how the world's ocean waters are linked by currents, tides and water cycles, and how humans interact with this fragile ecosystem.
(the world's ocean waters; are linked; by currents, tides and water cycles, and how humans interact with this fragile ecosystem) (humans; interact; with this fragile ecosystem)
the world's ocean waters humans
are linked interact
by currents, tides and water cycles, and how humans interact with this fragile ecosystem
with this fragile ecosystem