|
|
|
Mangroves
These trees and shrubs are adapted to a saltwater environment. More than fifty species can be found along fringing coastal habitats in tropical regions around the globe. Their presence is limited at Northern and Southern latitudes by frost lines. In general land masses from islands to estuaries influence the establishment of mangrove "forests."
Mangroves are often prolific, growing in large clusters or masses. The common Florida coastal species known as the Red Mangrove Tree (Rhizophora mangle) has an elaborate root system. It develops anchor or prop roots that can be observed above the water line in mature trees. This species with its characteristic mangrove look is quite popular in the marine aquarium trade where it is grown from aquacultured seedlings into full fledged trees in home aquariums
Growth and Development
Florida's Red Mangrove tree reproduces by the production of seedlings or propagules. These torpedo shaped sprouts are dropped by the parent tree into the water. The propagules can settle out immediately or float for up to twelve months until finding suitable ground to settle into.
Once settled, the seedlings take root in anaerobic substrates with the roots growing horizontally. Aerial prop roots develop later as the trees mature. The prop roots assist with taking in oxygen and provide an anchorage for stability. In Florida the Red Mangroves grow into small trees, averaging about 20 feet high. They have groups of 3 to 4 light yellow flowers that appear in late spring. The leaves are oval or egg-shaped, tough and shiny dark green on top. The bottom side is a lighter green.
In some areas of southern Florida where mangroves encounter shoreline homes and buildings the trees can be quite intrusive. And given that they are a protected species it requires a lot of time and effort with various government agencies before a single branch can be pruned!
Tidal Creeks
One interesting feature of the eastern region of the Florida Keys close to the mainland tip of Florida is the presence of tidal creeks. These are channels of water that originate in shallow bays and wind through the salt marshes surrounding land masses. The direction and speed of the water flow changes with the rise and fall of the tide. During high tide, tidal creeks flush the salt marsh communities with water and food. Low tide movements, in turn, export food and nutrients back into the surrounding bays. Mangroves with their elaborate network of root masses help to regulate the amount of nutrients that wash back out to bays and on to the coral reefs.
Mangroves in Captivity
Having outgrown it's previous aquarium this Red Mangrove was ready for a new tank. When the anaerobic substrate was removed it revealed the typical horizontal growth form of the roots. The network of larger "cable roots" produced thick mats of very fine and delicate secondary roots. The entire submerged root network was six feet long by four feet wide!
Regular misting of fresh water over the leaves weekly produced notable growth perks in this specimen. Also, regular pruning became necessary as the tree began to grow too closely to the light fixture. The addition of magnesium and testing of magnesium levels has been suggested as helpful in maintaining the Red Mangrove tree.
A biological filter with mangroves on a stingray exhibit at Living Sea Aquarium, Chicago, Illinois.
Further ReadingCalumpong, H. and Menez, E. 1997. Field Guide to the Common Mangroves, Seagrasses and Algae of the Philippines. Bookmark, Inc. Makati City, Philippines. 197 pp. Sprung, J. 1999. A Guide to the Ecology and Care of the Mangroves. Two Little Fishies, Inc. Coconut Grove, Florida, USA. 12 pp. Tomascik, T., Mah, A., Nontji, A., and Moosa, M. 1997. The Ecology of Indonesian Seas, Volume VIII Part Two. Periplus Editions (HK) Ltd. 745 pp.
|
|
Copyright © 2008 AquaTouch
|
Since
mangroves grow close to coastal environments they are often found in a variety
of terrestrial soils, clays, marine sediments, and sands. Freshwater runoff
helps to regulate their salinity balance and different species of mangroves have
different salt level tolerances. The dropping of leaves and associated leaf
"litter" account for a substantial portion of the nutrient resources
found in coastal areas. The leaves are feed on by bacteria and fungi,
decomposing them into the nutritious detritus that then flows out into the
marine food web. Mangroves are also very important in contributing to the
biodiversity of near shore environments and associated coral reefs. The roots of
the trees are a nursery for juvenile fishes as well as a host of crustaceans and
other invertebrates. When mangrove forests are removed or destroyed they have a
direct effect on the health of adjacent marine habitats. These well documented
impacts are also seen in the biodiversity of other habitats where the number and
variety of animals like fishes are reduced. 
One
of the most challenging parts of this attempt at transplanting the mature Red
Mangrove tree was reintroducing it into a new aquarium without damaging the
finer root masses. Even with extreme care some damage could not be prevented.
But more importantly the problem was the exposure of the root system to the air
and an oxygenated water environment. Also the new substrate was thoroughly
oxygenated. Once transplanted the nutrient uptake process of the finer roots and
their ability to regulate gasses was impeded. In the end this transplant was
unsuccessful. The prop branches and main trunk are all that remain.
