Ontogenetic changes in the diet of L. forbesi: insights from fatty acid and stable isotope analysis

The diet of L. forbesi in Scottish waters was subject to ontogenetic changes as shown by fatty acid and stable isotope analysis. Crustaceans were more frequently found in stomachs of immature squid smaller than 150 mm mantle length. With increasing size ( > 150 mm) and maturity fish becamemore prominent in the diet. Seasonal differences in the diet were also found but seemed to be linked to seasonal changes in squid size. Prey type and species composition also varied slightly between different regions. Differences between size and region were reflected in fatty acid profiles of mainly the digestive gland tissue. High levels of the saturated fatty acid 16:0 and the polyunsaturated fatty acids 20:5n-3 and 22:6n-3, which are typical for fatty acid signatures of many crustacean species, were found in tissues of smaller immature squid. Higher levels of the monounsaturated fatty acids 16:1n-7, 20:1* and polyunsaturated fatty acids of the linoleic family (C18), which are typical forfish prey species, were found in squid of larger sizes and higher maturity stages. Regional differences found for fatty acid profiles of the digestive gland suggested a significant difference in origin of fatty acids thus indicating different diets. In comparing the fatty acid profiles of squid to those of putative prey species of L. forbesi, it was apparent that gadid species Trisopterus minutus, Micromesistius poutassou and Gadus morhua, were an important component of the diet ofL. forbesi. With increasing size of the predator however the composition of fish species in the diet shifted more towardsGadiculus argenteus, Trachurus trachurus and Sebastes marinus. Results of quantitative fatty acid analysis on the estimate of the contribution of each prey species to the diet also reflected this shift in the importance of different prey species with increasing predator size. Due to slower turnover rates in muscle, changes in carbon and nitrogen stable isotope ratios with diet were more pronounced in this tissue. Smaller squid showed the lowest δ15N ratios thus feeding on the lowest trophic level of all squid examined. δ 13C ratios were the most depleted for small squid indicating that small squid feed on prey closer to the carbon source in the food chain. Stable isotope analysis also showed that squid with fish remains in their stomachs showed higher ratios of nitrogen and less depleted carbon ratios than squid feeding on crustaceans. Comparisons of isotope levels of squid and putative prey species identified blue whiting and silvery pout as putative prey species of bigger sized squid. Small squid seemed to feed on the same trophic level and all other prey species examined were always similar or higher in isotope ratios than squid of any size

Close encounters - microplastic availability to pelagic amphipods in sub-antarctic and antarctic surface waters

This study investigated the distribution of plastic debris from the Atlantic portion of the Sub-Antarctic to the Antarctic Peninsula. This region is home to some of the highest concentrations of zooplankton biomass but is also threatened by increasing shipping traffic from fishing and the growing tourism market. Samples were collected using a surface-towed neuston net during the Austral summer 2018, aboard the RRS James Clark Ross. Using Fourier Transform Infrared Spectrometry it was found that 45.6% of the plastic particles isolated from seawater samples were sampling contamination, originating predominantly from the ship. Of the remaining particles, both low density (polyethylene, polypropylene) and high-density (phenoxy and epoxy resins) polymers were found in the surface water suggesting both long-range and local sources of origin. Whilst we found that micro and mesoplastic concentrations in seawater were significantly low (0.013 ± 0.005n/m3) compared to global averages, they were higher along the Antarctic Peninsula than the open ocean (Sub-Antarctic) stations. The potential availability of micro and mesoplastics (MP) to pelagic amphipods was explored, using an observed encounter rate (OER) and a possible encounter rate (PER). The total OER (0.8%) was higher than the PER (0.15%), suggesting that even at low concentrations, microplastics are encountered, and potentially consumed, by amphipods. This study highlights the need to prioritise regions of high zooplankton abundance and to investigate both water and biota to build up a picture of plastic pollution and its potential interaction with the Antarctic Ecosystem

Current status of using beaks to identify cephalopods: III International Workshop and training course on Cephalopod beaks, Faial island, Azores, April 2007

The identification of cephalopods using their beaks is still a difficult technique. To increase our knowledge of this technique and stimulate a new generation of beak experts, the III International beak workshop and training course was organized in Faial, Azores Islands in 2007. We briefly review the activities of the workshop, including the identification procedure of lower beaks of cephalopods from predators with emphasis on cetaceans, seals, fish and seabirds; provision of basic knowledge to young researchers interested in the study area; identification of recent developments in beak research; and discussion of the main problematic issues. The families that need particular attention are Brachioteuthidae, Chiroteuthidae, Cranchiidae, Cycloteuthidae, Mastigoteuthidae, Octopoteuthidae, Promachoteuthidae, Onychoteuthidae (particularly the genus Walvisteuthis), Mastigoteuthidae and Cirroteuthidae. The stable isotopic signature of beaks is capable of revealing new trophic relationships and migrations. Future work should focus on: a) obtaining more cephalopod material from research cruises; b) promoting a close and continuous collaboration between beak experts and cephalopod taxonomists and; c) developing new, and updated, beak guides

Continuous moulting by Antarctic krill drives major pulses of carbon export in the north Scotia Sea, Southern Ocean

Antarctic krill play an important role in biogeochemical cycles and can potentially generate high-particulate organic carbon (POC) fluxes to the deep ocean. They also have an unusual trait of moulting continuously throughout their life-cycle. We determine the krill seasonal contribution to POC flux in terms of faecal pellets (FP), exuviae and carcasses from sediment trap samples collected in the Southern Ocean. We found that krill moulting generated an exuviae flux of similar order to that of FP, together accounting for 87% of an annual POC flux (22.8 g m−2 y−1). Using an inverse modelling approach, we determined the krill population size necessary to generate this flux peaked at 261 g m−2. This study shows the important role of krill exuviae as a vector for POC flux. Since krill moulting cycle depends on temperature, our results highlight the sensitivity of POC flux to rapid regional environmental change

The abundance of 44Ti in core collapse supernovae : Measuring the 44Ti(α, p)47V reaction

Publisher PD

Primary aldosteronism: A Japanese perspective

Primary aldosteronism (PA) is the most common cause of secondary hypertension, accounting for 10% of all hypertension. Far from being benign, hypertension due to PA is associated with high cardiovascular morbidity and mortality. However, PA is still underdiagnosed in general practice. Recent reports strongly recommend that identifying patients with PA is cost-beneficial based on improved cardiovascular outcomes afforded by specific surgical and medical treatment. This review provides an update of PA including controversial aspects of diagnosis and treatment

Study of the Ti-44(alpha, p)V-47 reaction and implications for core collapse supernovae

Peer reviewe

Addressing Grand Challenges in Earth Observation Science: The Earth Observation Data Centre for Water Resources Monitoring

Earth observation is entering a new era where the increasing availability of free and open global satellite data sets combined with the computing power offered by modern information technologies opens up the possibility to process high-resolution data sets at global scale and short repeat intervals in a fully automatic fashion. This will not only boost the availability of higher level earth observation data in purely quantitative terms, but can also be expected to trigger a step change in the quality and usability of earth observation data. However, the technical, scientific, and organisational challenges that need to be overcome to arrive at this point are significant. First of all, Petabyte-scale data centres are needed for storing and processing complete satellite data records. Second, innovative processing chains that allow fully automatic processing of the satellite data from the raw sensor records to higher-level geophysical products need to be developed. Last but not least, new models of cooperation between public and private actors need to be found in order to live up to the first two challenges. This paper offers a discussion of how the Earth Observation Data Centre for Water Resources Monitoring (EODC) – a catalyser for an open and international cooperation of public and private organisations – will address these three grand challenges with the aim to foster the use of earth observation for monitoring of global water resources