How do fish make homeostasis?

Answer 1

Why aren't we seeing a lot of marine life in certain parts of the Gulf of Mexico? You don't have to be a doctor to answer this question, but you do have to have some scientific tools to diagnose the problem.

On the Oregon II, a device called a CTD is used to take measurements such as conductivity (salinity), temperature, chlorophyll concentration, and dissolved oxygen (DO). These water quality measurements let researches know what's happening in the water just like a doctor would look at your test results to gage your health status. Sometimes a doctor may need to do a second test just to confirm the results. NOAA's fisheries biologists do the same thing with their water quality assessments. Winkler titrations and a hand-held Hack Dissolved Oxygen meter are used to confirm the dissolved oxygen readings from the CTD. Scientists need to make sure the data they collect is accurate and the more tests they perform the better their data will be.

This large piece of equipment is a CTD sensor. The top portion of the machine contains three gray vertical cylinders which are used to collect water samples. Under the machine are sensors that test the water quality while it is submerged. Here I am washing out the sensors once it was brought back on board from a test.

When comparing data from this device to our trawl samples, it's obvious that water with low levels of dissolved oxygen can not support much life.

Dissolved Oxygen: Marine animals need oxygen to survive just like land animals do. The main difference is that most marine animals have gills which are able to diffuse oxygen molecules from the water directly into their blood. Diffusion is the process of a molecule moving from an area of high concentration to low concentration.

Have you ever sprayed air freshener and noticed how the smell moves from where you sprayed it (high concentration) throughout the entire room (low concentration) until the smell is equally distributed throughout the room (equilibrium)? That's how diffusion works.

It's very important to understand that the amount of dissolved oxygen MUST be higher in the water then inside of the animal's body or diffusion of oxygen into the blood won't take place. This means the animals will either have to move or die. This is what's happening in the "Dead Zone" in the Gulf of Mexico.

The reason levels of oxygen are so low in the Gulf of Mexico are due in part to human actions. The overuse of fertilizers that are high in nitrates and phosphates are one of the major problems. When it rains or floods, these extra nutrients wash off of our lawns and into storm drains which then drain into the rivers. Most of the Mississippi watershed consists of agricultural land in the breadbasket of the Midwest where a lot of fertilization takes place during the spring and summer months. All of the nutrients from the rivers in the Mississippi watershed eventually empty out into the Gulf of Mexico.

Answer 2

Fish are ectotherms, meaning their internal temperature depends on the temperature of the environment.