Calcification rates of a massive and a branching coral species were unrelated to diversity of endosymbiotic dinoflagellates.

BACKGROUND: To explore the possibility that endosymbiotic dinoflagellates (Symbiodiniaceae) are associated with coral calcification rates, we investigated the diversity of symbiotic algae in coral colonies with different calcification rates within massive and branching corals (Porites australiensis and Acropora digitifera). METHODS AND RESULTS: Genotyping symbiotic algae from colonies with different calcification rates revealed that all the colonies of both species harbored mainly Cladocopium (previously clade C of Symbiodinium). The Cladocopium symbionts in P. australiensis were mainly composed of C15 and C15bn, and those in A. digitifera of C50a and C50c. We did not detect clear relationships between symbiont compositions and calcification rates within the two coral species. CONCLUSIONS: Our results suggest that different coral calcification rates within species may be attributed to genetic factors of coral hosts themselves and/or within symbiont genotypes.

Whole transcriptome analysis of demersal fish eggs reveals complex responses to ocean deoxygenation and acidification.

Ocean acidification and deoxygenation co-occur in marine environments, causing deterioration of marine ecosystems. However, effects of compound stresses on marine organisms and their physiological coping mechanisms are largely unknown. Here, we show how high pCO2 and low dissolved oxygen (DO) cause transcriptomic changes in eggs of a demersal fish (Sillago japonica), which are fully exposed to such stresses in natural environment. Overall gene expression was affected more strongly by low DO than by high pCO2. Enrichment analysis detected significant stress responses such as glycolytic processes in response to low DO. Increased expression of a group of glycolytic genes under low DO conditions is presumably because oxygen depletion disables the electron transfer pathway, complementing ATP production in the glycolytic pathway. Contrary to expectations, apparent mitigation of gene expression changes was dominant under combined stress conditions, and may represent an innate fish adaptive trait for severe environments.

Do solar cycles explain the emergence of COVID-19? Neutron count comparison between the solar minima of 2008-2009 and 2019-2020.

Cosmic rays are believed to be mutagenic and can stimulate virus mutation through point mutations. Neutron count on Earth ground stations is a reliable proxy to quantify cosmic ray flux. A previous study reported that the maximum flux of cosmic rays in November 2019 could be related to the emergence of COVID-19 (late November to early December). Using the latest neutron count data, this study investigated if the data from 2019 to 2020 could specifically explain the emergence of pandemic (COVID-19). The results indicate that there is no significant difference between the previous two last solar minima datasets (2008-2009 and 2019-2020; n = 24, p = 0.60). This suggests that the solar minima of 2019-2020 did not experience an increase in cosmic rays and the emergence of COVID-19 could not be solely explained by cosmic ray flux caused by solar cycles (space weather change).