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Recently in Australia, together with Nic from Ultra Coral Australia we had the luck to go and observe Acropora microclados, aka the Strawberry Shortcake (SCC), in its natural environment. And because we’re sure most aquarist don’t realize where Strawberry Shortcake Acro comes from, we decided to share with you what we found out!
The sweet-spot:
First Of All, Strawberry Shortcake Acros are not found everywhere but instead they thrive in a very particular environment. They blossom in high competition, 95% Acropora coral cover habitat which are very small and difficult to find because it’s only a couple 100 meters of very particular reefs that are like that, not all the Great Barrier Reef.
In this particular sweet spot for SSCs competition for real estate is at its peak – this is the best spot on the whole reef, the best 200m out of hundreds of km of reef. Coral need to grow fast in this place, as there are no place for slow growing corals which will be quickly outcompeted and overgrown.
A long way Off-Shore!
The region of the reef we are talking of what is called the ‘hard line’, a well named series of mostly submerged reefs, that are offshore a few miles in front of the great barrier reef. So you not only need to cross the Capricorn channel, which is the hardest part of the journey and a really bumpy ride in between the coast and the Great Barrier Reef. But you also need to cross the GBR itself, through protected channels. Then you need another hour of boat to get off shore of the GBR so if you ever want to get there, expect a long rough ride!
Pounding waves!
The few hundreds meters of high density Acropora ‘groves’ is prime real estate where the most colorful SSC live, right where the waves break! And we are talking about cross-pacific oceanic swells so they are as big as it gets – 20 ft waves are a common occurrence in these places, when it’s not directly a cyclone.
So this has 2 direct consequences:
- It can only be reached when the swell and the wind are down, which is not very often. That’s why SSC don’t come with such regularity, It’s a mission to get them.
- They need very high flow and oxygen. The water is as good as it gets. All these tables corals line up on the slope filtering water and bathing in direct sun.
Low Nutrient water quality!
The Strawberry Shortcake habitat is right on the last oceanic, outer offshore reefs. They simmer in the best, clearest, most oxygenated pure water you can actually find on the reef. When the tide are going down, they are only given left overs of nutrients, tiny things that were missed by the billions of mouths lined up in front of them.
And if you look at the rocks in between corals, apart from a bit of Chlorodesmis fastigiatia toxic algae, there are almost no other algae growing, very few sponges, hydroids… there are no food left for anybody else. Even for fish, there are small school of green chromis, and few Anthias, but you can see their number is not too high. There is just not enough food to sustain large school on these planktivorous fishes even though, there are a lot of shelter for them.
And with a lack of fish to pick on them, most of these plating and table Acros were all polyp extended during the day, feeding 24/7.
The Back Eddy:
Nic dropped us on the spot with perfect timing, right at slack tide, in between low and high tide. So clear water was coming in, and we had minimal water flow. We could enjoy this amazing place for 3 hours.
But when the tide goes out, it hit the opposite side of the reef, and creates a backeddy opposite, just below where the swell is breaking. So when the tide is running down, it creates a down current on this sweet spot. The current just goes down the slope, and all these corals are here to filter it, and remove the last scraps of food from it, that’s why the highest coral cover is on this particular spot.
Translation into aquarium husbandry:
What this means for aquarium care of Strawberry Shortcake Acros is that, ideally, it should be maintained in very low nutrient systems, but with a splash of feeding every other day. The flow should be maximal, and down current getting actually through the colony would be the best. In terms of lighting, we found some nicely colored specimen around 15 m (45 ft) of depth, but the water clarity is optimal there. That must be the explanation because otherwise, they tend to prefer the 5-10 m zone, so the light should be as strong as possible.
Not all A. microclados are SSC:
Finally, we wanted to mention, that Acropora microclados, comes in a variety of colors, and not all are SSC. Only the phosphorescent green base with bright red polyps is what the industry regards as the true Strawberry Shortcake. We found many other color variation of this species on the same reef. Here are some few examples below:
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