Archive for December, 2010

Sky Sharks And SCUBA

Sunday, December 19th, 2010

Hi Folks,

My wife and I got treated to quite a show yesterday.  For several hours, a male prairie falcon was cruising around our yard hunting doves.   These latter birds are Eurasian collared doves, one of several introduced pest birds (think large white/gray/tan pigeons) found locally – thesea are  probably descended from birds released by some non-thinking idiot who decided it would be cool to release doves symbolizing something or other at a ceremony somewhere near here.  Anyway, said skyrats appeared about four years ago, and have been doing well here.

Eurasian Collared Dove

Periodically, though, a truly native sky shark comes by to thin the herd a bit, and that is what happened yesterday.   It was great entertainment to watch the falcon, though I doubt the doves thought so. :-)  I saw him miss his target by inches on one pass; the dove was surprisingly agile in the air when the situation warranted!   The falcon was around for a while, and then vanished.   I hope he finally got dinner and settled down near by to enjoy his repast.

Almost exactly a year ago, we had a similar opportunity to watch a goshawk for a few days, and the second picture, below, shows the final outcome.  The first picture was taken a few days before the second one, and it appeared to be the same animal.  In the second image, the hawk is standing over his plucked prey that he has been eating.

Sharp-shinned Hawk in the poplar outside my office window.

Sharp-Shinned Hawk and Dinner

It was an amazing show.

Of such events, are the sciences of behavioral biology, or ethology, and ecology, made.  And people who study these things in terrestrial environments truly lose out.  I used to tell my students that one of the very neat things about being an ecologist who worked subtidally using SCUBA was that one got to see a lot more interactions than one’s terresterially-bound counterparts.

If you think about it, how many times have you seen a predatory animal in nature around you (excluding those events caused by humanity or human pets ) actually kill and eat a prey organism?  I would wager that the total sum of those events witnessed by anybody is pretty small; I know it is with me, and I look for them.  It is possible to calculate some sort estimat of the odds of seeing such an interaction at any given moment.  For example, if a person is 35 years old, that person has been alive about 1 billion seconds.  If each second is a discrete a moment of observation, the rough, back-of-the-envelope odds of having seen such an event through that person’s lifetime are easy to work out.  First, assume that about of the third of the time has been spent sleeping, so subtract a third of the billion away, phffftt!, and now there 667,000,000 million potential moments of observations.  Then assume that for the first third of the persons’s life she or he was effectively unaware of the world (childhood, teen-aged years, and so forth), so subtract a third of the previous remains and now there about 444,700,000 million potential observational moments.  Now, drop out a another third for meals, and other daily mindless activities, and now there about 296,400,000 million observational times.  Being generous, let’s say our victim subject was outside observing nature 1/10 of each day (and I think that will be a vast over estimate for most folks, but, what the hey, let’s go with it), so now there are 29,640,000 potential moments of observation.  And if that person witnessed 10 natural events wherein one animal killed and ate another (and I suspect that would an overestimate), that means our subject’s odds of seeing such an event were 10 in 29,640,000, or 1/2,964,000, or (very roughly) 0.0000003.

Pretty slim odds (!) of seeing some interesting natural event such as predation.

Back to my point about working underwater in the marine world, I could see animals kill and eat other animals many times during a hour’s dive, and often did so.   Below are a couple of images  recording some of those times (and be sure to click on the sculpin image to see the shrimp’s antenna).   Obviously, the moral of the story, of course, is that one must dive to really observe and understand nature.

A Buffalo Sculpin, Enophrys bison, that has just eaten a shrimp, note the antenna visible protruding from the mouth.

A red rock crab, Cancer productus, eating a scallop.

Yeah, sure!!!

But the point that visible large animal to animal interactions are more evident in the marine environment is, I think, a valid one.

Behavior and Marine Aquariums

Thinking about the point made above, and making a not-so-tortuous connection to marine aquaria, those boxes of water full of critters may be (depending, of course, on how the boxes are set up, and what’s in them) quite reasonable analogues to a natural environment.  And that means, any aquarist with such a tank should expect to see predatory (and other “natural” ecological or behavioral) events occurring with some reasonable frequency in their systems.

And, of course, all of us aquarists (or at least of us who observe our systems) do see these events.  Everytime we feed some live animal to our livestock, we see predation, albeit those are staged events, but with suspension-feeding animals, corals for example, within the staged event, the actual feeding behavior on the part of the coral, is likely essentially the same as when the “real thing” occurs in nature.  But even if those “wo/man-made” events are factored out, all aquarists have seen unintened predation occur in our systems, and sometimes rather frequently, as when when a newly-observed acoel flatworm on the aquarium wall is seen to capture and eat a copepod.  In fact, by observing some of these types of events any aquarist worth their artificial (sea)-salt can – for some animals, at least – see interactions that have never been seen in nature, and depending on the interaction – such as with the flatworm and copepod example – such events may be exactly what occurs in the real world, or a mimic so close that the difference is immaterial.

So, folks, on this cold winter, while the snow outside blankets the northern hemisphere, those of you with coral reef aquaria kick back and relax and enjoy the tropical world in your living room.

It’s a world of your making and if you have done your job, properly, it is a VERY real world.

For the rest of you, it is time to shovel snow!

Until later,

Cheers,

Coral Problems

Friday, December 17th, 2010

Hi Folks,

A most interesting and interesting article discussing the problems with identifying stony corals, in particular, some species of Hawai’ian Montipora has recent been published.

The background for the article is that last year several parties petitioned to have 83 stony corals to be listed under the United States Endangered Species Act. The National Marine Fisheries Service (NMFS), a branch of the National Oceanic and Atmospheric Administration (NOAA) is charged with assessing the coral species in question to determine, among other things, if they actually are endangered.  If the corals are listed, the act is supposed to provide some more protection for the species, and probably most importantly, designate critical habitat for these corals.

Of course, the whole “assessment” process ultimately depends upon somebody’s ability to identify individual colonies of coral species in question and that, in turn, depends upon the validity scientific description of those species.  The basic fundamental issues are:

1) Is the given species well-enough described to be reliably identified?  Keep in mind, that by being listed on the petition, at least somebody thinks the indivual colonies in that species can be identified.

2) If the species is identifable, can it be assessed to determine if it is endangered?

The article discussed in the Coral feature was officially published on 2 December, 2010, in the electronic (online and free access) peer-reviewed journal, PLoS One:

 

Forsman ZH, Concepcion GT, Haverkort RD, Shaw RW, Maragos JE, et al. (2010) Ecomorph or Endangered Coral? DNA and Microstructure Reveal Hawaiian Species Complexes: Montipora dilatata/flabellata/turgescens & M. patula/verrilli PLoS ONE 5(12): e15021. doi:10.1371/journal.pone.

I urge you all to read, at least, the Abstract (= the authors’ short summery) of the article, but I am also a realist and realize that while a few of you will look at the Abstract, and some of you may actually read or download and save the article, most people who scan this blog probably won’t.

So…

Here is a brief summary of the summary – if you will, an abstracted abstract.  And if this is creative document would it then be “abstract art?”    Yeah, I know, “Boo!… hiss!”

The researchers examined the genetic codes for a relatively large number of well-known and well-characterised proteins found in the corals’ cells, as well, they also looked at how the subcellular structures called mitochondria vary genetically between the samples.  They also microscopically compared, in fine detail, some of the visible physical structures of each specimen.  

When added together, these different examinations revealed four distinct groupings of specimens (called “clades”), and when each specimen was identified with traditional taxonomic methods, the four clades contained these species: I) M. patula/M. verrilli, II) M. cf. incrassata, III) M. capitata, IV) M. dilatata/M. flabellata/M. cf. turgescens.  So, sophisticated statistical analyses of skeletal microstructure and genetics separated specimens of 7 “species,” based on traditional taxonomy, into 4 groups that represent -probably- actual groups.  I think whether or not one wants to consider that each of these groups represents a species is probably dependent on how one feels about this type of analysis.  To me, yup, I’ll buy in to consideration of each group as representation of a species.  The microcharacters of the size and shape of verrucae or papillae were the only reliable physical characters that could be used in identifying the groups, while gross features such as any aspect of colony-level morphology was so highly variable as to be useless.

The authors noted that previous studies on how observable structures in corals vary from specimen to specimen have revealed that fragments taken from the same colony can exhibit strikingly different growth forms if grown in different environments.   Additionally, the extent of both genetic and morphological intraspecific variation in corals is poorly understood. This is clearly creates problems for assessment of species in the context of the Endangered Species Act as  structurally-based taxonomy – not molecular or genetic information – is the current basis for estimating species distributions, abundance, and extinction risk.

This study identified no fixed genetic or fine-scale morphological differences between M. flabellata, M. cf. turgescens, and M. dilatata, or between M. patula and M. verilli; in other words, these 5 named species appear to be only 2 natural species.  The authors noted that the geographic ranges of these groups are likely to extend beyond Hawai’i into the central Pacific and that individuals within “species” of these complexes are either actively interbreeding (which means they are not separate species), or they are from separate species that are very closely related (e.g., evolutionarily separated within the last one million years) and cannot be distinguished from one another.  Now that these complexes have been identified, work is needed to determine if the nominal species within each complex freely interbreed.

Finally, the authors note:

Unfortunately, this study provides little guidance for determining if these specific species are valid and should be listed under the ESA, but perhaps more importantly; it highlights major gaps in the present understanding of species as opposed to population-level variation in corals. This study is an example of how knowledge of species boundaries in corals is not only necessary for understanding patterns and processes of biodiversity and evolution, but is essential for conservation.

In short, the article is a “fun read.” 

One of the many take home messages is obviously that corals are exceptionally difficult critters to identify.  Generally, if we choose the proper characters, we can identify them to genus.  Beyond that… don’t even try.  As it stands now, we have so few data across the range of most tropical stony reef-forming (and presumably, non-reef forming as well) corals, that distinguishing any specific species is an impossible task. 

Enjoy the article!!

Cheers,

Angels of Death

Wednesday, December 15th, 2010

Hi Folks,

Here are a couple of great links pirated from the Deep Sea News blog.

The subject of that blog’s discussion is what the author calls “sea angels,” rather beautiful predatory swimming snails in the genus Clione.   Embedded below is a movie of one swimming lifted from YouTube.   These pretty liddle snails were called “sea butterflies” in the Pacific NW – off the British Columbia and Washington coasts, where I had many chances to observe them, both during and after my graduate studies.

In that area, the common species reaches lengths of about 2 cm – 3cm, roughly an inch or so, but most of the individuals I have seen have been smaller.   These are shell-less snails, found in the water of the colder oceans through out the world.  They swim all their lives.

“Sea angels” and “sea butterflies” ….. ah…. such cute names…

Sorta like calling a hunting tiger, “Fluffy,” or a semi-starved, very hungry, fresh-from-hibernation-and-in-a-(REALLY)-bad-mood Grizzly bear, “Snuggles.”  

Individuals in Clione species snails are specialized predators that appear obligately bound to eat only another pelagic swimming snail.  At least that is the reading from the snail biology gospel; in reality I don’t think they have been studied well enough to know if they have any alternative prey.   While Clione individuals lack shells, their prey do have shells and look rather like a regular snail; both species have large extensions of their foot which they flap like wings.  This gives all of these snails the group name of Pteropods, or “wing-foot,” snails. 

I have embeded another movie, this one showing Clione individuals attacking and eating their prey, Limacina.  And as you watch the movie, I think you will see why I consider the name of Sea Angel to be a bit…. inappropriate.  Unless, that is, it is modified to be the “Sea Angel of Death.”

Swimmers near bathing beaches should be thankful that Clione individuals don’t reach about 2 m long (6.6 ft) and have a taste for humans.

A few times when I was teaching a course about Marine Invertebrates at a university field station/marine laboratory on Vancouver Island, I was lucky enough to be able to have had my theaching assistants collect some individuals both Clione and Limacina within a day or two of one another.   For the class, I would take a large graduated cylinder – these are about 3 feet long and several inches in diameter.  And then I would put in one or two Clione individuals and let them become acclimated, typically that only took a minute or two.  Then I would have the students gather around, and would introduce two or three Limacina.   The rapidity and apparent “ferociousness” (this is a anthropomorphic adjective, but after watching the Clione at work, it seemed to fit, but probably a better adjective is “efficiency”) of the attack would typically leave the students, quite literally, speechless.

Most of the time marine biologists (and I suppose other folks who see such things) typically regard snail predation as a slow and rather leisurely process (albeit animals like Cone snails will also demonstrate the other extreme).  After all, an oyster drill (a muricid whelk) drilling a hole through a bivalve shell is hardly action that is exciting, except, perhaps, to the participants.  

Then, if you are very lucky, you get to see something like Clione attacking a Limacina.  Wow!!!  It kinda blows away the stereotypes and misconceptions…

If you think about this system, wherein one pelagic snail lives by preying only on another pelagic snail, a bit further, I think it is really cause for wonder.  At best, Clione – the predators – are found in aggregations (I really don’t think one could call them “schools,” or “herds” or “flocks”) or patches maybe several meters in volume, and with a few snails per cubic meter.  More often the patches arel larger a few hundred meters on a side, and the density is one or two snails per 5 or 10 cubic meters.

So… lots of water… not many predators….just swimmin’ along being their little sea angelic selves, and with a LOT of water between them.  

Now… the prey – and the same sort of situation.  Lots of water, not many prey.

Two diffuse patches of animals in a very large body of water, what are the odds that any one snail of either species will encounter an individual of the other species?

Well, the odds have to be pretty good or the animals wouldn’t be here!  But still, it is not like these are pedestrians on the sidewalk along a busy street bumping into one another. 

I don’t know of any research that has been done investigating these interactions ecologically in nature.  I suspect the logistics of such research would make it prohibitively expensive (lots of ship time, for example), but the questions raised by the necessity of such interactions are really pretty interesting, I think you will agree.

Perhaps they are being studied at the present.  The author of Deep Sea News blog mentions a student/researcher/photographer, Natalia Chervyakova of Moscow University, who has taken some images of Clione feeding in nature – an amazingly difficult proposition.  Here are some of her images from the White Sea.  These are some of the most spectacular underwater macro photographic images I have ever seen.   And having taken thousands of underwater shots, including a number of planktonic macro shots, I can attest to the skill and effort involved and demonstrated by these images.  I would have killed to have been able to get one – 1 – image like these.  I would have killed a lot more, to have had the skill to be able to do it repeatedly.

Finally, shelled pteropods, similar to Limacina in some regards, are at the base of the zooplankton food chain throughout much of the world’s ocean.  They are especially abundant in the very rich fishery regions of the cold temperate and boreal seas, where they eat phytoplankton and convert it into their tissue. In turn they are eaten by many other organisms.  Two or three times removed, they are the fish flesh or krill that is harvested for human consumption or use, to say nothing of the top predators in those ecosystems, whose trophic position has been usurped by humans.   These pteropods have aragonitic shells, and as the oceans acidify they will be amongst the first to be affected by this interesting tiny experiment in the alteration of the ocean’s physical parameters.  “Affected” … A nice polite word for “Exterminated” by both human action (the addition of massive amounts of excessive carbon dioxide to the atmosphere) and inaction (no attempt to slow down those additions).

The sheer and utter stupidity of the human species, both individually and collectively is truly mind-boggling.  Here we are, well on our way into the sixth major mass extinction event in the Earth’s existence, and politicians play games of posturing over public images and the majority of the public wastes its time paying attention to the foibles of ephemeral pseudo-entertainer or some ridiculous sporting event.  I guess over the symbolic grave of humanity, our epitaph should be, “Considering their potential and abilities, they had their priorities straight.”

Until later,

Cheers,

Ah, The Good News Just Keeps On Coming…

Thursday, December 9th, 2010

Today’s reading material is by J. E. N. Veron, courtesy of a link in the Yale 360 blog, “Is the end in sight for the world’s coral reefs?”

Of course, the aswer to the question posed in the title to this essay is obvious and is rather succinctly stated by Veron as well:

“It is a difficult idea to fathom. But the science is clear: Unless we change the way we live, the Earth’s coral reefs will be utterly destroyed within our children’s lifetimes.”

Now… for a show of hands… Is there anybody out there that thinks we will change the way we live, 1) at all, or 2) in time to save coral reefs from going the way of the non-avian dinosaurs? 

Hey, its not all bad, we could start a betting pool as to the year or month when the scientists of that future time could declare that the last coral reef finally wasn’t one anymore!

Any regular (if there are any – I really am sorry about the aperiodic nature of the blog, the explantion of that would take too long to write and really isn’t important – but I do hope to do better in the very near future) readers of this impossibly unperiodic electronic space in the aether, have surely noticed my lack of optimism as well.  I think many of scientists who voice public optimism are privately much more “pragmatic” than their public utterances seem to imply and in some – few – cases I have heard about, almost suicidal from the depression and grief of being in the position of observing and documenting this aspect of what is now becoming known in the paleontological community as “The 6th Extinction.”  — The name derives from an examination of the fossil record, wherein there are 5 major extinction events that punctuate the history of life.  On the plus side, so far… life has always recovered and rediversified after these extinction events.  On the negative side, once the cause of the event has been removed, that recovery has always taken tens of millions of years.  Evolution is sure and certain – but to refill a lot of “vacant ecological niches” takes a lot of time.

The positive take is that the changes that occur over the next few decades that will happen should be “interesting.”

And young people today will get to see another interesting phenomenon, where 30 or 40 years from now, new students of marine biology will see this changed (and to my – by then-  long dead eyes) and depauperate, truly ghastly, world as “normal,” the status quo; rather like tourists who now go diving for the first time on (the pathetic algal covered ruins of) what used to be the coral reef at Cozumel or other Caribbean vacation spots, and think they are seeing a thriving coral reef. 

This is what Jeremy Jackson, now one of the “grand old researchers” of the Caribbean coral reefs refered to, in 1997, as “sliding baselines.”  (The underlined emphasis is mine, to emphasize that this has happened to me, too).   

J. B. C. Jackson (1997) Reefs since Columbus. Coral Reefs 16, Suppl.: S23-S32:

 “The problem is that everyone, scientists included, believes that the way things were when they first saw them is natural. However, modern reef ecology only began in the Caribbean, for example, in the late 1950s when enormous changes in coral reef ecosystems had already occurred. The same problem now extends on an even greater scale to the SCUBA diving public, with a whole new generation of sport divers who have never seen a “healthy” reef, even by the standards of the 1960s. Thus there is no public perception of the magnitude of our loss.

 Another insidious consequence of this “shifting baseline syndrome” is a growing ecomanagement culture that accepts the status quo, and fiddles with it under the mantle of experimental design and statistical rigor, without any clear frame of reference of what it is they are trying to manage or conserve.  These are the coral reef equivalents of European “hedgerow ecologists” arguing about the maintenance of diversity in the remnant tangle between fields where once there was only forest.”  

And now, on the cusp of 2011, it is ever so much worse.   We live in a sick world (in all senses of that phrase) run by an aggregration of dunces. 

On that happy note,

Cheers! ??