Ocean Atlases – Storytelling out of the Blue

The ocean covers more than two-thirds of our planet’s surface. In Fiji, the area of ocean is even 70 times larger than the land territory. With an Exclusive Economic Zone of 1.29 million km2, Fiji is not a Small Island Country, but truly a Large Ocean State.

This is where the Fiji Marine Atlas comes into play. Research has improved over the years, enabling us to better understand the system of our ocean and to develop solutions for dealing with the ocean sustainably. A lot of data has become publicly available. This atlas compiles over hundred datasets from countless data providers and for the first time makes this treasure trove of marine and coastal information accessible and usable – as maps with complementing narratives, as data layers and as raw data.

E-copys are available online FijiTongaKiribatiSolomon Islands and Vanuatu. as well as interactive versions.

Extracts:

GO WITH THE FLOW – SALINITY AND SURFACE CURRENTS

Fiji’s ocean currents are driven by wind, the amount of salt (salinity), and heat in the sea. Salinity and currents affect the distribution of marine life and the climate in Fiji, particularly during extreme El Nino years.

A trip around the world

How long does a trip around the world take? The current record on a plane is 67 hours, and on a sailboat: 50 days. But it took Magellan more than three years (from 1519 to 1522) to be the first to circumnavigate of the Earth. Water in the ocean is not in such a rush, and takes much more time on its journey on the “global conveyor belt”. Within this belt there is a constant motion in the ocean – it is far from being a still body of water. This motion is caused by a combination of thermohaline currents (‘thermo’ = temperature; ‘haline’ = salinity) in the deep, and wind-driven currents at the surface. Cold, salty water is dense and sinks to the bottom of the ocean, while warm water is less dense and remains at the surface. The ocean conveyor ‘starts’ in the Norwegian Sea, where warm water from the Gulf Stream heats the atmosphere in the cold northern latitudes. This loss of heat to the atmosphere makes the water cooler and denser, causing it to sink to the bottom of the ocean. As more warm water is transported north, the cooler water sinks and moves south to make room for the incoming warm water. This cold bottom water flows south of the equator all the way down to Antarctica. Eventually, the cold bottom waters returns to the surface through mixing and wind-driven upwelling, continuing the conveyor belt that encircles the globe (Rahmstorf 2003), crossing the Pacific from east to west. A full circle takes about 1000 years. No rush at all!

VOYAGE TO THE BOTTOM OF THE SEA – GEOMORPHOLOGY

Fiji’s seafloor is far from being a flat empty space. It is rich with physical features in different shapes and forms that are important for the distribution of biodiversity, fishing grounds, and deep sea minerals, but also for risks like landslides and tsunamis.

A slippery slope

An example of how important the slope of physical underwater features is comes from 1953. On September 14 of that year, Fiji’s capital, Suva, was struck by a nearby earthquake (see also chapter “Smoke Under Water”). Different to the 2009 Samoan earthquake, described in the bathymetry chapter, this earthquake did not send a direct tsunami that threatened Fiji or other Pacific Island Countries. However, it did cause a coral reef platform to collapse, which induced a submarine landslide. Sixty million cubic meters of mud, stone, and part of a long-wrecked vessel hurtled to the depths of the Suva Canyon, at the western end of the entrance to the Harbour. This triggered a tsunami, devastating the villages of Nakasaleka and Makaluva, as well as parts of Suva. There were five deaths from the tsunami and a total estimated damage of $500,000 (at 1953 values in U.S. dollars), making it the most destructive earthquake in Fiji’s recorded history (Rahiman 2007; Pacific Disaster Center 2011). Had the tsunami occurred at high tide, it would have been even more damaging.