With the extension of the post-catch circulation time, a series of changes had taken place in the soft tissue of the live clams, resulting in the decline of its quality. This study investigated the quality changes of clams (Ruditapes philippinarum) in cold chain and was mainly focused on the rehydration process, which included gradient heating rehydration (GR) and sudden heating rehydration (SR). It was found that the GR had a better effect on the quality of clams than the SR. The GR stage clams showed a higher survival rate, glycogen content and adenylate energy charge (A.E.C) value than the SR stage clams. Conversely, the GR stage clams showed lower lactic acid content and K-value than the SR stage clams. The results indicated that the gradient heating rehydration was beneficial to the quality of clams. The transportation and rehydration strategies benefited both producers and shellfish merchants to save total cost.

This study focused on the optimization of the flexural strength of bio-composite samples of palm kernel, whelks, clams, periwinkles shells and bamboo fiber, reinforced with resin for engineering applications. The aim of the study was to: formulate different samples of bio-composite reinforce with resin for engineering applications and to evaluate the flexural strength, of the fabricated composite. The hand lay-up technique was used for the composites produced by incorporating different percentage compositions of the shells/fiber (10%, 15%, 20%, 25% and 30%) into varied proportions of epoxy resin and catalyst. The cured samples after 24hours were subjected to tensile, impact, flexural and water absorption test. The experiments were conducted using Taguchi optimization method L25 (5x5) with five design parameters and five level combinations in Minitab 18 statistical software. The results showed that the average values of flexural was 114.87MPa when compared to the unreinforced of 72.33MPa bio-composite. The study recommended that agricultural waste like palm kernel shells, whelk shells, clams, periwinkle shells and bamboo fiber, should be converted into important engineering applications.

To investigate the mass mortality of asari clams triggered by upwelling-driven hypoxia, we conducted biological and oceanographic observations of the Rokujo tidal flat in Mikawa Bay, central Japan. In addition, a simple laboratory experiment was conducted using sediments on a tidal flat containing macrobenthos to examine the possibility of hydrogen sulfide formation in tidal flats. The results of field observations showed that the number and biomass of asari clams decreased from September to October in the tidal flat when hypoxia was intermittent. In particular, hypoxia persisted for approximately one week from September 21, which was associated with the calm weather and stagnation of tidal currents owing to the neap tide. The hydrogen sulfide concentration in the water directly above the sediment exceeded 30 mg L-1 after 3 days of incubation. Our results suggest that the mass mortality of asari clams may be caused by the high concentration of hydrogen sulfide produced by sulfate reduction, which is attributed to the chain of biological die-off caused by the upwelling of hypoxic water mass accompanied by meteorological events, and calm conditions such as the neap tide period.