44 research outputs found
Variable predatorâprey relations in zooplankton overwintering in subarctic fjords
Zooplankton predatorâprey relations in northern Norwegian fjords are highly variable in time and space, and the mechanisms driving this variability are still poorly understood. Replicate Juday net sampling in October and February from 1983 to 2005, which included five repeated tows from bottom to surface, was conducted in Saltfjord and Mistfjord, northern Norway. The time-series provided evidence of in situ variability in species abundance, as well as seasonal and interannual changes in standing stock abundance. The shallow sill of one fjord caused accumulation of coastal water in the fjordâs basin, while the other fjordâs deeper sill selected denser water of Atlantic origin from the same open shelf habitat. The selective advection caused differences in the immigration of species recruiting to the fjordsâ specific overwintering communities of zooplankton. Statistical analyses of the cumulated replicate data indicated significant in situ variability in the spatial density of species. Cases with an abundance of carnivores relating positively to other species probably resulted from the carnivoresâ attraction to patches with concentrations of prey. Interspecific negative density relations likely indicated either predator avoidance or substantial trophic activity during the sampling. During years of high abundance, some wintering stocks of carnivores evidently reduced the local stocks of overwintering prey. We conclude that predatorâprey interactions and stock variability in Subarctic fjords result from complex bio-geophysical interactions that occur on the scales of local habitats and basin-scale population systems.publishedVersio
A major Calanus finmarchicus overwintering population inside a deep fjord in northern Norway: implications for cod larvae recruitment success
Paid Open Acces
Super-Aggregations of Krill and Humpback Whales in Wilhelmina Bay, Antarctic Peninsula
Ecological relationships of krill and whales have not been explored in the Western Antarctic Peninsula (WAP), and have only rarely been studied elsewhere in the Southern Ocean. In the austral autumn we observed an extremely high density (5.1 whales per km2) of humpback whales (Megaptera novaeangliae) feeding on a super-aggregation of Antarctic krill (Euphausia superba) in Wilhelmina Bay. The krill biomass was approximately 2 million tons, distributed over an area of 100 km2 at densities of up to 2000 individuals mâ3; reports of such âsuper-aggregationsâ of krill have been absent in the scientific literature for >20 years. Retentive circulation patterns in the Bay entrained phytoplankton and meso-zooplankton that were grazed by the krill. Tagged whales rested during daylight hours and fed intensively throughout the night as krill migrated toward the surface. We infer that the previously unstudied WAP embayments are important foraging areas for whales during autumn and, furthermore, that meso-scale variation in the distribution of whales and their prey are important features of this system. Recent decreases in the abundance of Antarctic krill around the WAP have been linked to reductions in sea ice, mediated by rapid climate change in this area. At the same time, baleen whale populations in the Southern Ocean, which feed primarily on krill, are recovering from past exploitation. Consideration of these features and the effects of climate change on krill dynamics are critical to managing both krill harvests and the recovery of baleen whales in the Southern Ocean
A Solve-RD ClinVar-based reanalysis of 1522 index cases from ERN-ITHACA reveals common pitfalls and misinterpretations in exome sequencing
Purpose
Within the Solve-RD project (https://solve-rd.eu/), the European Reference Network for Intellectual disability, TeleHealth, Autism and Congenital Anomalies aimed to investigate whether a reanalysis of exomes from unsolved cases based on ClinVar annotations could establish additional diagnoses. We present the results of the âClinVar low-hanging fruitâ reanalysis, reasons for the failure of previous analyses, and lessons learned.
Methods
Data from the first 3576 exomes (1522 probands and 2054 relatives) collected from European Reference Network for Intellectual disability, TeleHealth, Autism and Congenital Anomalies was reanalyzed by the Solve-RD consortium by evaluating for the presence of single-nucleotide variant, and small insertions and deletions already reported as (likely) pathogenic in ClinVar. Variants were filtered according to frequency, genotype, and mode of inheritance and reinterpreted.
Results
We identified causal variants in 59 cases (3.9%), 50 of them also raised by other approaches and 9 leading to new diagnoses, highlighting interpretation challenges: variants in genes not known to be involved in human disease at the time of the first analysis, misleading genotypes, or variants undetected by local pipelines (variants in off-target regions, low quality filters, low allelic balance, or high frequency).
Conclusion
The âClinVar low-hanging fruitâ analysis represents an effective, fast, and easy approach to recover causal variants from exome sequencing data, herewith contributing to the reduction of the diagnostic deadlock
Observational carbon and nitrogen zooplankton stable isotope and environmental data in the North Atlantic Ocean from 2009-2018
Calanus (copepod) sampled by the Continuous Plankton Recorder (CPR) survey (https://www.cprsurvey.org/) in the North Atlantic from 2009-2018 were analysed for stable carbon (d13C) and nitrogen (d15N) isotopes. This observational dataset was used together with environmental variables (sea surface temperature, mixed layer depth, chlorophyll a, wind speed) to develop Bayesian spatial models and to produce yearly and seasonal isoscapes (spatial modelling of stable isotope ratio) for 1998-2020
Modelled carbon and nitrogen zooplankton stable isotope data in the North Atlantic Ocean from 1998-2020
Calanus (copepod) sampled by the Continuous Plankton Recorder (CPR) survey (https://www.cprsurvey.org/) in the North Atlantic from 2009-2018 were analysed for stable carbon (d13C) and nitrogen (d15N) isotopes. This observational dataset was used together with environmental variables (sea surface temperature, mixed layer depth, chlorophyll a, wind speed) to develop Bayesian spatial models and to produce yearly and seasonal isoscapes (spatial modelling of stable isotope ratio) for 1998-2020. This dataset contains the isoscapes data, the isoscapes plots and and the Suess correction factors for the d13C isoscape data
Distribution et structure des communautés zooplanctoniques dans deux écosystÚmes cÎtiers. : Analyse de l'impact des facteurs physiques et trophiques sur les distributions spatiales et les spectres de taille du zooplancton.
La structure de taille et la distribution spatiale du zooplancton ont Ă©tĂ© Ă©tudiĂ©es dans deux Ă©cosystĂšmes : une baie de la cĂŽte Ouest de la pĂ©ninsule antarctique et le golfe du Lion en mer mĂ©diterranĂ©e occidentale. L'acquisition des spectres a Ă©tĂ© permise par l'utilisation de deux capteurs optiques : le ZooScan / ZooProcess et le Laser Optical Plankton Counter (LOPC). L'impact de diffĂ©rents types de forçages sur les spectres de taille des communautĂ©s zooplanctoniques a Ă©tĂ© mis en Ă©vidence dans les deux Ă©cosystĂšmes cĂŽtiers, notamment grĂące aux caractĂ©ristiques des spectres de biomasse normalisĂ©e. Le long de la pĂ©ninsule Antarctique, la fin de l'automne est une pĂ©riode charniĂšre Ă tous les niveaux trophiques avec la baisse de la production primaire et l'agrĂ©gation du krill (Euphausia superba) dans les baies continentales. Les donnĂ©es ADCP ont permis de localiser dans une des baies le plus grand banc de krill Ă©chantillonnĂ© depuis 20 ans. L'Ă©tude du comportement alimentaire du krill en rĂ©ponse Ă la baisse de la production primaire a montrĂ© l'impact du krill sur les spectres de taille des communautĂ©s mĂ©sozooplanctoniques, et en particulier sur les espĂšces de petites tailles. Un autre type de forçage a Ă©tĂ© mis en avant dans le golfe du Lion, oĂč les structures physiques trĂšs variables induites par les apports du RhĂŽne, le courant Liguro-Provençal et les vents influent directement sur la distribution spatiale du zooplancton. Des sous-rĂ©gions ont Ă©tĂ© identifiĂ©es Ă partir de corrĂ©lations entre des paramĂštres physiques tels que la stratification de la colonne d'eau et des paramĂštres biologiques tels que la concentration en chl-a ou la pente des spectres de biomasse normalisĂ©e.Zooplankton size structure and spatial distribution were investigated in a bay along the West Antarctic Peninsula (WAP) and in the Gulf of Lion in Western Mediterranean Sea. Zooplankton size spectra were determined with the use of two optical sensors, the Laser Optical Plankton Counter (LOPC) and the ZooScan / ZooProcess system. Using features of the biomass size spectrum is was possible to identify different forcing processes that affected zooplankton size spectrum and spatial distribution in the two ecosystems. In WAP, late fall is a transition time at all the trophic levels, with the decrease of primary production and the aggregation of Antarctic krill (Euphausia Superba) in continental bays. ADCP data permitted to find in a bay the largest Antarctic krill swarm reported in the last twenty years. Study of krill feeding behavior in response to the decrease of primary production showed impact of krill on mesozooplankton size spectrum and especially a decrease of the small size species abundance. A different type of forcing was found in the Gulf of Lion, where zooplankton spatial distribution was affected by physical structures such as the inputs by the RhĂŽne river, the Liguro-Provençal current and winds. The correlation between physical and biological parameters e.g. water masses stratification, chl-a concentration, slope of the normalized biomass size spectrum (NBSS), allowed the identification of three different regions in the Gulf of Lion. These potential habitats show different zooplankton size structure, with strong NBSS slopes close to the coast and weaker NBSS slopes in the zone of the RhĂŽne plume influence
Environmental effects on zooplankton abundance on a sub-Arctic shelf off northern Norway
publishedVersio
Relationship between zooplankton distribution and physicals structures during two different seasons in the Gulf of Lion.
International audienceDuring three cruises (2 to 17 October 2009, 26 April to 7 May 2010, 23 January to 4 February 2011), the whole French continental shelf of the Gulf of Lion was sampled to obtain an overview on the zooplankton community size structure. 6 transects from the coast to the open ocean were conducted for a total of 160 stations. A laser optical plankton counter (LOPC) was used to estimate abundance, biovolume, and general characteristics of size spectra. The vertical distribution of, the LOPC counts, the chla concentration and the hydrological parameters was investigated in order to highlight their interactions and the main structures. Different patterns of particle distributions occur following the water column structure and the bathymetry. A PCA was done on physicals and biological parameters to interpret the links between the different parameters. A clustering test allowed us to define 3 spatial areas corresponding potentially to different type of habitat: the RhÎne plume, the coastal area and the continental shelf area. The zooplankton size distribution was investigated within the three areas using the normalized biomass size spectrum (NBSS). The coastal area was characterized by the highest NBSS slopes and highest chla concentration, the upwelling and the formation of deep water participated to keep the water mixed. The RhÎne plume showed the lowest NBSS slopes associated with strong water stratification. These waters were rich in nutrient promoted high chlorophyll a concentrations in the surface water layer and carried on the continental shelf a lot of organic matter. The continental shelf showed the lowest abundances and was hit by the Liguro-Provençal current depending on the season. The NBSS slopes were higher during winter, meaning the proportions of large organisms were more important during the post bloom period (May and October)
Variable predatorâprey relations in zooplankton overwintering in subarctic fjords
Zooplankton predatorâprey relations in northern Norwegian fjords are highly variable in time and space, and the mechanisms driving this variability are still poorly understood. Replicate Juday net sampling in October and February from 1983 to 2005, which included five repeated tows from bottom to surface, was conducted in Saltfjord and Mistfjord, northern Norway. The time-series provided evidence of in situ variability in species abundance, as well as seasonal and interannual changes in standing stock abundance. The shallow sill of one fjord caused accumulation of coastal water in the fjordâs basin, while the other fjordâs deeper sill selected denser water of Atlantic origin from the same open shelf habitat. The selective advection caused differences in the immigration of species recruiting to the fjordsâ specific overwintering communities of zooplankton. Statistical analyses of the cumulated replicate data indicated significant in situ variability in the spatial density of species. Cases with an abundance of carnivores relating positively to other species probably resulted from the carnivoresâ attraction to patches with concentrations of prey. Interspecific negative density relations likely indicated either predator avoidance or substantial trophic activity during the sampling. During years of high abundance, some wintering stocks of carnivores evidently reduced the local stocks of overwintering prey. We conclude that predatorâprey interactions and stock variability in Subarctic fjords result from complex bio-geophysical interactions that occur on the scales of local habitats and basin-scale population systems