The estuary where the boat ride takes place contains five very distinct and interesting ecosystems. One of these involves the mangrove trees that grow all along the water. These trees come in
two varieties – the “white” and the “black”. The water here is brackish, which means that it has a fair amount of salt in it. Neither tree can survive in that condition. Yet they do! Here’s how ---
Our attention was drawn first to the larger, white mangrove trees. Each one had one dead branch. The tree has the ability to filter the water. Once filtered, it can live on the fresh water. But, what does it
do with the salt that it filters out? Each tree “chooses” a particular branch in which to store the salt. ONLY that one branch is used for this purpose. However, it cannot survive all the salt, so it eventually dies. Then, another branch is “selected”, and the process continues.
The “black” mangrove is smaller, and has large, dark green leaves. Here and there, however, on each tree, are yellow leaves. This
variety of mangrove has no dead branches, but must also filter the water to survive. So, this tree selects certain leaves in which to store the salt. These leaves turn yellow after a while. Eventually, they fall off and another leaf is used for the salt storage.
Furthermore, around these trees, there appears to be sticks coming up out of the mud everywhere, almost like straws. Hundreds of them. Some of them are
fairly high, but most are under a foot in length. These are actually part of the root system. The mud in which the trees grow is thick and lacks oxygen. So, the trees put roots up out of the ground to help it absorb oxygen and gather other nutrients. At high tide, these roots are covered, but at low tide, they are completely exposed.
