AP BIOLOGY

Detailed explanation-1: -In a typical estuary, there is a constant change in the salinity of the water. As the tide rises, water from the ocean begins to surge into the mouth of a river, bringing with it higher levels of salt. This results in an increase in the salinity of the water in an estuary.

Detailed explanation-2: -Estuaries-areas where fresh and saltwater mix-are made up of many different types of habitats. These habitats can include oyster reefs, coral reefs, rocky shores, submerged aquatic vegetation, marshes, and mangroves. There are also different animals that live in each of these different habitats.

Detailed explanation-3: -The diversity of habitats enclosed in estuaries supports enormous abundance and diversity of species e.g. fish, shellfish, lobsters, marine worms, reeds, seagrasses, mangroves, algae, and phytoplankton. Visiting species include birds which roost and feed, pelagic fish to spawn and use as nurseries.

Detailed explanation-4: -Salinity levels in estuaries typically decline in the spring when snowmelt and rain increase the freshwater flow from streams and groundwater. Salinity levels usually rise during the summer when higher temperatures increase levels of evaporation in the estuary.