what is daphnia viability?

Answer 1

Viability is an organism's ability to survive in a given set of conditions.

So, Daphnia viability would measure how fit the organism is. It's probably used in genetic testing, in which certain genes are manipulated so as to understand why they are important. That is, they can "knock out" genes in order to determine what their function is in development, growth and metabolism.

Answer 2

viability= ADJECTIVE: 1. Capable of living, developing, or germinating under favorable conditions. viability, Daphnia are small, mostly planktonic, crustaceans, between 0.2 and 5 mm in length. Daphnia are members of the order Cladocera, and are one of the several small aquatic crustaceans commonly called water fleas because of their saltatory swimming style (although fleas are insects and thus only very distantly related). They live in various aquatic environments ranging from acidic swamps to freshwater lakes, ponds, streams and rivers.
As human population centers grow to cover more and more of the planet, watersheds are increasingly affected by the presence of buildings, roadways, and parking lots. A watershed is "the area of land that catches rain and snow and drains or seeps into a marsh, stream, river, lake or groundwater." (EPA, 2006b.) This project asks the question: "Can run-off from parking lots be toxic to organisms in nearby ponds and streams?" You will learn how to conduct a bioassay to determine if sediments from a parking lot are toxic for aquatic organisms.

As the name suggests, a bioassay uses living organisms as the "detector" for an experimental procedure. When doing environmental testing for toxins, the bioassay is typically a viability assay. You count how many organisms are present at the beginning of the experiment, expose the organisms to different concentrations of the suspsected toxin, and count the number of organisms that remain viable. It is critically important to maintain a control population of the organisms, so that you don't mistake the naturally-occuring death rate of the organisms as the effect of toxins.

The organism that you will use for testing water toxicity is Daphnia magna. Daphnia magna (common name "water fleas") are tiny freshwater crustaceans. They are filter feeders, and can survive in culture by eating algae, bacteria, or yeast.


Figure 1. Photomicrograph of Daphnia, the common water flea.

Answer 3

less than one year, look the link