Kayak and stand-up paddling between Mangroves are popular tourist attractions here in Guadeloupe. The plants are intriguing with their huge root system half lying in the water. But what are Mangroves and how can they survive such a harsh environment as salty water? I´ve been looking for answers in the library of our university when I found the book “Mangrove une forêt dans la mer” 1 (Mangroves a forest in the ocean), where I´ve drawn the information for this post from. So today we are discovering mangroves: The Forest in the Ocean.
Definition and living conditions of Mangroves
Mangroves are tropical forests, partly situated in the ocean. The ecosystem Mangroves consists of the same named plant species. They are colonizing the coastlines between latitudes 30 north and 30 south, with their roots anchored in the ground under the water. Mangroves prefer saltwater diluted by a lot of rain. Therefore, the conditions in the tropics are favourable for them to thrive.
How do mangroves reproduce?
I found it quite astonishing that they reproduce in a sort of viviparity as mammals. The new plant develops as a whole in the mother plant and is transported over the ocean. The survival time of the baby plant depends on the species but can take up to several months and vast distances without setting roots in the sea ground.
Why are mangroves salt tolerant?
It sounds surprising, but Mangroves do not explicitly need salt water for their metabolism. They just found their way to tolerate it. How they handle the huge amount of salt in the ocean differs from species to species. Rhizophora for instance desalinates the whole water, excluding it completely from the osmotic regulation. In consequence, the salt water doesn´t impact the metabolism of Rhizophora. Other species (for example Avicennia Aegiceras) take up the salt and excrete it over their leaves.
Which species do you find in Mangroves?
Mangroves provide a home to many crabs, fish, and molluscs which find shelter and nourishment there. The authors claim that the fauna is “tiny and innumerable” indicating that you can find a lot of small species there as insects or nematodes. For those who had never heard the term Nematodes: They are worm-like animals, but not closely related to the well-known earthworms. The insects provide nourishment to birds, populating mangroves in great numbers. The authors declare that more than 450 vertebrates (mammals, reptiles, and amphibians) profit from the mangroves at least temporarily.
Conclusion
What have we learned while discovering mangroves: The Forest in the Ocean? Mangroves are found in the tropics in littoral regions. Mangroves can tolerate salt water, either by excluding it from their metabolism or by the excretion of salt. They are rich in fish, crabs, and molluscs but are also home to birds and other vertebrates.
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