A flexible bio-inspired hierarchical model for analyzing musical timbre

A flexible and multipurpose bio-inspired hierarchical model for analyzing musical timbre is presented in this paper. Inspired by findings in the fields of neuroscience, computational neuroscience, and psychoacoustics, not only does the model extract spectral and temporal characteristics of a signal, but it also analyzes amplitude modulations on different timescales. It uses a cochlear filter bank to resolve the spectral components of a sound, lateral inhibition to enhance spectral resolution, and a modulation filter bank to extract the global temporal envelope and roughness of the sound from amplitude modulations. The model was evaluated in three applications. First, it was used to simulate subjective data from two roughness experiments. Second, it was used for musical instrument classification using the k-NN algorithm and a Bayesian network. Third, it was applied to find the features that characterize sounds whose timbres were labeled in an audiovisual experiment. The successful application of the proposed model in these diverse tasks revealed its potential in capturing timbral information

Impacts of intraguild predation on Arctic copepod communities

Communities of large copepods form an essential hub of matter and energy fluxes in Arctic marine food webs. Intraguild predation on eggs and early larval stages occurs among the different species of those communities and it has been hypothesized to impact its structure and function. In order to better understand the interactions between dominant copepod species in the Arctic, we conducted laboratory experiments that quantified intraguild predation between the conspicuous and omnivorous Metridia longa and the dominant Calanus hyperboreus. We recorded individual egg ingestion rates for several conditions of temperature, egg concentration, and alternative food presence. In each of these experiments, at least some females ingested eggs but individual ingestion rates were highly variable. The global mean ingestion rate of M. longa on C. hyperboreus eggs was 5.8 eggs ind−1 d−1, or an estimated 37% of M. longa daily metabolic need. Among the different factors tested and the various individual traits considered (prosome length, condition index), only the egg concentration had a significant and positive effect on ingestion rates. We further explored the potential ecological impacts of intraguild predation in a simple 1D numerical model of C. hyperboreus eggs vertical distribution in the Amundsen Gulf. Our modeling results showed an asymmetric relationship in that M. longa has little potential impact on the recruitment of C. hyperboreus (<3% egg standing stock removed by IGP at most) whereas the eggs intercepted by the former can account for a significant portion of its metabolic requirement during winter (up to a third)

Defining what constitutes a reliable dataset to test for hybridization and introgression in marine zooplankton: Comment on Choquet et al. 2020 “No evidence for hybridization between Calanus finmarchicus and C. glacialis in a subarctic area of sympatry”

The article ‘No evidence for hybridization between Calanus finmarchicus and C. glacialis in a subarctic area of sympatry’ (Choquet et al. 2020) concludes that “no evidence supports a potential for hybridization between C. finmarchicus and C. glacialis”. We argue that the InDel markers used by Choquet et al. (2020) may have limited capacity to detect admixed genotypes between C. finmarchicus and C. glacialis due to an inappropriate choice of reference sample for each species during the marker development. We first review terms and concepts used in genetic classification using reference samples and describe problems associated with the selection of genetic markers in the context of possible hybridization. We reanalyze InDel genotypes provided with Choquet et al. (2017) and identified an admixed individual. We then contrast methods used by Choquet et al. (2017) and Parent et al. (2012) and explain how Parent et al. (2012) developed microsatellite markers capable of discriminating admixed genotypes from parental species. In this comment, we have identified a major issue that must be considered when selecting reference samples in the context of testing for possible hybridization.publishedVersio

Spatio-temporal patterns in fin whale <i>Balaenoptera physalus</i> habitat use in the northern Gulf of St. Lawrence

Significant ecosystem changes in the Gulf of St. Lawrence (GSL), Canada, have had far-reaching effects at all trophic levels. The abundance of fin whales Balaenoptera physalus has declined significantly in the northern GSL over the past decade. This study aimed to test the hypothesis that the observed decline was correlated to changing environmental conditions. Cetacean sightings data from 292 surveys, resulting in 2986 fin whale encounters from 2007 to 2013, were used to fit 2 separate generalised additive models in terms of (1) bathymetric and oceanographic variables (the proxy model) and (2) modelled krill biomass (the prey model). The concept of ‘handling time’ was introduced to correct for time off search effort, applicable to other studies relying on opportunistically sampled data. While a positive correlation between krill biomass and fin whale numbers was found, the performance of the proxy model (24.2% deviance explained) was overall better than the prey model (11.8%). Annual predictive maps derived from the final proxy model highlighted 2 key areas with recurrently high relative fin whale abundance and a significant overlap with shipping lanes. While both models provided evidence for an annual decline in relative fin whale abundance, static bathymetric features were the most important predictors of habitat use, and no correlation between dynamic variables and the decline was found. High resolution prey data and a better understanding of the feeding ecology of fin whales are proposed to further investigate the predator-prey relationship and decline of fin whales in the GSL

Recrutement des poissons dans le fjord du Saguenay

La faune ichtyologique du fjord du Saguenay est composée de plus de 60 espèces de poissons marins, diadromes et dulcicoles dont plusieurs font l’objet d’une pêche récréative comme l’éperlan arc-en-ciel anadrome (Osmerus mordax), le sébaste (Sebastes spp.), la morue franche (Gadus morhua), la morue ogac (Gadus ogac) et le flétan du Groenland (Reinhardtius hippoglossoides). On ignore si le recrutement des poissons marins exploités par la pêche récréative dans le Saguenay dépend de la production des stocks locaux ou des échanges avec les populations de l’estuaire du Saint-Laurent. Nous avons donc étudié la distribution spatio-temporelle de l’ichtyoplancton dans le fjord du Saguenay afin d’identifier les zones de production, de rétention et d’advection larvaires dans le but d’y préciser les mécanismes de recrutement des stocks de poissons. L’ichtyoplancton a été échantillonné à 21 stations sur le fjord du Saguenay à six occasions, de mai à octobre 2004, et à cinq occasions, de juin à septembre 2005. Les résultats montrent que le recrutement du capelan et de l’éperlan arc‑en‑ciel anadrome repose sur la production et la rétention des larves dans le fjord du Saguenay. Cependant, le recrutement des sébastes et des morues dépendrait de l’immigration de juvéniles en provenance de l’estuaire du Saint-Laurent. Ces résultats sont supportés par une revue des résultats des études antérieures sur les poissons du fjord du Saguenay. L’étude des mécanismes de recrutement des stocks de poissons du fjord du Saguenay favorise l’exploitation durable de ces ressources halieutiques conformément à la mission de Pêches et Océans Canada et dans le respect du programme de conservation du parc marin du Saguenay‑Saint-Laurent.In the Saguenay Fjord, the fish community is composed of more than 60 marine, diadromous and freshwater species, including many species exploited by the winter sport fishery such as the rainbow smelt (Osmerus mordax), redfish (Sebastes spp.), Atlantic cod (Gadus morhua), Greenland cod (Gadus ogac), and Greenland halibut (Reinhardtius hippoglossoides). We do not know if the recruitment of the fish species exploited by the winter sport fishery depends on the local production of recruits in the Saguenay Fjord or on exchanges with the St. Lawrence Estuary populations. Hence, we measured the spatio-temporal distribution of ichthyoplankton in the Fjord to identify zones of larval production, retention or advection, in order to investigate the recruitment mechanisms of these stocks. We sampled ichthyoplankton at 21 stations on six occasions, from May to October 2004, and on five occasions, from June to September 2005. Results indicated that the recruitment of capelin (Mallotus villosus) and of the anadromous rainbow smelt (Osmerus mordax) relied on the local production and retention of larvae within the Fjord. However, the recruitment of redfish (Sebastes spp.) and cods (Gadus spp.) depended on the immigration of juveniles from the St. Lawrence Estuary. Our results are corroborated by a review of previous studies of these fish populations. Studying the recruitment mechanisms of fish populations in the Saguenay Fjord supports a sustainable exploitation of these locally important fisheries resources, in accordance with the mission of Fisheries and Oceans Canada and consistent with the conservation program of the Saguenay St. Lawrence Marine Park

Absorption and metabolism of conjugated α-linolenic acid given as free fatty acids or triacylglycerols in rats

Background: Conjugated linoleic acid (CLA) is a group of polyunsaturated fatty acids which have been extensively studied in the past two decades. However, conjugated octadecatrienoic acid such as cis-9,trans-11,cis-15 and cis-9,trans-13,cis-15, recently identified, have not been extensively investigated. This work presents bioavailability and tissue incorporation of a mixture of conjugated octadecatrienoic (CLnA) acids ingested as free fatty acids (FFA) and triacylglycerols (TAG). Results: Male Wistar rats were fed rumenic acid (RA: cis-9,trans-11 18:2) and a CLnA mixture (cis9,trans-11,cis-15 18:3 and cis-9,trans-13,cis-15 18:3) as FFA and TAG for 8 days. RA and CLnA were both totally absorbed when given as FFA as well as TAG. Both isomers of CLnA as FFA or TAG were incorporated into neutral lipids. Metabolites up to 22:6 conjugated isomers were present in liver and plasma phospholipids of rats fed the CLnA diets. Conclusion: Finally, CLnA are as well absorbed as RA in vivo and their incorporation into tissues and bioconversion are similar when ingested as FFA or as TAG

Voracious planktonic hydroids: unexpected predatory impact on a coastal marine ecosystem

Hydroids are typically attached, benthic cnidarians that feed on a variety of small prey. During sampling on Georges Bank in spring 1994, we found huge numbers of hydroids suspended in the plankton. They fed on young stages of copepods that are an important prey for fish, as well as on young fish themselves. Two independent methods were used to estimate feeding rates of the hydroids; both indicate that the hydroids are capable of consuming from 50% to over 100% of the daily production of young copepods. These results suggest that hydroids can have a profound effect on the population dynamics of zooplankton and young fish on Georges Bank

Biogeography of key mesozooplankton species in the North Atlantic and egg production of Calanus finmarchicus

-Here we present a new, pan-North-Atlantic compilation of data on key mesozooplankton species, including the most important copepod, Calanus finmarchicus. Distributional data of eight representative zooplankton taxa, from recent (2000–2009) Continuous Plankton Recorder data, are presented, along with basin-scale data of the phytoplankton colour index. Then we present a compilation of data on C. finmarchicus, including observations of abundance, demography, egg production and female size, with accompanying data on temperature and chlorophyll