Can mesopelagic mixed layers be used as feed sources for salmon aquaculture?

Salmon aquaculture is in great need of good quality balanced protein and lipid sources, particularly marine omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA), to sustain a further development of the industry. One possibility is to harvest mesopelagic marine layers. Therefore, the current project analysed mesopelagic hauls from three cruises (November 2015 to October 2016) collected from the inner fjord systems around Bergen and in open-waters off Tromsø and Ålesund, Norway. Jellyfish, krill, shrimps and small amounts of the mesopelagic fish, Maurolicus muelleri and Benthosema glaciale, dominated the mixed mesopelagic hauls. Lipid content ranged between 35-40% of dry matter with two samples from autumn being 21 and 13%, with the latter haul being almost exclusively krill. In contrast, M. muelleri and B. glaciale had lipid contents of around 54 and 47% respectively. Overall, lipid was a relatively good source of marine n-3 LC-PUFA, EPA and DHA, being in the range of 15–20% of fatty acids which increased in lean samples. However, many of the trawl hauls contained wax esters (7 out of 9 hauls), equivalent to 40% or more of the lipid, with B. glaciale containing almost 90% wax esters of lipid. This presents a challenge if used in salmon diets, as their utilisation is limited. Protein contents ranged between 45-50%, increasing in lean samples. The essential amino acid content was well above the requirements for Atlantic salmon (Salmo salar) with B. glaciale generally containing higher levels compared to M. muelleri. Leucine, lysine and valine levels were particularly high. Hauls from open-waters contained mixtures of amphipods resulting in cadmium levels exceeding the maximum allowable level in feedstuffs. Arsenic levels were high or borderline. Reducing crustacean mix in hauls appear to be the only option to reduce these levels, whereas mesopelagic fish contained low levels of all heavy metals. In summary, the mesopelagic layer contains protein and lipid sources that could supply raw materials to the salmon aquaculture industry. However, high levels of wax esters, cadmium and arsenic needs to be addressed

The North Atlantic Ocean as habitat for Calanus finmarchicus : environmental factors and life history traits

This paper addresses relationships between the distribution and abundance of zooplankton and its habitat in the northern North Atlantic Ocean. Distributions of ten representative zooplankton taxa, from recent (2000-2009) Continuous Plankton Recorder data, are presented, along with basin-scale patterns of annual sea surface temperature and phytoplankton color. The distribution patterns represent the manifestation of very different physiological, life history and ecological interactions of each taxon with the North Atlantic habitat characteristics. The paper then focuses on a pan-Atlantic compilation of demographic and life history information for the planktonic copepod, Calanus finmarchicus, perhaps one of the most ecologically important and certainly the most studied zooplankton species in the North Atlantic. Abundance, dormancy, egg production and mortality in relation to temperature and phytoplankton biomass, using chlorophyll a as a proxy, are analyzed in the context of understanding factors involved in determining the distribution and abundance of C. finmarchicus across its range. Several themes emerge: (1) transport of C. finmarchicus is from the south to the north in the northeast Atlantic, but from the north to the south in the western North Atlantic, which has implications for understanding population responses to climate forcing on coastal shelves, , (2) recruitment to the youngest copepodite stages occurs during or just after the phytoplankton bloom in the east while it occurs after the bloom in many western sites, (3) while the deep basins in the Labrador Sea and Norwegian Sea are primary sources of C. finmarchicus production, the western North Atlantic marginal seas have an important role in sustaining high C. finmarchicus abundance on the western North Atlantic shelves, (4) differences in mean temperature and chlorophyll concentration between the western and eastern North Atlantic are reflected in regional differences in female body size and egg production responses, (5) differences in functional responses in egg production rate may reflect genetic differences between western and eastern populations, (6) dormancy duration is generally shorter in the deep waters adjacent to the lower latitude western North Atlantic shelves than in the east, and (7) differences in stage-specific mortality rates are related to bathymetry, temperature and potential predators, notably the abundance of congeners Calanus hyperboreus and C. glacialis, which likely feed on early life stages of C. finmarchicus. Two modeling approaches have previously been used to interpret the abundance and distribution of C. finmarchicus in relation to the North Atlantic habitat. A statistical approach based on ecological niche theory and a dynamical modeling approach, based on knowledge of spatial population dynamics and life history and implemented by recent developments in coupled physical-life cycle modeling. The strengths and weaknesses of each approach are discussed. A synthesis of the two modeling approaches to predict North Atlantic zooplankton species shifts, not only for C. finmarchicus, but also for other major taxa, is advocated. While the computational resource requirements and lack of species-specific life history information for physical-biological modeling hinder full application for many zooplankton taxa, use of the approach, where possible, to understand advective influences will provide insight for interpretation of statistical predictions from species distribution models

High resolution x-ray characterization of periodically domain-inverted nonlinear optical crystals

A high-resolution triple-axis diffractometer has been used for the structural characterization of periodically domain-inverted nonlinear optical crystals of KTiOPO4 and LNbO3. Striations have been revealed in high strain-sensitivity multiple-crystal topographs of the domain-inverted regions of both these samples and these are dominated by orientation contrast. The combination of high-resolution reciprocal-space mapping and topography has shown that the extended diffraction streak in the q[210] direction for domain-inverted LiNbO3 originates from the "minutely misoriented structure" which is related to the original configuration of dislocations. The reason for the generation of the structural imperfections via the domain-inversion processing is interpreted in terms of the converse piezoelectric effect

Regional dynamics of Calanus in the Norwegian Sea in response to ocean climate in 1997

International audienc

Characteristics of the OPG System USIG Quasiphase-Matched Nonlinear Crystals for 1.6 μm CO2 Dial

We have developed a direct detection 1.6 μm differential absorption lidar (DIAL) technique to perform range-resolved measurements of vertical CO2 concentration profiles in the atmosphere. Our 1.6 μm DIAL system consists of the optical parametric generator (OPG) and amplifier (OPA) transmitter that excited by the LD pumped Nd:YAG laser with high repetition rate (500 Hz). The OPG system consists of a quasi-phase-matched (QPM) crystal and does not need a cavity. The output power of the OPA system is 6 mJ, the full width at half maximum (FWHM) of the spectrum is about 280 MHz and spectrum purity is 91.0 +- 0.2 ~ 0.5%. CO2 concentration error from fluctuation of the spectrum purity is 0.3% at 6 km altitude and 0.4 % at 10 km altitude