A review of biology, fisheries and population structure of Dentex dentex (Sparidae)

International audienceThe common dentex Dentex dentex (Linnaeus, 1758) is an iconic marine coastal fish in the Mediterranean Sea. It is a demersal sparid fish (0–200 m), that grows to a maximum length of 100 cm and a weight of 13 kg, with a relatively long life span (more than 20 years). As a high trophic level predator, it holds a key position in coastal marine food webs. The common dentex is of great economic importance for both artisanal (small-scale coastal fisheries) and recreational fishing. Despite its economic and ecological importance, scientific data on this species in its natural environment are still very scant. The global commercial catch of common dentex has fluctuated over the last 60 years on an interannual time scale, and has declined significantly since the 1990s. There are few data regarding fishing effort and total catch from recreational fishing for common dentex, but it appears that this species is particularly targeted by this activity. The common dentex is now classified as ‘‘vulnerable’’ in the Red List of Threatened Species in the Mediterranean Sea. This review summarizes the current literature on D. dentex in regard to biology, ecology, parasitology, population structure, commercial and recreational fishing, and management regulations. Future research directions to fill gaps in current knowledge are suggested

Comparison of 0- and 2-group otolith elemental signatures to discriminate Solea solea nurseries in the bay of biscay

International audienceThe common sole Solea solea (L.) is a commercially important and widely distributed flatfish of the North-East Atlantic. For the Bay of Biscay stock, sole nurseries display differences in terms of quantity and quality. In fine the measure of the quality of a habitat for juveniles of a particular species is expressed by the contribution to the recruitment into the adult population. Understanding this connectivity between juvenile and adult habitats, i.e. evaluating the contribution of each nursery to a single adult stock appears essential in terms of stock management. However, this critical link is still missing for the Bay of Biscay sole stock. Determining if nurseries could be discriminated using otolith elemental composition analysis constitutes the first step in evaluating the relative contribution of these nurseries into the adult stock. The aim of this study was to compare otolith elemental signatures of sole juveniles from two different ages (0-group and 2-group) captured at the same time in the six main nurseries of Bay of Biscay along the French Atlantic coast

Discrimination of Solea solea nurseries along the French Atlantic coast using otolith elemental signatures

International audienceOtolith elemental composition analysis has become a powerful tool to study fish population structure and connectivity between juvenile and adult habitats. The aim of the present study was to determine otolith elemental signature of sole from the main nurseries along the French Atlantic coast. 0-group sole juveniles (n=124) were sampled in 6 nurseries (embayed and estuarine) in the Bay of Biscay during September/October 2003. Multi-elemental composition was determined in whole otoliths using solution-based inductively coupled plasma mass spectrometry (ICP-MS). Elemental signatures differed significantly among sites, primarily due to variation in concentrations of the elements Li, Na, Mg, Mn, Cu, Sr, Rb and Ba. Discriminant function analysis (DFA) correctly classified over 68% of the individuals to their respective nursery based on otolith elemental signatures. This study constitutes the first step before evaluating the relative contribution of these different nurseries to the adult population at the scale of the Bay of Biscay. This approach might provide useful information in term of fisheries and coastal habitat management

New approach in the Mediterranean Sea on the understanding of the distribution and population dynamics of fishes’ post-larvae around Corsican coasts

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Absence of spatial genetic structure in common dentex (Dentex dentex Linnaeus, 1758) in the Mediterranean Sea as evidenced by nuclear and mitochondrial molecular markers.

The common dentex, Dentex dentex, is a fish species which inhabits marine environments in the Mediterranean and Northeast Atlantic regions. This is an important species from an ecological, economic and conservation perspective, however critical information on its population genetic structure is lacking. Most samples were obtained from the Mediterranean Sea (17 sites) with an emphasis around Corsica (5 sites), plus one Atlantic Ocean site. This provided an opportunity to examine genetic structuring at local and broader scales to provide science based data for the management of fishing stocks in the region. Two mitochondrial regions were examined (D-loop and COI) along with eight microsatellite loci. The COI data was combined with publicly available sequences and demonstrated past misidentification of common dentex. All markers indicated the absence of population genetic structure from the Bay of Biscay to the eastern Mediterranean Sea. Bayesian approaches, as well as the statistical tests performed on the allelic frequencies from microsatellite loci, indicated low differentiation between samples; there was only a slight (p = 0.05) indication of isolation by distance. Common dentex is a marine fish species with a unique panmictic population in the Mediterranean and likely in the Atlantic Ocean as well

Substrate Marking by an Invasive Ladybeetle: Seasonal Changes in Hydrocarbon Composition and Behavioral Responses

The multicolored Asian ladybeetle, Harmonia axyridis (Pallas), aggregates inside dwellings during the winter to survive the cold. Recent published reports have highlighted that overwintering individuals use hydrocarbon markings deposited on surfaces by conspecifics to orient toward aggregation sites. In the current study, monthly GC-MS analyses revealed seasonal modifications in the chemical profile of substrate markings deposited by moving individuals. The markings of overwintering ladybeetles contained larger proportions of heptacosadiene, nonacosadiene, hentriacontadienes, and methyl-nonacosanes, along with a lower proportion of heptacosene and nonacosene. This finding suggests the importance of the unsaturated and/or branched hydrocarbons in the H. axyridis aggregation process. Subsequently, we conducted behavioral assays to test whether (1) there is seasonal variation in the behavioral response of H. axyridis individuals toward substrate markings deposited by conspecifics in the same physiological state and (2) the observed behavioral modification is due to a change in ladybeetle sensitivity and/or a change in the chemical composition of the substrate marking. The results indicate that overwintering individuals exhibit a stronger ‘‘following’’ response toward conspecific substrate markings. This behavior is linked to both the physiological state of ladybeetles and the specific chemical profile of the marking biomolecules deposited under overwintering conditions

Cryptococcus neoformans Infections Differ Among Human Immunodeficiency Virus (HIV)–Seropositive and HIV-Seronegative Individuals: Results From a Nationwide Surveillance Program in France

International audienceAmong 1107 cryptococcosis cases from the French surveillance network (2005–2020), the proportion of HIV-seronegative individuals has recently surpassed that of HIV-seropositive individuals. We observed marked differences in patient characteristics, disease presentations, cryptococcal antigen results, infecting species, and mortality according to HIV serostatus