let's say there is pollution in the south atlantic ocean, and much of the marine life is harmed; none of the pollution manages to reach the UK shores; but how are UK marine life affected by this damaged marine life elsewhere?
I was thinking maybe because food webs extend across the whole sea and have a knock on effect? Can you give any examples involving UK marine life which is likely to be affected if this were to ever occur?

I've always wondered how something so far from home can affect local life.
thanks :)

I am sure what you say is correct and as climate change and its global effects become more obvious then many examples will come to the fore. Certainly fish migration and effects of sea temperature changes and pollution on krill populations (for example) will have very considerable long-range effects.

I'll be interested to see if others can come up with other or more specific examples - I am sure there must be many!