Two Tropical Marine Copepods Demonstrate Physiological Properties Needed for Mass Production

Abstract

Two live feed relevant copepods for larval fish and shrimps, Pseudodiaptomus annandalei and Apocyclops royi, were predominant year-round in a tropical brackish fishpond system. The ponds environment is harsh concerning physicochemical properties; temperature 20–32 °C, salinity 15–23 besides abrupt salinity drops 15–9, frequent severe hypoxia, and poor nutritional seston quality. In 50 studies investigating several physiological endpoints, P. annandalei performs optimally within 18–32 °C and salinity 10–30 and A. royi within 24–32 °C and salinity 10–32. Most extreme, A. royi is reported in situ at salinity 50 and in the laboratory; it can adjust from salinity 20 to freshwater within just two generations when fed on Baker’s yeast. Both species and in particular A. royi have developed an outstanding capability to convert ingested seston with poor fatty acid composition into the necessary long-chained polyunsaturated fatty acids (PUFAs) characterizing their tissues. Hence, they self-enrich their bodies’ fatty acid profiles. Their physiological plasticity is likely a prerequisite for existing extensive mass production in the harsh pond environment. Moreover, A. royi exhibit additional traits, that is, high density tolerance qualifying also for intensive mass production suggesting it as the most promising live feed of the two species for fish and shrimp hatcheries.

Keywords:

• Physico-chemical challenges
• physiological tolerance
• PUFA-poor seston
• biosynthesis of LC-PUFAs
• fishponds
• live feed

Acknowledgements

I am indebted to my dear colleague Prof. Jiang Shiou-Hwang, National Taiwan Ocean University for fruitful collaboration and co-supervision of several PhD students studying the target copepod species over the years, and to the fishponds manager allowing the Roskilde University field team access to sampling in the Taiwanese pond facilities. Moreover, a deep gratitude to the many national- and international students and collaborators that have contributed to the international literature on investigations of the two target copepods and to whom it is with a substantial proud they are called collaborators by working together in the field and laboratory, and by supervising their theses, co-authored journal articles and not least by countless fruitful discussions. Also, a thank goes to Laboratory technician Rikke Guttesen for extensive culture work, Dr. Per Meyer Jepsen and Dr. Haidi Cecilie Petersen for graphics assistance, and laboratory technician Mette Flodgaard and Dr. Hans van Someren Gréve for offering the privilege to use their photographs of the copepods in the present contribution.

Funding

This work was supported by the Environmental dynamics research group Roskilde University, Department of Science and Environment, Dk-4000 Roskilde.

Disclosure statement

The author declare having no known competing financial interests or personal relationships that could have influenced the work reported in this paper.