Mangrove swamps and sea grasses are both vitally important and critical to the formation and survival of coral reef system. Without the Mangroves and sea grasses, the reefs could not form and many of the creatures found around them would disappear from the seas. How is this possible? Lets look at the various systems and see what each does and how they interact.
Mangrove swamps are found around the coasts of most islands and though out tropics everywhere. They are usually associated with rivers or streams and were once being cut down. People thought they blocked the water flow, silting up the area. Then there as there became fewer mangroves, there became fewer reefs and beaches started to shrink. Was there a correlation between the two? How were the mangroves benefiting the coral reefs?
It seems that the mangroves were blocking the flow of the streams and rivers, but that was needed. Too strong a current and the coral eggs were washed into deeper water where they could not grow. Really strong currents, such as after a major storm, would wash away the coral polyps that had already attached. Those swamps also stopped the silt from filtering out into the sea and smothering the coral reefs. The silt wasn’t all that got stopped either. There were pesticides and fertilizers all of which the mangroves could utilize, but would destroy the coral.
Ironically enough, the sea grasses performed a similar function, just a bit further from shore and in the pure saltwater instead of brackish. They also helped maintain oxygen levels and the roots of the grasses stabilized the sand. The grasses and mangroves both provide shelter and nutrients for many of the small creatures that would later, as adults, move out and live on the coral reefs, helping the reefs survive.
The reefs also though protect the mangrove swamps and sea grasses! It blocks wave action during storms as well as breaks the force of the currents that come out on the depths of the sea. The reefs also slowly break down as parts die, and those decaying parts feed the sea grasses and the mangroves.
That is the way an ecosystem work. It is a complex interaction of numerous species and could be compared to a very complicated machine. The engines is important, but with out the gears the engine just sits and makes noise. A flat tire may not completely stop the car, but it certainly slows it down!
Mangrove swamps and sea grasses help the coral reefs, and get helped in return.
