If you're can't donate to us or any of these charities, you can still make your own impact without spending a dime.
Make sure all your garbage goes into the right bins. Just throwing your garbage away instead of leaving it on a beach or riverside saves marine animals who might choke on it or eat it by accident.
Don't support things like illegal poaching or overfishing. Many animals are illegaly poached for their meat, hide, bones, and occasionaly just for fun. Not supporting these acts and being aware of them or how to stop or prevent them saves millions around the world. Try to buy fish that was caught within enviormental regulations.
If you have some sort of electric car, non-oil power source or gasless transportation, consider using it more. Leftover oil and other pollutants can make it into the sea, where they both feed the greenhouse effect, heating up the sea, and pollute the oceans, causing plenty of problems. If you don't want to switch to wind or solar, at least use a bus every once in a while to save a car ride.
Besides that, just remember the points made in this document and maintain your ocean awareness!