DOCSLIB.ORG

Laminariales)

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Laminariales) DYNAMICS OF CARBON ALLOCATION IN A DEEP WATER POPULATION OF THE DECIDUOUS KELP, Pleurophycus gardneri (LAMINARIALES) A thesis Presented to the F acuity of California State University at Monterey Bay through Moss Landing Marine Laboratories In Partial Fulfillment of the Requirements for the Degree Master of Science in Marine Science by Clare Margaret Dominik March 25, 2004 ABSTRACT Pleurophycus gardneri (Laminariales) is common in the low intertidal in the Pacific Northwest, but dominates many deep (30 to 40 m) reefs in central California. Seasonal dynamics of productivity and resource allocation of a deep-water population of this deciduous, stipitate kelp were studied to understand how blade abscission affects the annual carbon budget. Patterns of growth, metabolism, carbon storage and mobilization were measured monthly for one year relative to in situ light and temperature, and used to model the annual carbon budget. The carbon budget model was used to determine if blade abscission effectively reduced respiratory demand during winter when light availability was lowest. Blade growth occurred between February and July, followed by senescence and sloughing from August to December. Concentrations of laminaran and mannitol increased in the blades from the onset of sloughing until just prior to blade abscission (mid-December) suggesting translocation may have occurred from the blade to the stipe and holdfast. The initial model overestimated net production most probably because it failed to account for movement of the blade relative to the incident light. Sensitivity analysis resulted in the best fit when blades were assumed to utilize only 25 to 50% of ambient irradiance at 30m. The model indicated that blades could be retained over the winter assuming they received 25 to 50% of in situ irradiance. Thus, abscission was not necessary for metabolic survival and abscission may be related to other factors such as reduction in winter­ storm/surge induced damage/loss or enhanced spore dispersal through drift of abscised blades with sori. Keywords: Carbon budget, photosynthesis and abscission. 2 INTRODUCTION Autumnal leaf abscission has commonly been associated with conservation of energy in deciduous trees by synchronously senescing and dropping leaves. Large respiratory requirements of the leaves cannot be met during shortened winter photoperiods (Addicott 1982). Translocation of cellular material occurs from the leaves to the phloem during senescence (Pennell and Lamb 1997) prior to abscission for storage and possible utilization over the winter (Addicott 1982). Among most deciduous trees, cold temperatures and/or light (day-length) are the most influential cues for abscission. Light is also a common limiting factor for many plants in marine kelp dominated systems (Schiel and Foster 1986, Dean 1985). Canopy cover of Macrocystis pyrifera can limit light availability and growth of understory algae (Reed and Foster 1984, Wantanabe et al. 1992, Edwards 1998). Disturbance by large storms can increase light availability to under-story plants in shallow water by removing over-story layers (Graham 1997). These seasonal or episodic events can allow algae that would otherwise be excluded due to insufficient light, to establish and grow. In northern latitudes, kelps have a variety of physiological mechanisms that allow them to survive seasonally through alternating periods of nutrient limitation during the summer and light­ limitation in winter (Gagne et al. 1982). Laminaria solidungula utilized stored carbohydrates accumulated during summer to complete 90% of its annual linear blade growth during the virtual darkness of the Arctic winter (Dunton and Schell 1986, Chapman and Craigie 1977, 1978, Mann 1973 ). Summer accumulation of carbohydrates for use during winter requires periods of high summer irradiance combined with nutrient limitation that prevents growth. 3 Cellular photoacclimation increases photosynthetic efficiency and thus can contribute to survival when light availability is low. Algae from deep water may contain more accessory pigments, which harvest light more efficiently at low light intensities (Ramus 1983). Another characteristic includes thinner thalli compared to algae in shallow water, resulting in lower respiration rates that promotes survival in low light (Markager and Sand-Jensen 1992). Another potential way algae can survive the low light conditions of winter is to reduce total biomass and thus, respiratory demand. Abscission of reproductive tissues is common among brown algae, including Nereocystis sp., Fucus spp.. and Ascophyllum sp., and also possibly among A/aria sp., Lessoniopsis sp.. Pterogophora sp. (Addicott 1982). It is unclear whether Laminaria sinclarii truly abscises or whether the blade is removed by physical abrasion (Markham 1972). Pleurophycus gardneri (Laminariales) is a deciduous perennial (Germann 1986) or pseudoperennial (Sears and Wilce 1975) and is the only kelp known now to undergo synchronous defoliation of the vegetative (photosynthetic) blade each winter. Germann (1989) suggested abscission of the senescent blade may be more advantageous than its retention because the high photosynthetic efficiency and low respiration of the stipe and the holdfast may compensate for loss of greater photosynthetic surface area of the blade, which has large respiratory requirements. The perennial stipe and holdfast may also function as a reservoir for carbohydrates translocated from the blade before abscission. The distribution of Pleurophycus gardneri was originally reported to be from Montague Island, Alaska to Fort Bragg, California, in the low intertidal to upper subtidal (Abbott and Hollenberg 1976). Individuals are common in the northern part of the range but comparatively rare in the south. VanBlaricom et al. (1986) found low densities of P. gardneri (<1 individual -2) m at depths above 15m, and much higher densities (up to 10 plants m-2) in deep water off the 4 coast of Big Sur, California. Stands of plants with densities of 5 plants m-2 have recently been observed at depths between 27 and 34m in Carmel Bay, California (Spalding eta!. 2003). These observations prompted this investigation into the ability of a kelp previously thought restricted to intertidal regions, to flourish at 30m depth almost 500 km south of its originally reported southern limit. Many species ofLaminariales have been rigorously studied to examine the relationships between light availability (Luning 1979, Dunton 1985, Dunton and Jodwalis 1988, Dunton and Schell 1986), translocation and production of carbohydrates (Luning et a!. 1973, Chapman and Craigie 1978), nitrate concentrations and growth (Chapman et al. 1978, Germann et al. 1987). The objective of this study was to explore the dynamics of carbon assimilation and its utilization for growth by Pleurophycus gardneri in this deep water habitat. Physiological rate measurements, in situ growth studies and chemical analysis were used to construct a numerical carbon budget model. This model was used to explore 1) whether abscission is an effective mechanism for reducing whole plant respiratory demand and, 2) the length of time that perennial tissues can survive on storage carbohydrates alone during the winter. METHODS To create this model all inputs and outputs of the plants were quantified to establish net production with respect to carbon. Light was the major driver of the model, and Zimmerman et al. 0994) have shown that production estimates based on instantaneous irradiance measurements are more accurate than hours of daily irradiance saturated photosynthesis (HsAT) to model daily carbon gain by a plant. Instantaneous light measurements and photosynthetic production estimates yielded a d · · . gross pro uctmn estimate from winch losses (respiratiOn and sloughmg) were 5 subtracted. Chemical composition (carbohydrate and pigment concentrations) was determined to evaluate source/sink relationships among the four different tissue types of the plant. Plant size, 1 defined as total carbon (gC planf ) summed from each tissue type, and plant growth and/or sloughing were quantified and used to evaluate the models ability to predict changes in plant size as a function oflight availability. Carbon budget models of hypothetical plants retaining blades suggests what would happen to plant size if abscission did not occur. Study Site The study area was located in 30m of water at the East Pinnacles (36°33'35" N, 121°57'53" W), approximately 1.5 km offshore from Stillwater Cove, Carmel Bay, California. High relief granite pinnacles interspersed with large boulders and small sand channels characterized the area. Pinnacle tops above 20 m depth support a canopy ofMacrocystis pyrifera, which is thinned annually by winter storms. The stipitate kelps Pterygophora califomica, Eisenia arborea, and Pleurophycus gardneri were interspersed with giant kelp at 20 m but higher densities of P. gardneri were found in deeper water outside the giant kelp canopy. Fleshy red and geniculate coralline algae comprised a variably abundant algal turf underneath the stipitate kelps. Stipitate kelps outside the kelp canopy periodically lay flat and overlap one another when there is no surge or current (typically during summer months) providing shading and structure much like a sub-surface "canopy." Nongeniculate coralline algae, along with red and occasionally green encrusting algae, generally occupied the primary substrate interspersed with encrusting invertebrates (see also Spalding et al. 2003). Light Availability
Load more

Recommended publications
  • Molecular Investigation Reveals Epi/Endophytic Extrageneric Kelp (Laminariales, Phaeophyceae) Gametophytes Colonizing Lessoniopsis Littoralis Thalli
    Botanica Marina 48 (2005): 426–436 ᮊ 2005 by Walter de Gruyter • Berlin • New York. DOI 10.1515/BOT.2005.056 Molecular investigation reveals epi/endophytic extrageneric kelp (Laminariales, Phaeophyceae) gametophytes colonizing Lessoniopsis littoralis thalli Christopher E. Lanea,* and Gary W. Saunders tidal zones along the western Vancouver Island coast. Members of the Laminariales make up the majority of the Centre for Environmental and Molecular Algal Research, seaweed biomass in the intertidal zone of this region and University of New Brunswick, Fredericton, New their size and distinctive morphology have made them an Brunswick, E3B 6E1, Canada, e-mail: [email protected] extensively studied order of brown algae (Lane et al. in *Corresponding author press). Members of the Laminariales exhibit an alternation of heteromorphic generations of different ploidy levels. The Abstract macroscopic sporophytes are well characterized and the morphological classification within the Laminariales is A recent molecular investigation of kelp systematics based on features of this diploid generation (Setchell and revealed mitochondrial sequences that gave phylogenies Gardner 1925). Kelp gametophytes are haploid, dioe- inconsistent with those based on nuclear and chloroplast cious and sexually dimorphic; male filaments are typically sequences for the species Lessoniopsis littoralis. smaller in diameter and more branched than their female Sequence from the mitochondrial nad6 region placed L. counterparts (McKay 1933, Hollenberg 1939). Our under- littoralis in the middle of a clade of Alaria species in our standing of the microscopic, filamentous, gametophytes trees, whereas Rubisco and nuclear ribosomal DNA is poor compared with that of the sporophytes, and a sequences resolved L. littoralis within the Alariaceae, but comprehensive morphological survey of kelp gameto- distinct from Alaria.
    [Show full text]
  • Nova Scotia), Greenland, Iceland And
    An investigation into the taxonomy, distribution, seasonality and phenology of Laminariaceae (Phaeophyceae) in Atlantic Canada by Caroline Longtin BSc University of Victoria, 2006 MSc St. Francis Xavier University, 2008 A Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in the Graduate Academic Unit of Biology Supervisor: Gary W. Saunders, PhD, Biology Examining Board: Antony Diamond, PhD, Faculty of Forestry and Environmental Management (Chair) Donald Baird, PhD, Department of Biology Stephen Heard, PhD, Department of Biology External Examiner: Arthur Mathieson, PhD, Department of Biology, University of New Hampshire This dissertation is accepted by the Dean of Graduate Studies THE UNIVERSITY OF NEW BRUNSWICK August, 2014 ©Caroline Longtin, 2014 ABSTRACT The Laminariaceae is one of eight families in the order Laminariales (the kelps) and most members occur in the northern hemisphere. A recent molecular study in Atlantic Canada confirmed the presence of Laminaria digitata, Saccharina latissima and a third genetic species, which was later attributed to S. groenlandica. This third genetic species was likely overlooked in this region due to its morphological similarity to L. digitata and S. latissima. The main objective of this thesis was to investigate the taxonomy, distribution and seasonality of the Laminariaceae in Atlantic Canada and verify the taxonomic identity of the North American genetic species attributed to S. groenlandica. First, I clarified the taxonomic confusion surrounding the North American genetic species attributed to S. groenlandica. I determined that the North American genetic species currently attributed to S. groenlandica is correctly attributed to L. nigripes; therefore, Saccharina nigripes (J. Agardh) C.
    [Show full text]
  • The Ecology and Anchorage Mechanics of Kelp Holdfasts
    THE ECOLOGY AND ANCHORAGE MECHANICS OF KELP HOLDFASTS by SOPHIE MARIE DOMINIQUE SANDRINE VALERIE BOIZARD B.Sc, The University of Victoria, 1996 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE STUDIES (Botany) THE UNIVERSITY OF BRITISH COLUMBIA June 2007 © Sophie Marie Dominique Sandrine Valerie Boizard, 2007 Abstract The intertidal zone on wave-swept shores is among the most stressful environments on earth. The ability of organisms to survive and thrive in such environments depends on their ability to withstand breakage and wave dislodgement. The research presented in this thesis investigated two aspects of the biology of kelp holdfasts. I first examined whether the recruitment of the kelp Hedophyllum sessile was facilitated by the presence of holdfasts of adult conspecifics and how canopy cover and wave-exposure mediated this interaction. Field experiments indicated that adult holdfasts and substrata of high structural complexity, such as articulated coralline algae, enhanced recruitment. However, the ability of structurally complex substrata to facilitate recruitment depends largely on the extent of canopy cover and to a lesser extent on wave-exposure. Mechanisms by which canopy cover mediates substratum-specific recruitment processes may hold significant implications for population persistence and successful recruitment, especially following periods of high disturbance. Secondly, I investigated the functional morphology of the holdfast of the kelp Laminaria setchellii in relation to its role in providing attachment to the substratum and resistance against wave dislodgment. Results of field investigations indicated that the thallus of L. setchellii responds to increased wave exposure by decreasing blade size and increasing holdfast size; a concomitant increase in holdfast attachment force was not observed.
    [Show full text]
  • Laminariales, Phaeophyceae) Supports Substantial Taxonomic Re-Organization1
    J. Phycol. 42, 493–512 (2006) r 2006 Phycological Society of America DOI: 10.1111/j.1529-8817.2006.00204.x A MULTI-GENE MOLECULAR INVESTIGATION OF THE KELP (LAMINARIALES, PHAEOPHYCEAE) SUPPORTS SUBSTANTIAL TAXONOMIC RE-ORGANIZATION1 Christopher E. Lane,2 Charlene Mayes Centre for Environmental and Molecular Algal Research, University of New Brunswick, Fredericton, NB, Canada E3B 6E1 Louis D. Druehl Bamfield Marine Sciences Centre, Bamfield, BC, Canada V0R 1B0 and Gary W. Saunders Centre for Environmental and Molecular Algal Research, University of New Brunswick, Fredericton, NB, Canada E3B 6E1 Every year numerous ecological, biochemical, Key index words: Costariaceae; Laminariales; long and physiological studies are performed using branch attraction; nested analyses; phylogenetics; members of the order Laminariales. Despite the Saccharina fact that kelp are some of the most intensely stud- ied macroalgae in the world, there is significant de- bate over the classification within and among the The order Laminariales Migula, commonly called three ‘‘derived’’ families, the Alariaceae, Lamina- kelp, includes the largest algae in the world, reaching riaceae, and Lessoniaceae (ALL). Molecular phylo- up to 50 m in length (Van den Hoek et al. 1995). Kelp genies published for the ALL families have are ubiquitous in coastal waters of cold-temperate re- generated hypotheses strongly at odds with the cur- gions from the Arctic to the Antarctic, and their size rent morphological taxonomy; however, conflicting and biomass establishes a unique and essential habitat phylogenetic hypotheses and consistently low levels for hundreds of species (Steneck et al. 2002). They are of support realized in all of these studies have re- used as a food source in Asia and Europe, and are also sulted in conservative approaches to taxonomic re- economically important for their extracts (Chapman visions.
    [Show full text]
  • Cell Wall Chemistry and Tissue Structure Underlie Shifts in Material Properties of a Perennial Kelp Samuel Starko A,B, Shawn D
    EUROPEAN JOURNAL OF PHYCOLOGY, 2018 https://doi.org/10.1080/09670262.2018.1449013 Cell wall chemistry and tissue structure underlie shifts in material properties of a perennial kelp Samuel Starko a,b, Shawn D. Mansfielda,c and Patrick T. Martonea,b aDepartment of Botany and Beaty Biodiversity Research Centre, The University of British Columbia, 6270 University Blvd., Vancouver, BC, V6T1Z4, Canada; bBamfield Marine Sciences Centre, 100 Pachena Rd., Bamfield, BC, V0R1B0, Canada; cDepartment of Wood Sciences, The University of British Columbia, 2424 Main Mall, Vancouver, V6T1Z4, Canada ABSTRACT Laminaria is an abundant kelp genus in temperate nearshore ecosystems that grows with a circannual ‘stop-start’ pattern. Species of Laminaria play important ecological roles in kelp forests worldwide and are harvested commercially as a source of food and valuable extracts. In order to evaluate seasonal differences in tissue properties and composition, we compared the material properties, histology and cell-wall composition of overwintering blades with newly synthesized, actively growing blades from Laminaria setchellii. We found that overwintering blades were fortified with a thicker cortex and increased cell wall investment, leading to increased material strength. Overwintering tissues were composed of higher proportions of cellulose and fucose-containing polysaccharides (i.e. FCSPs, fucoidans) than newly formed blades and were found to possess thicker cell walls, likely to withstand the waves of winter storms. Chemical cell wall profiling revealed that significant proportions of fucose were associated with cellulose, especially in overwintering tissues, confirming the associa- tion between cellulose and some fucose-containing polysaccharides. Changes in material properties during the resting phase may allow these kelps to retain their non-growing blades through several months of winter storms.
    [Show full text]
  • Dynamics of Carbon Allocation in a Deep-Water Population of the Deciduous Kelp Pleurophycus Gardneri (Laminariales)
    MARINE ECOLOGY PROGRESS SERIES Vol. 309: 143–157, 2006 Published March 15 Mar Ecol Prog Ser Dynamics of carbon allocation in a deep-water population of the deciduous kelp Pleurophycus gardneri (Laminariales) Clare Margaret Dominik1,*, Richard C. Zimmerman1, 2 1The California State University, Moss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, California 95039, USA 2Present address: Department of Ocean, Earth and Atmospheric Sciences, 4600 Elkhorn Avenue, Old Dominion University, Norfolk, Virginia 23529, USA ABSTRACT: Pleurophycus gardneri (Laminariales) is common in the low intertidal of the Northeast Pacific, but dominates many deep (30 to 40 m) rocky reefs in central California. Seasonal dynamics of productivity and resource allocation of a deep-water population of this deciduous, stipitate kelp were studied to understand how blade abscission affects the annual carbon budget. Patterns of growth, metabolism, and carbon storage and mobilization were measured monthly for 1 yr relative to in situ light and temperature, and used to model the annual carbon budget. The resulting carbon budget was used to determine if blade abscission effectively reduced respiratory demand during the winter period of low light availability. Metabolic properties (photosynthesis, photoacclimation, and respira- tion) were seasonally constant and showed evidence of photoacclimation to this deep, low-light environment. Blades grew between February and July, followed by senescence and sloughing from August to December. Concentrations of laminaran and mannitol increased in the blades from the onset of sloughing in August until just prior to blade abscission in mid-December, suggesting translocation of these carbohydrates may have occurred from the blade to the stipe and holdfast.
    [Show full text]
  • Population Biology of Undaria Pinnatifida in Central California
    POPULATION BIOLOGY OF UNDARIA PINNATIFIDA IN CENTRAL CALIFORNIA A Thesis Presented to The Faculty of the Department of Marine Science San Jose State University In Partial Fulfillment of the Requirements for the Degree Master of Science by Diana Kohtio May 2008 ©2008 Diana Kohtio ALL RIGHTS RESERVED ABSTRACT POPULATION BIOLOGY OF UNDARIA PINNATIFIDA IN CENTRAL CALIFORNIA by Diana Kohtio This study combined monitoring and experimental techniques to examine natural population parameters and physiological response to temperature of the invasive kelp Undaria pinnatifida in Monterey Harbor, California. Natural population density, reproductive condition, and seawater temperature were recorded throughout a 20-month study. Recruitment was sampled in experimental sporophyte density plots throughout a 9-month experiment. Physiology experiments were conducted in two temperature treatments over a 55-day period coincident with reproduction measurements and nutrient analysis. Natural population fluctuation and reproductive condition appeared to respond to seasonal variations in temperature range. Warm temperature treatments increased C:N and blade senescence but decreased time to reproduction and peak spore output. Sporophyte density reduced recruitment at high levels, likely resulting from intra-specific competition. Because Undaria pinnatifida is an opportunistic species responding to changes in an unpredictable environment it may have a distinct advantage when it comes to invasion success. ACKNOWLEDGEMENTS I would like to thank my parents for giving me the opportunity to attend graduate school and conduct this research. Thanks to the Beerpigs for all of their kind support and insightful feedback throughout my tenure at Moss Landing Marine Laboratories. Special thanks to my advisor Mike Graham and committee members Steve Lonhart and Kenneth Coale for their guidance.
    [Show full text]
  • Enrichment on Nearshore Habitats, with a Focus on Eelgrass and Kelp
    Po Potential impacts of nutrient over- enrichment on nearshore habitats, with a focus on eelgrass and kelp Bart Christiaen, Helen Berry, Pete Dowty, Jeff Gaeckle, Lisa Ferrier The nearshore environment Jonannessen & MacLennan 2007 • High tide line to end of photic zone • Most of Puget Sound: narrow band • Diverse community of plants and algae Seagrass species in Washington State Native (Zostera marina) Non-native, dwarf or Japanese Diversity (Zostera japonica) Eelgrass (Zostera) Surfgrass (Phyllospadix) Important but vulnerable ©Aaron Baldwin Importance • Habitat for a wide range of organisms • Fuels the detrital foodweb • Sensitive to nutrient over enrichment ©DNR ©Ron Thom Physiological response to high - water column NO3 Zostera marina evolved in N poor conditions: no product inhibition feedback for nitrate uptake and assimilation - NO3 assimilation to amino acids is metabolically “expensive”. Stressors - High water NO3 concentrations over extended periods of time: eelgrass becomes internally C- limited Lower productivity and survival ©Aaron Barna Competitive interactions under increased N load Stressors • Higher incidence of phytoplankton blooms, epiphytes or overgrowth by green algae • Lower light availability • Lower shoot density, reduces max depth of seagrass beds ©DNR Increased sulfide intrusion in rhizosphere Microbial respiration of organic matter in anoxic sediments: sulfate reduction Sulfide is common in marine sediments O and Zostera marina is adapted to 2 moderate sulfide concentrations Increased sulfide intrusion under
    [Show full text]
  • Supplementary Material
    Supplementary material References retrieved from database searches Lundy, a statutory marine nature reserve Nature Conservancy Council, Peterborough. The Mercantile marine magazine and record of the Royal Naval Reserve William Foster : Imray & Son, Minories, & Tower Hill, E., London. The mercantile marine magazine and record of the Royal Naval Reserve Imray & Sons, Minories, & Tower Hill, E., London. PROCEEDINGS OF AN INTERNATIONAL CONFERENCE ON MARINE PARKS AND RESERVES- MARINE PARKS CENTER JAPAN ENVIRONMENTAL AGENCY OF JAPAN- NATIONAL PARKS ASSOCIATION OF JAPAN- IUCN- INTERNATIONAL UNION FOR CONSERVATION NATURE AND NATURAL RESOURCES. (1973) Solid waste disposal offshore. Petroleum Engineer International, 45, 86-88. (1976) SCIENCE AND TECHNOLOGY OF OIL SHALE. Sci and Technol of Oil Shale. (1976) Skomer Island marine reserve. Marine Pollution Bulletin, 7, 204-204. (1977) Promotion of the establishment of Marine Parks and reserves in the Northern Indian Ocean including the Red Sea and Persian Gulf (Tehran, Iran, March 1975) : 169 pages, $8.50, 1976, International Union for Conservation of Nature and Natural Resources, Morges, Switzerland. Marine Policy, 1, 86-86. (1980) Nature conservancy council. Fifth report covering the period 1 April 1978 - 31 March 1979. Nature conservancy council. Fifth report covering the period 1 April 1978 - 31 March 1979. (1981) Cape Rodney to Okakari point marine reserve. Department of Lands and Survey N.Z., [Wellington]. (1981) Controversy over UK marine reserves. Marine Pollution Bulletin, 12, 106- 106. (1983) The U.S. stevedoring and marine terminal industry. (1984) Naval Reserve - 16x5 - Formula for Merchant -Marine Preparedness. Marine Engineering Log, 89, 66-67. (1987) New Zealand's course for marine reserves : Ballantine, Bill, 1987.
    [Show full text]
  • A Molecular Assessment of Northeast Pacific Alaria Species
    Molecular Phylogenetics and Evolution 44 (2007) 634–648 www.elsevier.com/locate/ympev A molecular assessment of northeast Pacific Alaria species (Laminariales, Phaeophyceae) with reference to the utility of DNA barcoding Christopher E. Lane a,*, Sandra C. Lindstrom b, Gary W. Saunders a a Centre for Environmental and Molecular Algal Research, Department of Biology, University of New Brunswick, Fredericton, NB, Canada E3B 6E1 b Department of Botany, #3529-6270 University Building, University of British Columbia, Vancouver, BC, Canada V6T 1Z4 Received 21 August 2006; revised 2 February 2007; accepted 16 March 2007 Available online 4 April 2007 Abstract Despite their relatively complex morphologies, species in the genus Alaria Greville are notoriously difficult to identify with certainty. Morphological characters, often influenced by environmental factors, make individuals in similar habitats artificially appear related. Spe- cies identification would, therefore, benefit greatly from the application of molecular tools. We applied DNA barcoding, using the 50 end of the cytochrome c oxidase I (coxI-50) gene from the mitochondrial genome, to define species limits and relationships in northeast Pacific populations of Alaria. This emerging technique is being employed to catalogue species diversity worldwide, particularly among animals, and it has been shown to be sensitive enough to discriminate between closely related species. However, the utility of this marker for iden- tifying or categorizing the majority of life remains unclear. We compared the resolution obtained with this marker to two other molecular systems commonly used in algal research: the nuclear internal transcribed spacer (ITS) of the ribosomal cistron, and the plastid Rubisco operon spacer (rbcSp). In agreement with previous results, Alaria fistulosa Postels & Ruprecht, with its distinct morphological, ecological and molecular features, stands apart from the other species in the genus and we establish Druehlia gen.
    [Show full text]