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Aim: Water column acoustic backscatter is regularly registered during oceanographic surveys, providing valuable information on the composition and distribution of pelagic life in the ocean. We propose an objective approach based on functional data analysis to classify these acoustic seascapes into biogeographical regions. Location: Tropical South Atlantic Ocean off northeastern Brazil. Taxon: Sound‐scattering pelagic fauna detected with acoustic echosounders, principally small fish, crustaceans, squid and diverse gelatinous life‐forms. Methods: We use acoustic backscatter as a function of depth, simultaneously at three frequencies, to numerically describe the vertical distribution and composition of sound‐scattering organisms in the water column. This information is used to classify the acoustic seascape through functional principal component analysis. The analysis routine is tested and illustrated with data collected at 38, 70 and 120 kHz in waters affected by contrasting environmental conditions. Results: Acoustic seascape partitioning mirrored the distribution of current systems, fronts and taxonomically based regionalization. The study area was divided between slope‐boundary and open‐ocean waters, and between spring and fall hydrological regimes. Main Conclusions: The acoustic seascape consistency and the spatiotemporal coherence of the regions classified show that the method is efficient at identifying homogeneous and cohesive sound‐scattering communities. Comparisons against hydrological and biological regionalization prove that the method is reliable at delineating distinct pelagic ecosystems in a cost‐efficient and non‐intrusive way. [ABSTRACT FROM AUTHOR]

Ocean dynamics initiate the structure of nutrient income driving primary producers, and these, in turn, shape the distribution of subsequent trophic levels until the whole pelagic community reflects the physicochemical structure of the ocean. Despite the importance of bottom-up structuring in pelagic ecosystems, fine-scale studies of biophysical interactions along depth are scarce and challenging. To improve our understanding of such relationships, we analyzed the vertical structure of key oceanographic variables along with the distribution of acoustic biomass from multi-frequency acoustic data (38, 70, and 120 kHz) as a reference for pelagic fauna. In addition, we took advantage of species distribution databases collected at the same time to provide further interpretation. The study was performed in the Southwestern Tropical Atlantic of northeast Brazil in spring 2015 and autumn 2017, periods representative of canonical spring and autumn conditions in terms of thermohaline structure and current dynamics. We show that chlorophyll-a, oxygen, current, and stratification are important drivers for the distribution of sound scattering biota but that their relative importance depends on the area, the depth range, and the diel cycle. Prominent sound scattering layers (SSLs) in the epipelagic layer were associated with strong stratification and subsurface chlorophyll-a maximum. In areas where chlorophyll-a maxima were deeper than the peak of stratifications, SSLs were more correlated with stratification than subsurface chlorophyll maxima. Dissolved oxygen seems to be a driver in locations where lower oxygen concentration occurs in the subsurface. Finally, our results suggest that organisms seem to avoid strong currents core. However, future works are needed to better understand the role of currents on the vertical distribution of organisms. [ABSTRACT FROM AUTHOR]

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The submarine volcano eruption off El Hierro Island (Canary Islands) on 10 October 2011 promoted dramatic perturbation of the water column leading to changes in the distribution of pelagic fauna. To study the response of the scattering biota, we combined acoustic data with hydrographic profiles and concurrent sea surface turbidity indexes from satellite imagery. We also monitored changes in the plankton and nekton communities through the eruptive and post-eruptive phases. Decrease of oxygen, acidification, rising temperature and deposition of chemicals in shallow waters resulted in a reduction of epipelagic stocks and a disruption of diel vertical migration (nocturnal ascent) of mesopelagic organisms. Furthermore, decreased light levels at depth caused by extinction in the volcanic plume resulted in a significant shallowing of the deep acoustic scattering layer. Once the eruption ceased, the distribution and abundances of the pelagic biota returned to baseline levels. There was no evidence of a volcano-induced bloom in the plankton community. [ABSTRACT FROM AUTHOR]

Since 1996, the European Centre for Validation of Alternative Methods recommended the use of IgY for substitution of mammalian IgG to minimize harm situations in animal's experimentation for the production of polyclonal antibodies. In 1999, IgY technology was accepted by Federal Veterinarian Office of Swiss Government as an alternative method to support the care and healthy status of animals. Many publications show that IgY takes advantage over IgG to avoid interferences in several immunological assays for the fact that immune complexes that contain avian antibodies do not bind Fc or complement receptors on cells and IgY could replace a similar IgG. This knowledge has been the basis of this work that has consisted of the conjugation of highly pure IgY anti mouse IgG with FITC by covalent junction via primary free amino groups of immunoglobulins. The conjugate obtained showed a good molar ratio FITC/protein for a recommended performance. The optimal working dilution obtained for the particular conjugate was rational demonstrating to be useful as secondary antibody in enumeration of human cellular surface antigens. The cellular enumeration was assayed simultaneously with similar reagents from mammalian source and results showed no significant differences by statistical analysis. [ABSTRACT FROM AUTHOR]