What will most likely happen to this ecosystem if the swordfish are killed by a virus? and why?

a. it will be harder for sardines to survive.

b. the shark population will decrease.

c. the sardine population will decrease.

d. it will be easier for sharks to find food.

The shark population will decrease. (Ans. B)

Explanation:

If swordfish are killed by a virus in ocean biomass, the shark population will decrease because the shark consume swordfish (which are present in fourth tropical level of food chain in ocean or marine biomass) , so if there is nothing for sharks to eat they will eventually die.  

Biomass is the total mass of living biological organism in an ecosystem at a given time.

try using substitution:

x + y - 6 = x - y. (i'm not giving you the exact answer). since 0 = x - y, then sub 0 in the equation with x - y. combine your like terms, and then use inverse operations, and you'll have your answer.

: -)