What are two causes for variation in temperature and salinity of an estuary?

Two main causes for variation in temperature and salinity of an estuary are freshwater inflow and tidal actions. Freshwater from rivers and precipitation can lower salinity levels, especially during periods of high runoff, while tidal movements bring in seawater, increasing salinity. Additionally, temperature variations can arise from seasonal changes, with warmer months leading to higher temperatures, and varying weather patterns affecting local conditions. These factors create a dynamic environment that influences the estuarine ecosystem.