Comparison of Lipid Profile in Three Species of Myctophids from the South West Coast of Kerala, India

Exploring the macrominerals and heavy metals profile of deep-sea fishes: A pioneering study on trawl bycatch and discards in the Arabian Sea

This study assesses macrominerals (Na, K, Ca, Mg, P) and heavy metals (As, Cd, Cr, Cu, Ni, Pb, Se, Sn, Mn, Co, Fe, and Zn) content of deep-sea fish bycatch in the Arabian Sea, offering insights into their nutritional value, toxicant levels and health implications. Variations in Ca, K, P, Mg, and Na levels across species highlight mineral diversity. Setarches guentheri has the highest Ca (7716 mg/kg ww), K (2030.5 mg/kg ww), and P (13,180 mg/kg ww) concentrations. Dactyloptena orientalis exceeds the Cd limit (0.1284 mg/kg ww). Elevated Se levels in fishes were noted, with Dactyloptena orientalis (0.8607 mg/kg ww), Satyrichthys laticeps (0.7303 mg/kg ww), and Snyderina guentheri (0.6193 mg/kg ww). Fish like Pterygotrigla hemisticta contains high Zn (32 mg/kg ww), meeting Recommended Dietary Allowance limits. Deep-sea fish have safe heavy metal levels, but Cd, Se, and Zn exceed acceptable limits. It has been concluded that the consumption of fish species will not pose a potential health risk to humans.

Patterns of the fecal microbiota in the Juan Fernández fur seal (Arctocephalus philippii)

As apex predators, pinnipeds are considered to be useful bioindicators of marine and coastal environments. Endemic to a small archipelago in the South Pacific, the Juan Fernandez fur seal (JFFS) is one of the less-studied members of the pinniped family Otariidae. This study aimed to characterize the fecal microbiome of the JFFS for the first time, to establish a baseline for future studies of host-microbial-environment interactions and monitoring programs. During two consecutive reproductive seasons, 57 fecal samples were collected from seven different JFFS colonies within the Juan Fernandez Archipelago, Chile. Bacterial composition and abundance were characterized by sequencing the V4 region of the 16S rRNA gene. The overall microbiome composition was dominated by five phyla: Firmicutes (40% ±24), Fusobacteria (30% ±17), Bacteroidetes (22% ±10), Proteobacteria (6% ±4), and Actinobacteria (2% ±3). Alpha diversity was higher in Tierras Blancas. However, location was not found to be a dominant driver of microbial composition. Interestingly, the strongest signal in the data was a negative association between the genera Peptoclostridium and Fusobacterium, which explained 29.7% of the total microbial composition variability between samples. The genus Peptoclostridium has not been reported in other pinniped studies, and its role here is unclear, with interpretation challenging due to a lack of information regarding microbiome functionality in marine mammals. As a first insight into the JFFS fecal microbiome, these results contribute towards our understanding of the natural microbial diversity and composition in free-ranging pinnipeds.