Tegner&Dayton81 Se Urchin Pop Rec, And Mortality

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Mar. Ecol. Prog. Ser 5: 255-268, 1981

Red urchins, 18m1974-1977, n = 8 3 8

40r 1 1 1

Red urchins, 15m1974 - 1977, n = 74 3

40 r ,

Red urchins, 12m30,1974- 1977, n = 75 3

TEST DIAMETER (mm)

Fig. 3. Strongylocentrotus franciscanus. Size-frequency dis-tributions of red urchin test diameters sampled from

November 1974 through August 1977 at 18 m (A) , 15 m (B )

and 12 m (C )

Strongylocentrotus purpurat us population structures

were similar at all 3 study areas as well as between

years. The annual da ta for the 15m site are in Fig. 4,

the composite data for all sites in Fig. 5. There was no

evide nce of a bimodal size-frequenty distribution for

purple urchins.

Recruitment

Table 1 summarizes the Strongylocentrotus francis-

canus collections by size categories - first, on the basis

of all in dividuals collected a nd secondly, on the basis

of th ose less t han 90 mm avoid the bias resulting fromthe commercial sea urchin fishery. Intensive harvest-

ing of urchins larger th an 90 mm beg an at Point Loma

in 1976 and decreases were observed in th e proportion

Purple urchins, 15m

A

I I . I , . I I I I .

0 20 4 0 6 0 80 I0 0

TEST DIAMETER (mm)

Fig. 4. Strongylocentrotus purpuratus. Size-frequency dis-

tributions of purple urchin test diameters sampled at 15 m

during 1974 (A). 1975 (B), 1976 (C) and 1977 (D )

Purple urchins, 18m

1974- 1977, n = 583

Purp le urch~ns, 15m1974- 1977, n = 957

Purple urchins, 12m

1974 - 1977, n = 1438

1 1 , , , . . , , r .

0 M 40 60 80 I00 0 2 0 4 O M ) ( 1 O I M )

TEST DIAMETER (mm) TEST DIAMETER (mm1

159.5. Strongylocentrotus purpuratus. Size-frequency dis-

tributlons of purple urchin test diameters sampled from

November 1974 through August 1977 a t 18 m ( A ) , 15m (B )

and 1 2 m (C )

of large urchins at the 15 and 12 m sites after 1975. For

th e 3 years studied, recruitment of red sea urchins was

regular and substantial in magnitude. As S. francis-



T e g n e r a n d D a y t o n : P o p u l a t ~ o n y n a m i c s of s e a u r c h ~ n s 2 6 1

F ig . 6 . S t r o n g y l o c e n t ro t u s f r a n ci s c a n u s . T o p : C h a r a c t e r i s t ic d a m a g e t o t e s t s of r e d u r c h i n s b y s h e e p h e a d w r a s s e s S e m i c o s s y p h u s

p u l c h e r w h i c h g e n e r a l ly b r e a k a l a r g e , s y m m e t ri c a l h o l e in t h e o r a l s u r f a c e . B o t t o m : S p i n y l o b s t e r s P a n u l i r u s i n t e r r u p t u s m a y

b r e a k h o l e s i n t h e o r a l o r a b o r a l s u r f a c e s of t h e t e s t o r m a y s i m p l y r e m o v e t h e p e r i s to r n i al m e m b r a n e

urchin around the lower lateral margin with its head.

On several occasions apart from these trials we have

noticed sheep head with sea urchin spines imbedded in

their foreheads. Once dislodged, the urchin was turned

over and attacked in the region of the peristomial

membrane. The Aristotle's Lantern was removed andthe mouth opening enlarged to allow access to the

gonads. The approximately symmetrical circular inci-

sion (Fig. 6) removi ng most of th e oral surface of th e

test is very characteristic of she eph ead predation . The

second mo de of attack was only observed once. A large

male sheephead grabbed an approximately 60 mm S.

franciscanus by the dorsal spines and bash ed it against

a rock until the test was shattered.

As discussed previously, juvenlle red and p urpleurchins seek shelte r under the spin e canopies of adult

red urchins (Te gner and Dayton, 1977). When the

observer removes the adults, a n action mimicking th e



Mar. Ecol. Prog. Ser. 5: 255-268. 1981

Localized ma ss mortality of red sea urchin, Strongyl ocen-

trotus franciscanus, near Santa Cruz, California. Fish.

Bull., U.S. 75. 645-648

Quast, J. C. (1968). Fish faun a of t he rocky insho re zone . In:

North, W J , Hubbs, C. L. (e d.) Utilization of kelp-bed

resources in southern California. Calif. Dept. Fish andGame, Fish. Bull. 139: 35-55

Rosenthal, R. J., Chess, J. R. (1972).A predator-prey relation-

ship bet ween the leather star. Dermasterias imbncata, and

the purpl e s ea urchin, Strongylocentrotus purpuratus.

Fish. Bull. U.S. 70: 205-216

Schroeter, S. C. (1978). Experimental studies of competition

as a factor affecting the distribution and abundance of

purple sea urchins, Strongylocentrotus purpuratus (Stimp-

son). Ph. D. thesis, University of Cal ifornia , Sant a Barbara

Strathman, R. G. (1978). Length of pelagi c peri od in

echinoderms with feeding larvae from the northeast

Pacific. J. exp. ma r Biol. Ecol. 34: 23-27

Taylor, L. R. (1972).A revision of the shar k family Heterodon-

tldae (Heterodontiforrnes, Selachii). Ph. D. thesis, Univer-

sity of Cal ifornia, Sa n Diego

Tegner, M J (1980).Multispecies considerations of resource

manageme nt in southern California kelp beds. Can . Tech.

Rep. Fish. Aquat Sci. 954: 125-143

Tegner, M J. , Dayton, P K . (1977). Sea urchin recruitmentpatter ns and implications of commercial fishi ng. Science .

Wash., D. C. 196: 324-326

Turner, C. H. , Ebert, E. E., Given, R. R. (196 8). The marine

enviro nment offshore from Point Loma, San Diego County .

Calif. Dep. Fish Game , Fish Bull. 140: 1-85

Wilson, K. C., Haaker, P. L., Hanan, D. A. (1977). Kelp restora-

tion in souther n California In: Krauss, R . W. ( ed.) The

marine p lant biomass of the Paciflc northwest coast, Ore-

gon State University Press, Corvallis, pp. 183-202

Winget, R. R. (1968). Trophic relationships and metabolic

energy bu dget of the Ca l~for nia piny lobster, Panullrus

interruptus (Randall). Ms. thesis, San Diego State Univer-

sity, San Diego

This paper was present ed by Dr N. D. Holland; it was accepted for printing on May 18, 1981

Tegner&Dayton81 Se Urchin Pop Rec, And Mortality

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