One of the most poplar examples of commensalism is the relationship between cattle egrets and livestock. The cattle egret is a common species of heron that is found in most regions of the world, and is mostly seen moving along with herds of cattle. This bird moves about in pastures, and follows livestock such as cattle and horses.
Can't be gravitational, due to the fact that atoms are way too small to have a gravitational pull for something of similar size.
The strong nuclear force is the answer you're looking for.
Answer: They do affect the health of an ecosystem.
Explanation: In an ecosystem there are many things that are biotic and abiotic. For an example: water is abiotic and plants/animals are all biotic, the water is not living but it keeps the ecosystem alive by quenching the thirst of the plants growing from the ground and the animals roaming around on the land. Dead animals and plants are not abiotic and they are now providing food for fungi and bacteria. Without the abiotic factors, it would be difficult for the biotic to survive.
Answer:
it would be all of the above