The observations made in “BRAVO" and other large bomb craters indicate
virtually no coral or reef fish recovery. Coral colonization is obviously
inhibited by the abundance of fine sediment and the steep unstable slopes of
the crater walls (45-60°). The bottom of the craters could not be observed
but were deeper than 100 feet to 150 feet. Recent observations in the lagoons
of Bikini and Enewetak Atolls (Colin et al in press) suggest that callianassid
Shrimp may be common in the bottom of the deeper Bikini craters. Reef fish
populations were very reduced due to lack of food or shelter, and the few fish
seen were aggregated near a few small ramose corals (Acropora) and beyond the
upper lip of the craters.
lip of the craters.
The most common alga was Halimeda beyond the upper
The lagoon shorelines of all islands and reefs between Aomen and Bikini
seemed disturbed, possibly by shifting sands or by recent high wave activity
from the south. To a lesser extent the lagoon sorelines between the southern
end of Bikini and southern Eneu were also disturbed, and large piles of coral
rubble and shingle were noted just off the lagoon edge of the interisland reef
flats between the two islands; these deposits may be accumulating from
periodic heavy wave action, either from the lagoon or ocean side. Coral
abundance was low except on the side of pinnacles and patch reefs offshore
from the atoll reef rim or islands. Fish populations, however, were large,
especially edible species of snappers, groupers, jacks, squirrelfish, and
surgeonf ish.
The ocean reef flats opposite Bikini and Eneu Islands and the reefs
between the islands appeared to be healthy and representative of similar reefs
reported at Bikini by Wells (1954) and elsewhere in the Marshalls. All these
reefs show a predictable sequence of zonation; starting from the ocean reef.
edge the following major ecological zones were reported along all sites
observed:
1) coralline algal ridge; 2) a highly productive filamentous /turf
algal zone on the outer reef; 3) a mixed coral and filamentous algal zone at
midreef; 4) a dead coral and thin sediment (or a scoured reef) zone at the
back reef, and a thick sediment or rubble zone beyond the back edge of the
reef flat. Many major groups of reef fishes were seen on the reef flats
including parrotfish and surgeonfish in the front side and goatfish,
rabbitfish, and mullet near the backside.
In addition, subtidal beachrock
formations around all the islets and islands (including Bikini and Eneu) were
primarily sites for schools of surgeonfish, goatfish, rabbitfish, mullet, and
sea perch, and suitable for easy capture by thrownet at low tide.
Giant clams
and oysters were also common on some of the interisland reef flats. The most
common reef corals on the flats included Palythoa, Pocillopora, Montipora, and
Acropora in the front wave washed zones, and the brain coral! Favia and
microatolls of Porites and Heliopora in tne back reef zones.
Greater development of live coral lagoonward from the lagoon edge of the
reef flat was inhibited by sand and rubble deposits. Large growths of the
filamentous blue green algae Lyngbya were reported along many lagoon reef
slopes and reef flats between aoe and Bikini Islands. This algae is
probably seasonal and may be a good indicator of disturbed environments,
possibly caused by periodic heavy wave action from the south (lagoon),
shifting sand, or reduced water clarity near the shoreline or lagoon reef edge.
D.
I000140
CULTURAL RESOURCES.