Pacific Science, vol. 54, no. 2: 137-147 © 2000 by University of Hawai'i Press. All rights reserved

Floristic and Biogeographical Trends in Seaweed Assemblages from a Subtropical Insular Island Complex in the Gulf of California 1

2 2 L. PAUL-CHAVEZ AND R. RIOSMENA-RoDRIGUEZ ,3

ABSTRACT: Floristic and biogeographical trends of the seaweed assemblages in subtidial rocky areas were evaluated at 10 sites around Espiritu Santo Island in the Gulf of California. Seasonal sampling in two consecutive years with in­ tensive surveys in a 500-m2 area at each site was done. An intensive search was made of previous records from the literature. We found 85 species in the field with an additional 69 species from the literature, for a total 116 species. Species composition was significantly different between sides of the island in the first year, but very similar in the second. Species composition was not influenced by the presence of epiphytes. Phenologically, most species were ephemeral or annual with a low reproductive effort. Biogeographically, tropical elements dominated, but there was an important contribution from temperate species. Our results indicate that Espiritu Santo Island is a dynamic system that is strongly influenced by local oceanographic conditions.

INSULAR SYSTEMS IN the eastern Pacific area Studies of insular systems in the Mexican are poorly known (Stoddart 1992); only a few Pacific have been restricted to Guadalupe Is­ systems have been studied intensively (e.g., land (Stewart and Stewart 1984), the Todos the Channel Islands in California [Murray et Santos complex (Aguilar-Rosas et al. 1990), al. 1980] in the Northern Hemisphere, Easter Rocas Alijos (Silva et al. 1996), and the Island [Rapa Nui], and the Juan Fermindez Revillagigedo complex (Leon-Tejera et al. Archipelago [Santelices and Abbott 1987, 1996). Some of these studies describe the Santelices 1992] in the Southern Hemisphere). species composition and others the affinities Those studies were devoted to understanding of the flora. None examined the dynamics the organization of the assemblages in a bio­ of seaweed asssemblages. geographical context. However, other fea­ The Gulf of California has a relatively tures may influence the organization and dy­ high number ofinsular areas (Villa 1988) that namics of the flora, including temporal or are increasingly affected by tourism. As a re­ spatial patterns in distribution (Neto and sult, the Mexican government is developing Farham 1995), the influence of the epiphytes strategies for the protection and management On the overall biodiversity (Smith 1992), and ofthese areas as a priority region (SEDESOL phenology/reproduction (Mathieson 1989). 1994). Prior knowledge of the species dis­ These features have not been documented for tributed in insular systems in the gulf comes the eastern Pacific. primarily from observations made during cruises sponsored by the California Academy of Sciences (Setchell and Gardner 1924) and _lThis study was partially funded by theComision­ a few· additional -contributions by Dawson Nacional para el Conocimiento y Uso de la Bio­ (1959), Norris (1972), Norris and Bucher diversidad (CONABIO grant FBI45/PI09/94 to R.R.R.) and a scholarship from Universidad Autonoma de Baja (1976), and Riosmena-Rodriguez et al. California Sur (granted to L.P.C.). Manuscript accepted (1998). More recently, Foster et al. (1997), I March 1999. Reyes-Bonilla et al. (1997), and Riosmena­ 2 Herbario Ficologico, Departamento de Biologia Rodriguez et al. (1998) have shown that rho­ Marina, Universidad Autonoma de Baja California Sur, Km 5.5 Carretera al Sur, La Paz, B.C.S., (fax: dolith beds are widely distributed around the (112) 1-18-80; E-mail: [email protected]). islands in the area. Furthermore, the insular 3 Correspondence author. complex Espiritu Santo-La Partida is 10- 137 138 PACIFIC SCIENCE, Volume 54, April 2000

cated in a transitional zone where oceano­ the Phycological Herbarium of the Autono­ graphic conditions may determine the bio­ mous University of Baja California Sur geographical affinities of the marine flora (FBCS) according to procedures in Riosmena­ (Dawson 1960). Thus, the goals of this study Rodriguez and Siqueiros-Beltrones (1994). were to determine the temporal and spatial Historic reports from the area were compiled dynamics of seaweed assemblages of the from the literature (references are cited Espiritu Santo-La Partida complex and to in Riosmena-Rodriguez and Paul-Chavez determine their biogeographic affinities. 1997). These, and the species collected in this study, are included in a taxonomic list (Ap­ pendix) following the systematic arrangement MATERIALS AND METHODS in Riosmena-Rodriguez and Paul-Chavez (1997). Study Area Espiritu Santo-La Partida is located in Data Analysis the southernmost part of the Gulf of Cali­ fornia (24° 30' N, 110° 21' W), northwestern A presence/absence matrix by locality was Mexico (Figure 1). The subtropical nature of constructed based on the collected species. the region is defined by transitional oceano­ The species distribution among localities and graphic conditions influenced by the cold times was determined by season and year for California Current, the warm eastern tropical each of the 10 localities. This was based on Pacific water, and the warm Gulf of Califor­ overall number of species, and by taxonomic nia water (Alvarez-Borrego 1983). Overall division, arranged by green, brown, and red productivity measurements are representative algae. An independent goodness of fit test of an oligotrophic zone (Round 1964). Up­ (chi square) was used to compare species welling events occur along the littoral of the richness by division between the protected bay during spring (most intensely) and in and unprotected sites (n = 10) by year. Jac­ summer (Marignione 1988). Those events are card's index of similarity was used to com­ associated with northwestern winds in spring pare localities by year. The resulting matrix and with southeastern winds in the summer was used in a cluster analysis, to represent (Alvarez-Borrego 1983). The western shore the similarity between sites in a dendrogram. of Espiritu Santo Island is protected from Also, the percentage of species in each divi­ gulf waves and has gentle slopes, but the sion per season was plotted from each local­ eastern shore has steep slopes exposed to ity. Because of the clear differences among wave action. Ten sampling sites were located exposed and protected areas, representative along the margins of the insular complex in sites for each are presented. rocky areas (Figure 1). Based on the presence/absence matrix, a longevity category was assigned to each spe­ Field Work cies as defined by Mathieson (1989), and the percentage of each group was plotted for Seasonal sampling was conducted from each locality. The reproductive state of each April 1990 to October 1991. Winter sampling species was also determined by locality/sea­ in 1991 was not carried out because of cli­ son by a careful external examination of the matic and logistic problems. Intensive quali­ specimens and with cross sections where nec­ tative surveys were made in the intertidal and essary. Mter determining the reproductive subtidal zones (to 5 m depth) within an ap­ state of each specimen, a calculation of the proximately 300-m2 area by skin diving dur­ percentage of each state (vegetative or repro­ ing high tide. Special precautions were taken ductive) was also plotted. Information about to collect and properly preserve the fragile, habit (epilithic or epiphytic) was recorded filamentous specimens and those epiphytic on and analyzed graphically. Biogeographical other seaweeds. All material was transported affinities of the species were assigned to four to the laboratory, processed, and deposited in categories (tropical [Tr], temperate [T], cos- N

La Partida ---

Santo

,. ... .:':.,,: .: .....:..".~. :'

FIGURE 1. Study area and sampling sites (I, La Partida; 2, San Gabriel; 3, El Cardonal; 4, Candelero; 5, La BaI­ lena; 6, La Lobera; 7, Punta Sur; 8, Morrito; 9, El Faro; 10, El Pailebote). 140 PACIFIC SCIENCE, Volume 54, April 2000

50 the second year, with 42 species on the ex­ PROTEt7ED EXPOSED posed side versus 32 for the protected side ~ 40 (Figure 2). This pattern also is clear in the C3 w cluster analysis (based on the values of Jac­ fu 30 card's index), with a significant separation lLo (0.8) in the taxonomic composition between ffi 20 the protected and exposed zones in 1990 III :!E (Figure 3). The chi square test of indepen­ ~ 10 dence using species richness by division also indicated significant differences in number of o r r 2 4 5 3 7 10 9 8 6 species by division between sides in 1990 SITES (0( = 0.05, df = 2). The distribution was more equitable between exposures in 1991, with no distinct floristic separation (Figure 3). FIGURE 2. Number of species by site (numbers as in During analysis of the temporal variation Figure 1) and year. within the localities, we found that, as in the spatial scale, seasonal patterns in the assemblages could be grouped as protected mopolitan [C], and endemic [ED based on versus exposed side; differences were also their distribution; then the number of species found related to taxonomic category (divi­ in each category per year from each division sion , Phaeophyta, and Rhodo­ were plotted. The classification of the species phyta). On the protected side, green algae list follows the disposition and literature pre­ showed a seasonal change, with highest spe­ sented by Riosmena-Rodriguez and Paul­ cies number during winter of the first year Chavez (1997). and in summer of the second (Figure 4). Brown algal species maxima occurred in spring in both years, with minima in summer RESULTS (Figure 4). For red algae, maximal numbers A total of 116 species of macroalgae has were in autumn in both years, with a marked been collected on the rocky shores of Espiritu increase in the first year and less in the sec­ Santo-La Partida (Appendix). Comparision ond (Figure 4). of species found in the bibliographic review The richness of species was very different and our collections yielded 25 species col­ on the exposed side of the island between lected previously but not by us, 16 previously years. In the first year, green and brown al­ and by us. Sixty-nine taxa were identified in gae were only present in spring and winter; our collections and they represent new re­ red algae appeared in summer and the flora ports for the area. During 1990-1991, we decreased in number in the autumn. In the found 85 species, 11 % of which were chlo­ second year, the maximal numbers of each rophytes, 28% phaeophytes, and 61% rhodo­ division occurred in different seasons: sum­ phytes. The average number of species found mer for green algae, spring for browns, and per year was lower, with 70 species found in autumn for reds (Figure 5). The seasonal 1990, of which rhodophytes composed 57% trends in the second year had a pattern simi­ of the total. Sixty-eight species were collected lar to that of the protected side in both years. . in-199l··even though there was no winter­ The observed seasonality- could be explained survey. Rhodophytes also dominated in by the phenological patterns observed for 1991, composing 66% of the total. most ofthe localities in both years (Figure 6). The observed species richness differed de­ Green and brown algae were only repre­ pending on the side of the island and the sented by sporadic and pseudoperennial year. In 1990, more species were found along (= annual thalli) species, and red algae by the protected side (47) versus the exposed both groups and a few perennial. Green algae side (25) (Figure 2). The inverse was found in ar@ the major component in the pseudoper-

'''' .. , ".",,, ,,.., .. -.. ,...... Trends in Seaweed Assemblages-PAUL-CHAVEZ AND RIOSMENA-RoDRIGUEZ 141

I I • • A 1 4 I

2 I 3 -, I 5 -oJ

7

9 'n ~ 6 ,~ I 8 J 10 1 I I ( 0.8 0.6 0.4 0.2

. I . 1 I B 5 I 6 I 3

10 I-- 4 7 I 2 I 9 8

I I I I

0.5 0.4 0.3 0.2 0.1 o

FIGURE 3. Similarity among sites and years for all algae (numbers as in Figure I). A, 1990; B, 1991. ennial group and the reds in the sporadics year. By the summer of 1991 there was no (Figure 6). Reproductive structures (sporo­ reproduction, and then a small increase oc­ phytic and gametophytic) on "all"" the species curred in fall, but not more than 1%. during the study period were rare « 10%) in The proportion of species found as epi­ 1990, and even rarer in the second year phytes was only around 15%. Few species (~2%). The species found to be reproductive were observed growing both epilithically and were brown and red algae; no reproductive epiphytically. No epiphytes were observed in structures were observed in green algae with the autumn of either year. In 1990, most epi­ our sampling regime. The percentage of spe­ phytic species occurred in winter (Figure 7). cies reproducing decreased during the" first In both years spring and summer had low 142 PACIFIC SCIENCE, Volume 54, April 2000

80 100 ~ 90 ~ 80 060 9 ..J ~ u. 70 U. o 60 0 40 ~ I- 50 z ~ W 40 30 ~ 20 ffi w ~ Il. 20 ~ 10 0 o -I--..L-.= S w S ES SP PE SEASON LONGEVITY IDG~B.RI

FIGURE 4. Seasonal change of species (S, spring; Su, FIGURE 6. Major phenological groups (ES, sporadic; summer; A, autumn; W, winter) between years of the SP, pseudoperennial or annual; PE, perennial) among al­ major algal divisions on the exposed side (G, green al­ gal divisions (keys as in Figure 4). gae; B, brown algae; R, red algae).

30r------100 ~ 25 ~ 80 o 0 20 ..J it U. u. u. 60 ~ 0 15 I- z Z 40 ~ 10 w a: a:0 w w 20 Il. 5 Il.

0 o w S W S Su AWS Su AW SEASON SEASON FIGURE 7. Seasonal variation in proportion of epi­ phytic species (keys as in Figure 4). FIGURE 5. Seasonal change of species on the pro­ tected side (keys as in Figure 4). mopolitan ones, but in reds there is a pro­ portion of temperate and endemic elements proportions of epiphytes (10% or less of the present. In the case of brown algae, temper­ species). ate elements represent the second major Biogeographical affinities of the flora in group followed by the endemics and with the the insular complex were similar spatially lower proportion present in the cosmopolitan "and betweellyears: outllot oetween the" rna:' "spe·cies (Figure 8). jor taxaoconsidered; most of the groups have a major'proportion of tropical elements with similar. values (Figure 8). The proportion of DISCUSSION cosmopolitan species was larger in greens and reds. The difference between these The rocky areas of the Espiritu Santo-La groups is that in the greens the percentage of Partida complex have about 45% of the total temperate elements is similar to that of cos- species reported for La Paz Bay (Riosmena-

LZl&t Trends in Seaweed Assemblages-PAUL-CHAVEz AND RIOSMENA-RODRIGUEZ 143

60 complex show strong changes in space and I_GOB DR] time. This has been suggested in the literature 50 ~ (pielou 1981), but only a few pieces of evi­ dence are related to seaweed assemblages g 40 -~ "" ~h (Neto and Farham 1995). 0"" 30 The above pattern may be explained based Eo< f~ on the high proportion of sporadic or pseu­ Z ."-l - 'ij doperennial (= annual sensu Mathieson U 20 ~ ,.- It ~ n u 1989) species observed (Figure 6). This is in - II' ,If: Il:: 10 "I 71i I, contrast to other seaweed assemblages in the .iif It· iii i' northwestern areas of La Paz Bay, where m, ~ i!l Iii 0 -,;.;.:; most of the sporadic and pseudoperennial c E T Tr species are epiphytes and play a major role in the seasonal fluctuations of the flora FIGURE 8. Proportion of the major biogeographic (Riosmena-Rodriguez et al. 1995). Further­ components (C, cosmopolitan; E, endemic; T, temperate; Tr, tropical). more, this pattern is also clearly different from that of other insular systems where the rela­ tionship of epiphyte:epilithic taxa is about Rodriguez and Paul-Chavez 1997). The 50% (Smith 1992). In our case the influence overall number of species (116) in this com­ of epiphytes on the overall biodiversity and plex is similar to that in the Todos Santos its spatial and temporal variation was lower complex (Aguilar-Rosas et al. 1990), but than 20% during most of the study period much lower than that in (Figure 7). The heterogeneity observed in the (180 in Stewart and Stewart 1984) or the floristic composition in the first year and the Revillagigedo complex (232 in Leon-Tejera homogeny in the second year may result et al. 1996). from emigration of some species from the Santelices and Abbott (1987) have shown protected to the exposed side and from re­ that other insular systems in the eastern Pa­ cruitment. However, this is only a partial ex­ cific with a similar geological age have simi­ planation because of a low proportion of lar numbers of species. The maj()r differences fertile taxa in both years, suggesting patterns between the number of species registered in resulting from the regeneration of holdfasts our study and that of most of the islands or by inmigration from other areas (Sante­ previously studied are related to the number lices 1990). of sites and habitats sampled, the search Smith (1992) suggested that oceano­ effort, and the size of the island. At Espiritu graphic variation influences the arrival of Santo Island, we only sampled rocky areas. new elements to insular systems and changes But recent surveys in mangrove areas in water masses influence the survival of in­ (R.R.R. and L.P.c., unpubl. data) and rho­ dividuals in the assemblages (Mathieson dolith beds (Riosmena-Rodriguez 1996) in­ 1989). The influence of the major water dicated that these habitats may contribute at masses in the Gulf of California varies least 72 more species. among years (Bray 1988), producing changes The assemblages were clearly different in in the intervals in which particular temper­ protected and exposed areas the first year, atures can be present in the~rea. In "cpld" but not in the sec6no (Figures 2 and 3). Sea­ years the difference in temperature between sonal trends were similar in both years on the summer and winter is 16°C and in "warm" protected side, with a clear maxima in one years the difference may be only 5°C season (Figure 4). Seasonal trends were dis­ (Jimenez-Illescas 1996). Furthermore, the similar on the exposed side in both years changes in water masses also produce epi­ (Figure 5), but the sides were more similar sodic nutrient availability depletion (Alvarez­ spatially in the second year. Seaweed as­ Borrego 1983). The heterogeneous nature of semblages in the Espiritu Santo-La Partida the seaweed assemblages in the insular com- 144 PACIFIC SCIENCE, Volume 54, April 2000 plex no doubt reflects the prevailing oceano­ DAWSON, E. Y. 1959. Marine algae from the graphic conditions, including upwelling re­ 1958 cruise of the Stella Polaris in the Gulf lated to wind patterns (Marignione 1988, of California. Los Angel. Cty Mus. Con­ Fernandez et al. 1994). trib. Sci. 27 : 1-39. Oceanographic conditions may have had a ---. 1960. Symposium: The biogeogra­ major effect on the biogeographical affinities phy of Baja California and adjacent seas. of the island, with the predominance of ele­ Part II. Marine biotas. A review of the ments from tropical areas within the major ecology, distributions, and affinities of groups present (Figure 8). The proportion of the benthic flora. Syst. Zool. 9 (3-4): 93­ endemics was low ("" 14%) in both years, 100. similar to other coastal (Murray et al. 1980, FERNANDEZ, B. M. E., M. A. GOMEZ, and A. Littler et al. 1991) and some oceanic islands M. CRUZ. 1994. Estructura termohalina y (Santelices and Abbott 1987, Leon-Tejera et flujo geostrofico, en el Golfo de Califor­ al. 1996). This is in contrast to the Juan Fer­ nia, durante 1992. Rev. Invest. Cient. mindez complex, where the proportion of Univ. Autonoma Baja Calif. Sur 20: 123­ endemic species is high ("" 30%), although 286. species richness is low (116 species) and thus FOSTER, M. S., R. RIOSMENA-RODRIGUEZ, similar to the Espiritu Santo-La Partida D. L. STELLER, and W. J. WOELKERLING. complex, suggesting that dispersion distance 1997. Living rhodolith beds in the Gulf of for species to colonize islands is also com­ California and their implications for in­ bined with the degree of oceanographic iso­ terpreting paleoenvironments. Geol. Soc. lation, and not only with their age and geo­ Am. Bull. 138: 127-140. graphical position (Santelices 1992). JIMENEZ-ILLESCAS, A. R. 1996. Amilisis de los procesos barotropicos y baroclinicos en Bahia de La Paz, RC.S. Ph.D. thesis, ACKNOWLEDGMENTS Universidad Nacional Autonoma de Mexico. We thank M. S. Foster and E. Serviere for LEON-TEJERA, H., E. SERVIERE-ZARAGOZA, their valuable advice throughout the study and J. GONZALEZ-GONZALEZ. 1996. Affin­ and two anonymous reviewers for their com­ ities of the marine flora of the Revilla­ ments. We also acknowledge the field assis­ gigedo Islands, Mexico. Hydrobiologia tance by the UABCS Phycological Herba­ 326/327: 159-168. rium staff. R.R.R. acknowledges Alejandra LITTLER, M. M., D. S. LITTLER, S. N. MUR­ Angeles-Perez for all her support during this RAY, and R. R. SEAPY. 1991. Southern study. California rocky intertidal ecosystems. Pages 123-134 in A. C. Mathieson and H. Nienhuis, eds. Intertidal and littoral eco­ LITERATURE CITED systems. Elsevier, The Netherlands. AGUILAR-RoSAS, R., I. PACHEco-RUIZ, and MARIGNIONE, S. G. 1988. Una nota sobre la L. E. AGUILAR-RoSAS. 1990. Algas mari­ variabilidad no estacional de la region nas de las islas Todos Santos, Baja Cali­ central del Golfo de California. Cienc. fornia, Mexico. Cienc. Mar. 16 (2): 117­ Mar. 14(4): 117-134. 129. MATlllESON, A. C. 1989. Phenological pat­ ALVAREZ-BowGo, S.'1983. Gulf ofCilifor~ terrisoCnortheni'New England seaweeds. nia. Pages 427-429 in R M. Ketchum, ed. Bot. Mar. 32: 419-438. Estuaries and enclosed seas. Elsevier, MURRAY, S. N., M. M. LITTLER, and I. A. Amsterdam. ABBOTT. 1980. Biogeography of the Cali­ BRAY, N. A. 1988. Water mass formation in fornia marine algae with emphasis on the the Gulf of California. J. Geomorphol. Southern California islands. Pages 325­ Res. 93 (C5): 4993-5020. 339 in D. M. Power, ed. Proceedings of a

• '''''. • " ..., ~-., OJ'" ,..,. ,' • ..., "'"'' 'u '''"''' Trends in Seaweed Assemblages-PAUL-CHAVEZ AND RIOSMENA-RODRIGUEZ 145

Multidisciplinary Symposium of the Santa Bay, B.C.S., Mexico. Page 115 in Pro­ Barbara Museum of Natural History, ceedings, XVth International Seaweed Santa Barbara, California. Symposium. Universidad Austral, Valdi­ NETO, J., and B. FARHAM. 1995. Structure via, . and seasonal variation of benthic algal RIOSMENA-RoDRIGUEZ, R., D. A SIQUEIROS­ communites on San Miguel Island BELTRONES, and G. ANAYA-REINA. 1998. (Azores). Phyco10gist 40: 26. New localities in seaweed distribution in NORRIs, J. N. 1972. Marine algae from the the Gulf of California. Rev. Invest. Cient. 1969 cruise of Makrele to the northern Ser. Cienc. Mar, Univ. Autonoma Baja part of the Gulf of California. Bol. Soc. Calif. Sur 8: 34-45. Bot. Mex. 32: 1-30. ROUND, G. J. 1964. Oceanographic aspects NORRIs, J. N., and K. E. BUCHER. 1976. New of the Gulf of California. Am. Assoc. Pet. records of marine algae from the 1974 Geol. Mem. 3: 30-58. R/V Dophin cruise to the Gulf of Califor­ SANTELICES, B. 1990. Patterns ofreproduction nia. Smithson. Contrib. Bot. 34: 1-22. and recruitment in seaweeds. Oceanogr. PIELOU, J. 1981. Biogeography. Wiley & Mar. Biol. Annu. Rev. 28:177-276. Sons, New York. ---. 1992. Marine phytogeography of REYES-BoNILLA, H., R. RIOSMENA- the Juan Fernandez Archipelago: A new RODRIGUEZ, and M. S. FOSTER. 1997. Her­ assessment. Pac. Sci. 46: 438-452. matypic corals associated with rhodolith SANTELICES, B., and I. A ABBOTT. 1987. beds in the Gulf of California, Mexico. Geographic and marine isolation: An Pac. Sci. 51: 328-337. assessment of the marine algae of Easter RIOSMENA-RoDRIGUEZ, R. 1996. Morfo10gia Island. Pac. Sci. 41 : 1-20. funcional de mantos de rodo1itos en el SEDESOL. 1994. Informe de 1a situacion Golfo de California, Mexico. Technical general en materia de equilibrio ecologico Report from Universidad Autonoma de y proteccion al ambiente 1993-1994. Baja California Sur-Comision Nacional Informe de la Secretaria de Desarrollo para el Uso y Conocimiento de la Bio­ Social, Mexico. diversidad. SETCHELL, W. A, and N. L. GARDNER. 1924. RIOSMENA-RoDRIGUEZ, R., and L. PAUL­ Marine algae from the Gulf of California. CRAVEZ. 1997. Sistematica y biogeografia Proc. Calif. Acad. Sci. 12: 695-949. de las macroalgas de la Bahia de La Paz, SILVA, P. C., R. A RASMUSSEN, H. KRAuss, B.C.S., Mexico. Pages 59-82 in J. Urban and P. AVILA. 1996. Marine flora ofRocas and M. Ramirez-Rodriguez, La Bahia de A1ijos. Pages 227-236 in R. W. Scmieder, la Paz: Investigacion y conservacion. Uni­ ed. Rocas Alijos. Kluwer Academic Pub­ versidad Autonoma de Baja California lishers, Dordrecht, The Netherlands. Sur-Centro Interdisciplinario de Ciencias SMITH, C. M. 1992. Diversity in intertidial Marinas and Scripps Institution of habitats: An assessment of the marine al­ Oceanography. gae of select high islands in the Hawaiian RIOSMENA-RoDRIGUEZ, R., and D. A Archipelago. Pac. Sci. 46: 466-479. SIQUEIROS-BELTRONES. 1994. Estado actual STEWART, J. G., and J. R. STEWART. 1984. y perspectivas del Herbario Ficologico de Marine algae of Guadalupe Island, Mex­ la Universidad Autonoma de Baja Cali- ico, including a check list. Cienc. Mar. 10 . fornia Sur. Rev: Invest Cient.Ser: Cien1:. (2): 129.::.14T .- Mar, Univ. Autonoma Baja Calif. Sur STODDART, D. R. 1992. Biogeography of the 4: 37-45. tropical Pacific Ocean. Pac. Sci. 46: 276­ RIOSMENA-RoDRIGUEZ, R., E. O. RODRIGUEZ­ 293. MORALES, and D. A SIQUEIROS­ VILLA, L. G. 1988. Islas del Golfo de Cali­ BELTRONES. 1995. Seasonal and biogeo­ fornia. Universidad Nacional Autonoma graphical trends of seaweeds from La Paz de Mexico, Mexico. 146 PACIFIC SCIENCE, Volume 54, April 2000

APPENDIX Family Ralfsiaceae SYSTEMATIC LIST OF SEAWEEDS OF THE ESpiRITU Ralfsia cali/ornica Setchell & Gardner SANTo-LA PARTIDA COMPLEX R. confusa Hollenberg Order Fucales Division Cholorophyta Family Sargassaceae Class Sargassum horridum Setchell & Gardner Order Bryopsidales S. lapazeanum Setchell & Gardner Family Bryopsidaceae Order Scytosiphonales Bryopsis pennatula J. Agardh. Family Chnoosporaceae Family Caulerpaceae Chnoospora minima (Hering) Papenfuss Caulerpa racemosa (Forskal) J. Agardh. Family Scytosiphonaceae C. sertularioides (Gmelin) Howe Hydroclathrus clathratus (Bory) Howe C. vanbosseae Setchell & Gardner Colpomenia sinuosa (Martens ex Roth) Derbes Family Codiaceae & Solie Codium cuneatum Setchell & Gardner C. tuberculata Saunders C. setchellii Gardner Rosenvingea cf. intrincata (J. Agardh) C. simulans Setchell & Gardner Boergensen Family Udoteaceae Order Sphacelariales Halimeda discoidea Decaisne Family Sphacelariaceae Order Sphacelaria brevicorne Setchell & Gardner Family Cladophoraceae S. rigidula Kiitzing Cladophora colombiana Collins Division Rhodophyta C. hesperia Setchell & Gardner Class Rhodophyceae C. microcladioides Collins Order Ahnfeltiales Lola lubrica (Setchell & Gardner) Hamel & Family Ahnfeltiaceae Hamel Ahnfelthia plicata (Hudson) Fries Rhizoclonium riparium (Roth) Harvey Order Bangiales Family Family Bangiaceae versluysii Weber-vanBosse Bangia atropurpurea (Roth) C. Agardh verticil/ata (Kiitzing) Boergensen Porphyra pendula Dawson Family Valoniaceae P. thuretii Dawson cladophoracea Martens Order Bonnemaisonales V pachynema (Martens) Boergensen Family Bonnemaisoniaceae Order Dasycladales Asparagopsis taxi/ormis (Delile) Trevisan Family Dasycladaceae Order Ceramiales Acetabularia calyculus Quoy & Gaimard Family Ceramiaceae Order Ulvales Antithamnion sublittorale Setchell & Gardner Family Ulvaceae Antithamnionella breviramosa (Dawson) Enteromorpha clathrata (Roth) Greville Womersley & Bailey E. compressa (Roth) Greville Centroceras clavulatum (c. Agardh) Montagne E. intestinalis (Roth) Greville Ceramiun caudatum Setchell & Gardner E. ramulosa var. acanthophora (Kiitzing) C. clarionense Setchell & Gardner Chapman C. equisetoides Dawson Viva dactyli/era Setchell & Gardner C. fimbriatum Setchell & Gardner U. lactuca Linnaeus C. flaccidum Ardissone U. lobata (Kiitzing) Setchell & Gardner C. horridum Setchell & Gardner Division Phaeophyta C. paniculatum Okamura Class Phaeophyceae C. procumbens Setchell & Gardner Order Dictyotales Digenia simplex (Wulfen) C. Agardh Family Dictyotaceae Griffithsia pacifica Kylin Dictyota crenulata J. Agardh Spyridiafilamentosa (Wulfen) Harvey D. dichotoma (Hudson) Lamouroux Family Dasyaceae -- D./labellata (Collins) Setchell&Gardner­ Dasya baillouviana (Gmelin) Montagne D. johnstonii Setchell & Gardner D. sinicola (Setchell & Gardner) Dawson D. volubilis Kiitzing sensu Vikers Heterosiphonia crispella (c. Agardh) Wynne Padina concrescens Thivy Taenioma perpusillum J. Agardh Padina mexicana Dawson Family Delesseriaceae Order Ectocarpales Myriogramme caespitosa Dawson Family Ectocarpaceae Family Rhodomelaceae Ectocarpus acutus Setchell & Gardner Chondria cali/ornica (Collins) Kylin E. bryantii Setchell & Gardner Herposiphonia spinosa Dawson E. gonodioides Setchell & Gardner H. secunda f. tene/la (C. Agardh) Wynne Trends in Seaweed Assemblages-PAUL-CHAVEZ AND RIOSMENA-RODRIGUEZ 147

Laurencia glandulifera (Kiitzing) Kiitzing Family Halymeniaceae L. johnstonii Setchell & Gardner Cryptonemia guaymanensis Dawson L. pacifica Kylin Grauteloupia dactylifera Dawson L. papillosa var. pacifica (c. Agardh) GreviIIe Halymenia abyssicola Dawson Polysiphonia decussata Hollenberg H templetonii (Setchell & Gardner) Abbott P. simplex Hollenberg Prionitis abbreviata Dawson Veleroa subulata Dawson Family Hypneaceae Order Corallinales Hypnea cervicornis J. Agardh Family Corallinaceae H valentiae (Turner) Montagne Amphiroa beauvoisii Lamouroux Family Nemastomataceae A. misakiensis Yendo Predaea masonii (Setchell & Gardner) J. De A. rigida Lamouroux Toni A. vanbosseae Lemoine Family Peyssonneliaceae Corallina vancouverensis Yendo Peyssonnelia rubra (GreviIIe) J. Agardh Heteroderma gibbsii Dawson Family Phylloporaceae Jania adhaerens Lamouroux Ahnfeltiopsis gigartinoides (J. Agardh) Silva & J longiartha Dawson DeCew Lithophyllum decipiens Foslie Family Wurdemanniaceae L. hancockii Dawson Wurdemannia miniata (Draparnaud) Feldmann L. imitans Foslie & Hamel L. margaritae (Hariot) Heydrich Order Gracilariales L. sonorensis Dawson Family Gracilariaceae Neogoniolithon trichotomun Setchell & Mason Graci/aria crispata Setchell & Gardner Order Erytropeltidales G. pachydermatica Setchell & Gardner Family Erytropeltidaceae G. spinigera Dawson Erytrotrichia carnea (Dillwyn) J. Agardh G. textorii (Suringar) J. Agardh Order Gelidiales Order Nemaliales Family Gelidiaceae Family Galaxauraceae Gelidium johnstonii Setchell & Gardner Galaxaura arborea Kjellman Pterocladiella capillacea (Bornet & Thuret) Liagora californica Zeh Santelices & Hommersan Tricheogleocarpa oblongata (Ellis & Solander) Family Gelidiellaceae Lamouroux Gelidiella acerosa (Forskal) J. Feldmann & Order Rhodymeniales Hamel Family Champiaceae Order Gigartinales Champia parvula (C. Agardh) Harvey