Growth and photosynthetic rates of Chlamydomonas plethora and Nitzschia frustula cultures isolated from Kuwait Bay, Arabian Gulf, and their potential as live algal food for tropical mariculture

With a view to utilize local algae as food organisms in mariculture, the green alga Chlamydomonas plethora and the diatom Nitzschia frustula were isolated and studied from the unique coastal waters arid zone off Kuwait. Batch cultures of C. plethora and N. frustula had maximum division rates (lmax) of 2.5 and 3.4 day)1, respectively. Cultures grown for 36 h yielded comparable growth rates. Photosynthesis-irradiance relationships in cultures harvested at various phases of growth showed that cultures attained log phase after 1-day growth and yielded the highest assimilation numbers (PB m: lg C [lg Chl a])1 h)1): 22.8 for C. plethora and 18.1 for N. frustula. Their initial slopes (aB: ng C [lg Chl a])1 h)1 [lmol m)2 s)1])1 were also the highest observed so far: 79.5 for C. plethora and 39.6 for N. frustula. Photoinhibition was low. Compared with these, assimilation numbers in senescent cultures of 20-day growth were