Monthly Archives: July 1996

Stinging limu season is here; try to steer clear

Published July 29, 1996 in the “Ocean Watch” column, Honolulu Star-Advertiser ©1996 Susan Scott

STINGING limu season is upon us. A few weeks ago, a dermatologist told me he suspected this seaweed was the cause of a blistering rash on the stomach of a girl swimming off the Waianae Coast. Soon after, the state Health Department received reports of swimmers afflicted with rashes from stinging limu along the Mokapu Peninsula, Kailua Beach and Ewa.

People in Hawaii call a variety of marine organisms stinging limu, but only one true seaweed is known to commonly cause a rash in humans here. This blue-green seaweed, called Lyngbya majuscula (or sometimes Microcoleus lyngbyaceus) usually grows in clumps, looking like dark, matted masses of hair or felt. Most often this seaweed is blackish-green or olive-green, but it also grows in shades of gray, red or yellow.

The filaments of this seaweed grow up to 4 inches long, often tangling with other seaweeds on reef flats, in tide pools or water as deep as 100 feet. When loose in the water, this seaweed looks like floating, tangled strands.

The toxicity of this seaweed varies greatly depending upon region, season, and type. Not all strains of this seaweed are toxic.

WHEN toxic, stinging limu contains two potent, inflammatory toxins, both causing skin damage upon contact. Typically, seaweed fragments get caught inside swimsuits, rubbing these toxins into the skin.

Epidemics of this seaweed-induced rash occasionally occur in both Hawaii and Okinawa. In Hawaii, the highest number of cases occur from June through September in windward swimming areas. Persistent trade winds blowing during these summer months may dislodge the seaweed from the bottom. Fragments then drift into swimming bays and beaches.

The Health Department issues public warnings when outbreaks of this rash occur in swimmers. Heed these warnings. Common areas are Kaneohe Bay, Kailua Bay and waters off Laie and Ewa, but the seaweed grows and drifts in other areas too.

LIMITING swimming time in affected areas does not guarantee protection, nor does the prompt removal of your bathing suit. If you come in contact with the stinging variety of this stuff, you will likely end up with a rash.

Rash victims feel an itching and burning sensation minutes or even up to 24 hours after leaving the water. A red, sometimes blistering rash occurs, sometimes in an entire swimsuit pattern. Most surfers are all too familiar with this seaweed, which can wash down the suit and irritate the most tender of body parts.

Such a rash also can occur on the face and in the eyes and mouth. Some victims have swelling of eyes and mouth, but no rash.

For mild to moderate cases of skin rash, remove your swimsuit immediately and wash skin vigorously with soap and water. Wash the suit, too.

ALTHOUGH unproven, cool compresses or rubbing alcohol may help relieve the pain. For persistent itching or skin rash, doctors recommend trying 1 percent hydrocortisone ointment four times a day, and one or two 25 milligram diphenhydramine (Benadryl) tablets every six hours. These drugs are sold without prescription. Diphenhydramine may cause drowsiness, so don’t drive, swim, or surf after taking it.

Irrigate exposed eyes with tap water for at least 15 minutes. For severe discomfort, blistering not responding to first-aid treatment, eye stings, or any signs of infection, see a doctor.

Any difficulty breathing signals an allergic reaction, which is always a medical emergency.

Other marine organisms, including tiny jellyfish and flatworm larvae, can cause similar-looking skin rashes. Distinguishing these from this seaweed rash often is impossible.

The good news, however, is that treatment is the same.

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


Visit to Lake Michigan yields a good fish tale

Published Jul 22, 1996 in the “Ocean Watch” column, Honolulu Star-Advertiser ©1996 Susan Scott

RECENTLY, I made an unexpected trip to Wisconsin. I wasn’t there two days before I began suffering ocean withdrawal. My skin flaked. My eyes dulled. I missed the sound of surf and the smell of salt air.

“Go visit Lake Michigan,” a family member advised. “It’s kind of like the ocean.”

Yeah, sure, I thought. However, even if I couldn’t get a marine fix, the idea of getting outdoors was appealing. I headed for The Lake.

As soon as I pulled into the parking lot of the harbor, my dehydrated cells perked up. This was salt air if I ever smelled it.

I know. Lake Michigan is fresh water. But honestly, although the temperature was cooler, the air smelled amazingly like the ocean.

I found the answer to this puzzle when I began walking to the lighthouse. On the rocks, and in the surrounding water, were bodies of countless small white fish. Apparently, the odor most of us associate with the ocean is fish.

Those 8- to 10-inch white fish lay dead and dying everywhere, many still twitching. I asked three groups of fishermen about these fish. All agreed that they were called alewives, but each had a different explanation for why they were dying:

  • These saltwater fish migrate from the Atlantic up the St. Lawrence Seaway in springtime, then die when trapped in fresh water.

  • Alewives are cold-water fish that die each year at this time when the water warms up.

  • These fish die each year after spawning, like salmon.

Each explanation seemed reasonable and it turns out that each has its own partial truth. The Lake Michigan alewife story, a park ranger explained later, has an interesting biological history.

Once the lake contained 180 species of fish. Sturgeon, lake trout, herring and pike were among these, thriving in the lake and boiling the bays and shallows with spawning activity in springtime.

Then Europeans arrived and began settling the Lake Michigan region. An enormous logging industry arose and soon, logs and sediment choked every stream, river and bay of the lake. Along with the logging boom came towns. Sewage, industrial wastes and agricultural runoff soon followed. By the early 1900s, algae blooms from the added nutrients had destroyed the lake fishes’ spawning grounds. Native fish populations crashed.

ENTER a few alien species. Carp, brought to ponds for food, escaped into the lake and multiplied. Later, eel-like sea lampreys wiggled their way into the lake through the seaway and took hold, munching on lake trout. By the late 1940s, lampreys were destroying 5 million pounds of lake trout annually, drastically dropping the population.

The scene was set for an invasion of alewives, relatives of herring, which found their way into Lake Michigan from the Atlantic Ocean in 1949. With the decimation of lake trout, the alewives had few predators. By the mid-1960s, alewives made up 90 percent of the lake’s fish by weight, eating zooplankton that ate algae.

THE place, blooming with algae and alewives, was a mess. Water quality was awful. The alewife population peaked in 1966-67, leaving a spring shoreline littered with dead and decaying fish 3 feet high and 20 feet wide. Bulldozers were needed to clear beaches.

The lake began changing in 1972 with the Clean Water Act. Discharges were reduced, a lampricide was discovered, and salmon and trout were introduced to eat the alewives.

Alewives still thrive in the lake today, but in smaller numbers. These adaptable fish, which can survive in either fresh or salt water, spawn in spring in the shallows, where warm water currents from runoff kill the fish each year.

I enjoyed my day at the lake, but nothing can replace Hawaii’s ocean. I can’t wait to get home.

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


Big demand for opihi means few can be found

Published July 15, 1996 in the “Ocean Watch” column, Honolulu Star-Advertiser ©1996 Susan Scott

A recent ad in the newspaper said, “Fresh, frozen opihi from Big Island. $189/gallon.”

Wow! Where did anyone get so many opihi? Whenever I see them, they’re either too small to harvest or they’re stuck to break-neck rocks in pounding surf.

Only once did I see large opihi in accessible abundance, and that was at La Perouse Pinnacles in French Frigate Shoals. This atoll in Hawaii’s northwest chain is part of a national wildlife refuge.

“These fat opihi are driving me crazy,” my snorkeling partner said after we spotted the big snails with the pointy shells crowded along the pinnacles. “Do you think it’s OK to eat just one or two?”

“Better ask the refuge manager,” I said.

“Sorry,” the manager told him a moment later. “Animals are protected here.”

“Even opihi?”

“Even opihi.”

My friend, who relishes every kind of seafood imaginable, was disappointed, but certainly saw the point. The no-harvesting rule was, after all, the reason the opihi were ample here in the first place.

OPIHI are snails that live on wave-swept rocks in intertidal and shallow-water areas. Also called limpets, opihi shells resemble Chinese straw hats. Such broad-based shells offer minimum water resistance to the powerful blasts of water that come regularly from breaking waves.

The strong opihi shells also protect the animal when clamped down on its rock home. And these snails can really hang on tight. Unless you sneak up on these critters when they’re relaxed, there’s little hope of prying them off with bare hands. One local T-shirt says it all: “SUMO OPIHI – Takes a licking and keeps on sticking.”

Those people who know how to pick opihi, however, get an instant treat. Many eat these snails raw, popping the meat into their mouths right at the beach. Because of this, it’s common to see pearly opihi shells lying empty around rocky beaches.

Opihi have been a popular food source in Hawaii for centuries, mostly on windward sides of the islands. (The shells also made useful tools.) Ancient refuse heaps show that opihi made up about 46 percent of the shell composition at windward sites. Leeward sites showed about 5 percent opihi.

Opihi are more abundant on windward coasts because the snails eat the limu (seaweed) that grows on wave-washed rocks.

Although limpets grow throughout the world, Hawaii’s opihi species are only found here. We have four kinds but only two are commonly eaten: the yellow foot (alina’alina) and the black foot (maka’ia’uli). Because the black foot is found higher on the shoreline than the yellow foot, it was traditionally called the lazy man’s opihi.

OPIHI are capable of spawning throughout the year, but most often release eggs and sperm into the water from November to June, when seawater is the coolest. After a few days in the ocean, the baby opihi find and stick to a home rock. The snails spend their entire lives, about a year, grazing that particular area.

Compared with the growth rates of limpets in other parts of the world, opihi grow extremely rapidly. The snails reach sexual maturity when the shell diameter is just under an inch, usually after a few months.

The body weight continues to increase throughout the animal’s life. The longer an opihi is allowed to grow, the greater the weight of its edible meat.

Opihi picking season is year round. Shells must be at least 11/4 inches wide, or the meat a half inch wide, to legally harvest them in Hawaii. Unfortunately, too few people have followed this rule, making opihi relatively scarce today.

Those that are left are usually found in dangerous, hard-to-reach places. Falling and drowning deaths of opihi pickers are all too common in Hawaii news.

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


Humans have decimated pencil urchin population

Published July 8, 1996 in the “Ocean Watch” column, Honolulu Star-Advertiser ©1996 Susan Scott

LAST week, while taking an evening stroll down the outside pier of the Ala Wai Boat Harbor, I spotted a big yellow-and-white catamaran in the transient space. Wondering where it came from, I peeked around its stern to read its home port.

pencilNothing was written there. But what I did see in that boat’s cockpit stopped me in my tracks. Disgusted, I turned to leave, then went back and looked again. Later, I brought a friend there and showed him the sight.

I couldn’t stop thinking about these people’s little collection, and as you can see, I am now even writing about it.

The “it” is this: Two exquisite, fully grown slate pencil urchins, dead as doornails, sat drying on the deck near some fins, masks and snorkels.

Some might argue that perhaps these folks found the urchins already dead on a beach and simply brought them aboard. I have trouble believing that. These urchins hide in cracks and crevices during the day, usually in wave-swept areas. At night, the animals leave their shelters and graze on algae. It’s uncommon for these animals to just drop dead out in the open, then wash ashore fully intact.

More likely, some snorkeler from the boat thought they were pretty, dragged them from their shelters, then killed them by bringing them aboard.

When these urchins dry out more, they turn dark brown, the spines fall off and the whole thing stinks like mad. These sailors will end up with a pile of rotting flesh and drab calcium carbonate paddles for a trophy. Which, no doubt, they will then toss overboard.

OK, so I’m being shrill over a couple of sea urchins. But this kind of thoughtlessness gets my blood pressure up for several reasons. First, it’s one of the things that gives boaters a bad name. These incidents stick in people’s minds, then come up again when boaters ask for favors, such as additional mooring space.

Another reason this incident galls me is that this kind of destruction is so useless. No one wants to eat these animals, and they never cause anyone harm. Yet they are killed by the dozens.

One source says that slate pencil urchins were once common on most of Hawaii’s reefs. Attracted to these animals’ unique shape and color, reef visitors brought them ashore only to later discard them on the beach. The result, of course, is that these urchins are now scarce in all the areas readily accessible to humans.

In ancient Hawaii, people called these urchins punohu and used their spines as pencils. The rust-red color easily rubs off on rocks and slates.

Sea urchins may look like some sort of weird pincushions, but these living, breathing animals are intricate parts of healthy reef ecosystems. They deserve to live.

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


Hawaii’s largest estuary is down but far from out

Published Jul 1, 1996 in the “Ocean Watch” column, Honolulu Star-Advertiser ©1996 Susan Scott

Last month, when a pipeline broke in Pearl Harbor, spilling bunker fuel all over the place, most of the comments I heard fell into one of three categories:

  • Curses on those oil companies.

  • Pearl Harbor is already so polluted, it hardly matters.

  • Huh?

It’s easy to blame oil companies for fossil-fuel pollution problems. They’re big, faceless corporations that everyone loves to hate.

But before cursing Chevron for this recent accident in Pearl Harbor, consider the fact that the offending pipeline was feeding the Waiau power plant, one of three on Oahu providing us with electricity. Each of us uses the product of this pipeline. And no matter how scrupulous the safeguards, accidents happen.

And what about Pearl Harbor itself? Is it already a lost cause?

No. Despite its association with World War II devastation, the Navy and runoff pollution, Pearl Harbor remains alive and kicking. The place may not be pristine, but it has still got plenty of wildlife to root for.

Take fish. Pearl Harbor is home to significant numbers of:

  • aholehole (Hawaiian flagtails)

  • papio (young jacks)

  • awa (milkfish)

  • awaaua (ladyfish)

  • kaku (barracuda)

  • amaama (mullet)

  • oopu (gobies)

Baitfish such as nehu (anchovies) and goldspotted herring also thrive in Pearl Harbor. Fishing boats with special permits regularly enter the estuary to catch these baitfish, important in the aku pole-and-line industry.

Invertebrates flourish in this harbor too. Opae (native shrimp) need this place where fresh and salt water mix. Like the stream gobies, opae life cycles are the reverse of salmon. Both gobies and shrimp spend their adult lives in fresh water, then migrate to salty areas to spawn. Pearl Harbor offers one of the few places left on Oahu where these animals can reproduce.

Pearl Harbor got its name from its abundant pearl oysters, which became scarce at the turn of the century from overharvesting and muddy agricultural runoff. Now oysters, clams and mussels have come back.

Harvesting Pearl Harbor shellfish, however, is strictly prohibited by the state Department of Health. Even in the best of circumstances, these filter-feeding bivalves can contain lethal bacteria and chemicals from fertilizers and pesticides.

And even though Pearl Harbor itself is doing well, it still receives the damaging results of a lot of human activity from up the valley.

Samoan and bluepincer crabs can be found in good numbers in Pearl Harbor these days. Because the Department of Heath no longer has the money to monitor these crabs’ meat, eat them at your own risk.

Crabs are scavengers and will eat just about anything they come across, including the tissue of dead oysters and clams.

Wjp cares if all these shellfish are thriving if we can’t eat them? The endangered waterbirds who live in the wetland refuges there are sensitive to the health of the estuary.

Pearl Harbor houses one of the few wetland nesting areas left on Oahu for native stilts, coots, moorhens and ducks.

Fortunately, the recent oil spill caused no direct wildlife deaths in the harbor.

It did, however, coat the shoreline and intertidal area around Ford Island and the Waipio Peninsula.

The first phase of the oil spill cleanup is ending. Workers are now making restoration plans and setting up systems for monitoring long-term impacts on fish, shellfish and other wildlife.

Pearl Harbor, Hawaii’s largest estuary, certainly is well worth the effort.

Marine biologist Susan Scott writes the newspaper column, “Ocean Watch”,
forthe Honolulu Star-Bulletin,