Effect of temperature and salinity on in-vitro population growth of copepode Oithona (Copepoda: Cyclopoidae). Temperature-salinity Oithona culture

Abstract

The marine copepods culture has been considered a great resource for feeding in marine aquaculture. Oithona is the most abundant genus in the oceans and that is why they are the largest contributors of live prey in fish larvae. The present study aimed to identify the influence of temperature and salinity on the population growth of Oithona sp. under laboratory conditions. Copepods were cultivated (n: 15 ind/200 ml in three experimental temperatures: 21, 26, 31°C and in three salinities: 20, 30, and 40‰), which were monitored and adjusted daily. Copepods were fed based on a microalgae culture Isochrysis sp. at a continuous density of 600.000 cel/ml. for 15 days. At the end of the experiment, Oithona sp presented significant statistical differences (p < 0.05), in population growth, with a higher population density at 40‰ (8.040 ± 6.265.2 ind/ 200ml), at a temperature of 31°C. Also, it was shown that the variable salinity alone did not influence the population growth of the copepod, while, if it was related to the water temperature, it presents statistically significant differences (p < 0.05), in all possible combinations. We concluded that Oithona sp. can be well adapted to higher temperature and salinity conditions in which the optimal salinity and temperature variables rate is 31°C and 40‰ to reach a higher development. These conditions improve the rate of reproduction, population growth, and its development in culture.