Shrimp's Secret: How Algae and Temperature Affect Their Health

Ever thought about how algae can influence shrimp? A fascinating study looked into this by focusing on Litopenaeus vannamei, a common shrimp species. Researchers examined how adding a specific algae, Haematococcus pluvialis, to shrimp food affects their growth, immune system, and gut bacteria at different water temperatures. They compared three diets: a typical 20% fish meal diet (control), a diet with only 10% fish meal (low-fish meal or LFM), and the LFM diet with added algae. Six shrimp groups were tested at normal (30°C) and cool (20°C) temperatures over eight weeks. Results showed that shrimp fed the LFM diet with algae (NT_LFM_HP and LT_LFM_HP) gained more weight than those on the LFM diet alone. These algae-fed shrimp also had higher astaxanthin levels and brighter body colors. Interestingly, the shrimp's antioxidant powers, measured by superoxide dismutase activity and total antioxidant capacity, were better in cooler temperatures. However, shrimp eating algae had higher antioxidant levels regardless of temperature. At lower temperatures, these shrimp showed the highest levels of genes related to immune pathways too. Gut bacteria varied significantly between groups, with temperature and fishmeal content playing roles. Vibrionaceae bacteria were much lower in the cool-water, algae-fed group. Actinomarinales bacteria were more abundant in cooler waters, with the algae group showing the most. These findings hint that reducing fishmeal in shrimp food may make them more vulnerable. But adding H. pluvialis seems to help shrimp adapt to colder water.