Environmental Influences on Juvenile Fish Abundances in a River-Dominated Coastal System

We investigated the influence of climatic and environmental factors on variations in juvenile abundances of marine fishes in a river-dominated coastal system of the north-central Gulf of Mexico, where an elevated primary productivity sustains fisheries of high economic importance. Fish were collected monthly with an otter trawl at three stations near Mobile Bay from 1982 to 2007. Fish sizes were used to isolate juvenile stages within the data set, and monthly patterns in juvenile fish abundance and size were then used to identify seasonal peaks for each species. The average numbers of juvenile fish collected during these seasonal peaks in each year were used as indices of annual juvenile abundances and were related to corresponding seasonal averages of selected environmental factors via a combination of principal components analysis and co-inertia analysis. Factors contributing the most to explain interannual variations in juvenile fish abundances were river discharge and water temperature during early spring–early summer, wind speed and North Atlantic Oscillation index during late fall–winter, and atmospheric pressure and wind speed during summer–fall. For example, juvenile abundances of southern kingfish Menticirrhus americanus during summer–fall were positively associated with atmospheric pressure and negatively associated with wind speed during this period. Southern kingfish juvenile abundances during late fall–winter were also negatively associated with wind speed during the same period and were positively associated with river discharge during early spring–early summer. Juvenile abundances of the Atlantic croaker Micropogonias undulatus during early spring–early summer were negatively associated with river discharge and North Atlantic Oscillation during late fall–winter. Overall, the importance of river discharge for many of the species examined emphasizes the major role of watershed processes for marine fisheries production in coastal waters of the north-central Gulf of Mexico

Multiscale analysis of factors that affect the distribution of sharks throughout the northern Gulf of Mexico

Identification of the spatial scale at which marine communities are organized is critical to proper management, yet this is particularly difficult to determine for highly migratory species like sharks. We used shark catch data collected during 2006–09 from fishery-independent bottom-longline surveys, as well as biotic and abiotic explanatory data to identify the factors that affect the distribution of coastal sharks at 2 spatial scales in the northern Gulf of Mexico. Centered principal component analyses (PCAs) were used to visualize the patterns that characterize shark distributions at small (Alabama and Mississippi coast) and large (northern Gulf of Mexico) spatial scales. Environmental data on temperature, salinity, dissolved oxygen (DO), depth, fish and crustacean biomass, and chlorophyll-a (chl-a) concentration were analyzed with normed PCAs at both spatial scales. The relationships between values of shark catch per unit of effort (CPUE) and environmental factors were then analyzed at each scale with co-inertia analysis (COIA). Results from COIA indicated that the degree of agreement between the structure of the environmental and shark data sets was relatively higher at the small spatial scale than at the large one. CPUE of Blacktip Shark (Carcharhinus limbatus) was related positively with crustacean biomass at both spatial scales. Similarly, CPUE of Atlantic Sharpnose Shark (Rhizoprionodon terraenovae) was related positively with chl-a concentration and negatively with DO at both spatial scales. Conversely, distribution of Blacknose Shark (C. acronotus) displayed a contrasting relationship with depth at the 2 scales considered. Our results indicate that the factors influencing the distribution of sharks in the northern Gulf of Mexico are species specific but generally transcend the spatial boundaries used in our analyses

FE modelling of bainitic steels using crystal plasticity

International audienceModels classically used to describe the probability of brittle fracture in nuclear power plants are written on a macroscale. Physical phenomena are not naturally captured by this type of approach, so that the application of the models far from their identification domain (temperature history, loading path) may become questionable. To improve the quality of the prediction of resistance and life time, microstructural information, describing the heterogeneous character of the material and its deformation mechanisms has to be taken into consideration. The purpose of the paper is to propose a model able to describe local stress and strain fields in 16MND5 bainitic steel. These data will then be used as critical variables for multiscale failure models. The microstructure of 16MND5 steel is made of bainitic packets coming from former austenitic grains, which are not randomly oriented. Knowing the macroscopic stress is thus not sufficient to describe the stress-strain state in ferrite. An accurate model must take into account the actual microstructure, in order to provide realistic local stress and strain fields. After providing some observations and the analysis of the bainitic microstructure, the paper shows a quantitative model of the morphology and the crystallography, then a finite element analysis involving crystal plasticity

Characteristics and outcome of patients with low-/intermediate-risk acute promyelocytic leukemia treated with arsenic trioxide - an international collaborative study

The aim of this study was to characterize a large series of 154 patients with acute promyelocytic leukemia (APL; median age, 53 years; range, 18-90 years) and evaluate real-life outcome after up-front treatment with arsenic trioxide (ATO) and alltrans retinoic acid (ATRA). All patients were included in the prospective NAPOLEON registry (NCT02192619) between 2013 and 2019. APL was de novo in 91% (n=140) and therapy-related in 9% (n=14); 13% (n=20) were older than 70 years. At diagnosis bleeding/hemorrhage was present in 38% and thrombosis in 3%. Complete remission was achieved in 152 patients (99%), whereas two patients (1%) experienced induction death within 18 days after start of therapy. With a median follow-up of 1.99 years (95%-CI, 1.61-2.30 years) 1-year and 2-years overall survival (OS) rates were 97% (95%-CI, 94-100%) and 95% (95%-CI, 91-99%), respectively. Age above 70 years was associated with a significantly shorter OS (P<0.001) as compared to younger patients. So far no relapses were observed. Six patients (4%) died in CR after in median 0.95 years after diagnosis (range, 0.18-2.38 years). Our data confirm the efficiency and durability of ATO/ATRA in the primary management of adult low-/ intermediate-risk APL patients in the real life setting, irrespective of age

Geometric morphometrics as a tool for identifying emperor fish (Lethrinidae) larvae and juveniles

The aim of this study was to evaluate the efficiency of geometric morphometrics for describing the body shape of fish larvae and juveniles, and identifying them to species, in comparison with traditional linear measurements. Species of emperor fishes (Perciformes: Lethrinidae, genus Lethrinus) were chosen as the model group, as the late larval and early juvenile stages in this genus are particularly difficult to identify. Forty-five individuals of different species of Lethrinus were collected from the south-western lagoon of New Caledonia between May 2005 and March 2006. The individuals were first identified to species by their partial cytochrome-b gene sequence. They were then morphologically characterized using eight linear measurements and 23 landmarks recorded on digital photographs. Except for a small proportion of individuals, geometric morphometrics gave better results to distinguish the different species than linear measurements. A 'leave one out' approach confirmed the nearly total discrimination of recently settled Lethrinus genivittatus and Lethrinus nebulosus, whereas traditional identification keys failed to distinguish them. Therefore, geometric morphometrics is a promising tool for identifying fish larvae and juveniles to species. An effective approach would require building image databases of voucher specimens associated with their DNA barcodes. These images could be downloaded by the operator and processed with the specimens to be identified

Cross-Shore, Seasonal, and Depth-Related Structure of Ichthyoplankton Assemblages in Coastal Alabama

Investigations of the spatial and temporal structure of larval fish assemblages are essential for a better understanding of the dynamics of fish populations and their resilience to environmental change. This study provides an original typology of the spatial, seasonal, and depth-related structure of ichthyoplankton assemblages collected along a 77-km cross-shore gradient in Alabama coastal waters. This typology is based on a depth-discrete ichthyoplankton survey conducted across multiple years at a high spatial and temporal resolution in the northern Gulf of Mexico. A total of 350,766 larvae were collected, among which \u3e95% could be identified to families. The total density of fish larvae was significantly higher inshore, whereas the number of families increased offshore. Multivariate regression trees and Dufrêne–Legendre indices were used to identify seven assemblages dominated by different families of larvae. These assemblages were primarily structured by distance from the shore, followed by season and depth, and were associated with different water masses characterized by distinct temperature and salinity conditions. Families Clupeidae, Bregmacerotidae, Synodontidae, Scombridae, and Ophidiidae were typical offshore, whereas families Engraulidae, Gobiidae, and Gobiesocidae were typical inshore. These observed spatial distributions likely reflected interactions between adult spawning behaviors and oceanographic processes, in particular the influence of the Mobile River. Our results thus confirm existing lines of evidence suggesting that riverine influences play a major role in fish population dynamics along the Alabama inner shelf. For many families, the observed seasonal distributions were largely consistent with the results of previous studies conducted at smaller spatial resolution in the area. However, our large-scale, high-resolution, cross-shore design clearly improved the detection of seasonal variations for inshore and offshore taxa otherwise rarely collected

Evaluation of the Taxonomic Sufficiency Approach for Ichthyoplankton Community Analysis

Ichthyoplankton identification is a time-consuming task, and often larvae cannot be identified to species due to a lack of adequate early life history descriptions. As a result, ichthyoplankton assemblage data are often analyzed at the family level, which results in a loss of taxonomic resolution, or at mixed taxonomic levels (e. g. family, genus and species combined), which can lead to difficulties in interpretation of results when a single species is included in multiple taxonomic groupings. The taxonomic sufficiency (TS) approach has been used extensively in other disciplines (e. g. benthic marine macrofauna) to address similar analytical constraints, but to date this method has not been rigorously examined for ichthyoplankton studies. In this study, an ichthyoplankton data set collected in the northern Gulf of Mexico was proportioned into 3 data subsets with varying levels of taxonomic resolution: (1) species level only; (2) species, genus and family levels; and (3) combined taxonomic levels. Comparisons were made for assemblage metrics (larval density, richness and diversity) calculated for each taxonomic subset, as well as multivariate analyses of temporal variations characterizing ichthyoplankton assemblages. Genus- and species-level similarity matrices were highly correlated, which suggests analyses at the genus level could serve as a good proxy for species when examining assemblage diversity. Multivariate results for seasonal patterns were similar among family-, genus- and species-level analyses. The common approach of analyzing ichthyoplankton assemblages at mixed taxonomic levels, however, is not as statistically rigorous as single taxonomic-level analyses

Parasite infection reflects host genetic diversity among non-native populations of pumpkinseed sunfish in Europe

International audienceSpecies introductions often coincide with loss of genetic diversity and natural enemies. Anthropogenic translocation of the North-American pumpkinseed Lepomis gibbosus (L., 1758) (Centrarchidae) and its further spread have resulted in recent species establishment in most European countries. This study determines genetic differentiation of non-native European pumpkinseed populations and identifies how their genetic structure relates to the distribution and abundance of parasite species. Microsatellite analysis indicated presence of three genetic lineages, which were well supported by discriminant analysis based on parasite abundance data. The first lineage clustered pumpkinseed populations from northern and southern France and showed high allelic richness, heterozygosity and parasite richness. The second included populations along the ‘‘Southern invasion corridor’’ connecting the rivers Rhine, Main and Danube. The fish exhibited low to high genetic and parasite diversity and generally high parasite abundance. The third lineage clustered populations with low genetic and parasite diversity, located in Portuguese reservoirs and water bodies along the upper Elbe. Parasite species richness was significantly associated with host microsatellite heterozygosity and allelic richness, a trend partially affected by richness of North-American parasites. Furthermore, our results indicate that parasite community composition may serve as a useful biological tool to discriminate non-native fish populations and their inter-relationships