Marine Atlas: Maximizing Benefits for Kiribati

the Line group, and decreases to the west, with lower maximum values in the Gilbert Islands. This is a reflection of the local climatic conditions, with the predominant- ly easterly trade winds (see also chapter “Go with the flow”) resulting in changes in increasing cloud cover from east to west. There is seasonal variation in photosyn- thetically available radiation in Kiribati. The greatest variation occurs away from the equator, in the southern areas of the three island groups. There is also greater vari- ability in photosynthetically available ra- diation in the Gilbert group compared with the other two island groups. This is in part due to changes in atmospheric conditions,

such as cloud cover. In Tarawa, the average percentage of the sky covered by clouds experiences significant seasonal variation, with the cloudiest days occurring from De- cember to March and the least cloudy days occurring from April to November. The chlorophyll-a concentration in Kiri- bati’s waters is generally very low, with concentrations in the offshore waters less than 0.15 grams 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 Tonga have

increased chlorophyll-a concentrations, with up to 3–5 grams per m3 of seawater in some of the coastal areas of the Gilbert Is- lands. 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 concentrations of chlorophyll-a in Kiribati’s waters reflect the low availability of key nutrients. Compared to large continental landmasses, with large river discharges that can carry nutrients into the sea, Kiribati 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 variabili- ties in the chlorophyll-a concentration have been observed (Dupouy et al., 2004). Strong chlorophyll-a enrichments have been doc- umented around the Solomon Islands, and between New Caledonia and Vanuatu, with weaker enrichments found around Kiribati or Tonga. The annual variation in chlorophyll-a around Kiribati up to 5 grams per m3 of seawater in some coastal areas.

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

PHOTOSYNTHETICALLY AVAILABLE RADIATION (Einstein m -2 d -1 )

5°N

5°N

51

38

Kiribati Provisional EEZ Boundary

400 km 200 100

0°

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

0°

5°S

170°E

175°E

180°

175°W

170°W

5°S

0°

10°S

5°S

160°W

155°W

150°W

MAXIMIZING BENEFITS FOR KIRIBATI

SUPPORTING VALUES

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