Hydrology
The Baffin Bay has three branches, which are named as follows (counterclockwise on the map above): Alazan Bay on the north (green), Cayo del Grullo (purple) and Laguna Salada (blue). Several ephemeral streams, including San Fernando, Santa Gertrudis and Los Olmos, flow into the bay, but only when it rains. Because of the scarce freshwater inflow and extensive evaporation, which is promoted by shallow water and warm climate, the bay has a relatively high water salinity reaching 75‰ (parts per thousand) in its northern part. Between 1946 and 1948 and in 1968, the salinity level in the bay exceeded 100‰ killing much fish in the area.
About 21 km2 of the bottom of the bay is covered in seagrass; most other parts are dominated by shoal grass (Halodule beaudettei) with occasional rocky outcrops. Scattered parts of the bay, mostly near the mouth, contain the relict serpulid worm reefs, which are composed of the remains of serpulid tube worms. Although some tube worm species still inhabit the bay area and the reefs, they bring no significant contribution to the reef structure. Most reefs are circular or ellipsoid structures between 8 and 40 meters (26 to 131 ft) in diameter and 0.5 to 2 meters (1.5–6.6 ft) in height above the sediment. Their total area is about 16 km2 (6 mi2), but it is gradually reducing due to erosion.
Read more about this topic: Baffin Bay (Texas)