Application of passive-acoustic telemetry to explore the behaviour of ballan wrasse (Labrus bergylta) and lumpfish (Cyclopterus lumpus) in commercial Scottish salmon sea-pens

A passive-acoustic telemetry system was used for the first time for the fine-scale, three-dimensional tracking of individual cleaner fish in commercial Scottish salmon sea-pens in full commercial operation. The aim was to test the system performance and provide baseline data on the comparative distribution and swimming activity of individual ballan wrasse and lumpfish under standard farm practices with the long-term aim of informing stocking and husbandry strategies. In March 2015, wild ballan wrasse (Labrus bergylta) (115 ± 20 g; n = 13) and farmed lumpfish (Cyclopterus lumpus) (281 ± 42 g; n = 13) previously deployed in June–October 2014 were recaptured, implanted with acoustic tags pinging every 6–12 s and released into their original sea cage holding Atlantic salmon (Q2 2014; 2059 ± 35 g mean-weight). Control tags were deployed in cleaner fish hides to validate the system performance. Positional data from nine specimens per species were analysed from March 24th to June 1st 2015, during which time water temperature rose from 7.2 to 9.1 °C and water salinity averaged 26.8 ± 1.5 ppt at 4 m depth. The accuracy of the acoustic positions averaged 0.6 m across the three dimensions of all control tags and was < 1 m in 93% of all cases. Significant differences in the distribution and activity of ballan wrasse and lumpfish were observed. Ballan wrasses spent 60 ± 2% of the day-time at or below 15 m, were positioned at significantly shallower depths at night and seldom used the hides provided despite an apparent resting behaviour at the pen bottom and corners. In comparison, lumpfish spent over 80% of the time above 10 m, used hides extensively and preferentially at night (50.1 ± 2.1% at night), but to a lesser extent when the water temperature increased. The acoustic tracking system proved to be an effective tool for visualising cleaner fish behaviour under challenging farm conditions, and the study highlights the critical role of hides in cleaner fish husbandry. Overall, the study quantified species-specific cleaner fish distribution in salmon net-pens supporting distinct interactions with the salmon stock and seasonal behaviour profiles. The results support the current commercial strategy of using two cleaner fish species against sea lice and the need for species-specific management strategies to optimise delousing activity

Sustainable production and use of cleaner fish for the biological control of sea lice: recent advances and current challenges

Currently, cleaner fish are one of the most widely used sea lice control strategies in Atlantic salmon aquaculture. Two species are currently being farmed in North Atlantic countries, ballan wrasse (Labrus bergylta) and lumpfish (Cyclopterus lumpus), and the sector in most countries is rapidly expanding towards self-sufficiency. The species are very different both in terms of their biology and life histories and, consequently, production and husbandry methods must be tailored to each species. There are numerous health challenges currently experienced in both species, with bacterial and parasitic diseases being the most prevalent, and cohabitation with salmon may increase the risk of disease. Good husbandry and routine health monitoring are essential, although treatment is often required when disease outbreaks occur. Ballan wrasse and lumpfish are both proven to be effective salmon delousers, although delousing efficacy can be variable in farmed fish; the provision of suitable habitat and acclimation to net-pen conditions may encourage natural behaviours, including delousing, and the use of operational welfare indicators can highlight potential welfare issues. Cleaner fish research is progressing rapidly, although much of the basic knowledge regarding the species’ biology remains unknown. The simultaneous domestication of two new marine aquaculture species is a significant challenge demanding sustained effort and funding over a prolonged period of time. Research must focus on enhancing the robustness of the farmed stocks and increasing hatchery outputs to meet the urgent demands from the salmon sector and protect wild stocks from overfishing

Pre-deployment acclimatisation of farmed ballan wrasse (Labrus bergylta) to sea-cage conditions promotes behaviour analogous to wild conspecifics when used as cleaner fish in Atlantic salmon (Salmo salar) farms

Ballan wrasse (Labrus bergylta) are used as cleaner fish in commercial Atlantic salmon farming to remove ectoparasitic sea lice. While the delousing performance of wild wrasse is usually good, that of farmed wrasse is variable, possibly because of different conditions in hatcheries and sea cages. In this study, three passive-acoustic telemetry (PAT) trials were conducted at a salmon farm to compare the behaviour of wild and farmed wrasse and test the effect of acclimatising farmed wrasse to sea-cage conditions before deployment. Up to 40 fish were monitored simultaneously for 60–124 days by triangulating tag positions within a hydrophone array every 6–10 s. This data was used to assess fish depth and preferred cage locations and calculate activity, orientation and home ranges. Wild wrasse occupied shallower depths (13.3 ± 2.4 m) than farmed wrasse, which remained near the bottom of the cages (18.2 ± 1.7 m). Swimming activity was higher in wild wrasse with significant diurnal variations due to nocturnal quiescence on 68% of observed days. Wild wrasse rapidly developed large home ranges (616.8 ± 110.1 m2), preferring cage corners. Hatchery-and-sea-cage acclimatisation improved the behaviour of farmed wrasse; they rapidly moved up the water column (9.08 ± 2.05 m after 1 week) and established home ranges (514.3 ± 146.6 m2), and they developed diurnal activity patterns, which may indicate a positive response to acclimatisation. Acclimatising farmed ballan wrasse to sea-cage conditions positively improved and encouraged behaviours similar to those seen in wild wrasse, including diurnal rhythms and the establishment of home ranges, and is recommended for all farmed wrasse prior to deployment to improve delousing performance

Measurement of erythrocyte membrane mannoses to assess splenic function

ACKNOWLEDGEMENTS This work was funded by Aberdeen University Development Trust and Friends of Anchor. The University of Aberdeen is applying for a patent based on this work. Aberdeen University Development Trust (GrantNumber(s): DB10452-11) Friends of Anchor (GrantNumber(s): RS 2018 001)Peer reviewedPublisher PD

High mannose N-glycans on red blood cells as phagocytic ligands, mediating both sickle cell anaemia and resistance to malaria

Acknowledgements We are grateful for the assistance provided by both the Microscopy and Histology Core Facility, and the Iain Fraser Cytometry Centre, at the University of Aberdeen. We thank Ann Wheeler and Matt Pearson from Edinburgh Super-Resolution Imaging Consortium for technical support with 3D SIM microscopy. We also thank Janet A. Willment and Bernard Kerscher, supervised by G.D.B., for providing the Fc fusion proteins, Jeanette A. Wagener, supervised by Neil A.R.G. Gow, for providing high purity chitin, Jan Westland for obtaining blood samples and Paul Crocker for useful discussions. Principal funding for this project was provided by Wellcome Trust grant 094847 (R.N.B, L.P.E, M.A.V). In addition, support was provided by Biotechnology and Biological Sciences Research Council grants BBF0083091 (A.D. and S.M.H.) and BBK0161641 (A.D. and S.M.H.), Wellcome Trust grant 082098 (A.D.), Wellcome Trust grants 97377, 102705 (G.D.B) and funding for the MRC Centre for Medical Mycology at the University of Aberdeen MR/N006364/1 (G.D.B).Non peer reviewe

Red blood cell mannoses as phagocytic ligands mediating both sickle cell anaemia and malaria resistance

Acknowledgements We are grateful for the assistance provided by both the Microscopy and Histology Core Facility, and the Iain Fraser Cytometry Centre, at the University of Aberdeen. We thank Ann Wheeler and Matt Pearson from Edinburgh Super-Resolution Imaging Consortium for technical support with 3D SIM microscopy. We also thank Janet A. Willment and Bernard Kerscher, supervised by G.D.B., for providing the Fc fusion proteins, Jeanette A. Wagener, supervised by Neil A.R.G. Gow, for providing high purity chitin, Jan Westland for obtaining blood samples and Paul Crocker for useful discussions. Principal funding for this project was provided by Wellcome Trust grant 094847 (R.N.B., L.P.E., M.A.V.). In addition, support was provided by Biotechnology and Biological Sciences Research Council grants BBF0083091 (A.D. and S.M.H.) and BBK0161641 (A.D. and S.M.H.), Wellcome Trust grant 082098 (A.D.), Wellcome Trust grants 97377, 102705 (G.D.B.), and funding for the MRC Centre for Medical Mycology at the University of Aberdeen MR/N006364/1 (G.D.B.).Peer reviewedPublisher PD

MeCP2 binds to nucleosome free (linker DNA) regions and to H3K9/H3K27 methylated nucleosomes in the brain

Methyl-CpG-binding protein 2 (MeCP2) is a chromatin-binding protein that mediates transcriptional regulation, and is highly abundant in brain. The nature of its binding to reconstituted templates has been well characterized in vitro. However, its interactions with native chromatin are less understood. Here we show that MeCP2 displays a distinct distribution within fractionated chromatin from various tissues and cell types. Artificially induced global changes in DNA methylation by 3-aminobenzamide or 5-aza-2′-deoxycytidine, do not significantly affect the distribution or amount of MeCP2 in HeLa S3 or 3T3 cells. Most MeCP2 in brain is chromatin-bound and localized within highly nuclease-accessible regions. We also show that, while in most tissues and cell lines, MeCP2 forms stable complexes with nucleosome, in brain, a fraction of it is loosely bound to chromatin, likely to nucleosome-depleted regions. Finally, we provide evidence for novel associations of MeCP2 with mononucleosomes containing histone H2A.X, H3K9me2 and H3K27me3 in different chromatin fractions from brain cortex and in vitro. We postulate that the functional compartmentalization and tissue-specific distribution of MeCP2 within different chromatin types may be directed by its association with nucleosomes containing specific histone variants, and post-translational modifications

Are we killing them with kindness? Evaluation of sustainable marine wildlife tourism

The increasing popularity of marine wildlife tourism (MWT) worldwide calls for assessment of its conservation outcomes and the development of appropriate management frameworks to ensure the conservation of the species and habitats involved as well as the long-term sustainability of this industry. While many studies have examined the positive and/or negative implications of particular forms of MWT, few have attempted to identify factors of concern shared across different types of marine tourism, or examine their implications for sustainability in a broader perspective. We reviewed the existing literature to highlight common impacts on animal behaviour, health and ecology, and to identify successful cases based on minimal negative affects and/or lack of chronic/ irreversible impacts on target species or habitats. To ensure the achievement of both economic and ecologic objectives, the following steps should be integrated in MWT management: 1) Increase of research on the biology and ecology of target species/habitat and application of relevant information for the development of suitable policies, frameworks and management strategies; 2) Structured enforcement of existing policies and enhancement of ecological awareness of visitors through active education; 3) Application of an adaptive management framework to continuously improve the codes of conduct employed; 4) Involvement of different stakeholders and local communities in the development and improvement of the MWT activity. Combining these strategies with the extrapolation of frameworks and policies from cases where adverse ecological impacts have been addressed and successfully resolved can further contribute in ensuring the long-term health and conservation of the species/ habitats involved in MWT activities