• introduction:  What makes Goat Island such a special place? Wave regime, currents, diversity of substrate and habitats
• habitats: Wherever the conditions for life change, the opportunities for the living organisms change as well.
• bladder weed zone: The shallow seaweed zone is dominated by tough bladder weeds. Sleeping here is hell but there's a lot of food for grazers.
• barren zone: Sea urchins and other grazers keep a vast area of rock free from large algae.
• kelp forest: The kelp forest is dominated by the Stalked Kelp and it extends down to 18m deep
• deep reef: The deep reef habitat is too deep for the brown and green seaweeds. Fragile animals such as sponges are found here. The sponge garden is a special case of the deep reef habitat.
• sandy bottom: The sandy bottom is a rich feeding ground for bottom-dwelling fish and those reef fish that forage here.

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But having the mainland on one side, providing shelter for winds from the NW to SE, makes the rocky shore here less exposed than that of outlying islands such as the Mokohinau group. These factors together classify it as a medium-exposed reef environment, which means that it is very typical of the North Island's East Coast.

The presence of Goat Island brings shelter to some places, which gives this coast a high diversity in species and sheltered places to work and play. Not entirely by accident, is good access available right where the island is. Geological studies have shown that a fault line has twisted the earth around an axis running through the creek's valley, lifting the Cape up by several metres and in the process perhaps causing Goat Island to emerge from the sea as well. It thus happens that to the West the rocks consist of layered sandstone whereas to the East they consist of the 'mother rock', greywacke. Greywacke was formed from sediments, metamorphosed by pressure and heat, such that its typical layering disappeared. Once situated deep down, it was brought to the surface by tectonic movements. One can never find fossils in them. But right above the greywacke one finds a layer of mixed stones and sandstone, resembling concrete (right at the beach). Here one can find big clams that about one million years ago, inhabited these shores. One can also find the fossilised burrows of ancient heart urchins that once crawled here through the sandy mud.

The two types of rock give rise to two different versions of the exposed rocky shore. To the west, the coast is layered like pancakes. These layers are clearly visible in the weathered cliffs but they extend equally out into the sea, for several hundreds of metres. The soft rock can be burrowed into by boring clams and the sand scours at them as well. These two forces combined create undercuts and overhangs, giving shelter to small creatures such as small fish (spotties and kelpfish) and crustaceans (small crayfish). Waves run over these rock shelves, and while dissipating their energy, make life hard for anything else but tough bladder kelps.

To the east, the rocks consist of hard Greywacke. These rocks tend to crack vertically, giving rise to caves which are not found to the West. The caves and long-lasting tumbled boulders provide good shelter for big fish such as parore, red moki, silver drummer and marblefish and likewise big crayfish. Waves bounce off the steep shore and are reflected back to sea, failing to dissipate their energy. As a result, along this stretch of coast, shelter is soon found in deeper water, reason for big fish such as snapper to hang about on this side of the Reserve. Grazing sea urchins are able to attach themselves firmly to the rock and to graze all plant life down to a mere film of algae that functions as an underwater grassland.

All these conditions together, make Goat Island a very special place. It is in fact so special that no similar place can be found within two hours from Auckland. All the more reason to treat it with respect.

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Habitats The physical conditions responsible for the main habitats are wave action and absorption of light with depth. As one goes deeper, wave action diminishes rapidly, whereas light decreases more gradually. Furthermore, every habitat is influenced by its inhabitants (grazers remove forest and extend the 'grassland'). As one moves behind a rock, one suddenly encounters shelter or light may diminish suddenly. These factors give rise to miniature habitats that may differ strikingly from the main habitats. The diagram illustrates the typical zoning caused by wave action and light absorption for a medium to highly exposed rocky shore.

f022912: habitat zoning around Shag Rock, during high tide. Right on top a barren zone where seaweeds do not survive desiccation during low tide. It is fringed by a narrow band of Xiphophora, then a 2m band of bladder wrack (Carpophyllum maschalocarpum), and below it the stalked kelp (Ecklonia radiata).

f001221: in the shelter of Goat Island, the zoning patterns blur, and one finds seaweeds placed more or less by chance. However, where wave action is dominant, the stronger bladder kelps prevail. Here the bladder wrack grows higher up. Lower down one finds the more fragile featherweed, and the stalked kelp.

A variety of bladder weeds grows in the shallows. Each has its own tolerance to exposure. Most resilient is the wire weed (Carpophyllum angustifolium ), followed by the bladder wrack (Carpophyllum maschalocarpum), then the featherweed (Carpophyllum plumosum) and finally the flexible weed (Carpophyllum flexuosum). The latter is mostly restricted to very sheltered places such as inside harbours, since it can also tolerate dirty water and low light conditions better. On the exposed cliff faces, the flexible weed may be absent altogether and likewise the wire weed may be absent from more sheltered places, or it may grow into bushy forms, which look different.

On the barren rocks (urchin barrens) we find the main shaver, the common (or green) sea urchin (Evechinus chloroticus). Around it but often hidden in crevices, one finds limpets and chitons that graze the surface very smooth. An important grazing snail which can keep areas barren on its own is the Cook's turban shell (Cookia sulcata).

Lower down starts the kelp forest habitat of the stalked kelp (Ecklonia radiata). It descends down to about 18m where the light becomes insufficient for plant growth, and slow growing sponges can compete for space. The depth of the kelp's lower boundary is an indication of average water clarity: the deeper this boundary, the clearer the water is. (Poor Knights 35m)

Ironically, on the East Coast, the sand bottom starts about where the kelp forest ends, leaving very little area for the deep reef habitat of sponges. Only around promontories where currents sweep the sediment away, will enough depth be found for this habitat. Outlying islands such as the Poor Knights and Mokohinau, have a deep sea bottom around them (80m) which allows for a substantial increase in deep reef habitat. Both Goat Island as well as Cape Rodney introduce small areas of deep reef.

The sponge garden habitat is a special case of the deep reef. It occurs on flat rock shelves that may regularly become covered in sand. Plants such as the stalked kelp can't germinate here but sponges can survive periods of being smothered.

The shell trap habitat was not recognised at the time the reserve was established and has been left out as a consequence. Where the rocky shore meets the sandy beach, shells may get piled up during heavy storms, providing a food binge for animals that can also survive the famine in between binges (some snails and starfish). The shallow sand has also another effect, that of scouring. During storms, all surfaces get sandblasted and only some organisms can survive this. In the period of deadly plankton blooms we observed that these heavily scoured areas survived better than elsewhere, as if the sandblasting had an important cleansing effect as well. Note that the deep reef around steep promontories experiences 'ground swell', and receives a similar amount of sand scouring, also to its benefit.

In the El Nino years 1992-1993 New Zealand and particularly the area around Leigh experienced dense and extensive plankton blooms. These were so severe and lasted for so long that the entire kelp forest was killed from Whangarei to Great Barrier Island to Kawau Island to Leigh. In the following years of 1994-1995 plankton blooms kept knocking back whatever recovered but by 1996 a sure and steady recovery was on its way. By the end of 1997 many organisms had returned and it would require a trained eye to see what was still missing, such as old specimens. But the plankton bloom disaster has made huge changes to the zoning under water. As the kelp forest became barren rock, sea urchins wandered off into the deep, leaving their original zone insufficiently grazed. As a result, the kelp forest rebounded here first, where the light is more favourable. In the years following the event, no major storms were experienced to remove the shallow stalked kelp. The situation now is that of hardly any barrens, and extensive kelp forest. Eventually the original situation may return but for the moment the habitat zoning maps of Goat Island are not at all accurate anymore. In the summer of 2003, a similar kelp die-off occurred, but not as severe.

Ironically, the reserve has not completely proceeded from bad to better as one would have expected, although some species have benefited from being left alone (red moki, kelpfish, marblefish, moray eel, conger eel, silver drummer, crayfish), others (snapper, blue cod) benefited mainly because people fed them. Some species have disappeared altogether (bearded mussel, seahorse) while many species have visibly diminished in numbers (global sponges, other sponges, sea squirts, stick bryozoa, hydroid trees, blue maomao, demoiselle, kahawai, pipefish, prickly star, blue penguin).

In the twenty years of its existence, the reserve has not or hardly been monitored. Some work has recently been done on commercial species (snapper, blue cod, crayfish), with mixed results. The bottom line is that very little has been learned from the concept of a no-take marine reserve.

The public, however, has learned to make good use of this magnificent inheritance. In the seventies mainly used for spearfishing, the eighties for research, the nineties have surrendered the reserve to the family. In 1996 the visitor count stood at around 120,000 people per year. They all came to do something that only twenty years ago would have seemed ridiculous, that of watching (and feeding) wild fish. Discovering the diversity of life, its elegant shapes and motions and that it is a lot more intelligent than originally thought, gives people a real buzz. A new era has begun. However, in 2001 the people who administer this reserve, decided to forbid visitors to feed the fishes. As a result, the number of visitors has dropped sharply.

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f028417: a lush stand of wire weed (Carpophyllum angustifolium) is found on the most exposed places, where water runs up and down a sloping reef face.

f000718: a parore in olive coloured skin, strips lush red algae off the rich forest of flapjack (Carpophyllum maschalocarpum).

f001227: full view of a parore (Girella tricuspidata) as it swims by. This one wears its pin-striped business suit, which is one of its most common outfits. They can change their colours to white, black, olive, pin stripe and blotched (pyjamas). more.

f001227: portrait of a young parore, still in its yellowy colours. Parore always seem to smile. Notice its fused teeth, which are ideal for nipping and stripping seaweeds.

f000932: a group of parore feeding on sheltered flapjack kelp. They often do so in the spawning season, in groups, seemingly having delight in flaunting their elegantly moving bodies.

f007721: a large silver drummer (Kyphosus sydneyanus) has left its group of 35 mates for a closer look at the photographer. These fish are shy, and meeting a large group of big ones like this, is a rare event. They feed in a simlar way to parore, preferring areas with strong wave action. more.

f016906: a marblefish (Aplodactylus arctidens) rests on a shelf off Pempheris Point. These fish are very shy, and even after 25 years of protection, do no fully trust divers. Marblefish graze the shallows above the bladder kelp zone.

f030230: the kelpfish (Chironemus marmoratus) is excellently equipped to hold on to its surroundings in fast currents. Its breast fins have five hard fingers and its belly from lower lip to half-way, is rubbery. These fish eat crustaceans, limpets and chitons.

Once the main seaweeds are kept out by the forest-clearing sea urchins, other grazers move in to graze where urchin teeth can't reach. Because this zone is found in shallow depths from 3 to 10m, the sunlight is still bright enough for plants to grow. Instead of large seaweeds (macroalgae), the hairy and single-celled seaweeds (microalgae) grow much faster, rendering the barren zone unintuitively productive. Camouflaged by their coverings of pink paint, several species of snail, limpet and chiton are found here. On these feed others.
 
 

f013229: urchins attacking stalked kelp. Once the kelp starts bleeding, other urchins are attracted by smell. f019724: an urchin has climbed halfway up a stalked kelp where it will bite through the stipe, bringing its crown down. The urchin's five-pronged teeth are only just visible.

f001319: this picture shows many of the grazers of the barren zone. The sea urchins are hiding underneath the ledge, only to come out by night. The top of this shelf contains some bushy pink turf, grazed by two Cooks turban shells. On the pink flats one sees cats eye and top shells, and also radiate limpets. Most others are invisible. Inside the bushy pink turf, lives a rich community of sea slaters.

f001932: near Waterfall Reef, the landscape is indeed barren from below the cliff face at 6m depth to the sand at 15m depth. In this photo the sea urchins are seen clustering together on the sheltered side of a rocky outcrop. Clustering reduces the drag of the water, and protects them from predation. But the leatherjacket hanging above them, nips bits off their spines and tubefeet.

f00090: leatherjackets (Parika scaber) are versatile niche feeders. We like to call them junk food eaters, because they nip a little from many kinds of poisonous animals, like sponges. In this manner they harvest only a little bit from a lot of creatures, so that it seems as if they have no harmful effect on their environment.

f001013: spotties like this male (Notolabrus celidotus), are common in the barren zone, but like leatherjackets, they too are universal feeders, found in all habitats.

f001615: the seven-armed star (Astrostole scabra) is capable of attacking and overwhelming sea urchins. Its extended stomach is large enough to engulf the urchin, and to digest it outside its body. Urchins, however, put up a good fight, stinging the star with their pedicellaria, a kind of tube feet with claws.

f000927: Seven-armed stars come in a variety of colours, from dark brown to grey, light brown to purple.

f019936: a red moki (Cheilodactylus spectabilis) puts its big lips around bushy outgrowths of pink turf to suck their inhabitants out. It does so with a loud sound. The ingested sand is then spilled out through the gill openings, and sea slaters retained.

f020916: a bushy form of the pink paint (Lithothamnion sp.) is found on steep cliffs underneath the bladder kelp zone in exposed water where urchins cannot cling to the rock face.

f007701: snappers visit the barren zone to feed on a variety of items, like sea urchins. Their presence reduces the numbers of sea urchins, allowing the kelps to gain ground.

f022901: a diver gently strokes an orange nipple sponge (Polymastia granulosa), showing that it can retract its nipples, even though it has no muscles. Such large sponges were once common, adding a colourful note to the environment. It is fascinating to consider that this sponge must be able to fend off fouling algae. Perhaps it excretes a kind of weed killing chemical.

f014826: young stalked kelp, having settled inside the urchin habitat, is attacked and eaten. Urchins do so in concerted effort, many hands making work light.

f014826: by standing upright in the deep kelp forest, a diver shows just how tall it grows. This is a healthy forest with a closed canopy, underneath which, it is dark. These plants are all exactly the same age, since the forest was destroyed in 1993 through lack of sunlight.

f016803: after a long period of dense plankton blooms in Nov-Dec 92, the entire kelp forest died from lack of light. The dead plants stood for a few weeks, while nobody noticed their discoloration. Then on 3 Jan 1993, cyclone Ola ripped their dead crowns off. They were pulverised like wet toilet paper, never to be found. It took over 4 years to recover.

f017907: large storms rip kelp plants from places where they cannot hold themselves strongly enough. Plants can get washed up on a beach, and die as food for sand hoppers and slaters, but most remain in hollows of the sea bottom, rolling like large live sausages. This tumble kelp stays alive because it gets everything it needs from the sea water: CO2, nutrients, moisture and light.

f014808: The vast stands of stalked kelp appear to have no grazers, but these round bite holes, caused by butter fish (Odax pullus), can often be found. Butterfish bite a hole in the middle of a leaf, by sucking the leaf between their teeth, and biting a half-round cut-out. In this manner, the strength of the leaf is not affected too much.

f007732: a large male butterfish gives the photographer but one fleeting moment to take a picture. These fish are cunning and shy, targets of spearfishermen for many years. Butterfish live peacefully in harems dominated by a single male. They are also called greenbone for the green colour of their bones.

f001921: it is quite safe underneath the kelp canopy. Here and there one finds highways, frequented by many fish. Here a banded wrasse (Notolabrus fucicola) stands still, surprised by the photographer blocking his path.

f007101: Leatherjackets are found in all habitats, but because they are slow swimmers, prefer the calm places such as the deep reef, and underneath the kelp forest. This is a female leatherjacket.

f019916: the red rock crab (Plagusia capensis) is mainly a plant eater. It is found in most habitats, from tide pools down to the deep reef.

f004811: this photo shows a variety of sponges of the deep reef in the reserve. Top left the crater sponge (Stelletta crater); underneath it a fluffy ball of a deadman's finger soft coral (Alcyonaria sp.), the yellow nipple sponge (Polymastia croceus), red meatball sponges (Aaptos aaptos). Poking out of the sand the spikes of fakir bed sponges (Ciocalypta polymastia) and (Polymastia agglutinans). Orange carpet sponges (Crella sp.) are covering some parts of the rock.

f004812: looking back to the previous situation, from behind the large finger sponge in the background of the picture on left. The orange fingersponge (Raspailia topsenti), underneath two meatball sponges (Aaptos aaptos) and in the background the sponges mentioned in the left-hand photo. A young blue cod swims behind the orange finger sponge.

f017101: where sand occasionally covers rocky platforms, sponges can survive where no other organisms can. The sand here consists of flakes of broken shell. In the centre the orange finger sponge (Raspailia topsenti). At its foot a piece of boring sponge, flanked by a yellow nipple sponge (Polymastia croceus). In the foreground and to the left of the orange fingersponge, a dagger sponge (Axinella sp.). The large yellow boring sponge on left (Cliona cellata) not only carpets the rock, but drills holes in it as well. In this manner it survives sand blasting, which happens here during large storms.

f000125: Orange finger sponges and yellow nipple sponges on a deep reef outcrop. The fish in the background are blue maomao (Scorpis violaceus)

f017104: diver and thin finger sponge (Callyspongia ramosa), growing where once the kelp ended. This sponge came back faster than the kelp, which is still absent from this pinnacle. (April 1998) The thin finger sponge is rather variable in colour, ranging from dirty yellow to light orange and from pink to light purple.

Floor Anthoni shows a deceased thin finger sponge at almost the same place as the photo on left. In January 1993, all these sponges died, including the once orange two-finger sponge (Paraphoxya pulcra) in the right foreground. [Photo Dietmar Polster]

f028304: on the sand, and wherever a hole can be dug, the sand octopus (Octopus gibsii) can be found. Since it changes its surroundings like a builder does, it is easy to find. The sand octopus is brownish white with an orange skin around its suckers. It eats mainly shellfish, which it brings home to break open, hence the many shells around its home. Note that it can change its colour substantially!

f006102: large crayfish are found in the deeper regions of the coast. Here a large one has been tagged with an acoustic pinger, to study how it roams about. The study proved that crayfish do move onto the sand to feed, and back to their shelters. They also migrate seasonally back to shallower water. Should this crayfish moult, it would leave its pinger behind on its old shell. Since large crays moult less frequently than young ones, researchers preferred them for their study.

f006036: a loose family of goatfish (Upeneichthys lineatus) found resting on the sandy bottom. The large one is a spawning male and the one in the foreground a future rival. All the others are females. Each goatfish is born female. The three pale ones in front are last year's recruits, the kiddies. Note how the three mature females take positions close to the spawning male.

f004715: A spawning male goatfish resting on a yellow boring sponge. Goatfish can change their colours in seconds. It took nearly 30 minutes to take this photo, as the fish went pale white, each time the photographer sneaked a little closer. Goatfish used to be found in schools of hundreds in the Goat Island Channel, but they disappeared in the early 90s. A few can still be found. in deeper water

f000821: a mature male blue cod (Parapercis colias) has taken possession of an area of flat sand. In the background a small female. The blue cod around the North Island do not grow as large as those around the South Island.

f017911: the smaller blue cod are all female, shown by their brownish coloration. Blue cod do not belong to the family of cods, but the family of weavers.

f002610: since blue cod do not have swim bladders, they sink to the bottom. Not having a swim bladder allows them to make fast excursions to the surface in their raids on prey. But sitting on the bottom has its problems, like sitting in swirling sand, capable of clogging one's gills. for this reason, these fish often skip breathing like divers do. Now and then, however, they need to catch up with a wide yawn.

f002613: in the final stage of its yawn, the blue cod shows all of its teeth and gill rakers, which are studded with teeth too. Prey is caught and gulped inside its cavernous mouth; then ground to bits with its toothed gill rakers. Notice how it has expanded all its gills too.

f002311: an eagle ray (Myliobatis tenuicaudatus) is resting on the sand in the Goat Island Channel. Notice its head, shoulders, whip tail and little fin. When very young, they have a yellowish to olive colour with blue spots.

f005814: this eagle ray has taken a wary pose by lifting its body partly out of the sand, ready for taking off. Like an air plane, an eagle ray can fly through the water only when water flows both over and under its wings. This is the reason why air planes stand high on their landing gear. Standing high on its landing gear, this ray only needs to lift its wing tips, to become water-borne.

f021005: eagle rays are very gracious swimmers. Notice how this one flies over the sand without even stirring it - a difficult example for divers to follow.

f021002: closeup of a resting eagle ray. Notice its steep forehead.

f002312: Within the marine reserve, the eagle ray's main food source is the sturdy Cooks turban shell (Cookia sulcata). It finds these by smell, often folding its wings double to shuffle inside the narrow gaps between the stalks of the kelp forest. The shell is taken to a pebbly spot, where it is crunched with a loud crack. This photo shows the pearly remains of the cracked shell.

f002215: a short-tailed stingray (Dasyatis brevicaudata) has carefully burrowed herself in the sand. This female is highly pregnant, and will give birth to two fully developed babies, which immediately fend for their own. Amazingly, this 'primitive' cartilageous fish has evolved a method of internal fertilisation and live birth. Some sharks also give birth this way.

f004623: A large porae (Nemadactylus douglasii) stands head-down, digging for food in the sand, while a young snapper carefully watches for spilled morsels. Porae suck up large mouthfuls of sand, in search of hidden worms and sand slaters. They expel the sieved sand from their gills. Porae need clean sand, which unfortunately, is gradually being polluted by mud.

f028310: a sand octopus (Octopus gibbsi) has left its den to forage on the sand. These animals have developed a sense of taste on all of their arms, with which they routinely inspect the environment. The sand octopus feeds mainly on clams. They can smell shells burrowed finger-deep, digging these up by blowing the sand away with their jet pipe.

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