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Mario Edding - One of the best experts on this subject based on the ideXlab platform.
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increased temperature but not pco2 levels affect early developmental and reproductive traits of the economically important habitat forming kelp Lessonia trabeculata
Marine Pollution Bulletin, 2018Co-Authors: Claudio P Gonzalez, Mario Edding, Rodrigo Torres, Patricio H ManriquezAbstract:Abstract The effects of ocean warming and ocean acidification on developmental and reproductive traits of Lessonia trabeculata were evaluated. Meiospores were cultured for 35 days in an experimental mesocosm where temperature (~15 and 19 °C) and partial CO2 pressure (pCO2, ~400 and 1300 μatm) were controlled. The results indicate that germination was reduced at 19 °C, whereas the increase of pCO2 only had effects at 15 °C. Likewise, the increase in temperature significantly affected the vegetative growth of female gametophytes. Sex ratio was not affected significantly by any of the variables studied. Fertility and reproductive success decreased by about 50% at 19 °C. The pCO2 levels had no significant effects on most early developmental traits. The results suggest that ocean warming or periodic warming events (e.g. an El Nino event) might affect the recruiting capacity of this or other similar species by affecting their early developmental stages.
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early life stages of the south pacific kelps Lessonia nigrescens and Lessonia trabeculata laminariales phaeophyceae show recovery capacity following exposure to uv radiation
Phycologia, 2007Co-Authors: Fadia Tala, Karina Veliz, Ivan Gomez, Mario EddingAbstract:Abstract This study examined the recovery capacity of early life stages of the South Pacific kelps Lessonia nigrescens and Lessonia trabeculata after exposure to artificial ultraviolet radiation (UV-B280–315 nm, UV-A315–400 nm). Spores (3 h postrelease) were exposed to different UV doses applied as daily pulses (0.5, 1, 2, 3, 4 h) during 6 days. Afterwards cultures were kept under PAR condition and fertility of gametophytes and formation of sporophytes measured up to day 45 (for L. nigrescens) and 65 (for L. trabeculata). The irradiation with UV-B radiation for 6 days strongly impaired spore germination: at biologically effective UV doses (BEDCaldwell > 2 kJ m−2; pulses > 2 h per day), complete mortality of the spores was observed. In contrast, spores irradiated with UV-A retained a germination capacity close to 80 and 70% under high doses (75 kJ m−2; 4 h per day). The surviving spores from both treatments exhibited a recovery during their further development as the fertility of gametophytes and formation...
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first estimates of productivity in Lessonia trabeculata and Lessonia nigrescens phaeophyceae laminariales from the southeast pacific
Phycological Research, 2007Co-Authors: Fadia Tala, Mario EddingAbstract:SUMMARY Lessonia is the main Laminariales found along the southeast Pacific coast. Lessonia nigrescens Bory de Saint-Vincent in the intertidal and Lessonia trabeculata Villouta et Santelices in the subtidal, are the most important habitat constructors in rocky coastal communities in northern and central Chile. In both species, the seasonal production and erosion of distal tissue were estimated in biomass units using the Area of Constant Biomass Model that combined the individual blade elongation, obtained with the traditional hole-punching method, with the blade length and biomass distribution along the blade. In austral late spring (December 96) and autumn (May 97), blade production and erosion were transformed to the level of population from standing stock measurements (number and biomass of blades and plants per substrate area), considering that previous blade weight analysis showed the highest and lowest values at these times, as well as the population parameter extremes that were expected to occur. Both species displayed a seasonal pattern, with a production increase in later winter and spring and decrease towards the end of summer that coincided with higher distal tissue erosion. At the level of individual blades, Lessonia trabeculata showed higher mean production (0.026 g dw d−1) and erosion (0.01 g dw d−1) than L. nigrescens (production 0.01 g dw d−1 and loss 0.002 g dw d−1). The standing stocks, with respect to density and biomass, were similar in spring and autumn for both populations. Nevertheless, the net productivity (production minus erosion) of the intertidal L. nigrescens showed greater values due to the greater density of blades (2112 ± 1360 (SE) blades m−2) compared with the subtidal L. trabeculata (527 ± 151 (SE) blades m−2). Spring net productivities of 42 g dw m−2d−1 (254 g ww m−2d−1; 11.46 gC m−2d−1) for L. nigrescens and 11 g dw m−2 d−1 (64 g ww m−2 d−1; 2.46 gC m−2d−1) for L. trabeculata were estimated. A preliminary model of production and biomass fate for Lessonia populations is proposed.
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artificial induction of sporulation in Lessonia phaeophyta laminariales
Journal of Applied Phycology, 1998Co-Authors: Erika Fonck, Fadia Tala, Mariela Venegas, Mario EddingAbstract:The effects of three physical variables on sporulation, germination and gametophyte survival were evaluated on two species of Laminariales at Coquimbo, Chile (30° S). Parameters were evaluated using reproductive fronds of Lessonia nigrescens Bory and Lessonia trabeculata Villouta and Santelices with treatment variables including type of pre-rinse, dehydration, and temperature. Although the response was slightly different in the two species, it was found that pre-rinsing the blades with tap water produced marked sporulation without affecting germination and survival. Minor effects were observed with other variables, including positive effects of lower temperature and negative effects of longer dehydration periods. The high commercial value of these two species has promoted much interest in their artificial propagation in Chile.
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a comparison between two populations of Lessonia trabeculata phaeophyta laminariales microscopic stages
Hydrobiologia, 1993Co-Authors: Mario Edding, Erika Fonck, Mariela Venegas, Patricia Orrego, Juan MacchiavelloAbstract:Lessonia trabeculata is the most important brown seaweed in northern Chilean subtidal environments. It usually grows in areas with high to moderately high water movement, and only occasionally in sheltered habitats. These different hydrodynamic environments produce morphologically and physiologically distinct plants. The purpose of this study was to determine probable differences in reproductive features between two L. trabeculata populations exposed to different water movement intensities. The zoospore production, settlement, germination, gametophyte fertility and survival were studied.
Juan A Correa - One of the best experts on this subject based on the ideXlab platform.
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modulatory effect of the exudates released by the brown kelp Lessonia spicata on the toxicity of copper in early developmental stages of ecologically related organisms
Environmental Science and Pollution Research, 2017Co-Authors: Jessica Beltran, Santiago Andrade, Alexandre Fellous, Francisco Vidalramirez, Ricardo Calderon, Juan A CorreaAbstract:Lessonia spicata is a key dominant species along the Pacific coast of South America, providing a habitat for many organisms. However, this role can be affected by abiotic stress, such as metals. To counteract the toxic effect, L. spicata, among other seaweeds, releases exudates that bind metals. In this study, tolerances to copper of organisms related to the kelp forest (spores of Ulva lactuca (Chlorophyceae) and L. spicata (Phaeophyceae) and Zoea I of Taliepus dentatus (Milne-Edwards, Crustacea)) were studied; then, exudates are assessed by their protective effect. Exudates increase the 48-h 50% effective concentration (EC50) of the germination of spores from 8 to 23 μg Cu L−1 for U. lactuca and from 119 to 213 μg Cu L−1 for L. spicata and the survival of the larvae Zoea I 48-h 50% of lethal concentration (LC50) from 144 to 249 μg Cu L−1. Results indicated that exudates had a protective effect. Each species is specifically sensitive to copper. Crab larvae Zoea I were able to support higher doses, and exposure before hatching increased their tolerance.
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identification of cryptic species in the Lessonia nigrescens complex phaeophyceae laminariales 1
Journal of Phycology, 2012Co-Authors: Alejandra V Gonzalez, Jessica Beltran, Luciano Hiriartbertrand, Veronica Flores, Bruno De Reviers, Juan A Correa, Bernabe SantelicesAbstract:The kelp Lessonia nigrescens Bory is the most ecologically and economically important seaweed in rocky intertidal and shallow subtidal habitats along the temperate Pacific South American coasts. Recent molecular studies suggest the existence of two lineages, one (northern lineage) from 17° S to 30° S and a second (central lineage) from 29° S to 41° S. To identify and name these lineages we performed morphological, nomenclatural and field studies. Four external and three internal anatomical traits permitted a morphological separation of the two lineages. The internal structure of both lineages was different from the isolectotype of Lessonia nigrescens. It is therefore concluded that the name Lessonia nigrescens should not be used for the Chilean material. Chordaria spicata Suhr appears as the oldest available name for the central lineage, while Lessonia berteroana Montagne is the oldest name for the northern lineage. In both cases, the type material consisted of small-sized, apical branches of larger plants. The new combination Lessonia spicata (Suhr) Santelices is proposed for the central lineage and we reinstate Lessonia berteroana for the northern lineage. Laminaria scissa Suhr is reduced to synonym of L. spicata. Representative specimens of Lessonia nigrescens were not found during new visits to its type locality in Cape Horn and along Chile. Future studies should verify the status of this species.
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laminariocolax sp phaeophyceae associated with gall developments in Lessonia nigrescens phaeophyceae
Journal of Phycology, 2009Co-Authors: Daniela Thomas, Jessica Beltran, Veronica Flores, Loretto Contreras, Edda Bollmann, Juan A CorreaAbstract:As part of a long-term study on the biology and ecology of the intertidal kelp Lessonia nigrescens Bory, we report on the occurrence of gall development on this alga, identified the possible causal agent, and assessed the extent of the phenomenon in two wild stands of the host. Our results showed that galls affecting natural populations of L. nigrescens were associated with the infection by a filamentous brown algal endophyte of the genus Laminariocolax. Assignment to Laminariocolax of the endophytes isolated from cultured gall tissue was based on the (i) high internal transcribed spacer 1 (ITS1) sequence similarity and phylogenetic relationship between the Chilean isolates and several species of the genus Laminariocolax endophytic in other kelps, (ii) reproductive and vegetative features of the endophyte in culture, and (iii) anatomical agreement of fully developed galls of Lessonia with those described for other kelp galls caused by endophytic members of Laminariocolax. Unequivocal identification at the species level of the endophytes infecting Lessonia, however, awaits further studies.
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phylogeographic analyses of the 30 s south east pacific biogeographic transition zone establish the occurrence of a sharp genetic discontinuity in the kelp Lessonia nigrescens vicariance or parapatry
Molecular Phylogenetics and Evolution, 2009Co-Authors: Florence Tellier, Juan A Correa, Sylvain Faugeron, Andres P Meynard, Myriam ValeroAbstract:Abstract Phylogeographic studies are lacking in the Southern Hemisphere, and in particular in the south-eastern Pacific. To infer the possible scenario for the debated biogeographic transition zone located at 30–33°S along the Chilean coast, we investigated whether there is a concordance between the phylogeographic pattern and the biogeographic transition in the intertidal kelp Lessonia nigrescens whose distribution is continuous across this transition zone. Using a combination of four makers located in the three genomic compartments (chloroplast, mitochondria and nucleus), we showed the presence of two main divergent lineages, possibly cryptic species. There was an exact match of the phylogeographic break with the 30°S biogeographic transition zone, suggesting a common origin. The combined information given by the multilocus approach and by the population analysis suggested the occurrence of a budding speciation, with a northward range expansion.
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Phylogeographic analyses of the 30°S south-east Pacific biogeographic transition zone establish the occurrence of a sharp genetic discontinuity in the kelp Lessonia nigrescens: Vicariance or parapatry?
Molecular Phylogenetics and Evolution, 2009Co-Authors: Florence Tellier, Juan A Correa, Sylvain Faugeron, Andres P Meynard, Myriam ValeroAbstract:Abstract Phylogeographic studies are lacking in the Southern Hemisphere, and in particular in the south-eastern Pacific. To infer the possible scenario for the debated biogeographic transition zone located at 30–33°S along the Chilean coast, we investigated whether there is a concordance between the phylogeographic pattern and the biogeographic transition in the intertidal kelp Lessonia nigrescens whose distribution is continuous across this transition zone. Using a combination of four makers located in the three genomic compartments (chloroplast, mitochondria and nucleus), we showed the presence of two main divergent lineages, possibly cryptic species. There was an exact match of the phylogeographic break with the 30°S biogeographic transition zone, suggesting a common origin. The combined information given by the multilocus approach and by the population analysis suggested the occurrence of a budding speciation, with a northward range expansion.
Julio A Vasquez - One of the best experts on this subject based on the ideXlab platform.
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monitoring the sustainability of Lessonia nigrescens laminariales phaeophyceae in northern chile under strong harvest pressure
Journal of Applied Phycology, 2014Co-Authors: J Alonso M Vega, Bernardo R Broitman, Julio A VasquezAbstract:In the last decade, exploitation of Lessonia nigrescens in northern Chile has been carried out using the best practices agreed upon by consensus between fishermen, industry, government, and scientists. These practices focus on the selective harvest of sporophytes to allow the maintenance of a reproductive stock, facilitating recruitment and minimizing grazing of benthic herbivores. To improve coverage and accessibility, enforcement of administration measures along the northern coast of Chile requires ecological indicators to monitor the sustainability of Lessonia kelps. Over 2 years, density, biomass, recruitment, and size structure of Lessonia were sampled seasonally in coastal areas with different regimens of harvesting administration as follows: (1) Management Areas for Exploitation of Benthic Resources (MAEBR), (2) Open Access Areas (OAA), and (3) Marine Protected Areas without human intervention. The use of demographic parameters as ecological indicators allows discrimination between kelp beds where good harvesting practices have been applied by users (MAEBR), and areas where management recommendations have not been put in practice (OAA). The ecological indicators reinforced the concept of co-management in MAEBR as a viable harvesting administration system along the Chilean coast, and indicated a high-harvesting pressure in OAA. Moreover, together with other harvesting parameters, they could be useful to justify the application of other administration strategies, such as quotas or bans.
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the Lessonia nigrescens fishery in northern chile how you harvest is more important than how much you harvest
Journal of Applied Phycology, 2012Co-Authors: Julio A Vasquez, Nicole Piaget, J Alonso M VegaAbstract:In Chile, management of natural resources usually starts right before its imminent collapse or after evident declination. In the northern area of the country, the fishery of brown seaweeds has an enormous social, ecological, and economical importance. More than 11,000 people depend directly or indirectly on the collection and harvesting of this resource. Ecologically, kelps constitute areas for food, reproduction, and refuge for hundreds of invertebrates and fish species. Economically, landings up to 300,000 dry tons per year represent close to US $60 million for the industry. Until 2002, the Chilean brown seaweed fishery was mainly sustained by natural mortality, where plants cast ashore were collected by artisanal fishermen. Since then, three brown seaweed species of economic importance (Lessonia nigrescens, Lessonia trabeculata, and Macrocystis pyrifera) have been intensively harvested in coastal areas between 18° and 32° S. To manage kelp populations along the northern Chilean coast, regulations have been based on the principle “how you harvest is more important than how much you harvest”. This exploitation strategy has been adopted in consensus between fishermen, industries, governmental entities, and scientists. Since L. nigrescens represents more than 70% of total brown seaweed landings, this study tests the effects of L. nigrescens harvesting on the following population variables: (1) abundance, (2) distribution, (3) juvenile recruitment, (4) plant morphology, (5) frequency of reproductive plants, and (6) biodiversity of the macroinvertebrate community associated to kelp holdfasts. Our results show that, despite the enormous harvesting pressure on Lessonia density and biomass, the associated macroinvertebrate richness has been maintained, due to normal plant growth and high recruitment all year round.
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Production, use and fate of Chilean brown seaweeds: re-sources for a sustainable fishery
Journal of Applied Phycology, 2008Co-Authors: Julio A VasquezAbstract:Chile is an important producer of brown seaweeds representing 10% of world supply. Landings of Chilean kelp fluctuated between 40,000 t.year^−1 in the early ‘80s to 250,000 t.year^−1 more recently. Commercialized algae come from natural populations and no mass-cultures of involved species have been established. Four species of brown algae are commercially collected in the country: Lessonia trabeculata , L. nigrescens , Macrocystis pyrifera and M. integrifolia . Since 2000, the demand of alginate sources and food for cultivated abalones dramatically raised the harvesting of these species. Direct evaluations of Lessonia spp. and Macrocystis standing-stocks were made along 700 km of coast in northern Chile. Lessonia spp. estimated populations exceed 900,000 t, whereas M. integrifolia does not exceed 300 t. The insights provided indicate that sustainability of Chilean kelp subjected to intense harvesting would require management programs including the following bio-ecological recommendations: (1) to harvest the entire plant including the holdfast; (2) to harvest plants larger than 20 cm in diameter; (3) to harvest plants sparsely, selecting mayor specimens; (4) rotation of harvesting areas; and (5) for Macrocystis , to cut the canopy 1–2 m from the surface. They must be implemented in a National Program of Kelp Management, elaborated by government, scientists, fisherman, and industry.
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aspects of the reproductive phenology of Lessonia trabeculata laminariales phaeophyceae from three populations in northern chile
New Zealand Journal of Marine and Freshwater Research, 2004Co-Authors: Fadia Tala, Mario E Edding, Julio A VasquezAbstract:Abstract Lessonia trabeculata is a brown seaweed inhabiting the rocky subtidal zone along the coast of central and northern Chile, where it is the dominant kelp, and an important species in community structure. Morphological and reproductive aspects of this alga are dependent on environmental conditions and geographic distribution, and the present study gives data on its reproductive periodicity. The reproductive phenology for three populations from northern Chile (29–30°S) was evaluated by means of seasonal examination of morphological and reproductive characteristics of both macroscopic sporophytes and microscopic gametophytes. Comparative laboratory cultures of spores were made to determine seasonal differences in their capacity to produce viable plants. This species is perennial, and demonstrates year‐round presence of reproductive tissues, although showing variation in reproductive phenology over time and among populations. The size of blades increases in spring and summer, whereas its reproductive p...
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effects of copper pollution on the ultrastructure of Lessonia spp
Hydrobiologia, 1999Co-Authors: Patricia I Leonardi, Julio A VasquezAbstract:Plants of Lessonia trabeculata and L. nigrescens were studied by transmission electron microscopy in order to evaluate ultrastructural level changes in response to copper exposure. Samples of fronds, stipes, and holdfasts were collected from areas with and without copper mining discharges. Changes in cell ultrastructure observed in Lessonia trabeculata were related to copper concentrations in seawater, seaweeds and extracted alginates. The results strongly suggest that tolerance or adaptation of Lessonia to high concentrations of copper is the capacity of different plant tissues to accumulate copper as precipitates, primarily at two levels: the cell wall and periplasmalemmal space, with the vacuolar system being a third site.
Bernabe Santelices - One of the best experts on this subject based on the ideXlab platform.
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frequency of chimerism in populations of the kelp Lessonia spicata in central chile
PLOS ONE, 2017Co-Authors: Alejandra V Gonzalez, Bernabe SantelicesAbstract:: Chimerism occurs when two genetically distinct conspecific individuals fuse together generating a single entity. Coalescence and chimerism in red seaweeds has been positively related to an increase in body size, and the consequent reduction in susceptibility to mortality factors, thus increasing survival, reproductive potential and tolerance to stress in contrast to genetically homogeneous organisms. In addition, they showed that a particular pattern of post-fusion growth maintains higher genetic diversity and chimerism in the holdfast but homogenous axes. In Chilean kelps (brown seaweeds), intraorganismal genetic heterogeneity (IGH) and holdfast coalescence has been described in previous research, but the extent of chimerism in wild populations and the patterns of distribution of the genetically heterogeneous thallus zone have scarcely been studied. Since kelps are under continuous harvesting, with enormous social, ecological and economic importance, natural chimerism can be considered a priceless in-situ reservoir of natural genetic resources and variability. In this study, we therefore examined the frequency of IGH and chimerism in three harvested populations of Lessonia spicata. We then evaluated whether chimeric wild-type holdfasts show higher genetic diversity than erect axes (stipe and lamina) and explored the impact of this on the traditional estimation of genetic diversity at the population level. We found a high frequency of IGH (60-100%) and chimerism (33.3-86.7%), varying according to the studied population. We evidenced that chimerism occurs mostly in holdfasts, exhibiting heterogeneous tissues, whereas stipes and lamina were more homogeneous, generating a vertical gradient of allele and genotype abundance as well as divergence, constituting the first time "within- plant" genetic patterns have been reported in kelps. This is very different from the chimeric patterns described in land plants and animals. Finally, we evidenced that IGH affected genetic differentiation among populations, showed lower levels of FST index when we compared holdfast than lamina samples. In the light of this, future studies should evaluate the significance of chimeric holdfasts in their ability to increase kelps resilience, improve restoration and ecosystem service.
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morphological convergence in the inter holdfast coalescence process among kelp and kelp like seaweeds Lessonia macrocystis durvillaea
Phycologia, 2015Co-Authors: Alejandra V Gonzalez, Jessica Beltran, Veronica Flores, Bernabe SantelicesAbstract:In brown macroalgae, intraspecific holdfast coalescence has only been studied in two species of Lessonia (Lessonia spicata and Lessonia berteroana). In both species coalescence followed the same general pattern: once the connection between holdfasts was established, the contact areas showed significant cellular morphological modifications. Typical epidermal cells became polygonal and similar to cortical cells. In addition, coalescence involved the de novo formation of secondary plasmodesmata, establishing a direct cytoplasm connection within neighbouring cells, where dense materials, vacuoles and organelles can be observed. In the present study, we demonstrate intraspecific holdfast coalescence in two additional kelp species, Lessonia trabeculata and Macrocystis pyrifera, as well as in the kelp-like seaweed, Durvillaea antarctica. The process of holdfast fusions in these species is similar to that described previously and suggests that this is a generalized phenomenon among kelp and kelp-like brown algae....
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morphological ultrastructural and genetic characterization of coalescence in the intertidal and shallow subtidal kelps Lessonia spicata and l berteroana laminariales heterokontophyta
Journal of Applied Phycology, 2014Co-Authors: Alejandra V Gonzalez, Jessica Beltran, Veronica Flores, R Borraschavez, J A Vasquez, Bernabe SantelicesAbstract:Coalescing macroalgae may fuse with conspecifics, forming genetically heterogeneous entities known as chimera. This process has been shown in taxa from roughly half the red algal orders and in the Codium species, a green alga. Field observations indicate that common and dominant kelps along central Chile exhibit a fused holdfast. We evaluated whether such fusions are true coalescence processes in Lessonia spicata and Lessonia berteroana. To this end, we characterized the ultrastructural event involved in holdfast fusion in the laboratory. Additionally, coalescence in natural populations was quantified by measuring the frequency of individuals with genetically heterogenic stipes within the same holdfast. Results indicate that coalescence appears as a frequent process in laboratory, mostly restricted to intraspecific fusions. During fusion, the meristodermatic cells located in the contact area modify their morphology and reduce the number of plastids, mitochondria, and cell inclusions. The cell wall becomes much thinner and develops plasmodesmata, enhancing communication with equivalent cells of the other coalescencing individual. Stipe genotyping indicates that there is a widespread occurrence of chimerism in both species and genetic heterogeneity is increasing directly with the increasing number of stipes. The combination of results suggests that kelp frequently coalesce in the field, and the histological response observed approaches that of red algae. Since kelps are part of the dominant vegetation in low intertidal and shallow subtidal beds, the adaptive values of coalescence in these species should be evaluated. It is concluded that coalescence and chimerism are evolutionary convergent processes, occurring in all three major groups of seaweeds.
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identification of cryptic species in the Lessonia nigrescens complex phaeophyceae laminariales 1
Journal of Phycology, 2012Co-Authors: Alejandra V Gonzalez, Jessica Beltran, Luciano Hiriartbertrand, Veronica Flores, Bruno De Reviers, Juan A Correa, Bernabe SantelicesAbstract:The kelp Lessonia nigrescens Bory is the most ecologically and economically important seaweed in rocky intertidal and shallow subtidal habitats along the temperate Pacific South American coasts. Recent molecular studies suggest the existence of two lineages, one (northern lineage) from 17° S to 30° S and a second (central lineage) from 29° S to 41° S. To identify and name these lineages we performed morphological, nomenclatural and field studies. Four external and three internal anatomical traits permitted a morphological separation of the two lineages. The internal structure of both lineages was different from the isolectotype of Lessonia nigrescens. It is therefore concluded that the name Lessonia nigrescens should not be used for the Chilean material. Chordaria spicata Suhr appears as the oldest available name for the central lineage, while Lessonia berteroana Montagne is the oldest name for the northern lineage. In both cases, the type material consisted of small-sized, apical branches of larger plants. The new combination Lessonia spicata (Suhr) Santelices is proposed for the central lineage and we reinstate Lessonia berteroana for the northern lineage. Laminaria scissa Suhr is reduced to synonym of L. spicata. Representative specimens of Lessonia nigrescens were not found during new visits to its type locality in Cape Horn and along Chile. Future studies should verify the status of this species.
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selective mortality on haploid and diploid microscopic stages of Lessonia nigrescens bory phaeophyta laminariales
Journal of Experimental Marine Biology and Ecology, 1998Co-Authors: Enrique A Martinez, Bernabe SantelicesAbstract:Abstract In seaweeds, potential selective events on juveniles are particularly important because the highest mortality rates usually affect these microscopic stages rather than the macroscopic ones. This study evaluates the degree to which the mortality induced by herbivory and wave impact are selective on the size (mean and whole distribution) of haploid, gametophytic, and of diploid, early sporophytic stages of the intertidal kelp Lessonia nigrescens . In theory, in species with a complex life history, the potential effect of selective mortality on haploid and diploid individuals may range between two extremes. One of inhibition, where the same feature, conferring higher survival in one phase, may cause the opposite effect in the following phase. The other extreme is synergism, where selection operates similarly among the two alternating life history phases. Controlled experiments showed that herbivorous snails had a more significant negative impact on haploid gametophytes than on the slightly larger, diploid, sporophytes. Conversely, separate experiments showed that wave impact eliminated more efficiently the larger diploid plantules than the smaller haploid ones. Size selectivity by both mortality agents occurred only on the microscopic diploid stages, when plantule sizes were longer than 20 μm. Directionality of selection indicated that larger individuals, with more developed adhesive rhizoids, had higher survival rates. The directional selection on diploid plants is neither reinforced, or cancelled out, in the alternate haploid stages. Thus, no inhibitory or synergetic effects were observed for the directional selection of size between these two life history phases. These results suggest that, compared to organisms with direct life cycles, those having complex life histories, with independent phases, have at least one more restriction for the occurrence of evolutionary change. Namely, that of equivalent expression and response of involved traits on both alternate haploid and diploid phases to the same putative selective agents.
Fadia Tala - One of the best experts on this subject based on the ideXlab platform.
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species separation within the Lessonia nigrescens complex phaeophyceae laminariales is mirrored by ecophysiological traits
Botanica Marina, 2015Co-Authors: Kristina Koch, Florence Tellier, Fadia Tala, Martin Thiel, Wilhelm Hagen, Martin Graeve, Philipp Laeseke, Kai BischofAbstract:Lessonia nigrescens used to be an abundant kelp species along the Chilean coast, but recent molecular studies revealed the existence of a L. nigrescens species complex, which includes the two cryptic species Lessonia berteroana and Lessonia spicata. Since these species have different distributions (16°S-30°S for L. berteroana and 29°S-42°S for L. spicata), they experience differences in environmental conditions, such as solar irradiance, seawater temperature and air exposure during low tide. This study tested to what extent the genetic distinctness of each of the two species (identified by a mitochondrial marker (atp8/trnS)) is reflected by ecophysiological traits (total lipids, fatty acid composition, phlorotannins, pig- ments and variable chlorophyll a fluorescence of PSII) in response to the respective environmental conditions, prevailing along the latitudinal gradient. We studied algal individuals from eight populations (27°S-32°S, including the species overlapping zone). Phlorotannins, pigments and Chl a fluorescence of PSII were most crucial for species-specific adaptations at the respective growth sites, whereas changes in total lipids and fatty acid com- positions were negligible. Hence, species differentiation within the L. nigrescens complex is also manifested at the ecophysiological level. These findings may help to predict kelp responses towards future environmental changes.
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early life stages of the south pacific kelps Lessonia nigrescens and Lessonia trabeculata laminariales phaeophyceae show recovery capacity following exposure to uv radiation
Phycologia, 2007Co-Authors: Fadia Tala, Karina Veliz, Ivan Gomez, Mario EddingAbstract:Abstract This study examined the recovery capacity of early life stages of the South Pacific kelps Lessonia nigrescens and Lessonia trabeculata after exposure to artificial ultraviolet radiation (UV-B280–315 nm, UV-A315–400 nm). Spores (3 h postrelease) were exposed to different UV doses applied as daily pulses (0.5, 1, 2, 3, 4 h) during 6 days. Afterwards cultures were kept under PAR condition and fertility of gametophytes and formation of sporophytes measured up to day 45 (for L. nigrescens) and 65 (for L. trabeculata). The irradiation with UV-B radiation for 6 days strongly impaired spore germination: at biologically effective UV doses (BEDCaldwell > 2 kJ m−2; pulses > 2 h per day), complete mortality of the spores was observed. In contrast, spores irradiated with UV-A retained a germination capacity close to 80 and 70% under high doses (75 kJ m−2; 4 h per day). The surviving spores from both treatments exhibited a recovery during their further development as the fertility of gametophytes and formation...
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first estimates of productivity in Lessonia trabeculata and Lessonia nigrescens phaeophyceae laminariales from the southeast pacific
Phycological Research, 2007Co-Authors: Fadia Tala, Mario EddingAbstract:SUMMARY Lessonia is the main Laminariales found along the southeast Pacific coast. Lessonia nigrescens Bory de Saint-Vincent in the intertidal and Lessonia trabeculata Villouta et Santelices in the subtidal, are the most important habitat constructors in rocky coastal communities in northern and central Chile. In both species, the seasonal production and erosion of distal tissue were estimated in biomass units using the Area of Constant Biomass Model that combined the individual blade elongation, obtained with the traditional hole-punching method, with the blade length and biomass distribution along the blade. In austral late spring (December 96) and autumn (May 97), blade production and erosion were transformed to the level of population from standing stock measurements (number and biomass of blades and plants per substrate area), considering that previous blade weight analysis showed the highest and lowest values at these times, as well as the population parameter extremes that were expected to occur. Both species displayed a seasonal pattern, with a production increase in later winter and spring and decrease towards the end of summer that coincided with higher distal tissue erosion. At the level of individual blades, Lessonia trabeculata showed higher mean production (0.026 g dw d−1) and erosion (0.01 g dw d−1) than L. nigrescens (production 0.01 g dw d−1 and loss 0.002 g dw d−1). The standing stocks, with respect to density and biomass, were similar in spring and autumn for both populations. Nevertheless, the net productivity (production minus erosion) of the intertidal L. nigrescens showed greater values due to the greater density of blades (2112 ± 1360 (SE) blades m−2) compared with the subtidal L. trabeculata (527 ± 151 (SE) blades m−2). Spring net productivities of 42 g dw m−2d−1 (254 g ww m−2d−1; 11.46 gC m−2d−1) for L. nigrescens and 11 g dw m−2 d−1 (64 g ww m−2 d−1; 2.46 gC m−2d−1) for L. trabeculata were estimated. A preliminary model of production and biomass fate for Lessonia populations is proposed.
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growth and loss of distal tissue in blades of Lessonia nigrescens and Lessonia trabeculata laminariales
Aquatic Botany, 2005Co-Authors: Fadia Tala, Mario E EddingAbstract:Abstract Meristematic growth and loss of distal tissue from blades of two ecologically important species in the south-east Pacific, Lessonia nigrescens and Lessonia trabeculata , was evaluated during 1 year. Comparative growth was determined by a hole-punch method, loss of distal tissue from the blades was determined by subtracting final blade length (with loss) from expected blade lengths (without loss); growth and tissue loss were transformed to fresh biomass units for calculation of inter-algae differences. The results showed that blade elongation rate increased at the beginning of spring, and declined towards the end of summer, with mean values between 0.40 and 0.08 cm day −1 for L. nigrescens , and 0.65–0.17 cm day −1 for L. trabeculata . Loss of distal tissue varied seasonally when examined as length units for both species; with mean values between 0.24 and 0.10 cm day −1 for L. nigrescens , and 0.51–0.25 cm day −1 for L. trabeculata . Variations in fresh biomass units were only observed in Lessonia trabeculata , increasing in spring, with mean values to 0.13 g (fresh weight) day −1 . Annual growth and loss of distal tissue were higher in L. trabeculata (0.41 and 0.39 cm day −1 , respectively) than in L nigrescens (0.19 and 0.15 cm day −1 ). When growth and tissue loss were considered as fresh biomass, monthly gains significantly outweighed loss of distal tissue in both species, but parallel results based on length data followed a different trend. L. trabeculata released about 50% of its growth biomass as particulate organic matter, while the comparative value for L. nigrescens was about 20%.
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aspects of the reproductive phenology of Lessonia trabeculata laminariales phaeophyceae from three populations in northern chile
New Zealand Journal of Marine and Freshwater Research, 2004Co-Authors: Fadia Tala, Mario E Edding, Julio A VasquezAbstract:Abstract Lessonia trabeculata is a brown seaweed inhabiting the rocky subtidal zone along the coast of central and northern Chile, where it is the dominant kelp, and an important species in community structure. Morphological and reproductive aspects of this alga are dependent on environmental conditions and geographic distribution, and the present study gives data on its reproductive periodicity. The reproductive phenology for three populations from northern Chile (29–30°S) was evaluated by means of seasonal examination of morphological and reproductive characteristics of both macroscopic sporophytes and microscopic gametophytes. Comparative laboratory cultures of spores were made to determine seasonal differences in their capacity to produce viable plants. This species is perennial, and demonstrates year‐round presence of reproductive tissues, although showing variation in reproductive phenology over time and among populations. The size of blades increases in spring and summer, whereas its reproductive p...