There are 2 scientific studies testing the effect of a drug on the immune system of AIDS patients. Both studies use the scientific method and are published in scientific
journals. In each study scientists give the drug to one group of people and a placebo
to a second group of people. Both studies measure how many times the patients get
sick over the next year. One study has high variance in the dependent variable
(number of times a person was sick). One study has low variance in the dependent
variable. Which study has statically significant results?

estuaries are the partially enclosed coastal bodies of brackish water formed at the mouth of sea where river meets an ocean. it is a transition zone between river and sea water so estuaries are influenced to both marine environment such as tides, waves and to riverine such as flow of fresh water and sediments. the mixing of sea and fresh water provide high level of nutrients, making estuaries a high product habitats.

many estuaries suffers degradation from a variety of human activities like erosion from deforestation, overgrazing, overfishing, drainage and eutrophication.

so from the above statement answers will be

1. false as estuaries are formed due to both brackish and freshwater.

2.true, due to high productivity estuaries are breeding ground for many marine species.

3. direct and indirect activities of man that contribute to pollution and deposition of sediments.