The question posted was to draw attention to the coral heads
on the sandy substrate since they were obviously dead or dying.
'When they're sitting on a live, healthy coral head
, if a predator comes by, they just retire into shelter,' she says.
If sinking or downward swimming behavior occurs rapidly and enhances transport of larvae into a reef, then larvae could remain in the cue-laden water within coral heads
sufficiently long for metamorphic induction to occur (Hadfield and Scheuer, 1985).
"There are a lot of coral heads
out here," he said, "and a lot of the beaches haven't had hydrostatic testing done to ensure safe landing areas for the utility landing craft (ICUs).
The sensitivity of corals to increases in C was demonstrated by Mitchell and Chet (1975) with coral heads
exposed to low concentrations of various substances, including crude oil (100 ppm) and organic matter (1000 ppm, in the form of dextrose), under controlled laboratory conditions.
It's nice to be in a living aquarium again, with big coral walls and bommies (coral heads
) and canyons littered with fish: There are purple starfish and cushion-like sea cucumbers, trigger, trumpet, red emperor and unicorn fish, and lots of bright juvenile fry hugging the reef for protection.
The size of coral heads
and the community biology of associated decapod crustaceans.
Many trawls, called roller trawls or rockhoppers, have large rubber discs or steel bobbins that ride over boulders and coral heads
, which might otherwise snag the net.
Says Miller, "Habitat destruction and overfishing have set in motion a population explosion of damselfish." And three spot damselfish have shifted from branching coral to more sensitive coral heads
as disease has wiped out much of the elkhorn and stag- horn coral formations.
Adults shelter opportunistically in reef crevices (three-spot dascyllus) or in live coral heads
(yellow-tail and humbug dascyllus) (Allen 1991).
The colorful bluish-green or yellowish-orange fish are best harvested in the summer by trapping or gillnetting along sheltered lagoons or among low-waterline coral heads
But fragile reefs are suffering damage from many sources including the anchors of dive and snorkel boats at popular sites (such as Molokini Crater, off Maui)--as well as from divers and snorkelers who unwittingly step on coral heads
, or break them off as souvenirs.