Intensive Coastal Shrimp Aquaculture Reduces Zooplankton Abundance and Diversity in the Aquaculture Ponds

Abstract In shrimp aquaculture systems, zooplankton represent a potential food source for larvae and juveniles due to its high nutritional value and size-suitability. Although many studies investigated zooplankton community in various aquaculture systems, little knowledge exists on how this varies among different culture systems. Here, we investigated how zooplankton abundance, diversity and density differ among three shrimp culture systems, namely extensive, semi-intensive and intensive. In total, 28 zooplankton species of 7 different groups were recorded. Copepods, rotifers and decapods were dominant groups, accounting for more than 80% of total zooplankton density. Brachionus plicatilis was the most abundant species. A key finding was that species richness and diversity were higher in extensive and semi-intensive culture than in intensive culture. Zooplankton density was highest (10 6 ind/m 3 ) in extensive systems which was 3 and 8 times higher than in intensive and semi-intensive systems, respectively. Density of zooplankton was lowest (4886 ind/m 3 in May) in the early stage of culture but notably higher in the later stage (8.9 × 10 5 ind/m 3 in June and 5.9 × 10 5 ind/m 3 in July). This is probably because the zooplankton community in the culture systems experienced a high predation pressure by cultured organisms during the early stage but were gradually less preyed upon over time. The obtained findings suggest that zooplankton assemblages in the ponds appeared to be an important food source for cultured organisms, especially during the early stage. It would be beneficial to establish an abundant assemblage of zooplankton in shrimp culture system prior to stocking.