Effects of Paphia textzle larvae on ingestion and digestion of different microalgae species

【Objective】To clarify the suitable species of microalgae bait for Paphia textzle larvae at different developmental stages，so as to provide seeding strategy and references for large-scale artificial breeding of seedlings.【Method】 Two-year old P. textzle caught from the natural waters of Tieshangang District，Beihai City，Guangxi Province were cultivated as parents. When cultivating D-shaped larvae were，species of microalgae，Chlorella vulgaris，Nannochloropsis oculata，Dunaliella salina，Platymonas subcordiformis，Pavlova viridis，Dicrateria zhanjianggensis，Isochrysis galbana， Chaetoceros muelleri，and Phaeodactylum tricornutum were fed to P. textzle larvae every 3 days at larval stage. The ingestion and digestion effects of larvae feeding by different species of microalgae were observed at different stages.【Result】 The size of the newly hatched larvae（D-shaped larvae）（shell length×shell height）of the P.textzle was（82.49±3.02）μm×（63.98±2.16）μm. They developed to the early umboveliger at 4 dph（days post hatch）with a size of（115.89±3.86）μ m×（101.62±3.80）μ m. Then they entered metamorphosis stage with a size of（205.61±15.84）μ m×（182.61±13.53）μm at 13 dph. They became byssus at 15 dph with a size of（225.63±8.99）μm×（198.65±8.25）μm. The P. textzle larvae also ingested during the movement process，forming a water flow through the swing of cilia，and the microalgae entered the groove of the larva with the direction of the water flow，and entered the stomach under the swing of the groove cilia，and the microalgae in the stomach quickly spined and digested under microvilli wiggles. Larvae could ingest C. vulgaris，N. oculata，P. viridis，D. zhanjianggensis，and I. galbana at 1 days post hatch（dph）and very few larvae could ingest D. salina small individual at 4 dph. The larvae began to ingest P. subcordiformis and C. muelleri small individual at 10 dph. P. tricornutum could not be ingested by larvae during the planktonic period. It found that C. vulgaris and N. oculata was more difficult to digest than others of nine microalgae.【Conclusion】During the breed of P. textzle larvae，the spherical shape with small particle size of P. viridis，D. zhanjianggensis and I. galbana that is easier to digest would be used as bait at first，and followed by D. salina，P. subcordiformis and C. muelleri.