What’s the biggest change to San Joaquin Valley ecosystems caused by humans in the past 150 years?

the biggest change to San Joaquin Valley ecosystems caused by humans in the past 150 years is the shortage of water in the river.

Explanation:

During 150 years, the San Joaquin Valley ecosystems was extremely damaged by the human activities such as building of dams and diversion of river. The San Joaquin Valley has a productive agriculture land due to availability of water. Due to building of dams, the amount of water in the river is decreases and also the population of many fish species decreases. this is because of the disturbance occurs in their natural habitat due to human activities.

answer; i believe the answer is (polygenic inheritance;

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.