Monthly Archives: November 1997

Sand is the stuff of art, hourglasses and beaches

Published November 24, 1997 in the “Ocean Watch” column, Honolulu Star-Advertiser ©1997 Susan Scott

Last week, I ran across four men who were making a sand castle out of a pile of sand.

Normally, this wouldn’t be worth mentioning except this was a really big castle, about 20 feet tall, and the sand pile was enormous – 50 tons of it to be exact. Also, this sand-castle construction was not at the beach.

I saw it in the middle of Pearlridge Mall.

The men, two from the mainland and two from Canada, are professional artists who travel throughout North America making sand sculptures.

This time, they’re creating what they call an Elves’ Castle, a temporary edifice built especially for the holidays.

Believe me, this is no ordinary sand castle. It’s an amazing work of art that will take weeks to complete.

As I watched the artists work, I wondered if they mixed something special into the sand to hold it all together.

“It’s just plain sand and water,” one man told me. “North Shore sand, I believe.”

I asked what happens when it dries out, and the man gently patted a part of the structure already dry. “It holds together quite well.”

I touched the wall too. Pretty solid. Then I picked up a handful of the fine, dry sand from the floor.

It flowed from my hand like a stream of water.

That’s sand for you. It’s remarkable stuff with unusual physical properties.

And although we usually take it for granted, the behavior of sand has profound effects on our daily lives.

Dry sand, for instance, pours like water through your fingers. Yet, unlike water, it supports your weight when you walk on it at the beach. Add a little water to dry sand and it becomes excellent construction material.

Why does sand stick together so well when wet? The answer is surface tension. When moistened just the right amount, films of water surround each grain of sand. This water forms chemical bonds, much like bridges, that link the grains and hold them together.

Add enough water, though, and the sand will again pour like it did when it was completely dry.

Another interesting characteristic of sand is the hourglass phenomenon.

An hourglass works as a precise measure of time because the pressure at the base of a pile of sand does not increase as the height of the sand increases (unlike liquids or solids).

This means that being buried under 30 feet of sand feels about the same as being buried under 3 feet (given air to breathe, of course). It also means that sand grains will trickle through the narrow opening of an hourglass at a constant rate regardless of how many are left above.

To us Hawaii residents, sand doesn’t usually mean either art or hourglasses – it means the beach. Here are a few facts about sandy beaches:

  • Sand beaches are always in motion, changing with both wave size and wave direction.
  • Big waves move sand seaward; small waves move sand shoreward.
  • Artificial structures interrupt the natural movement of beach sand and thus often cause extensive changes along the shoreline.
  • Natural beach erosion can’t be stopped by seawalls. A seawall may initially protect the land directly behind it but it also increases the backwash strength of waves. This accelerates erosion of the beach directly in front of, and at the sides of, the seawall.
  • If seawalls are extended, erosion continues until finally there is no beach at all – just seawall.

You can watch the Elves Castle at Pearlridge go up from now until its completion on Wednesday.

The castle will stand intact until January. Then it will go back to being single grains of sand somewhere on Oahu.

 

Booby birds bold, funny and unafraid of people

Published November 17, 1997 in the “Ocean Watch” column, Honolulu Star-Advertiser ©1997 Susan Scott

The Seattle Times this month reports that a rare seabird has been spotted in Puget Sound.

This species, never before seen north of San Francisco, has been causing a flutter of excitement around the sound.

Birders there have been traveling to Protection Island, an aptly named national wildlife refuge, to get a glimpse of it.

And that’s not so easy.

Since the island is off limits to people, you have to look for the bird by boat.

What is this rare seabird? Well, it’s no rarity to Hawaii birders and boaters – it’s a brown booby, one of three booby species that nest in the Hawaiian Islands. (The others are red-footed and masked boobies.)

Boobies are high on my list of favorite seabirds because they’re so much fun.

Their behavior is amusing, their calls are silly, and their name puts a smile on nearly everyone’s faces.

Years ago, I wrote an Oceanwatch column about a pair of these seabirds that landed on the deck of our sailboat, midway between Costa Rica and Hawaii.

We welcomed their company and enjoyed their antics.

The day the article came out, I turned to page A2. The headline read, “Two boobies win the hearts of lonely sailors.”

It was changed in the later editions.

Booby birds were given their goofy common name by Spanish sailors who thought the birds’ behavior clownish, bobo in Spanish.

But I wouldn’t call these birds clowns. I’d call them tame.

Since booby birds spend most of their lives at sea and therefore evolved with no land predators, they aren’t afraid of people.

Once, while sailing past Nihoa in extraordinarily rough seas, we had a booby land on top of our furled main sail.

The bird balanced precariously on the wildly rocking boom while trying to hang its head down to look at the two of us sitting in the cockpit. Its bold curiosity was hilarious.

Brown boobies tend to rest on buoys (no grade-school humor intended), making most Hawaii boaters familiar with this species.

When I needed some pictures of brown boobies for a book I was writing, I asked a fisherman friend to take me out the Haleiwa boat channel to search for some.

We didn’t go far. A buoy there was packed with a dozen or so of these goose-sized birds.

Another time, I spotted a brown booby on one of the outside buoys of the Ala Wai boat channel.

“Closer, closer,” I called to my partner who was driving our 37-foot ketch. He got so engrossed in watching the bird, he ran the boat squarely into the buoy.

Brown boobies have a large nesting colony in the Gulf of California, which is where some people speculate the Puget Sound wanderer came from.

It’s possible, however, that it’s one of our own.

Wherever it’s from, there’s one thing I’m sure of: The bird is certain to win the hearts of some not-so-lonely sailors.

The shifting times of sand due to people and nature

Published November 10, 1997 in the “Ocean Watch” column, Honolulu Star-Advertiser ©1997 Susan Scott

I received some interesting questions about sand lately.

One reader, an avid spearfisherman, has observed that parrotfish have become pretty scarce around Oahu over the years.

He asks: Since parrotfish make sand, is their decline in numbers decreasing the amount of sand we have on our beaches?

It’s true that parrotfish make sand. Some parrotfish bite off pieces of dead coral rock (limestone) in order to get the algae growing on it. Other species eat live coral, biting into the limestone skeletons that support the living coral animals. Still others eat algae growing on the surface of the sand, swallowing some sand in the process.

Special bones in the fish’s throat grind up both food and coral rock. The food gets used by the fish’s body; the ground-up coral gets discharged through the anus.

If you go to places where fish are protected, it’s easy to watch both ends of this process in action. While snorkeling in the sanctuary waters of Midway Atoll recently, I watched enormous parrotfish (2 feet long) take noisy bites from living coral.

With loud crunching sounds, they scraped their beaklike teeth over the surface of coral heads, leaving characteristic tooth marks.

At the same time, passing parrotfish excreted clouds of fine, white sand that fell to the reef floor.

So. We know parrotfish make sand. And we also know that fishing has depleted parrotfish stocks in many unprotected areas of Hawaii. It seems obvious then, that a lack of parrotfish means significantly less sand for Hawaii’s beaches.

However, it’s not true. And that’s because ground-up coral makes up such a small proportion of Hawaii’s white beach sand.

In many cases, tiny seashells called foraminifers compose 50 percent of the grains on a Hawaii white sand beach. The other components are snail shells, coralline algae pieces, sea urchin and starfish shells and, running a distant fifth, coral fragments.

In rare cases, at its most concentrated, coral makes up 20 to 25 percent of a white Hawaii beach. On the average local beach, however, the number is less than 10 percent.

So where is all this sand that parrotfish produce?

On the ocean floor. Much of the ground-up coral that comes from parrotfish is so fine and powdery, it rarely reaches shore. Rather, most of it falls into cracks and channels and remains near the reefs.

So, in answer to my reader’s question, depletion of parrotfish doesn’t do much to Hawaii’s beaches, but it does lessen the amount of sand found in and around our reefs. Thus, these fish play an important role in the health of Hawaii’s coral reefs.

Another reader wants to know if the beaches off Aina Haina were ever sandy.

Probably not, at least not since humans have been here.

The Wailupe Peninsula, a residential site seaward of Aina Haina, was once an enormous fishpond.

Ancient Hawaiians built their fishponds in areas where freshwater mixed with salt water, usually meaning some silty runoff from the land. Such conditions often produce muddy shores rather than sandy beaches.

This is true also of Waikiki, where the white sand beaches are mostly man-made.

Sand is periodically trucked there to replace that which is carried away both by water and people.

Beach changes often occur through human interference, but some changes are natural.

During my last trip to French Frigate Shoals, a pristine atoll in Hawaii’s northwest chain, I was shocked to find one of my favorite islands, Whale-Skate, completely gone.

Biologists there assured me it would be back in its own good time, that is, at the whim of ocean currents.

 

Marine biologist Susan Scott writes the newspaper column, “Ocean Watch”,
for the Honolulu Star-Bulletin, www.starbulletin.com

California dreaming — but glad to be back home

Published November 3, 1997 in the “Ocean Watch” column, Honolulu Star-Advertiser ©1997 Susan Scott

I recently returned from a trip to San Francisco, where I spent most of my two weeks wondering why I don’t live there.

I love this place, I told myself as I hung over the railing at Fisherman’s Wharf watching California sea lions rest on the docks. These marine mammals have boldly staked a claim on a portion of the public boat harbor, ignoring passing boats and gawking tourists.

We Hawaii folks are used to tiptoeing around our shy, skittish seals, but California sea lions don’t require such coddling. Instead, these brassy animals constantly test the limits of human tolerance.

“Brawwwwk!” a big guy roars at the people.

Up he rears, brazenly waving his furry head back and forth. You have to admire such pluck.

I have to drag myself from this choice viewing spot to check out a new aquarium down the street. The entrance fee is $13, a bit pricey, I think. Then I get inside.

A worker hands me a page of colorful fish drawings, each numbered, then hangs a compact disk player around my neck and places earphones on my head.

If I’m interested in a fish, I’m to enter its number on the player.

As I’m fiddling with my gear, an elevator, decorated like the interior of a submarine, descends. We’re diving now, my disk tells me.

When the doors open, I discover I am indeed underwater, but in an odd way. I’m inside a glass tube, standing on a conveyor belt that runs through an enormous, busy fish tank.

This is great fun, especially when big sharks and rays pass overhead. I’m especially impressed with my compact disk, which receives signals from various locations and plays appropriate information for wherever I happen to be.

I forge on, renting a car and driving to Point Reyes National Seashore, an hour north of the city.

Once there, I meet a surfer who tells me of a trail that ends in marine heaven: great surf breaks, a harbor seal hangout and tons of seabirds and shorebirds.

I’m there the next morning and find everything he promised.

Harbor seals doze by the dozens, and marine birds entertain me for hours.

I even witness one of nature’s best recycling systems in action: turkey vultures devouring the carcass of a dead seal.

My favorite saltwater experience during this California vacation, though, occurred in the most unlikely of places: Death Valley National Monument, hours from the ocean.

There, a ranger tells of the Death Valley pupfish, a saltwater species that lives only in the park. Over geological time, the fresh water of the area’s former lakes evaporated, eventually forming puddles about as salty as the ocean.

The 2-inch long pupfish was the only fish to adapt and survive.

Off I go to check out Death Valley’s wetlands. Like most park wetlands, the place has a boardwalk with interpretive signs. However, there’s one missing ingredient: water. The place is bone dry.

OK, so it’s their dry season. But that’s what is so amazing about the pupfish. During such dry times, the fish burrow deep into mud formed by underground springs. When winter rains fall and create pools, the fish pop out and reproduce like mad. Come spring, the water evaporates and the little fish head back down.

I didn’t see any pupfish, but knowing they were down there, wallowing in the salty mud, was nearly as good.

I got on the plane to Hawaii a few days ago marveling at my California experiences and wondering if perhaps it’s time to consider a move. Then we landed.

The warm breeze, the flowers, the ocean, the mixed plate of people . . . Oh, it was good.

Traveling, exploring and dreaming is fun, but for me, there will never be a better place to call home than Hawaii.