with its current use by our populations. There is a related question of whether man-made 
marshes would function like natural marshes. 
3. Habitat Substitution — If it is not possible to create new wetlands, alternate habitats like artificial 
reefs could be constructed. It is not known to what extent such a substitution can replace a 
wetland. If we do create new reef areas there is an additional concern about altering the ratio of 
shallow/deep water in the bays. 
4. Submerged Aquatic Vegetation Losses — The cause of disappearance of 90 percent of seagrass 
beds in Galveston Bay is not known. Several of the possible factors range from eutrophication, 
turbidity from freshwater inflow or proximity to shipping lanes such as the Intracoastal 
Waterway to herbicides from agricultural runoff. Seagrasses were previously located in several 
areas of Galveston Bay so the cause may be distributed over the entire estuary. 
5. Relationship to Biota — There are significant populations of waterfowl and larval fishes that 
utilize seagrasses for food or shelter. It is not known whether the decline in seagrass will also 
affect a further decline in these associated organisms. 
Living Resources 
1. Finfishes — The commercial fishing for redfish and spotted sea trout were closed as the 
population declined. The relationship of the combined effects of contaminants, loss of habitat 
and overfishing are not known. 
2. Shellfish — There are several construction proposals that will change the timing and quantity of 
freshwater inflow. Dams level out the water flow with smaller peak flows and higher low flows 
so the prospects of future oyster and shrimp production are uncertain. Predators and disease 
decimate oyster populations if high salinity values occur, while white shrimp populations 
cannot thrive without freshwater flow. A more detailed cause/effect response needs to be shown 
for these impacts. 
3. Resource Recovery — The living resources have declined or are threatened by toxicants, 
pathogens, eutrophication, habitat losses and harvesting. Many of these stresses can be reduced 
with good management strategies but it is uncertain how quickly the biological populations can 
rebound. 
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