Life Below
Niue has had a thorough buffeting from Cyclone Heta in January 2004, in fact perhaps the worst case recorded in living memory. Where people thought to be safe from the sea, some 25m above sea level, this was proved wrong, even though a disaster of this magnitude may never happen again. Under water, the sea received an equal hiding resulting in totally barren areas, completely stripped of life. But on the very sheltered Western side of the island, cyclones are normal fare, occurring sufficiently frequently to maintain a barren seascape. Yet these barrens are covered in fine algae, growing at maximal rates for the dearth of nutrients dissolved in these ultra-clear waters. The barrens maintain armies of grazers, from tiny snails to nocturnal sea urchins and day-time grazing fish. One could say that they maintain more life than the coral-clad slopes of the other side of the island.
The other side, although not visited by the worst of cyclones, receives continuous buffeting from large ocean swell, propelled by never-ending South-East trade winds experienced as a refreshening cool sea breeze all day and night. We ventured a dive there to bring back unique photos of what the best of Niue under water hopes to offer. Diving here is quite dangerous, being swept to and fro at three times walking speed, swinging ten metres over sharp corals, ready to be ripped to shreds. Fortunately this seascape can also be found in safer waters, near the Matavai Resort (matavai= kingfish Seriola sp).
The photos presented here were all taken in September 2004, about 9 months after Cyclone Heta struck. They hope to give you an impression of what Niue looks like, both above and under water, and how it is recovering. To inform yourself about Niue’s history, geography, geology and much more, visit the extensive section about Niue.
For suggestions and improvements, please e-mail the author.
— Seafriends home — About Niue — Impressions part two –Rev 20051122,20060104,
hurricane damage under water
Broken rocks and corals collect in a gully near Avatele but Heta did not move them. Next cyclone may.
Encrusting corals on red coralline algae show some storm damage but most damage here stems from previous storms.
A rubble canyon ground by rubble. But it collects flying ammunition and thus saves corals elsewhere. By yielding in one place, nature saves the surround.
This patch is criss-cross grazed mainly by urchins. Notice how nature always leaves some standing crop to regenerate the loss quickly. These barrens are very productive.
Rare photos of the inaccessible South-East side of the island between Tepa Point and Limufuafua Point
A rare photo of the exposed SE side shows leathery corals and other corals. The leathery corals do not break or chip easily.
Not touched by cyclones, there is still much barren rock, covered by coralline algae, the plant that grows limestone rock.
any coral sticking out above the rest, risks its life in this wave-pounded environment. It shows that corals can grow tall in-between storms.
Broken corals and empty territory are also found on the ‘good’ SE coast, providing food for grazing fish and snails.
Photos taken near a popular dive spot north of the Matavai Resort
Coral landscape near Matavai shows many healthy corals. Lower down, the wave action is less, allowing brittle plate corals to grow.
The coral scape also shows broken corals and much empty space. The competition for space is not as strong as where waters are warmer with more nutrients.
Deeper than 25m there has been no cyclone damage. Acropora plates dominate the seascape, shading out all smaller corals
An acropora plate coral with its open structure, allowing for more protected surface area for its many little polyps.
The underwater barrens and corals near Avatele, a popular harbour with lagoon and good access to the sea
The sheltered side of a coral bommy shows 50% live corals. Because corals have living algae in their skins, they look drab.
Between Avatele and Matavai, corals become increasingly larger and abundant. This is one of many Acropora antler coral species.
A diver finds slow growing coral under a roof window inside a cave. Such leaves of coral may die back, then grow over the old structures again, for hundreds of years.
Slow growing reddish corals in a roof-lit cave. No signs of cyclone damage on these rather old corals. Red leaf coral, Montipora sp.
Caves and canyons are found everywhere, fun to explore. The ones near Alofi support growth of green algae.
Detailed corals
Brown coral polyps half extended by day to catch the most sunlight. Corals have brown algae in their tissues.
At night the coral polyps compete for space while trying to catch small plankton particles (Favia sp)
By day this encrusting Porites coral has its polyps withdrawn but bright sunlight penetrates. Both Porites and Acropora are found in rockpools as they survive being out of the water for a while.
Detail of acropora plate coral showing how it creates maximal surface area and space in-between for its polyps.
Large disc anemone colony saved from cyclones by a protecting rock stack shown in f044914 above.
Actinodiscus sp.
A purple coral with very small polyps is dying back. The white patch died recently; the green patch may have been caused by Heta
Die-back appears to be common in corals. Here a pink Stylophora coral is invaded by red coralline algae
This fine structured Porites coral offers space to burrowing christmas tree fan worms in all colours. Spirobranchus giganteus
These scratches are bite marks from parrot fish. They are quite rare as parrot fish mainly graze on the algal turf growing on coralline algae
plankton feeding fish
Juvenile banded flag-tails in a small rock pool. Kuhlia taeniura (Cuvier & Valenciennes) or Kuhlia mugil?
Banded flag-tail almost invisible just under the surface near shallow rocks. In the foreground an Achilles tang.
This rock skipper blenny was photographed above water, where it prefers to be. They are so cute. Istiblennius edentulus
This rock skipper blenny was photographed above water, where it prefers to be. They are so cute. Istiblennius edentulus
This purple cardinal fish is out at night to feed on plankton but here it shies away from the diver’s torch
Long-nose butterflyfish can feed from deep narrow holes. Forcipiger flavissimus (Jordan & McGregor, 1898)
A white-tipped soldierfish active by night. Behind it a finelined squirrelfish. Myripristis vittata (Cuvier, 1831)
grazing fish
This convict surgeonfish is named after the stripes found on a convict’s overalls. Acanthurus triostegus (Linnaeus, 1758)
Orange and blue Achilles tang at night keeps its daylight colours while sleeping. Acanthurus Achilles (Shaw)
An exquisitely coloured parrotfish deep asleep. A vast number of different parrotfish are found on Niue.es (Shaw)
Note that the synonym tang for surgeonfish means sharp point or spike, referring to the sharp knives on the sides of their tail stocks.
other fish
The double-bar or double-saddled goatfish is able to feed at night with its taste-sensitive barbels. Paraupeneus bifasciatus (Lacepede, 1801)
This patterned Ambon pufferfish (Ambon toby) wedged itself inside the crack by puffing itself up. Here it will sleep and stay night after night. Canthigaster amboinensis (Bleeker, 1865)
Most fish are plant eaters, scraping algae off the coral rocks. Here one sees various species of surgeonfish and sergeant-majors.
The larger rock pools are tranquil and hold a lot of fish
Sea snakes are very common. This one has folded itself into a shallow hole and is sleeping but even so it must surface now and then for a breath of air
Closeup of a sea snake shows sharp eyesight and very small mouth which can still open wide. It has very small fangs backed by a lot of powerful poison.
invertebrate grazers and detritivores
This spiny snail has a narrow opening to fend predators off. It grazes on the wave-swept coral platforms
Grazing cowries like this one are quite common on the shallow flats, but they are collected for decorative purposes
The most amazing of all survivors is this little black urchin, living in the worst of the wave wash, inside its burrows and trenches. With some difficulty also a limpet (centre-right) and a spined snail (top-left) can be found.
Its back is armoured with thick leathery scales, protecting it against sand blasting and flying debris.
The harmonica sea cucumber shrinks to an insignificant blob by day but extends at night to over one metre in length. It removes detritus from where it lives.
Sea urchins are perhaps the most successful grazers on the barrens of the reefs (Echinometra mathaei)
A long-spined needle urchin out by night. Being able to fold its thin long spines, it can creep into small cracks to sleep by day. Diadema setosum
This tube snail lives in a hollow tube cemented to the rock. It catches plankton but also casts a sticky net to be more effective. It then pulls the net in and gobbles its own web inclusive of plankton particles that stick to it
The tridacna giant clam has a mantle with single-celled plants that grow in sunlight. They provide the clam’s main food. Tridacna maxima.
other invertebrates
A feather star walking on all legs, pushing from behind and pulling from the front, it walks towards bottom left. They can cover 2-5 metres a minute!
This unassuming sea slug is the famous Spanish dancer with its wide wings furled alongside its body. When it swims, it spreads its red wings with white circles, a breathtaking view to behold. Unfortunately, this was the last photo on film. Hexabranchus sanguineus
crustaceans
The weak-shelled shore crab has a beautiful disruptive pattern. It moves very fast with its long legs, both in and out of the water.
Grapsus grapsus tenuicrustatus.
The banded cleaner shrimp lives in pairs for life. During the day they advertise themselves clearly underneath overhangs for their fishy clientele. Stenopus hispidus
Detail of a banded cleaner shrimp. These shrimps are very similar to those found in NZ. It does not risk its life in search of food, because its food is brought towards it as sea lice on the skins of fish.