Dusky Sharks: Whale Killers

It’s generally thought that baleen whales are too large to be successfully attacked by most marine predators.  Orcas are typically considered the only real predatory threat to large whales, and even they have to use teamwork to take down a young whale.  Large sharks, which also sit near the top of the marine food web, are known to scavenge on whale carcasses as a nutritious and blubbery supplement to their usual diet of fishes and smaller marine mammals.  However, evidence has been found that white sharks actually take a proactive approach to increasing the whale carcass supply by attacking live northern right whale calves.  Now researchers in South Africa directly observed dusky sharks actively teaming up to bring down a humpback whale calf.

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Fun Science FRIEDay – Ocean Acidification, More Than Just pH

You have probably heard that as the global climate changes due to human influence the sea surface is going to rise and the oceans will get warmer and more acidic. The bit about the oceans increasing in acidity is particularly troubling because it implies calcium carbonate based organisms (oysters, snails, corals, etc.) will simply dissolve in this future dystopian acid-ocean (that is a bit of an oversimplification, but you get the idea).

Ocean acidity is determined by measuring the pH, which relates acidity based on the number of hydrogen ions found in the water. So long story short, as more and more carbon dioxide (CO2) is emitted into the atmosphere, it in-turn fluxes into the oceans forming carbonic acid which results in the release of hydrogen ions lowering the pH. Simple logic would suggest that this spells bad news for calcifying organism (poor Mr. Snail).

Healthy Pretopod shell (left) and degraded Pteropod shell due to ocean acidification (right). (Photo credit: NOAA [climate.gov])

Healthy Pretopod shell (left) and degraded Pteropod shell due to ocean acidification (right). (Photo credit: NOAA [climate.gov])

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Warg extirpation and the destabilization of eagle colonies in Middle Earth

“Eagles! The eagles are coming!”

Pippin, Return of the King

“I came from the end of bag, but no bag went over me. I am the friend of bears and the guest of eagles. I am Ring-winner and Luckwearer; and I am Barrel-rider.”

Bilbo Bagins, The Hobbit

Truly, in this late age, is there anything left to be said of the Great Eagles of Middle Earth; the Eagles that soar in to lift hapless hobbits to safety or hurl rocks down upon their foe? They seem imbued with nearly limitless capacity to raise heroes from the grasp of certain doom, yet so inconsequential that they are called upon only in moments of least need, like a Mûmakil summoned only to pull an onion cart.

A wild warg makes critical carrion for eager eagles. Screen capture from The Hobbit.

A wild warg makes critical carrion for eager eagles. Screen capture from The Hobbit.

But why should beasts so powerful be used so infrequently, and only at the end of all things? Perhaps we must lift the veil and peer beyond the trope to a phenomena that moves the world in subtle and profound ways. Middle Earth is a changing world, reshaped by the actions of warring armies and rising kingdoms. And one kingdom, above all others, rose to prominence and fell, leaving deep scars in the resilience of Middle Earth ecosystems. The destabilization of Great Eagle colonies is only one of many orcthropogenic impacts to the ecology of realm, and it begins with the extirpation of the wargs.

Ages away, in a less magical time, we can look at the effects of species much like the warg, and how they shape their ecosystems. Across the Great Plains, over the Rocky Mountains, there lies the Fiefdom of the Yellow Stone. And in this place, this Yellowstone, the king of all creatures is the Grey Wolf. The Grey Wolves ruled for many years, until men, jealous of their land and fearful for their flocks sought to drive wolf from Yellowstone. Thus these fearsome keystone predators were extirpated from their home. Yellowstone lay barren of Grey Wolves for many years, until at last, through great effort, they were returned. 

Because grey wolves were both extirpated from and reintroduced to Yellowstone, we can examine their effects on the ecosystem in exquisite detail. One of the more surprising discoveries was just how big a role grey wolves play in provisioning scavengers. Grey wolves often leave large carcasses, and these carcasses make biomass available to other species the thrive in Yellowstone. When grey wolves were extirpated, carrion biomass went down, and carrion species declined. They also acted as a “temporal transport” for biomass–wolves ate less of their kills during the winter, leaving more available to scavengers during lean times. Among these scavengers are the Bald Eagle, whose reproduction is closely tied to available food sources. The fewer carcasses, the fewer eagles.

Return now to Middle Earth, and the great wargs of the Misty Mountains, wolf-like creatures large enough for an orc to ride. Wargs fulfill many of the same roles as wolves in the Middle Earth ecosystem, bringing down large prey and leaving carcasses for others to feed upon. Like the grey wolf, wargs were extirpated during the Third Age–they were captured and domesticated to serve the Mordor war machine. When Thoren Oakenshield and his band fled the Goblin tunnels, they were set upon by goblins and barely-domesticated wargs. When the Fellowship marched, decades later, they saw no wild wargs.

Thus, the domestication of the warg is so complete that they are are no more wild wargs in Middle Earth. At the Battle of Five Armies, there was still enough ecosystem resilience to withstand the gradual removal of wargs, but by the battle of Helms Deep, these magnificent creatures had been fully extirpated for six decades and the environment had fallen apart around them.

Without the massive carrion the wild wargs leave behind, the Great Eagle populations declined. As their numbers dwindle and resources become scarce, eagle colonies destabilize and social hierarchies fall apart.  Without a stable flock, it becomes impossible to orchestrate a mass migration towards the Gate of Mordor to confront their foe. Only a monumental effort by Gandalf the White could convince one small colony to come to his aid, at the last possible moment.

Again, we see how ecosystem changes, in both Middle Earth and our own world, can have significant, unforeseen consequences. Perhaps, with the fall of the Dark Lord, we will see wargs return to their native land and bring balance back to Middle Earth. Then we can count, once again, on the spontaneous magnanimity of wandering eagles to save up from our troubles.

Fun Science FRIEDay – Death Star

Happy Fun Science FRIEDay!

While Ebola wreaks havoc on Homo sapiens in the terrestrial world, there has been an even more virulent disease causing the destruction of a marine animal, the sea star. Today we talk about this deadly condition impacting sea star populations and the recent discovery of just what is causing this affliction.


Royal starfish (Astropecten articulatus) on the beach. (Photo credit: TheMargue - http://www.fotopedia.com/items/flickr-2884079538)

Royal starfish (Astropecten articulatus) on the beach.
(Photo credit: TheMargue – http://www.fotopedia.com/items/flickr-2884079538)

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The next era of ocean exploration begins in Papua New Guinea

An OpenROV at Lake Merrit.

An OpenROV at Lake Merritt. Photo by author.

In 1946, Jacques Yves Cousteau and Émile Gagnan released the Aqualung, forever changing the way humans interact with the oceans. No longer tethered to the surface, entombed in thick, restrictive helmets, we could dive deeper, stay down longer, and explore the dark places snorkelers and free divers feared to fin. The Aqualung opened up the ocean to an entirely new cohort. Ocean exploration, once the domain of well-resourced scientists, career explorers, and the wealthy elite, was now within the reach of the global middle class.

Buoyed by the Aqualung, Marine Science exploded. Marine life could be studied alive and in situ. Behavior could be observed rather than inferred from the stressed and shredded samples of a trawl. The ranks of marine biologists, oceanographers, and explores swelled to numbers that began to gradually approach the relative significance of the ocean to the living world.

We’re just getting started.

Marine science is on the brink of the greatest sea change since JYC and Gagnan introduced the Aqualung to the world.

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Busting Ocean Myths: This anglerfish is not as kink as you think.

The claim: Deep-sea Anglerfish have parasitic dwarf males that fuse to their mates and become nothing more than wibbly gonads hanging off of the much larger female. 

Who said it: Well, pretty much everyone. This Oatmeal Comic, Ze Frankme.

Status: Sometimes true, sometimes false.

Melanocetus johnsonii. Photo by Edith Widder.

Melanocetus johnsonii. Photo by Edith Widder.

cover-Time-19950814-82066I’d like you to meet a very dear friend of mine. This is Melanocetus johnsonii, the humpback anglerfish. If you follow the deep sea at all, you’ve probably met this delightful creature. She was featured on the cover of time magazine, barely losing out to Newt Gingrich for 1995 Vertebrate of the Year. Since then, she has been a standard-bearer for the deep sea, an iconic species, immediately recognizable. Stories of her exploits abound, and no story is more compelling that the tale of the hapless male anglerfish, a parasitic dwarf that lives its entire adult life fused to the larger, more capable female angler fish.

There’s just one problem.

Melanocetus johnsonii, along with the four other anglerfish that make up genus Melanocetus, don’t have parasitic males. Males of this genus are still significantly smaller and lack lures, but they retain their free-swimming lifestyle into adulthood, occasionally biting into the side of a much larger female for a temporary coupling, where gametes and food are exchanged. This temporary coupling, in which no tissue fusion takes place, has been observed only three times: once during the filming of the BBC Blue Planet documentary; once off the coast of Japan; and once, confusingly between a male Melanocetus johnsonii and a completely different species, Centrophryne spinulosa. In none of these instances was the connection permanent, and no reduced males have even been found attached to a Melanocetus. Read More

Fun Science Friday – First Female Penis

Happy Fun Science Friday.

You did not mistakenly read the title, today we bring you the discovery of the first female penis in the animal kingdom.

Mating insects of the genus Neotrogla. Photo Credit: Current Biology / Yoshizawa et al.

Mating insects of the genus Neotrogla.
Photo Credit: Current Biology / Yoshizawa et al.

Yoshizawa, from Hokkaido University in Japan, and his team of researchers documented this phenomenon of sexual role reversal in 4 species of rather unassuming insects in Brazil’s Peruaçu River Valley.  When insects of the genus Neotrogla mate, the female mounts the male and penetrates his vagina-like opening with her penis.

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10 times more fish in the sea? Context matters.

Earlier this year, a research team from Spain released a surprising new estimate of mesopelagic fish biomass that is 10 times greater than previous estimates. This new study raises the total estimated biomass of mesopelagic fish from 1 billion tons to 10 billion tons, accounting for 95% of all fish biomass. The news media ran with dozens of variations on the “plenty of fish in the sea” trope, suggesting that the global fisheries may be more abundant and reversing the doom-and-gloom message of fisheries decline.

This is not correct.

The fish in question are small, mid-water species like myctophids and cyclothones, fish that are incredibly important for ocean ecosystems, but commercially non-viable. The reason they were missed in previous studies is that these small, agile fish avoid nets; This new study uses SONAR and other acoustic tools to measure biomass.  So while there is a huge, untapped fish stock in the mid-water world, it is not a commercial fishery.

Let’s put things in perspective.

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Fun Science Friday – BP Oil Spill Impacts Dolphins

Happy Fun Science Friday!

Though this post does not present such a happy story, given the recent discussion about dolphin photobombing, this week’s FSF is topically related.  In the spring of 2010 the Deepwater Horizon oil rig experienced catastrophic failure resulting in the worst oil spill in human history. The Gulf of Mexico (GoM) was the unfortunate host of this catastrophe and the GoM community is still feeling the ecological, social, and economic consequences of this disaster.

Pod of bottlenose dolphins swimming underneath oily water of Chandeleur Sound, La., May 6, 2010. Photo Credit: Alex Brandon/AP

Pod of bottlenose dolphins swimming underneath oily water of Chandeleur Sound, La., May 6, 2010.
Photo Credit: Alex Brandon/AP

One such impact that received little TV coverage during the spill was the uncharacteristic spike in dolphin deaths. A few months following the BP spill there was an unprecedented spike in dead dolphins washing ashore along the Gulf Coast; 67 dead dolphins by February of 2011, with more than half (35) of the dead dolphins being calves. This is in stark contrast to years preceding the spill when one or two dead dolphins per year were normally documented to wash ashore.  Despite the spike in dolphin deaths, there was no definitive evidence linking the dead cetaceans to the oil spill as a number of other factors could have been responsible for the deaths, including infectious disease or the abnormally cold winter proceeding the spill.

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