. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 312 RUDOLF S. SCHELTEMA the intensity of settlement from 3 to 42,623 organisms per hundred shell faces (= M2). The median intensity of settlement was between one thousand and ten thousand larvae per unit area; during sixteen of the twenty-five years the settle- ment intensity fell within this range (Fig. 14). In Astcrias jorbcsi the intensity of settlement was more variable from year to year. Tims, during six of the twenty-five years of observation, the density of settle- ment per hundred shell faces was between 1 and 1
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 312 RUDOLF S. SCHELTEMA the intensity of settlement from 3 to 42,623 organisms per hundred shell faces (= M2). The median intensity of settlement was between one thousand and ten thousand larvae per unit area; during sixteen of the twenty-five years the settle- ment intensity fell within this range (Fig. 14). In Astcrias jorbcsi the intensity of settlement was more variable from year to year. Tims, during six of the twenty-five years of observation, the density of settle- ment per hundred shell faces was between 1 and 10 organisms; during six other 10 1010 h- 10° 10° 10'1 - 10* -. 10 FIGURE 13. Relationship between frequency of larval dispersal (d) and population size (tv). The horizontal axis shows population size, and the vertical axis frequency of dispersal. In this example a value of X 10~3 is assumed for the drift coefficient (/>rf). This value is approximate for pa, in the North and Equatorial Atlantic Ocean. The curve shows the ex- pected frequency of larval dispersal (d) computed from various assumed population sizes when only one larva survives for each adult member of the parent population. Fluctuations in larval survival for most benthic species are expected to lie within the stippled region (vide Fig. 11; Thorson, 1946, page 439, Fig. 199; Coe, 1956; Loosanoff, 1964, 1966). years it fell between 10 and 100 organisms ; for nine years it was between 100 and 1000 organisms, and finally during two years it fell between 1000 and 10,000 organisms (Fig. 14). From these and other available data (Thorson, 1946; Coe, 1956) it appears that in most instances the fluctuation in successful settlement will lie within four and certainly five orders of magnitude. These data allow one to predict that the variation in the frequency of long-distance dispersal will probably also fall within similar limits (Fig. 13). In considering the frequency of long-distance dispersal it has been necessary
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
