Great question. Increase in atmospheric carbon dioxide is causing acidification of the oceans and this is a threat to animals like starfish because their skeletons are made of calcite, which dissolves in acid. So there is a real concern that animals like starfish may be adversely affected by global environmental change.
That’s quite difficult to say. We are scavengers (we eat everything going but mostly find it easiest to sniff out dead things!) so we could be affected by overfishing. If humans remove too many fish from the shallow waters it could leave us less food to eat and our population is likely to decrease.
We’ve also recently learned that microplastics are found in the stomachs of deep-sea animals so all the pollution that is happen in the surface of the sea is affecting the deep sea too! This could also have a negative impact and reduce our population size.
It is hard to say as very little research has been done on this aspect. But there are indications that global warming will affect their reproduction speed and larval survival and ultimately ocean acidification will have detrimental effects on their ability to make their shells.
The number of twisted wing flies depends in its host numbers as it live a large part of its life cycle in the host. So if due to human interference such as global worming the host numbers are reduced then the numbers of twisted wing flies will also reduce.