Final answer:
Estuaries are environments where freshwater meets seawater, creating a nutrient-rich habitat due to the influx from both tides and land runoff. The statement about estuaries receiving nutrients from both sources is true.
Step-by-step explanation:
The statement that estuaries receive nutrients both from tides and from streams and rivers is true. Estuaries are biologically diverse environments where freshwater from rivers and streams mixes with salty seawater. This mixture creates a brackish water ecosystem. The salinity levels vary due to the flow of freshwater, as well as the ebb and flow of tides. Estuaries are considered some of the most productive ecosystems because they receive nutrients from both the land and the sea, supporting a diverse range of species, including young offspring of crustaceans, mollusks, and fish. Furthermore, runoff from land brings additional nutrients to estuaries, which, along with sunlight exposure and other factors, influences the populations of phytoplankton, mussels, and other organisms.