Different types of macroinvertebrates have different requirements to survive. Some require cooler temperatures, relatively high dissolved oxygen levels or certain habitats. Other macroinvertebrates may be able to survive in less-than-ideal conditions - where there are low dissolved oxygen levels or more sediment - or where the water temperature is warmer. Again, there aren't any "bad" macroinvertebrates, but the population present may indicate that there are bad stream conditions in which only the "strong" can survive.