HABITAT MATTERS FOR INORGANIC CARBON ACQUISITION IN 38 SPECIES OF RED MACROALGAE (RHODOPHYTA) FROM PUGET SOUND,WASHINGTON, USA1

Measurements of pH drift were used to assess the ability of 38 red algal seaweeds to use bicarbonate and to deplete the dissolved inorganic carbon pool (DIC) from seawater medium. Subtidal algae were typically restricted to the use of DIC in the form of dissolved CO₂, reducing the initial DIC by only 9%. Intertidal species used both dissolved CO₂ and bicarbonate and reduced initial DIC by as much as 70%. DIC reductions and pH compensation points for the intertidal species tested were strongly correlated with their vertical zonation on the rocky shoreline (analysis of variance). DIC acquisition efficiency increased with tidal height, but species from the upper edge of the intertidal demonstrated a reversal of this trend. This general pattern associated with tidal height was observed not only among intertidal red algae in general, but also among four species of the genus Porphyra (P. torta V. Krishnamurthy, P. papenfussii Krishnamurthy, P. perforata J. Agardh, P. fucicola Krishnamurthy) and among four populations of the broadly distributed species Mastocarpus papillatus (C. Agardh). The Mastocarpus observations suggest either that individuals of this species may be able to express alternate strategies for carbon acquisition or that intertidal height may select for survivorship of genotypes with different carbon acquisition strategies. Taken together, these data suggest that the carbon acquisition strategy of intertidal red algae may be an important physiological set of adaptations that is under active evolutionary selection. These physiological differences were not related to phylogeny, tested as membership in red algal families and orders.     

Alternate life history phases of a common seaweed have distinct microbial surface communities

Macroalgal life histories are complex, often involving the alternation of distinct free‐living life history phases that differ in morphology, longevity and ploidy. The surfaces of marine macroalgae support diverse microbial biofilms, yet the degree of microbial variation between alternate phases is unknown. We quantified bacterial (16S rRNA gene) and microeukaryote (18S rRNA gene) communities on the surface of the common intertidal seaweed, Mastocarpus spp., which alternates between gametophyte (foliose, haploid) and sporophyte (encrusting, diploid) life history phases. A large portion (97%) of bacterial taxa on the surface Mastocarpus was also present in samples from the environment, indicating that macroalgal surface communities are largely assembled from the surrounding seawater. Still, changes in the relative abundance of bacterial taxa result in significantly different communities on alternate Mastocarpus life history phases, rocky substrate and seawater at all intertidal elevations. For microeukaryote assemblages, only high intertidal samples had significant differences between life history phases although sporophytes were not different from the rocky substrate at this elevation; gametophytes and sporophytes did not differ in microeukaryote communities in the mid and low zones. By sequencing three host genes, we identified three cryptic species of Mastocarpus in our data set, which co‐occur in the mid‐to‐low intertidal zone. In these samples, M. alaskensis sporophytes harboured distinct bacterial communities compared to M. agardhii and M. intermedius sporophytes, which were not distinguishable. Conversely, microeukaryote communities did not differ among species.     

GEOGRAPHICAL CORRELATION OF MORPHOLOGICAL VARIATION IN SILVETIA COMPRESSA (FUCACEAE,FUCALES, PHAEOPHYCEAE)

Silvetia compressa ( J. Agardh) Serrão et al. is a common member of the upper intertidal fucoid community on the Pacific coast of America from Humboldt County, California, to Punta Baja, Baja California, Mexico. A relatively narrow range of morphological variability is exhibited by most mainland populations, regardless of latitude, but some mainland populations and all insular populations participate in a complex pattern that we have attempted to analyze. A few populations on the Monterey Peninsula in which the fronds are atypically delicate were described by Setchell & Gardner as f. gracilis, to which was assigned a population from Santa Catalina Island. After comparing populations from various parts of the range of the species, including all of the Channel Islands, we conclude that two subspecies may be recognized. In subsp. compressa, which includes f. gracilis as a growth form and occurs chiefly on the mainland, the frond is robust with long tapered receptacles. In the variant subspecies, which is chiefly insular but also occurs on the coast of northern Baja California, the typical frond has slender axes as in f. gracilis, but is more densely branched and has short ellipsoidal receptacles. Comparison of nucleotide sequences from the ITS regions of rDNA revealed an identical pattern for subsp. compressa from Baja California and central California, including populations assignable to f. gracilis. By contrast, the pattern for the variant subspecies differed by 2 bp (0.3%) from that of subsp. compressa.     

18S‐Based Taxonomy and Intraspecific Its Sequence Variation in the Marine Fungal Endosymbiont Haloguignardia Irritans Infecting Cystoseira Osmundacea Along the Californian Coast

The marine ascomycete genus Haloguignardia occurs endophytically in members of the marine brown algal family Sargassaceae globally. This example of endosymbiosis has been morphologically described: the fungal component internally infects the algal host resulting in prolific cell growth, forming galls composed chiefly of host algal cells but containing fungal reproductive structures and vegetative hyphae. H. irritans induces the formation of galls in the brown algae Cystoseira osmundacea and Halidrys dioica along the Pacific coast from Oregon to Baja California, Mexico. Using culture‐independent molecular techniques, I sequenced the 18S rDNA gene region for H. irritans and generated a 18S‐based taxonomy consistent with the current taxonomy for this morphological species. In order to study intraspecific genetic variation in H. irritans, I have sequenced the ITS rDNA (ITS 1, 2 and the 5.8 s) regions for five separate gall‐tissue samples from Santa Rosa Island in southern California and for five samples from Monterey and Carmel in central California. Intraspecific DNA sequence variation in the ITS regions of H. irritans reveals consistent sequence divergence between sites sampled. The fungal ITS regions for H. irritans total 613 bp in length and contain 40 synapomorphic characters for a total of 6.5% variation in informative loci between southern and central Californian sites. This value is similar to those found for the ITS and other gene regions previously used by researchers investigating species boundaries at the intraspecific level in symbiotic, terrestrial fungi. In addition to ITS 1, 2 and the 5.8 s gene regions, I am currently using the 5’ end of the EF1a coding region to construct intraspecific genealogies for H. irritans. By comparing these genealogies to each other and to the geographic distribution of samples, I aim to determine if more than one genetic species is present within the morphological species H. irritans.     

DNA BARCODING IS A POWERFUL TOOL TO UNCOVER ALGAL DIVERSITY: A CASE STUDY OF THE PHYLLOPHORACEAE (GIGARTINALES,RHODOPHYTA) IN THE CANADIAN FLORA1

Previous studies have established that the 5′ end of the mitochondrial gene COI (cytochrome oxidase subunit I) is useful for rapid and reliable identification of red algal species and have demonstrated that our understanding of red algal biodiversity and biogeography is fragmentary. In this context, we are completing a thorough sampling along the Canadian coast and using the DNA barcode for the assignment of collections to genetic species to explore algal diversity in the Canadian flora. In the present study, we provide results regarding diversity of members of the red algal family Phyllophoraceae. We have analyzed 354 individuals from the Arctic, Atlantic, and Pacific coasts of Canada, as well as 26 specimens from the USA, Europe, and Australia, resolving 29 species based on the analyses of the DNA barcode. Twenty‐three of these genetic species were present in Canada where only 18 species are currently recognized, including Ceratocolax hartzii Rosenv., which was in the same genetic species group as its host Coccotylus truncatus (Pall.) M. J. Wynne et N. J. Heine and is thus transferred to Coccotylus, C. hartzii (Rosenv.) comb. nov., but retained as a distinct species owing to its unique habit and phenology. Our results revealed the presence of cryptic diversity within the genera Coccotylus, Mastocarpus, Ozophora, and Stenogramme, for which we resurrect Coccotylus brodiei (Turner) Kütz. and describe Mastocarpus pachenicus sp. nov., Ozophora lanceolata sp. nov., and Stenogramme bamfieldiensis sp. nov., leaving a multitude of unnamed Mastocarpus spp. in need of further taxonomic study. In addition, we report range extensions into British Columbia of Besa papillaeformis Setch., previously known only from its type and nearby localities in California; Gymnogongrus crenulatus (Turner) J. Agardh, recorded only from the Atlantic; and Stenogramme cf. rhodymenioides Joly et Alveal, previously only known from South America. Finally, the phylogenetic affinities of the Canadian species of Phyllophoraceae characterized in this study were investigated using LSU rDNA, RUBISCO LSU (rbcL), and combined analyses.     

EFFECT OF HIGH IRRADIANCE ON RECRUITMENT OF THE GIANT KELP MACROCYSTIS (PHAEOPHYTA) IN SHALLOW WATER1

Laboratory and field experiments were done hi Still-water Cove, Carmel Bay, California, and Monterey Harbor, California, to determine the effect of photosynthetically active radiation (PAR) on the shallow (upper) limit of giant kelp, Macrocystis pyrifera (L.) C. Agardh. At shallow depths, M. pyrifera did not recruit or grow to macroscopic size from gametophytes or embryonic sporophytes transplanted to vertical buoy lines; sharp decreases in PAR with depth coincided with observed recruitment and sporophyte distributions. Shade manipulations indicated that settlement of M. pyrifera zoospores was decreased, but not prohibited, by high PAR. Postsettlement stages (gametophytes and embryonic sporophytes), however, survived only under shade. These results suggest that high PAR can inhibit the recruitment of M. pyrifera to shallow water by killing its postsettlement stages; whether or not ultraviolet (UV) radiation also inhibits recruitment was not tested. In either case, however, it appears that high irradiance (PAR and/or UV) regulates the shallow limit of M. pyrifera prior to temperature and desiccation stresses inherent to intertidal regions. In an additional experiment, recruitment or growth of transplanted gametophytes or embryonic sporophytes of Macrocystis integrifolia Bory also did not occur at shallow depths, suggesting that this shallow water species accesses high irradiance regions via a method other than sexual reproduction.     

Morphological and molecular differentiation of smooth‐hound sharks (Genus Mustelus,Family Triakidae) from the Gulf of California

The genus Mustelus is the most species‐rich of the widespread family Triakidae whereby its taxonomy and systematics have been historically challenging. They represent a significant fraction of the shark catches of small‐scale fisheries in the Gulf of California. In order to provide information useful for their management and conservation, the morphological and genetic distinction of the four species found in the northern Gulf of California (M. albipinnis, M. californicus, M. henlei and M. lunulatus) were analyzed. Discriminant analysis of 10 morphometric variables placed each species in a distinct and significantly different region of multivariate morpho‐space. The variables contributing most to their distinction were inter‐nostril width, mouth length, upper and lower labial furrow length, and mouth width. Restriction fragment length polymorphisms (PCR‐RFLP) of the nuclear ITS2 ribosomal DNA (rDNA) confirmed that each species represents a genetically cohesive and independent evolutionary lineage. In spite of the difficulty in differentiating these Mustelus species, a few cephalic measurements are useful to separate them. A PCR‐RFLP assay (using RsaI and MspI on ITS2 rDNA amplicons) is also proposed for the molecular differentiation of these commercially harvested smooth‐hound sharks, constituting the first molecular marker available for their identification. These data provide morphological and genetic tools that can be used to improve their management and conservation.     

Phylogeographic patterns of a lower intertidal isopod in the Gulf of California and the Caribbean and comparison with other intertidal isopods

A growing body of knowledge on the diversity and evolution of intertidal isopods across different regions worldwide has enhanced our understanding on biological diversification at the poorly studied, yet vast, sea–land interface. High genetic divergences among numerous allopatric lineages have been identified within presumed single broadly distributed species. Excirolana mayana is an intertidal isopod that is commonly found in sandy beaches throughout the Gulf of California. Its distribution in the Pacific extends from this basin to Colombia and in the Atlantic from Florida to Venezuela. Despite its broad distribution and ecological importance, its evolutionary history has been largely neglected. Herein, we examined phylogeographic patterns of E. mayana in the Gulf of California and the Caribbean, based on maximum‐likelihood and Bayesian phylogenetic analyses of DNA sequences from four mitochondrial genes (16S rDNA, 12S rDNA, cytochrome oxidase I gene, and cytochrome b gene). We compared the phylogeographic patterns of E. mayana with those of the coastal isopods Ligia and Excirolana braziliensis (Gulf of California and Caribbean) and Tylos (Gulf of California). We found highly divergent lineages in both, the Gulf of California and Caribbean, suggesting the presence of multiple species. We identified two instances of Atlantic–Pacific divergences. Some geographical structuring among the major clades found in the Caribbean is observed. Haplotypes from the Gulf of California form a monophyletic group sister to a lineage found in Venezuela. Phylogeographic patterns of E. mayana in the Gulf of California differ from those observed in Ligia and Tylos in this region. Nonetheless, several clades of E. mayana have similar distributions to clades of these two other isopod taxa. The high levels of cryptic diversity detected in E. mayana also pose challenges for the conservation of this isopod and its fragile environment, the sandy shores.     

CHARACTERIZATION OF MARTENSIA (DELESSERIACEAE,RHODOPHYTA) BASED ON A MORPHOLOGICAL AND MOLECULAR STUDY OF THE TYPE SPECIES,M. ELEGANS,AND M. NATALENSIS SP. NOV. FROM SOUTH AFRICA1

An examination of a series of collections from the coast of Natal, South Africa, has revealed the presence of two species of Martensia C. Hering nom. cons: M. elegans C. Hering 1841, the type species, and an undescribed species, M. natalensis sp. nov. The two are similar in gross morphology, with both having the network arranged in a single band, and with reproductive thalli of M. elegans usually larger and more robust than those of M. natalensis. Molecular studies based on rbcL sequence analyses place the two in separate, strongly supported clades. The first assemblage occurs primarily in the Indo‐West Pacific Ocean, and the second is widely distributed in tropical and warm‐temperate waters. Criteria that have been used in the past for separating the two, namely, the number and shape of the blades, the presence of a single‐ versus a multiple‐banded network, and blade margins entire or toothed, were determined to be unreliable. Although the examination of additional species is required, the morphology and position of procarps and cystocarps, whether at or near the corners of the longitudinal lamellae and the cross‐connecting strands or along the lobed, membranous edges of the longitudinal lamellae or on the thallus margins, may prove to be diagnostic at the subgenus level. We recognize subg. Martensia, including the type of Martensia: M. elegans and subg. Mesotrema (J. Agardh) De Toni based on Martensia pavonia (J. Agardh) J. Agardh.     

AN EXAMINATION OF PACHYMENIA AND AEODES (HALYMENIACEAE,RHODOPHYTA) IN NEW ZEALAND AND THE TRANSFER OF TWO SPECIES OF AEODES IN SOUTH AFRICA TO PACHYMENIA1

A phylogenetic study was conducted of species of Halymeniaceae from New Zealand presently placed in Aeodes or Pachymenia, based on maximum‐likelihood (ML), maximum‐parsimony (MP), and Bayesian analyses of rbcL and nuclear internal transcribed spacer (ITS) rDNA sequences. We used molecular and morphological data in combination with exhaustive sampling of herbarium collections to clarify the taxonomy and distributions of New Zealand members of Pachymenia and Aeodes. Our study confirms the presence of three erect species of Pachymenia on the New Zealand mainland, and we resurrect the name Pachymenia dichotoma J. Agardh for the widely distributed, southernmost species. Species of Aeodes from South Africa are shown to be closely related to Pachymenia carnosa (J. Agardh) J. Agardh, the type species of Pachymenia, and are accordingly transferred to Pachymenia.     

TAXONOMIC REVISION OF SARGASSUM SPECIES (FUCALES,PHAEOPHYCEAE) FROM NEW CALEDONIA BASED ON MORPHOLOGICAL AND MOLECULAR ANALYSES1

Sargassum C. Agardh (1820) is a taxonomically difficult genus distributed worldwide and reported as the most species‐rich genus of the Fucales. It is especially abundant in the Pacific where decreasing species richness is reported to occur from west to east. New Caledonia has been recognized as one of the hotspots of Sargassum diversity; however, species lists available for this region are old and incomplete and have not yet been updated with regard to the latest taxonomic revisions published. This study aimed at revising Sargassum diversity in New Caledonia and to assess its geographic affinities with neighboring Pacific regions. We used combined morphological and DNA analyses on new collections and examined numerous type specimens. Although 45 taxa have been listed in the literature, most of them have been either transferred to synonymy since or misidentified, and in this study, only 12 taxa were recognized as occurring in New Caledonia. They belong to the subgenus Sargassum sect. Binderianae (Grunow) Mattio et Payri (2), sect. Ilicifoliae (J. Agardh) Mattio et Payri (2), sect. Polycystae Mattio et Payri. (1), sect. Sargassum (4), sect. Zygocarpicae (J. Agardh) Setch. (2), and subgenus Phyllotrichia (Aresh.) J. Agardh (1). New Caledonian Sargassum flora appeared as the second richest in the region after the Pacific coast of Australia, with which it has shown high similarity, and shared species with all neighboring regions. One species, S. turbinarioides Grunow, is considered as endemic to New Caledonia. The low genetic diversity detected among several polymorphic species belonging to sect. Sargassum is also discussed.     

Characterization of the edible red alga Meristotheca papulosa (Solieriaceae, Gigartinales) from Japan

The vegetative and reproductive morphology of the edible red alga Meristotheca papulosa (Montagne) J. Agardh (Solieriaceae) was reexamined based on material collected from various localities in Japan. Although the habit of the blades is variable according to the length and width of the axes, the frequency of branching and the abundance of proliferations, rbcL sequence analyses indicate their conspecificity. M. papulosa displays four distinctive reproductive features (presence of an auxiliary cell complex, occurrence of cystocarps on marginal proliferations and the blade surface (although very rare) in addition to the margins of axes, frequent production of spinose outgrowths on the pericarp and tetrasporangial initials typically basally attached to their parental cells) that have not been reported for M. papulosa from other areas. Although these features might warrant recognition of the Japanese entity as a separate species, a better understanding of their possible taxonomic value requires comparisons with M. papulosa from other geographic regions, including the type locality.     

MOLECULAR PHYLOGENY OF GRACILARIA SPECIES INFERRED FROM MOLECULAR MARKERS BELONGING TO THREE DIFFERENT GENOMES1

The nucleotide sequence data of molecular markers 18S rRNA, RUBISCO spacer, and cox2‐3 intergenic spacer were integrated to infer the phylogeny of Gracilaria species, collected from the western coast of India, reducing the possibility of misidentification and providing greater phylogenetic resolution. A phylogenetic tree was constructed using cox2‐3 and RUBISCO spacer sequences, exhibiting the same clustering but differing slightly from that of the rRNA‐based phylogenetic tree. The phylogeny inferred from the combined data set confers an analogous pattern of clustering, compared with those of trees constructed from individual data sets. The combined data set resulted in a phylogeny with better resolution, which supported the clade with higher consistency index, retention index, and bootstrap values. It was observed that Gracilaria foliifera (Forssk.) Børgesen is closer to G. corticata (J. Agardh) J. Agardh varieties, while G. salicornia (C. Agardh) E. Y. Dawson and G. fergusonii J. Agardh both originated from the same clade. The position of G. textorii (Suringar) De Toni faltered and toppled between G. salicornia and G. dura (C. Agardh) J. Agardh; however, G. gracilis (Stackh.) M. Steentoft, L. M. Irvine et W. F. Farnham was evidently distant from the rest of the species.     

GENETIC VARIATION AMONG STRAINS OF PSEUDOPFIESTERIA SHUMWAYAE AND PFIESTERIA PISCICIDA (DINOPHYCEAE)1

The putatively toxic dinoflagellates Pseudopfiesteria shumwayae (Glasgow et J. M. Burkh.) Litaker, Steid., P. L. Mason, Shields et P. A. Tester and Pfiesteria piscicida Steid. et J. M. Burkh. have been implicated in massive fish kills and of having negative impacts on human health along the mid‐Atlantic seaboard of the USA. Considerable debate still remains as to the mechanisms responsible for fish mortality (toxicity vs. micropredation) caused by these dinoflagellates. Genetic differences among these cultures have not been adequately investigated and may account for or correlate with phenotypic variability among strains within each species. Genetic variation among strains of Ps. shumwayae and P. piscicida was examined by PCR–RFLP analysis using cultures obtained from the Provasoli‐Guillard National Center for Culture of Marine Phytoplankton (CCMP), as well as those from our own and other colleagues’ collection efforts. Examination of restriction digest banding profiles for 22 strains of Ps. shumwayae revealed the presence of 10 polymorphic restriction endonuclease sites within the first and second internal transcribed spacers (ITS1 and ITS2) and the 5.8S gene of the rDNA complex, and the cytochrome oxidase subunit I (COI) gene. Three compound genotypes were represented within the 22 Ps. shumwayae strains. Conversely, PCR–RFLP examination of 14 strains of P. piscicida at the same ITS1, 5.8S, and ITS2 regions revealed only one variable restriction endonuclease site, located in the ITS1 region. In addition, a dinoflagellate culture listed as P. piscicida (CCMP 1928) and analyzed as part of this study was identified as closely related to Luciella masanensis P. L. Mason, H. J. Jeong, Litaker, Reece et Steid.     

Delineation of Two Sibling Red Algal Species,Gracilaria Gracilis and Gracilaria Dura (Gracilariales,Rhodophyta), Using Multiple DNA Markers: Resurrection of the Species G. Dura Previously Described in the Northern Atlantic 200 Years Ago1

Molecular markers belonging to the three different genomes, mitochondrial (cox2‐cox3 spacer), plastid (rbcL), and nuclear (internal transcribed spacer [ITS] 2 region), were used to compare samples of the two morphologically related species Gracilaria gracilis (Stackh.) Steentoft, L. M. Irvine et Farnham and G. dura (C. Agardh) J. Agardh collected along Atlantic coasts. In northern Europe, the distinction between these two species is ambiguous, and they are currently recognized under the single name of G. gracilis. The low but congruent patterns of genetic divergence observed for markers of the three genomic compartments highly suggest that these two taxa correspond effectively to two different genetic entities as previously described 200 years ago, based on morphological traits. However, thanks to the combination of different DNA markers, occurrence of “incongruent” cytotypes (i.e., mitotypes of G. dura associated with chlorotypes of G. gracilis) in individuals collected from Brittany, suggests interspecific hybridization between the two sibling species studied.     

Dispersal and recruitment of a canopy-forming intertidal alga: the relative roles of propagule availability and post-settlement processes

The daily settlement of eggs and zygotes of the monoecious brown alga Pelvetia compressa (J. Agardh) De Toni was measured on artificial substrata in areas inside and outside patches of adults in the high intertidal zone of central California. Settlement was generally 1–2 orders of magnitude higher under the adult canopy. This pattern seems to be due to the synchronous release of gametes during the daytime low tide. The release of gametes also appears periodic over longer time scales (e.g., 3- and 14-day cycles). In spite of the high availability of propagules under the adult canopy, juveniles were most abundant outside patches, where propagule availability was lower. In both areas, juveniles were disproportionately associated with patches of a red algal turf [primarily Endocladia muricata (Postels & Ruprecht) J. Agardh and Masticarpus papillata (C. Agardh) Kützing]. The turf, which is less common under the P. compressa canopy, may offer protection from dislodgment, grazing, and/or desiccation and thus facilitate recruitment at this site. Overall, post-settlement processes appear more important in determining population structure than does the availability of propagules in areas in and around patches of adults. However, the apparent small range of dispersal of P. compressa may make propagule availability an important limitation to the establishment of new populations and may restrict gene flow between populations. Received: 31 October 1997 / Accepted: 31 August 1998     

THERMAL ECOPHYSIOLOGY OF LAURENCIA PACIFICA AND LAURENCIA NIDIFICA (CERAMIALES,RHODOPHYTA) FROM TROPICAL AND WARM‐TEMPERATE REGIONS1

Laurencia is a globally distributed genus with about 80 species (order Ceramiales) that inhabit tropical, subtropical, and warm‐temperate regions of both sides of the Atlantic and Indo‐Pacific oceans. This study investigated how two species of Laurencia distributed in different thermal environments (California and Hawaii) varied in their photosynthetic responses to temperature. The thermal ecophysiology of both species was investigated at different temporal scales (short‐term responses and seasonal acclimatization) using oxygen evolution and pulse‐amplitude‐modulated (PAM) fluorometry. Our results indicated that seasonal acclimatization of both species of Laurencia influenced the short‐term photosynthetic response at both locations. Greater seasonal differences in the photosynthetic performance were observed for L. pacifica Kylin, which reflects the ability of this species to acclimatize to local environmental conditions characterized by short‐term fluctuations and a broader annual temperature range. Photosynthetic performance of L. nidifica J. Agardh was consistent with the less variable local environment (no short‐term fluctuations and a narrower temperature range). These results suggest that acclimatization to temperature variability in the environment can influence the degree of flexibility of physiological responses of species in this genus.