Search Results (3)

Analytical imaging via synchrotron analysis was used to study sagittal otoliths of four freshwater pipefish species exhibiting amphidromous or freshwater resident lifestyles. We undertook a hyperfine elemental scanning of a 25 μm diameter length area centred on the core, namely the pre-hatch zone, corresponding to the sagitta formed during embryogenesis. We analysed calcium (Ca), strontium (Sr), manganese (Mn), chromium (Cr), cobalt (Co), nickel (Ni) and sulphur (S), with the latter serving to count growth increments. Whatever the species, a Ca pit consistently marked the core; the amphidromous species exhibited Mn enrichment at the core and the sagitta formed a week before hatching. These results illustrate common otolith formation mechanistic processes. Sr and heavy metals’ signals in the pre-hatch zone were compared to their signal in the edge of the otolith, an area encompassing the adult freshwater (adFW) environmental signature. We found that Co and Ni otolith signals had no relation to environmental conditions, but it is worth looking into Cr as a marker of early-life environment. While we caution against the use of a Sr:Ca ratio for life history interpretations at the core because of the Ca pit, the Sr signal analysis uncovered possible variations in the parental behaviour that potentially trigger newly-hatched juvenile migration to sea or residency. Finally, our results demonstrate that the microchemistry of otolith formation during early development is a melting of maternal signal during egg yolk elaboration, of the environmental signal during egg incubation, and of individual physiology during early growth. Full article

Family Parvoviridae consists of small, non-enveloped viruses with linear, single-stranded DNA genomes of approximately 4-6 kilobases, subdivided into three subfamilies, Parvovirinae, Densovirinae, and Hamaparvovirinae, and unassigned genus Metalloincertoparvovirus. Parvoviruses of aquatic animals infect crustaceans, mollusks, and finfish. This review describes these parvoviruses, which are highly host-specific and associated with mass morbidity and mortality in both farmed and wild aquatic animals. They include Cherax quadricarinatus densovirus (CqDV) in freshwater crayfish in Queensland, Australia; sea star-associated densovirus (SSaDV) in sunflower sea star on the Northeastern Pacific Coast; Clinch densovirus 1 in freshwater mussels in the Clinch River, Virginia, and Tennessee, USA, in subfamily Densovirinae; hepatopancreatic parvovirus (HPV) and infectious hypodermal and hematopoietic necrosis virus (IHHNV) in farmed shrimp worldwide; Syngnathid ichthamaparvovirus 1 in gulf pipefish in the Gulf of Mexico and parts of South America; tilapia parvovirus (TiPV) in farmed tilapia in China, Thailand, and India, in the subfamily Hamaparvovirinae; and Penaeus monodon metallodensovirus (PmMDV) in Vietnamese P. monodon, in unassigned genus Metalloincertoparvovirus. Also included in the family Parvoviridae are novel parvoviruses detected in both diseased and healthy animals using metagenomic sequencing, such as zander parvovirus from zander in Hungary and salmon parvovirus from sockeye salmon smolts in British Columbia, Canada. Full article

Indo-Pacific tropical island streams are home to freshwater pipefish (Microphis spp., Syngnathidae). Otoliths were used to uncover life history traits in four species, including a New Caledonian endemic. All four species present the same methodological challenge: their otoliths are small, fragile and mute for growth marks using basic observation tools. Strontium (Sr) is calcium substituent in the mineral lattice, driven by salinity conditions, and thus useful to study diadromous migrations. Synchrotron-based scanning X-ray fluorescence 2D high-resolution mapping allowed us to tackle the global and hyperfine strontium (Sr) distribution. We developed analytical imaging processes to retrieve biological information from otoliths from the data generated via synchrotron analysis. We uncovered plasticity in the life cycle: all species were amphidromous, apart from some freshwater residents from New Caledonia. Understanding life cycle modalities is crucial to categorize species distribution limits and to implement adapted conservation measures, especially when endemic species are at stake. 2D fine-scale images outlined the heterogeneity of Sr distribution: in addition to the trivial Sr incorporation driven by environmental ionic conditions, there is an unusual mosaic arrangement of Sr distribution and we hypothesize that biological control, especially growth during the early life stages, may sometimes overrule stoichiometry. This shows that it is worth studying otolith formation and element integration at imbricated scales, and our methods and results provide a strong basis for future works and prospects in otolith science. Full article