The great melting pot. Common sole population connectivity assessed by otolith and water fingerprints

Quantifying the scale and importance of individual dispersion between populations and life stages is a key challenge in marine ecology. The common sole (Solea solea), an important commercial flatfish in the North Sea, Atlantic Ocean and the Mediterranean Sea, has a marine pelagic larval stage, a benthic juvenile stage in coastal nurseries (lagoons, estuaries or shallow marine areas) and a benthic adult stage in deeper marine waters on the continental shelf. To date, the ecological connectivity among these life stages has been little assessed in the Mediterranean. Here, such an assessment is provided for the first time for the Gulf of Lions, NW Mediterranean, based on a dataset on otolith microchemistry and stable isotopic composition as indicators of the water masses inhabited by individual fish. Specifically, otolith Ba/Ca and Sr/Ca profiles, and delta C-13 and delta O-18 values of adults collected in four areas of the Gulf of Lions were compared with those of young-of-the-year collected in different coastal nurseries. Results showed that a high proportion of adults (>46%) were influenced by river inputs during their larval stage. Furthermore Sr/Ca ratios and the otolith length at one year of age revealed that most adults (similar to 70%) spent their juvenile stage in nurseries with high salinity, whereas the remainder used brackish environments. In total, data were consistent with the use of six nursery types, three with high salinity (marine areas and two types of highly saline lagoons) and three brackish (coastal areas near river mouths, and two types of brackish environments), all of which contributed to the replenishment of adult populations. These finding implicated panmixia in sole population in the Gulf of Lions and claimed for a habitat integrated management of fisherie

Mass marking in European sturgeon: chap. 25

International audienceWhen assessing stocking programmes, there needs to be discrimination between stocked fish and wild fish, and between different groups (i.e., cohorts, release sites) within stocked fish. Few methods are available for marking a large number of fish at an early stage with minimum handling. Chemical mass marking matches these prerequisites, and this method has been retained for the European sturgeon. Because the sampling has no adverse effects on individuals, marking efficiency has been checked on the pectoral fin ray. After qualified results were recorded in 2007 and 2008, this led to the testing of the possible effect of chemical or size/age on marking efficiency and mark quality. A tetracycline bath at 600 ppm for 8 h has given satisfactory results in fish not younger than 4 months

Influence of consolidation methods on the recrystallization kinetics of a Fe–14Cr based ODS steel

International audienceThe recrystallization behavior during thermal annealing with or without prior cold work has been investigated in a 14%Cr ODS steel consolidated by two different methods, hot extrusion (HE) and hot isostatic pressing (HIP). We show that a 1400 degrees C-1 h annealing induces an increase of the oxide nanoparticles radius from 1.3 to 3 nm, however the grain size remain stable despite a recovery of sub-grain boundaries for the hot extruded material. When pre-deformation is applied before annealing, almost full recrystallization can be achieved on the HE ODS steel. In this study, we show recrystallization after 40% cold deformation and annealing 30 min at 1450 degrees C together with coarsening of oxide particles. At lower temperature and higher pre-deformation (70%-1150 degrees C/30 min), we show that recrystallization can be achieved without change of the oxide size distribution. We show that due to a lower initial dislocation density, recrystallization is strongly delayed, by at least 250 degrees C, in the HIP material. Finally, we show that the evolution of the size of the oxide precipitates is controlled by the time and temperature of annealing and are independent on the pre-deformation and occurrence of recrystallization. (C) 2016 Elsevier B.V. All rights reserved

Subdivisions in digraphs of large out-degree or large dichromatic number

In 1985, Mader conjectured the existence of a function f such that every digraph with minimum out-degree at least f ( k ) contains a subdivision of the transitive tournament of order k . This conjecture is still completely open, as the existence of f ( 5 ) remains unknown. In this paper, we show that if D is an oriented path, or an in-arborescence (i.e., a tree with all edges oriented towards the root) or the union of two directed paths from x to y and a directed path from y to x , then every digraph with minimum out-degree large enough contains a subdivision of D . Additionally, we study Mader's conjecture considering another graph parameter. The dichromatic number of a digraph D is the smallest integer k such that D can be partitioned into k acyclic subdigraphs. We show that any digraph with dichromatic number greater than 4 m ( n − 1 ) contains every digraph with n vertices and m arcs as a subdivision. We show that any digraph with dichromatic number greater than 4 m ( n − 1 ) contains every digraph with n vertices and m arcs as a subdivision

Powers of paths in tournaments

In this short note we prove that every tournament contains the k-th power of a directed path of linear length. This improves upon recent results of Yuster and of Girão. We also give a complete solution for this problem when k = 2, showing that there is always a square of a directed path of length [2n/3] − 1, which is best possible