Explore the vast range of titles available.

Environmental gradients and their influence on benthic community structure vary over different spatial scales; yet, few studies in the Arctic have attempted to study the influence of environmental gradients of differing spatial scales on megabenthic communities across continental-scales. The current project studied for the first time how megabenthic community structure is related to several environmental factors over 2000 km of the Canadian Arctic, from the Beaufort Sea to northern Baffin Bay. Faunal trawl samples were collected between 2007 and 2011 at 78 stations from 30 to 1000 m depth and patterns in biomass, density, richness, diversity, and taxonomic composition were examined in relation to indirect/spatial gradients (e.g., depth), direct gradients (e.g., bottom oceanographic variables), and resource gradients (e.g., food supply proxies). Six benthic community types were defined based on their biomass-based taxonomic composition. Their distribution was significantly, but moderately, associated with large-scale (100-1000 km) environmental gradients defined by depth, physical water properties (e.g., bottom salinity), and meso-scale (10-100 km) environmental gradients defined by substrate type (hard vs. soft) and sediment organic carbon content. We did not observe a strong decline of bulk biomass, density and richness with depth or a strong increase of those community characteristics with food supply proxies, contrary to our hypothesis. We discuss how local- to meso-scale environmental conditions, such as bottom current regimes and polynyas, sustain biomass-rich communities at specific locations in oligotrophic and in deep regions of the Canadian Arctic. This study demonstrates the value of considering the scales of variability of environmental gradients when interpreting their relevance in structuring of communities.

Idiopathic hypersomnia (IH), characterized by an excessive day-time sleepiness, a prolonged total sleep time on 24 h and/or a reduced sleep latency, affects 1 in 2000 individuals from the general population. However, IH remains underdiagnosed and inaccurately treated despite colossal social, professional and personal impacts. The pathogenesis of IH is poorly known, but recent works have suggested possible alterations of phototransduction. In this context, to identify biomarkers of IH, we studied the Post-Illumination Pupil Response (PIPR) using a specific pupillometry protocol reflecting the melanopsin-mediated pupil response in IH patients with prolonged total sleep time (TST > 660 min) and in healthy subjects. Twenty-eight patients with IH (women 86%, 25.4 year-old ± 4.9) and 29 controls (women 52%, 27.1 year-old ± 3.9) were included. After correction on baseline pupil diameter, the PIPR was compared between groups and correlated to sociodemographic and sleep parameters. We found that patients with IH had a lower relative PIPR compared to controls (32.6 ± 9.9% vs 38.5 ± 10.2%, p = 0.037) suggesting a reduced melanopsin response. In addition, the PIPR was not correlated to age, chronotype, TST, nor depressive symptoms. The melanopsin-specific PIPR may be an innovative trait marker of IH and the pupillometry might be a promising tool to better characterize hypersomnia.

Sea pens are ecologically important coral species in deep, cold-water ecosystems in the Northwest Atlantic, where they form dense aggregations. Sea pens are threatened by bottom-contact fishing gears and potentially by global change drivers, including ongoing ocean acidification. To better understand their fundamental biology and how these environmental threats may affect sea pens, information on their age structure, growth rates, and level of mineralization is required. We evaluate the age of the sea pens Pennatula aculeata (Danielssen 1860) and Ptilella grandis (Ehrenberg 1834) from two regions of contrasting densities in the Estuary and the Gulf of St. Lawrence. In addition, we characterized relationships between the length, diameter, age, growth rate, and mineralization status of sea pens central stem, known as the rachis. We revealed interspecific differences in age, length, diameter and growth rates, as well as intraspecific (regional) differences in age, length and diameter. On average, the mineral content of longer and older individuals was lower, especially in the upper extremity of the rachis, suggesting a change in mineralization during ontogeny that may have evolved to guarantee greater flexibility of the parts more exposed to currents. There were also interspecific differences in mineralization status, with P. aculeata generally being more highly mineralized.

We analyzed stable carbon and nitrogen isotope values (δ 13 C and δ 15 N, respectively) for pan-Arctic coastal primary producers and consumers to detect large-scale regional trends both temporally and spatially. To facilitate comparison, we grouped coastal habitats into fjords, lagoons, shelves, and straits as four “coastscapes”. We gathered over 12,000 rows of data collected over 24 years (between 1999 and 2022) from 34 different field campaigns across the coastal Arctic (63 to 81°N and 177°W to 33°E). Our goal was to examine the isotopic patterns in pelagic and sediment particulate organic matter (pPOM and sPOM, respectively) and four consumer groups (deposit feeders, opportunists/scavengers, predators, and suspension feeders) among the four coastscapes. We found that despite the enormous spatial range of data, both pPOM and sPOM became 2.1‰ and 2.2‰ more 13 C-depleted per decade, respectively, with parallel decreases in the δ 13 C values in consumers. The significant decrease is likely attributed to the increased contributions of 13 C-depleted terrestrial organic matter across the Arctic coasts from freshwater inputs and coastal erosion in concert with diminishing sea ice that supports sympagic microalgae. Across all Arctic coastscapes, consumer groups exhibited overlapping isotopic composition, notably with wide δ 13 C ranges that indicated assimilation of multiple organic matter sources, including terrestrial organic matter, organic matter derived from marine phytoplankton and sea ice algae, macroalgae, and potentially benthic microalgae or degraded organic matter. This consistent pattern across coastscapes provides evidence of the trophic plasticity possessed by Arctic consumers, how coastal food webs respond to climate warming, and the signature of terrestrialization imprinted on the pan-Arctic coastal isoscape.

Population dynamics and the way abundance fluctuates over time may be key determinants of the invasion success of an introduced species. Fine-scale temporal monitoring of invasive species is rarely carried out due to the difficulties in collecting data regularly and over a long period. Thanks to the collaboration of an amateur naturalist, a unique dataset on the abundance of the invasive land flatworm Obama nungara was obtained during a 4-year survey of a French private garden, where up to 1585 O. nungara were recorded in 1 month. Daily monitoring data revealed high population size fluctuations that may be explained by meteorological factors as well as intra-and inter-specific interactions. Bayesian modeling confirmed that O. nungara's abundance fluctuates depending on temperature, humidity, and precipitation. Population growth seems to be favored by mild winters and precipitation while it is disadvantaged by drought. These exogenous factors affect both directly this species, which is sensitive to desiccation, and indirectly since they are known to affect the populations of its prey (earthworms and terrestrial gastropods). We also suggested the important resilience of O. nungara population in this site, which was able to recover from a drastic demographic bottleneck due to a severe drought, as well to systematic removal by the owner of the site. These findings highlight the potentially high invasiveness of O. nungara and raise concerns about the major threat these invasive flatworms pose to the populations of their prey.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

DNA metabarcoding is a powerful approach for assessing biodiversity and unravelling trophic interactions, particularly in the context of biological invasions where introduced predators may impact native communities. However, the analysis of predator digestive contents with DNA metabarcoding poses technical challenges including the specificity of primers used to amplify the target DNA, amplification bias and contamination issues, which must be carefully considered when working on new taxa. This study addresses these challenges by developing and validating a methodology for assessing the diversity of terrestrial gastropods predated by the exotic flatworm Obama nungara . Specifically, an optimized primer pair providing taxonomic resolution for at least 40 gastropod species and genetic lineages, including taxonomically complex and diverse slug genera such as Arion and Deroceras is proposed. The primer pair was optimized through in silico predictions, laboratory controls, and field testing. Mock communities, laboratory-fed individuals, and technical replicates from the field were used as metabarcoding controls to calibrate filter thresholds for Operational Taxonomic Units. Preliminary field results revealed significant dietary diversity in O. nungara , suggesting a broad feeding spectrum. Beyond O. nungara , the primers and the assay developed here can also be applied to study the diets of other terrestrial predators or to detect gastropods in environmental DNA samples, providing a useful tool for ecological and conservation research.

Previous surveys of the gut microbiota of termites have been limited to the worker caste. Termite gut microbiota has been well documented over the last decades and consists mainly of lineages specific to the gut microbiome which are maintained across generations. Despite this intimate relationship, little is known of how symbionts are transmitted to each generation of the host, especially in higher termites where proctodeal feeding has never been reported. The bacterial succession across life stages of the wood-feeding higher termite Nasutitermes arborum was characterized by 16S rRNA gene deep sequencing. The microbial community in the eggs, mainly affiliated to Proteobacteria and Actinobacteria, was markedly different from the communities in the following developmental stages. In the first instar and last instar larvae and worker caste termites, Proteobacteria and Actinobacteria were less abundant than Firmicutes, Bacteroidetes, Spirochaetes, Fibrobacteres and the candidate phylum TG3 from the last instar larvae. Most of the representatives of these phyla (except Firmicutes) were identified as termite-gut specific lineages, although their relative abundances differed. The most salient difference between last instar larvae and worker caste termites was the very high proportion of Spirochaetes, most of which were affiliated to the Treponema Ic, Ia and If subclusters, in workers. The results suggest that termite symbionts are not transmitted from mother to offspring but become established by a gradual process allowing the offspring to have access to the bulk of the microbiota prior to the emergence of workers, and, therefore, presumably through social exchanges with nursing workers.

It is long established that queens of social insects, including termites, maintain their reproductive dominance with queen primer pheromones (QPPs). Yet, the QPP chemistry has only been elucidated in a single species of lower termites. By contrast, the most diversified termite family Termitidae (higher termites), comprising over 70% of termite species, has so far resisted all attempts at QPP identification. Here, we show that the queen- and egg-specific sesquiterpene (3 R ,6 E )-nerolidol acts as the QPP in the higher termite Embiratermes neotenicus . This species has a polygynous breeding system, in which the primary queen is replaced by multiple neotenic queens of parthenogenetic origin. We demonstrate that (3 R ,6 E )-nerolidol suppresses the development of these parthenogenetic queens and thus mimics the presence of mature queen(s). It acts as an airborne signal and may be used to optimize the number of queens, thus being the key regulatory element in the special breeding system of E. neotenicus . A queen primer pheromone in higher termites is identified and shown to control the development of new queens in the colony, and acts as an airborne signal detected via olfaction.