scholarly journals The salmon louse genome may be much larger than sequencing suggests

2022 ◽  
Author(s):  
Grace Wyngaard ◽  
Rasmus Skern-Mauritzen ◽  
Ketil Malde ◽  
Rachel Prendergast ◽  
Stefano Peruzzi
Keyword(s):  
Genome Size ◽  
North Atlantic ◽  
Single Copy ◽  
Bay Of Fundy ◽  
Lepeophtheirus Salmonis ◽  
The North ◽  
Salmon Lice ◽  
The North Atlantic ◽  
Genome Assemblies ◽  
Chromosome Level

The genome size of organisms impacts their evolution and biology and is often assumed to be characteristic of a species. Here we present the first published estimates of genome size of the ecologically and economically important ectoparasite, Lepeophtheirus salmonis (Copepoda, Caligidae). Four independent L. salmonis genome assemblies of the North Atlantic subspecies Lepeophtheirus salmonis salmonis, including two chromosome level assemblies, yield assemblies ranging from 665 to 790 Mbps. These genome assemblies are congruent in their findings, and appear very complete with Benchmarking Universal Single-Copy Orthologs analyses finding over 92% of expected genes and transcriptome datasets routinely mapping over 90% of reads. However, two cytometric techniques, flow cytometry and Feulgen image analysis densitometry, yield measurements in the range of 1.3 to 1.6 Gb in the haploid genome. Interestingly, earlier cytometric measurements reported genome sizes of 939 and 567 Mbps in L. salmonis salmonis samples from Bay of Fundy and Norway, respectively. Available data thus suggest that the genome sizes of salmon lice are variable. Current understanding of eukaryotic genome dynamics suggests that the most likely explanation for such variability involves repetitive DNA, which for L. salmonis makes up approx. 60% of the genome assemblies.

scholarly journals Losing the ‘arms race’: multiresistant salmon lice are dispersed throughout the North Atlantic Ocean

2021 ◽  
Vol 8 (5) ◽  
pp. 210265
Author(s):  
Helene Børretzen Fjørtoft ◽  
Frank Nilsen ◽  
Francois Besnier ◽  
Anne Stene ◽  
Ann-Kristin Tveten ◽  
...  
Keyword(s):  
North Atlantic ◽  
Food Production ◽  
North Atlantic Ocean ◽  
Arms Race ◽  
The North ◽  
Salmon Lice ◽  
Aquaculture Industry ◽  
The North Atlantic ◽  
Intensive Aquaculture ◽  
European Side

Nothing lasts forever, including the effect of chemicals aimed to control pests in food production. As old pesticides have been compromised by emerging resistance, new ones have been introduced and turned the odds back in our favour. With time, however, some pests have developed multi-pesticide resistance, challenging our ability to control them. In salmonid aquaculture, the ectoparasitic salmon louse has developed resistance to most of the available delousing compounds. The discovery of genetic markers associated with resistance to organophosphates and pyrethroids made it possible for us to investigate simultaneous resistance to both compounds in approximately 2000 samples of salmon lice from throughout the North Atlantic in the years 2000–2016. We observed widespread and increasing multiresistance on the European side of the Atlantic, particularly in areas with intensive aquaculture. Multiresistant lice were also found on wild Atlantic salmon and sea trout, and also on farmed salmonid hosts in areas where delousing chemicals have not been used. In areas with intensive aquaculture, there are almost no lice left that are sensitive to both compounds. These results demonstrate the speed to which this parasite can develop widespread multiresistance, illustrating why the aquaculture industry has repeatedly lost the arms race with this highly problematic parasite.

scholarly journals North Atlantic right whale (Eubalaena glacialis) and its food: (I) a spatial climatology of Calanus biomass and potential foraging habitats in Canadian waters

2019 ◽  
Vol 41 (5) ◽  
pp. 667-685 ◽  
Author(s):  
S Plourde ◽  
C Lehoux ◽  
C L Johnson ◽  
G Perrin ◽  
V Lesage
Keyword(s):  
Climate Change ◽  
Water Column ◽  
North Atlantic ◽  
Eubalaena Glacialis ◽  
Bay Of Fundy ◽  
North Atlantic Right Whale ◽  
Main Prey ◽  
Right Whale ◽  
The North ◽  
The North Atlantic

Abstract This study aimed at identifying potentially suitable foraging habitats for the North Atlantic right whale (NARW; Eubalaena glacialis) in the Gulf of St Lawrence (GSL), on the Scotian Shelf (SS) and in the Bay of Fundy (BoF), Canada, based on the distribution densities of their main prey, Calanus copepod species. More than 4800 historical Calanus spp. water column integrated samples as well as 221 vertically stratified sampling stations were used to create a 3D (latitude, longitude and vertical) climatology of Calanus spp. biomass densities for spring and summer–fall when NARW are feeding in Canadian waters. We then combined this 3D preyscape with bio-energetic considerations to highlight potentially suitable NARW foraging habitats in the region. Our 3D climatological approach successfully identified the known feeding areas of Grand Manan (BoF) and Roseway Basin (western SS), confirming its validity. Expanding our analyses to the GSL and other parts of the SS, we identified in both regions areas previously unknown where Calanus spp. biomass densities exceeded minimum levels suitable for foraging NARW. Our results represent a key contribution to the identification of important foraging areas for NARW in Canadian waters, especially in the context of climate change and the documented shift in NARW distribution.

A Record of the Atlantic Menhaden (Brevoortia tyrannus) from Northumberland Strait

1971 ◽  
Vol 28 (3) ◽  
pp. 461-462
Author(s):  
W. H. Lear ◽  
J. H. C. Pippy
Keyword(s):  
Nova Scotia ◽  
North Atlantic ◽  
Atlantic Menhaden ◽  
Bay Of Fundy ◽  
Single Specimen ◽  
Brevoortia Tyrannus ◽  
The North ◽  
The North Atlantic

A single specimen of the Atlantic menhaden (Brevoortia tyrannus (Latrobe 1802)) was taken off South Kouchibouguac Bay in Northumberland Strait. Previous most northerly published records for the North Atlantic were from western Bay of Fundy and the most easterly record was from St. Mary's Bay, Nova Scotia.

Assessment of mitochondrial DNA structuring and nursery use in the North Atlantic right whale (Eubalaena glacialis)

1999 ◽  
Vol 77 (8) ◽  
pp. 1217-1222 ◽  
Author(s):  
S Malik ◽  
M W Brown ◽  
S D Kraus ◽  
A R Knowlton ◽  
P K Hamilton ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
North Atlantic ◽  
Nursery Area ◽  
Eubalaena Glacialis ◽  
Bay Of Fundy ◽  
Genetic Structuring ◽  
North Atlantic Right Whale ◽  
Right Whale ◽  
The North ◽  
The North Atlantic

The North Atlantic right whale (Eubalaena glacialis) inhabits five areas along the east coast of North America at different times of the year. During 17 years of field observations, it has been found that only 59% of the newborn calves are brought to the Bay of Fundy nursery area. To examine whether this is because of population structuring, the mitochondrial DNA (mtDNA) control region haplotypes were determined for 269 individuals. Seven polymorphic sites were found to define five haplotypes. Calves were divided into two groups based on whether or not they were brought to the Bay of Fundy nursery. Significant genetic structuring of mitochondrial haplotypes was found between these groups (p = 0.002). Mothers that have had more than three calves demonstrated significant fidelity (p = 0.005) to the Bay of Fundy, suggesting that philopatry is the basis for the genetic structuring. Although this study clearly identifies the existence of two subpopulations and an alternative nursery area(s), the location(s) of the alternative area(s) is unclear and remains an important issue for the conservation of the species.

Source of Paralytic Shellfish Toxin in the Bay of Fundy

1963 ◽  
Vol 20 (4) ◽  
pp. 983-996 ◽  
Author(s):  
A. Prakash
Keyword(s):  
North Atlantic ◽  
Primary Source ◽  
Bay Of Fundy ◽  
Marine Dinoflagellate ◽  
The North ◽  
Paralytic Shellfish Toxin ◽  
Paralytic Shellfish ◽  
Overwhelming Evidence ◽  
Shellfish Toxin ◽  
The North Atlantic

Seasonal rise in shellfish toxicity in the Bay of Fundy in 1961 was coincident with increased abundance of a marine dinoflagellate, Gonyaulax tamarensis, and the appearance of toxin in plankton extracts. Experiments with unialgal cultures of G. tamarensis isolated from the Bay of Fundy provided overwhelming evidence that it is the primary source of toxin in shellfish in this area and the Gulf of St. Lawrence. G. tamarensis is widely distributed in the North Atlantic and there is evidence of toxic and non-toxic strains of this species.

Population genetic differentiation of sea lice (Lepeophtheirus salmonis) parasitic on Atlantic and Pacific salmonids: analyses of microsatellite DNA variation among wild and farmed hosts

2004 ◽  
Vol 61 (7) ◽  
pp. 1176-1190 ◽  
Author(s):  
C D Todd ◽  
A M Walker ◽  
M G Ritchie ◽  
J A Graves ◽  
A F Walker
Keyword(s):  
Atlantic Salmon ◽  
North Atlantic ◽  
North Pacific ◽  
Lepeophtheirus Salmonis ◽  
Long Distance ◽  
Population Genetic Differentiation ◽  
The North ◽  
Wild Host ◽  
The North Atlantic ◽  
Farmed Atlantic Salmon

The copepod Lepeophtheirus salmonis is ectoparasitic on Atlantic and Pacific wild salmonids. It is a major pest to Atlantic salmon (Salmo salar) aquaculture and may be implicated in recent declines of certain European wild salmonid stocks. Variation at six microsatellite loci was assessed among L. salmonis from wild and farmed salmonids in Scotland, wild sea-run brown trout (Salmo trutta) in Norway, and farmed Atlantic salmon in eastern Canada. An outgroup North Pacific sample was obtained from farmed Atlantic salmon in British Columbia. No significant differentiation was found between L. salmonis from the host species or among samples from throughout the North Atlantic. This is consistent with long-distance oceanic migration of wild hosts and larval interchange between farmed and wild host stocks being sufficient to prevent genetic divergence of L. salmonis throughout the North Atlantic. These results have important management implications for both wild stock conservation and aquaculture in that genetically, L. salmonis in the North Atlantic comprises a single population: there is no evidence of isolation of populations on farmed hosts from those on wild fish. Comparison between North Pacific and North Atlantic L. salmonis populations showed significant but low differentiation (FST = 0.06).

The Currents of the North Atlantic

1892 ◽  
Vol 34 (872supp) ◽  
pp. 13940-13941
Author(s):  
Richard Beynon
Keyword(s):  
North Atlantic ◽  
The North ◽  
The North Atlantic

NATO adaptation to current challenges and mechanisms of Ukraine’s cooperation with the North Atlantic Treaty Organization

2019 ◽  
pp. 73-81
Author(s):  
Oleh Poshedin
Keyword(s):  
North Atlantic ◽  
Task Force ◽  
Response Force ◽  
Cyber Attack ◽  
Adaptation Measures ◽  
Joint Force ◽  
Security Environment ◽  
The North ◽  
The North Atlantic ◽  
Area Of Influence

The purpose of the article is to describe the changes NATO undergoing in response to the challenges of our time. Today NATO, as a key element of European and Euro-Atlantic security, is adapting to changes in the modern security environment by increasing its readiness and ability to respond to any threat. Adaptation measures include the components required to ensure that the Alliance can fully address the security challenges it might face. Responsiveness NATO Response Force enhanced by developing force packages that are able to move rapidly and respond to potential challenges and threats. As part of it, was established a Very High Readiness Joint Task Force, a new Allied joint force that deploy within a few days to respond to challenges that arise, particularly at the periphery of NATO’s territory. NATO emphasizes, that cyber defence is part of NATO’s core task of collective defence. A decision as to when a cyber attack would lead to the invocation of Article 5 would be taken by the North Atlantic Council on a case-by-case basis. Cooperation with NATO already contributes to the implementation of national security and defense in state policy. At the same time, taking into account that all decision-making in NATO based on consensus, Ukraine’s membership in the Alliance quite vague perspective. In such circumstances, in Ukraine you often can hear the idea of announcement of a neutral status. It is worth reminding that non-aligned status did not save Ukraine from Russian aggression. Neutral status will not accomplish it either. All talks about neutrality and the impossibility of Ukraine joining NATO are nothing but manipulations, as well as recognition of the Ukrainian territory as Russian Federation area of influence (this country seeks to sabotage the Euro-Atlantic movement of Ukraine). Think about it, Moldova’s Neutrality is enshrined in the country’s Constitution since 1994. However, this did not help Moldova to restore its territorial integrity and to force Russia to withdraw its troops and armaments from Transnistria.

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