Which of the following best describes succession? a. the changes in species composition in a community over time as species colonize and area. b. the evolution of species through natural selection to becomes different species over time. c. all of these are good descriptions of succession. d. the reduction of biodiversity of an ecosystem over time.

Succession is a process which brings change in the composition of species in a community over a period of time. In this process a community undergoes change for the initial colonization of a new habitat. Succession begins with colonization of an area that has not been previously occupied by an ecological community. Succession continues till the climax community occupies that area.

poor water quality affects most estuarine organisms, including commercially important fish and shellfish. the pollutants that have the greatest impact on the health of estuaries include toxic substances like chemicals and heavy metals, nutrient pollution (or eutrophication), and pathogens such as bacteria or viruses.