Today I came across the most curious scene in nature on my hike along the southernmost coastline of Africa. I haven’t seen this sort of thing anywhere else along these shores and I’m still trying to work out what is really happening here. I found a single rock pool right on the shoreline that appears to have healthy green algae growing on the surface of what is actually salty sea water.
You might look at it and think that it’s nothing unusual but this is the only pool where I have seen this green algae so prolific. None of the other pools in the same region have it. And remember that this is salty sea water. Normally I presume that algae grows in fresh water, like a river, not in the sea. So what is causing this anomaly?
The rock pool appears to be in a border zone, right where the land meets the sea, and it’s mostly undisturbed by waves. But sometimes at high tide the sea does indeed crash over the rocky outer perimeter and into the pool, thus replenishing it on occasion. However, mostly it is still and so it makes a calm surface upon which the healthy green algae can grow.
Upon further inspection I got the impression that the simple solution to this puzzle comes from what might be a fresh water source flowing into this same pool. As a result the stagnant water of the sea is also fed by fresh water coming down the steep cliff and flowing imperceptibly into the same pool. That’s the only conclusion I could come up with.
Since the fresh stream is only seasonal or dependent on whether it has rained or not, the stream is mostly hidden among the jagged rocks and boulders, so it’s hardly noticeable. However, based on the plant growth it looks like this fresh water does indeed trickle into this sea pool right at this spot. And that’s why this sea pool is different from all the rest that I pass on my hike along these sunny shores of Africa way down south.
Normally there is no sign of this kind of fresh looking green algae in sea water but here we have a rare curious divergence based on a hidden fresh water source. It reminds me of just how localized each little micro-climate and ecosystem is at each alcove along this stretch of the shoreline. Conditions vary from one bay to the next and from one hillside to the next.
As I hike along these miles of deserted and remote rocky shores, the conditions are subtly different at each turn. Some slopes receive slightly more sun than others, or are sheltered from the elements, thus facilitating a different plant life compared to the next slope or alcove along the cliffs. Thus in each stretch I can find unique and diverse little plant species that weren’t evident just a few hundred yards further down the coastline.
These little micro-climates result in the vast array of differing species in what is known as one of the most rich and diverse plant kingdoms in the world, called “Fynbos” here in South Africa. Apparently this Fynbos floral kingdom has just as many differing species in it as the entire Amazon jungle region, even though it is a much smaller stretch of land mass here and the plant life is much less overt or noticeable, being non tropical.
Generally one would miss all this detail if we were simply admiring the overall sun, sea and rock, but with enough time and also a degree of patience, it is possible to gradually notice subtle variations and diversity that go to make up this stretch of otherwise unassuming and empty rocky shoreline. It really helps to have no time pressure, and to basically be on holiday. Then one can roam around at your leisure and take the time to become still and observant. That’s when nature reveals itself to you in more detail.