Sacculina carcini is a barnacle that attaches to the underside of the green crab. The bamacle finds a hole in the green crab's exoskeleton, then uses microscopic hairs to feed on nutrients from the green crab's blood. The bamacle
also lays its eggs in the green crab reproductive system, which sterilizes the green crab.
Which term describes the role of S. carcini in this relationship?

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.

affects the water bodies: excessive use of fertilizers causes eutrophication. the fertilizers which are used on plants affect the quality of land on which it is used, further causing erosion of soil. the fertilizers used on plants contain harmful chemical fumes which affect the environment.

to figure the total magnification of an image that you are viewing through the microscope is really quite simple. to get the total magnification take the power of the objective (4x, 10x, 40x) and multiply by the power of the eyepiece, (usually 10x)