Latest scientific news about sea cucumbers
Picture: Møreforsking - All rights reserved
By Gyda Christophersen & Jan Sunde / Møreforsking
Towards aquaculture of red sea cucumber – initial studies at Møreforsking
Currently there is a strong demand for sea cucumbers, especially in the Asian market. Because the supply is limited, efforts are made to develop aquaculture of several species worldwide. The red sea cucumber (Parastichopus tremulus) has the potential for being a new species for aquaculture in Norway. For this to happen it is necessary to advance the knowledge about the life history parameters of P. tremulus and the conditions affecting reproduction, growth and survival during different life stages.
At Møreforsking Ålesund AS in Norway, several ongoing projects are focusing on different parts of the value chain. Special attention is given to the reproductive cycle and early life stages in the bilateral project "Emerging species for sea cucumber aquaculture" funded through the bilateral program SANOCEAN 2018-2023 (South Africa-Norway Co-operation on Ocean research, including blue economy, climate change, the environment and sustainable energy). As a first step towards establishing a protocol for hatchery production of P. tremulus in Norway, Møreforsking has described the annual reproductive cycle of the species from the fjords close to Ålesund in Møre & Romsdal, western Norway (62°N) based on monthly sampling. Determining the natural spawning season is essential to control the reproductive biology and spawning in captivity. The work identified the time of mature gonads, and sea cucumbers were successfully induced to spawn in June-July using different induction methods (temperature increase, air exposure and salinity reduction). Thermal shock was found to be the most successful method for spawning induction. Natural spawning has been observed in storage tanks from June, but also as late as September.
The next step towards aquaculture is production of juveniles provided successful fertilization and survival through the larval stages and metamorphosis. Parastichopus spp. develops via a planktonic feeding auricularia larval stage that can last for weeks or months, followed by a short non-feeding doliolaria stage, before metamorphosis and benthic life as pentactula larvae and juveniles. This year Møreforsking obtained sea cucumbers from by-catch of local commercial trawl and pot fisheries and induced them to spawn in the laboratory. Repeated egg batches were successfully fertilized, and the larval development was followed for several groups. The pelagic larval stages until late auricularia were achieved and growth and survival estimated based on size measurements and sample counts. Larvae were kept alive for 50-60 days in 10 L volumes at 14-16 °C and fed a mix of instant algae, although larvae never reached the settling stage. Initial studies on sperm motility showed increased motility and viability from May to July.
Further studies on broodstock performance and gamete quality are suggested in a research proposal “Farming down the food web - towards aquaculture of red sea cucumber focusing on reproduction and early life stages” which is under evaluation at the Research Council of Norway. Møreforsking Ålesund AS and the Mercier lab in Newfoundland from the HOLOSUSTAIN network are involved in collaboration with Swedish colleagues. If funded, substantial understanding about the requirements of the red sea cucumber in aquaculture will be obtained.
Some recent publications of interest
regarding sea cucumber functionality:
A sea cucumber (Holothuria leucospilota) polysaccharide improves the gut microbiome to alleviate the symptoms of type 2 diabetes mellitus in Goto-Kakizaki rats.
Food Chem Toxicol. 2019 Oct 15:110886. doi: 10.1016/j.fct.2019.110886.
Bello SA, Torres-Gutiérrez V, Rodríguez-Flores EJ, Toledo-Román EJ, Rodríguez N, Díaz-Díaz LM, Vázquez-Figueroa LD, Cuesta JM, Grillo-Alvarado V, Amador A, Reyes J, García-Arrarás JE. (2019) Insights into intestinal regeneration signaling mechanisms. Dev Biol. pii: S0012-1606(18)30503-7. doi: 10.1016/j.ydbio.2019.10.005. [Epub ahead of print].
Sea cucumber Holothuria polii (Delle Chiaje, 1823) as new model for embryo bioassays in ecotoxicological studies.
Chemosphere; 2019 Sep 121 240 124819. doi:10.1016/j.chemosphere.2019.124819
The first cloned echinoderm tumor necrosis factor receptor from Holothuria leucospilota: Molecular characterization and functional analysis.
Fish Shellfish Immunol.; 2019 Aug 051 doi:10.1016/j.fsi.2019.08.008