So, there was this tsunami in Hawaii...

by B. N. Sullivan

Here in Hawaii, the drama began on Friday evening, Feb. 26, 2010, while I was watching the Olympics on television.  As is usually the case when I watch TV in the evening, my mini netbook was on my lap, and I was playing a game on it.  In addition to the game, I had Twitter open in my browser -- not wanting to miss anything that might be happening somewhere in the world.  (I admit it: I'm a breaking news junkie!)

At exactly 8:36 PM Hawaii time, I saw the first mention on Twitter of a huge earthquake off the coast of Chile.  The first report said the magnitude was estimated to be 8.3.  A few minutes later, that estimate was changed to 8.5, and a tsunami warning was issued for Chile and Peru.  Roughly an hour after that, the magnitude of the quake was upped to 8.8, and it was announced that a tsunami had indeed been generated.

That was it for me.  I had no further interest in my game, the Olympics, or anything else on TV, save for the news.  I watched the story develop on TV and on the Web until about 3 AM, when I could stay awake no longer.  But by that time I knew that a tsunami was headed across the Pacific; that an official tsunami warning had been issued for Hawaii; that coastal evacuations would begin at 6 AM; and that the tsunami was projected to reach Hilo minutes after 11AM on Feb. 27.  Believing (correctly, it turned out) that most of my family members and friends on the Big Island already were asleep when the tsunami warning was initiated, I sent tweets and emails to them to give them a heads up about what we all would face when morning came.

Promptly at 6 AM -- right on schedule -- the civil defense sirens along the coast began to wail their warning to those who lived in inundation zones to prepare to evacuate.  The sirens warbled again, each hour on the hour, until 10 AM when roads along the coast, as well as those that led into and out of the inundation zones were closed.  Coastal evacuees traveled inland and upslope; vessels left the harbors and went far out to sea to wait in open water; some small craft were trailered inland for the duration.

We sat tight at our house, not needing to evacuate since we live on a hill at an elevation about 500 feet above sea level.  At 10:30 AM the final warning siren sounded.  I have to admit, it was a bit nerve-wracking.

We watched live coverage of the scene at Hilo Bay.  Everyone was nervous.  After all, the epicenter of the  present quake was very near that of another great quake in 1960, which generated a tsunami that wiped out much of downtown Hilo and claimed 61 lives.  In addition, people of our era have seen vivid images of the Boxing Day Tsunami that followed a huge earthquake off the coast of Sumatra on Dec. 26, 2004, which swept  across the Indian Ocean, killing hundreds of thousands of people.  All of this was on our minds, but no one knew exactly what to expect.

The predicted time of arrival for the tsunami came and went.  The webcam trained on Hilo Bay showed calm water, under a clear blue sky.  Several minutes later, however, the water began to flow out of the harbor into the bay.  As the water receded, the surface roiled, there were ribbons of foam, and the color of the water changed radically from transparent  blue to a very muddy, opaque brown.  Rocks and reeftops that had been submerged were now bared for a moment.  Then the water surged back toward the shore.

This cycle was repeated at least six or seven  times over the next hour and a half or so, and indeed, officials have said that smaller, less noticeable (to casual observers) surges continued for many hours.  When the tsunami warning was lifted, just before 2 PM, evacuees were allowed to return to their homes and businesses along the coast, but the beach parks remained closed.  Everyone was warned not to venture into the ocean, due to the possibility of unpredictable and potentially strong currents.

In Hilo Bay, the largest surge turned out to be just over one meter high.  There was no breaking wave, but the surge did wash over the breakwater, and briefly covered a dock in the harbor.  Although we did not witness it, we heard reports that the tsunami  swelled into the mouths of the two rivers that empty into Hilo Bay, surging upstream and turning the river waters very muddy.  As the mass of sea water pushed into the rivers, it uprooted vegetation along the river banks, and carried it back out to sea, along with rocks and other debris from the river bottoms.  Fortunately, though, the surge was insufficient to cause it to overflow the bay and the harbor to an extent that caused damage.  Hilo was spared, and so were all the other coasts of the Hawaiian Islands.

We don't have tsunami alerts very often, and the number of times a tsunami has reached our shores is relatively small.  Still, there have been several instances in which a tsunami large enough to do damage did come ashore in Hawaii, did cause destruction, and did cause injury and loss of life.  Island residents take tsunami alerts very seriously.

We have warning sirens on all of our coasts, and people know that when the sirens sound, they should immediately head inland and/or upslope and ask questions later!  Indeed, during yesterday's event, there were no reports of people who did not cooperate with the evacuation order.

For more information about the tsunami hazard in Hawaii, visit the Pacific Disaster Center's Tsunami page.  For tsunami alerts and data, visit the Web site of the Pacific Tsunami Warning Center, where you can also sign up for email alerts or subscribe to an RSS feed that will bring you alerts in real time.

Whale Sharks: The biggest fishes in the ocean

by B. N. Sullivan

There are lots of fishes in the sea, but there are none bigger than the Whale Shark (Rhincodon typus). These huge sharks live in tropical waters around the globe, and we have had encounters with them in many locations. Seeing these magnificent animals always is a thrill. Their size -- up to about 40 feet (12 meters) in length --  is impressive, and their grace is almost magical.

Unlike most sharks, Whale Sharks are filter feeders. They feed on krill, algae, plankton, and other small organisms suspended in the water. They take in large gulps of sea water, and sieve out the food as it passes over the denticles that cover their pharynx and gill plates. The water is expelled through the gills, while the filtered-out food remains and is swallowed.

No one knows for sure how long Whale Sharks live, but estimates of the creatures' natural lifespan range from 70 to about 100 years.  Whale Sharks do not reach sexual maturity until they are about 30 years old.  They are ovoviparous: that is, their eggs hatch inside the mother, develop without a placenta, and then emerge as live young.

Whale Sharks are curious and often approach divers and snorkelers to have a look, and will sometimes swim alongside them, but these  sharks are not known to be aggressive.  Encounters with these enormous but docile creatures are a joy for divers.

Here is a video, shot at Christmas Island in the Indian Ocean, that perfectly illustrates the excitement of divers who encounter Whale Sharks in the open water:

If the video does not play or display properly above, click here to view it on YouTube.

If you are interested to learn more about Whale Sharks, we recommend you have a look at this Whale Shark (Rhincodon typus) Issues Paper, from the Australian Dept. of the Environment, Water, Heeritage and the Arts; and the Whale Shark page on the National Geographic Web site.

Staghorn coral (Acropora cervicornis), a threatened species

Acropora cervicornis

by B. N. Sullivan

When we think of endangered or threatened species in the ocean, we usually think of sea turtles, or whales, or certain kinds of fishes.  Unfortunately, populations of some coral species also have been seriously depleted, and some are at risk for extinction.

According to the language of the Endangered Species Act of 1973 (ESA), a species is considered to be 'endangered' if it is in danger of extinction throughout all or a significant portion of its range.  A species is considered 'threatened' if it is likely to become an endangered species within the foreseeable future.

The pretty Staghorn coral (Acropora cervicornis) in the center of the photo above is officially classified as a 'threatened' species.  Acroporid corals like this one are important reef-building corals, and they provide a habitat for fishes and invertebrates..

In the United States, this species is found in the Florida Keys, and along the Atlantic coast of Florida as far north as Boca Raton, but it is absent from U.S. waters in the Gulf of Mexico, according to the National Oceanic and Atmospheric Administration (NOAA).  A. cervicornis does occur in the western Gulf of Mexico, and also in the Bahamas, the Caribbean islands, and Venezuela.

In a few places (very few)  it is still possible to see large stands of this antler-shaped coral, but more often these days, the species exists only as small colonies, like the one in the photo above.  In fact, reef surveys have shown that, since 1980, populations of A. cervicornis have collapsed, declining by up to 98% throughout the range.

So, what is responsible for such a marked decline?  The number one threat to Acroporid corals is White-band Disease, a devastating, rapidly spreading disease that destroys the tissues of the coral.  The cause of White-band Disease is poorly understood, but the results are devastating.

A. cervicornis is "particularly susceptible to damage from sedimentation and is sensitive to temperature and salinity variation," according to NOAA. In addition, NOAA lists hurricanes, increased predation, bleaching, algae overgrowth, and human impacts among the factors that threaten Acroporid corals.

Fortunately, conservation efforts have been initiated to manage and protect what remains of the A. cervicornis population.  In some areas -- such the U.S. Virgin Islands, Puerto Rico, and the Florida Keys National Marine Sanctuary (FKNMS) -- restoration activities also have been undertaken following hurricanes, ship groundings, and the like.  Nevertheless, restoration efforts, such as re-attachment of broken coral fragments and attempts to culture and settle coral larvae, are painstaking and have had limited success.

What you can do:
  • When you snorkel, dive, or go to the beach, NEVER stand on or touch coral.
  • Do not collect coral, dead or alive.  (Federal and State regulations prohibit collection of all soft and hard corals.)
  • Divers should maintain proper buoyancy, be careful not to kick corals when swimming over them, and keep gear items such as hoses, gauges, etc. secured so that they do not drag across the coral.
  • Boaters should use mooring buoys wherever they are available.  If you must anchor, avoid doing so near coral; instead of throwing your anchor, swim it down and place it on sand.
The above rules apply to all corals, of course, not just Acroporid corals.

More information: NOAA Fact Sheet: Atlantic Acropora corals - 2-page 'pdf' file

Mushroom corals: Solitary corals of the Fungiidae family

by B. N. Sullivan

Fungia scutaria
Do the images on this page remind you of mushrooms?  The corals pictured here belong to the Fungiidae family.  Note that the family name has the same word root as the English word 'fungus', and these corals are known by the common name Mushroom Corals.

Although the appearance of these corals may look similar to the underside of a mushroom cap, the resemblance stops there.  These are stony corals; they are not soft.

While most hard coral species live as colonies of  polyps that aggregate and form calcareous structures, most species of corals in the Fungiidae family live as solitary corals rather than as colonies.  In addition to being solitary, most of the corals in this family are free-living -- that is, they are not attached to the substrate.

The photos on this page show two examples of solitary, free-living corals from the Fungiidae family.  Both of these are Indo-Pacific species, widely distributed across the region from the Red Sea in the west, to the islands of the central Pacific.  Both of the corals shown here were photographed in Hawaii.

The image near the top of this page is Fungia scutaria, the most common mushroom coral in Hawaiian waters.  F. scutaria also is the largest of the mushroom corals found in Hawaii.  It typically grows into an oblong or oval shape that can reach a size of about seven inches (18 cm) in length, although most of the individuals we have seen are about half that size.

Cycloseris vaughani
The second photo shows Cycloseris vaughani, a smaller mushroom coral species.  Cycloseris corals are more circular or discoid in shape.  Adults of this species grow to a diameter of about two inches (5 cm).

Both of these species begin the post-larval stage of their lives attached to the substrate by a stem-like structure.  As the juveniles mature and take on their adult form, the stem gradually dissolves, and they become free-living adults.

Mushroom corals usually are found in sandy areas near the base of stands of reef-building corals, and on rubble slopes at  the outer edges of fringing reefs.  They are found less frequently in shallow areas where they would be subject to being tumbled about by waves and surge.  They prefer more sheltered environments.

Mushroom corals are known to feed on plankton and the metabolic by-products of the symbiotic algae that live in their tissues, but a team of Israeli scientists carrying out a reef survey in the Gulf of Aqaba (Red Sea) recently witnessed mushroom corals feeding on -- of all things -- rather large jellyfish!  They documented the species Fungia scruposa feeding on a Moon Jelly (Aurelia aurita). You can read about this amazing discovery in this article (with photos) published by the BBC:  Predatory coral eats jellyfish.

See also: Alamaru, A, et al. (2009). Opportunistic feeding by the fungiid coral Fungia scruposa on the moon jellyfish Aurelia aurita. Coral Reefs. DOI: 10.1007/s00338-009-0507-7

Video: Turtle-watching at Puako, Hawaii

by B. N. Sullivan

I'm traveling on the U.S. mainland right now.  A change of scene can be a good thing, but I do miss the ocean when I'm away from the islands.

This evening I logged on to Twitter to catch up with news from here and there, and what do you suppose I discovered?  Someone I follow on Twitter just happens to be vacationing right now in Puako, Hawaii.  Looks like we have temporarily traded places.  Small world...

Judging by her tweets, Michelle and her family are enjoying their time on the Big Island.  Here is some evidence: a video of Hawaiian Green sea turtles (Chelonia mydas) lazily pottering about in the shallows at Puako, shot by Michelle's son.

If the video does not play or display properly above, click here to view it on YouTube.

Related:  Our page about Hawaiian Green sea turtles, and our page with links to all of our stories, photos, and videos of several sea turtles species.

Sharing Aloha: Hawaii in the spotlight

by B. N. Sullivan

Our blogger friend Evelyn over at Homespun Honolulu regularly hosts the Carnival of Aloha -- a blog carnival celebrating all things Hawaiian.  The theme of the current edition is Preservation and a lot of Aloha, and it is well worth reading.

Topics in the current Carnival of Aloha are diverse, ranging from a thoughtful (and thought-provoking) piece about a visit to an ancient Hawaiian heiau on the Big Island, to reminiscences about a romantic visit to the island of Lanai, to an item about the pineapple fields on Maui.  There are several articles about Hawaiian real estate, including one on the current residential market, another on the foreclosure of Hawaii Raceway Park on Oahu, and an article that describes the home in Kailua used by President Obama's family for their vacations in Hawaii -- with photos of the home's stunning interior and grounds.  (Don't miss that one!)

And yes, our article about the new Hawaii  Marine Debris Action Plan is included, too.

We think there is much in the current Carnival of Aloha that will be of interest to readers of The Right Blue, so we invite you to visit: Preservation and Lots of Aloha Create an Interesting Carnival

One more thing -- speaking of interesting blogs about Hawaii.  We spotted a story about an encounter with dolphins in the wild that we know readers of The Right Blue will enjoy and relate to.   It's a guest post by Lisa Weber on Pua and Keoki's Best Hawaii Vacation blog:  Kayaking with Dolphins, On Their Terms - A Big Island of Hawaii Story

Same or different?

by B. N. Sullivan

This image reminds me of those puzzles: Which one is not like the others?

At first glance, all the fishes in the photo look alike.  They're similarly shaped, their bodies are white with lines, and they all have yellow fins and black trim, including a black bar over the eye.  But if you look more carefully you will notice that there actually are two species of Butterflyfishes swimming together.

The two fishes in the foreground of the photo -- the ones with the black spots near the trailing edge of their dorsal fins and the diagonal lines on their bodies -- are Threadfin Butterflyfish (Chaetodon auriga).

The larger fish in the upper part of the photo is a Lined Butterflyfish (Chaetodon lineolatus).  Note that it has a broad black arc on its back, instead of a spot, and the lines on its body are vertical rather than diagonal.  (And yes, that's another Lined Butterflyfish behind the two Threadfins.)

Both of these are Indo-Pacific species, and they are widely distributed.  We have seen them -- usually in pairs -- in many locations from the Red Sea all the way to Hawaii.  The ones here were photographed in Honaunau Bay, Hawaii.

Earlier we posted close-up images of each of these species.  If you take a look at those earlier photos of the Threadfin Butterflyfish and the Lined Butterflyfish, you will be better able to appreciate the differences in their markings.

So, if you see a pretty Butterflyfish -- white, with lines on its body, and with yellow and black trim -- now you know which details to look for that will distinguish the Threadfin Butterflyfish from the Lined Butterflyfish.