Marine Atlas: Maximizing Benefits for Vanuatu

There is also seasonal variation in photosyn- thetically available radiation in Vanuatu. The greatest variation occurs in the very northern part of the Vanuatu’s waters, where photosyn- thetically available radiation varies by up to 20 per cent throughout the year. This is in part due to changes in atmospheric conditions, such as cloud cover. In Port Vila, the average percentage of the sky covered by clouds experiences signifi- cant seasonal variation, with the cloudiest days occurring from December to March and the least cloudy days from June to September. The chlorophyll-a concentration in Vanuatu’s wa- ters is generally very low, with concentrations in its offshore waters less than 0.1 gram per m3 of seawater. Most of the tropical regions of the open oceans have similarly low chlorophyll-a concen- trations. In contrast, within temperate and arctic regions, these concentrations can approach 1 gram per m3 of seawater. The shallow coastal regions of Vanuatu have slightly increased chlo- rophyll-a concentrations, with up to 0.4 grams per m3 of seawater. Again, this is low compared to many coastal regions around the world, where chlorophyll-a concentrations can reach over 10 grams per m3 of seawater. The low concentra- tions of chlorophyll-a in Vanuatu’s waters reflect the low availability of key nutrients. Compared to large continental landmasses, with large river dis- charges that can carry nutrients into the sea, Va- nuatu is a small island nation with comparatively small nutrient inputs into the marine environment. However, at the local or bay scale, nutrient inputs may still be significant. In the south-western tropical Pacific Ocean, strong seasonal and inter-annual variabilities in the chlorophyll-a concentration have been ob- served (Dupouy et al., 2004). Strong chlorophyll-a enrichments have been documented around the Solomon Islands, and between New Caledonia and Vanuatu, with weaker enrichments found around Fiji or Tonga. The annual variation in chlo- rophyll-a around Vanuatu is low, with variation of less than 2 grams per m3 of seawater in some coastal areas.

Bloom of Trichodesmium erythraeum in the South-West Pacific Ocean between New Caledonia and Vanuatu.

CHLOROPHYLL A CONCENTRATION (milligram/meter 3 )

0.15 mg/m 3

0.04 mg/m 3

Vanuatu Provisional EEZ Boundary Boundary as deposited at UN Archipelagic Baseline No Data

15°S

100 50

200 km

Sources : Becker et al, 2009; Claus et al, 2016; NASA Goddard Space Flight Center, 2014; Smith and Sandwell, 1997. Copyright © MACBIO Map produced by GRID-Arendal

20°S

25°S

Euphausia superba, phytoplankton from the Antarctic, is an example of the basis of the marine food chain.

165°E

170°E

MAXIMIZING BENEFITS FOR VANUATU

SUPPORTING VALUES

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