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 NiueImpressions 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.

Bent steel beam at the foot of Alofi in the Heta-hit depths. Notice the very barren rocks, some recently chipped. Their dark colour is from encrusting algae.

A tree was uprooted and lodged firmly inside this cave, not by Heta but by a previous cyclone.

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.

The ‘barren’ rocks of the NW side are covered in fine algae, scraped off by various grazers. Large scratches by parrotfish, fine scratches by surgeonfish, triangular marks by sea urchins

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.

Healthy corals but not much variety. Wave exposure is one limitation but cool water another, and above all a lack of nutrients, necessary for all life.

Niue’s pristine coast shows healthy corals and aggregations of small fish that live from these.

leathery corals and hard corals in profusion on the coast untouched by cyclones

large giant clams show that exploitation is not a problem on this coast. Note the ridges on the outside of this clam, unaffected by cyclones. Tridacna maxima.

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.

Near the Matavai Resort, coral is still in pretty good state, like these acropora plates. But they quickly dominate the seascape.

Deeper than 25m there has been no cyclone damage. Acropora plates dominate the seascape, shading out all smaller corals

Some coral damage dates back to previous cyclones, while some is recent

A young plate coral growing up and outward. Acropora hyacinthus

An acropora plate coral with its open structure, allowing for more protected surface area for its many little polyps.

The diver sees a variety of corals, small fish and lots of very clear water

A pink branching coral and others. Stylophora sp.

The underwater barrens and corals near Avatele, a popular harbour with lagoon and good access to the sea

Near Avatele, the rocks are visited frequently enough by cyclones, for them to look barren

The sheltered side of a coral bommy shows 50% live corals. Because corals have living algae in their skins, they look drab.

The exposed side of the same bommy shows only 5% of live coral, mostly deeper down.

Between Avatele and Matavai, corals become increasingly larger and abundant. This is one of many Acropora antler coral species.

This insignificant seaweed is hardy enough to grow in the wave-washed zone. It is tough as boots.

Nearly all seaweeds reproduce asexually by forming spreading networks of turfing roots

This red turfing seaweed is highly successful but is somehow not eaten

Near Alofi this white mushroom seaweed can be found. It is not eaten by the many grazers.

Inside a dark canyon under a foam umbrella, coral can grow only slowly as also the red coralline algae. Surgeonfish hang around to keep this environment clean.

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.

Where it becomes pitch dark, the night shift sleeps like these red squirrel fish. This photo was taken with preset distance and other settings, pointing the camera into a dark hole. Sargocentron spiniferum

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)

Closeup of brain coral, Leptoria sp.

During the day the polyps hide deep between the hard protecting ribs

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 coral shows complicated structure and small polyps. This coral follows a complicated growth pattern by which it eventually forms a mushrooming plate above other corals

Detail of acropora plate coral showing how it creates maximal surface area and space in-between for its polyps.

A type of honeycomb coral extends its tissues by day but retracts its tentacles.
Favia sp.

Closeup of an unidentified coral with a smooth surface.

Remarkable structure of an unknown coral

Antler type Acropora coral

Anemone-like coral thrives in dark places. Turret coral Tubastrea sp. No algae in its tissues!

An anemone living like a coral in symbiosis with brown algal cells in its skin. Actinodiscus sp.

Large disc anemone colony saved from cyclones by a protecting rock stack shown in f044914 above.
Actinodiscus sp.

 

The coral on left was touched and it retracted its polyps. The one on right did not notice (Cladiella australis)

Two leathery corals, one with its long polyps out. Sarcophyton elegans.

This leathery coral has large polyps.
Sarcophyton elegans.

Coral dying (bleaching) from living (brown) to dead (white) and invaded by green algae (greenish). Porites 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

A brain coral dying back. Yet these waters are unpolluted and cool.

Acropora table coral – dead or alive?

Die-back appears to be common in corals. Here a pink Stylophora coral is invaded by red coralline algae

A diver holds wandering slipper mushroom coral for size comparison.  Slipper coral Herpolitha sp.

Wandering slipper coral is not attached. Storms keep it moving and on top of others. It is a good survival strategy. They can even lift themselves up.

A diver demonstrates size and shape of a wandering slipper coral. By night it extends long polyps.

This fine structured Porites coral offers space to burrowing christmas tree fan worms in all colours. Spirobranchus giganteus

A massive boulder star coral remains unscathed from the storm.
Astreopora sp.

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.

Banded flag-tail are almost invisible, but so are the pipers and grey mullets.

Black and white basslet looks like snow when schooling.

These small basslets are found even in very small rock pools. In the back lives a moray eel.

The most prominent fish of Niue is perhaps this tiny rock skipping blenny, living half out of the water. It can move very fast bent in this u-shape which forms two legs: head and tail. Istiblennius edentulus

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

Two blennies side by side, related to the rock skipper (male and female?). Little fish like these may well be endemic, which means they are found nowhere else but around Niue

Two blennies of different kind sharing a burrow to watch the photographer. They are so cute.

This purple cardinal fish is out at night to feed on plankton but here it shies away from the diver’s torch

Four-spot butterfly fish (Chaetodon quadrimaculatus)

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)

A fine-lined squirrelfish, actively feeding on plankton by night. It has a long anal fin.
Sargocentron microstoma (Guenther, 1859)

A delicately tailed demoiselle or damselfish.

A blue spotted trevally looks almost invisible in the clear water. Blue jack,
Caranx melampygus

grazing fish

This convict surgeonfish is named after the stripes found on a convict’s overalls. Acanthurus triostegus (Linnaeus, 1758)

Convict surgeonfish in pyjamas, shows blotches on its sides

Surgeon fishes are some of the gaudiest coloured fishes on the reef. They graze by day and sleep at night. Acanthurus sp.

A beautiful speckled surgeonfish photographed at night. Acanthurus guttatus (Bloch & Scheider)

Speckled surgeon fish at night Acanthurus guttatus

A school of speckled surgeonfish patrolling the shallows for grazing their fluffy algae

Deep blue velvet surgeon fish by night. Acanthurus nigricans (Acanthurus aliala)

Orange and blue Achilles tang at night keeps its daylight colours while sleeping. Acanthurus Achilles (Shaw)

Orange/blue Achilles surgeonfishes interacting with the divers, being both curious and wary.

Parrotfishes are large and shy by day, but by night they are deep asleep in narrow caves

An exquisitely coloured parrotfish deep asleep. A vast number of different parrotfish are found on Niue.es (Shaw)

Typical parrot fish gauge marks in soft rock

These wild sergeant-major fish became tame within minutes of being fed. Abudefduf sordidus

Juvenile blackspot sergeant-major fish.
Abudefduf sordidus
(Forsskael, 1775)

All sergeant-major fish are industrious grazers on the shallow coral flats. Abudefduf septemfasciatus (Cuvier, 1830)

Moorish idols are also plant eaters.  Zanclus cornutus (Linnaeus, 1758)

Moorish idols seek company in pairs or small groups

Brassy drummers are plant eaters. Kyphosus vaigiensis (Quoy & Gaimard, 1824)

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)

A yellow-finned, gold-lined goatfish at night. Mulloidichthys auriflamma (Forskael)

Boomerang triggerfish or keel triggerfish.
Sufflamen bursa
(Bloch & Scheider, 1801)

Pennant bannerfish. Heniochus chrysostomus (Cuvier, 1831)

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)

The black-spotted pufferfish is one of the most endearing creatures on the reef. It is variable in colour an can change colour at will

Detail of black-spotted pufferfish.
Arothron nigropunctatus
(Bloch & Scheider, 1801)

Black spotted pufferfish occurs in many colours from pale to brown and yellow

Little pufferfish are easily approached by night

Tiny black spotted pufferfish in the hand. Arothron nigropunctatus

Pufferfish wedge themselves into a cosy spot and inflate for a good night’s sleep

This common lion fish is dark brown. Lion fish, also called firefish, can deliver painful stings with their back spines

Closeup of brown common lion fish.
Pterois volitans

A young brown common lion fish

A rare peacock flounder in Avatele harbour. There is little sandy habitat, but this flounder changes its colours as it moves over various rock forms, and is fascinating to watch. Here it has its swimsuit on, pale with blue flowers. Bothus mancus (Brousonet, 1782)

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

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.

Closeup of sea snake

A small octopus withdraws into its den. Notice the many grazing snails.

This spotted rock cod is a small grouper.
Epinephelus hexagonatus (Bloch & Scheider)

Banded moray eel enjoys protection because it looks somewhat like a poisonous sea snake (Gymnothorax rueppellii)

This white spotted brown moray is a white-mouth moray. Gymnothorax meleagris

A well-camouflaged large octopus at night

invertebrate grazers and detritivores

This spiny snail has a narrow opening to fend predators off. It grazes on the wave-swept coral platforms

Don’t step on this sharp snail that grazes in the most wave-washed places

This beautiful cowry actively grazes in deeper water by night. Cypraea sp.

Underneath, this cowry shows fine colour patterns around its narrow opening

Grazing cowries like this one are quite common on the shallow flats, but they are collected for decorative purposes

Don’t step on this sturdy little grazing snail, little bigger than a thumb nail.

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.

This fluffy sea cucumber comes out at night to lick the rocks clean (Stichopus horrens)

On of the most amazing creatures is this large armoured sea cucumber, growing to almost one metre long.

A diver holds an armoured ‘pineapple’ sea cucumber for size.
Thelenota ananas

Diver holding a medium sized armoured sea cucumbe

Detail of the rear of an armoured sea cucumber, Thelenota ananas

Detail of the front of an armoured sea cucumber

Diver finds a large armoured sea cucumber

Thousands of tube feet give it secure holdfast against storms

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.

Mouth of a harmonica sea cucumber, removing detritus.
Opheodesoma australiensis

Sea urchins are perhaps the most successful grazers on the barrens of the reefs (Echinometra mathaei)

A tiny needle urchin has left its hideout to graze at night (Echinothrix calamaris)

A black robust needle urchin is one of the largest urchins on the grazed barrens

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

White spined needle urchin (Echinothrix calamaris)

Hollow-spined needle urchin comes out only by night (Echinothrix calamaris)

Closeup of hollow-spined needle urchin shows anal sac (Echinothrix calamaris)

Hollow-spined needle urchin (Echinothrix calamaris)

Hollow-spined needle urchin folded its spines for least water drag (Echinothrix calamaris)

A short-spined purple/orange urchin appears to read the latest news (Tripneustes gratilla)

Sea urchins survive hurricanes inside the holes they dig

A colony of needle urchins thriving in the worst of a rubble gully

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

Detail of the tube of a tube snail (Dendropoma maxima)

The giant clam filters seawater for fine plankton. It is sought after because it contains much tasty flesh which can be removed easily without removing the  heavy shell, locked into the coral matrix. Tridacna maxima

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

This dense feather star comes out by night where it seeks a position in the current.

Detail of a feather star does not quite show its very fine tube feet

This species of feather star does not move much and is out by day

This feather star hides by day. By night it coils up in the glaring dive light

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!

A baby featherstar grows its arms one by one as it matures.

A deep red serpent star on a purple coral is regrowing some of its arms. Leiaster speciosus

Detail of a red serpent star. Leiaster speciosus

Christmas tree fan worms have delicate double spirals and a closing disc. Spirobranchus giganteus

Gaudily coloured christmas tree fan worms. Spirobranchus giganteus

Christmas tree fan worms by night over a host coral with extended polyps
Spirobranchus giganteus

One can never get enough of christmas tree fan worms

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 juvenile weak-shelled shore crab is almost invisible.
Grapsus grapsus tenuicrustatus

A small crab species, living in pairs along the high tide mark.
Plagusia depressa tuberculata. All crabs, shrimps and crayfish carry their eggs until they hatch, which helps survival.

One of many swim crabs by night.
Portunus granulatus?

A side-spined paddle crab at night.
Charibdis sp?

This flat crab colours well with its protective host, a hollow spined needle urchin. Percnon planissimum

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.

Banded cleaner shrimp in full glory. Stenopus hispidus

This red cleaning shrimp usually lives near eels and cleans them while sharing in their food

A large-clawed hermit crab has collected anemones to protect its soft abdomen. Dardanus gemmatus

Because its house is so light, this anemone-covered hermit crab is able to make away fast

A very pretty white-and-pink feeler crayfish. Panulirus panversicolor. The French call it a white mustache. their food

The common green rocklobster is sought after for food. They can congregate in some caves, jealously kept secret by villagers.
Panulirus penicillatus