Aquaculture sludge as feed for black soldier fly: Transfer of chemical and biological contaminants and nutrients.

Aquaculture sludge (uneaten feed and faeces) is nutrient rich and has potential as feed for insects. The aim of this study was to investigate the transfer of chemical and biological contaminants, as well as nutrients, from aquaculture sludge to black soldier fly larvae. The larvae were reared on a sludge mixture made of different sludges collected from Norwegian freshwater salmonid facilities. The sludge was spiked with four common salmon pathogens: Infectious Pancreatic Necrosis Virus, Infectious Salmon Anemia virus, Yersinia ruckeri or Mycobacterium salmoniphilum. During the 15 days of growth on sludge, the black soldier fly larvae accumulated valuable nutrients including protein, fat, eicosapentaenoic acid, iron, manganese, zinc and selenium. The larvae also accumulated undesirable substances including cadmium, mercury, dioxins and polychlorinated biphenyls. The concentrations of dioxins exceeded the EU maximum level set for animal feed. None of the salmon pathogens that were spiked to the sludge were detected in the black soldier fly larvae. This study reports low risk of transfer of salmon pathogens from sludge to insect larvae, and showed that the transfer of heavy metals, minerals and metalloids are in accordance with earlier studies. The large variations in levels of heavy metals between batches of sludge can cause levels in BSF exceeding the EU maximum levels, and thus indicate a need for monitoring of the proposed value chain. The transfer of dioxins from sludge to insects, reported for the first time in this paper, would be of special interest for future research, with special focus on risk mitigation.

High resolution depth profile scanning of plankton organisms-VERTILICE.

Knowledge of the vertical migration pattern of sea lice (Lepeophtheirus salmonis) copepodites is necessary for designing efficient measures to prevent lice infestations on farmed Atlantic salmon (Salmo Salar) in sea-cages. However, data can be challenging to acquire at a large scale under realistic circumstances without interfering with the natural behavior of the specimen. A mesocosm platform was built to help acquire this data consisting of a sensor package in an underwater housing being pulled up and down along a 11-meter-long transparent tube containing planktonic organisms while collecting image-, temperature- and spectrometer data. The platform was placed at a salmon farm and the acrylic tube was filled with L. salmonis copepodites and was pre-programmed to run a profile scan twice per hour for four consecutive days. Using a fully convolutional neural network, the copepodites were automatically counted - creating a depth profile of detected lice and measured light specter. The final results showed a diurnal migration pattern throughout the test period.•Capable of acquiring vertical density profiles of any aquatic species between 0,5 - 10 mm down to 11 m below the surface.•Fully automated and can be left unintended for weeks while collecting data.

Characterization of nutrients and contaminants in fish sludge from Atlantic salmon (Salmo salar L.) production sites - A future resource.

A total of 47 fish sludge samples from commercial land-based Atlantic salmon (Salmo salar) farms in Norway were assessed for their nutrient composition, presence of various legacy contaminants and a wide spectrum of contaminants of emerging concern, veterinary medicines as well as selected salmonid pathogenic bacteria and virus. The aim was to document the levels of desirable and undesirable components in fish sludge in relation to a potential future use of sludge as invertebrate feed. The samples had variable, but relatively high protein and fat contents, indicating a high load of undigested feed in some of the sludge samples. Fatty acid analysis showed the presence of essential omega-3 fatty acids. In terms of undesirable substances, 43% and 84% of the sludge samples contained levels of arsenic and cadmium, respectively, which exceeded the EU Maximum Levels established for complete animal feed. The concentrations of copper, zinc, iron and aluminum were highly variable in the sludge samples. The concentrations of dioxins, sum PCB6, and chlorinated pesticides were all below the Maximum Levels for animal feed. Of the 18 per- and polyfluoroalkyl substances (PFAS) only one compound (L-PFOS) was present at measurable levels. None of the samples had detectable levels of veterinary medicines, salmonid virus or bacteria. Performing a suspect and non-target screening of the sludge samples identified 18 compounds, including four pharmaceuticals, plastic-related products and the UV filter benzophenone, warranting further investigations. Overall, the results from this study show that fish sludge is a nutrient-rich resource; however, undesirable substances, originating from the feed or from treatment of sludge may be present.

A whole-body transcriptome assembly of the annelid worm Hediste diversicolor.

The Annelida phylum is composed of a myriad of species exhibiting key phenotypic adaptations. They occupy key ecological niches in a variety of marine, freshwater and terrestrial ecosystems. Importantly, the increment of omic resources is rapidly modifying the taxonomic landscape and knowledge of species belonging to this phylum. Here, we comprehensively characterised and annotated a transcriptome of the common ragworm, Hediste diversicolor (OF Müller). This species belongs to the family Nereididae and inhabits estuarine and lagoon areas on the Atlantic coasts of Europe and North America. Ecologically, H. diversicolor plays an important role in benthic food webs. Given its commercial value, H. diversicolor is a promising candidate for aquaculture development and production in farming facilities, under a circular economy framework. We used Illumina next-generation sequencing technology, to produce a total of 105 million (M) paired-end (PE) raw reads and generate the first whole-body transcriptome assembly of H. diversicolor species. This high-quality transcriptome contains 69,335 transcripts with an N50 transcript length of 2313 bp and achieved a BUSCO gene completeness of 97.7% and 96% in Eukaryota and Metazoa lineage-specific profile libraries. Our findings offer a valuable resource for multiple biological applications using this species.

Complete mitochondrial genome of the ragworm annelid Hediste diversicolor (of Müller, 1776) (Annelida: Nereididae).

Marine annelids are a globally distributed and species-rich group, performing important ecological roles in macrobenthic communities. Yet, the availability of molecular resources to study these organisms is scarcer, comparatively with other phyla. Here, we present the first complete mitogenome of the Atlantic ragworm Hediste diversicolor (OF Muller, 1776). The mitogenome (15,904 bp long) contains 13 protein-coding genes, 22 transfer RNA, and two ribosomal RNA genes, all encoded in the same strand. Gene arrangement and composition are identical to those observed in two available congeneric species, Hediste diadroma and Hediste japonica. The phylogenetic analysis using both maximum-likelihood and Bayesian inference methods reveal a well-supported monophyly of genus Hediste and the already reported paraphyletic relationships within the subfamilies Nereidinae and Gymnonereidinae. Our results highlight the relevance of increasing the molecular sampling within this diverse group of marine fauna.

A machine vision system for tracking population behavior of zooplankton in small-scale experiments: a case study on salmon lice (Lepeophtheirus salmonis Krøyer, 1838) copepodite population responses to different light stimuli.

To achieve efficient and preventive measures against salmon lice (Lepeophtheirus salmonis Krøyer, 1838) infestation, a better understanding of behavioral patterns of the planktonic life stages is key. To investigate light responses in L. salmonis copepodites, a non-intrusive experimental system was designed to measure behavioral responses in a 12.5-l volume using machine vision technology and methodology. The experimental system successfully tracked the collective movement patterns of the sea lice population during exposure to different light stimuli emitted from alternating zones in the system. This system could further be used to study behavioral responses to different physical cues of various developmental stages of sea lice or other zooplankton.

Acute and sub-lethal effects of an anionic polyacrylamide on sensitive early life stages of Atlantic cod (Gadus morhua).

Despite the possible increase in use of anionic polyacrylamide (APAM) in enhanced oil recovery operations, very little relevant information regarding ecotoxicity exists. The current study assessed acute and sub-lethal toxicity in sensitive early life stages (ELS) of Atlantic cod (Gadus morhua) exposed to 200 kDa APAM under controlled laboratory conditions. Two experiments (screening and long-term study) were conducted covering ecologically relevant endpoints (survival, hatching, growth, deformations, respiration and heart rate) in fish developing through embryogenesis, hatching, yolk-sac larvae stage and the first feeding period. The screening experiment was an 8-day exposure of embryos, whereas in the long-term experiments embryos and developing larvae were exposed continuously for 23 days. In the screening experiment, a significant reduction in embryonic heart rate was observed during exposure to 150 and 1500 mg APAM/L. However, we observed no effects on fitness-related endpoints (survival, hatching and growth) at concentrations up to 1500 mg L-1 APAM. Also, for the long-term exposure from late embryo to first feeding larvae stage, we observed reduced heart rate at 125 mg L-1. No consistent responses on survival, growth or respiration were observed except for the highest concentration tested (6000 mg L-1). Dispersion modelling based on expected and relevant discharged polymer concentrations and durations showed that predicted environmental concentrations were orders of magnitude lower than the concentrations tested in our experiments, indicating that 200 kDa APAM will have a limited probability of causing fitness-related effects on Atlantic cod ELS.

A machine vision system for zooplankton behavioural studies: a case study on the phototactic behaviour of sea lice (Lepeophtheirus salmonis) during sound and ultrasound stimuli.

Machine vision represents an accurate and easily verifiable method for observing live organisms and this technology is constantly evolving in terms of accessibility and cost. Motivated by the complexity of observing small-sized aquatic organisms in experimental systems, and the difficulties related to real-time observation, sampling and counting without interfering with the organisms, we here present a new method for observing behaviour and dispersion of non-sessile zooplankton organisms using a custom-made tank with an associated machine vision system. The system was used in an experiment where the aim was to assess the effect of sound and ultrasound on the phototactic behaviour of copepodite stages of the salmon louse (Lepeophtheirus salmonis). The experimental set-up is described, including a triangular test tank designed to create a sound pressure gradient, a mechanized camera movement system and a vision system with dedicated image processing software.

The effect of college education on mortality.

We exploit exogenous variation in years of completed college induced by draft-avoidance behavior during the Vietnam War to examine the impact of college on adult mortality. Our estimates imply that increasing college attainment from the level of the state at the 25th percentile of the education distribution to that of the state at the 75th percentile would decrease cumulative mortality for cohorts in our sample by 8 to 10 percent relative to the mean. Most of the reduction in mortality is from deaths due to cancer and heart disease. We also explore potential mechanisms, including differential earnings and health insurance.