Chapter I Intro & Objectives - SPREP

PHOENIX ISLANDS PROTECTED AREA MANAGEMENT PLAN
Chapter III. Background, 1. Physical Setting of the Islands
Draft 1 March 2007
on the lagoon side was sand. There were a few sandy beaches primarily on the northeast
coast.
A satellite image of Abariringa (Kanton) is provided in Figure III-1.1 below.
Figure III-1.1. Abariringa (Kanton),
A – Satellite image (source: http://en.wikipedia.org/wiki/Kanton_Island);
B- Chart (source: U.S. Government Chart of 1946).
A B
Lagoon – The lagoon was up to 18 m (60 ft) deep (Bunker 1951; 18 to 22 m (3 to 12
fathoms) according to Hydrographic Office 1916). Large coral heads and reefs inside the
lagoon limited navigation within the lagoon. The lagoon was navigable only by boats with
very shallow drafts 0.3 to 0.5 m (1 to 1.5 ft) (Hydrographic Office 1940). The lagoon was
about 52 square km (20 square miles) (Bryan 1974). It was about 6.4 by 14.5 km (4 miles by
9 miles) (Freeman 1951).
During 1938 to 1939, much of the southwestern portion of the lagoon was dredged in
preparation for the seaplane landings (Bryan 1974).
The water in the lagoon had higher salinity than in the ocean (Van Zwaluwenburg 1941; see
also Wiens 1962). Open ocean water was 20,300 mg chlorine per liter (Degener and
Gillaspy 1955), while the lagoon backwater was 90,000 mg chlorine per litter.
In 1973, the U.S. Naval Undersea Research and Development Center commissioned an
environmental survey of Abariringa’s (Canton) lagoon (Smith and Henderson (1976 and
1978). Water exchange was by tidal flushing that was most efficient near the single pass. In
other parts of the lagoon, flushing was by tidal and wind mixing. Evaporation in the back
lagoon exceeded rainfall producing salinities of 40 ppt, 4 ppt over oceanic values.
Water entering Abariringa’s (Canton) lagoon) was nutrient rich (Smith and Henderson 1976
and 1978). By the time water reached the back lagoon, nutrients had been depleted to almost
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