The best book I've read on these matters is The Ocean of Life: The Fate of Man and the Sea by Callum Roberts. It's about 400 pages long and meticulously details

The best book I've read on these matters is The Ocean of Life: The Fate of Man and the Sea by Callum Roberts. It's about 400 pages long and meticulously details our effects on the marine environment (though in an entertaining and accessible manner). We're looking at cataclysmic changes in the oceans. It's not too late to revert course, but overfishing and pollution (acidification, in particular) have already changed our marine ecosystems, and they will continue to do so. Great diversity has been lost, while jellies and other more primitive lifeforms used to less hospitable conditions are now thriving. The bizarre tragedy comes, in part, from the dilution hypothesis: it's commonly accepted that the oceans are really big, so big that they can withstand our meddling. While the oceans are big, they're neither that large nor are they totally homogeneous: there are many marine ecosystems, all of which are fragile. But most of these marine ecosystems are still large enough to change slowly -- too slowly to be immediately noticed by laypersons. The slowness of change in the marine ecosystems makes environmentalism a politically difficult platform: good policies do not yield immediately measurable positive results, and while the threat is grave, it is creeping sufficiently slowly for action to be continuously procrastinated.