Publications

MESSAGE FROM THE PRESIDENT: IS ASLO INTERNATIONAL ENOUGH?

POPULATION STRUCTURE, DYNAMICS, AND PRODUCTION OF THE MEDITERRANEAN MACROALGA <i>CODIUM BURSA</i> (CHLOROPHYCEAE)

The biochemical composition and metabolism of the balloonlike Mediterranean macroalga Codium bursa J. Agardh are strongly size dependent and constrained by the spherical geometry of its thallus. Changes in reproductive phenology, population structure, density, biomass, and production of this widespread alga were followed over an annual cycle to examine whether mortality rate was size and age dependent. Examination of size and age distributions showed the population to be in quasi‐steady state. A main recruitment event occurred in winter, with the highest gametangial densities observed in October, and the peak of recruits observed in December. The small recruits (0–2 cm in diameter) exhibited high growth (1 cm in &lt;1 month) and mortality rates. High exponential mortality rate was also observed in the larger individuals (&gt;12 cm, or 6 years old). Intermediate size C. bursa showed the lowest mortality rate, indicating that organisms within this size range (3–12 cm) escape advective and grazing losses that decimate small recruits and that they, unlike larger organisms, maintain an adequate physiological status. Asexual gemmation within the intermediate size classes may also contribute to maintain stable populations of this species in the NW Mediterranean littoral zone, since recruits derived from sexual reproduction experience extremely high mortality rates.

Laser‐Printed, Flexible Graphene Pressure Sensors (Global Challenges 4/2020)

In article number 2000001, Jurgen Kosel and co-workers design a wearable, flexible piezoresistive graphene sensor by a facile, one-step laser-printing fabrication process. The sensors feature long-term stability, biocompatibility, and a low detection limit in combination with an extensive dynamic range. They can function as wearable artificial skins, monitors for heart rate or plantar pressure, or provide a tactile sense. They can also be employed in harsh environments.

Rhizome elongation and seagrass clonal growth

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 174:269-280 (1998) - doi:10.3354/meps174269 Rhizome elongation and seagrass clonal growth Núria Marbà1,*, Carlos M. Duarte2 1Centre for Estuarine and Coastal Ecology, NIOO, Korringaweg 7, 4401 NT Yerseke, The Netherlands 2Centre d'Estudis Avançats de Blanes, CSIC, Camí de Sta. Bàrbara s/n, E-17300 Blanes, Spain *Present address: Centre d'Estudis Avançats de Blanes, CSIC, Camí de Sta. Bàrbara s/n, E-17300 Blanes, Spain. E-mail: marba@ceab.csic.es ABSTRACT: A compilation of published and original data on rhizome morphometry, horizontal and vertical elongation rates and branching patterns for 27 seagrass species developing in 192 seagrass stands allowed an examination of the variability of seagrass rhizome and clonal growth programmes across and within species. Seagrass horizontal rhizomes extend at rates ranging between 1.2 and 574 cm yr-1, develop a branch, with an angle from 19 to 72°, for every 6 to 1800 horizontal internodes, and add a new shoot for every 1.1 to 7.5 cm of rhizome produced. Vertical rhizomes elongate at rates between 0.1 and 34 cm yr-1 and the probability that they will branch varies over 3 orders of magnitude. Much (between 40 and 173%) of the variability of seagrass horizontal rhizome and clonal growth programmes is species-specific, largely (21 to 63% of the variance) associated with differences in size among species, although seagrasses also show important intraspecific variability. The broad repertoire of seagrass rhizome and clonal growth programmes explains the different rates and efficiency at which the species occupy space. The implications of specific growth programmes for space occupation were examined by simulating the development of seagrass rhizome networks of 3 seagrass species encompassing the range of horizontal rhizome growth (Halophila ovalis, Thalassodendron ciliatum, Posidonia oceanica). This exercice showed that small, fast-growing species achieve a much lower spread efficiency (m2 of ground covered m-1 of rhizome produced) than the large, slow-growing species. Differences in rhizome branching angles greatly constrained the form of rhizome networks. The results show that clonal growth patterns are a primary component of seagrass productivity and, therefore, the key to the development and maintenance of seagrass meadows. KEY WORDS: Seagrasses · Clonal growth · Plant allometry · Rhizome diameter · Spacer length · Rhizome elongation · Branching rate and angle Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 174. Publication date: November 26, 1998 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1998 Inter-Research.

DIC dynamics in the Bay of Palma (NW Mediterranean)

Introduction: Understanding Jellyfish Blooms

Areal Extent, Species Composition, and Spatial Distribution of Coastal Saltmarshes in China

Coastal saltmarshes are key ecosystems with important ecological functions. Yet, they have experienced a widespread decline. Due to their importance, the conservation and restoration of saltmarshes are globally shared objectives, including China. Despite multiple local studies, nationwide information about saltmarshes in China is scarce. Thus, we used remote sensing to delineate the spatial distribution and areal extent of saltmarshes along coastal China and resolve their species composition. By interpreting 10 m spatial resolution Sentinel-2 images on Google Earth Engine, assisted with field survey and literature search, a total of 118 010 ha of saltmarshes were delineated in coastal China in 2019. Seven typical saltmarsh species were identified, with <i>Phragmites australis</i>, <i>Spartina alterniflora,</i> and <i>Scirpus mariquater</i> as dominant species, accounting for 95.5&#x0025; of total saltmarsh extent, while <i>Suaeda salsa</i>, <i>Tamarix chinensis</i>, <i>Cyperus malaccensis,</i> and <i>Sesuvium portulacastrum</i> were present in limited abundance. The <i>P. australis</i> and exotic species <i>S. alterniflora</i> grow along almost all coastal provinces, but <i>P. australis</i> dominates in the north while <i>S. alterniflora</i> dominates in the middle part of coastal China. <i>Suaeda salsa</i> occurs mainly in the north and has suffered large losses. <i>Tamarix chinensis</i> is abundant in Shandong province, <i>S. mariquater</i> in the Yangtze River delta, <i>C. malaccensis</i> in Guangdong and Guangxi provinces, and <i>S. portulacastrum</i> in Taiwan. The exotic species <i>S. alterniflora</i> expanded extensively along the coast and its expansion rate continues to increase. The results provided conform a much-needed baseline for future monitoring efforts and the assessment of progress in the conservation and restoration projects toward recovering saltmarshes in China.

Claims That Anthropogenic Stressors Facilitate Jellyfish Blooms Have Been Amplified Beyond the Available Evidence: A Systematic Review

The perception that anthropogenic stressors cause jellyfish blooms is widespread within the scientific literature and media but robust evidence in support of these claims appears scarce. We used a citation analysis of papers published on "jellyfish blooms" to assess the extent to which such claims are made and the robustness of the evidence cited to support claims. Our search of the Web of Science returned 365 papers on "jellyfish blooms". Each paper was searched for statements linking jellyfish blooms to specific anthropogenic stressors. For each statement we recorded the affirmation afforded to the claim, identified the stressors purported to cause blooms, the sources cited to support the statement, the type of study cited and the species studied in the cited source. Almost half the papers claimed that blooms were facilitated by anthropogenic stressors but most (70%) afforded a low degree of affirmation to the claim. We identified three major limitations in the evidence used to support claims: 1) evidence was dominated by studies of two wide-spread and highly invasive taxa (Aurelia aurita and Mnemiopsis leidyi) that may not represent the responses of jellyfishes more generally; 2) the empirical studies cited were dominated by correlative studies which, whilst useful for generating hypotheses, cannot attribute causation; and 3) the most commonly-cited reviews often cited circumstantial evidence and other reviews and provided conceptual models of how stressors could influence blooms, rather than robust evidence. We conclude that, although anthropogenic stressors could enhance jellyfish blooms, robust evidence is limited. Claims that strongly affirm anthropogenic stressors as causes of jellyfish blooms appear to be amplifying the evidence beyond that available. As a community we need to strike a better balance between perpetuating perception and accurately portraying the state of knowledge. Moreover, we should consider that anthropogenic stressors may adversely affect some species of jellyfish.

Flexible and Multi-Functional Graphene Sensor Platform

This paper presents a flexible, printed and robust sensor platform for the detection of various parameters: strain, flow speed, pressure, conductivity, temperature and magnetic field. The sensors are based on Laser-Induced Graphene fabricated by laser printing on Kapton substrate. Multi-functionality is obtained by exploiting printing process combined with the flexible nature of Kapton and the piezoresistivity of Graphene. Sensor have been implemented for the detection of strain, flow speeds, forces pressure, salinity and magnetic field. Their sensitivity and dynamic range can be tailored via the substrate and laser printing design. A robust and reliable operation was obtained during underwater experiments in the Red Sea.

Dissolved organic carbon fluxes by seagrass meadows and macroalgal beds

Estimates of dissolved organic carbon (DOC) release by marine macrophyte communities (seagrass meadows and macroalgal beds) based on in situ benthic chambers from published and unpublished are compiled in this study. The effect of temperature and light availability on DOC release by macrophyte communities was examined. Almost 85 % of the seagrass communities and all of macroalgal communities examined acted as net sources of DOC. Net DOC fluxes in seagrass communities increase positively with water temperature. In macroalgal communities net DOC fluxes under light exceeded those under dark condition, however, this trend was weaker in seagrass communities. Shading of a mixed seagrass meadow in The Philippines led to a significant reduction on the net DOC release when shading was maintained for 6 days compared to only 2 days of shading. Net DOC fluxes increased with increasing community respiration, but were independent of primary production or net community production. The estimated global net DOC flux, and hence export, from marine macrophytes is about 0.158 ± 0.055 Pg C yr-1 or 0.175 ± 0.056 Pg C yr-1 depending on the global extent of seagrass meadows considered.

Rapid carbon cycling in the oligotrophic ocean

Abstract. The dynamics of organic carbon production, release and bacterial use was examined across a range of communities spanning from highly oligotrophic ones in the Subtropical Atlantic Ocean, mesotrophic ones in the Mediterranean Sea and productive ones in the Northern African upwelling and the Southern Ocean. A comparative analysis of experiments examining total and particulate organic carbon production across a range of time scales (15 min to 24 h) for 20 communities with contrasting phytoplankton cell status, as assessed by cell lysis rates, and the use of a simple inverse model was used to resolve patterns of carbon flow in the microbial food web. Communities in productive ocean waters accumulated organic carbon over hourly time scales, whereas only a small fraction of net primary production accumulated in communities from oligotrophic waters. These communities supported high phytoplankton cell lysis rates leading to a rapid flux of organic carbon to bacteria, which had high affinity for phytoplankton-derived carbon, much of which was rapidly respired. Conventional assessments of primary production in the oligotrophic ocean severely underestimate net phytoplankton production, as carbon flow in microbial communities from oligotrophic ocean waters occurs within short (minutes) time scales. This explains difficulties to reconcile estimates of primary production with independent estimates of carbon use by bacteria in oligotrophic marine ecosystems.

O quadro recente de emprego dos mestres e doutores titulados no Brasil

Loss-controlled phytoplankton production in nutrient-poor littoral waters of the NW Mediterranean:in situ experimental evidence

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 130:213-219 (1996) - doi:10.3354/meps130213 Loss-controlled phytoplankton production in nutrient-poor littoral waters of the NW Mediterranean: in situ experimental evidence Mura MP, Agustí S, del Giorgio PA, Gasol JM, Vaqué D, Duarte CM The role of losses in controlling phytoplankton biomass and production off Blanes Bay (NW Mediterranean) were examined, using insitu dialysis cultures, during a period of very low nutrient concentration. The ambient community experienced a negative net growth rate (-0.05 +/- 0.03 divisions d-1), compared to relatively high community growth rates (0.78 +/- 0.07 div. d-1) when metazoan grazers and physical losses, which appeared to be negligible, were excluded, indicating that loss rates (0.83 div. d-1) exceeded growth rates. This provided evidence that the biomass and production of the phytoplankton community was controlled by consumers, even at a time of very low nutrient concentrations. The community structure changed in response to the suppression of losses, leading to an enhanced growth of nano- and microphytoplankton, while the abundance of picoplanktonic autotrophs tended to decline slightly. Yet, the biomass attained by nano- and microphytoplankton was similar despite large differences in their initial density, indicating the existence of a resource limitation of the biomass the different groups may achieve. These results clearly provide evidence that the biomass and production of larger (&GT5 um) phytoplankton was controlled top-down by metazoan consumers, which were excluded from the dialysis bags, while picophytoplankton biomass was likely to be controlled by protists. This supports the notion that whether autotrophic production is channelled through metazoan herbivores or through the 'microbial loop' is closely dependent on the size (greater and smaller than about 5 um, respectively) of the autotrophs, and that top-down control of phytoplankton production may occur even when nutrients are very scarce. Phytoplankton . NW Mediterranean . Growth . Losses Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 130. Publication date: January 11, 1996 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1996 Inter-Research.

To produce many small or few large eggs: a size-independent reproductive tactic of fish

Vicariance patterns in the Mediterranean Sea: east–west cleavage and low dispersal in the endemic seagrass <i>Posidonia oceanica</i>

Abstract Aim The seagrass, Posidonia oceanica is a clonal angiosperm endemic to the Mediterranean Sea. Previous studies have suggested that clonal growth is far greater than sexual recruitment and thus leads to low clonal diversity within meadows. However, recently developed microsatellite markers indicate that there are many different genotypes, and therefore many distinct clones present. The low resolution of markers used in the past limited our ability to estimate clonality and assess the individual level. New high‐resolution dinucleotide microsatellites now allow genetically distinct individuals to be identified, enabling more reliable estimation of population genetic parameters across the Mediterranean Basin. We investigated the biogeography and dispersal of P. oceanica at various spatial scales in order to assess the influence of different evolutionary factors shaping the distribution of genetic diversity in this species. Location The Mediterranean. Methods We used seven hypervariable microsatellite markers, in addition to the five previously existing markers, to describe the spatial distribution of genetic variability in 34 meadows spread throughout the Mediterranean, on the basis of an average of 35.6 (± 6.3) ramets sampled. Results At the scale of the Mediterranean Sea as a whole, a strong east–west cleavage was detected ( amova) . These results are in line with those obtained using previous markers. The new results showed the presence of a putative secondary contact zone at the Siculo‐Tunisian Strait, which exhibited high allelic richness and shared alleles absent from the eastern and western basins. F statistics (pairwise θ ranges between 0.09 and 0.71) revealed high genetic structure between meadows, both at a small scale (about 2 to 200 km) and at a medium scale within the eastern and western basins, independent of geographical distance. At the intrameadow scale, significant spatial autocorrelation in six out of 15 locations revealed that dispersal can be restricted to the scale of a few metres. Main conclusions A stochastic pattern of effective migration due to low population size, turnover and seed survival is the most likely explanation for this pattern of highly restricted gene flow, despite the importance of an a priori seed dispersal potential. The east–west cleavage probably represents the outline of vicariance caused by the last Pleistocene ice age and maintained to this day by low gene flow. These results emphasize the diversity of evolutionary processes shaping the genetic structure at different spatial scales.

Phytoplankton chlorophyll a distribution and water column stability in the central Atlantic Ocean

Seasonality of marine plastic abundance in central Red Sea pelagic waters

Publisher Correction: KAUST Metagenomic Analysis Platform (KMAP), enabling access to massive analytics of re-annotated metagenomic data