How do mangroves help us?

Information researched from the Australian Marine Environment Protection Association

Did you know that both the habitat and the trees that live in the sea are called mangroves.

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Mangroves live in the area where the tide moves in and out along the coasts, estuaries and rivers. This area is called the intertidal zone. The tides move in and out twice each day. Depending on the position of the moon and sun along with seasons and storms affects the time and height of the tides.

Did you know that Australia has about 20% of the world’s mangrove forests.

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These forests are far more important to us than we realise:

Mangroves are fish nurseries

Big fish eat little fish. When fish eggs hatch the tiny fish are easy prey for larger fish. Many newly hatched fish get protection by living among mangroves. These tiny fish can feed in the warm shallow water. They are small enough to avoid being eaten by birds. Large fish won’t swim in very shallow water because the many fish eating birds will quickly catch them as they are large targets. Mangroves are a very rich source of food. The mud is full of nutrients where microscopic bacteria, algae and small creatures thrive. It is packed with life for tiny fish to feed on.

Did you know that about two thirds of the marine fish eaten by Australian’s spent part of their life in mangroves. Without mangroves there would be fewer fish to catch and eat.

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Mangroves reduces storm damage

Mangroves live in the shallow intertidal zone and are most common around mudflats and protected coasts, estuaries and rivers. All coasts will be affected by storms and cyclones in tropical zones. During storms and cyclones, seawater can rise even higher than the tides and there are powerful waves. The sea can surge and cover low lying land. When powerful waves strike a mangrove, the mangroves absorb the energy from the waves and break them up. A dense forest of mangroves will stop the waves from reaching land.

Did you know that mangroves reduce the surge of seawater during storms and cyclones. In these conditions, coasts with mangroves will have less flooding from the sea.

Mangroves are a carbon sink

A carbon sink is something that stores carbon in the environment. It stops the carbon from becoming carbon dioxide gas and escaping into the atmosphere. Carbon dioxide in the atmosphere is a greenhouse gas leading to higher temperatures. Mangroves usually grow on mudflats and help to build up the mud. Leaves and other dead material trapped in the mud decompose very slowly or not at all.

Did you know that in a mangrove, carbon is stored in the wood and roots of the trees and also the millions of dead leaves in the mud. There is between two and four times more carbon stored in an area of a mangrove forest compared with a rainforest.

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Mangroves clean storm water

Nearly all the pollution in the sea has come from the land. When it rains litter, chemicals, oil, dirt, leaves and soil can be washed into the sea. When the rain is very heavy the sea around the mouths of rivers becomes highly polluted. Even soil washed into the sea can affect coral reefs because these reefs need perfectly clear water. Mangrove can trap litter preventing it from being eaten by turtles and whales. Much of the dirt, soil and oil will be trapped in the mud. By slowing the movement of water out to sea, some of the chemicals such as fertiliser will have a chance to be used by bacteria or broken down before they reach sensitive places such as coral reefs. However ,too much fertiliser affects the health of mangroves.

Did you know mangroves act as a filter, helping prevent human waste entering the oceans.