Vertical distribution of coralline algae in the rocky intertidal of northern Chile

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<ul><li><p>Hydrobiologia 260/261: 121-129, 1993.A. R. O. Chapman, M. T. Brown &amp; M. Lahaye (eds), Fourteenth International Seaweed Symposium. 1993 Kluwer Academic Publishers. Printed in Belgium.</p><p>121</p><p>Vertical distribution of coralline algae in the rocky intertidal ofnorthern Chile</p><p>Isabel Meneses C.Departamento de Biologia Marina, Universidad Cat6lica del Norte, Casilla 117, Coquimbo, Chile</p><p>Key words: Crustose corallines, vertical distribution, coralline taxa</p><p>Abstract</p><p>Studies on crustose corallines present in the intertidal region at three localities in northern Chile (30 S),show that these algae are well represented in exposed and protected sites, reaching up to 90% cover.Species composition differs between sites with the common occurrence of species or morphologicalvariants of Spongites and a single taxon attributed to Phymatolithon at the most exposed sites, and speciesof Lithophyllum and Titanoderma at more protected localities. The two Lithophyllum taxa recorded aredistinguished by the presence/absence of protuberances, cell size and degree of calcification, whileTitanoderma taxa are segregated by the thickness of the thallus, hypothallic and perithallic cell size andshape. Spongites taxa are distinguished on the basis of external morphology and anatomical features suchas cell size, degree of calcification and percentage of fusions between cells. The variability of thesefeatures within each species is still unknown thus, the taxa remain without specific epithet until furtherstudies. Examination of specific types recorded for nearby regions are also required in order to clarifythe taxonomy of the group in these coasts.</p><p>Introduction</p><p>Information about crustose coralline taxa forsouthern South America is restricted mainly tothe species records and descriptions based onmaterial collected by expeditions undertaken atthe beginning of the 1900s. These records includethe Antarctic Peninsula, subantarctic islands,Tierra del Fuego and Patagonia, Chilo6 andHuafo islands and the Juan Fernandez Archipel-ago (Foslie 1900, 1907a; Lemoine 1913, 1920).Foslie (1900, 1907) examined material collectedin Tierra del Fuego and Strait of Magellan de-scribing 5 species of Lithothamnion and 2 speciesof Lithophyllum. Lemoine (1913, 1920) describedin detail 4 species from Chiloe Island, one fromthe Juan Fernandez Archipelago and 3 species</p><p>from Tierra del Fuego and Patagonia. Lemoine(1920) also included 7 of Foslie's species, chang-ing Lithophyllum discoideum to her newly de-scribed genus Pseudolithophyllum. Foslie's collec-tion was later revised by Adey (1970) whochanged the generic epithet of at least 5 speciesfrom Tierra del Fuego. Finally, new changes atthe generic level have been done by Mendoza(1976a, 1976b) and Mendoza &amp; Cabioch (1984)while working on the distribution of crustose cor-allines from Tierra del Fuego. In addition to thesestudies on material from the southern tip of SouthAmerica and scanty records of crustose corallinetaxa further north (Foslie, 1906, 1907b; Heydrich,1901), no information is available for the rest ofthe Chilean coasts.</p><p>The generic concepts in coralline algae have</p></li><li><p>122</p><p>been exhaustively reexamined by several authors(for a review see Woelkerling, 1988) based uponthe revision of type specimens (Woelkerling,1983a, 1983b, 1985, 1986; Woelkerling &amp; Irvine,1986; Woelkerling et al. 1985; Penrose, 1991).These taxonomic reassessments resulted in sev-eral changes among the species described by pre-vious authors therefore leading to the necessity ofapplying a new systematical approach to the crus-tose corallines in those regions that have not beenpreviously studied.</p><p>Considering the state of the art in crustose cor-alline taxonomy and the lack of information forthese taxa along the Chilean coasts, this studyaims to describe the taxa present at three locali-ties of northern Chile and their distribution at theintertidal region.</p><p>Materials and methods</p><p>The three study sites are Totoralillo(30 6' S,71 24' W), Lagunillas (30 6' S,71 24' W) and Guanaquerillos (30 12' S,71 28' W), and all are located within a distanceof approximately 50 km from each other. Twosites were chosen in each of these localities(Figs 16-18). In each site, sampling was madealong two transects parallel to the shoreline.Cover percentage of taxa was estimated by thepoint interception method with a quadrat of50 cm2. Quadrats were placed every 1 or 2 malong the transects, and the distance betweenconsecutive quadrats depended on the length ofthe intertidal at each locality.</p><p>Crustose coralline material was separated inthe field on the basis of external features such ascolor, texture, and thickness. Small thallus pieceswere sampled at each station, labelled and carriedto the laboratory in plastic bags.</p><p>Thallus pieces were examined under a Nikon(model SMZ-10) dissecting microscope and frac-tured by hand. Pieces were mounted and glued oncylindrical bronze stubs and double coated withcarbon and gold. Observations and photographswere taken with a scanning electron microscopeJEOL T-300. Photographic film used wasT-MAX 100 ASA.</p><p>Results</p><p>Description of crustose coralline taxa recorded</p><p>Representatives of four genera of crustose coral-line algae Spongites Kiltzing, Lithophyllum Phil-ippi, Titanoderma Nageli and Phymatolithon Fos-lie are present in the rocky intertidal of the threelocalities examined. The genera have been distin-guished on the basis of the classification systemgiven by Woelkerling (1988). Spongites belongs tothe subfamily Mastophoroideae and is character-ized by having uniporate tetrasporangial concep-tacles (Fig. 1), an hypothallus consisting of one ormore cell layers (Fig. 3) parallel to the substratebut not coaxial, and a thallus mainly formed bya perithallus without pit-connections but with fu-sions connecting cells of adjacent filaments(Fig. 4). Either 5 species of Spongites or 5 mor-phological variants of one or two species of thisgenus occur in the region. These five taxa differ infeatures such as presence/absence of protuber-ances, percentage of fusions, cell and degree ofcalcification (Figs 4, 5 &amp; 6) among the perithalliccells. All specimens have a multistratified epith-allus with a subepithallic meristem (Fig. 2).Spongites is the only genus widespread among thestudy sites (Figs 16-18).</p><p>The genus Lithophyllum, which together withTitanoderma, belongs to the Lithophylloideae isrepresented by two species occurring only at To-toralillo (Fig. 16). Both species have an hypothal-lus reduced to one single basal layer of cells(Fig. 7), uniporate tetrasporangial conceptaclesand a well-developed perithallus in which no fu-sions are observed. Only secondary pit-connec-tions are detected in transverse sections of thethallus (Figs 8, 9). The two species of Lithophyl-lum not only differ in their external morphology,Lithophyllum sp. 1 has a thin crust with even sur-face and Lithophyllum sp. 2 has a thick thalluswith irregularities and protuberances in its sur-face, but also in their inner features. Perithalliccells of adjacent filaments in Lithophyllum sp. 1appear located at the same vertical level while thisis not evident in Lithophyllum sp. 2 (Figs 8, 9). Onthe other hand, Lithophyllum sp. 2 has larger per-</p></li><li><p>123</p><p>Figures 1-6. Spongites taxa. Figures 7-8. Lithophyllum spp.Fig. 1. Uniporate terrasporangial conceptacle. Fig. 2. Thallus section showing round-celled epithallus (e) and subepithallicmeristem (m). Fig. 3. Multistratified hypothallus (h). Fig. 4. Perithallus (p) in Spongites sp. with thin cell walls and fusions(arrowheads). Fig. 5. Perithallus (p) in Spongites sp. 3 with heavily calcified cell walls. Fig. 6. Perithallus (p) of vertically elon-gated cells in Spongites sp. 2. Fig. 7. Hypothallic (h) basal layer in Lithophyllum sp. 2. Fig. 8. Banded perithallus (p) with sec-ondary pit-connections (arrowheads).Fig. 1 scale = 50 Im, Figs. 2-4, 7, 8 scale = 10 pm, Figs. 5, 6 scale = 5 Jm.</p></li><li><p>124</p><p>Figures 9, 10. Lithophyllum spp. Figures 11-13. Titanoderma sp. Figures 14, 15. Phymatolithon sp.Fig. 9. Banded perithallus (p) showing abundant secondary pit-connections (arrowheads). Fig. 10. Thin cell-walled perithallus(p) and epithallus (e). Fig. 11. Palisade-like cells of hypothallus (h), with secondary pit-connections (arrowheads) in</p></li><li><p>125</p><p>TOTORALILLO</p><p>Titanodrrnma sp</p><p>Spongites sp3100 </p><p>_ _ Lithophyllum spl</p><p>_ _</p><p>Lithophyllum sp 2</p><p>Crustose corallines</p><p>-11 48CORALLINA SP</p><p>HILDENBRANDIA SP</p><p>PROFILE</p><p>0 2 4 6 8 10 12 14 16mSEA4-</p><p>0 2 4 6 8 io 12m</p><p>Fig. 16. Vertical distribution and abundance (expressed as cover percentage) of crustose coralline taxa in the locality of Totoralillo.Lower section shows non-crustose coralline taxa and total crustose coralline taxa, upper section shows crustose corallines sep-arated into taxa.</p><p>ithallic cells, less calcified cell walls and second-ary pit-connections are less frequent than in Li-thophyllum sp. 1 (Fig. 10).</p><p>The only species of Titanoderma was collectedat Totoralillo (Fig. 16), and is distinctive by anhypothallus of elongate, obliquely oriented, pali-sade-like cells (Fig. 11), perithallic cells of adja-cent filaments at the same vertical level (Fig. 12)joined by secondary pit-connections (Fig. 11) andan unistratified epithallus (Fig. 13).</p><p>The last taxon recorded is a species attributedto the genus Phymatolithon although further infor-mation is required to be certain of this identifica-tion. This species has multiporate tetrasporangialconceptacles (Fig. 14), a non-coaxial hypothallus(Fig. 15) and only occasional fusions present(Fig. 15) between cells of adjacent filaments.</p><p>Distribution and abundance of crustose corallinetaxa in each the localities studied</p><p>Totorallillo is the most protected amongst thesites studied and consists of a long and extendedintertidal region. Crustose corallines are presentall along the 16 and 13 m of the transects sampled(Fig. 16) at the two sites. In general, geniculatecorallines and Hildenbrandia sp. are the mostabundant taxa at this locality. Crustose corallinesnever reach abundances higher than 40% in thequadrats closest to the ocean, and include twospecies of Lithophyllum, one of Titanoderma andone of Spongites. These taxa occur in both siteswith Lithophyllum sp. 2 restricted to the high in-tertidal in site A and Spongites sp. 3 restricted tothe low intertidal in site B (Fig. 16).</p><p>O- 0-</p><p>GELIDIUM SP</p><p>perithallus (p). Fig. 12. Banded perithallus (p). Fig. 13. Unstratified epithallus (e). Fig. 14. Multiporate tetrasporangial concep-tacle (pores = p). Fig. 15. Multistratified hypothallus (h) with fusions (arrowheads).Figs 9-13 scale = 10 #m, Fig. 14 scale = 50 pm, Fig. 15 scale = 20 pm.</p><p>_ _ </p><p>v T </p><p>____ __I I</p><p>- - -</p></li><li><p>126</p><p>Lagunillas can be characterized as beingsemiexposed to wave action. Here, the intertidalregion is shorter extending for no longer than13 m. Different sites within the same locality arevariable in the distribution and composition ofcrustose corallines (Fig. 17). Only Spongites isrepresented in this locality. Crustose corallines asa group are more abundant here than in Totora-lillo, reaching up to 90% cover in site A. Twospecies of Spongites alternate between the sites.</p><p>Finally Guanaquerillos is an exposed localityin which the intertidal region is highly reduced(10 m in site A and 5 m in site B). Three taxa ofSpongites and one of Phymatolithon are the rep-resentatives of crustose corallines at this locality,where they reach up to 80% in cover. Phymatoli-thon sp. is restricted to a low percentage in coverin site B (Fig. 18).</p><p>Discussion</p><p>Clearly the crustose coralline entity until now re-ferred to as 'Lithothamnia' for the coasts of Chile</p><p>(Guiler, 1959; Stephenson &amp; Stephenson, 1972,Alveal &amp; Romo, 1977) is a complex assemblageof taxa with a high variability in its compositiondepending on the characteristics of each locality.Although representatives of this group occur inthe three sites studied, their patterns of distribu-tion and relative abundance vary between sites.Exposure to wave action seems to be a factorinfluencing the taxa composition and abundance.The Lithophylloideae (Lithophyllum and Titano-derma) are found in protected and flat areas suchas the intertidal of Totoralillo, while specimens ofSpongites and Phymatolithon appear in higherabundance and frequency in exposed or semi-exposed areas like Lagunillas and Guanaqueril-los. This taxa partitioning of the habitats has alsobeen observed in calcareous crustose algae fromTierra del Fuego (Mendoza, 1988). Mendoza(1988) points out that Clathromorphum obtectulum(Foslie) Adey and Hydrolithon falcklandicum(Foslie) Mendoza appear mainly in the low in-tertidal while Clathromorphum lemoineanum Men-doza et Cabioch and Hydrolithon consociatum(Foslie) Mendoza occur in the low subtidal.</p><p>LAGUNILLASJuveniles</p><p>Spongites sp3</p><p>_ -4 Spongites sp2Spongites spl</p><p>Crustose corallines</p><p>-W LESSONIA</p><p>4 CODIUMMONTEMARIA</p><p>PROFILE</p><p>12 10 8 6 4 2 Om 12 1 8 6 4 2 Om-SEA</p><p>Fig. 17. Vertical distribution and abundance (expressed as cover percentage) of crustose coralline taxa in the locality of Lagunillas.Lower section shows non-crustose coralline taxa and total crustose coralline taxa, upper section shows corallines separated intotaxa.</p><p>01% </p><p>__</p><p>L --0000Il</p><p>ANIft</p></li><li><p>GUANAQUERILLOSPhymatolithon sp</p><p>Spongites sp 5</p><p>Spongites sp4</p><p>Spongites spl</p><p>Crustose corallines</p><p>GELIDIUM14 _,</p><p>8 6 4 2 Om 4 3 2 1 Om</p><p>HI LDENBRANDIA</p><p>PROFILE</p><p>e SEA</p><p>Fig. 18. Vertical distribution and abundance (expressed as cover percentage of crustose coralline taxa in the locality of guanaque-rillos). Lower section shows non-crustose coralline taxa and total crustose coralline taxa, upper section shows crustose corallinesseparated into taxa.</p><p>Furthermore, crustose coralline taxa at Totora-lillo seem to have a relatively uniform distributionand similar abundances along the entire length ofthe transects. This could reflect the homogeneityof the habitat, a flat zone of small boulders withscattered areas of coarse sand along approxi-mately 20 m.</p><p>The genus Spongites is taxonomically complex,recently Hydrolithon Foslie (1909), PorolithonFoslie (1909) and Pseudolithophyllum sensu Adey(1970) were included under its circumscription(Penrose &amp; Woelkerling, 1988). This resolutionwas taken considering that trichocyte arrange-ment and occurrence, hypothallus structure (un-istratified versus multistratified) and cell size arecharacters too variable to distinguish among thesegenera. However, observations based on the tet-rasporangial conceptacle development of the typespecies of Hydrolithon, Porolithon and Spongites(Penrose &amp; Woelkerling, 1992) indicate that thefirst two genera share the presence at the porecanal of a ring of elongate cells oriented more orless perpendicularly to the roof surface, these cellsarise from filaments interspersed amongst spo-rangial initials and do not protrude into the canal.</p><p>In Spongites the ring of cells is oriented more orless parallel to the roof surface, protrudes into thecanal and arises from peripheral roof filaments(Penrose &amp; Woelkerling, 1992). These two pat-terns are considered to provide a basis for genericsegregation...</p></li></ul>

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