Examining the bank of microscopic stages in kelps using culturing and barcoding (original) (raw)
Related papers
Journal of Phycology, 2003
Delayed recruitment of microscopic stages in response 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 nonlimiting 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 Ͼ 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.
Colonization in Artificial Seaweed Substrates: Two Locations, One Year
Diversity
Artificial substrates have been implemented to overcome the problems associated with quantitative sampling of marine epifaunal assemblages. These substrates provide artificial habitats that mimic natural habitat features, thereby standardizing the sampling effort and enabling direct comparisons among different sites and studies. This paper explores the potential of the “Artificial Seaweed Monitoring System” (ASMS) sampling methodology to evaluate the natural variability of assemblages along a coastline of more than 200 km, by describing the succession of the ASMS’ associated macrofauna at two Rías of the Galician Coast (NW Iberian Peninsula) after 3, 6, 9, and 12 months after deployment. The results show that macrofauna assemblages harbored by ASMS differ between locations for every type of data. The results also support the hypothesis that succession in benthic communities is not a linear process, but rather a mixture of different successional stages. The use of the ASMS is proved ...
Trends in Plant Science, 2006
Teaser: A letter on the evolution of trends in seaweed research with respect to the development of technology and generation of knowledge, as well as difficulties and future perspectives in seaweed research.
Helgoländer Meeresuntersuchungen, 1987
An overview of the primary approaches to seaweed biogeography is provided in light of the development of vicariance biogeography. Each approach is discussed with particular regard to the extent to which the methods and objectives are compatible with vicafiance. Ecological biogeography is considered an offshoot of ecology and physiology and is more appropriate in determining current distributions of organisms and aspects of physiological ecology rather than the spedation history of monophyletic groups. The R/P quotient of Feldmann and distribution of algal life-forms do not fall within the aegis of vicariance and are considered useful only in a descriptive sense. The examination of seaweed spans propounded by Pielou is considered flawed because of the lack of dependence on monophyletic groups. The floristic school of analysis of many seaweed biogeographers is analagous to the panhiogeography of Croizat, and provides the basis for the more concrete phylogenetic hypotheses that are the basis for vicariance analysis. The latter is considered the best methodology for studying the relationship between patterns of cladogenesis and the distribution of constituent taxa.
2012
delivered post Congress at the International Society for Applied Phycology—ISAP 2011 in Halifax, and now on the eve of the Asia-Pacific Conference on Algal Biotechnology to be hosted in Adelaide. If you have somehow missed this information or the deadline has crept up on you, APCAB 2012 is still open to registration, however you only have a short time to make up your mind: www.sapmea.asn.au/apcab2012
FUNCTIONAL-MORPHOLOGY OF INTERTIDAL SEAWEEDS - ADAPTIVE SIGNIFICANCE OF AGGREGATE VS SOLITARY FORMS
Marine Ecology-Progress Series, 1984
Many intertidal seaweeds show a tremendous gradient of morphological form ranging from spatially separated thalli, to thalli that are aggregated into dense turfs. Aggregation of seaweeds into turfs decreases productivity per g organic weight due to crowding of thalli but increases resistance to desiccation. The intertidal distribution of the turf growth form is correlated with the intensity of desiccation stress. Also turfs transplanted into tide pools developed the non-turf morphology, while non-turfs transplanted to emergent substrate either developed the turf form or died. The turf growth form is energetically expensive; apparent productivity of turfs was 23 to 48 % less than that of individuals. Increasing light and nutrients available to turfs by separating the thalli increased apparent productivity by 36 to 113 %. We tested the hypothesis that these turfs minimize energetic costs of this aggregated growth form through the spatial partitioning of photosynthetic and respirative activity. The lower portions of turfs showed less apparent photosynthesis than the upper portions (reductions of 37 to 85 %); however, this spatial partitioning was also found in the individual forms (37 to 63 % reductions) of these relatively simple seaweeds. Spatial differentiation of respiration was similar in turfs and nonturfs. The seaweeds, examined are able to alter the extent of thalli compaction in accordance with varying levels of environmental stress. This phenotypic plasticity allows seaweeds to adopt morphological features that maximize fitness in a wide variety of habitats without being developmentally committed.
Succession of Seaweeds on Experimental Plates Immersed during Different Seasons in Tosa Bay, Japan
Botanica Marina, 1998
A study was undertaken of the seaweeds settling on experimental plates attached every two months from April 1993 to February 1994 to artificial reefs, which were placed in an Ecklonia-Sargassum community on the gravel bottom about 7m deep in Tosa Bay, Kochi Prefecture, Japan. The dominant species on the experimental plates were Sphacelaria sp., Zonaria diesingiana, Sargassum spp., Gelidium spp., Peyssonelia sp. and several species of Melobesioideae. The pattern of succession of the dominant species and the degree of domination were determined by the month of plate immersion. Irrespective of the time of immersion, the dominant species in the early stages were Melobesioideae. Within three months following placement of the plates, species of Melobesioideae dominated with coverage of approximately 80% on the plates placed in April, June and August. The plates placed in October, December and February showed coverage of approximately 30%. Every plate, except those placed in August, was dominated by Sargassum spp. within one year, but the time required for Sargassum domination was shorter on the plates placed in winter than in the other seasons. These results indicate that successional series and steps are affected by the season of substrata placement.
The Functional Morphology of Turf-Forming Seaweeds: Persistence in Stressful Marine Habitats
Ecology, 1981
Many seaweeds that occur in physically stressful habitats or habitats subject to moderate herbivory grow as colonial turfs rather than as spatially separated individuals. The turf growth form is energetically expensive (the net production per gram ash free dry mass of turfs being 33-61% lower than that of individuals), but turfs suffer less physiological damage during desiccating low tides and lose less biomass to herbivores. The upper portions of turf-forming species show significantly greater rates of apparent photosynthesi, and dark respiration than do the lower portions. This spatial partitioning of photosynthetic activity decreases the energetic cost of the turf arrangement and may allow basal portions to function as persistent resting stages during periods of adverse conditions when uprights cannot be maintained, Turf-forming species are specialized for areas that are subject to moderate grazing pressure and physical stresses, They are dependent upon these factors to prevent their competitive exclusion by more productive, but less resistant, seaweeds. Damage to apical portions causes increased branching that results in a more tightly compacted turf. Algae that regenerate in this way can adjust their growth form in accordance with varying levels of disturbance encountered in different habitats and thus incur the minimal cost consistent with survival in that area.
An Experimental Evaluation of Density and Plant Size in Two Large Brown Seaweeds
Journal of Phycology, 1998
The effects of density on the growth rate and survival of individual plants as well as changes in population structure (hierarchy) and biomass accumulation (self-thinning) were experimentally evaluated in two brown macroalgae. Laminaria digitata (Hudson) Lamouroux and Fucus serratus Linnaeus populations were constructed at five (650-5156 plants•m Ϫ2) and four densities (650-2668 plants•m Ϫ2), respectively, and were cultivated in tanks. The relative growth rates and survivorship of individuals and the populations' biomass and density (estimated dry mass) were periodically measured. To investigate how plant population size hierarchies influence conspecifics, single density populations of L. digitata were constructed of up to three sizes of plants in equal proportions, and these parts of the populations were compared through time with plants of the three sizes grown singly. At higher density, L. digitata plants grew more slowly, while F. serratus populations showed a similar trend that was never statistically significant. Survival of plants of both species was lower at high densities, and mortality selectively removed smaller plants. Plants of both species exhibited zero growth rates before death, when parts of the fronds were lost, but meristems (apical in F. serratus, at the base of the frond in L. digitata) were preserved until the death of the plant. All singly grown L. digitata plants survived, but survivorship was low in the fractions of small plants in mixedsize populations compared with that of the largest size plant fractions. Small L. digitata plants grew relatively faster than did large ones singly, but in mixed-size populations, small plants grew relatively slowly. Plant sizes became progressively more unequal (Gini and skewness coefficients) until self-thinning started reducing the size variability. The seaweeds followed self-thinning (density-biomass) trajectories predicted by the self-thinning ''rule'', and self-thinning appeared to be seasonal-rather than species-dependent, as it occurred at a time of year when ambient light levels start to fall in the Isle of Man. Culture studies of this kind, despite their considerable potential, are a tool as yet underexploited by marine ecologists as a means of assessing intraspecific competitive interaction among seaweeds.