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Hybridization between species and the establishment of hybridization barriers can influence the diversification of species. Antarctic notothenioid fishes represent a prime example of marine adaptive radiation that diversified in the icy waters of Antarctica from an ancestral population that innovated antifreeze glycoproteins. The processes by which Antarctic notothenioid species evolved, however, remain elusive, and interspecific hybridization or the establishment of hybridization barriers between lineages may have influenced species diversification. To evaluate the current hybridization potential of notothenioids, we performed an experimental in vitro fertilization cross between two sympatric and congeneric notothen species using oocytes from the bullhead notothen Notothenia coriiceps and sperm from the marbled notothen N. rossii. Resulting embryos developed to late gastrula/early neurula stages and then suddenly died. Genetic analyses of embryos and parents demonstrated that the embryos lacked detectable paternal DNA and were thus gynogenetic. While premating barriers are likely to exist between the two species, this experiment suggests a strong postmating, prezygotic reproductive barrier preventing hybridization between the sister species due to gametic incompatibility in this directional cross. Our study provides novel information on mechanisms that may have contributed to the divergence and maintenance of these two ecologically important congeneric species. [ABSTRACT FROM AUTHOR]

This document is a correction notice for an article titled "Hybridization barriers between the congeneric antarctic notothenioid fish Notothenia coriiceps and Notothenia rossii" published in the journal Polar Biology. The correction adds the missing affiliation for one of the authors, Margaret Streeter, who is affiliated with the College of Natural Science and Mathematics at the University of Houston. The original article has been corrected. The publisher, Springer Nature, remains neutral regarding jurisdictional claims and institutional affiliations. The authors of the article are Thomas Desvignes, Nathalie R. Le François, Margaret Streeter, Jacob Grondin, Emily Singer, John H. Postlethwait, and H. William Detrich III. [Extracted from the article]

This study provides new and practical information to implement the use of photoperiodic manipulation for the control of the sexual maturation of Canadian 6+ Atlantic wolffish (Anarhichas lupus) and 3+ first-time spawners spotted wolffish (Anarhichas minor) from Canadian and Norwegian populations. Wolffish reproductive cycle (gametogenesis and oocyte maturation and spermiation) was monitored for 23 consecutive months. Control groups were held under a 12-month simulated natural photoperiod and treatment groups under an 8-month compressed photoperiod. Plasma sex steroid concentrations (estradiol-17β and 11-ketotestosterone), oocyte diameter growth, and milt production were assessed monthly. For all groups under study, fish subjected to the compressed photoperiod spawned 2-6 months earlier than the controls. Complete out-of-shift cycle was not achieved based on the completion of two reproduction cycles, and this is briefly discussed. Photoperiod treatment induced temporal shifts in sex steroid profiles, which are the likely mediators of altered timing of ovulation/final maturation. Photoperiod has a strong influence on the timing of wolffish maturation and could be used as an efficient and inexpensive tool to secure wolffish reproduction operations (year-round supply of egg and milt and/or timing with optimal temperature regimes). [ABSTRACT FROM AUTHOR]

The bioremediation capacities of Palmaria palmata and Ulva lactuca for removing dissolved nutrients in a cold-seawater fully recirculated ecosystemic representation of an estuarine aquatic habitat were evaluated. The seaweeds were cultured in the laboratory based on environmental conditions observed in a large-scale aquarium representing the marine ecosystem of the Gulf of Saint-Lawrence (Québec, Canada), i.e., salinity of 24 PSU, 5 and 10 °C, and under three combinations of high nitrate (NO3−) and phosphate (PO43−) concentrations (2865:195, 3570:242, and 4284: 291 μM). Neither nutrient levels nor temperature significantly changed nitrate and phosphate uptake rates (0.65 ± 0.15 and 1.76 ± 0.59 mg N gDW−1 day−1 and 0.14 ± 0.11 and 0.32 ± 0.21 mg P gDW−1 day−1 for P. palmata and U. lactuca, respectively). Growth rate of P. palmata was independent of temperature and nutrient concentrations with a mean of 0.64 ± 0.18% FW day−1. Ulva lactuca expressed its highest growth rate (2.81 ± 0.72% FW day−1) at 10 °C and intermediate nutrient concentration. C/N ratio was < 10 for both species before and after the experiment, indicating tissue nutrient enrichment possibly limiting nutrient uptake and growth. Under cold temperatures and high dissolved nutrient concentrations, U. lactuca is the leading candidate for bioremediation. [ABSTRACT FROM AUTHOR]

Interspecific hybridization or barriers to hybridization may have contributed to the diversification of Antarctic icefishes (Channichthyidae), but data supporting these hypotheses is scarce. To understand the potential for hybridization and to investigate reproductive isolating mechanisms among icefish species, we performed in vitro fertilization experiments using eggs from a female blackfin icefish Chaenocephalus aceratus and sperm from a male of another genera, the ocellated icefish Chionodraco rastrospinosus. Sequencing of genomic and mitochondrial DNA confirmed the intergeneric hybrid nature of resulting embryos which successfully developed and hatched as active larvae at about four and a half months during the Antarctic winter. This result demonstrates the compatibility of gametes of these two species and the viability of resulting zygotes and larvae. Due to logistic constraints and the slow developmental rate of icefishes, we could not test for long-term hybrid viability, fertility, fitness, or hybrid breakdown. Analysis of our fishing records and available literature, however, suggests that the strongest barriers to hybridization among parapatric icefish species are likely to be behavioral and characterized by assortative mating and species-specific courtship and nesting behaviors. This conclusion suggests that, in long-lived fish species with late sexual maturity and high energetic investment in reproduction like icefishes, pre-mating barriers are energetically more efficient than post-mating barriers to prevent hybridization. [ABSTRACT FROM AUTHOR]