Frontiers in cryopreservation techniques for marine invertebrate larvae

Abstract

The present review focuses on the crucial role of marine invertebrate cryopreservation as a promising and imperative technique in preserving genetic material, and for aquaculture, conservation, and the future of cryobanking. A total of 35 species from 16 families, including crustaceans (nauplius and protozoea), echinoderms (prism and pluteus), polychaetes (chaetiger), scleractinian corals (planula), and mollusks (trochophore, veliger, D-larva, and umbo) larvae were cryopreserved successfully. The optimal protocol for each species and larval stage were investigated with respect to (1) suitable cryoprotective agents (CPAs), (2) cooling rates, (3) storage temperatures, (4) holding times, and (5) thawing rates. Most studies on marine invertebrate larvae are only proof-of-concept experiments and have yet to be implemented on a larger scale for mass production. This is due to the challenging task of creating effective protocols for each larval stage of each species. Developing a protocol for cryopreservation requires two critical steps: (1) identifying suitable CPAs (i.e., concentration, type, and exposure time) for the specific species and larval stage and (2) determining the appropriate freezing, and thawing. Implementing such protocols prevents cryoinjuries, such as ice crystal formation, pH fluctuations, osmometric effects, cold shock, or CPA toxicity. Innovative techniques have been developed to advance the process of cryopreservation and cryobanking despite the challenges posed by the current protocols' scalability. Cryobanks are highly sought after, particularly in the medical and agricultural industries. More attention must be given to this issue to ensure the availability of reliable cryobanks for these important marine species.