Wednesday, August 18, 2010



'He shows no false heroics where sharks are concerned,” I thought, arriving at the skiff before Walt.

On our way back to El Torito from a dive with a horde of sharks, as I discussed the Lord Howe lagoon scene with our skipper Dr Walter Starck, something started to happen for me. After each dive I now had somebody learned to discuss things with: the patterns of life on a coral reef must be susceptible to reason. I could pose questions, test theories and draw on Walt’s vast experience over coral reefs in all the world’s oceans. We were surprised at the extent of lush algal growth on the reef, mainly red and brown seaweeds; they covered about 80% of all available surfaces but there were few tall, foliose sealants, as in cooler seas. On a coral reef such development of algae is amazing. This was another aspect of its southerly location: southernmost coral ref in the world.
On a tropical coral reef conditions lend themselves to an even greater variety of fish species than in cooler waters and the largest proportion of them are herbivores. For this reason the algal growth on coral reefs rarely develops beyond a thin surface fuzz or stubble before being grazed off. Walt said that as an experiment Dr Jack Randall had once fenced off a section of a coral reef so that nothing could graze there; he was surprised at the rapid and vigorous development of seaweeds within the enclosure. So it seems the reason for the profusion of seaweeds at Lord Howe in comparison with other coral reefs is that algae are limited by herbivores of which there are fewer at Lord Howe. Paradoxically they are more abundant where their food stock is less apparent.

I remarked on the number of fish species I had seen which were much bigger than the same species sighted in other areas. Again it could be explained by the peculiar
situation: here we had temperate water fishes at the respective limits of their range.

In such a marginal area a warm water species may find its food exceptionally abundant, as was the algae, while its normal predators and competitors are absent. As I dived around the lagoon I was fascinated by all the extensive efforts which tropical fishes make to avoid predation.

With the incoming tides through the passes fishes begin to move around and schools of dreamfish or drummers Kyphosus fuscus dash about feeding on the weed-covered rocks in the shallows.

Schooling is one way of gaining protection, but predation still occurs at a reduced rate, weeding out the slowest and least healthy. Acanthurids or surgeonfish are schooling herbivores. I watched them swooping down, feeding momentarily like a flock of sparrows, then swirling away up into the water column and defaecating in unison.

In one area a colony of sabre-tooth blennies, Plagiotremus kept plaguing the surgeonfishes. Every time they swooped down to feed these vicious little sea gnats would attack a fin, tearing off a morsel and then diving for cover.

Over flat areas in the lagoon dense swarms of Plotosus catfishes, seethed over the bottom. Besides the protection their school offered, each was equipped with poisonous dorsal spines. With electric vigour their cat’s whisker barbels twisted and probed the bottom. Equipped with taste buds these organs stirred up storm clouds of sand and mud wherever the fishes searched for tiny food particles. Where loose weed patches occurred they wriggled through it. In the process I saw one get left behind as the others moved away some four meters distance. Once he became aware he was alone his whole behaviour pattern changed. No longer protected by the anonymity of the school, he could easily be singled out by predator. He knew it. Frantically he searched for the group, darting headlong and blindly through the weed clouds but to no avail. Even when in the open he could not discern his tribe a few metres away but just charged to and fro in utter panic, eventually hiding himself completely in a weed patch.

On a night dive in the area I found that the school had broken up. The daytime colour pattern: a horizontal white lateral line on a chocolate brown body, was replaced by a series of vertical white bars and the catfishes lay drowsily beneath coral ledges alone.

Just inside North West lagoon pass is the wreck of a trawler, the “Favourite". Among its buckled plates and twisted pipes a score of lionfishes, Pterois volitans, stalk their prey: crabs and tiny fishes. Quite unafraid they will often allow the photographer to approach within a half a meter. Such well-protected species have little reason to fear- their dorsal spines are equipped with effective venom glands. As a warning signal to intending predators their bodies are vividly patterned with red and white vertical bonds and their eyes are concealed with disruptive patterns, to deceive their prey. They hope to creep close enough to gulp them down.

Beneath my mask the sand explodes - a lizardfish dives into a ripple ridge. With a gulping action, alternately flapping gill covers-and opening its mouth, it disappears until only the small snout and eyes are visible. Safe from attackers it lies there until a small fish strays near its capacious, rat-trap jaws.

Within the long. needle sharp spines of the black Diadema sea urchin tiny night-feeding apogonid cardinal fishes hover. To maximise its size a juvenile magpie morwong Gonistius bizonarius, swims with its spiny dorsal fin erect all the time. The adult fish only assumes this posture when threatened or while resting at night beneath a rock ledge.

I chased a shadow of a large fish into a narrow cave. At the very back in the gloom I thought I had him nicely bottled up for a photo. Suddenly I saw a whiptail lashing around and a sharp serrated spine close to my face: it was a stingray ready to defend itself.

In Sylph's Hole tiny Petrocirtes blennies rear curiously like genies from bottles above the - shells of heart urchins. When I approached they darted inside where they have a brood of eggs to guard.
Such is the drive for some form of protection that strange species from warmer waters which normally swim in schools, had formed a group which sand fossicked together: a heterogeneous collection of several goatfish species and a snapper-like Lethrinid.

Often the camouflage method of protection may also serve to conceal a predator when hunting: I watched a large saddled grouper, Epinephelus damelii stalking fishes across the bottom. In the weed his body was green. As he glided out over white sand it blanched visibly. Tiny sabre-tooth blennies kept attacking his flanks. He seemed quite nonchalant, intent on his prey. Then suddenly he turned and snapped at an irritating blenny.

When confronted by a threat to life, each species has adopted some form of protection, or device for gaining time but the mode must also be adapted to its lifestyle. The school makes it difficult for a predator to select and attack an individual: seaweed-grazing fishes and grass eating mammals alike find aggregation a useful protection. But for the fish which stalks its prey alone, camouflage may serve both as protection and a hunting aid. Still other species, equipped with outstanding effective defensive weapons may adopt a slow moving life style and warning colours to discourage attackers.

Over lunch fish scientist supreme Jack Randall from Honolulu told us of the dilemma which haunts him: the 'Last Fish Syndrome". He’s down at 180 feet. His air supply is getting low. He sees a new species of fish. “Catching a new species.” says Jack “is almost as good as an orgasm.”

There's a bull shark sweeping in so close Jack can see two remora clearly visible on its underside as it passes. Jack makes an instant decision. The wrong one. H e decides he has just time left to make a kill shot and it will be O.K. A new species but, straining at his faltering air supply he errs and just wounds the fish, which the shark devours under Jack’s nose. Poor Jack is furious. He has had this experience repeatedly. Any normal diver would have met his death in such situations but, for the past 26 years Jack has been getting away with it, in every ocean and almost every sea on earth.

A dilemma faced me too: what do you do when thirty people with cameras suddenly interrupt you having a crap? It happened this way. Some female visitor to the ship had unwittingly sabotaged the ship’s plumbing. Walt hadn't designed the system to handle sanitary pads. To take pressure of the repair job, Walt had suggested we bypass the system and use the stern platform. Since the ship was moored with her stern facing out to sea, this was no problem and one rather enjoyed the quiet communion with the lagoon and the reef, the sea and the sky. Until that faecal moment when I was caught in the act: a tourist launch suddenly came around the ship; our generator easily masked the sound of its motor. A party of damned rubber neckers making a special trip to see the strange white research ship and all its peculiar equipment. They had already taken snaps of the yellow submarine and the deck chambers. And now, at the stem all I could do, my clothes being high and dry on deck, was stand up and give them a friendly wave.

Walt told me later that the same thing had happened in Miami when his Mayan Indian deckhand, Raphael was caught in the same situation as a three deck ferry boat packed with tourists chugged by.

Next day an unusual encounter with a school of sharks was to teach me another aspect of the predator/prey problem: when man enters the sea he becomes part of its life patterns and may find the best protection by following the methods which fishes have evolved. We began experimenting with the banded pattern on our wetsuits emulating the pilotfish, lionfish and the sergeant major damselfish…

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