Effects of variations of environmental factors and algal bloom on fish larvae in Southern central Vietnam

Abstract

A multivariate analysis was conducted to assess the impact of variations of environmental factors, such as temperature, salinity, dissolved oxygen (DO), total suspended solid (TSS), nitrite (NO 2 -N), nitrate (NO 3 -N), ammonium (NH 3 , 4 -N), phosphate (PO 4 -P), and silicate (SiO 3 -Si) concentrations, chlorophyll (chlor) and algal bloom on natural fish larvae in Binh Thuan waters, Vietnam. Temporal and spatial variations of environmental factors were correlated with the abundance and diversity of fish larvae. The abundance and diversity of fish larvae decreased at the sites of the algal blooms. Five environmental factors: temperature, salinity, nitrite, phosphate and silicates showed a statistically significant impact on the fish larvae, but other factors showed weaker and statistically not significant effects. In the months of algal blooms, phosphate, silicate, nitrite, nitrate, ammonium and salinity influenced blooms substantially, while the effects of temperature were mainly confined to the months without blooms of algae. Algal blooms were lethal to fish larvae and juveniles leading to a decline in their abundance and diversity. This will affect and restrict the process of recruitment of fish stocks in the region.

Combined effects of a simulated marine heatwave and an algal toxin on a tropical marine aquaculture fish cobia ( Rachycentron canadum )

“…Furthermore, the impacts of harmful algal blooms on aquaculture may amount to approximately $8 billion per year, globally (Brown et al, 2020) that may further challenge the aquaculture production and food security (Brown et al, 2020;Quang et al, 2016).…”

“…Secondly, the occurrence of MHW (Doan et al, 2018) and toxic algal blooms (Quang, Hai, & Lam, 2016) often coincides with the period of fish production. Therefore, knowledge of how and to what extent aquaculture species will be affected by MHW and toxic algae is of crucial importance for production.…”