Transgenerational effects alleviate severe fecundity loss during ocean acidification in a ubiquitous planktonic copepod

Ocean acidification (OA) caused by anthropogenic CO2 emission is projected for thousands of years to come, and significant effects are predicted for many marine organisms. While significant evolutionary responses are expected during such persistent environmental change, most studies consider only short-term effects. Little is known about the transgenerational effects of parental environments or natural selection on the capacity of populations to counter detrimental OA effects. In this study, six laboratory populations of the calanoid copepod Pseudocalanus acuspes were established at three different CO2 partial pressures (pCO2 of 400, 900 and 1550 μatm) and grown for two generations at these conditions. Our results show evidence of alleviation of OA effects as a result of transgenerational effects in P. acuspes. Second generation adults showed a 29% decrease in fecundity at 900 μatm CO2 compared to 400 μatm CO2. This was accompanied by a 10% increase in metabolic rate indicative of metabolic stress. Reciprocal transplant tests demonstrated that this effect was reversible and the expression of phenotypic plasticity. Furthermore, these tests showed that at a pCO2 exceeding the natural range experienced by P. acuspes (1550 μatm), fecundity would have decreased by as much as 67% compared to at 400 μatm CO2 as a result of this plasticity. However, transgenerational effects partly reduced OA effects so that the loss of fecundity remained at a level comparable to that at 900 μatm CO2. This also relieved the copepods from metabolic stress, and respiration rates were lower than at 900 μatm CO2. These results highlight the importance of tests for transgenerational effects to avoid overestimation of the effects of OA

Green Building: Sustainable Water Consultancy

The aim of this report is to present the results of water and wastewater modelling undertaken as part of a sustainable water consultancy for the ACF/Surrowee Green Building Project. The Institute for Sustainable Futures was engaged to develop a series of options, and to undertake modelling of the hydraulic, technical, economic and other aspects of these options and their implementation, in cooperation with the Design Team and other stakeholders. For a building of this type to achieve the goal of worldâs best practice environmental performance in a commercially viable office building, it is imperative that scheme water demand be reduced as much as possible. The practical limits of demand reduction were tested by detailed end-use modelling of various sustainable water management âoptionsâ incorporating water efficiency, reuse and dry sanitation technologies. The results of modelling and the cost benefit analysis indicate that many of the options would provide net financial gains if the potential benefits from running tours and also from sale of produce from the roofgarden were included

A homological interpretation of the transverse quiver Grassmannians

In recent articles, the investigation of atomic bases in cluster algebras associated to affine quivers led the second-named author to introduce a variety called transverse quiver Grassmannian and the first-named and third-named authors to consider the smooth loci of quiver Grassmannians. In this paper, we prove that, for any affine quiver Q, the transverse quiver Grassmannian of an indecomposable representation M is the set of points N in the quiver Grassmannian of M such that Ext^1(N,M/N)=0. As a corollary we prove that the transverse quiver Grassmannian coincides with the smooth locus of the irreducible components of minimal dimension in the quiver Grassmannian.Comment: final version, 7 pages, corollary 1.2 has been modifie

Discovery of dumbbell-shaped Cs*He_n exciplexes in solid He 4

We have observed several new spectral features in the fluorescence of cesium atoms implanted in the hcp phase of solid helium following laser excitation to the 6$^{2}$P states. Based on calculations of the emission spectra using semiempirical Cs-He pair potentials the newly discovered lines can be assigned to the decay of specific Cs*He$_{n}$ exciplexes: an apple-shaped Cs$(A\Pi _{3/2})$He$_{2}$ and a dumbbell-shaped Cs$(A\Pi_{1/2})$He$_{n}$ exciplex with a well defined number $n$ of bound helium atoms. While the former has been observed in other enviroments, it was commonly believed that exciplexes with $n>2$ might not exist. The calculations suggest Cs$(A\Pi_{1/2})$He$_{6}$ to be the most probable candidate for that exciplex, in which the helium atoms are arranged on a ring around the waist of the dumbbell shaped electronic density distribution of the cesium atom.Comment: 4 pages, 4 figure

Will life find a way? Evolution of marine species under global change

Projections of marine biodiversity and implementation of effective actions for its maintenance in the face of current rapid global environmental change are constrained by our limited understanding of species’ adaptive responses, including transgenerational plasticity, epigenetics and natural selection. This special issue presents 13 novel studies, which employ experimental and modelling approaches to (i) investigate plastic and evolutionary responses of marine species to major global change drivers; (ii) ask relevant broad eco-evolutionary questions, implementing multiple species and populations studies; (iii) show the advantages of using advanced experimental designs and tools; (iv) construct novel model organisms for marine evolution; (v) help identifying future challenges for the field; and (vi) highlight the importance of incorporating existing evolutionary theory into management solutions for the marine realm. What emerges is that at least some populations of marine species have the ability to adapt to future global change conditions. However, marine organisms’ capacity for adaptation appears finite, due to evolutionary trade-offs and possible rapid losses in genetic diversity. This further corroborates the idea that acquiring an evolutionary perspective on how marine life will respond to the selective pressure of future global changes will guide us in better identifying which conservation efforts will be most needed and most effective

Cluster algebras of type A2(1)A_2^{(1)}

In this paper we study cluster algebras \myAA of type $A_2^{(1)}$. We solve the recurrence relations among the cluster variables (which form a T--system of type $A_2^{(1)}$). We solve the recurrence relations among the coefficients of \myAA (which form a Y--system of type $A_2^{(1)}$). In \myAA there is a natural notion of positivity. We find linear bases \BB of \myAA such that positive linear combinations of elements of \BB coincide with the cone of positive elements. We call these bases \emph{atomic bases} of \myAA. These are the analogue of the "canonical bases" found by Sherman and Zelevinsky in type $A_{1}^{(1)}$. Every atomic basis consists of cluster monomials together with extra elements. We provide explicit expressions for the elements of such bases in every cluster. We prove that the elements of \BB are parameterized by \ZZ^3 via their $\mathbf{g}$--vectors in every cluster. We prove that the denominator vector map in every acyclic seed of \myAA restricts to a bijection between \BB and \ZZ^3. In particular this gives an explicit algorithm to determine the "virtual" canonical decomposition of every element of the root lattice of type $A_2^{(1)}$. We find explicit recurrence relations to express every element of \myAA as linear combinations of elements of \BB.Comment: Latex, 40 pages; Published online in Algebras and Representation Theory, springer, 201

Prewetting transition on a weakly disordered substrate : evidence for a creeping film dynamics

We present the first microscopic images of the prewetting transition of a liquid film on a solid surface. Pictures of the local coverage map of a helium film on a cesium metal surface are taken while the temperature is raised through the transition. The film edge is found to advance at constant temperature by successive avalanches in a creep motion with a macroscopic correlation length. The creep velocity varies strongly in a narrow temperature range. The retreat motion is obtained only at much lower temperature, conforming to the strong hysteresis observed for prewetting transition on a disordered surface. Prewetting transition on such disordered surfaces appears to give rise to dynamical phenomena similar to what is observed for domain wall motions in 2D magnets.Comment: 7 pages, 3 figures, to be published in Euro.Phys.Let

Search for anisotropic effects of hcp solid helium on optical lines of cesium impurities

The anisotropic effect of a hcp 4He solid matrix on cesium atoms has been proposed as a tool to reveal the parity violating anapole moment of its nucleus. It should also result in splitting the D2 optical excitation line in a way depending on the light polarization. An experimental investigation has been set up using oriented hcp helium crystals in which cesium metal grains are embedded. Atoms are created by laser sputtering from this grains. Optical absorption spectra of the D2 line have been recorded in the temperature range of 1.0 to 1.4 K at liquid/solid coexistence pressure by monitoring the fluorescence on the D2 line at 950 nm. No significant effect of the light polarization has been found, suggesting a statistically isotropic disordered solid environment for the cesium atoms.Comment: The original publication will be available at http://www.springerlink.co

Temperature modulates the response of the thermophilous sea urchin Arbacia lixula early life stages to CO2-driven acidification

The increasing abundances of the thermophilous black sea urchin Arbacia lixula in the Mediterranean Sea are attributed to the Western Mediterranean warming. However, few data are available on the potential impact of this warming on A. lixula in combination with other global stressors such as ocean acidification. The aim of this study is to investigate the interactive effects of increased temperature and of decreased pH on fertilization and early development of A. lixula. This was tested using a fully crossed design with four temperatures (20, 24, 26 and 27 C) and two pH levels (pHNBS 8.2 and 7.9). Temperature and pH had no significant effect on fertilization and larval survival (2d) for temperature <27 C. At 27 C, the fertilization success was very low (<1%) and all larvae died within 2d. Both temperature and pH had effects on the developmental dynamics. Temperature appeared to modulate the impact of decreasing pH on the % of larvae reaching the pluteus stage leading to a positive effect (faster growth compared to pH 8.2) of low pH at 20 C, a neutral effect at 24 C and a negative effect (slower growth) at 26 C. These results highlight the importance of considering a range of temperatures covering today and the future environmental variability in any experiment aiming at studying the impact of ocean acidificatio