Resumen de Filtration Rate of the Ascidian Ciona savignyi and Its Possible Impact
Satoshi Nakai, Jun Ya Shibata, Akira Umehara, Tetsuji Okuda, Wataru Nishijima
Ciona savignyi is an invertebrate filter feeder with an expanding invasive range in the world and a biofouling organism settling on artificial substrates such as fish net. In this study, we investigated the effect of body length and temperature on its filtration rate. As C. savignyi increased in size, filtration rate also increased. Optimal filtration occurred at a temperature of 24–25 °C. The effect of body length on filtration rate was expressed using an exponential function and the effect of temperature (15–27 °C) was calculated using a polynomial function. An equation to predict the filtration rate of C. savignyi was developed, by combining the terms for body length and temperature. The predicted filtration rates calculated using this power function showed good agreement with observed values. The filter-feeding ascidian, C. savignyi, is a biofouling organism that frequently grows on aquaculture structures. Using published data describing the numbers and weights of the cultured Japanese scallop (Mizuhopecten yessoensis) and of biofouling C. savignyi attached to pearl fishing nets in the Kugurizaka experimental fishing grounds, the filtration potential of both species was estimated as a case study. The results suggest that C. savignyi attached to the nets has the potential to negatively impact the growth of the Japanese scallop through competition for food.
