Thallus Size Research Articles

Molecular determination of kleptoplast origins from the sea slug Plakobranchus ocellatus (Sacoglossa, Gastropoda) reveals cryptic bryopsidalean (Chlorophyta) diversity in the Hawaiian Islands.

The sacoglossan sea slug species complex Plakobranchus ocellatus is a common algivore throughout the tropical Pacific, including the Hawaiian Islands. Plakobranchusocellatus is kleptoplastic-it sequesters and retains algal chloroplasts-a characteristic that can be exploited to molecularly characterize diminutive bryopsidalean algae that are typically difficult to locate, collect, and identify. Previous DNA barcode analyses of both P.ocellatus and its kleptoplasts have been conducted primarily in the western Pacific and have only minimally sampled the most eastern populations in the Hawaiian Islands. Using two chloroplast markers, rbcL and tufA, kleptoplast samples from an Oahu population of P.ocellatus were amplified and cloned to identify their algal sources. Plakobranchusocellatus sequester chloroplasts from up to 11 bryopsidalean algal species, all but one being diminutive in thallus size. Notably, eight of the detected algal species were new records to the Hawaiian Islands. A sequestration preference study demonstrated that the O'ahu population of P.ocellatus preferentially sequesters chloroplasts from diminutive, epilithic taxa. Using coxI barcoding of P.ocellatus, we showed the O'ahu population to be part of a clade that includes sequences from the neighboring island Maui, Australia, and the Philippines. The use of P.ocellatus as a novel sampling tool allows the exploration of the green algal community diversity and composition at a fine scale.

The establishment of the non-native seaweed Polysiphonia morrowii in Northern Patagonia: Size of thallus and reproduction

A population of Polysiphonia morrowii, recently introduced in the South West Atlantic Ocean, was studied to determine the degree of its establishment. Monthly variations of: thallus size, proportion of life history phases, and tetrasporangia production, were evaluated from June to October 2010. The erect thalli appeared in autumn, and decayed in spring when they became overgrown by epiphytic diatoms. Vegetative thalli were usually smaller than fertile thalli. In spring, the thalli had the maximum mean values of length (199.5mm), thickness (52mm) and dried weight (4g). Although tetrasporophytes represented between 73% and 90% of the thalli collected each month, a few cystocarpic thalli were also found. Variations of thallus size and proportion of life history phases were also studied between 2010 and 2014. The inter-annual increase in the proportion of the tetrasporophytic phase and the progressive increase of the size of P. morrowii thalli indicated an ongoing establishment of the population in this habitat.

Seasonal population dynamics of Sargassum fusiforme (Fucales, Phaeophyta), Suo-Oshima Is., Seto Inland Sea, Japan\u2014development processes of a stand characterized by high density and productivity

Seasonal population dynamics of Sargassum fusiforme, one of the most important edible macroalgae in Japan, were studied. Recruits were mainly generated by vegetative reproduction at the margins of filamentous holdfasts. They first appeared in late spring and peaked in summer as upright thalli of the previous generation withered. After producing recruits, holdfasts withered indicating that holdfasts were also annual, the same as upright thalli. All recruits produced main branches and became new upright thalli in early autumn. During this transitional period, the thallus density decreased due to the crowded conditions induced by simultaneous growth initiation. After this early mortality, however, thallus density remained almost constant over much of the growth season. Thallus growth continued during winter and the stand biomass peaked in spring. During this biomass accumulation, development of a thallus size hierarchy was moderate and no size-dependent mortality was observed. Main branch number per thallus was also constant until spring, indicating the main branches also persisted after being produced in early autumn. This lack of severe intraspecific competition both at a thallus and main branch level is supported by the ambient wave condition of the habitat which gives moderate undulation and enables light and nutrients to be supplied to each thallus, and allowed the S. fusiforme stand to maintain its densely-packed feature with a high productivity.

Living inside a sponge skeleton: the association of a sponge, a macroalga and a diatom

The relationships between sponges and macroalgae have been poorly investigated, especially in temperate waters. This work describes the consortium between the dictyoceratid sponge Dysidea pallescens and the red alga Acrochaetium spongicola permeating spongin fibres in the Mediterranean Sea; moreover, this is the first report of a diatom, Amphora pediculus, living also inside the spongin skeleton. The annual trend of the total algal biomass did not vary over time in relation to the temperature, irradiance and incorporation of foreign bodies. Our analyses, conducted by light and electron microscopy, suggest that both the macroalga and the diatom invade the skeleton of the sponge from the external environment, and that the benthic diatom, epiphyte of the macroalga, is passively carried inside the fibres through the growth of Acrochaetium spongicola. All the examined samples of D. pallescens showed that the macroalga permeated at least some fibres, while the presence of the diatom was occasional. The superficial layer of the sponge, thin and reticulate, likely allows the passage of the light and ensures the algal survival inside the sponge tissue. The high occurrence of the association with A. spongicola, together with the morphological adaptations of the sponge favouring the algal life, suggest that the relationship is mutualistic. The possible benefits for the involved partners are hypothesized. The taxonomy and ecology of endozoic Acrochaetiales are controversial due to the reduced size of thalli, the absence of peculiar diagnostic characters and unknown reproductive structures. Therefore, detailed studies on the relationships between the algae and their hosts will provide helpful information for the algal identification.

Escape from the cryptic species trap: lichen evolution on both sides of a cyanobacterial acquisition event.

Large, architecturally complex lichen symbioses arose only a few times in evolution, increasing thallus size by orders of magnitude over those from which they evolved. The innovations that enabled symbiotic assemblages to acquire and maintain large sizes are unknown. We mapped morphometric data against an eight‐locus fungal phylogeny across one of the best‐sampled thallus size transition events, the origins of the Placopsis lichen symbiosis, and used a phylogenetic comparative framework to explore the role of nitrogen‐fixing cyanobacteria in size differences. Thallus thickness increased by >150% and fruiting body core volume increased ninefold on average after acquisition of cyanobacteria. Volume of cyanobacteria‐containing structures (cephalodia), once acquired, correlates with thallus thickness in both phylogenetic generalized least squares and phylogenetic generalized linear mixed‐effects analyses. Our results suggest that the availability of nitrogen is an important factor in the formation of large thalli. Cyanobacterial symbiosis appears to have enabled lichens to overcome size constraints in oligotrophic environments such as acidic, rain‐washed rock surfaces. In the case of the Placopsis fungal symbiont, this has led to an adaptive radiation of more than 60 recognized species from related crustose members of the genus Trapelia. Our data suggest that precyanobacterial symbiotic lineages were constrained to forming a narrow range of phenotypes, so‐called cryptic species, leading systematists until now to recognize only six of the 13 species clusters we identified in Trapelia.

Seasonal Variation in the Biomass, Size and Reproduction of the AgarophyteGracilariopsis sp.(Gracilareaceae, Rhodophyta) from a Temperate Lagoon in the Pacific Coast of Baja California Peninsula, México

Abstract Spatial and temporal changes in the population structure and standing crop of Gracilariopsis sp. were studied in the San Ignacio Lagoon during two different sampling periods. Biomass (wet weight, g m-2), thallus size and reproductive state were determined from November 2004 to August 2005. Standing crop was calculated from November 2007 to September 2008. The annual standing crop of Gracilariopsis sp. was estimated to be 1,300 wet tons. We found a seasonal growth cycle during both sampling periods, with the maximum biomass in spring (1,004 wet tons). Biomass was significantly higher near the mouth of the lagoon in shallow and sandy areas. This zone is associated with stronger currents and lower temperatures (annual mean of 20°C). The smallest thalli were found during autumn and winter, and the largest in spring. Senescence and detachment of the plants occurred in summer. Tetrasporangial thalli were the dominant phase in the population throughout the year, followed by vegetative (i.e. showing no r...

Preliminary Lichenometric Studies in Eastern and North-Western Himalaya

Abstract: Lichenometry is an extremely useful technique in dating moraine ridge and recent glacier retreat in polar and alpine regions. The study relates the size of the lichen thallus to the minimum age of the exposure of the surface on which it grows which consequently helps in assessment of the age of the boulders. The Lichenometric studies are carried out in Kupup and Thangu area of eastern Himalaya in Sikkim and Thajiwas glacier in Ganderbal district of north western Himalaya of Jammu and Kashmir with the help of diameters of a common crustose lichen Rhizocarpon geographicum growing luxuriantly on exposed boulder. The Thajiwas glacier showed retreat of 200 m in 279 years while in Thangu and Kupup area of eastern Himalaya the retreat was estimated as 200 m in 100 and 91 years respectively. The rate of retreat was slightly more faster in eastern Himalayan (20 mm/century) than the north-western Himalaya region (18.5mm/century).

First record of the noncalcareous macroalga Perissothallus from shallow-water deposits (Pennsylvanian) in the Kladno-Rakovník Basin, Czech Republic

The fossil genus Perissothallus is used for adpression fossils of late Palaeozoic noncalcareous freshwater algae consisting of erect, cylindrical branches that radiate from a central holdfast and dichotomize repeatedly. The taxon currently includes P. versiformis from the Upper Pennsylvanian of North America and P. densus from the Lower Permian of Germany. In this paper we describe a third species, Perissothallus dekovensis nov. sp., from the Gzhelian (Stephanian B;Upper Pennsylvanian) of the Kladno-Rakovnik Basin, Czech Republic. The new species differs from the previously described forms with regard to thallus size and branching pattern of the erect parts. Sedimentological data and the fossils that co-occur with the algal thalli suggest that P. dekovensis lived in shallow-water areas of a lake or abandoned channel that was surrounded by tree ferns, cordaites (especially Poacordaites-type), and lycopsids.

Thallus morphology of two Antarctic foliose lichens evaluated by a digital optical microscopy approach ( Short Communication)

Digital microscopy is an emerging technique that combines the tools of classic light microscopy with a computerized imaging system. The main components of digital microscopy is image formation by optics of the system, image registration by a digital camera, saving of image data in a file format that enables advanced image analysis.In this paper, we bring first data on application of digital microscopy approach in lichen thallus morphology study. Two Antarctic lichen species (Xanthoria elegans, Umbilicaria decussata) with a foliose morphotype of their thallus were studied. Both experimental species had an irregularly round or eliptic shape of a thallus that enabled to measure its diameter. After magnifition, images were taken in dry and fully-hydrated state of thallus in order to evaluate hydration-dependent size changes in thallus size and structures. It has been demonstrated that hydration-dependent size increment depend on thallus size and particular part of thallus. Mean increment of thallus diameter reached 15.1% and 13.8% for X. elegans and U. decussata, respectively. Higher value of diameter increment (26 %) was found for the upper projection area of apothecia, fruiting bodies developed over the upper thallus surface of X. elegans. Size and volume increment in thallus parts is discussed as a consequence of water holding capacity of lichens, and a capability of lichens to hold intra- and extracellular water upon full hydration of a thallus. Finally, a potential of digital microscopy for future studies is discussed as well as some processing techniques such as e.g. metrics of profile lines through 3-D objects like apothecia.

Tree species and microhabitat influence the population structure of the epiphytic lichen Lobaria pulmonaria

Detailed knowledge of the habitat requirements of species is required because habitat greatly affects the persistence of species. We investigated the effects of tree species and microhabitat heterogeneity on the population of the locally threatened lichen Lobaria pulmonaria. We studied four L. pulmonaria populations in Central Spain and collected microhabitat data for individuals growing on beech and oak. The microhabitat affected the life stages of L. pulmonaria; being a phorophyte species the location of the lichen was the most important factor generating different patterns of establishment, abundance, thallus size and reproductive capacity. Although oak forests favoured the establishment and recruitment of new L. pulmonaria individuals, they apparently provided adverse environmental conditions for lichen growth, thus affecting the reproductive capacity since this is size-dependent. By contrast, beech forests offered a more favourable microclimate, because L. pulmonaria individuals reached larger sizes in these forests. In conclusion, our results indicate that habitats hosting large populations, with high rates of establishment and recruitment do not necessarily favour other life-cycle stages.

Modeling of smart mixing regimes to improve marine biorefinery productivity and energy efficiency

Biorefineries aim to provide sustainable production of food and generation of low carbon energy in the next decades. Current strategies for biorefinery reply mostly on the classic terrestrial agriculture for biomass production. However, land availability, competition with food crops and total energy balance are challenging limiting factors for terrestrial bioenergy crop production. Off-shore macroalgae production could provide alternative, sustainable feedstocks for biorefineries without competition with food crops. Increasing the yields of off-shore macroalgae cultivation systems could further improve the total energy balance of the marine biorefineries. In this work, based on the fundamental principle of timing differences between light harvesting and carbon fixation in algae, we developed a theoretical framework for increasing the yields of off-shore macroalgae biomass using external mechanical mixing. We show that for a given physiological parameter of macroalgae light harvesting and carbon fixation, mixing could allow for increase of the total energy gain by two orders of magnitude. The overall biorefinery to biofuel efficiency, however, is constrained by drag and macroalgae thallus size.

The threatened epiphytic lichen Lobaria pulmonaria in the Iberian Peninsula: Genetic diversity and structure across a latitudinal gradient

The current genetic diversity and structure of a species plays a marked role in the species' future response to environmental changes. Identification of the factors that might ensure the long-term viability of populations along its distribution area is therefore important for conserving biodiversity. In this work, infraspecific genetic diversity and structure of the threatened lichen Lobaria pulmonaria was investigated along a latitudinal gradient, spanning the Spanish latitudinal range of L. pulmonaria. Eighteen populations in Northern, Central, and Southern Spain were analysed using six specific fungal microsatellites of L. pulmonaria. Genetic diversity indices were calculated and compared among populations. Genetic differentiation was assessed using AMOVA and Bayesian methods. Additionally, a redundancy analysis was used to estimate the relative importance of environmental factors on the genetic variation among populations. Annual precipitation was the only factor affecting the genetic diversity probably through its influence on population and thallus size of L. pulmonaria, and significantly higher levels of genetic diversity were detected in southern populations. Isolation by distance was not significant, being environmental variables most important factors controlling genetic variation in L. pulmonaria populations.

Relative growth rates and secondary compounds in epiphytic lichens along canopy height gradients in forest gaps and meadows in inland British Columbia

We explore relative growth rates (RGRs) and carbon-based secondary compounds (CBSCs) in epiphytic lichens along height-above-the-ground gradients. The chlorolichen (Letharia vulpina (L.) Hue), the cephalolichen (Lobaria pulmonaria (L.) Hoffm.), and the cyanolichens (Lobaria hallii (Tuck.) Zahlbr., Nephroma helveticum Ach.) were attached to branches at 0.5–3.0 m heights of young spruce trees transplanted for 1 year in forest gaps and in old meadows of an inland valley in British Columbia. Cephalolichen and cyanolichen RGRs were highest in forest gaps, whereas the chlorolichen grew faster in meadows with twice as much light as forest gaps. Transplantation height did not influence lichen temperature or RGRs, despite height-dependent light increases. CBSCs were highest in the chlorolichen (13%), followed by the cephalolichen (5%) and the cyanolichens (1% and 0%). CBSC concentrations increased with thallus size, and were significantly higher in forest gaps mainly for L. pulmonaria. Only one minor CBSC in each species varied with height. The slow growth of cephalolichen and cyanolichens in meadows is consistent with these lichens’ preferences for forested habitats. Cold air ponding from snow-capped mountains was probably strong enough to form enough nocturnal dew to support reasonable lichen growth at all heights. The high species-specific and the low habitat-specific CBSC variations are consistent with constitutive CBSC defense levels in studied lichens.

БІОЕКОЛОГІЧНИЙ АНАЛІЗ ЕПІФІТНИХ ЛИШАЙНИКІВ PHYSCIA В УМОВАХ ГІРНИЧО-МЕТАЛУРГІЙНОГО КОМПЛЕКСУ КРИВБАСУ

<p>The comparative analysis of lichens <em>Physcia</em>. Рopulation at different levels of aerotechnogenic pollution of industrial mining – metallurgical complex of Krivyi Rig Basin. In the highway area there was found the worsening living conditions of thallus at the lichens <em>Physcia</em><em>, </em>manifested in the reduction of a projective cover and reducing of the size of thallus with the increasing of the degree of their damage.<strong> </strong>It is set that specific composition and conformities to law of distribution of cladinas is determined the type of the industrial loading. Predominance at the lichens of crustaceous cladinas, insignificant participation of fissile cladinas and complete absence of bushy forms is the possible consequence of industrial influence.</p> <p>We registered some 3 species of epiphytic lichens, namely Phaeophyscia nigricans, Physcia tenella, Physcia adscendens in a residential zone, while on conditional control area we found Physcia orbicularis. The dominant species was scum-like shape Phaeophyscia nigricans, Physcia adscendens, Physcia tenella, while on conditional control region we marked predominance of Physcia orbicularis and did not registered bushy lichens form.</p> <p>We also divided the lichens into two groups according to the resistance towards air pollution - moderate (2 species, Phaeophyscia nigricans, Physcia tenella) and toxic-resistant (2 species, Physcia orbicularis, Physcia adscendens). Epiphytic lichens in terms of residential areas compared to conventionally control area characterized by a decrease of morphometric parameters of the melt. Key results can be used to predict the state of ecosystems using lichenoindication in terms of industrial regions of Ukraine.</p> <p><em>Keywords</em><em>:<strong> </strong></em><em>lichen, projective cover, </em><em>floristic composition, </em><em>lichenoindication</em><em>.</em><em></em></p>

Does thalli complexity and biomass affect the associated flora and fauna of two co-occurring Fucus species in the Baltic Sea?

On rocky shores, fucoids provide habitat, shelter and food for associated biota. In the northern parts of the Baltic, the Bothnian Sea, the new fucoid species Fucus radicans (Bergström et Kautsky) was recently described. This study compares the thallus complexity and size as well as quantified the abundance and biomass of epiphytic algae and invertebrate taxa of the two fucoid species F. radicans and Fucus vesiculosus L. from sympatric sites in the Bothnian Sea on the Swedish coast and around the Estonian island Saaremaa. We found that F. radicans was more complex than F. vesiculosus within the whole study range, but both species had a more complex thallus structure in the Bothnian Sea compared to Estonia. The complexity of host algae did not contribute to their associated flora and fauna taxon richness; instead, the size of thalli was a good proxy for associated communities. Specifically, on a biomass basis, F. vesiculosus displayed highest species richness and highest faunal abundance in the Bothnian Sea, whereas no such differences were found around Saaremaa, probably because both Fucus species had similar height around Saaremaa whereas F. vesiculosus grew much taller and larger in the Bothnian Sea. There were some unique associated macroalgal and invertebrate species that were found only on either of the fucoids, indicating the importance of separating them as species in surveys and monitoring.

Using earthquakes to assess lichen growth rates

Botanists make yearly measurements of lichen sizes that describe highly variable radial expansion of young, and old, hizocarpon subgenus hizocarpon that is a function of thallus size and age. Such non‐uniform growth would negate use of lichens to date geomorphic events, such as landslides and moraines, of the past 1000 years. Fortunately, many crustose lichens tend toward circular shapes, which can be achieved only when overall uniform radial growth prevails.Largest lichen measurements on rockfall blocks that accumulate incrementally as hillslope talus in earthquake‐prone alifornia plot as distinct peaks in frequency distributions. Rockfall surface‐exposure times are known to the day for historical earthquakes and to the year where mass movements damage trees. Lichenometry consistently dates regionally synchronous rockfall events with an accuracy and precision of ±5 years. Only historical records and tree‐ring dating of earthquakes are better.The four crustose lichens used here have constant long‐term growth rates, ranging from 9.5 to 23.1 mm per century. Growth rates do not vary with altitude or climate in a 900 km long mountainous study region in alifornia, . Linear growth regressions, when projected to the present, constrain estimates of colonization time and possible styles of initial lichen growth.

What factors influence the occurrence of the genus Degelia (a threatened lichen) in central Spain?

The main factors determining the occurrence, abundance, growth and reproductive capacity of threatened lichens need to be known in order to implement conservation initiatives. The main objective of the present study was to evaluate which factors affect the conservation status of Degelia species-complex in central Spain. We undertook a non-parametric analysis to evaluate whether population sizes are larger in protected areas. We fitted generalized linear models (GLM) and mixed models (GLMMs) to analyze which variables are driving occurrence and abundance of Degelia , the thallus size and reproduction capacity. Results show that population sizes of Degelia are very variable, being larger in broad-leaved evergreen forests and inside protected areas. Tree characteristics play an important role in its local dynamics. • Degelia genus is very scarce in Mediterranean Spain. • Population size is highly variable in the study area. • Larger populations are found in evergreen forests and inside protected areas. • Tree characteristics influence local dynamics of Degelia populations.

Seasonal changes in population structure of the tropical deep‐water kelp Laminaria abyssalis

SummaryTropical kelp populations are rare and anomalous relicts of shallow‐water populations that existed during glacial periods of cooler oceanographic climate. The endemic Brazilian tropical kelp, Laminaria abyssalis Joly and Oliveira Filho, occurred at depths below 40 m. The seasonal variations in biological aspects of L. abyssalis sporophyte populations and local variations in seawater nutrients and temperature were evaluated. A population was sampled four times between the austral spring of 2005 to winter 2006. Seasonal variations in the population structure and in the tissue content of nitrogen (N), carbohydrate and pigments were observed. Higher density (6.3 individuals m−2), biomass (7.3 kg m−2) and blade area (13 221 cm2) were observed in summer, while the highest percentage of tissue total N (1.6%), carbohydrates (32.9%) and photosynthetic pigments (chlorophyll a = 1.9% and chlorophyll c = 0.4%) were observed in spring. The highest surface area of fertile tissue in L. abyssalis sporophytes (2.36%) was recorded in winter, indicating winter as the season when more investments are made in reproduction. The highest concentrations of total N (6.3 μM) and phosphate (0.6 μM) in seawater were observed in spring and summer, respectively. Seawater temperatures lower than 20°C, which are characteristic of upwelling waters, occurred every month and were most frequent in spring and summer. We show that L. abyssalis invests more in growth in spring and summer and reaches the greatest thallus size and population density in summer. The lower abundance during winter may be related to the lower frequency of temperatures below 20°C and the local seasonal storms that cause turnover of rhodoliths, the main substrate for L. abyssalis.

Taxonomic reassessment of Chondrus verrucosus (Rhodophyta, Gigartinales), with a description of Chondrus retortus sp. nov

SummaryPhylogenetic and morphological reinvestigation of Chondrus verrucosus Mikami was conducted in the Pacific coast of southeastern Honshu, Japan, including the holotype specimen and samples near the type locality. Two entities were recognized by phylogenetic analyses of plastid rbcL and nuclear EF2 sequences. In morphological analyses, the two entities were distinguished by: (i) thallus size and form, and (ii) cell shape of the medullary layer surrounding young carposporangia: one has larger thalli, is regularly canaliculated, with linear medullary cells (large‐type); the other is smaller, canaliculated with crispation and has roundish medullary cells (small‐type). The large‐type was common in southern to eastern Boso Peninsula including near the type locality; the small‐type was typical in the southwest Boso Peninsula and Sagami Bay. The large‐type was shown to be equivalent to C. verrucosus by examination of the holotype specimen. The small‐type is described as a new species, C. retortus Matsumoto et Shimada.

A comparison ofLobaria pulmonariapopulation structure between subalpine fir (Abies lasiocarpa) and mountain alder (Alnus incana) host-tree species in British Columbia’s inland temperate rainforest

In a study using dated branch segments, we determined the size class distribution and reproductive status of Lobaria pulmonaria (L.) Hoffm. growing on subalpine fir (Abies lasiocarpa Nutt.) and mountain alder (Alnus incana (L.) Moench) alongside small streams in British Columbia’s inland temperate rainforest (ITR). The number of thalli per branch segment did not significantly differ between Abies and Alnus, although mean L. pulmonaria biomass on entire branches was 71.03 g on fir and 12.31 g on alder. Branch diameter was a significant predictor for reproductive status of thalli on fir, whereas branch age was a better predictor for thalli on mountain alder. The presence of sorediate and (or) isidiate individuals on branch segments <10 years old suggests a rapid generation time for L. pulmonaria in the ITR. Annual growth rates of L. pulmonaria thalli reached up to 1.16 cm2·cm−2·yr−1on branch segments less than 15 years in age. Specific thallus mass (STM) was significantly higher for thalli on alder. STM was strongly dependent on thallus size on both host-tree species, with values from above 10 mg.cm−2in large thalli (>100 cm2), to <3 mg.cm−2in small thalli (<0.1 cm2). These differences between host-tree species can be interpreted in context of both adjacent canopy structure and the differences in tree growth form between these two host-tree species, both of which factors lead to greater light availability at the surface of mountain alder branches. The fast growth rates and short generation time observed in L. pulmonaria thalli growing on both alder and fir highlights the favorable conditions riparian habitats create for lichen growth in British Columbia’s ITR.