Influence of mesoscale physical forcing on trophic pathways and fish larvae retention in the central Cantabrian Sea

This study was carried out over the central Cantabrian shelf during a post‐bloom phase in May. Late phases of the spring phytoplankton bloom, which are characterized by high crustacean mesozooplankton biomass, have been proposed to be a particular case for high‐energy flow towards large metazoans. The overall objective of the study is to analyse the influence of mesoscale physical forcing on primary production patterns, its implications on food web pathways, and on larval fish distribution during a period of intense spawning of Sardina pilchardus and Scomber scombrus. Physical and biological variables of different trophic levels show coupled cross‐shelf and along‐shelf heterogeneity. Quasi‐geostrophic analysis and other indirect approaches, such as the depth of the slope salinity maximum, reveal predictable patterns of vertical instabilities associated with mesoscale physical forcing that enhance production of large‐size phytoplankton. The latter is expected to enhance the energy flow towards higher trophic levels at a time of high mesozooplankton biomass. Distributions of S. pilchardus and S. scombrus eggs and larvae indicate retention related to the coastal salinity front and the overall eastward circulation pattern. The observed mesoscale physical processes may favour survival of early stages of fish by their influence on the energy flow of primary production towards higher trophic levels and larval retention at the coast.     

Growth, survival, quality and digestive enzyme activities of larval shrimp fed microencapsulated, mixed and live diets

An artificial diet for shrimp larvae was microencapsulated with a polysaccharide blend [66% gum arabic, 17% mesquite gum and 17% maltodextrin 10 dextrose equivalent (DE)]. Microencapsulated diet (MD) was fed to mysis alone, as a co‐feed with the microalgae Chaetoceros cerastosporum and Tetraselmis chuii (mixed) and compared with a live diet (control) of C. cerastosporum, T. chuii and Artemia nauplii. No significant differences (P > 0.05) were detected in growth rates, development and quality indexes of larvae fed the three experimental diets. All diets supported survival percentages of >90%. Shrimp larvae fed MD and mixed diets had higher specific trypsin activity and soluble protein content than those fed live diet. Amylase activity decreased in larvae fed the mixed and MD apparently due to the carbohydrate composition of the diet. The results indicate that it is possible to substitute a live diet with a microencapsulated one (with a wall composition made up of a polysaccharide blend) in Litopenaeus vannamei mysis.     

New hosts for Lecanosticta acicola and Dothistroma septosporum in newly established arboreta in Spain

A historical outbreak of needle blight disease was recorded during 2018 to 2019 in plantations of Pinus radiata and Pinus nigra in the North of Spain. The main pathogens involved in this historical outbreak were identified as Lecanosticta acicola and Dothistroma septosporum. Recently, a variety of tree species in three arboreta planted between 2011 and 2013 in the Basque Country as part of the European project REINFFORCE were showing symptoms of needle blight and defoliation. The aim of this study was to determine which pine species were affected with these pathogens. Tree species sampled included several provenances of P. brutia, P. elliottii, P. nigra, P. pinaster, P. pinea, P. ponderosa, P. sylvestris and P. taeda. Using molecular identification methods, Lecanosticta acicola was confirmed infecting Pinus brutia (Provenance: Alexandropolis, Greece and var. eldarica, Crimea) and represents a new host species for this pathogen. Pinus elliottii (Provenance: Georgia, USA) and P. ponderosa (Provenance: Central California, USA) are new host reports of L. acicola for Spain. Dothistroma septosporum was found for the first time on P. brutia (Provenance: Marmaris, Turkey) and P. ponderosa (Provenance: Oregon, USA) in Spain and was also detected infecting P. nigra (Provenance: Sologne Vayrières, France).     

Cholera dynamics and El Niño-Southern Oscillation

Analysis of a monthly 18-year cholera time series from Bangladesh shows that the temporal variability of cholera exhibits an interannual component at the dominant frequency of El Ni?o-Southern Oscillation (ENSO). Results from nonlinear time series analysis support a role for both ENSO and previous disease levels in the dynamics of cholera. Cholera patterns are linked to the previously described changes in the atmospheric circulation of south Asia and, consistent with these changes, to regional temperature anomalies.     

Ecological forecasts: an emerging imperative

Planning and decision-making can be improved by access to reliable forecasts of ecosystem state, ecosystem services, and natural capital. Availability of new data sets, together with progress in computation and statistics, will increase our ability to forecast ecosystem change. An agenda that would lead toward a capacity to produce, evaluate, and communicate forecasts of critical ecosystem services requires a process that engages scientists and decision-makers. Interdisciplinary linkages are necessary because of the climate and societal controls on ecosystems, the feedbacks involving social change, and the decision-making relevance of forecasts.     

Competition of superconducting phenomena and Kondo screening at the nanoscale

Magnetic and superconducting interactions couple electrons together to form complex states of matter. We show that, at the atomic scale, both types of interactions can coexist and compete to influence the ground state of a localized magnetic moment. Local spectroscopy at 4.5 kelvin shows that the spin-1 system formed by manganese-phthalocyanine (MnPc) adsorbed on Pb(111) can lie in two different magnetic ground states. These are determined by the balance between Kondo screening and superconducting pair-breaking interactions. Both ground states alternate at nanometer length scales to form a Moiré-like superstructure. The quantum phase transition connecting the two (singlet and doublet) ground states is thus tuned by small changes in the molecule-lead interaction.     

South american geochronology: radiometric time scale for middle to late tertiary mammal-bearing horizons in patagonia

Radiometric (potassium-argon) age determinations for basalts and tuffs associated with middle to late Tertiary mammal-bearing horizons in Patagonia, southern Argentina, permit refinement of boundaries and hiatuses between beds of Deseadan (early Oligocene) through Friasian (middle to late Miocene) age. At two localities beds of Deseadan age are overlain by basalts, which gave dates of 33.6 and 35.4 million years ago; 34.0 million years ago is tentatively accepted as a terminal date for known Deseadan. At several localities beds of Colhuehuapian age are underlain by basalts, which gave dates ranging from 28.8 to 24.3 million years ago; 25.0 million years is tentatively taken as a basal age for known Colhuehuapian. The paleontological hiatus between known Deseadan and known Colhuehuapian is thus in the order of 9.0 million years. Two tuffs from the Santa Cruz Formation (Santacrucian) gave ages of 21.7 and 18.5 million years. Plagioclase and biotite concentrates of an ignimbrite from the Collón Curá Formation (Friasian) gave ages ranging from 15.4 to 14.0 million years.     

Effect of Water Temperature on Reproductive Tract Condition of Penaeus setiferus Adult Males

Abstract— This study was conducted to determine the effect of water temperature on male reproductive tract degenerative syndrome (MRTDS) and male reproductive system melanization (MRSM) in Penaeus setiferus , and to evaluate the effect of water temperature on spermatophore regeneration time and sperm quality in electrically ejaculated adult males. Variation in sperm quality, gonadosomatic index, and histological changes in the reproductive system were used to assess reproductive tract changes in the first experiment. Sperm quality and regeneration time were measured before and after successive regenerations in the second experiment. Sperm quality was stable when shrimp were held at 26 C for 30 d but was reduced when shrimp were held at 30 C. Reproductive tissues of 20% of the shrimp held at 30 C were melanized to some degree but tissue melanization was found in only 2.5% of the shrimp held at 26 C. Spennatophore regeneration time was also affected by temperature. Average times for first spermatophore regeneration were 192 h at 25 C, 152 h at 30 C, and 144 h at 33 C. Sperm quality of regenerated shrimp was not affected at 25 C but was reduced for regenerated animals held at 33 C. Based on these results, we recommend a water temperature between 25 and 27 C to obtain adequate spermatophore regeneration and to maintain healthy male P. setiferus broodstock for at least 30 d.     

Tissue Lipid Content and Fatty Acid Composition of Penaeus monodon Fabricius Broodstock from the Wild

Tissues (hepatopancreas, muscle, gonad) of wild Penacus mordon females with ovaries in different stages of development and males were analyzed for Upid content and fatty acid composition. Hepatopancreatic tissue had the highest mean levels of lipid at 15.72–25.20% in females and averaged 46.20 ± 1.53% in males. Levels of Lipid in the muscle were low with no marked variation throughout the maturation s-es. Ovarian lipid levels increased significantly at stage II (early maturing ovaries) and remained high through stage IV (fully mature ovaries). Peak lipid level was found at stage III (late maturing ovaries) and coincided with a decline in hepatopancreas lipid. Ovarian and hepatopancreatic lipids declined drastically in spent females. Profiles of fatty acid in the tissues consistently showed the presence of PUFA 204n-6, 20:5n-3 and 22611-3, with high levels in the polar lipid fraction of vitellogenic ovaries. These values were reflected in the male testis and spawned eggs. The finding suggest storage and utilization of lipids for maturation and spawning processes and that the phospholipids were mainly responsible for increases in ovarian lipids. The type of fatty acids present in maturing prawn ovaries is indicative of their importance in reproductive physiology.