Impact of nine macroalgal diets on growth and initial reproductive investment in juvenile abalone Haliotis tuberculata

Abstract

The commercial culture of Haliotis tuberculata has recently started in Europe. As abalone is herbivorous, the use of local collected algae as feed may appear advantageous. The nutritional value of eight monospecific seaweed diets was studied using Palmaria palmata (Rhodophyta), filamentous algae, mainly Gracilaria sp. (Rhodophyta), Enteromorpha sp. and Ulva lactuca (Chlorophyta), together with Saccharina latissima, Saccorhiza polyschides, Laminaria digitata and Laminaria hyperborea (Ochrophyta, Phaeophyceae) and a mixed macroalgal diet. An integrative approach consisted in monitoring the seasonal composition changes of these algae in terms of protein, lipid, soluble carbohydrate, fatty acid and amino-acid contents, and to relate it to seasonal growth and reproduction investment during a largescale experiment. Abalone and algae were studied for one year in commercial sea-cage structures. Abalone fed with monospecific diet using either P. palmata or S. latissima, and with mixed diet presented the best growth rate, muscle ratio and gonad development. Seasonal daily weight gain was mainly associated with n-3/n-6 ratio, soluble carbohydrate content and total protein content. In term of aminoacid contents, the daily weight gain was associated with free phenylalanine as well as isoleucine levels. Moreover, 90% of 2-years old abalone started gonad development but less than a quarter featured a fully matured gonad. The gonad development of H. tuberculata was mostly associated to total valine, methionine, leucine, arginine and isoleucine levels. The age of initial sexual maturity in H. tuberculata turned to be a highly plastic trait in response to different growth rates and algal diets. Even if P. palmata is the best option for growth performance, mixed diets should probably be preferred to a monospecific diet in order to avoid too high pressure on a single algal resource. Highlights ► Mixed diets conferred higher fitness than the average of single-species diets, but not for the best single species ► Abalone are likely to invest more energy in muscle and gonad developments when fed on Palmaria palmata. ► At 2-year-old, an average of 90% of H. tuberculata started gonad development but <23% of the cohort had a full development ► Soluble carbohydrate, n-3/n-6 and total protein are the major algal components for reproduction and growth performance

Haliotis tuberculata, a generalist marine herbivore that prefers a mixed diet, but with consistent individual foraging activity

“…Choosing a mixed diet is probably the best compromise for large marine herbivores, consistent with nutritional advantages and conferring significantly higher fitness than the average of single‐species diets, but not for the best single prey species (review by Lefcheck, Whalen, Davenport, Stone, & Duffy, 2013). In a one‐year experiment, we have confirmed the advantage of a mixed diet foraging strategy on Haliotis tuberculata , showing that the mixed diet was the second best strategy in terms of growth and reproductive development after a monospecific diet of the best single alga, P. palmata (Roussel et al, 2019). In the wild, P. palmata is often likely to be unavailable.…”

“…Aliquots were transferred in glass test tubes previously heated for 6 hr at 450°C and containing 6 ml of a chloroform/methanol mixture (2/1, v/v), in accordance with the Folch, Lees, and Stanley (1957) method. The method is described in detail in Roussel et al (2019). Quantitative fatty acid spectra obtained by gas chromatography were used to calculate the molar content of each fatty acid in the samples.…”

“…Aliquots were transferred in glass test tubes previously heated for 6 hr at 450°C and containing 6 ml of a chloroform/methanol mixture (2/1, v/v), in accordance with the Folch, Lees, and Stanley (1957) method. The method is described in detail in Roussel et al (2019).…”

Effects of sampling and storage procedures on 16S rDNA amplicon sequencing results of kelp microbiomes

“…They contribute to primary productivity and are habitat engineers providing food and shelter to the local biodiversity (Schiel and Lilley, 2007;Schiel and Foster, 2006). In addition, kelp species are important in many industries to produce alginates (Peteiro, 2018), human food, medicine (Smit, 2004), or food for abalone aquaculture (Roussel et al, 2019).…”

Effect of dietary protein, vitamin E, and vitamin C levels on the growth and gonad development of hybrid male abalone (Haliotis fulgens ♂×H. discus hannai ♀) by the orthogonal array design

“…For example, protein is one of the most important nutrients related to the growth and gonad development of most aquatic animals (Cottier- Cook and Kelly, 2007;Xu et al, 2016). It was well demonstrated that high protein diets could improve the gonadal development and reproduction of juvenile abalone (H. midae), adult sea urchin (Psammechinus miliaris), brood shes (Channa marulius) and sea urchin (Lytechinus variegatus) (Hafeez-ur-Rehman et al, 2017; He in et al, 2012; Pantazis et al, 2000;Roussel et al, 2019). However, protein de ciency could lead to a small size of the egg and its cytoplasm bulk (Bilbao et al, 2012).…”