Effects of petrogenic pollutants on North Atlantic and Arctic Calanus copepods: From molecular mechanisms to population impacts.

Oil and gas industries in the Northern Atlantic Ocean have gradually moved closer to the Arctic areas, a process expected to be further facilitated by sea ice withdrawal caused by global warming. Copepods of the genus Calanus hold a key position in these cold-water food webs, providing an important energetic link between primary production and higher trophic levels. Due to their ecological importance, there is a concern about how accidental oil spills and produced water discharges may impact cold-water copepods. In this review, we summarize the current knowledge of the toxicity of petroleum on North Atlantic and Arctic Calanus copepods. We also review how recent development of high-quality transcriptomes from RNA-sequencing of copepods have identified genes regulating key biological processes, like molting, diapause and reproduction in Calanus copepods, to suggest linkages between exposure, molecular mechanisms and effects on higher levels of biological organization. We found that the available ecotoxicity threshold data for these copepods provide valuable information about their sensitivity to acute petrogenic exposures; however, there is still insufficient knowledge regarding underlying mechanisms of toxicity and the potential for long-term implications of relevance for copepod ecology and phenology. Copepod transcriptomics has expanded our understanding of how key biological processes are regulated in cold-water copepods. These advances can improve our understanding of how pollutants affect biological processes, and thus provide the basis for new knowledge frameworks spanning the effect continuum from molecular initiating events to adverse effects of regulatory relevance. Such efforts, guided by concepts such as adverse outcome pathways (AOPs), enable standardized and transparent characterization and evaluation of knowledge and identifies research gaps and priorities. This review suggests enhancing mechanistic understanding of exposure-effect relationships to better understand and link biomarker responses to adverse effects to improve risk assessments assessing ecological effects of pollutant mixtures, like crude oil, in Arctic areas.

PAHs in high Arctic copepods Calanus hyperboreus following exposure of residues from in situ burning of oil spill.

In situ burning of marine oil spills reduces the total amount of oil in the environment, but a negative side effect may be the generation of environmentally hazardous polycyclic aromatic hydrocarbons (PAHs) that may pose a risk for bioaccumulation, particularly in organisms having a high lipid content. In this study uptake of PAHs from oil and burn residue were examined in the high arctic copepod Calanus hyperboreus. A major part of the low ring number petrogenic PAHs in the oil was removed during burning and relative higher concentrations of pyrogenic high ring number PAHs was found in the burn residue. This suggests that burning markedly reduces the general PAH exposure load. Furthermore, the pyrogenic PAHs generated during the burn were not bioconcentrated to quantifiable levels in the copepods. We conclude that in situ burning can mitigate the potential risk of PAH uptake for copepods and other pelagic organisms in the marine environment as the pyrogenic PAHs only pose low risk for uptake from the water by the copepods and other pelagic organisms.

Predation effect on copepods by the giant jellyfish Nemopilema nomurai during the early occurrence stage in May in the northern East China Sea and southern Yellow Sea, China.

Massive blooms of Nemopilema nomurai have occurred recently across East Asian waters. They are potentially important as zooplankton predators, as well as being competitors for prey with zooplanktivorous fish. Few studies have estimated the predation effects on zooplankton by N. nomurai in situ. To quantify the natural diets and feeding rates and estimate the predation effects, N. nomurai medusae were collected in the northern East China Sea and southern Yellow Sea, one of the principal nursery grounds of this jellyfish, during May 2019. The gut contents indicated that copepods were an important food source for N. nomurai; copepods <1000 µm represented the bulk of total prey intake in number (> 99 %). Linear regression analyses showed that the copepods number in the gut contents was significantly influenced by medusa diameter and prey abundance. Calculations using the above data indicated that one medusa (mean diameter: 26.06 ± 9.73 cm) consumed approximately 5248 ± 2768 of copepods daily. However, even the maximum predation pressure was <0.1 % of the total copepods standing stock daily due to the small diameter and low density/biomass of N. nomurai medusae in May 2019. The data presented here suggested that the predation effects of N. nomurai on copepods were low and might not reduce prey availability to fish with diets consisting mainly of copepods during the early occurrence stage of the N. nomurai population.

A Recombinant Genotype I Japanese Encephalitis Virus Expressing a Gaussia Luciferase Gene for Antiviral Drug Screening Assay and Neutralizing Antibodies Detection.

Japanese encephalitis virus (JEV) is the major cause of viral encephalitis in humans throughout Asia. In the past twenty years, the emergence of the genotype I (GI) JEV as the dominant genotype in Asian countries has raised a significant threat to public health security. However, no clinically approved drug is available for the specific treatment of JEV infection, and the commercial vaccines derived from the genotype III JEV strains merely provided partial protection against the GI JEV. Thus, an easy-to-perform platform in high-throughput is urgently needed for the antiviral drug screening and assessment of neutralizing antibodies specific against the GI JEV. In this study, we established a reverse genetics system for the GI JEV strain (YZ-1) using a homologous recombination strategy. Using this reverse genetic system, a gaussia luciferase (Gluc) expression cassette was inserted into the JEV genome to generate a reporter virus (rGI-Gluc). The reporter virus exhibited similar growth kinetics to the parental virus and remained genetically stable for at least ten passages in vitro. Of note, the bioluminescence signal strength of Gluc in the culture supernatants was well correlated with the viral progenies determined by viral titration. Taking advantage of this reporter virus, we established Gluc readout-based assays for antiviral drug screening and neutralizing antibody detection against the GI JEV. These Gluc readout-based assays exhibited comparable performance to the assays using an actual virus and are less time consuming and are applicable for a high-throughput format. Taken together, we generated a GI JEV reporter virus expressing a Gluc gene that could be a valuable tool for an antiviral drug screening assay and neutralization assay.

No Effect of Calanus Oil on Maximal Oxygen Uptake in Healthy Participants: A Randomized Controlled Study.

We aimed to investigate the long-term effect of daily Calanus oil supplementation on maximal oxygen uptake (VO2max) in healthy 30- to 50-year-old participants. The study was motivated by preclinical studies reporting increased VO2max and metabolic health with omega-3 rich Calanus oil. In a double-blinded study, 71 participants were randomized to receive 2 g/day of Calanus or placebo supplementation for a total of 6 months. The participants underwent exercise testing and clinical investigations at baseline, 3 months, and 6 months. Main study endpoint was change in VO2max from baseline to 6 months. Fifty-eight participants completed the 6-month test and were included in the final data analysis (age: Calanus, 39.7 [38.0, 41.4] and placebo, 38.8 [36.8, 40.9] years; body mass index: Calanus, 24.8 [24.0, 25.6] and placebo, 24.8 [23.7, 25.8] kg/m2; and VO2max: Calanus, 50.4 [47.1, 53.8] and placebo, 50.2 [47.2, 53.1] ml·kg-1·min-1). There were no between-group differences at baseline, nor were there any between-group differences in absolute (Calanus, 3.74 [3.44, 4.04] and placebo, 3.79 [3.44, 4.14] L/min) or relative VO2max (Calanus, 49.7 [46.2, 53.2] and placebo, 49.5 [46.0, 53.1] ml·kg-1·min-1) at 6 months (mean [95% confidence interval]). There were no between-groups change in clinical measures from baseline to 3 and 6 months. In conclusion, VO2max was unaffected by 6 months of daily Calanus oil supplementation in healthy, physically fit, normal to overweight men and women between 30 and 50 years old.

Surge in the jellyfish population of a tropical monsoonal estuary: A boon or bane to its plankton community dynamics?

Recurrent jellyfish blooms and their impacts on ecosystem deliverables of coastal habitats have become a major ecological concern. In view of this, repercussions of a surge in the jellyfish population on the plankton community were studied in Cochin estuary (CE), the largest tropical estuary along the southwest coast of India. Evaluation of hydrographic attributes and plankton community of the CE during early and late pre-monsoon revealed a marked disparity in its hydrography which favoured an increase in jellyfish abundances during late pre-monsoon, eliciting distinct impacts on the plankton community. The escalation in the jellyfish abundance and their subsequent predation on the crustacean plankton released the phytoplankton community from the grazing pressure resulting in a trophic cascade in the planktonic food web. The indiscriminate feeding of jellyfishes on the ichthyoplankton, decapod larvae, and Copepoda, the primary diet component of forage fishes evoked a potent threat to the fishery potential of CE.

Role of jellyfish in mesozooplankton community stability in a subtropical bay under the long-term impacts of temperature changes.

To understand zooplankton community changes in the context of climate change and anthropogenic disturbances, we analyzed mesozooplankton samples from four seasons in the subtropical Daya Bay, which is susceptible to perceived disturbances in the South China Sea. The zooplankton community was found to be divided into two clusters, namely the Outer-bay Cluster (OC) comprising Noctiluca scintillans, Temora turbinata, and Paracalanus spp., and the Inner-bay Cluster (IC) which was dominated by Pseudevadne tergestina, Oikopleura rufescens, and Paracalanus spp. The OC was recorded in waters with low Chl a concentrations and high salinity, coinciding with open seawater intrusion. The IC occurred in waters with high Chl a concentrations, low salinity, with terrestrial inputs from the Dan'ao River. The dominant cladoceran species has changed in spring from Penilia avirostris to Pseudevadne tergestina owing to suitable temperature conditions and the low wind speed in this region. Most of the keystone species recorded during all seasons were found to be copepods based on co-occurrence network analysis. Numbers of keystone jellyfish (cnidaria) species, such as Geryonia proboscidalis, Chelophyes contorta, and Aeginura grimaldi were significantly higher in summer than in other seasons due to a low-temperature seawater intrusion, which can result in the highest stability of community structures and affect coastal food webs and fishery resources. Our results highlight that zooplankton community succession may occur with long-term temperature changes in the subtropical Daya Bay under global climate change conditions.

Changes in Chemical Composition and Copepod Toxicity during Petroleum Photo-oxidation.

Photoproducts can be formed rapidly in the initial phase of a marine oil spill. However, their toxicity is not well understood. In this study, oil was irradiated, chemically characterized, and tested for toxicity in three copepod species (Acartia tonsa, Temora longicornis, and Calanus finmarchicus). Irradiation led to a depletion of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes in oil residues, along with an enrichment in aromatic and aliphatic oil photoproducts. Target lipid model-based calculations of PAH toxicity units predicted that PAH toxicities were lower in water-accommodated fractions (WAFs) of irradiated oil residues ("irradiated WAFs") than in WAFs of dark-control samples ("dark WAFs"). In contrast, biomimetic extraction (BE) measurements showed increased bioaccumulation potential of dissolved constituents of irradiated WAFs compared to dark WAFs, mainly driven by photoproducts present in irradiated oil. In line with the BE results, copepod mortality increased in irradiated WAFs compared to dark WAFs. However, low copepod toxicities were observed for WAFs produced with photo-oxidized oil slicks collected during the Deepwater Horizon oil spill. The results of this study suggest that while oil photoproducts have the potential to be a significant source of copepod toxicity, dilution and dispersion of these higher solubility products appear to help mitigate their toxicity at sea.

Application of chemical herders do not increase acute crude oil toxicity to cold-water marine species.

Chemical herders may be used to sequester and thicken surface oil slicks to increase the time window for performing in situ burning of spilled oil on the sea surface. For herder use to be an environmentally safe oil spill response option, information regarding their potential ecotoxicity both alone and in combination with oil is needed. This study aimed at assessing if using herders can cause toxicity to cold-water marine organisms. Our objective was to test the two chemical herders Siltech OP-40 (OP-40) and ThickSlick-6535 (TS-6535) with and without oil for toxicity using sensitive life stages of cold-water marine copepod (Calanus finmarchicus) and fish (Gadus morhua). For herders alone, OP-40 was consistently more toxic than TS-6535. To test herders in combination with oil, low-energy water accommodated fractions (LE-WAFs, without vortex) with Alaskan North Slope crude oils were prepared with and without herders. Dissolution of oil components from surface oil was somewhat delayed following herder application, due to herder-induced reduction in contact area between water and oil. The LE-WAFs were also used for toxicity testing, and we observed no significant differences in toxicity thresholds between treatments to LE-WAFs generated with oil alone and oil treated with herders. The operational herder-to-oil ratio is very low (1:500), and the herders tested in the present work displayed acute toxicity at concentrations well above what would be expected following in situ application. Application of chemical herders to oil slicks is not expected to add significant effects to that of the oil for cold-water marine species exposed to herder-treated oil slicks.

Marine Oil from C. finmarchicus Enhances Glucose Homeostasis and Liver Insulin Resistance in Obese Prediabetic Individuals.

The intermediate state between normal glucose tolerance and overt type 2 diabetes mellitus is associated with micro- and macrovascular diseases, requiring safe and cost-effective treatment measures interventions. A novel source of LC n-3 FAs is Calanus finmarchicus Oil, which showed promising effects on glucose homeostasis in preclinical studies due to anti-obesity effects and/or anti-inflammatory properties. In total, 43 obese patients (BMI: 31.7 ± 5.2 kg/m2) were allocated in the following two groups: (1) Calanus oil group (2 g CO/day) and (2) placebo group (2 g paraffin oil/day). Markers of glucose metabolism, body composition and energy intake were measured at the beginning (t0), after 12 weeks (t12) and 16 weeks (t16). Overall, parameters reflecting abnormal glucose homeostasis and insulin resistance in the liver, including fasting insulin (-2.9 mU/L ± 4.10, p < 0.05), HOMA-IR (-0.9 ± 1.28, p < 0.05) and hepatic insulin resistance index (-1.06 ± 1.72 × 106, p < 0.05) significantly enhanced after a 12-week CO-intervention, while no differences were observed in HbA1c, AUC0-2h Glucose, AUC0-2h Insulin, 2 h plasma glucose and muscle insulin sensitivity index. Our results indicate that Calanus oil causes beneficial effects on glucose metabolism and insulin resistance in obese patients, with clinical relevance to be verified in further studies. In addition, the possible active compounds and their mechanisms of action should be elucidated.

Oil-mediated oxidative-stress responses in a keystone zooplanktonic species, Calanus finmarchicus.

The copepod Calanus finmarchicus is an ecologically important species in the North Atlantic, Norwegian and Barents seas. Accidental or continuous petroleum pollution from oil and gas production in these seas may pose a significant threat to this low trophic level keystone species. Responses related to oxidative stress, protein damage and lipid peroxidation were investigated in C. finmarchicus exposed to a water-accommodated fraction (WAF) of a naphthenic North Atlantic crude oil. The exposure concentration corresponded to 50% of the 96 h LC50, and samples were obtained at 0, 24, 48, 72 and 96 h after exposure initiation. Gene expressions (superoxide dismutase, catalase, glutathione S-transferase, glutathione synthetase, heat shock protein 70 and 90, ubiquitin and cytochrome P-450 330A1), enzyme activities (superoxide dismutase, catalase, glutathione S-transferase) and concentrations of total glutathione and malondialdehyde were analyzed. Gene expression analyses showed no differences between controls and the exposed animals, however significantly higher glutathione S-transferase activity and malondialdehyde concentrations were found in the exposed group, suggests lipid peroxidation as main toxic effect.

Identification and characterization of homeobox gene clusters in harpacticoid and calanoid copepods.

In this study, we have identified the entire complement of typical homeobox (Hox) genes (Lab, Pb, Dfd, Scr, Antp, Ubx, Abd-A, and Abd-B) in harpacticoid and calanoid copepods and compared them with the cyclopoid copepod Paracyclopina nana. The harpacticoid copepods Tigriopus japonicus and Tigriopus kingsejongensis have seven Hox genes (Lab, Dfd, Scr, Antp, Ubx, Abd-A, and Abd-B) and the Pb and Ftz genes are also present in the cyclopoid copepod P. nana. In the Hox gene cluster of the calanoid copepod Eurytemora affinis, all the Hox genes were present linearly in the genome but the Antp gene was duplicated. Of the three representative copepods, the P. nana Hox gene cluster was the most compact due to its small genome size. The Hox gene expression profile patterns in the three representative copepods were stage-specific. The Lab, Dfd, Scr, Pb, Ftz, and Hox3 genes showed a high expression in early developmental stages but Antp, Ubx, Abd-A, and Abd-B genes were mostly expressed in later developmental stages, implying that these Hox genes may be closely associated with the development of segment identity during early development.

Levels of hydrocarbons and toxicity of water-soluble fractions of maritime fuels on neotropical invertebrates.

Accidents involving fuels and oil spills are among the main sources of hydrocarbons to the marine ecosystems and often damage the biota. Diesel and bunker oil are two examples of fuels with broad application that release hydrocarbons to the aquatic environment and little is known about their toxicity on tropical organisms. This study aimed to assess the toxicity of the water-soluble fraction (WSF) of diesel and bunker oils to neotropical marine invertebrates. Commercial fuels were purchased for WSF extraction, analyzed for total petroleum hydrocarbons (TPH), and polycyclic aromatic hydrocarbons (PAHs), and acute and chronic toxicity determined. The WSF analyzed contained varied levels of TPH and PAHs mixtures, especially low molecular weight PAHs; bunker WSF presented higher amounts of TPH and PAHs. Both WSFs tested produced significant mortality of the brine shrimp Artemia salina, affected the reproduction rate of the copepod Nitokra sp, and impaired the embryo-larval development of the mussel Perna perna and of the sea urchin Lytechinus variegatus. In general WSF from diesel was more toxic to the organisms tested, but bunker WSF was more toxic to embryos of L. variegatus. Toxicity started from concentrations of 3% WSF, which can be environmentally relevant after an oil spill, indicating that marine biota may be adversely affected in short term.

Application of a biological multilevel response approach in the copepod Acartia tonsa for toxicity testing of three oil Water Accommodated Fractions.

Copepods play a critical role in the marine food webs, being a food source for marine organisms. In this study, we investigated the toxic effects of Water Accommodated Fractions (WAFs) from three types of oil: Naphthenic North Sea crude oil (NNS), Intermediate Fuel Oil (IFO 180) and a commercial Marine Gas Oil (MGO). The WAFs were prepared at 10 °C and 30 PSU (practical salinity unit), and tested on the marine copepod Acartia tonsa at different endpoints and at different levels of biological organization. We determined the median lethal concentrations after 96 h (LC50) and reproduction capabilities were calculated in adult females following seven days of exposure to sublethal WAF doses. The total lipid content was measured in reproductive females using Nile red lipophilic dye after 96 h of WAF exposure. We also measured the transcription levels of genes involved in antioxidant response and xenobiotic biotransformation after short exposure for 48 h. High doses (7% WAF) of MGO affected survival, percentage of fecund females, egg hatching success, and total lipid content. The IFO 180 WAF affected, at medium (20%) and high (40%) doses, the number of fecund females, mortality and produced significant effects on gene expression levels. In conclusion, toxicity assays showed that the WAFs prepared from refined oils were more toxic than crude oil WAF to Acartia tonsa.

A Comparison of Short-Term and Continuous Exposures in Toxicity Tests of Produced Waters, Condensate, and Crude Oil to Marine Invertebrates and Fish.

Petroleum hydrocarbons can be discharged into the marine environment during offshore oil and gas production or as a result of oil spills, with potential impacts on marine organisms. Ecotoxicological assay durations (typically 24-96 h) used to characterize risks to exposed organisms may not always reflect realistic environmental exposure durations in a high-energy offshore environment where hydrocarbons are mixed and diluted rapidly in the water column. To investigate this, we adapted 3 sensitive toxicity tests to incorporate a short-term pulse exposure to 3 petroleum-based products: a produced water, the water-accommodated fraction (WAF) of a condensate, and a crude oil WAF. We measured 48-h mobility of the copepod Acartia sinjiensis, 72-h larval development of the sea urchin Heliocidaris tuberculata, and 48-h embryo survival and deformities of yellowtail kingfish Seriola lalandi, after exposure to a dilution series of each of the 3 products for 2, 4 to 12, and 24 h and for the standard duration of each toxicity test (continuous exposure). Effects on copepod survival and sea urchin larval development were significantly reduced in short-term exposures to produced water and WAFs compared to continuous exposures. Fish embryos, however, showed an increased frequency of deformities at elevated concentrations regardless of exposure duration, although there was a trend toward increased severity of deformities with continuous exposure. The results demonstrate how exposure duration alters toxic response and how incorporating relevant exposure duration to contaminants into toxicity testing may aid interpretation of more realistic effects (and hence an additional line of evidence in risk assessment) in the receiving environment. Environ Toxicol Chem 2021;40:2587-2600. © 2021 CSIRO. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Responses to Mineral Supplementation and Salmon Lice (Lepeophtheirus salmonis) Infestation in Skin Layers of Atlantic Salmon (Salmo salar L.).

The crustacean ectoparasite salmon louse (Lepeophtheirus salmonis), which severely affects Atlantic salmon health and welfare is one of the main problems of commercial aquaculture. In the present study, fish were fed a diet supplemented with extra minerals through the inclusion of a commercial additive (Biofeed Forte Salmon), substituting wheat in the control diet, before experimental infestation with salmon lice. Lice counts reduced with time but with no apparent effect of the diets. Further, fish fed the mineral diet had an overall higher number of blue (acidic) mucous cells, while the ratio of purple mucous cells was higher in the mineral diet. The transcriptional response in skin was enhanced at 7 dpc (copepodite life stage) in fish fed the mineral diet including immune and stress responses, while at 21 dpc (pre-adult life stage), the difference disappeared, or reversed with stronger induction in the control diet. Overall, 9.3% of the genes affected with lice also responded to the feed, with marked differences in outer (scale + epidermis) and inner (dermis) skin layers. A comparison of transcriptome data with five datasets from previous trials revealed common features and gene markers of responses to lice, stress, and mechanically induced wounds. Results suggested a prevalence of generic responses in wounded skin and lice-infected salmon.

Severe Toxic Effects on Pelagic Copepods from Maritime Exhaust Gas Scrubber Effluents.

To reduce sulfur emission from global shipping, exhaust gas cleaning systems are increasingly being installed on board commercial ships. These so-called scrubbers extract SOX by spraying water into the exhaust gas. An effluent is created which is either released directly to the sea (open-loop system) or treated to remove harmful substances before release (closed-loop system). We found severe toxic effects in the ubiquitous planktonic copepod Calanus helgolandicus of exposure to effluents from two closed-loop systems and one open-loop system on North Sea ships. The effluents contained high concentrations of heavy metals and polycyclic aromatic hydrocarbons (PAHs), including alkylated PAHs. We observed significantly elevated mortality rates and impaired molting already in the lowest tested concentrations of each effluent: 0.04 and 0.1% closed-loop effluents and 1% open-loop effluent. These concentrations correspond to total hydrocarbon concentrations of 2.8, 2.0, and 3.8 µg L-1, respectively, and compared to previous studies on oil toxicity in copepods, scrubber effluents appear more toxic than, for example, crude oil. None of the individual PAHs or heavy metals analyzed in the effluents occurred in concentrations which could explain the high toxicity. The effluents showed unexpected alkylated PAH profiles, and we hypothesize that scrubbers act as witch's cauldrons where undesired toxic compounds form so that the high toxicity stems from compounds we know very little about.

Transcriptome Analysis of Atlantic Salmon (Salmo salar) Skin in Response to Sea Lice and Infectious Salmon Anemia Virus Co-Infection Under Different Experimental Functional Diets.

Sea lice (Lepeophtheirus salmonis) are ectoparasitic copepods that cause significant economic loss in marine salmoniculture. In commercial salmon farms, infestation with sea lice can enhance susceptibility to other significant pathogens, such as the highly contagious infectious salmon anemia virus (ISAv). In this study, transcriptomic analysis was used to evaluate the impact of four experimental functional feeds (i.e. 0.3% EPA/DHA+high-ω6, 0.3% EPA/DHA+high-ω6+immunostimulant (IS), 1% EPA/DHA+high-ω6, and 1% EPA/DHA+high-ω3) on Atlantic salmon (Salmo salar) during a single infection with sea lice (L. salmonis) and a co-infection with sea lice and ISAv. The overall objectives were to compare the transcriptomic profiles of skin between lice infection alone with co-infection groups and assess differences in gene expression response among animals with different experimental diets. Atlantic salmon smolts were challenged with L. salmonis following a 28-day feeding trial. Fish were then challenged with ISAv at 18 days post-sea lice infection (dpi), and maintained on individual diets, to establish a co-infection model. Skin tissues sampled at 33 dpi were subjected to RNA-seq analysis. The co-infection's overall survival rates were between 37%-50%, while no mortality was observed in the single infection with lice. With regard to the infection status, 756 and 1303 consensus differentially expressed genes (DEGs) among the four diets were identified in "lice infection vs. pre-infection" and "co-infection vs. pre-infection" groups, respectively, that were shared between the four experimental diets. The co-infection groups (co-infection vs. pre-infection) included up-regulated genes associated with glycolysis, the interferon pathway, complement cascade activity, and heat shock protein family, while the down-regulated genes were related to antigen presentation and processing, T-cell activation, collagen formation, and extracellular matrix. Pathway enrichment analysis conducted between infected groups (lice infection vs. co-infection) resulted in several immune-related significant GO terms and pathways unique to this group, such as "autophagosome", "cytosolic DNA-sensing pathway" and "response to type I interferons". Understanding how experimental functional feeds can impact the host response and the trajectory of co-infections will be an essential step in identifying efficacious intervention strategies that account for the complexities of disease in open cage culture.

Intake of Calanus finmarchicus oil for 12 weeks improves omega-3 index in healthy older subjects engaging in an exercise programme.

The n-3 PUFA, EPA and DHA, play an important role in human health. As the intake of EPA and DHA from the diet is often inadequate, supplementation of those fatty acids is recommended. A novel source of n-3 PUFA is Calanus finmarchicus oil (CO) which contains fatty acids mainly bound in wax esters. To date, no data are available on the effects of long-term intake of this marine oil on n-3 PUFA blood levels. Therefore, the aim of this study was to evaluate the effect of CO on the n-3 PUFA blood levels using the omega-3 index (O3I). The data originate from a larger randomised controlled trial. For this analysis, samples from seventy-two participants (59·2 (sd 6·2) years, BMI 27·7 (sd 5·28) kg/m2) were analysed. Of those, thirty-six performed 2×/week exercise and received 2 g of CO, which provided 124 mg stearidonic acid (SDA), 109 mg EPA and 87 mg DHA daily (EXCO group), while the other group performed exercise only (EX group) and served as a control for this analysis. The O3I increased from 6·07 (sd 1·29) % at baseline to 7·37 (sd 1·10) % after 12 weeks within the EXCO group (P < 0·001), while there were no significant changes in the EX group (6·01 (sd 1·26)-6·15 (sd 1·32) %, P = 0·238). These data provide first evidence that wax ester-bound n-3 PUFA from CO can significantly increase the O3I despite relatively low EPA + DHA amounts. Further, the effects of exercise could be excluded.

Microplastics do not increase bioaccumulation of petroleum hydrocarbons in Arctic zooplankton but trigger feeding suppression under co-exposure conditions.

Arctic sea ice has alarmingly high concentrations of microplastics (MPs). Additionally, sea ice reduction in the Arctic is opening new opportunities for the oil and maritime industries, which could increase oil pollution in the region. Yet knowledge of the effects of co-exposure to MPs and crude oil on Arctic zooplankton is lacking. We tested the influence of MPs (polyethylene, 20.7 µm) on polycyclic aromatic hydrocarbon (PAH) bioaccumulation and oil toxicity in the key arctic copepod Calanus hyperboreus after exposure to oil with and without dispersant. Up to 30% of the copepods stopped feeding and fecal pellet production rates were reduced after co-exposure to oil (1 µL L-1) and MPs (20 MPs mL-1). The PAH body burden was ~3 times higher in feeding than in non-feeding copepods. Copepods ingested both MPs and crude oil droplets. MPs did not influence bioaccumulation of PAHs in copepods or their fecal pellets, but chemical dispersant increased bioaccumulation, especially of ≥4 ring-PAHs. Our results suggest that MPs do not act as vectors of PAHs in Arctic marine food webs after oil spills, but, at high concentrations (20 MPs mL-1), MPs can trigger behavioral stress responses (e.g., feeding suppression) to oil pollution in zooplankton.