To investigate the effects of temperature and salinity on filtration and oxygen consumption rate of Scapharca broughtonii spat with different growth stages. This study was conducted under six different water temperatures and five different salinity conditions. The spat were divided into three groups of different shell sizes and filtration rates were estimated by Neutral red. The results showed that in all of the three groups, the highest filtration rates appeared at 20 °C, and the highest one was 1.89±0.12 L g h−1 in the group with the lowest shell length (11.8±2.1 mm). The filtration rates in every group increased with the rise of salinity in the range from 10 to 40 g L−1, and the highest one is 2.62±0.21 L g h−1 in the lowest shell length group. The trends of oxygen consumption rates were similar to filtration rates. The highest rates were 0.189±0.003 mg g h−1 at 20 °C and 0.308±0.018 mg g h−1 at a salinity of 40 g L−1 in the group with the lowest shell length. And the results showed that the smaller the shell size, the higher the filtration and oxygen consumption rate.

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To evaluate the potential to control red tides using the mass-cultured heterotrophic grazer, rotifer Brachionus plicatilis, the effects of environmental factors (water temperature and salinity) on physical activities (filtration and oxygen consumption rate) of B. plicatilis were estimated. Experiments were conducted at different water temperatures (15, 20, 25, 30 and 35°C) and salinities (20, 25, 30, 35 and 40 PSU) ) was observed at 35°C and salinity 40 PSU, and the lowest one (1.01 ±0.15 ng rot -1 h -1 ) was observed at 15°C and salinity 20 PSU. Results from this present study indicated that the filtration and oxygen consumption rate of the rotifer were significantly influenced by the water temperature and salinity. The utilization of rotifer for red tide control has to consider the influence of environmental factors.