Our Blue Planet

When astronomer Carl Sagan first imaged Earth using Voyager 1’s cameras, he referred to planet as ‘A Pale Blue Dot’. His observation accurately described the fact that 70% of Earth’s surface is covered by water. Of all the water, an enormous 97% of the water is marine, with only 3% attributed to freshwater sources such as lakes, rivers, glaciers and ice sheets.

Marine ecosystems

Marine ecosystems are aquatic environments, characterised by high concentrations of sodium chloride. These ecosystems are usually located near or in the ocean. The numerous combinations of bioitic (Living) and abiotic (non-living) factors is the defining variable behind the number of unique marine ecosystems. Examples of marine ecosystems include nearshore systems, such as the salt marshes, mudflats, sea grass meadows, mangroves, rocky intertidal systems and coral reefs. Extending outwards from the coast are offshore marine ecosystems, such as epipelagic surface waters, pelagic ocean waters, the deep sea, oceanic hydrothermal vents, and the sea floor.

In each one of these marine ecosystems, the biotic and abiotic factors vary considerably. For example, between coral reefs and mangroves, there are great differences in biotic factors including predator-prey interactions, bioturbation, mutualism and symbiosis. Likewise, significant differences exist in abiotic factors including photoperiod, dissolved nutrients and turbidity

These factors are why some marine ecosystems achieve high biodiversity. Occasionally, the biodiversity rivals that of terrestrial ecosystems, like tropical rainforests.Coral reefs of the world demonstrate this point clearly, occupying approximately 0.1% of the world’s ocean floor but account for 25% of all marine species. A vast array of diversity can be found in not just the coral reefs but in all marine ecosystems across the planet. Exploring the marine world has taken centuries and we are still making new discoveries every day.