120 



COLIN 



diameter of the colony of about 5 to 6 cm, whereas 

 Pocillopora in shallow water had an annual growth in diam- 

 eter of about 4 cm. Smith and Harrison (1977) reported 

 table Acropora colonies to increase their diameter 15 cm 

 or more per year once they had reached the stage where 

 they transform from a vasiform to tabulate corallum. 



Haggerty (1980) found that with increasing water 

 depth both Fauia pallida and F. stelligera had more widely 

 spaced corallites, a slower linear skeletal growth rate and a 

 decrease in the annual skeletal growth rate per square cen- 

 timeter. Fauia pallida had a hemispherical colony form in 

 all environments at 3 to 41 m depth, but deep water 

 populations possessed more septa per corallite than shal- 

 low water. Fauia stelligera changed its colony morphology 

 with depth, from "lobate or hummocky" in shallow water 

 to "columnar with a slight basal skirt" (Haggerty, 1980) in 

 deeper water. 



Stimson (MPRL, 1973) looked at the interactions via 

 "extracoelentric digestion" between closely adjacent corals 

 of various species at Enewetak. In the hierarchy of 

 Enewetak corals, based on the species which could be 

 successfully "attacked," Astreopora mi/riopthalrna ranked 

 the highest, with Acropora acuminata second, and Pontes 

 lutea third. Pocillopora spp. were lowest, being killed on 

 contact with other species. 



Stimson (1978) studied the timing of planulation by 

 species of Pocillopora and Acropora at Enewetak. He 

 found Enewetak colonies to produce planulae primarily 

 during the new and first quarters of the moon. He also 

 suggested that planulation by Acropora may be more sea- 

 sonal than Pocillopora because about twice as many 

 colonies planulated during the summer than in the winter. 

 Among pocilloporids, colonies 6 to 8 cm in diameter (15 

 to 30 cm in volume) were the smallest observed to planu- 

 late and estimated to be 1 to 2 years old. Acropora 

 colonies as small as 50 cm'' planulated, but most were 

 greater than 1000 cm^ in volume. Pocilloporids generally 

 produced more planulae than acroporids at Enewetak. 

 There can also be geographic variation in lunar timing of 

 planulation. The lunar periodicity of planulation in P. dam- 

 icornis is the same in Palau as Enewetak but is reversed 

 from Hawaii (Stimson, 1978). 



Stimson (1978) felt that shallow-water corals at 

 Enewetak were in a more "disturbed" environment than in 

 deeper water and that species found predominantly there 

 would have high reproductive rates. He has measured 

 annual mortality rates as high as 20% for shallow-water 

 corals. Most of these species produce planulae rather than 

 smaller eggs and may do so to facilitate rapid settlement in 

 the current-swept reef flat areas. 



The large table Acropora (A. hiiacinthus?) produce 

 shaded area beneath them. Stimson and Polacheck (MPRL, 

 1977, 1979) found the shaded area to be less than 1 m^ 

 per colony at 30 to 80 cm from the substrate. The density 

 and number of other coral species beneath table Acropora. 

 both dead and alive, were less than in controlled unshaded 

 areas. The genera of corals occurring in the shaded areas 

 v^ere Stiilocoer)ieUa, Montipora, Seriatopora. and various 



massive species Species of Acropora and Pocillopora 

 piedominated the adjacent unshaded areas. 



Kastendick (MPRL, 1975, 1976) examined the habitat 

 differences among eight species of fungiid corals which 

 grow unattached on lagoon coral pinnacles and patch reefs. 

 The young of two species were attached (Fur\gia fungites 

 and Halomitra pileus) and found almost exclusively at the 

 upper limit of adult distribution. It is likely that as they 

 age, fungiids move passively down the slope. Kastendick 

 observed invasions of colonies onto the foot area of several 

 pinnacles after removal of these corals the previous year. 

 Fur^gia spp. were found exclusively on coral rubble, 

 whereas H pileus was most abundant on sandy substrate. 

 Translocation of individuals up and down the pinnacle 

 slope indicates that F. fungites has the most restricted 

 habitat requirements, with H. pileus less so. 



Storms during the summer of 1972 (Nolan, 1975; 

 Stimson, MPRL, 1974, 1976) destroyed large areas of 

 coral growth on reefs with a southern exposure, even 

 within the lagoon. Only massive species of Porites survived 

 in any quantity on damaged reefs. First recolonizers were 

 Acropora striata and A. s^ringoides. Stimson (MPRL, 

 1975, 1976) also noted that Sarcoph^ton sp., a soft coral, 

 was an important colonist and component of the benthic 

 fauna on storm-damaged reefs. As the hard coral commu- 

 nity recovered, he believed that Sarcoph\^ton sp. would 

 become progressively rarer. It was observed shading many 

 corals, including P, damicornis and Seriatopora hystrix. 



Highsmith (1981a) suggested that corals with high 

 skeletal density are less able to recolonize dead areas on 

 their skeletons by tissue growth than less dense species. 

 For example, he reports Porites lutea. with a relatively 

 low density (1.4 to 1.5 g cm~^), is able to rapidly grow 

 over dead skeletal regions, whereas Goniastrea retiformis 

 (1.6 to 2.0 g cm~^) requires considerable skeletal deposi- 

 tion and polyp growth reorientation to overgrow dead 

 areas. 



Calcareous material produced by organisms other than 

 stony corals is important in both the reef framework and 

 sedimentary material. Animals, other then Scleractinia, 

 which might make a significant contribution are the Fora- 

 minifera, Mollusca, Bryozoa, Sclerosponges, and other Cin- 

 daria. 



The occurrence of foraminifera tests in sedimentary 

 material in the lagoon and beach sands at Enewetak is well 

 documented (Emery et al., 1954; Odum and Odum, 1955; 

 Deutsch and Lipps, 1976). Forams may consititute a sig- 

 nificant percentage of lagoon sediment grains, but they are 

 believed insignificant in reef growrth. Mollusc shells similarly 

 constitute a minor component of lagoon sediments but do 

 not contribute to reef growth. 



Cuffey (1973) found no bryozoans on the coralline 

 algal ridge of Enewetak and very few in the area (which he 

 terms the "back-ridge trough") immediately shoreward of 

 it. The reef flat, similarly, has almost no bryozoa occurring 

 on it. Areas between islands with abundant coral in shallow 

 water also had relatively few bryozoa. Howpver, in the 

 lagoon margin area, where larger patch reefs begin to 



