Chapter 15 Wetlands 361 Copyright Goodheart-Willcox Co., Inc. Food Source Wetlands are key contributors of human food sources, such as fi sh, clams, oysters, shrimp, shellfi sh, rice, seaweed, blueberries, cranberries, and water fowl. According to the Ramsar Convention, an estimated one billion people rely on fi sh as their main or sole source of animal protein. Wetlands also have intricate food webs that support a wide variety of wildlife, including mam- mals, reptiles, amphibians, insects, and other anthropods. Wetland Soils Wetland soils are referred to as hydric soils. Hydric soils are soils that are saturated for long enough periods to develop anaerobic conditions. The term anaerobic indicates the absence of oxygen. The type of soil found in a wetland is determined by many factors, including the climate, water, surrounding soil com- position, and water source. Almost all soils have traces of minerals and organic materials in some horizons, but most soils are dominantly mineral or organic. Mineral Wetland Soils As discussed in Chapter 8, What Is Soil?, soil is formed through weathering of rocks which releases the primary minerals contained within the rock. Addi- tional weathering changes the primary minerals into the secondary minerals that make up part of the small particles within the soil. Due in part to the anaero- bic conditions of the constantly saturated soil, many of the minerals are trans- formed into forms that are not usable to many plants. Additional minerals may accumulate when the area is saturated and water is fl owing from other areas. The types of minerals found in a wetland depend on many factors, including the specifi c types of rock found in the area. The color and texture of sand on a beach, for example, is determined by the types of minerals it contains, Figure 15-5. How do temperature changes of each season change the way microorganisms in the soil react to pollutants? Thinking Critically Jaktana phongphuek/Shutterstock.com Figure 15-5. Sand’s color is determined by the types of rock from which the sand was formed. Black sand is eroded basalt (A), white sand is calcium carbonate (B), and green sand is basalt with high amounts of a green mineral called olivine (C). If you look closely at brown or golden sand (D), you will see it is usually made of many different colored grains. Each colored grain is from a different type of rock. Bravo de Luz/Shutterstock.com A D Simon Dannhauer/Shutterstock.com B Galina Barskaya/Shutterstock.com C