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Water for Life
Life on Earth is dependent on clean water. Water quality is defined as the stability of water for a particular use. A definition of good water is different for drinking water than for a lake. Because water is so important for life, we monitor different chemicals and physical and biological characteristics and work to ensure good water quality.
Water, Water Everywhere
Water in the ground, called groundwater, is an important source of water on Earth. The ground is different in different places, and some ground materials hold water better than others. An aquifer is an area of ground that holds water well/. Water moves into the ground from rain, snow melt, or other sources. Then it sins until it gets to a layer it can’t move through. This layer might be clay or certain kinds of rock.
Water can fill aquifers, where deep water might remain for hundreds of years, and shallow water can flow to places where it reaches the surface, like ponds, lakes, and springs.
There is much more freshwater in the ground than on Earth’s surface, and groundwater is drawn out using wells.
Water Quality=Quality of Life
To evaluate a pond’s ability to support life, we might measure characteristics like the following: dissolved oxygen(DO)-because fish and most other aquatic animals breathe DO: PH-if pHis too far from neutral, either acidic or basic, organisms may be unable to survive; water temperature-warmer water holds less oxygen, so animals might avoid areas of high temperature. In this pond, at certain times, we might also check salinity (the salt concentration).
Freshwater has a salinity of 0 ppt (parts salt per thousand parts water). When Dauphin Island is hit by a hurricane, saltwater may wash over parts of the island and enter the pond or the groundwater. This can affect the island’s human population, who use groundwater in their homes, and also the animals that live in the pond.
These are just a few examples of water qualities that might affect those using the water.
At Gaillard Lake, you can see where the water table becomes a like surface. When you look at the lake, can you tell oxygen, pH, temperature, or salinity levels? Does the water look dirty?
You may not be able to determine levels by looking, but if you pay attention, you might notice hints bout a lake's water quality. Can you find a diversity of fish, turtles, alligators, frogs, or insects in the water? Are birds feeding from the lake? These signs suggest good water quality, but they are not definitive-sometimes animals are forced to use poor-quality lakes. Water cooler is not a definite marker either - this lake is often a brown color, like tea. This is natural. It is from tannins that leach out of soaking leaves or pine needles.
Aquatic invertebrates are used to assess water quality. Some, like those seen above (larvae of left to right: caddisfly, stonefly, and mayfly), have a low tolerance for pollution. If they are found in a sample, the water quality is likely good. Others, like the pouch snail and mosquito larva at left, have a high tolerance for pollution. If a sample has mostly animals like these and very few of those from the first group, water quality is likely poor.
In the U. S., for water intended for human use, there are established standards for acceptable levels of dissolved or suspended matter, like bacteria, heavy metals, and others that are potentially harmful. Our municipal water usually follows a path such as this one: water is withdrawn from a natural source, filtered and sterilized, piped into our homes; flushed down our drains; filtered, treated, and the solid waster is taken to one disposal site, while the water is released back to a natural location. Water used in homes on Dauphin Island is groundwater from the island (it is not piped in). Processed water is stored in the water tower seen at right.
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| Nature Interpretive Trial at Dauphin Island
Nature Interpretive Trail
Audubon Bird Sanctuary Trail
These yellow sections of the trail to the Gulf and around the lake include several signs to help the visitors better understand and appreciate the unique environment of the Audubon Bird Sanctuary.
Mike Henderson Project Supervisor. Additional identification by Ralph Havard, McCune Dudley, and John Porter
Signs construction/installation-Greg Vesely, Candy Ladnier, Anthony Young
Please Help Protect your park
The Dauphin Island Park & Beach and Alabama State Lands
Department of Conversation and Natural Resources
Funding for this project in part by the Coastal Zone Management Act 1972
As amended, administered by the Office of Ocean and Coastal Resource Management, National Oceanic and Atmospheric Administration
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| Foreign Invasion
Organisms that arrive in an ecosystem where they did not evolve are called exotic, non-native, or alien. Of those, the ones that harm their new ecosystem are invasive. There are several species on Dauphin Island. A few of them are highlighted below.
Infiltration
Plants, animals, and other organisms are moved from their native lands in different ways. These pathways of introduction often involve humans who accidentally or intentionally move them.
A few examples include the release of exotic pets, escape from aquaculture operations, spread from garden plantings, transport in ships ballast water, and transport of fruits and vegetables. As humans move more people and goods around the world, there is more potential for moving organisms into places where they cause harm.
Setting in: Once they are in a new place, some organisms settle in more successfully than others. Certain factors allow an introduced species to become invasive:
They are adaptable-they can survive in a range of climates, habitats, and soil types; they eat a wide variety.
They reproduce quickly and have lots of offspring.
They spread out to new areas
Few animals will eat them in the new habitat.
They competed aggressively for resources.
How does this affect us?
Biodiversity is the variety of life. It can be defined at different levels, from diversity within a species to that in a particular forest to that of the entire Earth. The higher the biodiversity for a given area, the healthier the species or ecosystem because it is more resilient to disease or disturbance, such as fire or flood.
Humans need healthy ecosystems for many reasons. We are healthier with a diversity of organisms for food and medicine. Functioning ecosystems provide important services such as water filtration, oxygen production, and nursery habitat.
Invasive species threaten biodiversity either by directly killing native species or by taking resources from them so they die or stop breeding.
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| Reptiles and Amphibians of the Dauphin Island Bird Sanctuary
Reptiles and Amphibians of Dauphin Island Bird Sanctuary
Galliard Lake and Tupelo Swamp
Cottonmouth
2-4 feet
AKA water moccasin. This poisonous aquatic snake is thick-bodied and will gape to show its white mouth lining when threatened.
Common Snapping Turtle
6-15 inches.
Often confused with the less-common alligator snapping turtle, these turtles are not aggressive unless removed from the water.
American alligator
4-8 feet
Individuals of this large shy aquatic species periodically “raft” to the island from the rivers north of Mobile.
Florida Smooth Softshell
6-15 inches
With its flat, leathery shell, this turtle is easy to dust from others. Its death includes crawfish, insects, fish, and frogs.
Central Newt
2-4 inches
This reclusive salamander prefers quiet pools without fish. The left, a terrestrial intermediate stage, can be found under rotting wood.
Pig Frog
2-6 inches
This large frog inhabits permanent bodies of water surrounded by vegetation.
Their mating call is a distinct, loud, and resonant grunt.
Lists sixes are typical of Dauphin Island representatives
The project was led by Brian Jones, funded by Mobile Bay NEP, and made possible by Dauphin Island Park and Beach Board.
All photographs by Brian Young (“except the alligator photo by Boon Harada) |
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| Nature Interpretive Trial at Dauphin Island |
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| Nature Interpretive Trial at Dauphin Island |
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| Nature Interpretive Trial at Dauphin Island |
