What type of biome is characterized by the presence of both freshwater and saltwater environments?

The correct answer is the estuary, which is a unique biome where freshwater from rivers and streams meets and mixes with saltwater from the ocean. This mixing of different water types creates a highly productive environment that supports a diverse array of plant and animal life. Estuaries are often rich in nutrients due to the runoff from surrounding land, making them crucial habitats for many species, including fish, birds, and crustaceans.

The transitional nature of estuaries allows them to serve as important breeding and feeding grounds for many aquatic and terrestrial organisms. They also provide crucial ecological services, such as water filtration, flood control, and carbon sequestration.

Other options, while they may share some characteristics, do not fit the description as precisely as estuaries. Wetlands can include both fresh and saltwater, but they typically refer to land areas that are saturated with water, whether it’s fresh or salt, and do not have the mixing dynamics of estuaries. Riverine biomes specifically refer to freshwater environments along rivers and may not involve any saltwater. The littoral zone refers to the area along the shoreline of a body of water, which can include both freshwater and saltwater, but it does not capture the dynamic mixing of these environments