What is it called when a string of islands that forms where two convergent boundaries collide?

When two convergent boundaries collide, especially in the ocean, an Island arc is formed.

When these  two convergent plates collide, the older plate which is denser subducts beneath the younger plate.  As the subducting plate is pushed deeper into the mantle, it melts. The magma this creates rises and erupts. This forms a line of volcanoes known as an island arc , with considerable earth quakes created.

Examples of island arcs include Japan, Indonesia, the Phillipine Islands and the Aleutian Islands  of Alaska.

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.