368 Natural Resources Systems Copyright Goodheart-Willcox Co., Inc. Mangrove Swamps Mangrove swamps are tropical tidal wet- lands in which a variety of halophyte trees and shrubs thrive, Figure 15-12. A halophyte is a plant that has adapted to areas with low oxy- gen and high concentrations of salt in the water and/or soil. The term mangrove refers to the type of halophyte trees and shrubs that grow in these swamps. Mangroves are unique plants that extract freshwater from seawater, secrete salt through leaves or in older bark, hoard fresh- water in thick, waxy leaves, and have roots that function in the same manner as a snorkel. There are about 80 identifi ed species of mangroves. The soil in mangroves is similar to that of salt marshes but it typically has a higher level of silt and sediment. The complex root systems pre- vent inland silt and sediment from being washed out to sea and prevent silt and sediment from the ocean from reaching inland freshwater. The mangroves also protect land from wind erosion and function as buffers to the ocean waves. Mangrove swamps are also important to the ecology because they pro- vide habitats for many aquatic and terrestrial animal species, including fi sh, mollusks, birds, monkeys, fl ying foxes, and even tigers. Unfortunately, many of these animals are losing or have lost habitats due to the destruction of man- grove swamps. Mangrove swamps were once seen as useless areas and many were destroyed to make room for coastal development for beachfront homes, hotels, and new beaches. Increased shrimp farming activities also pose a threat to many mangrove swamps. Freshwater Wetlands Freshwater wetlands are those found inland along lakes and ponds, on the fl oodplains of riv- ers and streams, and in isolated, low-lying areas surrounded by dry land, Figure 15-13. Freshwa- ter wetlands are not connected to oceans and do not rely on water from the ocean’s tides as a water supply. Wetlands that are not affected by ocean tides are referred to as nontidal wetlands. The water for most freshwater wetlands comes from precipitation or from streams, lakes, riv- ers, and springs. High groundwater tables also contribute to freshwater wetlands. Nontidal wet- lands are seasonal and experience dry periods that often coincide with seasonal variations of the water supply. happystock/Shutterstock.com Figure 15-12. Mangrove trees are unique plants found in tropical and subtropical mangrove swamps. Mangroves have adapted to the harsh environments with unique methods for filtering salt from the water and special root systems that acquire oxygen from the atmosphere. DM Larson/Shutterstock.com Figure 15-13. The Chilly Slough Wetland near Mackay, Idaho, is one of the few remaining natural, high desert, spring-fed wetlands in the United States.