. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 20 g> 00 V O borealis L hexactis C digitalis N scutum C pelta Mar Vista 6 16 32 048 6 I6O 32O 6 SO I6O O 8 16. O borealis L hex act is C digitalis N scutum C pelta 20- 10- 00 -10- Cattle Pt 0 IOO'2O6 6~ 4 8 O 2O 4O Seppmgs Is 6 20'40 6 ' 4 e 0 borealis L hexactis N scutum 0 borealis L- hexactis Population Density (Individuals m ) FIGURE 2. Vertical distributions ofOnchidella borealis. Leptasterias hexactis. and associated limpets at four intertidal sites. Seppings Island is in Barkley Sound, British Columbia. All other si
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 20 g> 00 V O borealis L hexactis C digitalis N scutum C pelta Mar Vista 6 16 32 048 6 I6O 32O 6 SO I6O O 8 16. O borealis L hex act is C digitalis N scutum C pelta 20- 10- 00 -10- Cattle Pt 0 IOO'2O6 6~ 4 8 O 2O 4O Seppmgs Is 6 20'40 6 ' 4 e 0 borealis L hexactis N scutum 0 borealis L- hexactis Population Density (Individuals m ) FIGURE 2. Vertical distributions ofOnchidella borealis. Leptasterias hexactis. and associated limpets at four intertidal sites. Seppings Island is in Barkley Sound, British Columbia. All other sites are on the west side of San Juan Island, Washington state. the more exposed site, only one L. hexactis was found, next to a holdfast. An average of O. borealis (range: 13-64; n = 8) occurred in each holdfast. At the less exposed site, which was 200 m from the other site, higher densities of L. hexactis were found. Leptasterias hexactis in holdfasts were significantly smaller (mean = mm; n = 9) than individuals occurring in cracks (mean = mm; n = 12; P < , Mann- Whitney U-Statistic: Sokal and Rohlf, 1981). At the less exposed site, O. borealis were found primarily in shallow cracks above the level of the L. hexactis. Only one holdfast contained any O. borealis. The two species were never found within the same holdfast at either site. Limpets, which occurred abundantly at all sites, showed a characteristic zonation pattern (Fig. 2). Notoacmaea scutum occupies virtually the identical zone as O. bore- alis. The lower limit of Collisella pelta is slightly higher than that of 0. borealis and N. 'm, though the upper limit is at approximately the same level. Collisella digitalis ps the other species slightly, but peaks in its distribution much higher than O. hexactis, or any of the other limpets. These distributions suggest that all of the mollusc species except possibly C. digitalis should be available to L. hexactis as food. Freda invertebrates occurring in
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
