Large scale patterns in vertical distribution and behaviour of mesopelagic scattering layers.

Recent studies suggest that previous estimates of mesopelagic biomasses are severely biased, with the new, higher estimates underlining the need to unveil behaviourally mediated coupling between shallow and deep ocean habitats. We analysed vertical distribution and diel vertical migration (DVM) of mesopelagic acoustic scattering layers (SLs) recorded at 38 kHz across oceanographic regimes encountered during the circumglobal Malaspina expedition. Mesopelagic SLs were observed in all areas covered, but vertical distributions and DVM patterns varied markedly. The distribution of mesopelagic backscatter was deepest in the southern Indian Ocean (weighted mean daytime depth: WMD 590 m) and shallowest at the oxygen minimum zone in the eastern Pacific (WMD 350 m). DVM was evident in all areas covered, on average ~50% of mesopelagic backscatter made daily excursions from mesopelagic depths to shallow waters. There were marked differences in migrating proportions between the regions, ranging from ~20% in the Indian Ocean to ~90% in the Eastern Pacific. Overall the data suggest strong spatial gradients in mesopelagic DVM patterns, with implied ecological and biogeochemical consequences. Our results suggest that parts of this spatial variability can be explained by horizontal patterns in physical-chemical properties of water masses, such as oxygen, temperature and turbidity.

Large mesopelagic fishes biomass and trophic efficiency in the open ocean.

With a current estimate of ~1,000 million tons, mesopelagic fishes likely dominate the world total fishes biomass. However, recent acoustic observations show that mesopelagic fishes biomass could be significantly larger than the current estimate. Here we combine modelling and a sensitivity analysis of the acoustic observations from the Malaspina 2010 Circumnavigation Expedition to show that the previous estimate needs to be revised to at least one order of magnitude higher. We show that there is a close relationship between the open ocean fishes biomass and primary production, and that the energy transfer efficiency from phytoplankton to mesopelagic fishes in the open ocean is higher than what is typically assumed. Our results indicate that the role of mesopelagic fishes in oceanic ecosystems and global ocean biogeochemical cycles needs to be revised as they may be respiring ~10% of the primary production in deep waters.

[Prediction of developmental problems and functional disabilities in infancy]. / Prediksjon av utviklingsvansker og funksjonshemning hos spedbarn.

Methods to identify developmental problems in children have been requested for a long time. We wanted to find out whether high scores of cumulative non-optimality during infancy indicated disability or developmental problems. In a prospective study, a population of children (n = 1,217) was followed from pregnancy until the age of four. Medical, motor, and neurological data, as well as information about attention and social interaction were added in a cumulative non-optimality score. Information about family and environment was also included. When the children were four years of age, multiple methods were used to identify those with disability and developmental problems. Complete data were obtained for 926 children. The predictive values of the instrument were based on children diagnosed as functionally disabled at the age of four (n = 32). The sensitivity was 87.5%, specificity 93%, positive predictive value 30.8% and negative predictive value was 99.5%. These values are higher than those of comparable methods. The method could be implemented in the normal Norwegian "child health centre" without difficulty. The discussion in this article focuses on whether or not the method should be implemented in the ordinary health care system.