Comparative effects of microalgal species and food concentration on suspension feeding and energy budgets of the pearl oysters Pinctada margaritifera and P. maxima (Bivalvia:Pteriidae)

Abstract

ABSTRACT-This study aimed to determine the influence of microalgal species and food concentration on various physiological parameters and Scope for Growth (SFG) in adults of 2 pearl oysters, Pinctada margantifera and P maxima. Clearance rate, pseudofaecal production rate, absorption efficiency, respiration rate and excretion rate were determined over a range of food concentrations using 2 microalgal diets, Tah~tian Isochrysis sp. (T-Iso) and Dunaliella primolecta at 28'C. Clearance, pseudofaecal production and respiration rates were significantly affected by microalgal diet. From these results, and because of the higher energy content of T-Iso, pearl oysters feeding on T-lso had maximum values of SFG that were 1.5 to 2 1 times higher than when feeding on D. pnmolecta. Clearance rate and absorption efficiency were significantly related to food concentration as negative exponential relationships (p c 0 001). Generally, pseudofaecal production, respiration and excretion rates were significantly related to food concentration as positive linear relationships (p < 0.005) Optimal food concentrations for max~mum SFG for P margarjtifera and P maxima were 1 to 2 mg I-' and 2 to 3 mg I-', respectively. P. maxima was better adapted to a wider range of food concentrations. P. maxima maintained positive SFG up to 9 mg I-' food concentration when feeding on T-lso and up to 7 mg I-' when feeding on D. primolecta, while equivalent values for P. margaritifera were 7 mg 1-' and 5 mg I-', respectively. Thesc results are in accordance with P. maxin~a occurring in a wider range of habitats than P margaritiferd, and experiencing greater concentration ranges of suspended particulate matter

Influence of farmed pearl oysters and associated biofouling communities on nutrient regeneration in lagoons of French Polynesia

“…At 18, 23 and 28°C, Saucedo et al (2004) also reported no variations of NH 4 excretion efficiency for Pinctada mazatlanica. Over a similar range of temperatures (23 to 28°C), clearance rate and respiration have also been reported to be relatively independent of temperature for P. margaritifera and P. maxima, highlighting a probable acclimatization capacity of pearl oysters to moderate seasonal variations (Yukihira et al 1998).…”

“…Factors which may influence nitrogen excretion by pearl oysters include individual size, temperature and trophic level (Yukihira et al 1998, Saucedo et al 2004, Mondal 2006. During this study, nutrient fluxes of clean pearl oysters (PO units) were constant over the year and were not correlated with the biomass of pearl oysters or with the environmental parameters recorded.…”

Feeding adaptations of the pearl oysters Pinctada margaritifera and P. maxima to variations in natural particulates

“…Similarly, when feeding on pure algal diets, Pinctada maxima was more efficient than P. margaritifera at gaining energy at high cell concentrations (Yukihira et al 1998b). However, there were several differences between the feeding and energy budgets of pearl oysters supplied with mono-specific algal diets (Yukihira et al 1998a,b) and those fed natural SPM.…”

“…In laboratory studies, Yukihira et al (1998b) revealed that Pinctada maxima had higher cleara.nce rates (CR) than P margantifera at relatively high concentrations of pure microalgae, Dunaliella primolecta and Isochrys~s aff, galbana (T-Iso). P. maxima also had higher absorption efficiencies throughout most of the range of food concentrations (range: 0.1 to 3.1 mg I-').…”

Scope for growth of juvenile Cortez oyster, Crassostrea corteziensis fed isocaloric diets prepared with microalgae and cereal flours

“…The physiological index Scope for Growth (SFG) determines the energy potentially available for growth and reproduction (Winberg, 1960) and is calculated as the difference between absorbed energy and respired and excreted energy. SFG has been used in marine bivalves to determine, for example, physiological plasticity of native and invasive species (Sará et al, 2008;NievesSoto et al, 2011), feeding range for aquaculture purposes (Ibarrola et al, 1998;Yukihira et al, 1998;Kesarcodi-Watson et al, 2001a, 2001bVelasco, 2007), identifying physical and chemical parameters for optimum growth (Yukihira et al, 2000;Soria et al, 2007), and population health (Din & Ahamad, 1995).…”