Wetlands are special ecosystems where water and land meet, making “wet land.” The scientific definition is that water covers the soil or is present at or near the surface of the land for the majority of the year. There are many different kinds of wetlands, and wetlands can be found on all the continents except Antarctica. While wetlands share the basic definition around the globe, the specific ecology of wetlands varies in different parts of he world, and even in wetlands that are relatively close to each other.
There are two major types of wetlands: coastal and inland. These are also sometimes called tidal and non-tidal. Inland wetlands are created from freshwater, and are often seasonal. Swamps, bogs, and fens are examples of the variety of types of inland wetlands, and these, like coastal wetlands, can be found across the country and around the world. Estuaries are a special sub-category of coastal wetlands, where fresh water and salt water mix in the wetland, making a habitat of varying salinity.
Estuaries and coastal wetlands are particularly important for the success of ocean fish, because many of these fish lay their eggs in the coastal wetlands. When wetlands are threatened, many fish that spend the majority of their adult life at sea can also be threatened because they have nowhere to lay eggs, and nowhere for the juvenille fish to safely reach adulthood. This makes wetland protection important to the success of the worldwide fishing and shrimping industries.
In North America, there are wetlands from coast to coast in states like California and North Carolina, and from north to south including Alaska and Texas. The temperate zone wetlands are essential to bird migrations, providing resting stops for the long trek between the tropics and the tundra. At these rest stops, the birds can find shelter in the plants growing in the wetlands, and can find plenty of food in the sea animals that live in the water and earth.
A special kind of wetland found in the tropics around the world is the mangrove, which provides shelter to many kinds of tropical marine life. The roots of the mangrove trees grow in and out of the water, making a forest of roots where the marine animals can hide. The leaves and stems from the mangrove trees fall into the water, becoming detritus for small marine creatures to eat, forming the base of the food web.
Detritus is common to all water ecosystems, and all the plants in the wetlands provide material for the so-called “bottom feeders” that consume mostly this decaying plant matter, and which are also lowest on the food chain. The insects, small fish, shellfish, and especially juvenile fish that feed on detritus from the wetland plants become the food for the animals higher up in the food chain, like larger fish, amphibians, reptiles, birds, and in some locations even mammals.
Wetlands are also particularly productive ecosystems. This means that energy and nutrients turn over faster in wetlands than in other ecosystems. Rainforests and coral reefs are other productive systems. Productive ecosystems help sequester carbon by providing fast-growing plants to hold carbon in their matter. These ecosystems can often successfully process toxins because of the fast growth rate, naturally cleaning the water and land. In coastal estuaries this is particularly important because the fresh water has collected pollutants on its journey to the sea.
In addition to cleaning our water, wetlands also provide other important benefits to humans. Wetlands offer flood protection in all regions. The wetlands are like natural sponges that can absorb immense amounts of water in a short amount of time. In coastal zones wetlands provide hurricane protection by creating a buffer zone between the water and the land.