The intertidal rocky shore 

identifying brown seaweeds of the intertidal rocky shore 

By Dr J Floor Anthoni (2007)
The brown seaweeds are tough and able to live in wave-exposed waters near the surface. They are the most common seaweeds of the intertidal rocky shore, usually found in and below the sublitoral fringe.
  • brown seaweeds: bull kelp, giant kelp, flapjack, bladder weeds, stringy seaweed, 
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brown seaweeds
All the big and strong seaweeds in New Zealand, and perhaps in the world, consist of brown seaweeds. They are able to live close to the surface, in bright light with a high dose of ultraviolet.
The stringy bladderweeds are tough, flexible and streamlined, and they can survive strong to extreme wave action.
bull kelp (Durvillea antarctica)
f210515: the bull kelp (Durvillea antarctica) has a single round stipe sprouting from a large round holdfast. The fronds branch out to whip-like leaves that float on the water. Inside these leaves the plant has a honey-comb structure. In sheltered waters, the leaves are not whip-like but more flat and also floating.
f210223: bull kelp (Durvillea antarctica) in wild water makes whip-like fronds that yield to the water movement while floating on the surface. This is a good strategy to minimise wave stress. These leaves can grow to 10m in length. The hollow leaves have been used by early Maori to store and preserve muttonbird  (a shearwater).
giant kelp Macrocystis pyrifera
f027104: the giant kelp  (Macrocystis pyrifera) in shallow water, beginning to tower over all other seaweeds.
bullkelp is washed up on the beach
f980326: bullkelp is washed up on the beach because it floats. Here it dries up to tough hard masses that decompose only very slowly. Ancient Maori used the bullkelp as a bag for storing food in.
a young branched Durvillea Willana
f026724: below the floating bullkelp Durvillea antarctica grows a young branched Durvillea Willana on a very strongly attached holdfast. From the intertidal, looking down into the sea, one can hardly imagine how massive this seaweed becomes.
a forest of branching bullkelp (Durvillea willana)
f026435: a diver visits a forest of branching bullkelp (Durvillea willana) whose leaves can grow to a colossal size, one metre wide by five metres long and very thick as well. When these flap around, one must be careful not to get hit.
necklace weed (Hormosira banksii)
f051711: the necklace weed (Hormosira banksii) or Neptune's necklace can store much water in its bladders, which protects it against drying out. It prefers calm conditions and is usually found inside harbours and on the fringe of rockpools. In sheltered waters its beads are large; in exposed sites small.
wiry weed (Carpophyllum angustifolium)
f034931: the wiry weed (Carpophyllum angustifolium) has a thin but very strong stem and small leaves. It survives in the wildest of waters, near the surface of highly exposed reefs where no other seaweeds can grow. Its thin stems are so strong that a man has great problems breaking them. Divers sometimes call it Number Eight wire.
broccoli weed (Xiphophora chondrophylla)
f051700: the broccoli weed or cartilageous weed  (Xiphophora chondrophylla) has flat stems that branch in a flat plane but at the extremities it forms a broccoli-like head. The thick stems are strong and store much water, which allows it to grow at the low tide in moderate exposure.
broccoli seaweed (Xiphophora chondrophylla)
f051703: a broccoli weed (Xiphophora chondrophylla)  begins life by spreading itself in a horizontal plane. The broccoli weed feels a bit like cartilage (Greek: chondros).
flapjack Carpophyllum maschalocarpum
f051111: the flapjack (Carpophyllum maschalocarpum) has flat stems that branch in a flat plane with pointed leaves and large pointed float bladders. Its strength rates in between the strong wiry weed and the featherweed. It tolerates short exposure to sun and air and prefers to live in sheltered to moderately exposed conditions.
feather weed (Carpophyllum flexuosum)
f050217: the feather weed (Carpophyllum flexuosum) is not very strong and prefers to live in moderate exposure where it is not prone to drying out. It has a flat stem and finely branched leaves and small float bladders. It is believed that it has several growth forms, but these may well be separate species. found on E side of N Island.
stalked kelp (Ecklonia radiata)
f006828: the stalked kelp (Ecklonia radiata) stands erect by the stiffness of its stalk, rather than by float bladders. Its large crown makes it susceptible to being pulled off the rocks by waves, so it prefers the calm of the deep. Here a sea urchin is considering to clear-fell it, as it is standing inside the urchin barren zone.
flexible weed (Carpophyllum flexuosum)
f048401: the flexible weed (Carpophyllum flexuosum) has an almost straight flat stem and long leaves with a mid-rib and smooth edges. It is not strong and prefers calm conditions. The flexible weed is particularly successful inside harbours, as it is able to shed deposition by sloughing it off.
tall flexible weed Carpophyllum flexuosum
f048306: in sheltered conditions the flexible weed (Carpophyllum flexuosum) can grow over 6 m tall, at times forming veritable forests, but such forests can disappear overnight by a large storm.
sausage weed (Cystophora torulosa)
f042030: the zigzag sausage weed (Cystophora torulosa) has a round stem that zig-zags in between each side branch. Its leaves look like sausages. It has small float bladders.
pillow weed (Colpomenia peregrina)
f032335: the pillow weed (Colpomenia sinuosa) is hollow inside but not able to retain water. It is found in stable rock pools and can grow on other seaweeds.
f042208: a branch of slender zigzag weed (Cystophora retroflexa) , often confused with featherweed.
f051931: slender zigzag weed.
f050308: ?
f042218: brown halo weed (Halopteris sp.) has light coloured tips, resembling a halo. It is small (20cm) and finely branched. there are eight species of Halopteris in NZ.
brown tongue weed (Glossophora kunthii)
f051832: brown tongue weed (Glossophora kunthii) consist of flat straps, repeatedly branching in two (branching dichotomously). Mature fronds have little tongues as 'hair' growing on them.
f051713: Zonaria angustata? a small-leafed brown seaweed which stays small. It has a white margin and makes a zoned appearance.
f042212: Zonaria sp.

0608240: thin threads of the filamentous brown seaweed Bachelotia fulvescens?.
halo weed (Halopteris sp)
f051637: halo weed (Halopteris sp) has a light coloured halo over the tips of its leaves. It can be purple with yellow halos.