TABLE 1: Number observed and frequency of kelp rafts by type

NATURE OF RAFT NUMBER OBSERVED FREQUENCY
Macrocystis 81 64.3%
Macrocystis pyrifera 51 40.5
Macrocystis spp. (incl. pyrifera, integrifolia, angustifolia) 30 23.8
Pelagophycus 27 21.4
Pelagophycus porra 20 15.9
Pelagophycus giganteus 2 1.6
Nereocystis luetkeana 2 1.6
Egregia sp. 10 7.9
Laminaria sp. 2 1.6
Sargassum sp. 1 0.8
Phyllospadix sp. 1 0.8
driftwood (logs, man-made objects, etc.) 7 5.6
miscellaneous (bottles, other organisms, etc.) 11 8.7

TABLE 2: Frequency of occurrence of major taxonomic groups on rafts (n = 126 rafts)

FREQUENCY TAXONOMIC GROUP (Occurences) FREQUENCY TAXONOMIC GROUP
78.6 ARTHROPODA (99) ECHINODERMATA (con't)
50.8 Amphipoda (64) 11.1 Echinoidea (14)
41.3 Decapoda (52) 5.6 Asteroidea (7)
38.9 Cirripedia (49) 58.7 COELENTERATA (74)
39.7 Isopoda (14) 51.6 Hydrozoa (65)
65.9 MOLLUSCA (83) 15.9 Anthozoa (20)
58.7 Gastropoda (74) 33.3 PORIFERA (42)
32.5 Bivalvia (41) 16.7 TUNICATA (21)
1.6 Cephalopoda (2) 8.7 PLATYHELMINTHES (11)
69.1 BRYOZOA (87) 3.2 NEMERTEA (4)
56.4 ANNELIDA (71) 5.6 SIPUNCULOIDEA (7)
52.4 ECHINODERMATA (66) 1.6 PYCNOGONIDA (2)
50.0 Ophiuroidea (63) 0.8 CTENOPHORA (1)
11.9 Holothuroidea (15) 7.9 VERTEBRATA (10)

TABLE 3: Marine invertebrate species with limited dispersal capability observed on kelp rafts with frequency of occurrence (N). Reproductive strategy and geographic range based largely on Morris et al. 1980.

SPECIES REPRODUCTIVE STRATEGY GEOGRAPHIC RANGE
N
porifera asexual or short-lived larvae various
42
Epiactis prolifera broods to crawl-away benthic stage Alaska to southern California
2
Balanophyllia elegans broods to benthic planula Oregon to southern California
2
Corynactis californica asexual Sonoma County to San Diego
2
Caprella californica brooder central and southern California
18
Pycnogonum stearnsi brooder British Columbia to central California
2
Phycolimnoria algarum brooder Oregon to Baja California
3
Crepidula spp. brooder various
6
Octopus bimaculatus brooder, short-duration larvae Santa Barbara to Baja California
2
Haliotis fulgens short-duration larvae Pt. Conception to Baja California
Leptasterias hexactis brooder Washington to Santa Catalina Island
1
Henricia leviuscula brooder Alaska to Baja California
1
Linckia columbiae autotomizes southern and Baja California, Columbia, Galapagos Islands
1
Amphipholis squamata brooder locally patchy, near world-wide
2
Ophioplocus esmarki brooder Tomales Bay to San Diego
1
Amphiodia occidentalis may brood Alaska to San Diego
3
Aplidium californicum brooder British Columbia to La Paz, Mexico
1

TABLE 4: Comparison of potential kelp raft vehicles including geographic distribution, depth distribution, substrate preference and holdfast morphology (based largely on Abbott and Hollenberg 1976)

Characteristic Macrocystis pyrifera Macrocystis integrifolia Pelagophycus porra "Pelagophycus giganteus" Nereocystis leutkeana
Geographic Distribution Alaska to Bahia Magdalena, Baja California; South America; New Zealand; Tasmania; Subantarctic islands British Columbia to Central California; South America Point Conception to Isla San Benito, Baja California Santa Catalina Island (endemic species?) Aleutian Islands to San Luis Obispo County
Depth Distribution 6 - 20 meters or more lower intertidal to shallow subtidal 30 - 90 meters 10 - 17 meters
Substrate preference rocky substrate over most of range, coarse sandy bottom off Santa Barbara rocky substrate primarily rocky bottom, extending into unconsolidated substrate (sand or shell) sand, gravel and other unconsolidated substrate rocky substrate
Holdfast size and morphology to 1 meter or more conical in shape 10 - 20 cm flattened, rhizome-like with lateral hapterae 10 - 40 cm compact to 1 meter or more spreading to 40 cm compact, hemispherical
Return to the text of Dr., Bushing's paper on kelp rafting