Influence of pseudo-green water on growth, colouration, and survival in European lobster (Homarus gammarus) larvae

With the depletion of European lobster (Homarus gammarus) wild stocks from historic overexploitation, the attention has turned towards restocking, stock enhancement programs and farming potential. The early life larval stages of the European lobster present a major barrier to hatchery production efforts due to low survival rates. Green water techniques are rapidly growing due to their ability to improve nutrition quality. This study explores the potential benefits of using pseudo-green water. This is determined by adding microalgae to the rearing environment of larvae by analysing the effects on growth and survival. The commonly used algal species: Tetraselmis suecica (TS), Dunaliella salina (DS), and Nannochloropsis sp. (N) were added as monoculture or mixture treatments to a controlled European lobster larvae-rearing environment over thirteen days. The trial consisted of seven permutations of algal treatments (TS, DS, N, TS+DS, TS+N, DS+N, and TS+DS+N) and one control group, with clear water conditions using length measurements, survival rates and colouration to determine treatment impacts at the end of the trial. Results indicate that mixtures of algal species outperformed monocultures and clear water regarding growth performance. Nannochloropsis sp. is of significant benefit to growth performance. Algal mixes containing Nannochloropsis sp. resulted in significantly better growth than D. salina monoculture treatment. There were no significant differences in survival rates between treatment groups.