Blue Abyss is our next topic and BBC Teach has loads of resources arranged by age group and subject which maybe of some help. Below is a link to Blue Planet Live which explores what constitutes a healthy ecosystem and discusses the threats to our oceans such as plastics and overfishing..
https://www.bbc.co.uk/teach/live-lessons/blue-planet-live-lesson/zn7tkmn
https://www.bbc.co.uk/teach/live-lessons/blue-planet-live-lesson/zn7tkmn