Salinity Tolerance and the Effect of Salinity and Algal Feed on the Demographics of Cultured Harpacticoid Copepods Tisbe holothuriae and Tigriopus sp. from the Messolonghi Lagoon (W. Greece)

Abstract

The locally isolated harpacticoid copepods Tigriopus sp. and Tisbe holothuriae were subjected to salinity tolerance experimentation at salinities under and above of 40 ppt, and presented high halotolerances in Tigriopus LC50 (24 h) of 1 ± 4.43 ppt and 132 ± 5.35 ppt, respectively, and in Tisbe of 15 ± 2.41 ppt and 93 ± 3.23 ppt, respectively. Tetraselmis suecica, among other microalgal feeds (Asteromonas gracilis, Rhodomonas salina, Dunaliella salina and Isochrysis galbana), resulted in the higher production of nauplii in Tigriopus and R. salina and D. salina in Tisbe (also close to T. suecica in Tigriopus). The demographics (number of nauplii, egg sacs, completion of hatching) of both copepods, using combinations of salinities in the range of 22–60 ppt and D. salina and R. salina as feeds, exhibited almost the same preference for microalgae but were negatively affected by the salinity of 60 ppt. The present experiments showed that these local copepods that have extreme salinity tolerance and a wide preference for easily cultured microalgae can be used in ecological studies and for mass production as live feed in marine fish hatcheries.