Evaluation of suitable micro‐algal diets for intensive culture of the calanoid copepod Acartia bilobata

Abstract

Copepods are alternative live feed in marine fish hatcheries, and the quality and type of micro-algal diets influence their culture productivity. Three algal species of different groups including prymnesiophyte: Isochrysis galbana (Iso), the diatom: Chaetoceros muelleri (Cht) and eustigmatophyte: Nannochloropsis occulata (Nan) were fed to the calanoid copepod Acartia bilobata. Selected algae were offered as mono-algal diets: T1-Iso, T2-Cht and T3-Nan or as mixed algal diets: T4-Nan + Cht, T5-Nan + Iso, T6-Iso + Cht and T7-Iso + Cht + Nan. Reproductive parameters, egg production, hatching success, nauplii and copepodite survival, development and first maturity, were closely monitored. Results illustrated that I. galbana was the most suitable diet for this copepod species, supporting higher average relative egg production (5631.62 ± 133.49 egg L−1 day−1), hatching success (96.32 ± 1.40%) and superior adult survival (44.44 ± 3.20%). Different algal diets influenced the nauplii and copepodite survival rate. Maximum survival to adults (56.67 ± 3.78%) and shortened development time (5.75 ± 0.12 days) and time to first maturity (4.50 ± 0.12 days) were observed when fed with I. galbana. The groups fed with C. muelleri exhibited lower survival (6.67 ± 0.67%) during development into adults, and the group fed with N. occulata alone or with C. muelleri did not survived till the adults. Amongst seven algal diets tested, I. galbana was found ideal for maximizing culture productivity, and hence recommended for intensive culture of A. bilobata.