ECOLOGY OF THE MURRAY ISLAND CORAL REEF. 



25 



In the squares upon this reef-flat 24 genera of corals were found, yet 4 

 genera constitute 91 per cent of the total number of coral heads, thus: Porites 

 38 per cent, Seriatopora 25 per cent, Acropora 18 per cent, and Pocillopora 

 10 per cent. 



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800 1.000 1,200 



DISTANCE IN FEET FROM SHORE 



p IC 7.— Illustrating table J, showing number of kinds of coral at each- station on 

 Line No. I across the southeast reef-flat of Maer Island. 



Figure 6 gives a graphic representation of the total number of coral 

 heads on each 50-foot square at intervals of about 200 feet over the reef-flat. 

 The increase is quite regular from about 400 feet fro m shore, to 1,400 feet, 



Following references refer to table on opposite page: 



'In photographs of Maer Island corals at the end of this paper, plates 12-19. 

 ' s The various forms of nodular or massive Porites allied to Porites murrayensis could not be specifically dis- 

 tinguished one from another excepting after more detailed study than could be given in this inspection of the 

 living corals, and are therefore recorded as a single "species." This applies also to several of Acropora and Fama. 

 Indeed, the specific identifications being made upon living forms must not be taken too literally, for it is often 

 impossible to detect differences between clearly separated species until their skeletons are studied in detail. 1 hus 

 I record only 39 species from Line No. J, whereas in collections made along this line, and within 200 feet on 

 each side of it, Vaughan records 62 species. . 



The square 1,725 to 1,775 feet from shore is on the crest of the Lithothamnion ridge about 4 to 6 inches 

 above low-tide level of spring tides. The corals here are all small, stunted stocks clinging to the shallow crevices 

 in the breaker-washed tide-pools. When branched, the branches are thick, short, and most of them bend inward 

 toward the shore. r - c , 



The inner wash of the breakers makes a fairly strong current in the square 1,620 to 1,670 teet trom shore 

 and many of the corals are broken, but in this region the coral life is most varied in species, there being 26 kinds ot 

 corals as opposed to 18 in the region where the coral heads are most abundant. 



The 1,400 to 1,450 foot square is in relatively calm water about 200 feet inward from the innermost surge 

 of the breakers, and it is here the coral heads attain their acme of development, although there are more species 

 or corals about 1,600 feet from shore where the wash of the breakers is strong. 



The relative scarcity of most of the species of corals upon the square 1,000 to 1,050 teet from the shore ,s 

 due to the great development of large stocks of Seriatopora hystrix, for this coral alone covers about 40 per cent ot 

 the area of the square, and constitutes 70 per cent of the total number of coral heads in this region. 



In the square 1,200 to 1,250 feet from shore the Seriatopora is even more numerous but the stocks are gener- 

 ally small and broken by waves and do not cover more than 20 per cent of the area of the square. 



