Jarle Mork

Selection‐induced variation at the pantophysin locus (PanI) in a Norwegian fjord population of cod (Gadus morhua L.)

A total of 1290 cod (Gadus morhua L.), sampled between 1985 and 1999 from a spawning area in the Trondheimsfjord, Norway, were assayed for the nuclear‐encoded locus PanI (pantophysin). The majority of samples were taken during the spawning season at two nearby sampling locations at depths of 100 and 60 m, respectively. Genetic analysis revealed significant effects of cohort, sex and sampling location on allele frequencies at PanI. The contribution of each of these three factors to the total among‐sample diversity (FST) of 8.01% at PanI was estimated to be 3.78, 2.55 and 1.68%, respectively. Sign tests revealed a significant excess of heterozygotes at both sampling locations in females; a significant excess of heterozygotes in males was observed at one of the localities. Mutation, genetic drift and immigration do not appear to contribute significantly to the observed genetic heterogeneity at PanI, leaving natural selection as the main explanatory factor for the Hardy–Weinberg imbalance. The dynamics of the selection at PanI appear to be complex. Analysis of age, sex and cohort proved crucial to disentangle putative explanatory factors from their secondary effects.

Genetic structure of cod along the coast of Norway: Results from isozyme studies

Abstract A total of 521 cod in samples from eight coastal and fjord locations along the Norwegian coast, from the Russian border to mid-Norway, were assessed for allele frequencies at six polymorphic tissue enzyme loci (LDH-3*, PGM-1*, MDH-3*, IDHP-1*, PGI-1* and PGI-2*). According to individual otolith deposition patterns, the four northernmost samples contained both North-East Arctic (“arclie(”) cod and Norwegian coastal ((“coastal(”) cod. At five of the loci, cod appeared to be one genetically homogeneous unit thmughout the sampling area. Locus LDH-3*, however, showed substantial inter-sample genetic heterogeneity. At this locus, samples from northern Norway (north of the Lofoten Islands) had significantly lower frequencies of the LDH-3* 100 allele than those from mid-Norway, whereas the frequencies within each of these groups were not significantly heterogeneous. Among cod typed as “arctic”, however, there was a statistically significant surplus of LDH-3* heterozygotes on some locations and in some ag...

Venom on ice: First insights into Antarctic octopus venoms

The venom of Antarctic octopus remains completely unstudied. Here, a preliminary investigation was conducted into the properties of posterior salivary gland (PSG) extracts from four Antarctica eledonine (Incirrata; Octopodidae) species (Adelieledone polymorpha, Megaleledone setebos, Pareledone aequipapillae, and Pareledone turqueti) collected from the coast off George Vs Land, Antarctica. Specimens were assayed for alkaline phosphatase (ALP), acetylcholinesterase (AChE), proteolytic, phospholipase A(2) (PLA(2)), and haemolytic activities. For comparison, stomach tissue from Cirroctopus sp. (Cirrata; Cirroctopodidae) was also assayed for ALP, AChE, proteolytic and haemolytic activities. Dietary and morphological data were collected from the literature to explore the ecological importance of venom, taking an adaptive evolutionary approach. Of the incirrate species, three showed activities in all assays, while P. turqueti did not exhibit any haemolytic activity. There was evidence for cold-adaptation of ALP in all incirrates, while proteolytic activity in all except P. turqueti. Cirroctopus sp. stomach tissue extract showed ALP, AChE and some proteolytic activity. It was concluded that the AChE activity seen in the PSG extracts was possibly due to a release of household proteins, and not one of the secreted salivary toxins. Although venom undoubtedly plays an important part in prey capture and processing by Antarctica eledonines, no obvious adaptations to differences in diet or morphology were apparent from the enzymatic and haemolytic assays. However, several morphological features including enlarged PSG, small buccal mass, and small beak suggest such adaptations are present. Future studies should be conducted on several levels: Venomic, providing more detailed information on the venom compositions as well as the venom components themselves; ecological, for example application of serological or genetic methods in identifying stomach contents; and behavioural, including observations on capture of different types of prey.

Genetic differentiation between the New Zealand and Falkland Islands populations of southern blue whiting Micromesistius australis

Abstract The southern blue whiting Micromesistius australis (Norman, 1937) is found in two geographically distinct areas, the South Atlantic and south‐west Pacific Oceans. To date there has been no appraisal of the genetic relationships between the populations in these two areas. Here, we present analyses of New Zealand and Falkland southern blue whiting using mini‐ and microsatellite loci. Two out of six loci show highly significant allele frequency heterogeneities between the two areas, strongly suggesting genetically distinct populations.

VNTR variability in Atlantic poor cod (Trisopterus minutus minutus) throughout its range: single locus minisatellite data suggest reproductive isolation for the Faroe Bank population

Nine samples of Atlantic poor cod, Trisopterus minutus minutus, collected from the Bay of Biscay to Trondheimsfjord, Norway, were analysed using three minisatellite DNA loci, amplified using PCR and screened with an automated sequencer. One locus was found to be polymorphic. FST analysis using the polymorphic locus indicated that 2.2% of the total genetic diversity detected was due to differences among samples (FST=0.022; P<0.001). The only significant pair-wise heterogeneity was found between the Faroe Bank and each of the other samples. This is consistent with previous analyses of the same samples using 11 polymorphic allozyme loci.

Coming Soon to a Fjord Near You: Future Jellyfish Scenarios in a Changing Climate

ABSTRACT Over the last decades, a dense population of the deep-sea/oceanic scyphozoan jellyfish Periphylla periphylla has established itself as top predator in the Trondheimsfjord in Norway, which has caused the traditional fisheries in this fjord to suffer. This was, however, not the first fjord this jellyfish invaded, and data suggest that it will not be the last one, either. With warmer temperatures, the jellyfish is moving northward in Norway, but not all fjords are created equal, and it is not thriving or taking up residence just anywhere. The current article explores three fjords in which Periphylla periphylla has become the top predator and outcompeted former ones. The main question of interest is why the jellyfish becomes dominant in one fjord and not another. The next question is which other Norwegian fjords further north exist with similar characteristics where we therefore would expect Periphylla periphylla to proliferate in the future. The latter is important from a policy and adaptation perspective for the local community of people, since the proliferation of the species unmistakably leads to fewer fish for commercial harvest and potentially less attractive waters for tourism purposes. Results show that three northern fjords, the Skjerstadfjorden the Holandsfjorden, and Stordjupna in the Vestfjord appear to be particularly vulnerable to a future Periphylla periphylla invasion.

Haemoglobin genotypes in cod (Gadus morhua L): Their geographic distribution and physiological significance

Haemoglobin polymorphism in cod (Gadus morhua L) has been investigated throughout the last 50years. Field studies have shed light on the geographic distribution of the two common alleles (HbI(1) and HbI(2)), and laboratory studies have shown effects of genotype on physiological traits such as growth, reproduction and hypoxia tolerance. The geographic distribution of alleles shows a correlation with temperature, with increasing frequency of HbI(1) in warmer areas. This is likely due to temperature-related differences in oxygen affinity of the three genotypes. We provide a general ecological introduction to cod haemoglobin polymorphism and a detailed discussion of physiological studies, particularly laboratory growth studies. Although differences in oxygen uptake are almost certainly a contributory mechanism to observed differences in traits such as growth rate, many other environmental, behavioural and social factors may also contribute, making it difficult to quantify the effect of HbI either experimentally or in the field.

Precision-cut liver slices to investigate responsiveness of deep-sea fish to contaminants at high pressure

While deep-sea fish accumulate high levels of persistent organic pollutants (POPs), the toxicity associated with this contamination remains unknown. Indeed, the recurrent collection of moribund individuals precludes experimental studies to investigate POP effects in this fauna. We show that precision-cut liver slices (PCLS), an in vitro tool commonly used in human and rodent toxicology, can overcome such limitation. This technology was applied to individuals of the deep-sea grenadier Coryphaenoides rupestris directly upon retrieval from 530-m depth in Trondheimsfjord (Norway). PCLS remained viable and functional for 15 h when maintained in an appropriate culture media at 4 °C. This allowed experimental exposure of liver slices to the model POP 3-methylcholanthrene (3-MC; 25 μM) at levels of hydrostatic pressure mimicking shallow (0.1 megapascal or MPa) and deep-sea (5-15 MPa; representative of 500-1500 m depth) environments. As in shallow water fish, 3-MC induced the transcription of the detoxification enzyme cytochrome P4501A (CYP1A; a biomarker of exposure to POPs). This induction was diminished at elevated pressure, suggesting a limited responsiveness of C. rupestris toward POPs in its native environment. This very first in vitro toxicological investigation on a deep-sea fish opens the route for understanding pollutants effects in this highly exposed fauna.

Prevalence of the haemoflagellate Trypanosoma sp. in some common norwegian marine fish species

Abstract Protist parasites of the genus Trypanosoma were found in the blood of cod, Gadus morhua L., haddock, Melanogrammus aeglefinus (L.). poor cod, Trisopterus minutus (L.) and dab, Limanda limanda (L.) from coastal and fjord waters in mid-Norway during 1985–1987. Prevalence in cod was highest in the warmer part of the year. The species identity of the observed trypanosome is uncertain and the vector unknown. Characteristics of the present parasitism resemble those described for Trypanosoma murmanensis (NIKITIN) of Atlantic cod in Newfoundland and Murman waters. and for which the marine leech Johanssonia arctica (SELENSKV) is vector.

To adapt or not adapt: assessing the adaptive capacity of artisanal fishers in the Trondheimsfjord (Norway) to jellyfish (Periphylla periphylla) bloom and purse seiners

Abstract Worldwide increases of jellyfish has occurred during the last several decades. A dense population of a large scyphozoan jellyfish, Periphylla periphylla, has established itself as top predator in the Trondheimsfjord in Norway, impacting traditional fisheries. On this background we discuss the adaptive capacity of artisanal fishers and stakeholder involvement in environmental management. A serendipitous discovery was that fishers report that their capacity to adapt to the presence of jellyfish in fact was sufficient. What they could not adapt to, within the context of jellyfish proliferation, was top-down decisions from the national government allowing purse seiners into the fjord to harvest Sprat Sprattus sprattus and Atlantic Herring Clupea harengus rest quotas and thereby also large bycatches of the local codfishes. This harvest was perceived more detrimental to their fishery than was the jellyfish invasion. Relative to fisheries managements choice of regulatory mechanisms during times of climatic change, we argue that by involving stakeholders intimately, the resulting policy advice will be experienced bottom-up and, thus, more legitimate and serendipitous results of a critical nature are more likely to surface.