What type of ecosystems are found in both fresh and salt water?

Aquatic ecosystems are defined by water as their primary environmental medium and encompass both freshwater and saltwater environments. This includes diverse habitats such as rivers, lakes, ponds (which are freshwater ecosystems), as well as oceans, estuaries, and coastal areas (which are saltwater ecosystems). The presence of these two types of water bodies under the overarching category of aquatic ecosystems highlights their fundamental role in supporting a variety of biological communities that exhibit adaptations to their specific aquatic environments.

Terrestrial ecosystems, on the other hand, are characterized by land environments, while marine ecosystems specifically refer to saltwater areas, excluding freshwater ecosystems. Urban ecosystems are human-made environments and don't fit the natural classification of ecosystems based solely on water types. Thus, the broader classification of aquatic ecosystems correctly encompasses both freshwater and saltwater systems.