Warming of the planet is indisputable and will lead to more frequent extreme events, such as droughts. From June 2003 to March 2008, the effects of variations in river flow, associated with drought conditions, were studied in the fish assemblage of the Mondego estuary, Portugal. Over this time, two distinct hydrological periods were identified: non-drought years and drought years, with consistent changes in the fish assemblages. In the drought years, salinity increased inside the estuary, displacing the estuarine brackish habitats to more upstream areas. During this period, new marine adventitious species were found mainly in the most downstream areas, while the freshwater species disappeared from the Mondego estuary catchment area. For the marine estuarine-dependent species that use estuaries as nursery areas, a decrease in abundance was observed during the drought years, owing to the decrease in freshwater flow and reduced river plume to the coastal area. In non-drought years, there were higher densities of most species and the more important species of the fish community. Our work shows that extreme events such as droughts, related to climatic changes, influenced the structure and composition of the Mondego estuary fish assemblages, and should be further considered when undertaking management plans for transitional waters.

Farmed seabass have higher adiposity than their wild counterparts and this is often attributed to carbohydrate feeding. Whether this reflects a reduction in fat oxidation, increased de novo lipogenesis (DNL), or both, is not known. To study the effects of high carbohydrate diets on hepatic triglyceride biosynthesis, hepatic TG deuterium (²H) enrichment was determined following 6 days in ²H-enriched tank water for fish fed with no-carbohydrate diet (CTRL), and diets with digestible (DS) and raw starch (RS). Hepatic fractional synthetic rates (FSR, %day^-1) were calculated for hepatic TG-glyceryl and FA moieties through ²H NMR analysis. Glyceryl FSR exceeded FA FSR in all cases, indicating active cycling. DS fish did not show increased lipogenic compared to CTRL-fed fish despite a ~3-fold higher hepatic TG level. RS fish had lower glyceryl FSR compared to the other diets and negligible levels of FA FSR despite similar hepatic TG levels to CTRL. DS-fed fish showed higher activity for enzymes that can provide NADPH for lipogenesis, relative to CTRL in the case of G6PDH and relative to RS for both G6PDH and 6PGDH. This approach indicated that elevated hepatic adiposity from digestible starch feeding was not attributable to increased de novo lipogenesis.