This study investigated the growth, survival and fatty acid composition of sea urchin Paracentrotus lividus larvae fed four microalgal diets: Cricosphaera elongata, Pleurochrysis carterae, Tetraselmis suecica and Dunaliella tertiolecta (control). Larvae were successfully raised to competence for metamorphosis when fed C. elongata, P. carterae and D. tertiolecta diets but significant differences were found in survival rate and development. Larvae fed C. elongata showed 3 times higher survival and 20 % faster development than larvae fed the other two microalgae diets that supported development. In contrast, T. suecica failed to fully support development and larvae stalled at the four arms stage for more than 30 days. The urchin larvae could accumulate long-chain polyunsaturated fatty acids (LC-PUFA) such as docosahexaenoate (DHA; 22:6n-3), eicosapentaenoate (EPA; 20:5n-3) and arachidonate (ARA; 20:4n-6), either by assimilation and retention of dietary fatty acids, and/or synthesis from α-linolenic acid 18:3n-3 and linoleic acid 18:2n-6. Moreover, an accumulation of n-3 LC-PUFA and higher EPA/DHA and EPA/ARA ratios appeared to be associated with improved larval performance. The results indicate that live microalgae species, with appropriate fatty acid profiles are able to improve P. lividus larval performance, ultimately increasing hatchery profitability.

First paragraph: Sea urchin gonad is a valuable food product. The world urchin harvest increased from 48 000 tonnes in 1982 to a peak of 120 000 tonnes in 1995 mainly due to the expansion of the Chilean, Canadian and US (Californian and Maine) fisheries (Andrew, Agatsuma, Ballesteros, Bazhin, Creaser, Barnes, Botsford, Bradbury, Campbell, Dixon, Einarsson, Gerring, Hebert, Hunter, Hur, Johnson, Juinio-Menez, Kalvass, Miller, Moreno, Palleiro, Rivas, Robinson, Schroetr, Steneck, Vadas, Woodby & Xiaoqi 2002). However, this was followed by a sharp decline during the late 90′s and first decade of the new millennium (Pearce 2010) mainly due to overfishing. Japan is considered as the main sea urchin consumer in 1995 importing over 6000 metric tonnes of sea urchin gonads with a value of 251 million dollars. By 2007, Japanese imports had increased by 300% (Pearce 2010). The retail price of unprocessed fresh sea urchin in Europe varies greatly depending on the season, country, species and retailer type and can vary between 0.30 and 3 € per individual, whereas the price of processed gonads can reach 150 € kg-1

The explosion of the Deepwater Horizon (DWH) oil platform resulted in large amounts of crude oil and dispersant Corexit 9500A® released into the Gulf of Mexico and coincided with the spawning season of the oyster, Crassostrea virginica. The effects of exposing gametes and embryos of C. virginica to dispersant alone (Corexit), mechanically (HEWAF) and chemically dispersed (CEWAF) DWH oil were evaluated. Fertilization success and the morphological development, growth, and survival of larvae were assessed. Gamete exposure reduced fertilization (HEWAF: EC201h=1650μg tPAH50L(-1); CEWAF: EC201h=19.4μg tPAH50L(-1); Corexit: EC201h=6.9mgL(-1)). CEWAF and Corexit showed a similar toxicity on early life stages at equivalent nominal concentrations. Oysters exposed from gametes to CEWAF and Corexit experienced more deleterious effects than oysters exposed from embryos. Results suggest the presence of oil and dispersant during oyster spawning season may interfere with larval development and subsequent recruitment.