Effects of on-demand feeding on sea urchin larvae (Paracentrotus lividus ; Lamarck, 1816), development, survival and microalgae utilization

Abstract

This study compared the growth of sea urchin Paracentrotus lividus larvae cultured using two different rearing methods: a variable method based on a variable amount of feed (microalgae) and seawater exchange (30% or 50%) established according to the phytoplankton concentration in the larval cultures and a fixed method characterized by a fixed amount of feed and seawater exchange. Three microalgae diets, Isochrysis sp. (Tahitian strain, T-Iso), Chaetoceros gracilis and a 50:50 mixed diet, were tested with both rearing methods. Larval development and survival were assessed at the 6-arm pluteus stage (P6), competence (Cp) and metamorphosis (Mt). Data showed that the variable method reduced the requirements for phytoplankton and seawater exchange. Indeed, through the optimization of feed rations, it was possible to reduce the production of debris and settled phytoplankton, minimizing the need for water exchanges. Higher larval survival resulted at Cp and Mt stages for those reared with the variable method as opposed to the fixed one. Survival and development were also influenced by the tested dietary treatments: at Mt stage, the mixed diet resulted in a higher larval survival (63.3 AE 8.9%) than T-Iso (19.7 AE 12.1%) and C. gracilis (23.4 AE 15.1%) (P < 0.05). These results suggest that the use of the variable method improves the larval survival and development and also it reduces resource consumption (phytoplankton, seawater use and work effort), which in turn could potentially improve the hatchery production of P. lividus. Effects of on-demand feeding on sea urchin larvae B Gianni et al.

Optimising microalgae diets in sea urchin Paracentrotus lividus larviculture to promote aquaculture diversification

“…galbana (clone T-ISO) (T) did not provide fast growth. These results agree with previous studies in which this species appeared unsuitable compared to other microalgae for echinoderm larval culture (Brundu et al, 2016b;Fenaux et al, 1988;Pechenik, 1987;Schiopu et al, 2006).…”

“…For all dietary treatments tested, larvae reached the age at competence at 15 DPF, which represents a shorter larval stage duration than in previous studies (Brundu et al, 2016a(Brundu et al, , 2016bCarboni et al, 2012;Gosselin and Jangoux, 1996;Liu et al, 2007). This may be explained by the faster growth of larvae when they are reared at low density (1 larva/ml, present study) as highlighted by Buitrago et al (2005) and Kalam Azad et al (2012).…”

“…A low feeding rate could reduce the amount of non-consumed phytoplankton at the bottom of the tanks and consequently the requirement for water exchange, which is crucial to maintain water quality but can affect survival rate (Cárcamo et al, 2005;Kalam Azad et al, 2010). Likewise, a high manual water exchange rate is time-consuming for producers and stressful for larvae (Brundu et al, 2016b;Carboni et al, 2014).…”

Effects of lipid sources on the growth performance, gonad development, fatty acid profile and transcription of related genes in juvenile sea urchin ( Strongylocentrotus intermedius )

“…The roe (gonads) of sea urchins have been considered as a delicacy in many parts of the world, especially in Asia and Europe (Lawrence, 2007). In the last decades, the rapidly increasing market demand for sea urchin roe has resulted in the over‐fishing of the wild stocks worldwide (Brundu et al., 2017; Nhan et al., 2020; Zhang, Cui, & Li, 2019). As an alternative to wild fisheries, aquaculture of sea urchins has been proven to be practical especially with the fast improvement in the stock enhancement and farming technologies (Gibbs, Watts, Lawrence, & Lawrence, 2009; Hammer et al., 2012; Watts, Lawrence, & Lawrence, 2013).…”

Hard time to be parents? Sea urchin fishery shifts potential reproductive contribution of population onto the shoulders of the youngest

“…The fertility of the US individuals was tested according Brundu et al (2016) during the months of maximum gonadal development (i.e. from December to April).…”