Baldock, R. N. (2015). Marine indicator species of reefs: III. Calcareous reefs of dune rock (aeolianite) in rough, cold-temperate waters. Algae Revealed. 4pp.

Adelaide: State Herbarium of South Australia. flora.sa.gov.au/algae_revealed

MARINE INDICATOR SPECIES OF REEFS:

III. CALCAREOUS REEFS OF DUNE-ROCK (AEOLIANITE) IN ROUGH,

COLD-TEMPERATE WATERS Examples: Cape Dombey, Robe and Beachport South Australia

Steep cliffs, pot-holed, flat rock platforms, isolated sea-stacks and arches at Cape Dombey

vertical cliff-face grazed bare by

molluscs and dense algal mats

exposed at low tide

pot-holed reef shelf wave-pounded reef edge with

Bull Kelp

fronds of Giant Kelp floating at

the surface from attachments deep below and distant rock arches

eroded

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Baldock, R. N. (2015). Marine indicator species of reefs: III. Calcareous reefs of dune rock (aeolianite) in rough, cold-temperate waters. Algae Revealed. 4pp.

Adelaide: State Herbarium of South Australia. flora.sa.gov.au/algae_revealed

THUMBNAIL SKETCHES OF INDICATOR ORGANISMS ― DISTRIBUTED ON THE REEF ACCORDING

TO TIDE LEVELS

1a. the marine lichen, Caloplaca, in the “splash” zone above high tide dries and becomes bright

orange during summer. Tiny blue snails create a

distinct browse-line lower in the splash zone

1b, 2. blue snails, Austrolittorina, to 16 mm tall,

grazing black marine lichen, Lichina, in the

region above high tide, kept moist by occasional wave splash

3a.

3a. six-plated barnacle, Chthamalus antennatus,

about 12mm across may grow high up in the

intertidal region

3b. honeycomb barnacles, Chamaesipho tasmanica, about 6 mm across, seen here with a few blue

snails, squash together in groups in the upper

intertidal, and can be difficult to see against the eroded background rocks.

3c. surf barnacle Catomerus polymerus, 30 mm

across, seen here with a few black mussels.

grows in the mid-intertidal on rough coasts

4a-b. a variety of molluscs graze the mid-intertidal

clean of algae. Because they do not venture down

into the lower intertidal due to predation, sea-lettuce and other algae can grow there prolifically

4a. pied limpet, Patelloida latistrigata to 25 mm

wide is often common but unnoticed, It occupies

small rock depressions. The top of the shell is

usually heavily eroded

4b. the orange-edged limpet, Cellana solida, found

on rough coasts, may be 60 mm across

5, 6. brown, wrinkled Neptune’s fingers, Splachnidium, amongst lozenges of blue-green

algae Calothrix australis (formerly C. firma)

7. the red alga laver, Porphyra, may grow in the

mid-intertidal during winter

8. white worm tubes, Galeolaria caespitosa, may

form a prominent band on more vertical rocks in

the mid-intertidal

9. sea lettuce, Ulva, seen here with stunted Hormosira surrounding a rock pool in the lower

intertidal can be prolific in spring

Baldock, R. N. (2015). Marine indicator species of reefs: III. Dune rock (aeolianite) reefs in rough cold-temperate waters. Algae Revealed.4pp. Adelaide: State

Herbarium of South Australia. flora.sa.gov.au/algae_revealed

10. rock pools, full of a mix of flat or tufted brown algae and red algae

11. the algal mats in the lower intertidal can be dense

and species rich. Shown above: the red alga

Griffithsia teges with yellow tips to filaments, and three species of the green alga Caulerpa

12. Neptune’s necklace, Hormosira banksii, about 300 mm tall, in the lower intertidal, forms chains

of brown beads

13. cunjevoi, Pyura stolonifera, is a seasquirt

attached to rocks in the lower intertidal, often with a fuzzy coating of red algae

14. the large chiton, Plaxiphora albida, previously Poneroplax, to 100 mm long, with broad girdle

coated with a fuzz of algae, grazes the lower

intertidal

15. in the region of wave surge at the reef edge, bull kelp, Durvillea, stands on a trunk-like stalk to

400 mm tall, its large, broad rubbery blade

shredded at the edges into belt-like strands

16. algal mats extend under the reef edge.

They contain many red species, but the largest

algae are brown, such as crayweed, Phyllospora, shown above

16. beds of bright green Caulerpa contrast with the dominant brown algae of shallow waters

17. giant kelp, Macrocystis, from shallow water to

20 m deep, attaches to rocks with a branching,

root-like holdfast giving rise to elastic strands ending in wrinkled, narrow blades held at the

water surface by gas bladders

17. detail of Macrocystis blades and gas bladders

17. leafy fronds of Macrocystis may rise from 20m

deep

Baldock, R. N. (2015). Marine indicator species of reefs: III. Dune rock (aeolianite) reefs in rough cold-temperate waters. Algae Revealed.4pp. Adelaide: State

Herbarium of South Australia. flora.sa.gov.au/algae_revealed