Table 4.4 —RADIOACTIVITY OF THE SEVEN MOST COMMON ALGAE BY ISLAND, POSTSHOT* é : g A = Island Engebi . >” Bogallua Aomon Aomont Igurin 7 lgurint 5 Runit Ps Halimedat 1,700 240 2,500 2,500 150 4 22 13 120 Rigili PI Japtan : Rg . z Caulerpa Lyngbya 6,800 14,000 2,400 Cladephora Bryopsis 2,600 6,400 56 0.59 Janiat 5,300 6,200 2,500 3,900 9 700 Dictyota 10 0.33 820 36 16 69 240 0.25 * Measured in disintegrations per minute per gram (x 1000), wet sample. ¢ Coralline algae. t Dredged samples. 4.4 INVERTEBRATES In this section the pre- and the posttest sampling are reported separately since the collection and analyses of the data were made bydifferent individuals. 4.4.1 Pretest Methods of collection were the same as those for previous surveys; i.e., hand pries and gloves were used when necessarvto obtain specimens found while wading or swimming. The contents of the small dredge were examined on the stern of the M-boat from which the dredge was towed. Special attention was given to locating certain common animals intended to serve as a basis for comparing localities. These were, primarily, sponges, corals, sea urchins, sea cucumbers, ghost crabs, rock crabs, red-eved crabs, hermit crabs, snails, clams, and oysters. During the collection of these primary kinds, other invertebrates were also sought to obtain a collection that would be representative of the locality. Whereas most of the collecting was done on the lavoon side of the islands, approximately one-third was on the outer side, chiefly at Engebi, Runit, Japtan, and Igurin. Specimens from Piiraai were collected by the crew of M-boat 38. In the preparation of specimens for ashing, small specimens were ashed entirely, whereas large ones were dissected, and the tissues were ashed separately. In the case of intermediatesize specimens, hard parts, such as exoskeleton or shell, were separated from soft parts for ashing. Smaller samples of hard parts than of soft parts were used in order to equalize the quantity of ash on the plates. Animals from which tissues were dissected and ashed were sea cucumbers, sea urchins, large crabs, snails, and giant clams. ° Analysis of the data was based on sample counts of one or more tissues rather than on counts of the entire organism, as was done for certain treatments of the fish data. Attempts to compare species by areas on the basis of the ratios of activity of their tissues were thwarted by a lack of some sampies and bythe presence of many samples with only background counts, i.e., net sample counts of zero. Also the method of ranking was considered but was believed to be inadequate because of the great effect of surface contamination upon the average of a limited number of sample counts, as previously stated. oe