Larval settlement, early growth and survival of haliotis tuberculata coccinea using several algal cues

Abstract

Settlement of Haliotis tuberculata coccinea larvae was examined in the presence of crustose coralline algae (CCA), Ulvella lens, and Ulva rigida. Germlings of the 2 green macroalgae of different age, enrichment level, and in combination were tested as settlement cues, and CCA was tested as a positive control. Larval settlement was the highest on CCA (61 %) tailed by a 45-day-old mix of U. lens and U. rigida (52%) and 45-day-old U. rigida (46%). Settlement was the lowest (about 3%) on a mix of 4-day-old U. lens and U. rigida and 45-day-old enriched or unenriched U. lens. In all treatments, postlarvae were fed for 4 wk with a mix of diatoms (Amphora sp., Proschkinia sp., Nitzschia sp., and Navicula incerta); postlarval growth was the best on the 45-day-old mix of U. lens and U. rigida. This substrate was also the best of the green macroalgae germlings substrates tested for settlement induction and provided good survival rates. The substrate protein content correlated negatively with larval settlement and survival. The algal cues were differentiated by their fatty acid composition. Fatty acids such as 18:ln-7, 18:2n-6, 16:4n-3, arachidonic acid, and eicosapentaenoic acid were suggested to affect settlement and survival. The fatty acids correlated with settlement were different from the ones associated with survival rates, except eicosapentaenoic acid, which correlated with both. The results of this study show the high value of U. rigida for H. tuberculata postlarvae, and the influence of substrate age on the settlement success.