CORDIO Status Report 2000

East Africa – Summary
DAVID OBURA
CORDIO-East Africa, Mombasa Kenya
East Africa, comprising Kenya, Tanzania, Mozambique
and South Africa, was greatly affected by coral bleaching
and mortality as a result of the 1997-98 El Niño.
Bleaching most probably started in East Africa in late
February – early March, in the south, and finishing in
May in the north, following the movement of the sun
and the Inter-Tropical Convergence Zone. At any single
location, surface water temperatures were raised for
about 2 months, with severe bleaching for 6-8 weeks
progressing into mortality up to 4 months later. While
many shallow reefs suffered mortality levels of > 50%,
some exceeding 95%, there were significant areas with
low coral mortality of less than 20%. Recovery of affected
reefs to the beginning of 2000 has been slow, and
principally through growth of surviving colonies as coral
recruitment rates have been low.
The country summaries presented here are extracted
from the chapters in this volume.
SOUTH AFRICA
South Africa’s reefs lie between 26 o S and 27 o S and are
the southernmost reefs in the western Indian Ocean.
They are generally deep (> 8 m) and on offshore, high
energy banks, with normal sea temperatures ranging
between 22 o C and 26 o C, and not exceeding 29.5 o C. Forty-four
genera and 132 species of hard corals have been
reported, though soft corals dominate the reefs. Bleaching
due to the El Niño was very low, at < 1%, and full
recovery was reported. The depth and high wave energy
of the reefs is likely to have protected them from
greater impacts.
MOZAMBIQUE
Mozambique’s coral reefs are most highly developed in
the north (from 17 o S northwards), with isolated reef areas
and coral communities on the southern coast from
Bazaruto (21 o S) to the South African border. Together
with southern Tanzania, the northern Mozambican
coast is likely to be the center of diversity of the East African
reef fauna. Coral bleaching and mortality due to
the El Niño was highly variable among sites surveyed,
with most sites in the north registering 30-80% mortality
of corals, and in the south, 0-20%. Coral cover following
mortality is noticeably higher inside Marine Protected
Areas than outside. Algal cover now dominates most
reef areas, with no coral recruitment noted indicating
slow recovery. Baseline data on invertebrate and fish
populations have been recorded in 1999 for monitoring
of long term effects. Coral reef monitoring in Mozambique
is being conducted in the context of a National
Coastal Zone Management Program.
TANZANIA
The entire Tanzanian coastline supports coral reefs,
form 5 o S - 11 o S. Coral bleaching and mortality were recorded
along the entire length of the coastline, though at
varying levels. Reefs that suffered the highest mortality
levels of about 80% included Mafia and Pemba Islands.
The majority of reefs were recorded with mortality levels
of about 50%, including islands south of Zanzibar
town and in southern Tanzania. A number of reefs
showed very low mortality, and even increases of coral
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