMS-as-prey-cue and DMS-as-climate-regulator processes are unlinked, so would not work together in any predictable way.

If you take nothing away, take this: sometimes the universe is more connected than we can imagine.

(Sidenote: should I give up strict science and become a science illustrator?)

NOTES ON MICROFLUID TECHNOLOGY:
The idea behind this technique is that microbes inhabit a “dynamic and patchy nutrient landscape” in which nutrient levels vary over micrometer scales.  The microfluidic device is a chamber designed with the “objective of creating a diffusing band of chemoattractant, to simulate an ephemeral, microscale nutrient patch.”  There is a chamber in the center into which fluorescence-labeled chemoattractant is added to the desired concentration, and then input is cut off.  Thus the chemical will dissipate slowly through the closed chamber, trying to imitate the open ocean.  The researchers then add their microorganisms, and measure their distribution and the distribution of the fluorescent chemical.  This allows the researchers to track the intensity and location of the chemical, as well as the behavior of single organisms.

This information is from a paper in Limnology and Oceanography: Methods by J.R. Seymour, T. Ahmed, and R. Stocker entitled “A microfluidic chemotaxis assay to study microbial behavior in diffusing nutrient patches” (2008: 6 (477-488)).  A pdf copy of this paper is available on Roman Stocker’s webpage, here (pdf warning!).

Here’s a picture of the device, thanks to Roman Stocker.  The blue tube is the microbe input, the green tube is chemical input, and the red tube is for drawing out waste.  It sits on top of a microscope.

DeBose, J., Lema, S., & Nevitt, G. (2008). Dimethylsulfoniopropionate as a Foraging Cue for Reef Fishes Science, 319 (5868), 1356-1356 DOI: 10.1126/science.1151109

Nevitt, G. (2008). Sensory ecology on the high seas: the odor world of the procellariiform seabirds Journal of Experimental Biology, 211 (11), 1706-1713 DOI: 10.1242/jeb.015412

Seymour, J., Simo, R., Ahmed, T., & Stocker, R. (2010). Chemoattraction to Dimethylsulfoniopropionate Throughout the Marine Microbial Food Web Science, 329 (5989), 342-345 DOI: 10.1126/science.1188418

Simó, R. (2001). Production of atmospheric sulfur by oceanic plankton: biogeochemical, ecological and evolutionary links Trends in Ecology & Evolution, 16 (6), 287-294 DOI: 10.1016/S0169-5347(01)02152-8

Stefels, J., Steinke, M., Turner, S., Malin, G., & Belviso, S. (2007). Environmental constraints on the production and removal of the climatically active gas dimethylsulphide (DMS) and implications for ecosystem modelling Biogeochemistry, 83 (1-3), 245-275 DOI: 10.1007/s10533-007-9091-5

Van Alstyne, K., Wolfe, G., Freidenburg, T., Neill, A., & Hicken, C. (2001). Activated defense systems in marine macroalgae: evidence for an ecological role for DMSP cleavage Marine Ecology Progress Series, 213, 53-65 DOI: 10.3354/meps213053

G. V. Wolfe, M. Steinke, & G. O. Kirst (1997). Grazing-activated chemical defence in a unicellular marine alga Nature, 387, 894-897

How did they get there? The colonization of a hydrothermal vent after volcanic eruption

To some people, a volcanic eruption means “Ahh!  Run!  Hot Lava!”  But to others, it means “SCIENCE!”  To those studying hydrothermal vent communities, that is (and a wide berth of geologists).

Hydrothermal vents are cracks in the seafloor formed when tectonic plates spread apart, which spew out hot, mineral-rich water from the interior of the earth.  Thus they are most commonly found on sea ridges, such as the Mid-Atlantic Ridge and the East Pacific Rise, where two or more tectonic plates meet and clash underwater.  These vents host exotic communities of organisms.  All the hot, mineral-rich water attacts chemosynthetic bacteria, or bacteria that get their energy from chemicals instead of the sun (as there is no sunlight on the seafloor), which in turn attract organisms that graze on the bacteria.

An important organism in many hydrothermal vent communities is the tube worm.  It can grow a couple meters long and lives inside of a tube that it builds for itself out of chitin, into which they can retreat in case predators are around.  The weirdest thing about tube worms: they have no mouth or digestive tract!  For their food, they require a symbiotic relationship with chemosymbiotic bacteria, drawing their nutrients from the bacteria, presumably in return for the nice home.

A hydrothermal vent in the Pacific Ocean. You can see tube worms (red worms in white tube) in the foreground, and the chemical-rich water (hydrogen sulfide, in this case) shooting off like a plume of smoke in the background.

This is just one of the many strange and diverse organisms found in hydrothermal vent communities.  There have been over 300 new species identified since the first vent was discovered in 1977.  However, due to their nature, these vents and their communities are ephemeral: just as easily as they are created by the spreading of the earth’s plates, they are just as easily closed off.  Once the mineral-rich water is gone, so are the bacteria, causing many of the species inhabiting the vent (including tube worms) to go locally extinct.

These communities present an interesting question to biologists: from where do these communities come?  The two dominant hypotheses are: (1) there is a well-mixed pool of larvae that colonize new vents (similar to the “everything is everywhere” hypothesis about microbial distribution I pondered here), and (2) vent communities are created from larvae supplied by local populations through migration.  (Side note: Marine dispersal has been a hot topic on Research Blogging this week!  I recommend this post by the recently-graduated LabRat (Congratulations!) on vertical distribution of microbes by hitchhiking on plankton, as well as this post on Southern Fried Scientist about how “ghost populations” affect marine migration.)

A group of scientists from Woods Hole had been studying a number of vents along the East Pacific Rise, a huge ridge cutting across the center of the Pacific, when they noticed that one of their communities had disappeared!  Lava from an underwater volcanic eruption had paved over the vents and their communities, killing off species in almost the entire area (RIP).  But this lava did not clog all the vents: some of the vents (as well as freshly created ones) continued to spew the hot, mineral-rich water.  As the scientists had collected data on the local pool of larvae and the pre-eruption community, it presented a perfect opportunity to study marine dispersal by comparing the vent communities in this area before and after the eruption.  If there is a general pool of larvae, they expected a similar community before and after the event.  A distinct community post-eruption would signal local migration.

What do these species look like? Mostly gastropods. I also included the two different tubeworm species the scientists found at the vent communities. Most images from http://www.whoi.edu/vent-larval-id/GastSize.htm. Click image for larger view!

In their 2010 PNAS paper, the scientists found that both the larvae found in the vicinity and the species that settled to colonize the vent area differed drastically from those found before (see figure below).  The dominant tubeworm species was Tevnia jeichonana, replacing Riftia pachyptia (see figure above for images).  Most interesting was the arrival of Ctenopelta porifera, which had never been found at the site before – the nearest known population is 300 km away!  These data suggest that, at the least initial community, arrives through the second hypothesis: supply through local populations and not a “well-mixed, time-invariant larval pool.”

The colonizers (warm and hot vents) and larvae differed significantly before and after the eruption. Click image for larger view.

There are some possible reasons for this.  The new vents could be spewing water that has a different biochemical makeup, supporting a distinct species of bacteria and thus a distinct community of colonizers.  The authors hadn’t done chemical analysis yet (which would have made it a stronger paper, in my opinion), but offered this as a possibility.  Additionally, as I mentioned above, this is just the initial community.  The authors found T. jerichonana as the dominant tubeworm species, which they have seen replaced by R. pachyptila (the previous dominant species) and later by the mussel Bathymodiolus thermophilus at other vents over time.   This creates the possibility that these vents are colonized initially through local populations and after they are “broken in” and deemed habitable, other more robust species move in, ousting the previous colonizers.  Where these species come from, either from a well-mixed pool or local populations, only time will tell.

And that’s what’s so great about ecology: this experiment isn’t over!  The scientists are surely continuing to collect data on these vent communities, and over the decades we will be able to follow them through their succession.  So keep your eyes open for the next paper from these scientists to hear the rest of the story…

Mullineaux, L., Adams, D., Mills, S., & Beaulieu, S. (2010). Larvae from afar colonize deep-sea hydrothermal vents after a catastrophic eruption Proceedings of the National Academy of Sciences, 107 (17), 7829-7834 DOI: 10.1073/pnas.0913187107

A hydrothermal vent in the Pacific Ocean. You can see tube worms (red worms in white tube) in the foreground, and the chemical-rich water (hydrogen sulfide, in this case) shooting off like a plume of smoke in the background.

Molecular biology and globsters: dashing cryptozoologists’ dreams

This post was featured in Dave Munger‘s Research Blogging column for Seed Magazine, “Spineless But Deadly.”  Thanks, Dave!

On July 29th 2008, the day I turned 21 years, I received the best thing I could ask for: a birthday gift from Poseidon.

I was living in Newport, OR at the time.  After a long morning of observing nesting seabirds through a telescope, I returned home for what I presumed to be a long night ahead at the Rogue brewery across the street.  But I was to have more excitement first: I had gotten an email from the education director at Hatfield, informing me that 9-foot robust clubhook squid carcass had washed up on the beach just 20 miles away.  Even though I never got to see it, as it quickly made its way into an industrial freezer for preservation and future dissection, my excitement could not be quenched because obviously this was the ultimate gift from the sea (my true love).

I didn't get to see the real clubhook squid - but I did receive this lovely cake from my dear friend Lanaya the day I turned 21.

I have long had an obsession with squids, particularly of the large persuasion.  How could I not?  They are the closest thing to sea monsters that we’ve got!  They’re grotesque and mysterious, yet graceful (not really, only in my dreams — they’re actually quite slow) and sometimes colossal.  As I grew older, I realized that I was not alone, but there was a large, undefineable community of squid-lovers.  It seems to be in our nature to seek monstrosities: creatures new to science, alien, and potentially terrible.

This seemingly universal fascination and attraction to monsters is best exemplified in the phenomenon of globsters, also known as blobsters.  A globster is a blob-like animal that washes up on the shores of oceans and lakes which is morphologically unidentifiable, thus lending itself to be described as a variety of terrifying monsters as the viewer deems fit.

An early globster was the St. Augustine Monster, discovered on the coast of Florida in 1896 (a, below) by 2 young boys, originally suspected to be a giant octopus.  In 1977, a Japanese fishing trawler pulled up a hunk of flesh (dubbed “New Nessie“) (b) imagined to be an ancient underwater dinosaur, the plesoisaur, off the coast of New Zealand.  The Bermuda Blob (c) was found in Bermuda in 1988 and is the most blob-like of these three examples.  These are just three examples I chose to give here; there are more recorded examples, and many unrecorded.  (See Richard Ellis’s book Monsters of the Sea for a full history of globsters.)

Click image for larger view. Images compiled from Wikipedia.

In our modern reductionist mindset, it seems obvious what these things really are: just dead animals that have been floating out at sea, decomposing, and are thus unrecognizable by the time they wash up to shore.  But even now we are discovering hundreds of novel sea creatures every year; imagine a century ago when the sea was more mysterious and potentially dangerous.  How could a scientist identify a half-decomposed species and persuade the masses that it was not, in fact, the remains of a monster from the deep?

The answer lies in molecular analysis.  The journal Biological Bulletin published a paper in 2002 by Carr et al. identifying the the Newfoundland Blob, and another paper in 2004 by Pierce et al. looking at a variety of blobsters (including St. Augustine’s Monster, a above), but focusing on the 2003 Chilean Blob and the 1996 Nantucket Blob due to sample quality.

Both studies retrieved DNA from samples from the various blobs and sequenced their mitochondrial DNA (mtDNA).  Mitochondrial DNA is particularly useful for taxonomic identification.  It is a piece of DNA separate from your genome, found not in the cell nucleus but in the energy-producing part of the cell, the mitochondria, and is relatively well-conserved within species for easier identification.  Comparing the mtDNA sequences from their samples with known sequences from whales and sharks, Cass et al. found that the Newfoundland Blob is a decomposed sperm whale.  Similarly, Pierce et al. found that the Chilean Blob matched a sperm whale, while the Nantucket Blob was a finback whale.

Pierce et al. took it a step further and compared the amino acid compositions and microscope photos of tissue samples from many other blobsters, including St. Augustine’s Monster (a), the Bermuda Blob (c) and the 1960 Tasmanian Globster to classify those blobs as well.  They had an identical composition to the whale blubber of the Chilean blob, suggesting that these are also whale species and not large octopuses.

And thus, they’ve dashed the dreams of people all around the world who dream of sea monsters – but that was not their intent.  In fact, the authors themselves were hoping to find a new species.  Pierce et al. finish their paper with the sentence:

Once again, to our disappointment, we have not found any evidence that any of the blobs are the remains of gigantic octopods, or sea monsters of unknown species.

So do not think that the scientists are trying to say “I told you so.”  Rather, they dream big like the rest of us.

These analyses do not mean that we cannot continue dreaming; on the contrary, waterlogged animals are found regularly and each must be debunked individually.  Just this month, a strange creature was found on the shore of a lake in Northern Ontario, with a terrifying, hairless face and”creepy fangs,” covered by hair on the rest of its body.  Its discoverers suggested it was an omajinaakoo or “Ugly One,” a mythological creature considered a bad omen by First Nations (Native American) tribes.  Just this week this idea was debunked: it turned out to be a common animal, the American Mink, in a horrid state.

But don’t let these debunkings get you down.  Always keep your guard up for the excitement and horror of an undiscovered monsters.  It will at least keep you entertained.

Carr, S., Marshall, H., Johnstone, K., Pynn, L., & Stenson, G. (2002). How to Tell a Sea Monster: Molecular Discrimination of Large Marine Animals of the North Atlantic Biological Bulletin, 202 (1) DOI: 10.2307/1543217

Pierce, S., Massey, S., Curtis, N., Smith, G., Olavarria, C., & Maugel, T. (2004). Microscopic, Biochemical, and Molecular Characteristics of the Chilean Blob and a Comparison with the Remains of Other Sea Monsters: Nothing but Whales Biological Bulletin, 206 (3) DOI: 10.2307/1543636