#004 Brickyard Full of Dreams

There is a place in the north where few swimmers go, and which is inaccessible in all but the lowest tides. Its name is Brickyard Park and it is perhaps the most splendid place in all of Gong.

 

Beneath the cliff the rock ledge stretches out a hundred metres into bright, deep blue ocean. Baitweed grows on every surface, making an emerald carpet of the ledge. A smattering of rock pools reflect a sky the colour of a robin’s egg. Rather than a shelf over the ocean, the Brickyard reminds one of a meadow in the sunshine after a storm.

When the tide is at its lowest waves slop against the eroding rock at the ledge’s chin. Water rush up white and foamy up a natural gutter, and when it drains back into the ocean, tall hanks of kelp are seen pulling tight against their moorings.

The pools are deep. Young Black Drummers and Common Silversides grow fat in the autumn, waiting for winter when they will migrate to the ocean. Families of leopard-print Smooth Toadfish chase each others’ tails, while Cocos Frillgobies, Jumping Blennies and Eastern Fortescues grow impatient, waiting for the months when the pools will be peaceful once more. Anemones, Eight-Armed Seastars and Elephant Snails cluster on the shallow verges of the pools, while urchins, oysters and Warreners live ever-changing lives on the substrate.

Here and there Sooty Oyster Catchers stroll, tall black birds with blood red legs and beaks, hunting for oysters, limpets and snails. Teenagers tremble in unseasonal bikinis, daring each other to leap into the ocean. With a whoop and a splash one is gone, paddling out into the depthless blue.

To the south is one can see the city, the rolling coastline and the great green bulk of the Escarpment. Late afternoon light spirals like diamonds from the crests of waves. This place is paradise.

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Its moods change in an instant. In the rainy autumn season, the swell reaches eight feet. A fast-rising tide rushes up the gutter and fills the innumerable channels with white foam. With even an inch of water over the shelf, the Brickyard becomes dangerous, sudden deep pits and pools hidden beneath kelp to trip the unwary explorer. The shelf is swiftly cut off from the beach. A rockslip on the shelf’s corner forces wanderers out into deeper water, where an unpredictable current can rip away one’s feet.

There is no comfort even in the cliff at one’s back. Its verges are soft, prone to collapse. Rugged shrubs grasp the edge. Dozens of their number lay drying on the ledge below. Boulders the size of cars strew haphazardly at the cliff’s foot. This is not the place to be in a storm.

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Elephant Snails, Eight-Armed Seastars, urchins and limpets sunbathe in a shallow corner.

And yet the Brickyard is teeming with life. Existence here revolves around the Baitweed. Its satin emerald appearance makes Baitweed a visual pleasure, and it is soft and cushiony underfoot. It looks almost like grass spun from velvet. Baitweed can be eaten by humans, is full of nutrients and tastes good. However, humans are not the most important consumers of Baitweed. Fish, particularly Black Drummers and Ludericks, are so fond of Baitweed that they will even take it off a hook.

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#002 Baitweed (Ulva compressa)

Despite their infamy as some of Australia’s only herbivorous angling fish, in their infancy, Black Drummers are mainly carnivorous. They will eat small snails, Brine Shrimp and any stray bit of meat that happens their way. As they grow older, these fish incorporate more and more algae into their diets, until they become more herbivorous than carnivorous. It’s interesting to note that ichthyologists suggest there be no such thing as a purely herbivorous fish. When we consider land animals, we think very much in terms of “Cows are herbivores, cats are carnivores.” In truth, most animals are omnivorous, only to a greater or lesser extent. Cows and deer will supplement their diets with insects and the odd bit of meat, and “carnivores” such as dogs will happily include as much as 30% plant matter into their diets (not Salty. The closest Salty comes to a vegetable is maple-flavoured bacon.)

So while a Black Drummer starts life picking out the tiny snails and arthropods living amongst the strands of Baitweed, in later life they prefer the green algae itself.

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#115 Black Drummer (Girella elevata)

In the Brickyard, Black Drummers occupy large, deep pools, swimming in bands of three and four, generally governed by a “boss” Drummer. They are deep-bodied, strong fish. Infants are striped silver and dark grey, making them appear very much like silver striped Ludericks. As they grow older, the stripes fade, leaving Black Drummers somewhere between sandy brown, deep blue and black. They can also change colour with mood. In the Dangerpus Labs I keep three Black Drummers, Holly, Molly and Dolly. Holly is the boss and Molly is a boy. I often watch them after being fed, where Holly becomes a stormy dark grey and flashes around the tank with her dorsal spines erect and her gill coverings open. She makes her appear as big and intimidating as possible. Her sister, the docile Dolly, will become a buttery silver, keeping to herself near the bottom of the tank.

Once, when I introduced a new fish into the tank, Holly turned such a jet black that her dark grey stripes (she was quite young at the time) stood out in stark relief. She then swam slowly backwards around the new fish. It was clear to everybody that Holly was not happy.

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Keen tracks Black Drummers. Note the field of Baitweed colouring the rocks green. This entire shelf is usually submerged.

There is one more animal to keep your eye out for in Brickyard Park: the Elephant Snail (Scutus antipodes). While uncommon elsewhere, in the Brickyard Elephant Snails are in abundance.

These huge black gastropods are the largest of the false limpets, growing up to 150 mm in length. They are generally sedentary creatures, though can move quickly when disturbed. You will know one when you see one! In the Brickyard they hang around the verges of pools, in crevices otherwise populated with seastars, urchins and limpets. They are massive black blobs with two distinct antennae and a white shield-shaped shell. If you put your finger gently to the snail’s back, you can pull the black membrane right up over the shell. If you do this, there will undoubtedly be some baffled antennae-swaying on part of the snail, but they are soft and muscular and quite pleasant to stroke. If I had the strength to break their suction-grip on the rocks, I would very much like to let one crawl around my arm.

 

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#028 Elephant Snail (Scutus antipodes) … Good old Scutus. A good bloke, that Scutus.

Elephant Snails are algae feeders, but do they eat Baitweed? I don’t know. That is something I need your help to find out. Also interesting is that Baitweed is known to grow in polluted sites with high levels of nutrients, such as fertiliser runoff. This kind of pollution is always a risk near coastal towns, but the Brickyard is especially notable for its abundance of Baitweed. Is there an especial amount of runoff reaching the water from Coledale township?

Join Salty and I next time for a close encounter of the eight-legged kind as we get close and personal with a Gloomy Octopus, and I go swimming with a Wobbygong shark.

Until then, happy exploring!

 

 

A Windang Shindig

The Gong 151
#003 A Windang Shindig

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On a cool and blustery day in March, Salty, Keen Wasabi and I hiked around Lake Illawarra foreshore to the sandy arm of Windang Island. The island’s green top rises conspicuously from the lip of the lake. Anglers endure relentless plumes of spray on the seaward cliffs, each wave sending waterfalls cascading down deep flutes in the rock. Snorkelers proliferate in the summer, diving from ledges exposed at low tide, while swimmers wander up from Warilla Beach to survey the long and peaceful bay. The island is also notorious for sharks.

At 11 o’ clock the tide was at about 0.6 metres and dropping. Things that are usually submerged were becoming exposed. Keen and I dropped our nets and tanks on a rock ledge and waded out amongst the pools.

Soon we were walking on mats of Neptune’s Necklace (Hormosira banksii). This brown alga is made distinct by the string of olive-coloured beads that make up its thallus (body). Like plants, brown algae uses chlorophyll to photosynthesise and  absorb energy from the sun. Unlike plants, it also produces xanthophyll, a yellow pigment. This gives brown algae its distinct brown-green colour.

While at first it seems weird – after all, chlorophyll works perfectly well for plants – the secret of brown algae is where it exists in the ocean. Red light is bad at penetrating the ocean’s surface. Green light however penetrates deeply into the water. Because a thing’s colour is determined by the light it reflects (meaning green plants reflect green light) algae need to be differently coloured to absorb the light available to them beneath the waves. For Neptune’s Necklace, this means disguising its green chlorophyll with red pigment.

What I find fascinating about Neptune’s Necklace is just how well-equipped it is to maximise its light exposure. The alga is made up of multiple strands of beads called thalli. Each bead is made of a  spongey tissue filled with air and protected by a waxy coating. When submerged, the air makes the beads float, drawing them towards the surface, where there is more light. When the tide drops, the beads lay like a carpet across the rocks, their waxy coating preventing them from losing too much moisture.

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Shells embedded in the island’s dirt wall.

Neptune isn’t the only one who fancies his algae. As we sat by twin rock pools on the low intertidal, Keen and I counted 135 Zebra Top Snails (Austrocochlea porcata) in and around the strings of beads. Interestingly, of all the species of snail in the pools, only Zebra Tops were found on the Neptune’s Necklace. Smaller snails seemed to prefer the shelter of the algae more than the larger ones, who preferred grazing on an encrusting brown algae on the bottom of the pools.

Up until last week, I kept five Zebra Tops Snails in my laboratory aquarium. They eat the slimy brown algae that is a fact of aquarium life, and it’s fun watching a snail licking glass.

Woe betide me, this week I am down to three Zebra Tops. The reason? Clever fish. Working together, two of my fish (Holly, a Black Drummer, and Dart, a Blackspot Sergeant) repeatedly ram the Zebra Tops until they come unstuck from the glass and tumble upside-down into the sand.

Like other marine snails, Zebra Tops have a tough disc called an operculum that they can draw over the opening in their shell, like shutting a door. My fish are quite unable to get past the operculum. But, as they learned, if the snail wants to right itself, it has to push its operculum aside and stretch its soft body around the top of the shell to grab a hold of something solid. When that is done, the snail gives a quick pull and flips around upright.

Holly and Dart wait until the snail’s soft body is exposed, and attack. In just a few strikes the fish have conquered a snail as big as themselves. This bringing down of the mammoth results in tank-wide excitement, as the other drummers rush in for a nibble and the crab dances out of his cave, claws waving.

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Scary-story-snail face.

On the beach, Zebra Tops have more insidious enemies than tiny fish. Seastars prowl for young snails. You will have seen seastars sold as trinkets and jewellery. Dried and bleached, they offer poor comparison to these active hunters.

A sea star’s underside is covered in hundreds of tube feet. At the end of each arm, there is a splay of probing fingers and a rudimentary eye. A seastar can move as swiftly as a snail or abalone. It crawls over its pray, wrapping it in powerful arms. It then everts its stomach, coating its prey in digestive juices. Finally the seastar draws its stomach and its melted pray back into its body.

One such predator on Windang Island is the Eight-Armed Seastar (Meridiastra calcar.) It’s obvious when these seastars are busy eating, as their central disc will be raised into a hump, the prey engulfed beneath it. While snails are high on the menu, Eight-Armed Seastars will also graze on algae, and I have even seen them feasting on crabs’ legs and fishes’ tails.

Perhaps one reason Zebra Tops choose to hide amongst the beads of Neptune’s Necklace is that it is not readily navigated by seastars. Seastars probably also have poor vision, and cannot tell a small Zebra Top from a bead.

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Anglers enticing sharks with their juicy backsides.

“The sale of souls to gain the whole world is completely voluntary and almost unanimous…but not quite.”

As we finished counting Zebra Tops (Keen felt sorry for some and rescued them from seastars. But echinoderms need to eat too!) we noticed a huge white and grey Pelican riding thermals rising from the hot exposed rock. Wind gusted hard over the island’s top, and the Pelican would surf thermals for a minute before lowering itself into the gusts and riding in a wide crescent out over the ocean. Seeming without a care in the world, it would then coast over the island and catch another thermal.

“Do you think it’s having fun?” said Keen.

“Looks like it,” I said.

We watched the seabird, a proud example of Australian Pelican (Pelecanus conspicillatus.) Its wings wobbled as it hovered on the thermal. Then – it dropped and swooped out over the waves. In moments it was back.

“It’s not looking for food,” I said, as the seabird hung suspended in the air. “And that does look like fun.”

Keen sighed. “I wish I had wings.”

We spent a while chasing gobies in rock pools, and then we were hungry, which meant it was time to go. On the return hike to the car we walked past the mouth of Lake Illawarra. The tide was starting to rise and the foreshore was wet and dark. It also appeared to be moving.

“Hey, crabs!” I had ditched my gear and was dancing amongst crabs in a second. “Look, Keen, soldier crabs!”

All across the foreshore, an army of perhaps ten thousand soldier crabs were digging out new holes above the waterline. In amongst the waves of smaller Mictyris platycheles were large Light-Blue Soldier Crabs (Mictyris longicarpus) looking like horses amongst foot soldiers. They were oblivious to us. By the drove they kept on digging, while others processed sand through their mouthparts, restlessly surging across the boundary of surf and sand.

Salty poked his nose into a crab’s back, and watched baffled as the crab burrowed in a spiral into the wet sand. In seconds it was up again, scuttling for higher ground. From the water a Pelican watched on idly, sailing as majestically as a brilliant white yacht. Storm clouds bathed the escarpment beyond.

Keen and I finished the journey to the car in high spirits. The world can be savage, it’s true. But from the snails sampling the finest delicacies of the sea, to the pelican surveying its kingdom, it is also a world of great joy and satisfaction.

Thank you Keen and Salty for a banger of a trip out of Windang Island. Thanks to you two, I’m finally able to present the first five Gong 151 species!

 

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#001 Neptune’s Necklace (Hormosira banksii)

Length: Up to 300 mm

Zone: Low intertidal

Sighted: Day, on rocky substrate in pools and low-lying channels

Locations: Windang Island, common

 

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#027 Zebra Top Snail (Austrocochlea porcata)

Height: Up to 25mm

Zone: Low intertidal

Sighted: Day, on rocky substrate and algae fronds

Locations: Windang Island, common

 

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#078 Light-Blue Soldier Crab (Mictyris longicarpus)

Carapace width: Up to 25mm

Zone: Low intertidal (brackish water)

Sighted: Day, on border of sand and sea

Location: Windang Island (Lake Illawarra entrance), common

 

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#090 Eight-Armed Seastar (Meridiastra calcar)

Arm radius: Up to 50 mm

Zone: Low intertidal

Sighted: Day, on submerged rocks and rocky substrate

Locations: Windang Island, uncommon

 

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# 138 Australian Pelican (Pelecanus conspicillatus)

Wingspan: Up to 2.6 m

Zone: Shore

Sighted: Day, cruising on calm water or riding on thermals.

Locations: Windang Island, uncommon

 

Now it’s up to you. Get out into the Gong and meet some animals!

For the five species listed, we need to find:

  • Which locations they can be found
  • Their numbers in each location
  • Their interactions with other species
  • What they eat
  • What they do all day

You can join Salty and I for a day of discovering sea creatures on Saturday 8th April 2017 at Bellambi Beach. Some snacks will be provided. Bring a bottle of water, your camera, and let’s see what we find.

*Coming soon: Updated link to the 151 Field Guide*