Microbial and Microparasite Abundance in Cage-Cultured Abalone Haliotis asinina

Abstract

Microorganisms and parasites are some of the major threats to aquaculture, including abalone culture worldwide; however, few reports concerning these microbes and parasites in abalone have been published. Moreover, several studies were conducted to determine the microbial load and degree of parasitism in abalone of other species but not the abalone Haliotis asinina of the Philippines, particularly in Palawan. This study was conducted to assess the abundance of microorganisms and microparasites in the cage-cultured abalone. The microbial abundance was determined by dilution plate count technique. Slide sampling and scoring was performed using methylene blue and acetocarmine stains to determine the abundance of microparasites. Results revealed that fungi have the highest total abundance among the four functional groups of microorganisms present in abalone. The Gram-positive bacteria had the highest abundance in the digestive tract (178 × 103 CFU/g). Actinomycetes had the highest abundance in the gonad (35 × 103 CFU/g). On the other hand, fungi had the highest abundance in the gills (198 × 103 CFU/g) and in the mantle (95 × 103 CFU/g). The highest abundance of microorganisms was found in the digestive tract of abalone. Microparasites such as trematodes, nematodes, copepods, and protozoans were found in cage-cultured abalones. Among these microparasites, trematodes were found abundant in the gills, whereas protozoans were abundant in the stomach of abalones.