Please get out your map from yesterday a piece of paper, and read the board.

Freshwater inflows from rivers and bayous meet saltwater from the Gulf of Mexico

Fresh + Salt = Brackish water

List 1: Dissolved Oxygen Tides Wind speed and

direction Salinity Water depth

List 2: Brown shrimp Oysters Chord grass Dolphin Blue crab Red drum

Freshwater inflows from rivers and bayous meet saltwater from the Gulf of Mexico

Fresh + Salt = Brackish water

On your map, add shading: more blue near mouth of rivers and bayous,

More yellow at mouth of Bay

Trinity River – 54% inflow

San Jacinto River – 28% inflow

Add these numbers to your map!

Salinity is one factor that determines where marine organisms breed and live. Some organisms prefer less salty water, while others prefer more salty water.

Juvenile blue crab - 0.0 - 0.5 ppt salt

Oysters - 0.5 - 15.0 ppt salt Lady fish- 25.0 ppt salt

All organisms have a limit for abiotic factors in their environment. Each organism has a range of tolerance for EACH abiotic factor.

Salts are compounds that dissolve in water easily. They occur naturally in soils. Rain water dissolves salts in the soil as the water runs off into streams, rivers and bayous. Eventually, weak solutions of salt reach the ocean. When water evaporates from the ocean, salts are concentrated in the sea water.

The next time it rains, more slightly salty water is carried to the ocean. Over millions of years the oceans have become quite salty. If 1,000 grams of sea water is evaporated, 35 grams of salt are left. This means that 35/1,000th of the weight of sea water is salt. We could also say that sea water contains 35 parts per thousand (ppt) of salt.

Blue water = salty Colorless = fresh

What happens when they mix?

Natural Human caused

1. Which is more dense – salt water or fresh water?

2. What river contributes the greatest amount of fresh water in Galveston Bay?

3. Why couldn’t a juvenile crab live at the mouth of Galveston Bay?

4. List three abiotic factors that affect organisms in an estuary.

5. Why is the ocean salty?