Mangrove propagule

Title Info
Common name Mangrove, Red
Scientific name Rhizophora
Source Dan L. Perlman
Ecosystems Wetlands, aquatic
Wetlands and aquatic Mangroves; Marshes, Swamps
Selection and adaptations Extreme environments
Lessons Water Relations; Distribution and Abundance
Date July 15, 2007
Location Masoala Peninsula,Madagascar,Africa
Mangrove propagule, Madagascar
Related materials: Mangroves

Mangrove propagules, Madagascar. Mangrove plants live in only a narrow range of conditions along tropical coastlines, but it turns out that these are actually very harsh conditions in which to live. In order to reproduce effectively, certain types (such as the genus Rhizophora, seen here) allow their seeds to sprout while still attached to the tree, so that they can develop to a relatively mature state before they float off on the tide to find a place in which to sprout. When these Rhizophora propagules (which look like long beans in this image) find a sandy spot, they stick into the substrate and develop rapidly.

Mangrove swamps, also known as mangals, are very difficult habitats in which to live. Existing at the interface between land and ocean, mangrove swamps are alternately flushed by fresh water and salt water, and their water levels, oxygen levels, and salinity levels change throughout the day as tides move in and out. Plants in this habitat must be able to live under a very wide range of physical and chemical conditions, and very few are able to do so. Dealing with the high salt levels of sea water is a particular problem, and each mangrove species has either evolved methods for excluding salt or for expelling salt once it is absorbed. Mangrove forests function as critical nurseries for many marine species, as they trap and drop large amounts of nutrient rich material among their roots, and therefore play an important role in the economic lives of many tropical human communities. Unfortunately, in too many parts of the world, mangroves have been cut for charcoal or have been replaced by artificial shrimp ponds, which earn vast amounts of money for their owners for the very few years that they are productive (before they become fouled and must be shut down).