POPULATION DYNAHICS OF TEGULA A..l\J"D CALLIOSTOMA IN CAPJviEL BAY, HITH SPECIAL REFERE.N"CE TO KELP HARVESTING
A thesis submitted to the faculty of San Francisco State University in partial fulfillment of the req~irements for the degree Master of Arts, Biology
by
DOUGLAS EDWARD HUNT
San Francisco, California
June, 1977 ABSTRAC'l'
POPULATION Dx'NAMICS OF TEGULA Al\ID CALLIOSTOHA IN CARr1EL BAY, WITH SPECIAL REFERENCE TO KELP HARVESTING
Douglas Edward Hunt San Francisco State University 1977
A population study on six species of trochid gastropods living on Hacrocvstis is considered, with special reference to the effects of kelp harvesting. The study was conducted over a one year period subtidally in Carmel Bay. Vertical distribution on Macrocvstis and benthic abundances were determined for each of the six species. Size class distri- bution, feeding behavior, and predation are also discussed.
Tegula pulliqo was the most abundant species throughout
the year, followed by montereyi and Calliostoma liqatum.
SeaSonal variation in abundance occurred for all species, with minimums ~n May and maximums in January. This variation
is the result of disturbance by storms, and food availability.
The ge;.""1US was found to be herbivorous, feeding most
commonly on fy1acrocystis. Calliostoma was observed feeding
on colonial tunicates and hydroids.
Kelp harvesting caused a subsequent long term change in
distribution and abundance of T. monterey:i on t·1acrocvstis .. ACI I would like to thank my Committee members for their assistance and comments on my th s. Dr 1 s Thomas Kauffman and Edward DeMartini also contributed more than just their time, and I have profited greatly from their assistance. Thanks are also in order to Scott Kimura, my diving partner, and all of the divers at Moss Landing Harine Laboratory who as sted me. James Houk and Kim McCleneghan of the California Department of Fish and Game were also very helpful du:r:ing the course of my field research. Only my '.·rife Christine kno•..Ts how much I appreciate her constant encouragement a~d sacri ce during the months of T-•orkw on... -4-hl.L s- ~~.L,l-'1-- t....U.U':l_' ~ This research was funded by the University of California Sea Grant College Project R/CZ-21 under the direction of the late Dr. T.W. Tho;npson. iv TABLE OF CONTENTS Abstract iii Acknowledgements iv Introduction .. 6 Materials and f.'lethods 9 Results 14 Discussion 23 Conclusions 40 Literature Cited 42 Figures 45 Tables 70 v INTRODUCTION The giant kelp, r'lacrocystis pyrifera ( Linnaeus) C.A. Agardh, provides a substrate for the development of a unique faunal association (Andrews, 1945; Jones, 1971; Leighton, 1966; North and Hubbs, 1968). Among the fauna utilizing the Macrocystis habitat along the central Califor nia coast are two genera of gastropods, Tegula and Calliostoma. Current research by the California Department of Fish and Game indicates the probability that these gastropods repre sent a basic link in the near shore marine food web by supplying a portion of the diet for at least one species of fish, Hexagrammos decaqrammus (Pallas, 1810), and the sea otter, ~ra _;lutris Linnaeus 1 {James Houk, personal cornmunication ~ Vandervere. 1969). fvlacrocystis also provides the basis for a multi million dollar kelp harvesting industry (North and Hubbs,· 1968). Recently this industry has shown an interest in large seal~ harvesting of Macrocystis in central California.. Miller arid Geibel ( 1973) suggest that unique differences between southern and central California kelpbed communities precludes direc·t comparison of the extensive studies of North and Hubbs ( 1968) 1 Clendenning and \·ling { 1971) 1 Leighton { 1966), and others. Potential changes in environmental conditions prompted the California Department of Fish and Ga11e to initiate 6 7 studies on the effects of harvesting in the Monterey Bay area in 1970. One study by Hiller and Geibel {1973) reports that removal of the canopy at critical times of .the year can result in the loss of all plants in the harvested area. This observed loss Macrocystis also caused concurrent changes in the populations of Tegula and Calliostoma. The ecology of the genus Tegula, except for the intertidal species Tegula funebralis A. Adams, 1855, is relatively unknown. The three subtidal members of this genus occurring in central California are T. brunnea, T. pulligo, and T. mon·terevi. Jl.. short term qu.a.."'lti tati ve study by Lowry, et al. (1974) on se three species indicated a spatial partitioning of available !Vlacrocystis habitat. These results differed significa;.tly from the primarily descriptive Horks of Andrews, 1945; McLea"'l, 1962; Faro, 1970; and Hinter, 1971. The latter authors noted substrate preferences rather than quantifying partitioning of available resources. Recently Perron (1975) examined the feeding behavior of three subtidal species of Calliostoma: c. ligatum, c. annul a tum, and • ca.1aliculaturn. He found them to be predators of sessile animals displaying some degree of prey specificity. Personal lab and field observations indicate an a'pparent food preference among two species. C. liqatum feeds on the compound ascidian, Archidistoma molle Ritter, 1900, while C. annulatum feeds on several hydroids, including Abietinaria spp. Thus, availability of preferred prey may 8 spatially segregate these species. This work examines the environmental effects of harvesting on the populations of Tegula and Calliostoma. A one year population study of Tequla and Calliostoma considered the following: (1) Does spatial partitioning of the J:.lacrocystis habitat by Tegula and Calliostoma occur in Carmel Bay? (2) Are the size distributions, numerical abundances, and spatial segregation of these gastropods seasonally variable? ( 3) What are the effects of predation and kelp harvesting on the numerical abundances of Tegula and Calliostoma? NATERIALS AND METHODS Sampling was conducted on a monthly basis from r.tarch 1, 1975- through May 25, 1976. A kelpbed in a semi protected portion of Carmel Bay (36"33/N: 121° 57'w) approxi mirtely 0. 8 km off Carmel Beach, Carmel, California (Figure 1) served as the primary researCJ.~ area. The substrate ,.,i thin this area was primarily rock interspersed with sand and cobble, and provided a11. excellen-t habitat for Nacrocys·tis. The research area was selected on the basis of three factors: ( 1) general accessibility, ( 2} integration \vi th an existing California Fish at""'"ld Game study on kelp harvesting, and (3) experimental harvesting study for the past three years by Kelco (a kelp harvesting company from the San Diego area). Depths within the study area ranged from 13-18 meters, with a mean of 15 meters, ma1cing SCUBA an effective sampling tool. Over 123 hours of bottom time was compiled during the cour~.e of t..'h.e study.. Transportation to and from the study site was accomplished using Royak paddle-boards. In addition, the California Department of ·Fish and Game occasionally provided the use of the research vessel, Ophiodon. The study area consisted of four 60 meter diameter edrcles. Within each circle 20-25 randomly placed benthic stations were located on a planer coordinate grid system (Figure 2}. The California Department of Fish and Game 9 10 devised the above technique. Preliminary analysis indicated its effectiveness for use in study areas A and B. An eyebolt secured to the substrate with an attached surface buoy marked the center of each area. Station markers consisted of a subtidal buoy attached to a line approximately one meter above the substrate, or by a concrete nail driven into the rock with ! a flourescent yellow streamer attached. The latter technique subsequently replaced the former, as the subtidal buoys frequently bec~~e fouled in kelp plants or drift algae during periods of heavy surge a..'t1d were lost. The fvlacrocystis plant nearest each station marker designated a sample site. In Areas A and B stations were located by a compass bearing and distance coordinate much in the way that a 11 follow the dots 11 drawing is conceived. This method allo'\ved the diver to start from a..'l.y station, and mvim by compass heading to the next consecutive station. In Areas C a..'l.d D, an alternate method proved more efficient and easier to sample.. Two random numbers chosen between zero and 360 served as compass headings from the center poin·t of each. circle. A thirty meter line set follow- ing this predetermined compass heading allowed all kelp plants that occurred one meter or less on either side of the ~ine to be recorded and tagged with flourescent surveyor's tape. Tt~is method enabled a sufficient number of permanent stations to be rapidly tagged and required a minimum of maintenance. 11 No significant difference appeared between the two techniques when comparing the mean number of snails per plant using a two-tailed nonparametric r.lann~v7hi tney U test (Sakal and Rohlf, 1969) U20, 163: u 20 , 16= 179~ P>.os. Total snail densities in all study areas Here therefore inter- comparable by nonparametric tests. Areas A and B were controls, and Areas C and D served as experimental harvest areas.. Area A was sampled at four month intervals beginning in April 1975, to determine if any substantial population changes occurred seasonally. Ivlonthly sampling in Area B for one year documented short term variations the populations of Tequla and Calliostoma~ The two experimental areas were harvested once~ Area C by a kelp harvesting v~ssel in June 1975, and Area D by hand in October 1975. Before and after sampling, as well as one and six month follow-up surveys occurred in each area. Signi_fi- cant differences in spatial distributions for any of the '· species before and after the harvest were tested using non- parametric Hann-Hhitney U tests. I>1oni toring of the population size structure and vertical distribution of the six species of gastropods on Macrocvstis utilized a vertical line transect, divided into ti'teter intervals similar to techniques developed by LoHry, .E2!:. al. (1974). tvithout removal, each individual gastropod found within a given meter of plant thallus (bottom to surface canopy) was identified and recorded. This method 12 allowed a relatively undisturbed population to be studied 2 over the year. Circular 2m quadrats sampled the benthic occurrence of Tegula and Calliostoma around each plant hold- fast, as well as several other potential competitive species of benthic gastropods, including Homalopoma spp., Mitra idae Melville, 1893, Ocenebra spp., Pseudomelatoma torosa (Carpenter, 1865) gibberosa, (Dillwyn, 1817) and Ceratostoma foliatum (Gmelin, 1791). Different methods were used to obtain s~~ples for determining size class distributions of Tegula and Calliostoma on Macrocystis a...'ld on the substrate.. On .fvlacrocystis it was done by placement of the vertical transect line and collection of all snails found within each meter. Benthic snails were 2 collected from random 2m quadrats. All collecting took place a Hay from perma.."'lent stations.. The greatest basal diameter of each individual shell vras later measured in the laboratory with Vernier calipers.. Only • pulligo and T. montE:reyi occurred in sufficient quantities to indicate defined distribution patterns. Recolonization by snails of Macrocvstis plants stripped of gastropods was also monitored. A tagging experiment documented the mobility of gastropods. Thirty-five T. Eulligo and 34 T. monterevi taken t.rom labeled plan·ts \-lere painted with epoxy paint number codes either onboard a boa·t or underwater, depending on surge conditions. All labeled snails were then returned to the sites of collection on their respective plants, or near 13 their holdfasts. Other snails collected from the substrate near plant holdfasts were tagged and re·turned near the same holdfast. Observation periods occurred at 1 hour~ 24 hours, and 1 month intervals. A large number of independent field observations resulted from 123 hours of bottom time. These observations included notes on the feeding behavior of Tequla and Calliostoma and predation ac-tivities on these snails by asteroids and fishes. A four mon·th study collected the fish predators of Teaula a.rJ.d Calliostoma. Seventy-four individuals representing 12 species of the numerically dominant midwater and benthic fishes were analyzed for gut contents. Initial procedure included. identification, measurement of total length, and sex determination. FolloHing excision, stomachs were fixed in 10% formalin for later analysis. Identifica tions of contents followed standard lab techniques using . low pmver magnification. Food items were quantified using the J:ndex of Relative Importance (N% + V%)F% IRI (Pinkas, Oliphant, and Iverson, 1971). RESULTS Population Structure and Vertical Distribution in Control Areas TEGULA pulligo (Gmelin, 1791) Throughout the course of the study, Tegula pulligo occurred on Nacrocystis most abundantly, and with the highest' frec~ency (Table 1). The yearly variation in the mean number of snails per plant + one standard error is presented in Figure 3. The mean n'l.mber of snails per plant for the year was 25~32 ~ 2.03. Teaula Eulligo ranged over all depths, but occurred most co~uonly from the bottom of the plant to 4 meters above the substrate at all months of the year. (Figures 4-15). Tequla pulligo was least common from a depth of 3-4 meters to the surface. Around the holdfasts of Jvlacrocvs·tis, T. pulliqo abundance throughout the year ranged 2 + . from 0 to 75 snails per 2m , with a mean of 2.47 - 0.99 snails • 2 per 2m • The sauple population of T. pulligo consisted of 55% females and 45% males. Females represent 67% of the snails greater than 25 mm. Determination of the sex of smaller snails (less than 15 mm) proved difficul·t, even with 100X magnification. Seventy-eight percent of the less than 15 mm size group appeared to be female, although many \.Jere undifferentiated. 14 15 Tne size frequency distribution of T. pulligo collected in January 1976 (Figure 16) shows size classes grea·ter than 17 mm occur primarily on I'-1acrocystis (Figure 17), while those snails less than 16 mm occur primarily on the bottom (Figure 18) associated with sand and gravel chan~ nels. TEGULA monterevi {Kiener, 1850) The second most abundant snail found on f'.lacrocystis in the control area, T. montereyi had a mean density for the year of 9.82 ± .42 snails per plant. The yearly variation in mean number of snails per plaDt is presented in Fiy~re 3. This species occurred more commonly in experimental Area C, which is 1 to 4 meters deeper than either control area and has less benthic relief. These snails commonly occupy th,2 stipes near the su::::-face, and the kelp canopy (Figures 4-15) where large individuals ( 25-28 mrn) are common during periods of calm seas. The benthic distribu-tion of this species, while less variable tha~ T. pulliqo, has a mean for the year 2 of 0.91 ± 0.16 snails per 2m • Females represented 60% of the total population of T. montere:d:_, ~1hereas in the size class greater than .25 mm females represented 67%. The size frequency distribution of T. rnontereyi collected in January 1976 (Figure 19) indicates a distribu tion pattern similar to that observed for T. pulliqo; 16 small individuals occur on the benthos and larger snails occupy Macrocystis. TEGULA brunnea (Philippi, 1848) This species was observed to be the least common of all six gastropod species and never exceeded one individual per plant during the course of the year in control Area B. In control Area A, which is 4 to 6 meters shallower, T. brunnea occurred more commonly. This species rarely occurs on the-bottom. It appeared in only three of the two hundred 2 2m bottom ~Jadrats sampled. CALLIOST01'11A liqatum (Gould, 1849) c. ligatum, the most abundant species of the genus Calliostoma, is third in overall abundance. Figure 20 represents the yearly variation in mea~ number of snails per pl&~t. The yearly mean benthic density of C. ligatum was· 2 0.43 ± 0.27 snails per 2m • In contrast with the genus Tequla, the samples of C. ligatum were predominantly male (Table 2). The size frequency data for this species is presented in Figure 21. C. liqatum occurred most commonly at depths of 8 to 15 meters .. CALLIOSTO~ffi canaliculatum (Lightfoot, 1786) This species was the second most abundant member of the genus Calliostoma, and the fourth most common species overall. Observed most often from 5 to 10 meter depths 17 (Table 3), C. canaliculatum never occurred in the kelp canopye The yearly variation in the mean number of snails per plant is presented in Figure 22. C. canaliculatum occurred in 11.2% of the quadrats sampled in control Area B, but never 2 appeared in any of the 2m quadrats in control Area A. Generalizations about the sex ratio of this species could not be made due to an insufficient number of specimens. The size frequency distribution for C. canaliculatum is presented in Figure 21. CALLIOSTOfvlA annulatum (Lightfoot, 1786) C. annula~um was fifth in overall abundance and the least common member of the genus. The yearly variation in the mean number of snails per plant is presented in Figure 23. This species occurred in less than 2% of the 2 2m bottom quadrats- c. annulatum occurred most commonly on r~1acrocystis at depths of 5 to 8 meters (Table 3). An ins~fficient s~ople size made estimates of the sex ratio of this species impossible. The size frequency dis·tribution of C. aDnulatum is presented in Figure 21. Effects of Kelp Harvesting in Experimental Areas The mechanized harvesting of Hacrocystis which occurred in experimental Area C during June 1975 signifi- cantly altered the population structure of T. pulligo and T. montere:d:. Snails found on Macrocystis initially 18 decreased 32%. No significant change could be detected in the four less common species (i•lann-Hhi tney U test, all P>.OS) Table 4. Table 5 presents the before and after harvest abundances of T. pulligo and T. !,_TlOntereyi$ Significant changes occurred in the distributions T. pulligo and T. monterevi following the harvest (Table 6). Ho\.,ever, control Area B exhibited no change during the same period of time (Table 7). Hand harvesting in September 1975 in experimental Area D produced different results. Before and er harvest abundances of T. pulligo and T. monterevi in Area D (Table 8) owed ~~ increase 1n the abundance of these snails. Large numbers of individuals of both species occurred on upper plant thalli following kelp harvesting. The observed distributional changes of T. pulligo and T. montereyi following the harvest were tested against before harvest data within the same area, and data for unmanipulated coritrol Area B (Table 9). No significant change occurred ·in the distribution of any of the 4 less common species within Area D~ Nor '1.-Tas there a significant change in species distribution in control Area B during the same period (Tables 4 and 7). Tagging Study on T. pulligo and T. monterevi - - - ~ One hour observations on the 35 tagged T. pulligo shm·Ted that six of the animals had moved as much as 2.1 m up the stipes of the f:lacrocystis plant. 'l'wenty-four 19 T. Eulliqo remained Hithin the same meter interval. Tvo animals had migrated into the next lm.,rer meter interval, and three of the tagged animals could no·t be found on the stipes the plant. Further observation near the base of the plant revealed that one T. pulligo had apparently fallen off. This snail was moving rapidly up the holdfast of the plant } onto the stipes. The remaining two snails could not be located. Twenty-four hour observatioqs on the tagged T. pulliqo showed that 14 individuals occupied the same plant, 9 were shallower, 1 deeper, and 4 at the same depth. A search of the immediate vicinity revealed 2 additional tag ged snails on nearby plants. One month observations showed that two snails had moved to nearby plants. Seven occurred on the s~~e plant and the rest could not be located. The recovery ra·te after one month in the field was 25.7%. One hour observations on the 34 tagged T. montereyi showed 21 had remained in the same meter interval. Ten had moved into the next higher meter on the plant, and four could not found. None had emigrated deeper on the stipes. Twenty-four hour observations shoHed that a large montereyi (number 11, 26 mm basal diameter) had climbed 11. 6 meters in 24 hours. Seven other T. monterevi 'Here found at various intervals (6 occurred shallower, 1 deeper) on the plant with a maximum distance covered of 5. 3 meters. 20 Other ~· montereyi could not be located on the substrate. but three were located on nearby Hacrocystis pla;1ts. One month folloH-up observations provided a 17.6% recovery rate of tagged T~ monterevi. One snail had moved ten meters up the plant, t\vo others had each moved seven meters shallower, and three had moved up one meter. No other tagged snails were found. Size Class Distribution and Recolonization of l\1acrocystis Figures 24 and 25 represent size class distributions of T. £Ulligo and T. montereyi. Size class distributions of the other four species could not be made due to insufficient sample size. Initial recolonization of Macrocystis by Te~la and . Calliostoma occurred within 24 hours of the removal of all gastropods. Recruitment apparently originates from the substrate, as no snails were observed to colonize from the adjacent canopy. Initial colonizers generally represented indfviduals smaller than the original inhabitants. The mean number of snails per plant during June 1975 (12 stripped plants) was 40.0 ± 9. 67. One month la·ter the mea..'1 number of snails per plant was 20.60 +- 4.33. ""Predation on Tegula and Calliostoma Of the 12 species of fish exarnined, 4 were found to feed upon 'l'egula and/or Calliostoma: 'I'he lingcod (Qehiodon elonqatus) Girard, 1854; kelp greenling 21 (Hexagrammos decagrammus) (Pallas, 1810); striped seaperch (Embiotoca lateralis) Agassiz, 1854; and pile perch (Damalichthvs vacca) (Girard, 1855). Calliostoma spp. were not as important in the diet of lingcod as octopus. small fish, or crustaceans, but these fish apparently utilize this gastropod to some extent (Table 10). The kelp greenling represents an important 2 predator on Teaula. This common (density = 5.1/30m ) demersal carnivore utilizes Tegula as its second most common prey item in the Carmel area (Table 11). Fish densities were calculated from unpublished data provided by California Department of Fish and G~~e. No Embiotoca lateralis vlere collected, but observed feeding behavior indicated that striped seaperch feed on Tegula pulligo, especially those snails occurring on Macrocystis within one meter of the substrate. Both Te~~la pulligo and Calliostoma liqatum appeared in the stomach of one pile perch, Damalichthys vacca. These gastropods were second and third in relative importance for this individual (Table 12). Observations throughout the course of the study .,indicated active preda·tion by asteroids on Te~la and Calliostoma. Rycnopodia helianthoides (Brandt, 1835) was 2 the most common {4-7/30rn } asteroid predator of Tequla and 22 Calliostoma in the study area. On one occasion an individual sunstar attacked and fed on 11 T .. pulligo in a 35 minute period. In July 1975 a small ~ycnopodia (120 mm in diameter) was observed climbing 1.4 meters up the stipes of a r.'lacrocystis plant to feed on T. pulliqo. Orthasterias 2 koehleri (de Loriol, 1897) while less common (0.8/30m ) than other seastars, was observed to feed on T. montereyi· on one occasion. DISCUSSION Spatial Distribution of 'l'equla and Calliostoma Subtidal spatial segregation among central California members of the genus Teaula living on Macrocystis has been suggested by Lowry 4 et al. (1974) and Smith and Gordon (1948). At aepths of 6 to 9 meters near Hopkins Marine Station, LoHry, al ~ ( 1974) shm.;ed that in August Teaula ~lliao, Tequla montereyi and Tegula brunnea vertically segregate on Hacrocvstis .. My observations from Carmel Bay indicated that Tegsla montereyi frequently occurs near the surface and in the canopy of P.Iacrocvstis. This observation agrees with published data by Faro (1970) for the depth range of 5 to 21 meters at a site near Point Pinos, approximately 10 km nor-thwest of the Carmel study site. Another study near Hopkins Marine Station at depths of 10 to 12 meters (Hiller and Geibel, 1973} shm>Jed T. !!lontereyi to be the most abundant gastropod found in the canopy of Hacrocystis. Lowry, et al.(1974) found T. montereyi more commonly on the stipes of Macrocyst is, rather than in the canopy. At 1m area approximately 14 km south of my study area, IvicLean (1962) indicated that T. monterevi was common on Macrocystis, 23 24 however, vertical distribution of this species on Macrocystis was not determined. In control Area B, T. brunnea was very uncommon throughout the year on the substrate and on the stipes of fviacrocystis. In Area A, which is 4 to 6 meters shallower, T. brunnea was more abundant for the year. This observa·tion contrasts with LoHry, et al. (1974) -v1ho observed this species to be the most abundant gastropod within the Nacrocystis canopy~ while Faro {1970) and r.lcLean (1962) also indicate that T. brunnea commonly occurs on the substrate. Descriptions of the habi ta·t in each of the previously related papers, except IVIcLean, appear similar to my observations in Carmel Bay. Two notable· environmental variables include depth and surge factors. Lowry, al. { 1974} working in shallow water { 6 me·ters) observed T. brunnea to be the most common gastropod found in the canopy~ however, less than 2 km away, Miller and Geibel (1973) in a deeper, (10 to 12 meters) more exposed area, observed T. montereyi as the most common gastropod occupying the canopy. This v.1as also observed in Faro's deeper water study. r.r:"le observations of ·these authors, and the results of my 12 month deeper \vater ( 15 meters +) study, suggest ~that T. montereyi may be better adapted to climb greater distances up the thallus of f;lacrocystis in deeper, more exposed areas. In shallow, more protected areas, T. brunnea 25 may be numerically dominant in the canopy region, where it may not compete with the deeper vater species. The observed decrease in abundance of T. brunnea with depth also suggests a depth limit on this es at approximately 10 to 12 meters. Hhether this apparent limit is due to competition with o·ther gastropods for a preferr.ed food source, a physic limitation of T. brunnea, or some other intrinsic factor,· is unknown~ HO'.-lever, all three species of Tegula were observed in the fi a~d later in lab aquaria to preferen- tially on jured portions Macrocystis. montereyi both in the field a~d in the aquarium, was observed to be the most gastropod at upward movement on Macrocystis stipes and on the side of the aquarium. These observations suggest that T. brunnea and T. monterevi spatially segregate on Hacrocystis at fferent bottom depths. In shallow water where T. monterevi is less common, T. brunnea utilizes the canopy region of Nacrocystis. In deeper water where T. montereyi is more comrnon, this species will occur in the canopy t-lacrocvstis. Throughout the year T. pulliqo was the most abundant trochid sn , both on t-1acrocystis and the substra.t:.c. T. ;eulliqo most commonly occurs throughout the year between the holdfast and four meters above the substrate (Figures 15). In shallow water T. pulligo has also been shown to occur most commonly near the base of 26 ~4acrocystis (Lo\-rry, et al., 1974). Thus, T. pulliqomay be spatially segregated on Hacrocystis from T. montereyi at depths greater than 10 meters, and T. brunnea at depths less than 10 meters. I never observed habitat partitioning among the three species of Calliostoma living either on r1acrocystis or on the substrate of Carmel Bay. LoHry, et al. (1974) suggested that the differences in Calliostoma spp,; distri bution might be related to individual food preference of these predatory snails. Observations by Perron (1975) in w·ashington 1 indicat£.0. at c. annulatum feeds primarily on hydroids, while • liqatum fed on diatoms and detritus. In Carmel Bay I observed c. annulatum commonly feeding on the hydroid, Abietinaria, whereas c. ligatum often fed on the compound ascidi~1, Archidistoma molle. These variations in observed feeding patterns infer that the distributions of C. annulatum &"'1d C. ligatum may be related ·to preferred prey distributions rather than spatial partitioning of the same food source. Seasonal variations in abundances and distribution of 'l'eaula, and to a lesser extent Calliostoma, appear <>;;controlled primarily by physical disturbance rela·ted to storms. SCUBA observations folloHing storms revealed a substantial decrease in the number of snails found in the canopy and near the surface on t"lacrocystis plants. 27 Follovdng a storm in February 1976, benthic abundance for T. pulliqo ru1d T. montereYi increased from the previous month by 11% and 14% respectively. Bakus (1974) reported this type of perturbation of snail populations living on t:lacrocys·tis in southern California. Seasonal changes in food preference in molluscs, as shown by Himmelman and Carefoot {1975) may also contribute to these seasonal varia tions. Fa-vorable weather and relatively calm sea conditions prevailed throughout the summer, fall, and most of the winter of 1975 until February 1976. This resulted in an increased number of snails per plant for T .. pulligo and T. montereyi. Near the end of February and throughout Narch, April, adverse sea conditions caused a substw~tial decline 1n the mean number of snails per plant? primarily in the upper 5 meters. Swell and surge probably di~lodged these animals. 'fhe high abundance of gastropods occurring on Hacrocvstis from December through February may be somev.1hat skewed. The unseasonably mild weather experi enced during this period probably allo;,-1ed more snails to remain on the plants. During a "normal winter" the density of these gastropods on Macrocystis would be much lower .. Rosenthal, al .. (1974) reported a 46% decrease in the number of adult Hacrocystis in their study area during t.he months of December through February. This loss of food 28 source and principal habitat could cause a decline in the popula·tions of !· pullig£ 2nd T. montereyi during stormy winter and early spring mon·ths. The three species of Calliostoma also exhibit a pattern of summer - fall increase followed by winter - spring decrease in their r ative abundances on Nacrocystis. The initial decrease of c. liaatum and c. canaliculatum during November - December 1975 appears to be greater in magnitude than noted for either Tequla spp. or Calliostoma annulatum. This decrease may be due ·to variations in distribution of prey animals, Calliostoma may have a less tenacious grip tf1an Teaula, or it may be an artifact related to a 10% loss of f."lacrocystis which occurred in the control area during December 1975, and January 1976. One of these displaced plants contained a proportionally high number of C. ligatum. Calliostoma liqatum was the most common member of of the genus found on the substrate, an observation \·Ihich agrees with t..'"lose of Faro ( 19 70) , and McLean ( 19 62). In addition, this species commonly occurs near the base of J'.lacrocvstis (Table 3). rrhis species main·tains a close proximity with the substrate, a factor related to possible "'food preference or poor climbing ability. 29 Factors Contributing to Gastropod r-'ligration onto t>1acrocvstis Evidence indicates that there is a spatial segre- gation of adult and juvenile segments of the populations of T. pulliqo and T. montereyi. Histograms of those snails collec·ted from the substrate and on r~Iacrocystis clearly illustrates the size segregation (Figures 16-19). Those snails greater than 15 mm are consistently found on the stipes and blades of Nacrocystis. Juveniles, those smaller than 15 mm, occur primarily on the substrate associated with gravel channels. Paine (1969), observed that larval T. funebralis inhabit the high intertidal,.while the adults occur loHer in the intertidal.. He relates this segregation to different food preference and/or selective predation. Subtidally, juveni T. brunnea and !~ pulligo commonly occurred on the substrate, ·v.~hile adults were found on Laminaria dentiqera Setchell, ru~d Pterygophora californica Rurprecht, (NcLeili'!, 1962). LoHry, et al. (1974) noted that -- . . smaller individuals of Tegula and Calliostoma \vere found on low-lying benthic algae, whereas the adul·ts occurred on !'lacrocysti s. Subtidally, observations indica·te that the spatial segregation of adult and juvenile Tegula is related to differences in juvenile and adult food preference, inter- specific competition, and predation. Personal observations indicate that juvenile Tegula settle on the benthic substrate. 30 Later, after attaining 15 to 16 mm basal dimneter, most move onto Nacrocys·tis. This separation of the population may be due to enhanced growth of juveniles living in the absence of adultsp Paine (1969) observed that juvenile T. funebralis grew faster when segregated from adults. Size related differences in food preferences may enable the faster grO\-ith of small Tegula. Paine and Vadas ( 1969) found that algae exhibiting an ephemeral or annual growth form including diatoms and small red algae, had the highest caloric content. Diatoms and small annual red algae, Plocamium cartilagineum (Linnaeus) Dix. , ; 'Heeksia spp., and Schizymemia spp. r inhabiting the Carmel Bay substrate contribute to the observed die·t of juvenile rrequla. These high energy food sources may be partially responsible for the juvenile-adult segregation. Adult Te~Jla feed on I·,lacrocvstis, a perennial lo-.,., in caloric content (Paine and Vadas, 1969). and Vadas observed, however, that availability of a food source rather than absolute food value, was the criteria for determining the preferred food of the invertebrate herbivores tested. Macrocvstis is the most abundant and available food source utilized by adult Tegula. Interspecific competition for food by the more abundant snail, Homalopoma, may also be an environmental stimulus for the migration of Tequla onto f•1acrocystis. 31 These small detri·to-herbivores appear to represent a major competitor for food resources with juvenile Tequla. I observed small individuals of T. Eulliqo and T. montereyi commonly feeding on the same food source (drift algae, diatoms, and detritus) as Homalopoma. The relatively high abundance of this snail may be a source of pressure on the benthic "niche" occupied by small Tequla. Predation cru~ be a major population_ regulator in the intertidal zone. Paine (1969) showed that the presence of the predatory .sea star, Pisaster ochraceus (Brandt, 1835) represented a major factor in maintaining population stabili-ty of T. funebralis. Subtidal observations indicated similar predation by Pycnopodia helianthoides on Tequl~ and Calliostoma. This predation may also represent a stress on benthic habitation by large snails. The larger individuals would provide a greater caloric content and pres1,1mably be taken more often L~~l smaller individuals if both sizes wer~ in equal abundance. Certain predatory snails found in the study area ( Oceneb..E.£ spp. and Ceratostoma foliatum) may contribute to the movement of T. Eulliqo and T. mont:ereyi onto r>iacrocvstis. Alt:hough predation by molluscan predators was not actually observed, 11 drilled" Tegula shells were *J, found in the study area. It is not kno\m whether this drill- ing was the result of predation by gastropods, or by Octopus which were common in the area. 32 A further stimulus for migration of 'r. pulligo and T. monterevi onto rvlacrocystis may be the presence of several numerically abunda..Tlt demersal fish carnivores. In two of these fish, ·the kelp greenling, Hexagrammos decaqrammus, and the pile perch I. Damalichthys vacca. Tegula and. Calliostoma made up a major portion of the observed diet (Tables 11 and 12). Other food items present in the· stomachs of these sh were strictly benthic organisms. Pile perch have bes1 shown to heavily utilize benthic gastropods . (Limbaugh, 1955) 1 whil:!h suggests that these fish do not forage more than a meter off the bottom and probably feed on Tequla living on or near the substrate. A striped sea perch, Embiotoc lateralis, \vas observed approximately ~5 m off substrate feeding on /?equla inhabiting Hacrocystis~ Gnose (1971) also observed that E. lateralis fed on Tegula and Calliostoma in Oregon. These three fish predators probably take larger snails fourrd on the substrate and on the lower meter of Macrocystis stipes, but were never observed to feed on small (less than 14 mm) snails found on the bottom. The disruptive coloration on the periphery of the shell makes juvenile T. oulliqo almost impossible to observe # when found in gravel; however, they stand out against the dark bad::::ground of Macrocystis. The slate grey color of T. monterey-~ also makes them difficult to observe on the 33 substrate. 'I'he color pa-tterns of these juvenile snails may act as protection against benthic visual predators such as fish, but Hould have little effect ·on olfactory predators such as sea s·i:ars. It would seem advan·tageous for these small snails to remain on the substrate until their shell is overgrown \·lith diatoms, or the juvenile coloration pattern is lost. Premature migration onto Nacrocystis whould increase their Vlllnerabilit.y to fish predators in the exposed lower meter of plant thallus. Upi..,ard thgration a...id Size Class Distribution of Tegula pulliqo and Tequla montereyi The ze class distribution of T. pulligo on Macrocystis (Figure 24) illustrates the relatively large propor-tion of the 19 through 21 mm size ranges found within four meters of the substrate. Food preference may account for the high occurrence of T. pulligo on this portion of the plant. Sporophylls produced each year by t·1acrocystis concentrate in the lower 1-2 meters of the plant and may represent a high energy food source. Young, fast grm.,ring sporophylls have been shmm to be h.igh in pro·tein { ' 1971). Climbing ability may also be related to the deeper distribution of T. pulligo. T. pulligo appears to be more easily dislodged than the similar sized rr. montereyi. Hiller ( 1974) observed differen·t types and rates of locomo- 34 tion tenacity of adherence to a ate for three of the genus Thais. The abi y of a species to adhere to a given ate Has direc·t related to the habitat of the species. A exposed to heavy '"ave action in mid-intertidal apparently main- a better grip than its count in the less high intertidal.. Th may be a factor in restricting rrnve- ment some T. on Macrocystis. The distribution of size classes of T. montereyi on Nacrocvstis (Figure 25) illustrates a some\·rhat different pattern than tha'c for T ~ J2ulliqo. T. in the 24 - 25 mm ra.Dge are concentrated near the ( 5 meter canopy) , Hhile small individuals ( 21 and 23 mm) appear to be stributed over the entire range. T. monterevi moves up e stipes at a much faster rate than did T. nulliqo. displaced during the tagging. study, T. monterevi moved higher up the stipes than did T. in the sw~e length of time {up to 11 meters in 24 hours). Rate of movement may represent a significant factor spatially ing these two closely rela·ted species sting on the same food resource. An observation noted during the displacemen·t, *J tagging, and replacement study suggests that environmental perturbation may also contribute to habitat partitioning and upward migration in both species of Of the 63 35 animals observed one hour after tagging, 16 had migrated up the stipes, and only b.,ro had moved do-.m. This upward move- ment is greater than would be expected by random movement (Two-tailed Binomial test: P <.05). Light is another factor that may contribute to the distribution of Calliostoma living on l\1acrocystis, and has received only cursory attention. Keep (1935) reports on the positive phototaxis of C. annulatum in the kelp canopy near Monterey. Field observations did not indicate a P,Ositive phototaxic response for any of the gastropods under observation. A diurnal migra-tion pattern has never been demonstrated for a subtidal species of Tegula, however, Kosin (1964) found the intertidal gas·tropod T. funebralis to be negatively phototaxic. Th reaction appears commonly in intertidal invertebrates (Ricketts and Calvin, 1968), but may represent a desiccation or predation avoidance response. The Effects of :Kelp Harvesting on the Distribution of Tequla and Calliostoma on Nacrocystis Quast (1968) and Clendenning (1968) calculated that beJcween 11 and 25% of the canopy-inhabiting invertebrates in ~southern California would be lost during harvesting of Macrocystis. Clendenning based his calculations on simulated harvesting involving manual shaking disturbance of six kelp fronds. Animals that fell off were counted in 36 relation to those that remained attache¢!.. Animals most likely to remain on the fronds included molluscs, turbellar- ians, and nematodes. Miller and Geibel {1974), working in central California 1 concluded that their small-scale hand harvesting operation did not adequately assess the effects of mechanical harvesting. Hm-1ever, short term changes in the populations of canopy inhabiting invertebrates occurred subsequent to hand harvesting. The most striking change observed was the decrease in the. average size of Calliostoma canaliculab.1m and all three subtidal species of Tegula. Hy obser-vations indicate an initial 32% decrease of Teaula pulliqo and Te~la montereyi inhabiting t-1acrocvstis following the mechanized harvesting of experi- mental Area C in June 1975. The initial decrease was primarily observed for Tequla montereyi. Before the harvest T. montereyi was the most abundant gastropod observed, 1.3 snails per {Table 5). One month later they had undergone a reversal in abundance. Tegula pullig~ became the most common {1.2 snails per meter) gastropod on Macrocystis in Area C. In control Area B, no significant change occurred in the abundance or distribution of T. pulliqo or rr. montereyi during this period of time (£v1ann- \·lhi tney U test; P >. 05 1 Table 7). One month follm·ring the harvest the distribution of T. E.Ulliq~ and the other species 37 ,~as not significantly different from the,preharvest distri- but ion, hm.,rever, the distribution of T. monterevi 'Has significantly different (fvlann-l;·lhitney U test: P <.OS). After six months the distributional changes and abundance decrease initially observed for T. montereyi remained significantly different from before the harvest .. (fvlann-vJhitney U test; P <.OS, Table 6). Greater affinity of T .. montereyi for the upper regions of the kelp plan·t \.Jhere it experiences greater exposure to the effects of the cutter blades on the harvester is probably the reason for the long term alteration in the population structure. 'l'he California Department of Fish and Game observed three times as many T. montereyi found aboard the harvester as were T. pulliqo {unpublished data provided by James Houk, California Department of Fish and Game, ftlonterey, CA). In experimental Area D, the effects of harvesting on abundances ofT~. pulligo and T. montereyi were minimal. Significant distributional changes for both species up to one month later were noted (Table 9).. The snails were concentrated in the upper tvlO meters of depth feeding preferentially on cut blades and stipes. Data with respect ·to hand vs. machine harvesting is probably not directly comparable. l;·lhen Area C was harvested by the harvester, the kelp was cut and hauled aboard quite rapidly, thereby eliminating the extended escape time created \vhen the fronds 38 v.1ere cut by hand and to,,.red by a diver to a waiting boat and hauled ou-t of ·the kelp bed. 'l'his technique obviously allo,tled large numbers of snails that were on the cut fronds to drop off and move onto other t1acrocystis plants in the s~~e area, thereby accounting for the net increase 1n the observed populationsc This caused the distribution of snails in the ha.'l.d harvested area to be exactly opposite of the machine harvested area. The apparent short and long term fluctuations observed for T. pulligo and T. montereyi do not occur for the less common T. brunnea, or for any Calliostoma inhabit ing f,.1acrocvstis. This ',-las probably the result of the rare occurrence ofT .. brunnea and the distribution ofthe three species of {Table 3). The greatest percentage of Calliostoma exist 'Hell dm·m the plant where they are less effected by the action of the harvester or by hand cutti?gD The changes that took place in Carmel Bay, while not:minor, were not of the same order as the massive disruption of habitat observed by Rosenthal, al. (1974) off Del r-'lar, California. My results suggest that if harvest ing takes place more ·than once a year and if ·the loss of Macrocystis occurs on the scale observed in southern ;!# California, snail populations could be significantly altered over long periods of time. Data provided by CalifJrnia Department of Fish and Game after three harvests conducted 39 in Carmel Bay during the summer 1976, indicate that there was a steady decline in the number of T. montereyi taken aboard -J;:he harvesting vessel. \'lith the loss of larger T. montereyi from the canopy region, a significant portion of the effective breeding population may be eliminated in the Carmel Bay study area if harvesting is continued on a large scaleo CONCLUSIONS 1. Tegula pulliqo and Tegula montereyi spatially segregate on Macrocystis throughout the year. __,_Teaula__ pulligo, the most common member of the genus, occurs primarily near the bottom of the plant. T. montereyi occurs at aLii levels on the plant, but appears to favor the canopy region~ These snails probably occupy different levels of Nacrocystis as adults because of different morpho- logical adaptations for speed and tenacity, and prefer- red feeding zone~ Tegula brunnea rarely occurred deeper tha,."'"! 12 s, suggesting a depth limit of T. brunnea in the t1onterey Bay area. 2. The juvenile and adult segments of the population of T. pulliqo and T. montereyi are segregated with juveniles on the substrate a.TJ.d adults on r.lacrocystis plants. Light · colored cryptic juveniles are subject to extensive fish predation when against the dark background of r·'lacrocystis. Later in development, subadults move up the stipes to utilize a common food source and escape demersal predators. <93. Calliostoma liaatum commonly inhabit the basal area of Macrocystis, including the adjoining benthos and sub~ strate. However, C. canaliculatum and c. annulatum 40 41. primarily occur in the mid-depth range on Macrocvstis. Evidence indicates ·tha·t the distribution of this genera is related to the distribution of preferred prey for each species. 4. Seasonal variations in the distributions of Tequla and Calliostoma on Nacrocystis are related to disturbance caused by winter ruid spring storms. These storms cause snails to lose their grip on the stipes and fronds of r migration back onto r1acrocystis takes place due to observed ion by demersal fish and asteroids. 5. Kelp harvesting had a detrimental effect on the popula tion structure of Tequla monterevi in the mechanically harvested area. A decrease in. density \-Tas noted over a six month period as ,.,ere long term significan-t distr_i butional chru!ges. Therefore, the snails species j.nhabi ting the ca.rwpy of Macrocyst is would be· mos·t severly impacted by kelp harvesting. In shallow water this would probably be Tequla brunnea and in deeper water, montereyi. LITERATURE CITED Andrews, H.L., 1945. The kelp beds of the Nonterey region. Ecology. 26: 24-37. Bakus, G.J., 1974. Kelp beds, browsers and pollution. Stomatopod, 6, (2): 124-129. Clendenning, I<. A., 1968. Harvesting effects on canopy invertebrates a.."'ld on kelp plan·ts. Pages 219-222 in Utilization of Kelp Bed Resources in Southern California, Eds. W.J. North and c. Hubbs. c·alif~ Fish and Ga~e Fish Bull. 139. Faro, J .B., 1970. J.\. survey of subtidal sea otter habitat off Pain~ Pinos, California. M.Sq thesis, Humboldt State College, Aracta, Calif. pp 278. Frank, P.W., 1965a~ Growth of three species of Acmaea. Veliger, {3): 201. Frank, P.W., 1965b. Shell growth in a natural population of the turban snail, Tequla funebralis. Gro'lrrth, . 29: 395-403. Gnose, G.I., 1968. ecology of the striped perch (&nbiotoca lateralis) in Yaquina Bay, Oregon~ .r.·I.S. thesis, Oregon State University, Corvalis, Ore. pp 53. Jones, L.G., 1971. Small herbivorous invertebrates of the canopy and holdfast. Pages 343-366 in The Biology of Giant Kelp Beds (Macrocystis) in California, Ed. H .J. North. (Nova HedHigia 32 Suppl.). J .. Cramer, Lehre, Germany. Keep 1 J., 1935. West coast shells. (Revis by J~L. B~ily) Stanford University Press, 350 pp. Kosin, D.F., 1964. Light response of Tequla funebralis. Pages 46-69 in The Biology of Tequla funebralis, Eds. D. Abbott, L. Blinks, J. Phillips, and R. Stohler. Veliger ~: Suppl. 42 43 Leighton, D.L., 1966. Studies on food preference in algivorous invertebrates of Southern California kelp beds. Pacific Science, 20 104-113. Limbaugh, c., 1955. Fish life in the kelp beds and the effects of harvesting. University of California Inst. Marine·Resources. IMR Ref., (55-9): 1-158. Lov1ry, L., A. r'1cElroy, and J. Pearse 1 1974. The distribu tion of six species of gastropod molluscs in a ~ California kelp forest. Biol. Bull., 147: pp 386. NcLean, J .H., 1962. Sublittoral ecology of kelp beds of the open coast area near Carmel, California. Biol. Bull., 122: 95-114. Miller, D., and J. Geibel, 1973. Summary of blue rockfish and lingcod life historiesr A reef ecology study; and giant kelp 1 i"lacrocystis EYE if era 1 experiments in Nonterey Bay, California .. Calif. Fish·and Ga~e Fish Bull., 158, 137 pp. t>Iiller, S. L., 1974, Adaptive design of locomotion and foot form prosobranch gastropods. J. of Experimental l•1ar Biology Ecology, 14: 99-156. Minter, c.s. III., 1971. Sublittoral ecology of.kelp beds off Del Honte Beach, Monterey, Calif. f'-1. S. thesis, Naval Postgraduate School., Nonterey, Calif. 177 pp. North, H.J., 1971. The biology of giant kelp beds O'·"lacrocystis) in California (Beihefte Zur Nova Hedwigia; Heft 32). North, ~·l., and C. Hubbs, 1968. Utilization of kelp bed resources in Southern California. Calif. Fish and Gw~e Fish Bull. 139. Paine, R.T., 1969. ?~e Pisaster- Tegula interaction: prey patches, predator food preference 1 and intertidal community structure. Ecology, 50~ 950-961. Paine, R. , and R. Vadas, 1969. Calorific values of benthic· marine algae and their postulated relation to invertebrate food preference. r.1ar. Biol. : pp 79 ~ 44 Perron, F., 1975. Carnivorous Calliostoma from the north eastern Pacific. Veliger, 18 (1): pp 52. Pinkas, L., H.S. Oliphant, and I.L. Iversson, 1971. Food habits of albacore, bluefin tuna and bonito in California \-Taters. Calif. Fish and Game Fish Bull. 152:105 pp. Quast, J., 1968. The effects of kelp harvesting on the fishes of the kelp beds. Pages 143-148 in Utilization of Kelp Bed-Resources in Southern California, Eds. W.J .. North and C. Hubbs. Calif. Fish and Ga~e Fish Bull. 139. Ricke·tts, E.F._, a.:..d J~ Calvin, 1968. Beb.feen Pacific tides. Ed. by J .\L 'Hedgpeth. Stanford University Press, 4th Ed. , 614 pp. Rosenthal, R.H. Clarke, and P .. Dayton, 1974. Ecology and natural history of a stand of giant kelp, (Nacrocvstis pvrifera), off Del t-lar, California. Fishery Bull. 72: (3) pp 670. Smith, A.G., l\L Gordon Jr., 1948. The marine mollusks and bra.Dchiopods of Nonterey Bay, California and vicinity. Proc. Calif. Acad. Sci., Ser. 4, 26: 147-245~ Sakal, R.E. a...rd F.J. Rohlf, 1969. Introduction to bio statistics~ H.H. Freeman & Co. Press. 357 pp. Vandervere, J.E., 1969. Proceedings: Feeding behavior of the souG~ern sea otter (6th annual confer. on biol. sonar and diving mammals}. 1 Hing , B.L. and K.A. Clendenning, 1971. Kelp surfaces and associated invertebrates. Pages 319-339 in The Biology of Giant Kelp Beds {Nacrocystis} in Cali a, Ed., W.J. North. (Naval Hedwigia 32 Suppl). J. Cramer, Lehre, Germany. 45- FIGURE 1 PEBBLE BEACH .. .. PESCADERO POINT \)., ~;···~. . U,Rl'·1EL BAY STLIJJY AREA ~------ CARfvlEL BAY STUDY AQ.EA Nm VIciNITY 36 0 33 / N.;l21 0 57 , W. FIGURE 2 ··-:-~ /.. . MEA B AR.EA D CoNTROL flREAs A& B AND ExPER I rvlENTAL AREAs C & D · P(n~.rrs REPRESENT STATIONS LOCATED IN EACH STUDY MEA, fiGURE 3 Tegu/a pulligo ~-4) 40 Tegula n1ontereyi o--o ·y::,: ..)· +-c 30 -CJ r 0. 25 '(/) ·a 20 c (.{l ,.._ 15 0 =tf !X 10 5 o~.--~~~~--~~~~--~--~~~~--~~- Jan Feb Mar Apr May Jun Jul. Aug Sep Oct Nov Dec Months X No, oF. SNA I LSI PLANT ~ 1 S,E, IN CoNTROL AREA B THROUGHOUT THE· YEAR N=20 FoR EAcH MoNTH 48 FIGURE 4 T. montereyi J-----o----1 T. pulligo ~ en .-;:a rO-l r-l---t > 1--{}-l ~-----~ '- !j (i) ...... ,!; 7-1 '- 8· t-----0---i J--ti-----t ...... XNo. oF SNAILs/i"'t:TER ± 1 S.E. oN f'l-\cRocvsns_ IN CoNTRoL MEA B FOR THE f'bNTH OF JANUARY N=20 49 FIGURE 5 T. montere 1J ,o,;(H T. puJligo 21 .l-0-l !-l,t-4 3 ....~ . 41 !{}! ~--~ :\ ; >-=~ 71 .~Q-J ~ 8i l{}l r-~.--1 I 1~1 """ c 11J .c. +-'n i2l (1) 0 ·t--G----1· 1.0 2.0 3.0 4.0 5.0 X No. of Snaiis X No. OF Si{l\ILslr·!ETER ~ 1 S.E. oN t1AcRocvsTrs IN CoNTHOL AREA B FOR THE M:JNTH OF FEBRUAHY N==20 50 FIGURE 6 T. montereyi J------o--1 ~ T. pulligo 11 ~ - ~~ 21 1-D--; l 1-1)--1 .,I 1--{l--J· ..:y!; ! r-fH 4J r-0--l !-t----1 . r---0--1 (/) sf cv ~--~· 6\ r---0-1 >\_ t--t)---1 ...... (I) J;. 71I l-D-l 1-----ll---1 f "- (!) 81 ...... (1) gt 1-0-i ~--~ :::E. i-[1; -~ol' I 1--H c I 1jl }{l-.J ~ ..c ...... ~21 H}! 0. (1) ·~ 0 i3 li}1 t--S 141 1-(J----i 13 -H::; 1....,!f i{}-t j 161 ~ . ~ I 1.0 2.0 3.0 4.0 5.0 X No. of Snails X No. oF SNAILslr1ETER:!: 1 S.E. oN HL\cRocvsns IN CoNTROL AREA B FOR THE f"bNTH OF f1L\RcH N=20 sr FIGURE 7 T. montereyi ~ 11 ·t-O-t J-il-l T. pulligo t-~ .r{)-1 21 1-iH st h'J-i!-:-H i 1-{J--1 4j 1-H f (/) 1-0--l (\j 1---9----i > 'I-. 1--{}--f 1------e-----; Q) +-" 1-0-1 ..£ !-h ~.-.i 'I-. Cf"' i-OH-!i---1 (!) +-" ([) 9 1-{)-11----~ ~ 10 !-t,'"4 !--[}--I 11_ 1-0-; 1 ~~L ~ -4 ~-~ 15J ~}-! r-H 16-~i @ ~~--~~~~--~~--~~--~--~~ 1.0 2.0 3.0 4.0 5.0 X. No. of Snails X No. OF SNAILs/v:ETER ± 1 S.E. ON f'!AcRoCYSTIS IN· CoNTROL AREA B . FOR THE f.bNTH OF APRIL N=20 5.2 FIGURE 8 T. montereyi T. pulligo ..c """-' 0. 1.0 2.0 3.0 . 4.0 5.0 X No. of Snails X No. OF SNAILs/r1ETER ~ 1 S.E. oN Ni\cRocvsns IN CoNTROL AREA B FOR THE FbNTH OF ~1Ay 53 FIGURE 9 T. montereyi r----o---J T. pulligo 10 1-(H c 1-H '"111 1-()--; I 1--H i2J i--C-1 !-!'!---1 13 1--Q--J ~&-I 14 !---{}-; 1-o-----1 15; f-{}--1 1-----3-----:-1 .... c! 10""! 1----0 . I 1.0 2.0 3.0 4.0 5.0 X No. of Snails X No. OF SNAILsft,1ETER ± 1 S.E. ON f1n.cRocvsns IN CoNTROL ArtEA B FOR THE ~DNTH OF JUNE ff=20 54 FIGURE 10 T. montereyi T. pul!igo 1----'J--! ~H 1---0-----4 1-:.l---i c . . 2.0 3.0 4.0 5.0 X No. of Snaiis · X No. oF SNAILSir":ETER ± 1 S.E. oN f1AcRocvsns IN CoNTROL AREA B FOR 11-lE ~bNTH OF JULY N=20 ss FIGURE ll T. montereyi T. pui!igo c 13 !-0-1 14! 1-irl J.J 10~ j-~ I ~-{}-; 16-l H}-1 l fl I • 1.0 2.0 3.0 4.0 5.0 X No. of Snails XNo. oF Sr\lAI Lslr·BER ± 1 S. E. oN f·1AcRocYsTI s IN CoNTROL MEA B FOR THE r~bNn-t OF AuGUST i'F20 56 FIGURE J2 T. montereyi ~ 1- ,'{}! T. pulligo ~ 21D-f H-1 31-0-+~ 4 1-04~ ca(/'} I-{)-! 1---tt-----t >L H.H 1---\l----J (1) ~ .£ . 1-0-! ~~ tf"'ll L 84 n_n (!) ...... ! (!) ol HH t----+---1 ~ 1~1 1------(l-----f c I 111 a I ~ ..c..,_.. 121 t---fJ--1 1--:~ 0.. (!) 0 1-Cr-f 1---fr----1 ~~' I 1----Q-4 151 l-{Hr--~ 16.1 i-i}-! 1.0 2.0 3.0 4.0 5.0 ·X 1\lo. of Snails X No. OF SNAILS/NETER ± 1 S.E. oN ML\cRocYsTis IN CoNTROL AAEi\ B FOR THE raNTH OF SEPT8"1BER f'f=20 57 FIGURE 13 T. montereyi ~j; T. pulligo 3ll{}-! l-.\}----1 4 M}-1 1---H 5 }-Q-j 6 1{)-l tO 2.0 3.0 4.0 5.0 X No. ot Snails X No. OF SNAILs/t,;ETER ± 1 S.E. oN fjac;Rocvsns IN CoNTROL AREA B FOR THE f1lNTH OF OcTOBER N=20 58 FIGURE lLf T. montereyi t---o---1. 11~ T. p uiii g 0 J-----o----1 2-~ m 3 j-fl..r4 4 1-{H ..c: ...... 12 l--{}-1 n (1) 0 13 1---fJr-.--1 ...__-9:---J 1.0 2.0 3.0 4.0 5.0 X No. of Snails X No. OF SNA I Lsfr,1t: 1ER ~ 1 S. E. oN Nt\cROCYSTI s r N CoNTROL MEA B FOR THE r·bNTH OF NoVB'iBER N:=20 FIGURE 15 T. montereyi t--o---1 ·~ t' {}-! l T. pulligo ~I !{}! 2 !-l}-1 3 ;{)J!-i:H 4 l{!1 ~-'H (/) 5 l-{H ~--~ ~ > H:H '- 6- 1-:}-1 ..,...(JJ .£ 71 1-{}-t !c.. 8~ !---()-l ~&--r ...... (JJ (!) 91 1-'J--l ·6 ~ 101 f-{}-! 1:----!'l----t . i 11-l 1-()---l ..c +-' 12 t-()----i 0.. (!)_ 0 13 ~------1 1--{)-J . 141 t-:---a 15 ~ ~ 16j . !--{}----!. • s . . 1.0 · 2'.o 3.0 4.0 5~0 X No. of Snails X No. OF SNA 1Lsft,lETER ± 1 S. E. ON f·1i\cRocvsn s IN CoNTROL Ar<.EA B FOR THE f·bNTH OF DECE/"ffiER i'l-=20 60 FIGURE 15 Tegu/a pulligo . N= 1218 >. 0 c r w I g. 6~ If I 2~ I~ r I I , I r:...r' 0~~~------~~ 4 8 12 16 20 24 28 Size Class in mm RELATIVE FREQUENCY OF SrZE CLAssEs FOR TEGULA PULLIGO CoLLEcTED ON &_cROCYSTI S AND THE BENTHOS FIGURE 17 Tegu/a pull/go Tegu/a monterey/ 20 20 N = E384 N=247 ~'-' !!5· >. >, u u c: c: lJ C) (]) ::J :J cr 0" ~ !0 ~ 10 Ll.. Ll.. > -0 -0 ill ill ~ 51 Ct: 5 J;..;.,-3-15_1_7_19_2_1_23_2_5-27.1-J..2...:.J9 o~~~~----~------~15 17 19 21 ' 23 25 27 29 Size in mm Size in mm RELATIVE FREQUENCY OF. SIZE CLASSES FOR TEGUL8 PULLIGQ AND TEGUL8 ~O~IEREYI. CoLLECTED ON ~CROCYSTIS Tequ/a pu/ligo . Tegu/a montereyi r ~) N =5~34 N=54 >-. u c (]) !2 :J D" (]) '- LJ.... -~ 81 ~ 8 -0 (]) cr: ~ 4j 4 I 0~~------~~ 4 6 8 10 12 14 16 18 20 22 24 26 0 ~ 6 8 10 12 !4 16 18 20 22 24 26 28 Size in mm Size in mm RELATIVE FREQUENCY OF SIZE CLASSES FOR TEGJ.l.LA PULLJGO AND~ /V'O~ Cou_ECTED ON THE BENTHOS 63 FIGURE 19 Tegu!a montereyi 181 I 16i' 3J 411• N == 301 G . ! e 1?-1 ~ ·-1 ~ JO~ o- I :1 0:::~ oi i ~ ,.,1 ji . i -,?~ i oL ..----' 6 8 10 12 14 16 18 20 22 24 26 28 Size Closs in mm RELATIVE· FREQUENCY oF SIZE CLAssEs FOR TEGULA r:oNTEREYl CoLLECTED ON t'kl.C.ROCYST IS AND THE BENTHOS . 'FIGURE 20 CALLIQSIQtV:'I Ul2liDJJ.1- X" No~ oF SNJ\ILs/PtANT ± 1 S~L ·THROUGHOUT THE YEAR 3.0 T o_~ ...... 2,0 5,_. z~ (/) u_ 0 0 --.,::._ I>< 1. JAN FEB APR ~v JUN JuL AuG · SEP Ocr Nov DEc roNTHS FIGURE 21 Col/iostoma ligatum Colliostoma 30 conolicu/atum Ca//iostoma annul atum ~·' .._Q ... :>. g20 20 20 (!_) ::l g N=75 N=20 N=22 Lt I'J) ·-> 0 10 10 10 Q) 0.: - - 0 .!f'f-.l-.J-1...--...;.J 0 .1-,' ,l!...!-1..----.Jn 10 12 14 16 !8 7 9 II !3 15 17 19 21. 23 25 27' 10 12 14 16 IS 20 Size in mm · Size in mm Size in· mm RELATIVE FREQUENCY OF SIZE CLASSES FOR CALLIOSTOMA UGAI!Jlir CALLIOSTOi\'v\ CANAU.CULATUM, AND CALLIO$T0[1fl ANNULAIUM COLLECTED ON &sJiacYSIIS_ AND THE BENTHos~-· FIGURE ?2 ,.___ .. CAt ..u'"osrof18. cANAUCULATU~t ... X No, oF SNAILS/PLANT ! 1 S,E, THROUGHOUT' THE YEAR 1,5 !- a_s ...... 11 (,!) -l -~ C./) L!.. 0 £ IX 0,5 l JAN FEB l1~R APR NAY JuN JuL AuG SEP Ocr Nov · DEc M:lNTHS 67 u w ·~ I-: t=l >- w ~ 6 ~ ~ ~ (_I) I- ::J u 0 :c~ ~· w w0... (/)- U) rl +I (_I) ::J <:( f'l") ~ N ...... __CL LU cq _J a: ...... ::J ::J ...... , ----;, (_I) U) ...... ~ :c L.L. U) I-z I.L 0 z ~ ::J ----;, 0 - 2: t>< ~ 0::: ~ & ~ ' U, ffi ~ LL 0 rl 68 FIGURE 24 SIZE CLAss/DISTRIBUTION OF TEGULA .E:!Jll..Uill. 60 BY 3 METER DEPTH INTERVALS SIZE CtASS 23 f!M f\b54 22 t"M _Q f\6 81 60 (/) (/) u:s UJ N . ,___. 21 ~'N (/) <( 0~ N=l98 LL HJI 0 t: I UJ u cr: I UJ I o._ 28 t ol 6 6Cl ~ 163 19 Y"o~YI rt=lll 18 fYIN 0 I ~I N=62 .fv1 L M t'l G-3 3-6 6-9 3 METER DEPTH INTERVALS oF f1L\cRocvsrrs FRor-1 THE SuRFACE CANOPY To THE Ba-rn-lOs · 69 FIGUF SizE CLAss/DISTRIBUTION OF IEGULA f10NTEREYI BY 3 f'1ETER DEPTH INTERVALS SIZE CLASS 25 fiN N=87 50 I (!)50 U) 5 u 23 l"l'-1 w N ...... (.1) N=l06 22 f'/1'1 N=83 21 M'1 N=71 20 !1~'1 N=33 6-9 H 9-12 t~ 12-15 M 3 f·1ETER DEPTH INTERVALS OF Nl\CROCYSTIS FR~X1 JHE SURFACE CANOPY TO THE BENTHOS .70 nean Den!:ii ty E< rrec_.ttwncy of 'fhrc0 s;Jecies of 'fequla and Three species of C<.tll io.sto:r: Teq~t_!~ 'l'eg:ula 'l'c.9u1a Calli o:-1torr:o Calliostoma· Calliostoma pullio~· !';ontcreyi brunnea liq21t~m ~d.;;;tum cc;nalicuJ.aturn (JA!·~) Pensity 2.1 .84 .02 .05 .02 + Frequency .64 .45 .02 .04 .02 + (I:'ES) Densit:!{ 2.4 • 77 .O.l + + .01 FrcquE".nc;y • 67 .44 .01 + + .01 (r-l!~R) I + Frcq:..le:IcyD_c_r_ls_~_·t__ y---+~l---~-o • 62 ___II_____ ;,n~__ 6_5 __ -;~-·-0_l.01__ -+-----·-o_l .01____ -+------+ (M'R} ~ -r------Density .l 9 57 I + + + + _F-:-r_c_q_t_te_·._-::_c_y-+-.-·_6_o :40 + + + + ( ;-;p,y) • f Dmsit )' l. 9 I .56 i .O.l + + Frccr...~ency • 69 • 39 .01 + + (JUN) De~·1.s.i ty .98 .74 .08 .03 .04 .51 Freqc1ency .47 .05 .04 .03 (JUL) Density .98 .49 + .13 .0~ .os Freqttency .41 .34 + .09 .04 .OS ( i'.UG) Density 1.1 .41 .01 :08 .03 .08 Freque;'lcy .54 .30 .06 .03 .07 ($EP} Density 1.-1 .01 .15 .20 ~06 . 60 . Il .01 .09 Frequency .10 .06 i ------~------4r------~-----+------;------r-----~·---- (OCT) l Density I 1. 6 ... 60 - .10 .03 ... OG _F_r_e_~_~~-<~_~_Y__ 1f--·-6_4 ___ f-- __.3_4 __ ~~------+----·-0_7 _____ r-___._o_J _____ r ___._o_ 4______{tWV) Density 1.7 1 .72 - .02 .03 .02 Frcquer1cy 1 .63 • .<;.0 - .02 .03 .02 (DEC) Density 2.0 .86 .01 .07 .01 .03 Frcc_:uC'ncy .68 .48 .01 ,.o.:; .01 .03 ======-==-=='=== ---L. Sex Ratio of ~la EUlliq~, Tegul~ monter~yi, and Calli?stoma ligatum ______... .-....!_,.. _____...,.,,_ -. --"~·-r---·--·-- 15m•20 mm 20-25 mm :> 25 mm Size Class Size Class Size Class Species N % Male % Female % Male! % Female % Male % Female % Male % Female Teoula :eulligo 380 45 55 46 54 48 52 33 67 Tegyla monterey_i 89 41 59 27 73 48 52 33 67 Calliostoma ligatum 47 62 38 59 41 - - - - 72 TABLE 3 Percent Frequency of Occurrence of the Three Species. of Calliostoma on r'lacrocystis by 1 Heter Depth Intervals Ca11iostoma Calliostoma Calliostoma. liaatum annulatum. canaliculatum DEP'Yd % FREQUEi:\ICY % FREQUENCY. % FREQUENCY 15m 9, 2~S ~ 1 .. 9% 14m 11D3% 1~4% 2 .. 8% 13m 14% 3% 1 .. 9% 12m 6~7% 7.4% 5.7% llm 14% 10~3% 3.8% 10m 14.4% 5.9% 8.5% 9m 9~0% 7.4% 10 .. 4% 8m 7. 11 .. 7% 14.2% 7m 3"'';:c. 10.3% 6 .. 6/~ 6m 5.6%. 8 .. 8% 9.4% 5m l&o S~b 10.3% . 18% · 4m 1% 5. 9~1: 5.7% < 3m 1% 5 .. 9% 7 .. 5% 2m .: 5~~ 8.8% 3.8% . lm 1% 3% - N= 194 N= 168 N:= 106 TABLE 4 Two-tailed Mann-~vhi tney U Tests of Mean Densities of Four Minor Species Before and l~.fter liarvest in Areas C & D NULL HYPO'l'HESIS (Area C) - No significant diff. in X tt of snails/plant u Obs. U o<...(n1 ,n2 ) Significance ----~---~ .... -- -- T. brunnea before & aLter harvest u 100 - - UQ 05 (15,15) 61 p > .05 _____ ,_....___ '"'"'''_..... _..... _____ ,_ --.. ·--·---... -·, --·~--- c. lioatum before (.)t after harvest. U' ::::: 132 u or-:(15,15)=161 P >.as - ~ :J __ ..,.._... .. --·-~··-- c. annul a tum before & after harvest - u = 120 u. 05 ( 15 t 15 )=161 p >-05 c. - canaliculatum before & after harvest u = 153 u:osClS,l5)=161 p > .05 NULL HYPOTHESIS (Area D) No significant diff. in -X 4i= of snails/plant u Obs. u (n1,nz) Significance 'I'. }:)runnea before & after harvest u 100 - = u_ 05 (15,15)=161 p > .05 ,., -'-• ligatum before & after harvest u = 127 u. OS ( 1S ,15 )=161 P .>.05 c. annul a tum before & after harvest u 120 - = u. 05 (15,1S) 61 P :> .• OS c. canaliculatum before & after harvest u :::: 125 u. (1S,l5)=161 p :>. 05 - 05 1 * Reject Null Hypothesis 74 TABLE 5 Abundance of Tequla pulliqo and Tequla montereyi in Area C Before, After, 1 IYlonth and 6 t-lonths Following the t1echanized Harvest of the Area BEFORE HARVEST AFTER HARVEST - N=l7 N=l7 · 'I'eQl.lla I Tequla Tegula Tequla EU.L'1' lQO I monterevi Eulligo montereyi ! Density .. o::;rr, 1.3 .81 .83 Relative Density 32% I 61% 46% 47% Frequency .. 39 I .. 61 .. 42 .. 51 i Relative I Frequency 34% 53% 40% 48% -X# o£ S/P, +- 1 S.E .. 10.6 + 1.6 21 .. 4 + 3 .. 3 13 .. 2 + 2 .. 1 13.5.± 1.4 I I I I' I, l f!lONTH AFTER HA~VEST 6 NONTHS AFTER HARVEST N=l7 ·N=l7 1'egu_:l_a ~~' Tequla Tequla Tegula pulliqo rnontereyi pulligo Imontere::d:_ Density 1.2 .7 1.7 .93 Relative Density 59% 33% 61% 34% Fr~quency .57 .41 .. 64 .52 JWlative Frequency 50% 36% 50% 41% -X# of S/P, ± 1 S.E. 20.53 ± 4.1 11.5 + 1.7 28.6 + 6.2 16.2 ! 2.2 -- Density == X # of snails/meter Frequency :::: X ~f of occurrences/mete:c TABLE 6 Two-tailed Hann-Whi tney U 'rest of Before and After Harvest Distributio!la1 Data From Area C for Tegu1a pu11ig~ and ~u1a montereyi NULL HYPO'l'III!~.S IS {Area C) I No significant diffQ in distribution u Obs~ U r;(.. (nJ.,n2) Significance ... _.... ______._...._.., ...... ,.,.,....,._ ,.,_,...... ,... ______- ..··--·----- ,---·------ T. pulliqo immed. before & after u 155 (17,17)=202 p .05 - harvest = u_ 05 > T. oul1ioo 1 month after harvest u = 206 u. (17,17)=202 p 05 * - 05 <. T. Eullioo 6 months after harvest u = 187 u_ (17,17)=202 p >.05 - 05 T. monterevi immed.before & after harvest u = 208 C17,17)=202 p <.05 * - u_ 05 T. montereyi 1 month after harvest 227 - u = u_ 05 (17,17)=202 p <. 05 * T. monterex:i 6 months after harvest u :::: 239 - u. 05 (17,17)=202 p <-05 * * Reject Null Hypothesis TABLE 7 Two-tailed l\!ann-Hhi tney U Test·. of the Distribution of Teaula pullig:o and ~Cc.:....CJ:::.lla. rnontereyi in Control Area B Before and After the Harvests in Areas C and D NULL HYPO'E-mSIS ( A~·rea C) No significant diffG in strib'u:tion u Obs .. Uo<.(n1 ,n2 ) Significance _.__,.,.... _____ ..,...... -...... ___ .. ,_.,..,_ __ _.,. ___. ----- T. ;eulliqo between June & July u 136 (20,20)=273 - -- u_ 05 P> .05 T. monterevi bet\veen June & July u = 125 u or: c20,20 )=273 p >.05 - • ::J NULL HYPOTHESIS (Area D) No significant diff. in ·distribution u Obs. u (n1~n2) Significance T. pulliao between Sept .. & Oct. u_ (20,20)=273 p > .05 - u = 220 05 & 210 (20,20)=273 p > T. monterevi bet\veen Sept. Oct. u = u_ 05 .os * Reject Null Hypothesis 77 'l'l\BLE 8 Abundance of Tegula pulliqo and.Tequla montereYi::_ in Area D Before, After, 1 Month and 6 fiionths Folloving the Nanual Harvest of the Area · BEFORE HARVEST.r AFTER HARVEST N=l6 N==l6 'regula :regula Te~la Te~la pulliao rnontereyi pulligo rnon·tereYi: Density 1.4 .. 56 2. 6. 1 .. 0 .. Relative Density 67%' 27% 69% 28% Frequency .. 58 .. 35 .. 75 .. 43 Relative Frequency 57% I 34% 59% 34% -X # of S/P, ± l.S .. E. 23. 3 :: 2. s I 8.4 ± 1.4 I 1 1'10NTH 1\FTER HARVEST 6 l'·10N'I'HS AFTER HARVEST N=l6 N=l6 Tequla ::r'ecp..lla Tequla Tequla ;eulligo mon·tereyi ;eulligo I mont~ Densi,ty 1~9 .. 76 1~8 .. 54 Relative Den.sity I 69~S 28% . 76% 2"1"'"-P Frequency· • 69 .. 41 ..59 .. 35 Relat·ive I Frequency 60% 351; 61% 36% - 4): I X of S/Pr + + + :l.S.E. 30o4 + 4.3 12.2 - 1 .. 9 32.1 - 3.4 9.4 +- 1 .. 5 "''P Density = X # of snails/meter Frequency = X ~f: of occurrences/meter TABLE 9 Two-tailed f>1ann-Whi tney U Test of Before and After Harvest Distributional Data :From Area D for Tegula pul,liao. and :regul~ monterevi NULL HY.PO'l"'IESIS (Area D) No significant diff. in distribution u Obs .. . U c<. (nl ,n2) Significance ---..- ...... ,.... _,__ _.. __,,, .. .__....,,.,.,, ... _.._...... -...... _.. -·- -·-·-·--·------·--·-·- -T. :eulligo immed. before & after harvest u - 217 u.os(l6,16)=181 p <. 05'\- T. month after harvest u 189 - ou1liao 1 = . u. 05 (16,16)=181 P <·OS* T. 6 months after harvest u 168 P - J2U11iqo = u. 05 (16,16)=181 >.OS T. montereyi immed.before & after harvest U=191 .. S - u_ 05 (16,16)=181 P <·OS* T. montereyi l month after harvest u = 161.S - u " 0 5 ( 16 ·t 16 ) = 181 P.> .05 months after harvest P> T. montereyi ·6 u = 179 u. 0s(16,16)=181 .05 *Reject Null Hypothesis 79 Tl~BLS 10 Index of Relative Importance for Ophiodon elongatus N=7 X Size 632 mm T. L~ ( 550-660 mm) N -v F --IRI FOOD l'l'EN - (%) (%) . (%) . HOLLUSCA Cephalopoda: 1 Octopus sp. (bc.a,_"'- r-..~' 4 33 .Sml - 2 20 660 {animal) 2 16 33ml 52 2 20 1360 Gastropoda: Calliostoma .§£· 1 8 tr. - 1 10 . 80 Nassariu.s __...... so. I 1 8 .Sml - 1 10 80 I CRUS r:PACEl\. Pagurid crab & shell 1 8 lml 1.5 1 10 95 Loxorhynchus c:rispatus 1 8 lml 1.5 1 10 95 Il CORD1\ 'I'l;. i Unidentified fish: 1 8 28ml 44 1 10 520 Otolith: 1 8 - - l 10 80 Sfu"\TD GRAINS & DE11Rir.rus - - .Sml - ·1 10 - ; 80 lncl~~>: of Hcla ti ve J m_p::..n:: Lance for: N~11 X Si2c = 347 ~n ~.L. {315-427) -v --:r· (%) (%) (%) -----·----·----- cnu~~.i'.CE~ Shrimp: H er~.. ~~c~~~'::. E.2 • ·2 2 2ml 1 2 3 9 Spir~_r.:~2.C:.~_n:h; EE..~onot<:: 3 3 2.3ml 1 3 4.5 13.5 Unidcntif:icd shrimp 7 6.5 l.2ml - 1 1.5 10 Crabs: ! J,o;:o.::-hY._ll.~2~ s;:::-ispatu_!i 8 7.5 l2:nl 7 4 6 87 Puq~_2_! ~:QE· G 5.5 4.3ml 2.5 3 4.5 36 Nir.:·.l-!_1:!..~ foliatus 1 l .8ml - J. 1.5 1.5 Xcm.thinicl cr~cb 1 l .5ml - 1 1.5 1.5 :Isopod a: _!dot_ea 2 2 lml .. 2 3 6 A:11;?h i pod u. : cor0p!-d.oidac 6 5 .. 5 1ri11 - 1 1.5 8~25 G<. Polypl.::;.coplJO=a Chiton V'Jlvc 1 ·- - - :t 1.5 1.5 Gc.strop-:x:1a: .. Tc~Jla__ _..:..J_,.,. __ -·so. 5 5 3ml 1.7 ;;.> 7.5 50.25 !.L~~,l i 0 J.: is §?. • 1 1 3Ial 1.7 ]_ J..S 1.5 !~C!E~~~_Q})O:;:a .92.. 1 1 .Sml - 1 1.5 2.5 Bivalvia: Cephalopoda: Octopu~ 10 9 - - 5 7.5 67.5 5 5 52ml 30 4 6 :no Glyceridae ( - 3:nl 1.7 3 4.5 7.7 ~_liiNODF:R\·1.!\'i'~ F;dmroidv.: 2 6:nl 3.5 2 3 16.5 - 4.5r:Jl 2.6 2 3 s FIS!l EGGS - 3ml 1.7 1 1.5 1.5 ALG.!.B --t:}_e..r::~o_E~_!:is sporophy11s J.O 9 3ml 1.7 2 3 32 ------....-CH0:1.D.;'N\ F:i sh: G:ibl•onsia t:.P· 2 2 lG:,,l 9 2 3 33 CottT&~-;- 2 2 )0;~1 S.B 1 1.5 12 '!'.'~otT:, l .. 17.::!.. ~----~--- lO c. 9 90 ~----~·- 81 TABLE 12 Index of Relative Importance for Damalichth~ vacca N=1 Size 389 mm T.L. I N v F I - - - IRI FOOD ITEN I (%) (%) (%) I I I CRUSTl~CEA Brachyuran crab:· 2 18 4m1 12 1 20 418 Crustacean rragments: - - Bml 25.8 1 20 516 ECHINODEH1"1P{l'A I Ophiuroids::: 5 f 45.5 15ml 48.4 l 20 1886 i I ' HOLLUSCA Gastropoda:: I 'l'equla pl]1lig·6 I 2 18 2.5ml 8 1 20 520 Ca11iostoma licrc.tum I 2 I 18 2.5ml 4.8 1 20 456 I l