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Title: What are algal turfs?: Towards a better description of turfs
Description: The use of standardised classifications, or operational definitions, is essential if different researchers are to measure and compare similar entities. In the marine realm, algal 'turfs' are increasingly reported to be globally expanding at the expense of kelps and canopy-forming algae. However, ecological research about the underlying drivers of this shift is limited by a vague and inconsistent definition of what exactly a turf is. In order to stimulate more effective descriptions of 'turfs' and facilitate communication of research outcomes and comparisons across studies, we reviewed the use of the term turf in ecological studies of temperate coasts and coral reefs and (1) identified the main types and distribution of algal assemblages known as 'turfs', (2) examined the descriptions of turfs so that we may recognise some general characteristics, including those contingent on environmental conditions; and (3) offered character descriptions that could improve communication and comparisons. These descriptors centre on reporting information on the morphology, height, density of thalli, the amount of sediment trapped in turfs and a description of the area covered by turfs, including their patchiness and persistence. Our review recognised these as common attributes that could be usefully described across a wide range of circumstances and provide insights into the ecology of turfs and their interactions with other assemblages in a community. The use of common descriptors would provide the term 'turf' with greater scientific value. © Inter-Research 2014., Seaweeds
Author: Connell, Foster, Airoldi
Date: 2014-01-01T00:00:00Z

Title: The effects of storm-drains with periodic flows on intertidal algal assemblages in 'Ewa Beach (O'ahu), Hawai'i,
Description: Storm-water drainage systems have potential to collect and focus nutrient enriched runoff into coastal systems. Storm-drain effluent could support macroalgal production and result in altered communities. To test this hypothesis, we assessed species composition and percent cover of native and non-native benthic macroalgae at eight intertidal sites along 'Ewa Beach, Hawai'i. Three sites contain storm-drainage outlets (drain 16-52. acres) that deliver effluent into the intertidal zone whereas five sites were located ≥ 100. m away and served as comparisons to determine differences related to the presence of storm-water. Results revealed lush and diverse macroalgal assemblages, similar at all sites. Furthermore, the abundance of non-native species (Acanthophora spicifera, Hypnea musciformis) was not related to presence of storm-drains. The finding that macroalgal assemblages are not related to storm-waters is contrary to an earlier investigation in the same location and underscores the importance of sampling design and habitat variation when assessing impacts. © 2013 Elsevier Ltd., Seaweeds, CODEN: MPNBA, ,
Author: Cox, Foster
Date: 2013-01-01T00:00:00Z

Title: Abiotic regulation of investment in sexual versus vegetative reproduction in the clonal kelp Laminaria sinclairii (Laminariales, Phaeophyceae),
Description: Clonal kelp taxa may reproduce both sexually and vegetatively resulting in a potential trade-off in the allocation of acquired carbon and nitrogen resources. Such trade-offs may dictate a different response of clonal kelps to varying environmental conditions relative to aclonal kelp taxa. Laboratory temperature and nutrient manipulation experiments demonstrated that investment in sexual and vegetative reproduction in Laminaria sinclairii (Harv. ex Hook. f. et Harv.) Farl., C. L. Anderson et D. C. Eaton was regulated by different abiotic factors. Sorus production (investment in sexual reproduction) and blade growth were significantly higher at 12°C compared to 17°C, regardless of nutrient concentration. Net carbon storage and depletion in rhizomes were observed in the low- and high-temperature treatments, respectively, suggesting that carbon stores were not responsible for increased growth. Rhizome elongation (investment in vegetative reproduction), on the other hand, was significantly higher in 12μM NO3- than in 2μM NO3-, irrespective of temperature. This increase in rhizome growth was concurrent with elevated rhizome percent tissue nitrogen levels also observed in treatments with higher nutrients, again indicating a growth response to treatment independent of previous nutrient stores. These results suggest that regulation of growth and investment in sexual reproduction in L. sinclairii is similar to that in aclonal kelps (i.e., warmer temperatures result in decreased reproductive output). Additionally, depletion of carbon and nitrogen from rhizomes in suboptimal conditions confirms the role of clonal kelp rhizomes in carbon and nutrient storage. © 2011 Phycological Society of America., Seaweeds, CODEN: JPYLA, ,
Author: Demes, Graham
Date: 2011-01-01T00:00:00Z

Title: Can stormwater be detected by algae in an urban reef in Hawai'i?,
Description: Nitrogen (N) enrichment of tropical reefs can result in the dominance of invasive algae. The invasive alga Acanthophora spicifera and the native alga Laurencia nidifica are part of a diverse reef assemblage in 'Ewa Beach, O'ahu. Their N contents and δ15N values were investigated to determine if N was enriched and to evaluate potential nitrogenous sources near and removed from storm-drain outlets. δ15N values of algae (3.8-17.7‰) were within and above the range for algae around the island (1.9-11.9‰). Elevated algae N isotope values (δ15N>+7‰, [N]>1.6%) and seawater nitrate+nitrite levels (0.59-7.93μM) indicated a mixed, high nutrient environment. The overlap in δ15N values with multiple nitrogenous sources precluded identification. However, spatial and temporal patterns did not support stormwater as the dominant, nitrogenous source. Patterns were congruent with algal incorporation of terrestrial derived N, subjected to a high degree of biogeochemical cycling. © 2013 Elsevier Ltd., Seaweeds, CODEN: MPNBA, ,
Author: Cox, Smith, Popp, Foster, Abbott
Date: 2013-01-01T00:00:00Z

Title: Condensation of the isoprenoid and amino precursors in the biosynthesis of domoic acid
Description: Understanding how environmental signals regulate production of domoic acid in blooms of Pseudo-nitzschia spp. at a molecular level requires description of the biochemical pathway to this kainoid neurotoxin. Precursor feeding studies have suggested domoic acid arises from the condensation of the C 10 isoprenoid geranyl diphosphate with glutamate, but the specific reactions leading to domoic acid from these precursors remain undescribed. Here, we develop a method to derivatize domoic acid with propyl chloroformate that enables gas chromatography-mass spectrometry (GC-MS) analysis to measure incorporation of stable isotopes into domoic acid generated in cultures incubated with isotopically-labeled substrates. We apply this method to demonstrate that both 2H from [1- 2H 2]geraniol are incorporated into domoic acid, suggesting that the condensation of geranyl diphosphate with an amino group occurs by nucleophilic substitution of the diphosphate rather than by oxidation of geraniol to the aldehyde before reaction with an amino group to form an imine. Ultimately, these and similar studies will facilitate the identification of DA biosynthetic enzymes and genes which will enable the study of how environmental factors regulate DA biosynthesis at the molecular level. © 2011 Elsevier Ltd., Seaweeds, CODEN: TOXIA
Author: Savage, Smith, Clark, Saucedo
Date: 2012-01-01T00:00:00Z

Title: Living rhodolith beds in the Gulf of California and their implications for paleoenvironmental interpretation,
Description: Subtidal surveys in the southwestern Gulf of California indicate that rhodolith beds are widely distributed, major sources of carbonate sediments, and habitats of high biodiversity. Beds with abundant branched rhodoliths ranging in size from 2 to 10 cm (longest dimension) have been found in two main types of environments: (1) gently sloping, subtidal soft bottoms with moderate wave action (wave beds; 2 to 12 m deep), and (2) relatively level bottoms in channels with tidal currents (current beds; below 12 m). Large individuals (to 11 cm) with up to 1 cm thick, densely packed branches are also found dispersed among sand and cobbles on more wave exposed shores. The relative abundance of fruticose forms and the sphericity and branch density of individual thalli are generally higher in wave beds than in current beds. Morphology within wave beds varies along gradients of water motion, with higher branch densities, more apical branching, and more branch fusions present as water motion increases. The extent to which these morphological differences represent different taxa is being evaluated. The abundance of rhodoliths in Pliocene and Pleistocene carbonate deposits and modern sediments indicates that this community has long been an important feature of nearshore environments in the Gulf. Our results suggest that measurements of a combination of morphological characters in populations of fossil rhodoliths, combined with detailed, small-scale stratigraphic analyses, may provide good estimates of paleoenvironmental conditions., Cited By (since 1996):6, Seaweeds, ,
Author: Foster, Riosmena-Rodriguez, Steller, Woelkerling
Date: 1997-01-01T00:00:00Z

Title: Application of color infrared aerial photography to assess macroalgal distribution in an eutrophic estuary, upper Newport Bay, California,
Description: Newport Bay is a large estuary in southern California that is subject to anthropogenic nutrient loading, eutrophication, and hypoxia. Ground-based methods of assessing algal extent for monitoring and management are limited in that they cannot provide a synoptic view of algal distribution over comparatively large areas. The goal of this study was to explore the application of color infrared aerial photography as an alternative for analyzing the changes in the abundance of exposed macroalgae. Three surveys combining remote sensing (color infrared aerial photography) and ground-based sampling to quantify macroalgal mat coverage were carried out in Upper Newport Bay (UNB) between July and October 2005. Airborne photographs (scale 1:6000) collected during daytime low tides, clear skies, and appropriate sun angle were digitized to 25-cm resolution, orthorectified, georegistered, and combined into three mosaic composite digital images: one for each survey. During each aerial photography survey, macroalgal percent cover was measured on the ground by the point-intercept method in a 6.25-m2 area at ca. 30 locations distributed along the water's edge throughout the intertidal mudflat area. There were three main types of cover: Ulva spp. (green algae), Ceramium spp. (red algae), and bare surface (mud and mussel beds). To analyze similarities between spectral signatures in the images and cover types, the pixels corresponding to the ground samples from each survey were grouped into clusters based on similarity of their spectral signatures. To establish relationships between spectral signatures in the images and cover as determined from ground data, pixels in each composite image corresponding to ground samples from the same day that were characterized by > 90% of one cover type were attributed to that cover type. Ground samples comprised of a mixture of cover types were used for accuracy assessment. Before classification, each digital image was transformed by the Minimum Noise Fraction Rotation method to remove noise and enhance contrast between the classes. For classification of each composite image, the Spectral Angle Mapper scheme was used: all pixels in each image were attributed to the identified classes and the areal extent of each class was estimated. According to these assessments, the macroalgal coverage in UNB increased from 37% in July to 57% in September to 80% in October, and during this time Ulva spp. replaced Ceramium spp. as the dominant alga. This analysis showed that color infrared aerial photography is an effective tool for assessing estuarine, intertidal macroalgal coverage. © 2007 Estuarine Research Federation., Cited By (since 1996):6, Seaweeds, ,
Author: Nezlin, Kamer, Stein
Date: 2007-01-01T00:00:00Z

Title: Variability in per capita oogonia and sporophyte production from giant kelp gametophytes (Macrocystis pyrifera, Phaeophyceae)
Description: Vegetative growth and fertility of kelp gametophytes are thought to be antagonistic, such that most successful kelp recruitment is assumed to result from fertilization of single oogonia released from unicellular female gametophytes. We used laboratory culture experiments to study the effect of temperature and nutrient addition on the per capita production of oogonia and sporophytes from Macrocystis pyrifera female gametophytes. Our results indicate that individual multicellular female gametophytes can give rise to more than one oogonium and that per capita oogonia production significantly increases with the enhancement of culture conditions (i.e., decreased temperature and increased nutrient concentration). Furthermore, the production of multiple oogonia per female often led to the production of multiple sporophytes per female. We discuss the importance of these results relative to variability in M. pyrifera life histories (e.g., annual vs. perennial) and their likely ecological and evolutionary consequences., Cited By (since 1996):11, Seaweeds
Author: Muñoz, Hernández-González, Buschmann, Graham, Vásquez
Date: 2004-01-01T00:00:00Z

Title: The kelp highway hypothesis: Marine ecology, the coastal migration theory, and the peopling of the Americas
Description: In this article, a collaborative effort between archaeologists and marine ecologists, we discuss the role kelp forest ecosystems may have played in facilitating the movement of maritime peoples from Asia to the Americas near the end of the Pleistocene. Growing in cool nearshore waters along rocky coastlines, kelp forests offer some of the most productive habitats on earth, with high primary productivity, magnified secondary productivity, and three-dimensional habitat supporting a diverse array of marine organisms. Today, extensive kelp forests are found around the North Pacific from Japan to Baja California. After a break in the tropicswhere nearshore mangrove forests and coral reefs are highly productivekelp forests are also found along the Andean Coast of South America. These Pacific Rim kelp forests support or shelter a wealth of shellfish, fish, marine mammals, seabirds, and seaweeds, resources heavily used historically by coastal peoples. By about 16,000 years ago, the North Pacific Coast offered a linear migration route, essentially unobstructed and entirely at sea level, from northeast Asia into the Americas. Recent reconstructions suggest that rising sea levels early in the postglacial created a highly convoluted and island-rich coast along Beringia's southern shore, conditions highly favorable to maritime hunter-gatherers. Along with the terrestrial resources available in adjacent landscapes, kelp forests and other nearshore habitats sheltered similar suites of food resources that required minimal adaptive adjustments for migrating coastal peoples. With reduced wave energy, holdfasts for boats, and productive fishing, these linear kelp forest ecosystems may have provided a kind of kelp highway for early maritime peoples colonizing the New World., Cited By (since 1996):22, Seaweeds
Author: Erlandson, Graham, Bourque, Corbett, Estes, Steneck

Title: Damage and recovery in intertidal Fucus gardneri assemblages following the Exxon Valdez oil spill,
Description: Cited By (since 1996):19 Seaweeds, CODEN: MESED, In March 1989, the 'Exxon Valdez' spilled over 10 million gallons (ca 38 million I) of crude oil into Prince William Sound, Alaska , USA. The spill was followed by massive clean-up using hot seawater at high pressure as well as other mechanical and chemical techniques. We studied initial damage and subsequent recovery in the upper margin of the Fucus gardneri assemblage on protected shores by comparing sites that were unoiled, oiled and cleaned with hot water at high pressure, and oiled but less intensely cleaned. F. gardneri cover averaged 80% on unoiled sites but< 1 % on all oiled and cleaned sites 18 mo after the spill. The abundances of barnacles, littorine snails and limpets varied among sites and species, and this variation was associated in part with differences in their life histories. F. gardneri cover was still extremely low on oiled and cleaned sites 2.5 yr after the spill. Holdfasts that persisted after cleaning did not resprout. F. gardneri recruitment was lowest at intensely cleaned sites, and most recruits occurred in cracks near adults. Recruits were less abundant under adult canopies but placing canopies over recruits did not decrease their survivorship over 5 mo. Natural weathering of tar was rapid, with most marked patches gone in less than 1 yr. We conclude that intense mechanical cleaning following this oil spill increased damage and slowed recovery. Such methods should be avoided if reduction of environmental damage is the primary objective of post-spill management decisions. The recovery of F. gardneri at its upper margin might be enhanced by devices that retain moisture and increase substratum rugosity., ,
Author: Devogelaere, Foster
Date: 1994-01-01T00:00:00Z

Title: Evolution of Macrocystis spp. (Phaeophyceae) as determined by ITS1 and ITS2 sequences
Description: Macrocystis (Lessoniaceae) displays an antitropical distribution, occurring in temperate subtidal regions along western North America in the northern hemisphere and throughout the southern hemisphere. We used the noncoding rDNA internal transcribed spacer regions (ITS1 and ITS2) to examine relatedness among (1) Macrocystis and several genera of Laminariales, (2) four species of Macrocystis (M. integrifolia Bory from the northern hemisphere, M. angustifolia Bory and M. laevis Hay from the southern hemisphere, and M. pyrifera [L.] C. Ag. from both hemispheres), and (3) multiple clones of several individuals. Of the taxa included in our phylogenetic analysis, the elk kelp, Pelagophycus porra (Lem.) Setch., was the sister taxon to Macrocystis spp. Macrocystis individuals from the southern hemisphere (representing three species) formed a strongly to moderately supported clade, respectively, when the ITS1 and ITS2 sequences were analyzed separately. No distinction was detected between the two species in the northern hemisphere. Thus, Macrocystis may be a monospecific genus (M. pyrifera). A northern-hemisphere-to-southern-hemisphere pattern of dispersal was inferred, because northern-hemisphere individuals were more diverse and displayed paraphyletic clades, whereas southern-hemisphere individuals were less diverse and formed a monophyletic clade. High intraindividual variation in ITS1 sequences was observed in one individual from Santa Catalina Island (CA), suggesting very recent and rapid mixing of genotypes from areas to the north and Baja California (Mexico) or introgressive hybridization with Pelagophycus., Cited By (since 1996):67, Seaweeds, CODEN: JPYLA
Author: Coyer, Smith, Andersen
Date: 2001-01-01T00:00:00Z

Title: The effects of insolation and grazing on populations of the splash zone alga Prasiola meridionalis (Chlorophyta),
Description: Field experiments at two sites assessed the effects of insolation and gastropod grazing on the distribution and abundance of Prasiola meridionalis Setchell et Gardner, a green alga that occurs in the upper splash zone (supralittoral) on guano-covered rocks. At site 1, a sun-exposed horizontal rock where the alga occurs seasonally and grazers were rare, blades appeared in the early spring and died back in early summer. Lack of gastropod grazers and persistence of blades in experimentally shaded plots showed that increased insolation or some associated factor (or factors) was responsible for temporal variation at this site. At site 2, the alga grew in a distinct, perennial band on a shaded vertical rock face with abundant gastropod grazers. These grazers were excluded from long vertical plots that extended from the lower portion of the P. meridionalis band down to a zone of the red alga Endocladia muricata (Postels et Ruprecht) J. Agardh more than 2 m below. The results showed that grazing set the proximate lower limit of P. meridionalis at site 2, and variation in the abundance of the alga within its zone at this site was associated with seasonal climate changes and feeding by mites. Thus, while insolation and grazing can both affect populations of P. meridionalis, their relative importance varied between sites., Cited By (since 1996):4, Seaweeds, CODEN: PYCOA, ,
Author: Anderson, Foster
Date: 1999-01-01T00:00:00Z

Title: Effects of shade from multiple kelp canopies on an understory algal assemblage,
Description: We examined the effects of shade from multiple kelp canopy layers (surface Macrocystis pyrifera canopy, understory Pterygophora californica canopy), both individually and in combination, on an understory algal assemblage in a central Californian kelp forest. The removal of both kelp canopies resulted in a dense recruitment of the understory brown alga Desmarestia ligulata that formed a third canopy layer, which significantly decreased bottom light and the abundance of understory red algae. We subsequently created an additional canopy treatment by removing this third canopy layer. In general, the understory red algae fluctuated seasonally with winter swell intensity, changes in kelp canopy cover, and grazing; and although species richness increased significantly with increased bottom light, red algal bottom cover did not respond significantly to the canopy clearings until 2 yr after the canopies were initially cleared. Red algal cover within the Pterygophora canopy treatment was similar to that in the control treatment. In the absence of Pterygophora, the Macrocystis canopy treatment and 'no canopy' treatment were found to have greater red algal cover and species richness. Individual understory species were rare, which resulted in small effects sizes and thus low statistical power. However, when grouped post hoc, according to how they responded to the canopy clearings (i.e. response groups), we were able to detect canopy treatment effects as much as 1 yr earlier. This method identified that some understory red algae adapted to areas of canopy removal (light-adapted), and others adapted to a variety of light regimes (shade-tolerant). We were able to classify the light-adapted algae into 2 subgroups: the high-light species and the intermediate-light species. Although this method of grouping was done post hoc, our results indicate that it may provide the clearest assessment of how understory algae respond to shading from kelp canopies., Cited By (since 1996):40, Seaweeds, CODEN: MESED, ,
Author: Clark, Edwards, Foster
Date: 2004-01-01T00:00:00Z

Title: Complementarity in marine biodiversity manipulations: Reconciling divergent evidence from field and mesocosm experiments,
Description: Mounting concern over the loss of marine biodiversity has increased the urgency of understanding its consequences. This urgency spurred the publication of many short-term studies, which often report weak effects of diversity (species richness) driven by the presence of key species (the sampling effect). Longer-term field experiments are slowly accumulating, and they more often report strong diversity effects driven by species complementarity, calling into question the generality of earlier findings. However, differences among study systems in which short- and long-term studies are conducted currently limit our ability to assess whether these differences are simply due to biological or environmental differences among systems. In this paper, we compared the effect of intertidal seaweed species richness on biomass accumulation in mesocosms and field experiments using the same pool of species. We found that seaweed species richness increased biomass accumulation in field experiments in both short (2-month) and long (3-year) experiments, although effects were stronger in the longterm experiment. In contrast, richness had no effect in mesocosm experiments, where biomass accumulation was completely a function of species identity. We argue that the short-term experiments, like many published experiments on the topic, detect only a subset of possible mechanisms that operate in the field over the longer term because they lack sufficient environmental heterogeneity to allow expression of niche differences, and they are of insufficient length to capture population-level responses, such as recruitment. Many published experiments, therefore, likely underestimate the strength of diversity on ecosystem processes in natural ecosystems. © 2008 by The National Academy of Sciences of the USA., Cited By (since 1996):33 Seaweeds, CODEN: PNASA, ,
Author: Stachowicz, Best, Bracken, Graham
Date: 2008-01-01T00:00:00Z

Title: Characterization of a cDNA encoding glutamine synthetase from the marine diatom Skeletonema costatum (Bacillariophyceae),
Description: A cDNA-encoding glutamime synthetase (GS) was isolated from the marine diatom Skeletonema costatum (Greville) Cleve by PCR amplification. Nucleic acid and deduced amino acid sequences of the diatom GS were greater than 50% identical to GS from green algae and vascular plants, and phylogenetic analysis established the diatom GS as a member of the GSII gene family. The presence of an N-terminus signal sequence, identified on the basis of sequence similarity with other chloroplast-localized proteins from diatoms, suggests that the encoded GS isoenzyme is localized to the chloroplast. The GS mRNA was present in log-phase cells grown with either nitrate or ammonium as the sole added nitrogen source. Results from Southern blot analysis of genomic DNA suggested that the cDNA isolated in this study was either a member of a small, highly conserved gene family or that there was allelic variation within the region examined. Phylogenetic analyses further indicated that genes encoding GS from the diatom and two species of green algae diverged prior to the gene duplication, to the isoenzymes in vascular plants, supporting the hypothesis that GS isoenzymes in diatoms, green algae, and vascular plants arose through independent evolutionary events., Cited By (since 1996):16, Seaweeds, CODEN: JPYLA, ,
Author: Robertson, Smith, Alberte
Date: 1999-01-01T00:00:00Z

Title: Diver disturbance in kelp forests,
Description: Recreational SCUBA diving has greatly increased in the past 20 years and has potential to cause significant disturbances to subtidal reefs. While diver disturbance on coral reefs has been assessed in a number of studies, disturbances in temperate kelp forests have not been previously examined. We estimated diver disturbance in southern Monterey Bay giant kelp, Macrocystis pyrifera, forests by following 42 divers in summer 1997 and recording their activity. During a 0.5 hour dive, the average diver contacted the bottom 43 times, touched 4 animals, and detached 2 algal blades. An estimated 65,000 diver-days are spent in these kelp forests every year, resulting in a potential loss of 130,000 algal blades and considerable benthic disturbances. The effects of these impacts and mitigation for them should be considered in proposals to establish and manage marine protected areas., Cited By (since 1996):2, Ecology, Seaweeds, ,
Author: Schaeffer, Foster, Landrau, Walder
Date: 1999-01-01T00:00:00Z

Title: Dynamics of carbon allocation in a deep-water population of the deciduous kelp Pleurophycus gardneri (Laminariales),
Description: 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 respiration) 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. Carbon budget estimates revealed that scalar irradiance measures overestimated the light available for photosynthesis of these paddle-shaped kelp blades by 50 to 75%. The calculations also revealed that blade retention allowed for the maintenance of positive carbon balance throughout the year. Thus, conservation of the internal carbon reserve for metabolic survival during the low-light period does not appear to be a viable explanation for the deciduous life history of P. gardneri. Abscission may reduce hydrodynamic drag, thus minimizing the probability of dislodgment of entire plants during winter storm events, or promote spore dispersal as abscised blades and sori drift away from the parent holdfast. © Inter-Research 2006., Cited By (since 1996):3, Seaweeds, CODEN: MESED, ,
Author: Dominik, Zimmerman
Date: 2006-01-01T00:00:00Z

Title: Settlement and post-settlement processes limit the abundance of the geniculate coralline alga Calliarthron on subtidal walls,
Description: Cover of geniculate coralline algae is significantly greater on subtidal platforms than on vertical walls in a central California kelp forest. To determine the cause(s) of this pattern, settlement and growth of Calliarthron were compared on horizontal and vertical substrata attached to platforms or walls. Recruitment on horizontal substrata attached to reef walls indicated that spores were abundant along the walls. Densities of recruits were significantly smaller on vertical substrata attached to walls than on horizontal substrata attached to platforms, indicating that Calliarthron settlement is reduced on vertical substrata. Growth of basal crusts and the densities of fronds were also significantly greater on horizontal substrata attached to platforms than on vertical substrata attached to walls. Irradiance reaching wall surfaces was less than irradiance reaching platform surfaces. We suggest that light reaching wall surface is low enough to affect Calliarthron growth. These results indicate that the low abundance of Calliarthron on subtidal walls is a result of poor recruitment and slow growth. © 2002 Elsevier Science B.V. All rights reserved., Cited By (since 1996):13, Seaweeds, CODEN: JEMBA, ,
Author: Goldberg, Foster
Date: 2002-01-01T00:00:00Z

Title: Effects of long-term kelp canopy exclusion on the abundance of the annual alga Desmarestia ligulata (Light F),
Description: Experiments in a central California Macrocystis pyrifera (L.) C.A. Agardh forest examined the effects of long-term (six year) kelp canopy exclusion on the abundance of the annual brown alga Desmarestia ligulata (Light F). Exclusion of both surface and subsurface kelp canopies from replicate clearings within stillwater Cove, CA, USA showed that D. ligulata sporophyte recruitment is opportunistic, with more sporophytes occurring in areas where canopies were excluded than under control canopies. Kelp canopy exclusion also increased spring and summer bottom irradiances, and resulted in a steady increase of perennial turf algae over the six-year study. This, in turn, led to a decrease in the availability of nongeniculate coralline algae (the primary substratum on which D. ligulata recruits). Subsequently, the annual maximum abundance of D. ligulata sporophytes decreased in the Canopy clearings, but did not change under control canopies. Removal of turf algae from experimental plots further increased bottom irradiances and significantly enhanced D. ligulata recruitment. When released from apparent competition for light and space, D. ligulata sporophytes exhibited an annual life history, with recruitment occurring during a two-week period (April 4- April 17) in the spring, and maximum bottom cover occurring in the summer (July). The onset of Desmarestia sporophyte recruitment was closely associated with seasonal increases in daylength and rapid decreases in ocean temperature. These results indicate that the Desmarestia sporophyte life history is both annual and opportunistic, with the onset of recruitment stimulated by predictable, seasonal changes in environmental conditions, and the magnitude of recruitment modified by stochastic processes that affect the availability of light and space. Comparison of these results with those from similar studies indicate that they are robust and suggest that they may be generalized over broad temporal and spatial scales., Cited By (since 1996):43, Seaweeds, CODEN: JEMBA, ,
Author: Edwards
Date: 1998-01-01T00:00:00Z

Title: Composition, distribution, and abundance of deep-water (>30 m) macroalgae in central California,
Description: The deep-water macroalgal assemblage was described at 14 sites off the central California coast during 1999 and 2000 from SCUBA and remotely operated vehicle sampling. The stipitate kelp Pleurophycus gardneri Setchell & Gardner, previously thought to be rare in the region, was abundant from 30 to 45 m, forming kelp beds below the well-known giant kelp forests. Macroalgae typically formed three broadly overlapping zones usually characterized by one or a few visually dominant taxa: 1) the upper "Pleurophycus zone" (30-45 m) of stipitate kelps and Desmarestia spp. with a high percent cover of corallines, low cover of uncalcified red algae, and rare green algae; 2) a middle "Maripelta zone" (40-55 m) with other uncalcified red algae and infrequent corallines and green algae; and 3) a zone (55-75 m) of infrequent patches of non-geniculate coralline algae. The green alga Palmophyllum umbracola Nelson & Ryan, not previously reported from the Northeast Pacific, was found over the entire geographical range sampled from 35 to 54 m. Year-round profiles of water column irradiance revealed unexpectedly clear water with an average K0 of 0.106·m-1. The low percent surface irradiance found at the average lower macroalgal depth limits in this study (0.56% for brown algae, 0.12% for uncalcified red algae, and 0.01% for nongenictilate coralline algae) and lack of large grazers suggest that light controls the lower distributional limits. The ubiquitous distribution, perennial nature, and similar lower depth limits of deep-water macroalgal assemblages at all sites suggest that these assemblages are a common persistent part of the benthic biota in this region., Cited By (since 1996):26 Seaweeds, CODEN: JPYLA, ,
Author: Spalding, Foster, Heine
Date: 2003-01-01T00:00:00Z

Title: Using in situ substratum sterilization and fluorescence microscopy in studies of microscopic stages of marine macroalgae,
Description: The methods currently used for examining the relative contribution of microscopic stages to the persistence of natural populations of marine macroalgae can be inappropriate for use in subtidal habitats. Also, because of their microscopic size, direct examination and obtaining an estimate of recruitment, growth and mortality of these stages in the field is difficult. A method of removing microscopic algal stages from natural rock surfaces using watertight tents and water-soluble chemicals is presented. Also discussed is the use of a previously described method of fluorescent labelling these microscopic stages that, when examined under UV light, allows for their precise identification and growth to be determined. Together, these methods can be effective in examining the ecology of algal microscopic stages in the field., Cited By (since 1996):1, Seaweeds, CODEN: HYDRB, ,
Author: Edwards
Date: 1999-01-01T00:00:00Z

Title: Effects of climate change on global seaweed communities,
Description: Seaweeds are ecologically important primary producers, competitors, and ecosystem engineers that play a central role in coastal habitats ranging from kelp forests to coral reefs. Although seaweeds are known to be vulnerable to physical and chemical changes in the marine environment, the impacts of ongoing and future anthropogenic climate change in seaweed-dominated ecosystems remain poorly understood. In this review, we describe the ways in which changes in the environment directly affect seaweeds in terms of their physiology, growth, reproduction, and survival. We consider the extent to which seaweed species may be able to respond to these changes via adaptation or migration. We also examine the extensive reshuffling of communities that is occurring as the ecological balance between competing species changes, and as top-down control by herbivores becomes stronger or weaker. Finally, we delve into some of the ecosystem-level responses to these changes, including changes in primary productivity, diversity, and resilience. Although there are several key areas in which ecological insight is lacking, we suggest that reasonable climate-related hypotheses can be developed and tested based on current information. By strategically prioritizing research in the areas of complex environmental variation, multiple stressor effects, evolutionary adaptation, and population, community, and ecosystem-level responses, we can rapidly build upon our current understanding of seaweed biology and climate change ecology to more effectively conserve and manage coastal ecosystems. © 2012 Phycological Society of America., Cited By (since 1996):8, Seaweeds, CODEN: JPYLA, ,
Author: Harley, Anderson, Demes, Jorve, Kordas, Coyle, Graham
Date: 2012-01-01T00:00:00Z

Title: Arrested development of giant kelp (Macrocystis pyrifera, Phaeophyceae) embryonic sporophytes: A mechanism for delayed recruitment in perennial kelps?
Description: Delayed recruitment of microscopic stages in respouse to cyclical cues is critical to the population dynamics of many annual and seasonally reproducing perennial seaweeds. Microscopic stages may play a similar role in continuously reproducing perennials in which adult sporophytes are subject to episodic mortality, if they can respond directly to the unpredictable onset and relaxation of unfavorable conditions. We experimentally evaluated the potential for temporary reduction in limiting resources (light, nutrients) to directly delay recruitment of giant kelp (Macrocystis pyrifera (L.) C.A. Agardh) gametophytes and embryonic sporophytes. Laboratory cultures were subjected to limiting conditions of light and nutrients for 1 month and then exposed to non-limiting conditions for 10 days. Gametophytes in all treatments failed to recruit to sporophytes after 2 weeks, suggesting they are not a source of delayed recruitment in giant kelp. Sporophytes in light-limited treatments, however, survived and grew significantly slower than non-light-limited controls. When stimulated with light, light-limited sporophytes grew from 2 to >10 times faster than unstimulated controls depending on nutrient availability. These results suggest that limiting resources can delay recruitment of embryonic giant kelp sporophytes for at least 1 month. Flexible timing of recruitment from embryonic sporophytes may enhance persistence of continuously reproducing perennial species when macroscopic adults are subject to episodic large-scale removals., Cited By (since 1996):24, Seaweeds, CODEN: JPYLA
Author: Kinlan, Graham, Sala, Dayton
Date: 2003-01-01T00:00:00Z

Title: Loss of predators and the collapse of southern California kelp forests (?): Alternatives, explanations and generalizations,
Description: It is increasingly argued that human-induced alterations to food webs have resulted in the degradation of coastal ecosystems and even their "collapse." We examined the evidence for this argument for Macrocystis pyrifera (giant kelp) forests in southern California. Others have concluded that forests in this region collapsed between 1950 and 1970 as a result of sea urchin grazing driven by overfishing of sea urchin predators (sheephead wrasse and spiny lobsters) and competitors (abalone), and that the kelp forests recovered but are currently sustained as a result of a commercial sea urchin fishery that began in the early 1970s. Our examination of the historical record, primary publications, and previously unpublished data showed that there was no widespread decline in the region between 1950 and 1970, but there were localised declines in mainland kelp forests near the rapidly growing cities of Los Angeles and San Diego. The preponderance of evidence indicates that kelp losses were caused primarily by large increases in contaminated sewage discharged into coastal waters, sedimentation from coastal development, and the 1957-1959 El Niño. Increases in active sea urchin foraging were most likely a secondary effect following dwindling food resources. The forests recovered when sewage treatment improved and sewage outfalls were relocated. The effects of fisheries were explored by correlation analysis between kelp canopy cover and commercial sea urchin landings, and among fisheries landings for sea urchins, abalone, sheephead and lobster. These correlations were generally insignificant, but were often confounded by differences in the spatial scale over which the data were collected as well as factors other than simple abundance that affect the fisheries. However, where area-specific data were available, the landings of sea urchins generally tracked kelp abundance, most likely because roe (gonad) development is directly related to food availability. A literature review showed that although sheephead and lobsters may control sea urchin abundance at small spatial scales within some sites, there is little evidence they do so over large areas. That abalone and sea urchins compete, such that sea urchins increased as a result of abalone harvesting, is largely conjecture based on their similar habitat and food utilization. This study shows that kelp forests in southern California did not collapse, and that declines in some coastal sites were caused primarily by degradation of water quality, increased sedimentation and contamination, and unfavorable oceanographic conditions. We conclude that management by species' protection or reserves will not be effective if poor habitat quality impacts the ability of giant kelp to survive and thrive. © 2010 Elsevier B.V., Cited By (since 1996):20, Seaweeds, CODEN: JEMBA, ,
Author: Foster, Schiel
Date: 2010-01-01T00:00:00Z

Title: Coupling propagule output to supply at the edge and interior of a giant kelp forest
Description: Propagule dispersal is fundamental in regulating the strength of demographic and genetic interactions between individuals both within and among populations. I studied spatiotemporal variability in propagule (zoospore) supply of a continuously reproducing seaweed, giant kelp Macrocystis pyrifera, to examine: (1) the extent to which local zoospore production is coupled to (correlated with) temporal variability in zoospore supply; and (2) spatial variability in the strength of such coupling. Macrocystis pyrifera planktonic zoospores were quantified from seawater samples pumped on numerous dates in 1999 from just above the substratum at various sites in the Point Loma kelp forest, southern California, USA. Zoospore collections were made at a site in the forest interior approximately three times per month from late February through mid-November. Sample collection overlapped with complete demographic surveys of the local population (100 m2) to determine local reproductive output. Temporal variability in zoospore supply was strongly correlated with relative changes in the density .and size structure of local reproductive adult sporophytes; 76% of variability in zoospore supply was explained by local reproductive output. This tight coupling between zoospore supply and local reproduction appeared to be driven by low-displacement, oscillating currents in the forest interior due to the cumulative drag of adult sporophytes, which kept zoospores close to their release site. High coupling between zoospore supply and local reproduction was validated at two additional interior sites separated by 1 km; 78% of variability in zoospore supply was explained by local reproductive output at these sites. Due to lower sporophyte densities, however, the forest edges experienced rapid, unidirectional currents that appeared to transport zoospores far from their release site, effectively decoupling zoospore supply from local reproduction; only 38% of variability in zoospore supply was explained by local reproductive output at these sites. The results suggest that the size of and location within kelp populations is an important determinant of the importance of local reproduction to zoospore supply due to the effects of flow modification by kelp canopies on zoospore dispersal., Cited By (since 1996):27 Seaweeds, CODEN: ECOLA
Author: Graham

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