Saturday, December 1, 2007


Interdependence


The Daintree Coast in Far North Queensland is a very popular tourist destination which is marketed to the world by virtue of its diverse natural landscape.

The world famous Great Barrier Reef lies just off shore. Adjacent it, on the coast, the Daintree Rainforest is widely considered to be the most ancient rainforest on Earth. Between the rainforest and the reef, growing along the rivers and estuaries in the region, resides the most diverse mangrove on the planet, with more than two thirds of the total diversity of mangrove trees known to man.

What the casual visitor is seldom made aware of is that these three systems are intimately and inseparably interconnected.

Interference with one system affects the others in ways that we are only now starting to appreciate.

There are numerous lookouts along the coast which reveal all three systems in spectacular panoramic detail. It’s worth briefly describing this amazing relationship as it is an excellent example of the interconnectedness that we are beginning to realize is an important feature of our living planet.

The Great Barrier Reef requires certain nutrients that originate on the land. They start out in the costal forests in the form of leaves and sticks and things that get flushed out of the forests when it rains. But if lots of leaves and sticks made it all the way out to the reef, the reef would end up covered by lots leaves and sticks.

This would be a problem.

Apart from the obvious impact of being buried by the debris, the tons of detritus decomposing in the ocean would release rich organic chemistry over the reef. This would have a direct, chemical impact on the reef and could also fuel algal blooms which would seriously reduce the amount of light getting to the coral. So the reef does not need direct rainforest run-off. It needs filtered rainforest nutrients.

This is where the mangroves come in.

The mangroves are the filter. The dense, semi-submerged bank-side vegetation acts as a very efficient filter trapping the floating detritus and keeping it there as it breaks down in the rivers and estuaries. By the time the water leaves the river and heads out to sea, it contains exactly the right balance of nutrients for the reef to use.

It goes further than that though. Do you like sea food?

A great deal of what we call sea food and a lot of what we don’t call sea food begins life in the well protected and nutrient rich environment of the mangroves. They are the perfect nursery. In fact the fishing industry refers to mangroves as nurseries.

Many of the creatures from the reef, and from either side of the reef, start their lives in the coastal mangrove forests. Upon maturity, these young sea creatures migrate out to the reef, bringing with them the rainforest nutrients that they had been assimilating during the mangrove phase of their lives.

In this sense, the mangroves are a factory; tasked with the conversion of rainforest detritus into self-guided, reef-bound nutrient packages called sea-life.

Of course, it goes a lot further than that.

As much as the reef relies on these coastal systems, without the reef there would probably be no mangroves or rainforest on the Daintree coast.

The Pacific Ocean is a very poorly named body of water. Pacific means calm, peaceful. Yet calm and peaceful, that ocean is not.

Mangroves simply can’t establish in crashing surf and rainforest needs to keep very tight control over its internal climatic conditions which would be impossible in the face of constant oceanic weather conditions.

The reef forms a physical barrier against the Pacific swell, which makes this coast very bad for surfing but perfect for mangroves.

As for the weather, although the reef is under water, it still has an enormous effect on the atmosphere above it. Between the reef and the coast there is a large body of water that is trapped by the reef over a shallow sandy seabed. This shallow sandy sea sits there in the tropical sun, warms up and evaporates, creating a huge wall of hot, wet air that sits just off the coast and acts as a barrier or a buffer against the weather coming in from the Pacific. This ‘weather-wall’ protects the coast but as it does so it is blown into the coast by the very weather it is protecting us from. As this warm wet air gets forced over the mountains it experiences a pressure change and a temperature change which condenses the water and squeezes it out of the air and onto the rainforest; and if you don’t get rain, you don’t get rainforest. Nor do you get rainforest nutrients being flushed out of the forests, through the mangroves and out to the reef and so on…

In reality, what we have here is not three different systems at all. Rather, what we have is three parts of one system. They are no more separate from each other than your leg is from your liver. If fact, this is just a one example of what we now know to be a fundamental feature of the natural world. It applies to every living system regardless of size, from the microscopic to the global.


It seems that there is not a living system on this planet that exists independently of all others.

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