KEY FINDING 6. Observed changes in marine biodiversity over the past 50 years have been driven by a combination of physical factors and human activities, such as oceanographic and climate variability, and overexploitation. While certain marine mammals have recovered from past overharvesting, many commercial fisheries have not.
The global marine ecosystem dynamic covers over 70% of the Earth's surface. It is a complex system, in constant motion, moving not only nutrients, dissolved oxygen, carbon, and water masses, but also bacteria, algae, plants, and animals, among regions. The millions of species estimated to live in the ocean dwell in a wide range of habitats, including the open ocean, sea floor, sea ice ridges, hydrothermal vents, cold seeps, coral and sponge communities, seamounts, ocean trenches, and continental shelves.1
Marine biodiversity is the foundation of the countless ecosystem services provided by the oceans. Marine plankton plays a major role in the global carbon cycle, and harvest of marine species provides an estimated $21 trillion per year in socioeconomic benefits to the world.2 Marine biodiversity is essential for the functioning of marine ecosystems, their ability to persist under stress, their ability to recover from disturbances, and their ability to provide benefits to people.3 With jurisdiction over 6.5 million km2 of marine waters in three oceans,4 Canada reaps immense benefits from the ocean.
Tidepool, Tofino, B.C.