underwater photos of underwater habitats and seascapes
By Floor Anthoni (2006)
All images A5 unless further indicated
One of the main attractions of diving in cool temperate waters, is
the capriciousness of the seascape. Whereas tropical coral reefs are quite
monotonous, temperate seas offer a great variety of habitat, varying from
plants to animals and flat sea bottom to steep rocks with caves. On this
page you will see only some of this great variety.
f020518: The deep reef of the Poor Knights, at 40m depth,
enjoys clear and tranquil water. The rocks are not grazed by urchins, which
allows carpet sponges to bulk up, and sensitive, long-lived creatures to
f020519: closeup of the bead coral (Primnoides sp.),
which always grows perpendicular to the currents.
f020516: the deep reef community at the Poor Knights. Primnoides,
carpet sponges and yellow geodesic dome sponges.
f029908: these sensitive gorgoneans are found in relatively
shallow waters, under overhangs. The top left in this picture is still
within reach of grazing urchins.
f029918: at the boundary of the kelp forest, around 30m depth,
the rocks are but occasionally grazed, allowing a patchwork of colourful
carpet sponges to grow.
f029924: on a shaded vertical wall, the community that normally
lives underneath the kelp forest, could be photographed.
f030621: the purple urchin (Centrostephanus rodgersi)
is a powerful grazer, but not as meticulous as the common urchin. As a
result, carpet sponges can just survive.
This urchin is happy with the shaded habitat, which is
not preferred by the common urchin.
f023025: a snorkeldiver shows the dimensions of this shallow
habitat found on sheltered steep walls. It is occasionally grazed by the
common urchin, but a storm sends these back to the deep, allowing fast
growing algae like sea lettuce to flourish.
f029907: under a sheltered overhang, exposed to currents,
one may find this community of fragile organisms, bryozoa, nudibranchs
and gorgoneans. The experience is almost impossible to catch in a single
photograph. (above Bernie's Cave)
f028417: the wire weed (Carpophyllum angustifolium)
is characteristic of the highly exposed rocky shore. At the Poor Knights
it may be found to depths of six metres, where no other seaweed can hold.
Divers find this weed as strong as Number Eight fencing wire, a New Zealand
f007205: Mayor Island has perhaps the most varied community
of seaweeds along the North Island. This picture shows the shallow bladderkelp
habitat, where also Xiphophora, Vidalia and sea lettuce are
f007206: another picture of the shallow water habitat at
Mayor Island. [A6]
f007210: because of wave action, urchins (see centre) cannot
reach the top of this pinnacle frequently, thereby allowing sea lettuce
to grow in abundance. Normally this weed is grazed fiercely by plant eating
fish, but around Mayor Island, most fish have been caught.
f006837: a boulder-strewn habitat like this is a minefield
for sea urchins, who find it difficult to navigate. It invites kelp to
grow where a barren zone is expected. The boulders also house young crayfish
as seen bottom left.
f022912: this picture shows habitat zoning in a moderately
exposed area. Because of the steepness of the rocks, urchins cannot hold
there, and the barren zone between the bladderkelps (C. maschalocarpum)
on top and the stalked kelp below, is not present.
f022235: a young snapper peeps out between a gap in the rocks.
In the past, this rock was covered in red Vidalia but it disappeared
as the environment degraded slowly.
f001921: A banded wrass finds its highway under the kelp
blocked by the photographer. The topography underneath the kelp forest
allows for highways, taken by fish.
For the barren urchin-grazed habitat, see the document on urchins.
f017101: the deep reef habitat extends down from 18m. The
sponge flats occur where sand occasionally blankets the flat rocks, making
it difficult for plants to settle. Almost everywhere in the reserve, the
sponge habitat has been degrading, except where wave action, combined with
sand, scours the rocks. In this photo two species of orange finger sponge
(Raspailia topsenti, Axinella sp.), the dark pink meatball
sponge (Aaptos aaptos), yellow nipple sponge (Polymastia ramosa?)
and the boring sponge (Cliona cellata) in the background.
f000125: orange finger sponges and yellow nipple sponges
on a seemingly barren reef. The deep reef is denser where the currents
f001811: a tranquil moment enjoyed by many species in profusion.
Juvenile fish abound. Such sights have become rare. Spotty and parore in
the foreground. Young snapper on right and young trevally on left. [A6]
f022801: caves are important habitats for the night shift,
here represented by bigeyes on top and slender roughies, almost invisible,
near the bottom. Caves are also important for red moki.
f013414: inside the Hauraki Gulf, the rocky shores are more
sheltered by the protection of Little and Great Barrier Islands. Here one
finds the sheltered reef, recognisable by different species and different
growth forms. This kelp garden consists of the featherweed (Carpophyllum
plumosum), which has various growth forms, like this broad-leaved one.
f005118: In the shallows, spotties abound and in the wave
zone, the bladder kelp (Carpophyllum maschalocarpum) prevails. The
environment is stressed by sediments and dense plankton blooms.
f005104: the long-leaved flexible weed (Carpophyllum flexuosum)
grows tall in rather murky conditions, where other kelps can't survive.
The flexible weed can remove the muck on its leaves by secreting slime.
Here it is seen towering above the stalked kelp, which it will eventually
shade out. It provides protection for huundreds of young spotties.
f004909: where some wave action remains, the flexible weed
is trimmed to stay short, letting light in for this photograph. Carpet
sponges like Crella can only just survive here.
f005103: sediment-covered flexible weed is a nursery for
a profusion of young spotties. Notolabrus celidotus
f017317: because the murky water rapidly absorbs all light,
the deep reef starts at 6-10m. Here is enough wave action to keep the sponges
clean. Deeper down, only muddy rock is found. In the centre an orange crust
sponge (Crella), and in the distance orange finger sponges (Raspailia
topsenti) The yellow nipple sponges are various Polymastia species.
f017316: this photo shows the stress suffered by sponges
in these degrading habitats, but fortunately an army of sea cucumbers
(Stichopus mollis) cleans them with their ten sticky mops. The large
yellow-orange boring sponge (Cliona cellata) clearly shows
where it has been cleaned. In the foreground a nipple sponge (Polymastia
hirsuta) and a pink golfball sponge (Tethya ingalli).
Unfortunately, sea cucumbers are now harvested for human food.
f017315: sediment-covered orange golfball sponges (Tethya
aurantium) showing where a sea cucumber has cleaned them.
f004933: A sea cucumber has climbed an orange finger sponge
to feed from the plankton-rich sediment, which chokes the fine sponge animals,
preventing them from feeding on phyto plankton. The yellow nipple sponge
has been cleaned already.
f004929: the fan shell (Atrina pectinata zelandica)
provides for 'artificial' rocky habitat in clusters like these, which can
be found on a sandy bottom. Fan shells recruiting in the shelter of a larger
one, are more likely to survive extraction by large storms, and thus a
cluster forms over many years, consisting of many year classes. Notice
the scallops growing in the shelter (behind) of this cluster.
f005108: deadmans finger (Alcyonium sp), solitary
seasquirts and nesting mussels (Modiolarca impacta) have attached
themselves to this fan shell. They are not able to live in or on the surrounding
sand. Invisible to the eye, and burrowed under the sand, various sea soil
organisms enjoy the stability offered by this deep-burrowing shell.
f005121: a large stand of old fan shells has completely changed
the muddy habitat of this harbour entrance (Mahurangi), encouraging a community
of fragile organisms like soft corals and sea slugs to survive. In the
meantime, a large scallop dredge has almost entirely destroyed this habitat.
f005136: a beautifully shaped seaslug (Tritonia incerta)
lives from the soft coral that lives on the substrate provided by the fan
shell bed. The red fingers in the foreground belong to a species of soft
coral (Alcyonarium sp), which has contracted itself into a thick
leathery skin. The thinner orange softcoral in the background is a different
f027104: A South Island shallow water kelp community showing
tall Macrocystis pyrifera amongst a variety of other species.
f026720: a budding bull kelp starts with a strong holdfast,
and a thick stipe. Later, it will be crowned with enormous fronds.
f026704: a shallow water kelp, growing on a level below the
f210336: the strategy of floating one's leaves on the water,
guarantees a sufficient supply of sunlight, but it also subjects all leaves
to extreme forces. Near Christchurch.
f027118: both space on the hard rock and the sunlight coming
from above, are precious. Here a kelp is seen shading out others below
f026728: floating bull kelp leaves provide a spectacular
show of graceful movement.
f027119: an exposed shallow water community of seaweeds,
f027102: a sheltered shallow water community of seaweeds,
f026719: A budding bull kelp is starting to tower above other
exposed water kelps.
f026723: a budding bull kelp plant.
f026435: a snorkeldiver is dwarfed by the enormous fronds
of some bull kelp species. Near Christchurch.
f210714: mature bull kelp fringing a seal rookery, near Bluff.
In the distance, the sheltered bay has been occupied by females with young,
protected by a 'beach master' bull seal. The juvenile seals, however, have
to make do with less desirable spots like the one in the foreground.
f027127: seal and shallow water kelp community. [A6]
f027120: framed by various kelps, a seal gracefully arches
its back in the background.
f026718: sea tulips are seasquirts on stalks. It gives them
the advantage to reach out over other organisms for the nutricious phytoplankton,
distributed by the water's movement.