Chesapeake Bay Notes

Estuary - a semi-enclosed body of water that has: 1 Estuary - a semi-enclosed body of water that has: 1. a major fresh water inlet 2. an opening to the open ocean The Chesapeake Bay is the largest estuary in the USA. The Bay is also the most productive estuary in the USA.

Unique Features Estuarine Depth, mixing H2O, temperature=a stressful, yet rich, environment. Productivity Nursery/Spawning grounds Wetlands

Estuaries Salinity - the measure of how much salt is in the water Range - 0 parts per thousand (ppt) – 32 ppt 0.0-0.5 ppt = fresh water 0.5-5.0 ppt = slightly brackish water 5.0-18.0 ppt = moderately brackish water 18.0-32.0 ppt = extremely brackish water +32.0 ppt = salt water

Brackish means a mix of fresh and salt water This is a salinity gradient down the length of the estuary (Bay). It is fresher at the northern ends and becomes increasingly saltier as one travels south. The same is true for the rivers that feed the Bay itself.

Variations in Salinity- Cause a stressful environment. WHY? -animals in the estuary must be able to adapt to increasing and decreasing levels of salt (salinity). -salinity changes are due to the season weather patterns Spring =more fresh water coming into the bay=lower salinity in the bay.

2. Fall = little rain over summer and fall = little freshwater inflow = higher salinity in the bay. Tides also play a major role in salinity levels. Every six hours the tide is wither at low or high tide. Generally the pattern is salt in on the bottom and fresh water on top. This is not always the case and organisms must be able to adapt to theses constantly changing salinity levels.

The brackish nature of an estuary allows for a larger number of organisms to hang out in its waters. A bucket of fresh pond water and a bucket of ocean water will only yield a few different types of organisms because its salt- fresh water mix.

2. Depth, mixing H2O, Temperature = a stressful, yet rich, environment The average depth of the Bay is only 21 ft. deep. For most of the Bay, a six foot tall person could walk around in the water and never have to hold their breath. This shallowness is good at times, at other times bad, and sometimes even downright ugly, for the critters that call the Bay their home.

The Good shallow water is good for SAV because it allows the underwater grasses to make lots of dissolved oxygen (D.O.) for underwater organisms. Lots of sunlight being able to reach the bottom also allows for larger amounts of grass to grow. These SAV are a source of food, shelter, and even serve as nurseries for underwater organisms. The shallowness of the water of the water also allows for easier mixing of nutrients for plant life and phytoplankton for animal life.

Phytoplankton is microscopic, which means you need a microscope to see them. Just because they are small does not mean they are not important. In fact they produce over 70% of the world’s oxygen supply. They are also primary (1 degree, 1°) producers which means they are at the bottom of the food chain just like other plants. They get their food from the sun just life a tree or rose bush.

Equation: shallow water= lots of sunlight = lots of grasses =lots of oxygen = lots of underwater wildlife The Bad - Shallow water also causes a great deal of stress for the organisms that call the Bay their home. In fact, some say the Bay is a great place to like is you can stand ride. Some problems that occur with shallow water are:

1. The Bay heats and cools rapidly- Due to depth; water is mixed a great deal. Top water becomes bottom water and vice versa. A cool Bay on a hot day does not remain cooler for very long. The same is true when a cold front comes up real fast and the water temperature can drop drastically. This is not a stable environment for organisms. For one thing, oxygen levels are higher in colder water. Some areas of the Bay during the summer have no dissolved oxygen at all due partly to high temperatures.

2. The shallowness of the Bay also allows the bottom silt to get mixed into the water column especially during stormy or windy weather. This silt blocks sunlight to SAV which reduces DO levels. The fine silt also interferes with small fish and their ability to get oxygen because it clogs their tiny gill pieces.

The Ugly - If oxygen levels decline; the area can become one of two classifications: Hypoxia - low levels. Few organisms can tolerate theses levels of oxygen. Those organisms that can leave, do; those that cannot become stressed. Anoxia - no DO. Few organisms can tolerate this zone for extended period of time.

Productivity The Bay is enormously productive in the following: 1. Detritus - Bits of decaying plant and animal matter suspended in, or at the bottom of the Bay. Detritus is the muck you sink in but it is also somebody else's food. 2. Freshwater inflow provides nutrients for the production of Bay plants. (Primary producers, 1°) which becomes detritus when they die.

3. Three classes of 1° producer in the Bay estuary: A 3. Three classes of 1° producer in the Bay estuary: A. algae - attached to the bottom B. marsh grasses - found in semi-flooded area or wetlands C. phytoplankton - suspended in the water column. All of these 1° produces can support many fish, mammals, reptiles, birds, amphibians, and invertebrates, such as crab and shrimp.

Primary production comparison: 1. 1 acre of marsh estuary producers 10 tons of plant matter/year 2. 1 acre of wheat producers 1.5 tons plant matter/year This all means that the food chains in an estuary are very large and the webs are very diverse.

Nursery/Spawning Grounds Estuaries serve as nurseries for many organisms. Why would an estuary attract mothers to have their young and then keep the young there to grow and develop?

Estuary provides a tremendous food source to nourish both the young organisms and adults alike. The food available is marsh grasses, phytoplankton, and algae, as well as small animal life. The small animals include invertebrates such as zooplankton, shrimp, and crabs. Small fish are also available. Estuaries provide shelter in the form of submerged grasses and the shallowness of their water. Lager predators cannot get into the grasses or shallow water to their food, especially at high tide.

Wetlands Wetlands are areas that surround the Bay that are vital to the survival of the estuary. Wetlands are not limited to salt marshes. They can be swamps, cattail marshes, bogs, or any area that has water.

3 Functions of a Wetland: 1 3 Functions of a Wetland: 1. Flood Control/Erosion Control slows down the flow of rainwater into the bay. 2. Natural Filter - acts as a sponge and traps pollutants and sediments so the bacteria in the water can decompose them. 3. Provides Habitat - a large number of organisms call wetlands their home. This provides a stable and long food chain for healthy ecosystem.